selective rearrangement of terminal epoxides into ... · s5 figure 1. complete conversion of 1a and...

Supporting Information

Selective rearrangement of terminal epoxides into methylketones catalysed by a nucleophilic rhodium-NHC-pincer complex

Eva Jürgens,a Barbara Wucher,a Frank Rominger,b Karl W. Törnroos,c Doris Kunza*

a Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen,

Auf der Morgenstelle 18, D-72076 Tübingen (Germany)

b Institut für Organische Chemie, Heidelberg University

Im Neuenheimer Feld 250, D-69120 Heidelberg (Germany)

c Department of Chemistry, University of Bergen,

Allegaten 41, 5007 Bergen (Norway)

Contents

1. Experimental procedures and analytical data S2

2. Crystallographic details for compounds 4a and 4b S17

3. 1H and 13C NMR spectra of the new compounds S19

4. IR spectra of 1 and 2a S31

5. Catalytic epoxide rearrangement: optimisation of the reaction conditions regarding additive and solvent S33

6. References S33

Electronic Supplementary Material (ESI) for Chemical Communications.This journal is © The Royal Society of Chemistry 2014

S2

1. Experimental procedures and analytical data

General Procedures. Unless otherwise noted, all reactions were carried out under an argon

atmosphere in dried and degassed solvents using Schlenk techniques. Acetonitrile and thf

were purchased from Sigma Aldrich, dried, and degassed using an MBraun SPS-800 solvent

purification system. All lithium and sodium salts used were obtained from commercial

suppliers, dried in vacuum and used without further purification. Epoxides were obtained

from commercial suppliers and degassed under vacuum prior to use. The rhodium complex 1

was synthesised according to the literature procedure.[1] 1H and 13C NMR spectra were

recorded using a Bruker ARX 250 and AVANCE II +400 spectrometer. 1H and 13C chemical

shifts are reported in ppm and calibrated to TMS on the basis of the residual solvent proton

signal as an internal standard (1.73 ppm, thf-d8; 1.94 ppm, CD3CN; 5.32 ppm,

dichloromethane-d2). Assignment of peaks was made using 2D NMR correlation spectra. IR

spectra were recorded on a Bruker Vertex70 instrument. The mass spectrum was recorded

on a Thermo Finnigan TSQ 70.

Synthesis of rhodium complex 1:

We already reported the synthesis of this compound.[1] Additional 1H NMR data of compound

1 in thf-d8 and C6D6:

1H NMR (thf-d8, 400.11 MHz): δ = 1.55 (s, 18H, t-Bu), 4.20 (s, 6H, NCH3), 7.45 (d, 3J = 2.0

Hz, 2H, H-4´), 7.82 (d, 4J = 1.8 Hz, 2H, H-2/7), 8.16 (d, 4J = 1.8 Hz, 2H, H-4/5), 8.23 (d, 3J =

2.0 Hz, 2H, H-5´).

1H NMR (benzene-d6, 400.14 MHz): δ = 1.56 (s, 18H, t-Bu), 3.74 (s, 6H, NCH3), 6.14 (d, 3J =

1.6 Hz, 2H, H-4´), 7.31 (d, 3J = 1.6 Hz, 2H, H-5´), 7.63 (d, 4J = 2.0 Hz, 2H, H-2/7), 8.49 (d, 4J

= 2.0 Hz, 2H, H-4/5).

13C{1H}NMR (benzene-d6, 100.61 MHz): δ = 32.5 (C(CH3)3), 35.0 (C(CH3)3), 40.3 (N-CH3),

110.9 (C2/7), 114.7 (C4/5), 115.7 (C5´), 122.7 (C4´), 125.4 (C1/8), 129.3 (C4a/5a), 37.3

(C1a/8a), 139.2 (C3/6), 182.5 (d, 1JRhC = 45.9 Hz, C2´), 199.8 (d, 1JRhC = 71.4 Hz, CO).

S3

General Procedure for the Meinwald rearrangement with rhodium complex 1:

O

1

2

3

4

5

6

Rh(bimca)CO[1] 1 (2 mg, 4 mol, 10 mol%) and lithium bis(trifluoromethanesulfonimide) (1

mg, 10 mol%) were placed into a J. Young NMR tube and 1,3,5-trimethoxybenzene as

internal standard and benzene (0.5 mL) were added. At last dried 1,2-epoxyhexane (4.2 μL,

35 mol) was added and the reaction mixture was heated to 60 °C and monitored via 1H

NMR spectroscopy during the time given.

1H NMR (benzene-d6, 400.11 MHz): δ = 0.77 (t, 3J = 7.4 Hz, 3H, H-6), 1.08 (ps sext, 3J = 7.5

Hz, 2H, H-5), 1.34 (ps quint, 3J = 7.7 Hz, 2H, H-4), 1.64 (s, 3H, H-1), 1.87 (t, 3J = 7.3 Hz, 2H,

H-3).


In the glove box, 10 mg 1 (18.5 µmol) and lithium bis(trifluoromethanesulfonimide) (5 mg, 1

eq) were dissolved in 0.5 mL benzene-d6 in a J. Young NMR tube. Propylene oxide (1.5 µL,

1.2 eq) was added to the reaction mixture, which was allowed to react at room temperature

for 10 minutes. The resulting species 2 (R1, R2 = CH3) was characterised by NMR and IR

spectroscopy in solution.

1H NMR (benzene-d6, 400.14 MHz): δ = 1.04 (d,3J = 5.8 Hz, 3H, CH3), 1.35 and 1.52 (each s

br, each 9H, t-Bu), 3.56–3.63 (m, 1H, CH), 3.69 and 3.85 (each s br, each 3H, NCH3), 6.32

and 6.49 (each s br, each 1H, H-4’, H-9’), 7.11 and 7.45 (each s br, each 1H, H-Carb), 7.16

(from 2D) and 7.49 (each s br, each 1H, H-5’, H-10’), 7.86 and 8.07 (each s br, each 1H, H-

Carb). The signal at 7.16 ppm is covered by the solvent signal and was assigned via 2D

spectra (1H1H-COSY, 1H13C-HMBC, 1H13C-HSQC) as well as the signal for the CH2-group

that is covered by the t-Bu-group (1.52 ppm) signals.

1H NMR (toluene-d8, 400.14 MHz): δ = 1.04 (d,3J = 5.8 Hz, 3H, CH3), 1.31 and 1.51 (each s

br, each 9H, t-Bu), 1.37–1.44 (s br, 2H, CH2) 3.56–3.63 (m, 1H, CH), 3.65 and 3.82 (each s

br, each 3H, NCH3), 6.26 and 6.49 (each s br, each 1H, H-4’, H-9’), 7.09 and 7.40 (each s br,

S4

each 1H, H-Carb), 7.15 and 7.52 (each s br, each 1H, H-5’, H-10’), 7.74 and 7.95 (each s br,

each 1H, H-Carb).

13C{1H} NMR (benzene-d6, 400.14 MHz): δ = 19.1 (CH3), 23.2 (d br, 1JRhC = 23.0 Hz, CH2),

32.0 and 32.2 (C(CH3)3), 34.4 and 34.6 (C(CH3)3), 38.7 and 39.0 (NCH3), 80.5 (s br, CH),

109.6 and 109.9 (CCarb), 114.2 and 114.5 (CCarb), 115.2 and 116.6 (C5´, C10´), 118.5 and

121.7 (C1, C8), 123.4 and 123.7 (C4a, C5a), 124.5 and 124.7 (C4´, C9´), 135.5 (C1a, C8a),

138.2 (C3, C6), 174.1 and 174.5, (each d, each 1JRhC = 56.0 Hz, C2´, C7´), 207.1 (d, 1JRhC =

46.2 Hz, CO).

𝜈(benzene-d6, cm-1) = 2046 (vw br, Rh-CO), 1716 (w, acetone), 1645 (w), 1588 (w).

(Formation of complex 2 was confirmed by NMR spectroscopy prior to the IR-measurement.

Therefore benzene-d6 was used as a solvent.)

In situ generation of type 2 complexes by reaction of 1a/b and epoxides in benzene-d6:

Other unsymmetrical complexes of type 2 can be generated at room temperature by reacting

Rh(I) complexes 1a and 1b with 2 eq of epoxide and 2 eq of LiNTf2 in benzene-d6. Reaction

of complexes [Rh(bimca)(CO)] (1a) or [Rh(bimcaEt)(CO)] (1b) with propylene oxide and 1,2-

epoxyhexane lead clearly to the respective complexes of type 2, but the amount depends on

the steric demand of both reaction partners. Complex 1a (R1 = CH3) reacts with both

epoxides at room temperature completely to 2a/b, while 1b (R2 = C2H5) leads to a mixture of

1b and 2c/d.

2a/b (R1 = CH3, R

2 = CH3 (a), C4H9 (b))

2c/d (R1 = C2H5, R

2 = CH3 (c), C4H9 (d))

R2 = CH3, C4H9

1

R1 = CH3 (a), C2H5 (b)

S5

Figure 1. Complete conversion of 1a and propylene oxide (1, blue) or 1,2-epoxyhexane (2, green) at room temperature to

complexes 2a and 2b.

Figure 2. Reaction of 1b with propylene oxide (1, blue) and 1,2-epoxyhexane (2, green) at room temperature led to the

analogue complexes 2c and 2d. In this case the conversion of 1b is incomplete and led to a ratio of 1b:2c = 4:3 or 2d (1b:2d

= 8:1).

Eva344_Zugabe_Propoxid_30min.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 Chemical Shift (ppm)

-0.035 -0.030 -0.025 -0.020 -0.015 -0.010 -0.005

0 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050 0.055 0.060 0.065 0.070 0.075

1

2

1b 1b

1b 1b

1b (N-CH 2 -)

1b (-C(CH 3 ) 3 )

and 4d 1b ( -CH

3 ) and 4d

2d 2d 2d 2d 2d 2d 2d

2c 2c 2c 2c 2c 2c 2c 2c 2c 2c

1,2-epoxyhexane

propylene oxide

1,2-epoxyhexane

1b 1b 1b 1b

1b (N-CH 2 -)

epoxyhexane and 2d

1b ( -C2H5 ) and 2c

2c

Eva340.010.001.1r.esp

9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.5 Chemical Shift (ppm)

-0.10

-0.05

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

1

2

2b 2b 2b

2b 2b 2b

2b 2b

2b

2a 2a 2a 2a 2a 2a 2a

2a

2a

2a

2a

1,2-epoxyhexane

propylene oxide propylene oxide Standard (TMB) Standard (TMB)

benzene 2b

2b

1,2-epoxyhexane

2b

S6

After full conversion of the epoxide the starting complexes 1a/b are recovered (by NMR

spectroscopy).

Figure 3. Monitoring the reaction of 1b with propylene oxide in benzene-d6; spectrum 1 (blue): before addition of

propylene oxide, spectrum 2 (green): after addition of 2 eq propylene oxide, and spectrum 3 (grey): after 16 h at room

temperature (full conversion of the epoxide to acetone and recovery of complex 1b).


Route 1:

In the glove box, 15 mg of 1 (26 µmol) were dissolved in 0.5 mL tetrahydrofurane-d8 with

propylene oxide (2 µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The

reaction mixture was allowed to react at room temperature for 4 days, after which the

complete formation of 3 was observed. Slow decomposition during workup prevents further

analysis.

Eva344_Startspektrum.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.5 Chemical Shift (ppm)

-0.15

-0.10

-0.05

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

1

2

3

1b 1b 1b 1b 1b N-CH2-

1b -CH2CH3

1b (-C(CH3)3)

standard (TMB)

Standard (TMB)

2c 2c 2c 2c 2c 2c 2c 2c 2c 2c propylene oxide

propylene oxide

+ acetone

C6D5H

C6D5H

3

S7

1H NMR (thf-d8, 400.14 MHz): δ = 1.16 (d,3J = 6.2 Hz, 3H, CH3), 1.50 and 1.51 (each s, each

9H, t-Bu), 1.65–1.75 (m, 2H, CH2), 3.55–3.66 (m, 1H, CH), 3.98 and 3.99 (each s, each 3H,

NCH3), 7.21 and 7.22 (each d, each 3J = 2.1 Hz, each 1H, H-4´, H-9´), 7.61 and 7.64 (each d,

each 4J = 1.5 Hz, each 1H, H-4, H-5), 7.99 and 8.00 (each d, each 4J = 1.5 Hz, each 1H, H-2,

H-7), 8.18 and 8.19 (each d, each 3J = 2.1 Hz, each 1H, H-5´, H-10´).

13C{1H} NMR (thf-d8,100.61 MHz): δ = 22.3 (CH3), 26.1 (d, 2JRhC = 30.0 Hz, CH2), 32.9 and

32.9 (C(CH3)3), 35.5 (2x C(CH3)3), 39.5 and 39.8 (NCH3), 79.4 (CH), 109.5 and 109.7 (C4,

C5), 114.3 and 114.5 (C2, C7), 117.6 and 117.8 (C5´, C10´), 124.6 and 124.8 (C4´, C9´),

125.7 and 126.3 (C4a, C5a), 127.6 and 127.5 (C1, C8), 136.9 and 137.0 (C1a, C8a), 136.9

and 137.0 (C3, C6) 180.5 and 181.0 (each d, each 1JRhC = 41.0 Hz, C2´, C7´), 229.4 (d, 1JRhC

= 43.3 Hz, CAcyl).

MS (FAB+): m/z = 628.3 (1 %) [M+H]+, 642.3 (100 %) [M-C3H6O2]+

.

Route 2:

In the glove box, 15 mg of 1 (26 µmol) were dissolved in 0.5 mL acetontirile-d3 with propylene

oxide (2 µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The reaction

mixture was allowed to react at room temperature for 24 h at 60 °C, after which the complete

formation of the new species 3 was observed. Slow decomposition during workup prevents

further analysis.

1H NMR (CD3CN, 400.14 MHz): δ = 1.14 (d, 3J = 6.1 Hz, 3H, H-15), 1.51 (s, 18H, t-Bu),

1.56–1.63, 1.64–1.73 (each m, each 1H, CH2), 3.55–3.66 (m, 1H, CH), 3.95 and 3.95 (each

s, each 3H, NCH3), 7.23 and 7.24 (each d, each 3J = 2.2 Hz, each 1H, H-4´), 7.68 and 7.70

(each d, each 4J = 1.5 Hz, each 1H, H-4, H-5), 8.07 and 8.08 (each d, each 4J = 1.5 Hz, each

1H, H-2, H-7), 8.18 and 8.20 (each d, each 3J = 2.1 Hz, each 1H, H-5´).

13C{1H} NMR (CD3CN, 100.61 MHz): δ = 22.4 (CH3), 26.6 (d, 2JRhC = 36.7 Hz, CH2), 30.0 and

32.9 (C(CH3)3), 36.0 (2x C(CH3)3), 40.0 and 40.3 (NCH3), 80.0 (CH), 110.8 (C4, C5), 115.0

and 115.3 (C2, C7), 125.7 and 126.0 (C4´, C9´), 126.2 and 126.7 (C4a, C5a), 127.2 and

127.4 (C1, C8), 136.0 and 136.6 (C1a, C8a), 139.0 (C3, C6) 179.6 and 179.8 (each d, each 3JRhC = 40.7 Hz, C2´, C7´), 228.8 (CAcyl, no coupling detected due to low intensity). Signals for

C5´ and C10´ could not be detected due to overlap with the signal for CD3CN.

MS (FAB+): m/z = 628.3 (1 %) [M+H]+, 642.3 (100 %) [M-C3H6O2]+

.

S8

Synthesis of rhodium complex 4a:

In the glove box, 15 mg 1 (26 µmol) were dissolved in 0.5 mL thf-d8 with propylene oxide (2

µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The reaction mixture was

allowed to react at 80 °C for 4 days, after which the formation of yellow precipitate was

observed. The solvent was removed and the yellow residue dissolved in CD2Cl2 and

characterised NMR spectroscopically.

1H NMR (CD2Cl2, 400.14 MHz): δ = 1.55 (s, 18H, t-Bu), 2.01 (br s, 3H, CH3), 3.96 (s br, 1H,

CH), 4.18 (s, 6H, NCH3), 7.17 (d, 3J = 1.7 Hz, 2H, H-4´), 7.65 (d, 4J = 1.3 Hz, 2H, H-2/7), 8.03

(d, 3J = 1.7 Hz, 2H, H-5´), 8.14 (d, 4J = 1.3 Hz, 2H, H-4/5).

13C{1H} NMR (thf-d8, 100.61 MHz): δ = 21.0 (CH3), 31.9 (C(CH3)3), 34.7 (C(CH3)3), 38.7

(NCH3), 93.6 (CH), 110.8 (C4´), 114.7 (C2/7), 116.3 (C5´), 125.3 (C4/5), 127.6 (C4a/5a),

135.0 (C1a/8a), 137.2 (C1/8), 139.3 (C3/6), 174.6 (d, 1JRhC = 112.6 Hz, C2´), 189.8 (d, 2JRhC =

89.0 Hz, CORh), the CAcyl signal could not be detected.

The equilibrium between Rh-catalyst 1 and complex 3a in thf-d8:

Experiment whether species 3a is able to release acetone and such reacts back to catalyst 1

or complex 3a gets only deactivated by dehydrogenation to 4a (Figures 4-7).

Complex 1 was dissolved with a catalytic amount of LiCl and propylene oxide in thf-d8 (Figure

4). After 20 h at room temperature a mixture of 1 and 3a (2:1) and a small amount of Rh

complex 4a was obtained. Upon evaporation of the solvent and redissolving the residue in

thf-d8, the ratio of complexes 1 to 3a remained unchanged, but all organic components were

removed (Figure 5). After 1 day at room temperature acetone was generated and the 1H

NMR spectrum shows complex 1 as the only organometallic species (Figure 6). The thf-d8

and all volatiles were evaporated again and the residue dissolved in dichloromethane-d2 (as

4a

4a 3a 1

S9

the solubility of 4a is much better in CD2Cl2). The 1H NMR spectrum gives evidence for the

formation of 4a (Figure 7).

Thus we could demonstrate that some amount of complex 3a releases acetone under

regeneration of 1 as well as it can be dehydrogenated to complex 4a.

Eva357_1H_Startspektrum.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0

Chemical Shift (ppm)

0

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0.055

0.060

0.065

0.070

0.075

0.080

0.085

0.090

0.095

Norm

alized Inte

nsity

0.670.4513.063.962.3617.124.043.943.561.085.850.330.210.190.131.920.190.220.152.010.440.141.940.220.231.980.15

0.1

489

1.2

461

1.2

588

1.5

369

1.5

486

1.5

761

1.7

659

2.3

062

2.6

205

2.8

824

3.6

246

3.7

408

4.0

427

4.0

487

4.2

435

4.3

227

6.0

841

7.2

751

7.2

808

7.2

976

7.3

026

7.5

019

7.5

069

7.5

275

7.5

323

7.6

897

7.7

733

7.8

550

7.8

592

8.0

299

8.0

746

8.1

810

8.2

747

8.2

798

8.3

549

std

thf

thf

grease1

3

4

t-Bu's

std

3

Eva357_1H_Startspektrum.esp

8.25 8.00 7.75 7.50 7.25


0

0.005

0.010

0.015

0.020

0.025

0.030

Norm

alized Inte

nsity

0.210.190.131.920.190.220.152.010.440.141.940.220.231.980.15

7.2

751

7.2

808

7.2

976

7.3

026

7.5

019

7.5

069

7.5

275

7.5

323

7.6

501

7.6

897

7.7

733

7.8

550

7.8

592

8.0

299

8.0

746

8.1

810

8.1

848

8.2

329

8.2

573

8.2

747

8.2

798

8.3

492

8.3

549

1 1 1 1

333334 4 4 4

propyleneoxide

propyleneoxide

Figure 4.

1H NMR spectrum recorded directly after the addition of propylene oxide (std = 1,3,5-trimethoxybenzene).

Eva357_thf_aufgenommen.esp

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0


0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

Norm

alized Inte

nsity

2.430.962.0517.146.0827.360.66111.440.675.368.941.4030.041.640.442.640.900.990.512.941.730.622.750.940.932.930.49

0.1

126

1.1

409

1.1

564

1.1

727

1.1

883

1.2

924

1.4

999

1.5

124

1.5

396

1.7

3003.5

892

3.7

042

3.8

8064

.0050

4.2

039

4.2

825

6.0

476

7.2

437

7.2

492

7.2

639

7.2

686

7.4

7077

.4932

7.4

987

7.6

129

7.6

5417.8

181

7.8

220

8.0

0008

.1438

8.1

477

8.2

363

8.2

417

std std

thf

thf

grease

1

1

3

4

Eva357_thf_aufgenommen.esp

8.0 7.5


0

0.005

0.010

0.015

Norm

alized Inte

nsity

1.640.442.640.890.980.512.931.730.612.750.940.932.930.49

7.2

798

7.2

852

7.3

000

7.3

046

7.5

013

7.5

067

7.5

293

7.5

347

7.6

489

7.6

528

7.6

863

7.6

901

7.7

741

7.7

780

7.8

541

7.8

580

8.0

251

8.0

360

8.0

702

8.0

741

8.1

798

8.1

837

8.2

490

8.2

544

8.2

723

8.2

777

8.3

516

8.3

570

1 1 1 1

33333

4 4 4 4

t-Bu's

3

std

3

Figure 5.

1H NMR spectrum after removing all volatiles in vacuo and redissolving the residue in thf-d8 (std = 1,3,5-

trimethoxybenzene).

S10

Figure 6. After 1 day at room temperature only species 1 can be detected and some acetone is produced (std = 1,3,5-

trimethoxybenzene).

Figure 7.

1H NMR spectrum after removing all volatiles and redissolving the residue in CD2Cl2 (std = 1,3,5-

trimethoxybenzene).

Eva357_thf_aufgenommen_1d_rt.esp

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5


0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Norm

alized Inte

nsity

1.781.5145.341.051.0114.13115.941.0910.5830.003.633.413.453.47

0.1

117

1.1

744

1.1

896

1.2

919

1.5

390

1.7

300

2.0

474

3.5

595

3.5

890

3.7

046

4.0

464

4.2

082

6.0

476

7.5

034

7.8

230

8.1

473

8.2

458

std

std

thf thf

grease

111

1

1

3

1 acetone

Eva357_2.040.001.1r.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.5


0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

Norm

alized Inte

nsity

1.3625.201.100.530.230.241.435.270.651.920.220.492.002.440.572.01

0.1

181

1.2

995

1.5

745

1.8

022

2.0

458

2.3

701

3.5

963

3.6

723

3.9

567

3.9

852

4.2

313

4.2

561

5.3

504

6.0

998

7.2

031

7.3

079

7.5

499

7.6

817

7.7

789

8.0

551

8.1

828

8.2

173

std

std

thf thf

grease

11 + 31

1

1

1

33

3

3

3

3

1

3

3

dcm

4

4

4 4 4 4

4

S11

Dehydrogenation of complex 3 to the deactivation product 4:

Dehydrogenation of complex 3 to complex 4 is accompanied by hydrogenation of the

acetone (which is formed during the catalysis) to isopropanol (Figure 8).

Figure 8. After evaporation of all volatile compounds the signal at 1.08 ppm (isopropanol) is missing (std = 1,3,5-

trimethoxybenzene).

Eva355_WEand_1Tag_rt.esp

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 Chemical Shift (ppm)

-0.10

-0.05

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

Normalised Intensity

1

2

epoxide epoxide

isopropanol

mixture of 1 and 4

THF THF

All volatile compunds (epoxide + isopropanol) are removed.

std

std

acetone

S12

The equilibrium between 1 and 3 in benzene:

Experiment, if complex 3 (generated in thf-d8) also released acetone upon dissolving in

benzene-d6. Two independent experiments were carried out.

Experiment 1: Complex 1 was dissolved with a catalytic amount of LiCl and propylene oxide

in thf-d8. After 16 h at 60 °C a mixture of complexes 1:3 (1:1) and Rh complex 4 was

obtained. Upon evaporation of the solvent and redissolving the residue in thf-d8 the ratio of 1

to 3 remained constant, but all volatile components were removed. The thf-d8 is again

removed and the residue dissolved in benzene-d6. The 1H NMR spectrum shows 1 as the

major organometallic species. As the acetone signal is covered by the t-Bu signal in

benzene-d6, a few drops of dmso-d6 were added to shift the acetone peak (Figure 11). The

outcome of this experiment gives evidence for the backward reaction of 3 into the catalytic

cycle also in benzene.

Figure 9. Reaction of catalyst 1 with propylene oxide at 60 °C; after 16 h at room temperature a 1:1 mixture of complexes

1:3 was obtained (Standard = 1,3,5-trimethoxybenzene).

Eva353.020.001.1r.esp

8.0 7.5 7.0 6.5 6.0


0

0.005

0.010

0.015

Norm

aliz

ed Inte

nsity

30.001.710.411.390.190.690.290.960.101.581.720.480.211.871.74

8.2

420

8.2

170

8.1

435

8.0

418

7.9

927

7.8

204

7.6

538

7.6

158 7.5

059

7.3

374

7.2

794

7.2

579

6.0

485

Eva353.020.001.1r.esp

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0


0

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0.055

0.060

0.065

0.070

0.075

Norm

aliz

ed Inte

nsity

2.781.8011.1519.5313.441.673.783.583.051.530.776.115.880.841.970.472.551.831.990.560.242.162.01

8.2

420

8.1

435

7.9

927

7.8

204

7.6

538

7.6

158

7.5

059

7.3

374

7.2

794

7.2

579

6.0

485

4.8

927

4.8

443

4.2

089

4.0

191

4.0

103

3.7

056

3.5

909

2.8

361 2.5

871

2.2

729

2.0

490

1.7

300

1.5

400

1.5

130

1.5

007

1.2

232

1.2

105

1.1

915

1.1

760

1.1

573

1.1

421

1a1a1a1a

22

22

x

x

x

2

2

2

1a

Propyleneoxide

Propyleneoxide

Aceton

Standard Standard

Reaction of 1a and LiCl with Propylenoxide

leads to a 1:1 mixture of 1a:2 (60 °C, 16 h)

x

x

x

1 11 1

1

thfthf

2

S13

Figure 10. Reaction mixture after removing all volatiles and dissolving the residue in thf-d8 (Standard = 1,3,5-

trimethoxybenzene).

Figure 11. The reaction mixture after removing all volatiles and dissolving of the residue in benzene-d6 (Standard = 1,3,5-

trimethoxybenzene).

Eva353.030.001.1r.esp

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0


0

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0.055

Norm

alized Inte

nsity

3.070.852.7319.412.7719.310.500.452.646.125.780.372.060.160.101.971.010.982.002.120.351.982.222.08

8.2

471

8.2

420

8.2

008

8.1

445

8.1

404

8.0

384

7.9

921 7.8

220

7.8

179

7.6

703 7.6

538

7.6

117

7.5

113

7.5

059

7.3

368

7.3

320 7.2

785

7.2

737

7.2

604

7.2

557

4.8

934

4.8

443

4.2

095

4.0

172

4.0

096

3.6

330

3.4

785

3.4

015

1.5

377

1.5

108

1.4

988

1.2

907

1.1

893 1

.1545

1.1

389

Eva353.030.001.1r.esp

8.0 7.5 7.0 6.5 6.0


0

0.005

0.010

0.015

0.020

0.025N

orm

alized Inte

nsity

30.002.080.160.102.001.020.992.032.150.352.000.162.252.11

8.2

471

8.2

420

8.2

157

8.1

445

8.1

404

8.0

384 7

.9921

7.8

220

7.8

179

7.6

703

7.6

538

7.6

152

7.6

117 7.5

113

7.5

059

7.3

510

7.3

368

7.3

320

7.2

785

7.2

737

7.2

604

7.2

557

Standard

Standard

thf

thf

11

1 1

22

2 2

1

2

1a +2

2

Eva353.040.001.1r.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5


0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

Norm

alized Inte

nsity

2.949.5311.5021.434.2498.641.236.500.260.252.5530.002.720.602.650.562.39

0.9

245

1.3

543

1.5

365

1.5

580

1.6

920

1.7

110

3.3

153

3.7

531

6.0

495

6.1

597

6.2

541

7.1

600

7.3

200

7.5

144

7.6

339

8.4

393

8.4

903

Standard

1 (C(CH3)3 +

Aceton

Benzol

1 1 1 1

1

1 1 11

Benzol Standard

Eva353.040.001.1r.esp

1.5 1.0


0

0.05

0.10

Norm

alized Inte

nsity

2.949.5311.5021.434.24

0.9

245

1.3

543

1.5

365

1.5

580

1.6

920

1.7

110

Standard

H greaseH grease

Eva353.040.001.1r.esp

8.5 8.0 7.5 7.0 6.5 6.0


0

0.025

0.050

0.075

Norm

alized Inte

nsity

0.252.5530.002.720.602.650.562.39

6.0

495

6.1

597

7.3

200

7.5

144

7.6

339

8.4

393

8.4

903

3 3 3 3

+ 3

3

benzene

benzene

S14

Figure 12. Addition of dmso-d6 to the solution shifts the acetone signal so that it is not covered by the t-Bu signal.

Experiment 2: Complex 1 is dissolved with a catalytic amount of LiCl and propylene oxide in

thf-d8. After 16 h at r.t. a mixture of complexes 1:3a = 1.3:1 was obtained. Upon evaporation

of all volatile compounds and dissolving the residue in thf-d8 the ratio of 1:3a remained con-

stant. All volatiles were removed again in vacuo and the residue was dissolved in benzene-

d6. The 1H NMR spectrum of the suspension clearly shows complex 1 as the only organo-

metallic species. Heating the sample for 1 h at 60 °C led to formation of a new Rh complex.

Upon removal of benzene-d6 in vacuo and dissolving the residue in CD2Cl2 this species was

identified as complex 4a which could have formed from precipitated 3a by dehydrogenation.

Figure 13.

1H NMR spectrum after 16 h at room temperature in thf-d8 (std = 1,3,5-trimethoxybenzene).

Eva353.050.001.1r.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0


0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Norm

alized Inte

nsity

6.381.504.2927.312.186.901.461.990.352.402.270.400.582.39

8.7

016

8.6

183

8.5

480 8.4

441

8.2

502

8.1

413

7.5

623

7.5

277

6.5

465

4.4

540

4.3

628

4.2

298

2.5

000

2.3

134 2

.0996

1.8

766

1.5

507

1.5

399

1.1

602 0.5

447

0.5

130

acetone

Eva356_16h_rt.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0


0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

Norm

alized Inte

nsity

5.5788.7334.5642.135.4126.7926.1423.04109.319.6113.6830.003.344.433.464.663.494.543.454.47

8.2

943

8.2

854

8.2

014

8.0

461

7.8

680

7.7

063

7.6

640

7.5

377

7.3

161

7.2

876

6.0

998

4.2

589

4.0

644

3.7

569

3.6

401

2.0

986 1

.7822

1.5

915

1.5

643

1.5

529 1

.2789

1.2

580

1.2

125

1.1

879

Eva356_16h_rt.esp

8.5 8.0 7.5 7.0


0

0.025

0.050

0.075

Norm

alized Inte

nsity

3.344.433.464.663.494.543.454.47

8.2

943

8.2

854

8.2

545 8.2

014

8.0

461

7.8

680

7.7

063

7.6

640

7.5

377

7.3

161

7.2

876

1 1 1 1

1

1 + 3

33

3 3

3

3

propylene oxid

propylene oxid

acetone

thf

thf

Std

Std

S15

Figure 14.

1H NMR spectrum after removing all volatiles in vacuo and dissolving the residue in benzene-d6 (std = 1,3,5-

trimethoxybenzene).

Figure 15. After heating the suspension for 1 h at 60 °C, the dehydrogenated rhodium species 4 can be detected in the

1H

NMR spectrum (std = 1,3,5-trimethoxybenzene).

Eva356_benzol.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5


0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Norm

alized Inte

nsity

13.2473.247.712.5297.4917.510.825.5929.945.437.391.891.527.74

8.4

707

8.3

145

7.7

455

7.6

150

7.3

002

7.1

416

6.2

354

6.1

382

3.8

772

3.7

327

3.2

966

1.8

999

1.6

932

1.6

085

1.5

393

1.3

566

0.2

778

1 1 1 1

1

thf

Std

Std

1

benzene

Eva356_benzo_60l.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5


0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Norm

alized Inte

nsity

10.66131.641.37115.472.9633.100.440.409.8629.9310.850.6710.990.7210.89

8.4

899

8.4

432

7.6

333

7.5

144

7.3

186

7.1

600

6.2

537

6.1

550

6.1

076

4.3

169

3.7

495

3.6

982

3.3

158

1.8

608

1.5

592

0.2

970

1 1 1 1

1

Std

Std

1 + 4

benzene

4 4 4 4 4 4

S16

Figure 16.

1H NMR spectrum after removing all volatiles in vacuo and dissolving the residue again in benzene-d6 (std = 1,3,5-

trimethoxybenzene).

Figure 17.

1H NMR spectrum after removing benzene-d6 and dissolving the residue in dichloromethane-d2 to verify complex

4 by its chemical shift (std = 1,3,5-trimethoxybenzene).

Eva356_benzol_benzol.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5


0

0.05

0.10

0.15

0.20

0.25

0.30

Norm

alized Inte

nsity

13.55182.931.401.79118.875.2049.930.511.7214.9330.020.0917.111.2715.411.0415.45

8.4

788

8.4

262

7.6

195

7.5

034

7.4

616

7.3

098

7.1

488

6.8

314

6.2

415

6.1

409

4.3

030

3.7

379

3.6

868

3.3

044

1.8

490

1.7

932

1.5

470

1.2

962

0.2

852

1 1 1

1

1

Std

Std

1 + 4

benzene

4

4 4 4

4

4

Eva356.080.001.1r.esp

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0


0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Norm

alized Inte

nsity

161.172.100.843.5535.522.2330.021.2512.841.8113.2715.792.2714.40

1.2

945

1.5

710

1.7

959

2.0

433

3.6

726

3.7

771

3.9

517

4.2

326

4.2

554

4.3

856

5.3

482

6.0

967

7.2

015

7.3

086

7.6

801

7.7

739

8.0

526

8.1

802

8.2

132

1 1 1 1

1

Std

Std

1 + 4

dcm

44 4

4

4

4

thf thf

S17

2. Crystallographic details for compounds 4a and 4b

Crystallographic Data. Data collection was carried out on a Bruker APEX Duo CCD (4b)

with an Incoatec IµS Microsource with a Quazar MX mirror, or a Bruker APEX CCD (4a)

diffractometer, using Mo Kα radiation (λ = 0.71073 Å) and a graphite monochromator in both

cases. Corrections for absorption effects were applied using SADABS.[2] All structures were

solved by direct methods using SHELXS and refined using SHELXL.[3] Further details of the

refinement and crystallographic data are given in the respective CIF-files. CCDC 1018408

(compound 4a) and 1018409 (compound 4b) contain the supplementary crystallographic

data for this paper. These data can be obtained free of charge from The Cambridge

Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

Crystal structure of complex 4a:

In the glove box, 15 mg 1 (26 µmol) were dissolved in 0.5 mL thf-d8 with propylene oxide (2

µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The reaction mixture was

allowed to react at 80 °C for 4 days. Single crystals suitable for X-ray diffraction were

obtained from a saturated solution of the reaction mixture at room temperature. The structure

contains three thf solvent molecules, two of which are disordered.

S18

Crystal structure of complex 4b:

Rh(bimca)CO[1] 1 (2 mg, 4 mol, 10 mol%) and lithium bis(trifluoromethanesulfonimide) (1

mg, 10 mol%) were placed into a J. Young NMR tube and 1,3,5-trimethoxybenzene as

internal standard and benzene (0.5 mL) were added. At last dried 1,2-epoxyhexane (4.2 μL,

35 mol) was added and the reaction mixture was heated to 60 °C. Single crystals from

pentane/thf, suitable for X-ray diffraction were obtained from a saturated solution of the

reaction mixture upon cooling to room temperature. The structure contains a region with

heavily disordered solvent molecules. These could be identified from the shape to be a

pentane and a thf molecule. The two add up to 144 electrons. The Squeeze procedure[4] in

programme package PLATON[5] reports the equivalent of 167 electrons per asymmetric unit,

in total 344 electrons. One ordered thf solvent molecule is included in the reported structure.

The alkyl product suffers from disorder in all three unique molecules. The current model still

suffers from large displacement parameters, in particular at the terminal end of the alkyl

product; also the C-C-distances in those regions suffer from large variations.

S19

3. 1H and 13C NMR spectra of the new compounds

Exemplary 1H NMR spectrum for a Meinwald rearrangement (100 min, 60 °C, 30 mol% LiNTf2, 10

mol% 1, benzene)

1H NMR spectrum of 2 in benzene-d6:

Eva340_Nachtmessung.010.001.1r.esp

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5


0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

0.14

0.15

0.16

0.17

0.18

0.19

Norm

alized Inte

nsity

16.506.4418.0017.6613.435.575.545.022.936.426.391.922.001.754.651.852.26

8.0

469

7.8

492

7.4

695

7.4

337

7.1

416

7.0

900

6.4

755

6.2

946

6.2

284

3.8

373

3.6

808

3.5

864

3.3

023

2.5

443 2.2

909

1.9

707

1.5

773

1.5

060

1.3

379

1.0

160

0.9

118

0.8

988

0.2

761

benzene

std

std

pro

pyle

neoxid

e

propyleneoxide

aceto

ne

S20

13C{1H} NMR spectrum of 2 in benzene-d6:

1H NMR spectrum of 3a in thf-d8:

Eva340_13C.esp

208 200 192 184 176 168 160 152 144 136 128 120 112 104 96 88 80 72 64 56 48 40 32 24 16 8 0


0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

0.14

0.15

0.16

Norm

alized Inte

nsity

208.0

288

207.5

700

207.5

373

175.5

282

175.0

929

174.9

712

174.5

592

162.6

834

138.9

458

136.2

308

125.4

456

125.2

209

124.3

971

124.1

536

122.3

889

119.2

338

117.3

053

115.9

431

115.2

362

114.8

992

110.6

301

110.3

399

93.8

766

81.2

424

55.1

877

48.4

891

48.0

303

39.7

542

39.4

500 35.2

932

32.9

433

32.7

139

30.5

513

24.0

165

23.7

591

20.6

368

18.2

027

1.7

441aceto

ne

benzene

std

std

std

pro

pyle

neoxid

e

pro

pyle

neoxid

e

S21

13C{

1H} NMR spectrum of 3a in thf-d8:

13

C-DEPT-135 NMR spectrum of 3a in thf-d8:

S22

1H

13C-HSQC NMR spectrum of 3a in thf-d8:

S23

1H

13C-HMBC NMR spectrum of 3a in thf-d8:

S24

1H NMR spectrum of 3a in CD3CN:

13C{

1H} NMR spectrum of 3a in CD3CN:

S25

13C-DEPT-135 NMR spectrum of 3a in CD3CN:

1H1H-COSY NMR spectrum of 3a in CD3CN:

S26

1H

13C-HSQC NMR spectrum of 3a in CD3CN:

S27

1H

13C-HMBC NMR spectrum of 3a in CD3CN:

S28

1H NMR spectrum of 4a in CD2Cl2:

13

C{1H} NMR spectrum of 4a in CD2Cl2:

S29

1H

13C-HSQC NMR spectrum of 4a in CD2Cl2

S30

1H

13C-HMBC NMR spectrum of 4a in CD2Cl2

S31

4. IR spectra of 1 and 2a

IR spectrum (benzene-d6) of complex 1.

S32

IR (benzen-d6) of complex 2a.

S33

5. Catalytic epoxide rearrangement: optimisation of the reaction conditions

regarding additive and solvent

Table 1 Optimisation of the reaction conditions: additive and solvent.a

Entry Additive Solvent T [°C] Time [h]

Yieldb,c [%]

1 LiCl thf-d8 60 24 4

2 NaCl thf-d8 60 24 2

3 LiCl CD2Cl2 60 24 0[d]

4 LiCl CD3CN 60 24 0[d]

5 NaBF4 thf-d8 60 24 13

6 NaBPh4 thf-d8 60 24 45

7 NaBPh4 C6D6 60 24 61

8 LiB(C6F5)3 C6D6 60 24 90

9 LiNTf2 C6D6 60 24 >99

a Reaction conditions: 1 (10 mol%), additive (10 mol%), all reactions were carried out in a J. Young NMR tube with 1,2-epoxyhexane (35 μmol) as substrate and 0.5 mL solvent. b The ketone was observed as the sole reaction product. c The yield was determined by 1H NMR using 1,3,5-trimethoxybenzene as internal standard. d Catalyst deactivation due to organometallic side products.[6]

6. References

[1] M. Moser, B. Wucher, F. Rominger, D. Kunz, Organometallics 2007, 26, 1024–1030.

[2] G. M. Sheldrick, SADABS 2012/1; University of Göttingen, Göttingen, Germany, 2012.

[3] a) G. M. Sheldrick, Acta Cryst. 2008, A64, 112-122; b) C. B. Hübschle, G. M. Sheldrick, B. Dittrich,

J. Appl. Cryst. 2011, 44, 1281−1284.

[4] SQUEEZE routine: van der Sluis, P.; Spek, A. L. Acta Cryst. 1990, A46, 194-201.

[5] PLATON: Spek, A. L. J. Appl. Cryst., 2003, 36, 7-13.

[6] In dichloromethane oxidative addition (trans) of the solvent to complex 1 is observed which leads to

[Rh(bimca)Cl(CH2Cl)(CO)]. M. Moser, PhD thesis, Heidelberg University, 2007.

selective rearrangement of terminal epoxides into ... · s5 figure 1. complete conversion of 1a and...

Documents