1

Supporting Information

For

A Hydroquinone Based Palladium Catalyst for Room

Temperature Nitro reduction in water

Alok Kumar,‡ Kallol Purkait,‡ Suman Kr. Dey, Amrita Sarkar and Arindam

Mukherjee*a

Department of Chemical Sciences, Indian Institute of Science Education and Research

Kolkata, Mohanpur-741252, India,

Email: a.mukherjee@iiserkol.ac.in

‡ Both the authors contributed equally to this work

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

2

Contents Experimental Section .............................................................................................................................. 4

Materials and instrumentation ........................................................................................................... 4

Synthesis of 3,5-dimethylpyrazole ...................................................................................................... 4

Synthesis of ligand H2L ........................................................................................................................ 4

Synthesis of complex 1........................................................................................................................ 5

X-ray crystallography .......................................................................................................................... 5

Table S1. Selected crystallographic parameters of 1.2H2O ............................................................ 6

Table S2. Selected bond lengths (Å) and angles (°) for 1.2H2O ....................................................... 6

General catalytic nitro reduction for aryl nitro substrates used for optimization reactions ............. 7

Optimization of complex 1 catalysed reduction of nitro arene reaction. .......................................... 7

Table S3. Screening of solvent for aryl nitro reduction catalyzed by 1.a ........................................ 7

Table S4. Screening of temperature for aryl nitro reduction of Nitrobenzene catalyzed by 1.a .... 7

Table S5. Screening of catalyst loading for aryl nitro reduction of Nitrobenzene catalyzed by 1.a 8

Table S6. Catalytic ability of complex 1 over few other common Pd-compounds.a ....................... 8

Representative procedure of catalytic reduction of nitroarenes substrates ..................................... 8

General catalytic Suzuki-Miyaura cross coupling reaction for aryl halide substrates with phenyl

boronic acid used for optimization reactions ..................................................................................... 8

Optimization of complex 1 catalysed Suzuki-Miyaura cross coupling reaction.................................. 9

Table S7. Optimization of solvent for Suzuki-Miyaura cross coupling reaction of 4-bromo anisole

with phenylboronic acid catalyzed by 1.a ....................................................................................... 9

Table S8. Optimization of base for Suzuki-Miyaura cross coupling reaction of 4-bromo anisole

with phenylboronic acid catalyzed by 1.a ....................................................................................... 9

Table S9. Screening of catalyst loading for Suzuki-Miyaura cross coupling reaction of 4-

bromoanisole with phenylboronic acid catalyzed by 1.a .............................................................. 10

Table S10. Screening of temperature for Suzuki-Miyaura cross coupling reaction of 4-

bromoanisole with phenylboronic acid catalyzed by 1.a .............................................................. 10

Scheme S1. Proposed catalytic cycle for Suzuki-Miyaura cross coupling reaction by complex 1 in

presence of base. The mechanistic pathway is similar to that known in literature.4 ................... 11

Table S11. Suzuki-Miyaura cross coupling reaction of aryl halides with Phenylboronic acid.a .... 11

General procedure for Syntheses of biaryl amines from nitro substituted aryl halides and

phenylboronic acid in one pot using catalyst 1 ................................................................................ 12

Scheme S2. Proposed dehalogenation and nitroarene reduction mechanism by catalyst 1 using

1-bromo-4-nitrobenzene as a model substrate. The complex is dipositively charged when the

palladium is +2 oxidation state. .................................................................................................... 13

Figure S1. 1H NMR spectrum of the reaction between iodobenzene (0.018mmol) and NaBH4 (0.018

mmol) in presence of catalyst 1 (0.003 mmol) in methanol-D4 at 25 °C. More than 90% conversion

3

has occurred within 4-5 min since the spectra shows presence of only ca. 6% substrate

(iodobenzene). .................................................................................................................................. 14

Figure S2. 1H NMR spectrum of reaction mixture of iodobenzene (0.018mmol) and NaBH4 (0.018

mmol) in presence of 1 (0.003 mmol, to have sufficient concentration in 1H NMR). Solvent is

methanol-D4, spectrum recorded at 25 °C and only the relevant region was scanned for better

signal to noise ratio. .......................................................................................................................... 14

Figure S3. 1H NMR of 0.03 mmol of 4-nitrobenzonitrile, 0.24 mmol NaBH4, 0.25 mol% catalyst 1

in D2O. 1,4-dioxane was used for reference. ............................................................................... 15

1H and 13C NMR data of Suzuki-Miyaura product ............................................................................. 15

4-methoxybiphenyl. ...................................................................................................................... 15

4-methylbiphenyl .......................................................................................................................... 15

4-acetylbiphenyl. ........................................................................................................................... 15

4-nitrobiphenyl. ............................................................................................................................ 15

4-cyanobiphenyl. ........................................................................................................................... 16

2-phenylpyridine. .......................................................................................................................... 16

3-nitrobiphenyl. ............................................................................................................................ 16

1H and 13C NMR data of nitro reduction product .............................................................................. 16

Aniline. .......................................................................................................................................... 16

4-aminophenol. ............................................................................................................................. 16

4-cyanoaniline. .............................................................................................................................. 16

4-(pyridin-4-ylmethyl)aniline. ....................................................................................................... 16

4-chloro-1,2-diaminobenzene. ..................................................................................................... 16

1H and 13C NMR data of tandem type reaction product ................................................................... 16

4-aminobiphenyl. .......................................................................................................................... 16

3-aminobiphenyl. .......................................................................................................................... 16

References. ........................................................................................................................................... 32

4

Experimental Section

Materials and instrumentation Palladium chloride was purchased from Precious metal online, Australia. All the other chemicals for

catalysis were purchased from sigma-aldrich, Spectrochem and SRL (India) and used without any

further purification. The solvents were dried or distilled prior to use.1 HPLC grade water and ethanol

from spectrochem, India were used for catalysis. For the characterization of the ligand, metal

complexes and all products of the catalytic reaction we used 400 MHz JEOL NMR spectrophotometer

or 500 MHz BRUKER spectrophotometer. The chemical shifts are reported in parts per million

(ppm). All NMR data were collected at room temperature (25 °C). Melting points and decomposition

temperatures of the compounds were measured in triplicate with one end sealed capillaries using

SECOR India melting point apparatus and the uncorrected values are reported. UV-Visible

measurements were done using Perkin Elmer lambda 35 spectrophotometer. FT-IR spectra were

recorded using Perkin-Elmer SPECTRUM RX I spectrometer in KBr pellets. Perkin -Elmer 2400

series II CHNS/O analyzer was used for elemental analysis. Electro-spray ionization mass spectra

were recorded by +ve mode electrospray ionization, using a Q-Tof micro™ (Waters) mass

spectrometer. Single crystal X-ray data was collected on an Agilent Technologies Supernova (Oxford

Diffraction) diffractometer. The recrystallization yields of isolated ligand and metal complexes,

isolated products of catalysis reaction after column chromatography are reported. All the compounds,

ligand and metal complex were dried in vacuum and stored in desiccators under dark.

Synthesis of 3,5-dimethylpyrazole

The compound was synthesized by dropwise addition of hydrazine hydrate on acetylacetone at 0 °C

and continues the stirring for half an hour. A white coloured product is immediately separated out

from the solution. After 0.5 h white solid was collected by filtration and purified by washing with

petroleum benzene. Yield (90%),1H NMR (400 MHz, CDCl3, 25°C): δ 10.92 (br. s, 1H, NH), 5.81 (s,

1H, ArH), 2.27 (s, 6H, CH3). 13

C NMR (100 MHz, CDCl3, 25°C): δ 144.36, 104.08, 12.24.

Synthesis of ligand H2L

Compound H2L was synthesized by refluxing p-benzoquinone with 3,5-dimethylpyrazole in 1,4-

dioxane under nitrogen atmosphere as in literature procedure.2 The product was further purified by

silica gel (60-120mesh) column chromatography using dichloromethane and ethyl acetate 7:3

mixtures. Yield (25%), Mp. 276-281 °C. 1H NMR (500 MHz, CDCl3, 25°C): δ 7.25 (s, 2H, OH), 7.04

(s, 2H, ArH), 5.89 (s, 2H, ArH), 2.28 (s, 6H, 2CH3), 1.67 (s, 6H, 2CH3). 13

C NMR (125 MHz, CDCl3,

25°C): δ 151.20, 145.74, 143.76, 120.46, 118.06, 107.02, 13.31, 10.72. ESI-MS (Methanol) m/z

(calc.): 299.20 (299.15) [C16H19N4O2+] Elemental analysis: Anal. Calcd. for C16H18N4O2: C, 64.41; H,

5

6.08; N, 18.78. Found: C, 64.36; H, 6.11; N, 18.53. UV-vis λmax/nm (ε/dm3 mol

−1 cm

−1) in CH3CN:

306 (4510), 222 (10025), 206 (9727). FT-IR (KBr) (νmax/cm−1

): 2933, 2624, 1557, 1499, 1226.

Synthesis of complex 1

0.298g (1.0 mmol) of H2L with 0.259g (1.0 mmol) of PdII(MeCN)2Cl2 were dissolved in acetonitrile

and heated to reflux under dark. After 16h the reaction mixture was cooled to room temperature and

concentrated on a rotary evaporator to get precipitation of the metal complex. The precipitation was

collected by filtration and washed with diethyl ether, which was further purified by crystallisation

from acetonitrile and ethyl acetate 5:2 mixture solution by slow evaporation method. Yield (95%),

Mp. (decomp.) >300 °C. 1H NMR (500 MHz, DMSO-d6, 25°C): δ 10.41 (s, 2H, OH), 7.32 (s, 2H,

ArH), 6.13 (s, 2H, ArH), 2.52 (s, 6H, 2CH3), 2.06 (s, 6H, 2CH3) (Figure S4). 13

C NMR (125 MHz,

DMSO-d6, 25°C): δ 180.27, 154.53, 147.02, 137.03, 136.82, 110.16, 14.06, 11.63 (Figure S5), ESI-

MS (Methanol) m/z (calc.): 403.14 (403.04) [C16H17N4O2Pd+], Elemental analysis: Anal. calcd. for

C16H18Cl2N4O2Pd: C, 40.4; H, 3.18; N, 11.78. Found: C 40.7 H, 3.35, N, 11.81. UV-vis λmax/nm

(ε/dm3 mol

−1 cm

−1) in CH3CN: 308 (9227). FT-IR (KBr) (νmax/cm

−1): 3360, 2362, 1554, 1507, 1294.

X-ray crystallography

A good quality brick red coloured single crystal was obtained from acetonitrile solution using the

method of slow evaporation. Single crystal X-ray diffraction study was carried out on the Agilent

Technologies Supernova diffractometer and measured at 300 K using Mo-Kα radiation (0.71073 Å).

An empirical multi-scan absorption correction was performed using spherical harmonics,

implemented in SCALE3 ABSPACK scaling algorithm. The integral values (from the instrument)

were refined in apex2 software where all non-hydrogen atoms were refined anisotropically by full

matrix least-squares on F2 to get the structure. The hydrogen atoms were calculated and fixed using

SHELXL-97 after hybridization of all non hydrogen atoms.3 Selected crystallographic parameters are

enlisted in Table S1. The crystallographic data of 1 has been deposited at the Cambridge

Crystallographic Data Centre as supplementary publication CCDC 996012. These data can be

obtained free of charge from the Cambridge Crystallographic Data Centre via

www.ccdc.cam.ac.uk/data_request/cif.

6

Table S1. Selected crystallographic parameters of 1.2H2O

1.2H2O

Empirical formula C16H20Cl2N4O4Pd

Formula weight 509.64

Temperature (K) 100(2)

Wavelength(Å) 0.71073

Crystal system Orthorhombic

space group Cmc2(1)

a (Å) 16.3889(10)

b (Å) 8.8163(3)

c (Å) 14.1318(4)

(deg.) 90

(deg.) 90

γ (deg.) 90

Volume (Å3) 2041.90(15)

Z, Calculated density (Mg/m3) 4, 1.651

F(000) 1120

Reflections collected / unique 2816 / 1921 [R(int) = 0.0266]

Max. and min. transmission 1.00000 and 0.93118

Goodness-of-fit on F2 1.072

Final R indices [I>2σ(I)] R1 = 0.0342, wR2 = 0.0752

R indices (all data) R1 = 0.0386, wR2 = 0.0798

Table S2. Selected bond lengths (Å) and angles (°) for 1.2H2O

Pd(1)-N(1) 2.024 N(1)-Pd(1)-N(1A)a 85.5

Pd(1)-Cl(1) 2.2827 N(1)-Pd(1)-Cl(1) 91.66

Cl(1)-Pd(1)-Cl(1A)a 91.20

a A = -x+1, y, z

7

General catalytic nitro reduction for aryl nitro substrates used for

optimization reactions

Nitro arene (1.0mmol), NaBH4 (4.0 mmol) were dissolved in10ml of ethanol followed by the addition

of 4.7 mg (1.0 mol %) of catalyst. After that the reaction mixture was refluxed according to the reflux

temperature of solvent under dark and completion was monitored by silica gel thin layer

chromatography. The solvent was evaporated under reduced pressure and re-dissolved in ethyl acetate

and washed two times with water. Further the product was purified by silica column chromatography

using 20% dichloromethane in petroleum benzene.

Optimization of complex 1 catalysed reduction of nitro arene reaction.

Table S3. Screening of solvent for aryl nitro reduction catalyzed by 1.a

NO2 NH2Pd-catalyst

NaBH4 , Solventreflux

Entry Solvent Isolated Yield (%)b

Time (min)

1 Ethanol >99 15

2 H2O >99 15

a Reaction conditions: 1.0 mmol nitrobenzene, 4.0 mmol sodium borohydride, 4.7 mg (1 mol %)

catalyst, solvent, reflux. b Isolated yields were reported after performed column chromatography.

Table S4. Screening of temperature for aryl nitro reduction of Nitrobenzene catalyzed by 1.a

NO2 NH2Pd-catalyst

NaBH4 , water , T oC

Entry Temperature(T oC) Isolated Yield (%)

b Time (min)

1 85 >99 15

2 60 >99 15

3 27 >98 20

a Reaction conditions: 1.0 mmol nitrobenzene, 4.0 mmol sodium borohydride, water , 4.7 mg (1 mol

%) catalyst, T °C. b Isolated yield were reported after column chromatography.

8

Table S5. Screening of catalyst loading for aryl nitro reduction of Nitrobenzene catalyzed by 1.a

NO2 NH2Pd-catalyst

NaBH4 , water, 27 oC

Entry Catalyst Loading

(mol %)

Isolated Yield (%)b Time (min)

1 1.0 >99 20

2 0.5 >99 20

3 0.25 >99 25

a Reaction conditions: 1.0 mmol nitrobenzene, 4.0 mmol Sodium borohydride, catalyst 1, water, 27°C.

b Isolated yields were reported after column chromatography.

Table S6. Catalytic ability of complex 1 over few other common Pd-compounds.a

NO2 NH2Pd-catalyst

NaBH4 , ethanol,

27oCNC NC

Entry Catalyst Catalyst loading

(mol % )

Isolated Yield

(%)[b]

Time (h)b

1 Pd(OAc)2 1.0 <30 6

2 PdCl2 1.0 <20 6

3 Pd(MeCN)2Cl2 1.0 <30 6

4 1 0.25 >99 0.17

a Reaction conditions: 1.0 mmol nitroarene, 4.0 mmol Sodium borohydride, catalyst 1, ethanol, 27°C.

b

Isolated yields were reported after column chromatography.

Representative procedure of catalytic reduction of nitroarenes substrates

1.0 mmol of nitroarene dissolved in 10ml of water followed by 0.152 g (4.0 mmol) NaBH4 and 1.2

mg (0.25 mol %) 1, were added to the reaction mixture at 27 °C and stirred vigorously. The

completion of the reaction was monitored by silica thin layer chromatography. After completion, the

reaction mixture was dried under reduced pressure and further purified by short silica column

chromatography (60-120 mesh) using proper ratio of dichloromethane in petroleum benzene as eluent.

The pure product was stored in desiccator under dark.

General catalytic Suzuki-Miyaura cross coupling reaction for aryl halide

substrates with phenyl boronic acid used for optimization reactions

Aryl halide (1.0 mmol), phenylboronic acid (1.5 mmol), base (3.0 mmol) and 2.3 mg (0.5 mol %) of

catalyst (complex 1) were kept in a single neck round bottom flask followed by 10ml solvent was

added to it. Now the reaction was performed at reflux temperature. After completion of the reaction,

9

the reaction mixture was dried under reduced pressure. Dissolve the reaction mixture in

dichloromethane and washed two times with water. The organic layer was dried over Na2SO4 and

purified through a short column chromatography (silica gel 60-120 mesh) using the appropriate

ratio of petroleum ether and dichloromethane to get pure biaryl.

Optimization of complex 1 catalysed Suzuki-Miyaura cross coupling

reaction

Table S7. Optimization of solvent for Suzuki-Miyaura cross coupling reaction of 4-bromo anisole with phenylboronic acid catalyzed by 1.a

Br

O

BOH

OH

O

+

Pd-cat (0.5mol%)

K2CO3, Solvent, reflux

Entry Solvent Isolated Yield (%)b

Time (h)

1 H2O < 10 3.0

2 Ethanol > 99 2.0

3 Dichloromethane 22 3.0

4 Toluene 48 3.5

5 1,4-Dioxane 26 3.5

6 Acetonitrile < 10 3.5

a Reaction conditions: 1.0 mmol 4-bromoanisole, 1.5 mmol phenylboronic acid, 0.5 mol% catalyst 1, 3

mmol K2CO3, solvent, reflux. b Isolated yields were reported after column chromatography

Table S8. Optimization of base for Suzuki-Miyaura cross coupling reaction of 4-bromo anisole with phenylboronic acid catalyzed by 1.a

Br

O

BOH

OH

O

+

Pd-cat (0.5 mol%)

base, ethanol, reflux

Entry Base Isolated Yield (%)b

Time (h)

1 K2CO3 >99 2.0

2 Cs2CO3 94 3.0

3 NaOMe 75 3.0

4 Et3N 40 3.0

5 KOH 65 3.0

a Reaction conditions: 1 mmol 4-bromoanisole, 1.5 mmol phenylboronic acid, 0.5 mol% catalyst 1, 3

mmol base, ethanol, reflux. b Isolated yields were reported after column chromatography

10

Table S9. Screening of catalyst loading for Suzuki-Miyaura cross coupling reaction of 4-bromoanisole with phenylboronic acid catalyzed by 1.a

Br

O

BOH

OH

O

+

Pd-cat

K2CO3, ethanol, reflux

Entry Catalyst Loading

(mol %)

Isolated Yield (%)b Time (h)

1 0.5 >99 2.0

2 0.25 >99 2.5

3 0.1 54 3.0

a Reaction conditions: 1 mmol 4-bromoanisole, 1.5 mmol phenylboronic acid, catalyst 1, 3 mmol

K2CO3, ethanol, reflux. b Isolated yields were reported after performed column chromatography.

Table S10. Screening of temperature for Suzuki-Miyaura cross coupling reaction of 4-bromoanisole with phenylboronic acid catalyzed by 1.a

Br

O

BOH

OH

O

+

Pd-cat (0.25 mol %)

K2CO3, T oC

Entry Temperature (T °C) Isolated Yield (%)

b Time (h)

1 80 >99 2.5

2 27 >99 4.5

a Reaction conditions: 1.0 mmol 4-bromoanisole, 1.5 mmol phenylboronic acid,0.25 mol% catalyst 1,

3.0 mmol K2CO3, ethanol. b Isolated yields were reported after column chromatography.

Representative procedure for Suzuki-Miyaura cross coupling reaction

Aryl halide (1.0 mmol), phenylboronic acid (1.5 mmol), potassium carbonate (3.0 mmol) and 1.2 mg

(0.25 mol %) of catalyst (complex 1) were kept in a single neck round bottom flask followed by

which 10ml ethanol was added to it. Now the reaction was performed at 27 °C. After completion of

the reaction, the reaction mixture was dried under reduced pressure and re-dissolved in

dichloromethane then washed for two times with water. The organic layer was dried over Na2SO4 and

purified through a short column chromatography (silica gel 60-120 mesh) using the appropriate ratio

of petroleum ether and dichloromethane to get the pure biaryl.

11

X

PdCl Cl

Pd0

II

II

OHHO

NN

N N

OO

NN

N N

Pd

OO

NN

N N

X

IIPd

OO

NN

N N

OCO2

IIPd

OO

NN

N N

Ar'

K2CO3

KClAr' B

OH

OH

B(CO3)2(OH)2

Ar'

Oxidative AdditionReductive Elimination

Transmetallation

Scheme S1. Proposed catalytic cycle for Suzuki-Miyaura cross coupling reaction by complex 1 in presence of base. The mechanistic pathway is similar to that known in literature.4

Table S11. Suzuki-Miyaura cross coupling reaction of aryl halides with Phenylboronic acid.a

ArX +

BOH

OH

Ar1(0.25mol%)

Entry Substrate (ArX) Product Isolated Yieldb (%) Time (h)

1

Br

H3COC

H3COC

98 2.3

2

Br

H3CO H3CO

95 4.5

12

3c

Cl

NC NC

43 20

4c

Cl

H3CO H3CO

40 22

5 N

Br

N

96 5.1

6

I

H3CO

H3CO

>99 1.2

7

I

H3C

H3C

>99 1.2

8

I

NO2

NO2

>99 1.0

9

Br

O2N

O2N

98 2.2

10

Br

NC

NC

98 2.5

a Reaction conditions: 1.0 mmol aryl halide, 1.5 mmol phenylboronic acid, 0.25 mol% catalyst 1, 3.0

mmol K2CO3, ethanol, 27 °C. b Isolated yields were reported after column chromatography.

c 2 mol%

catalyst 1, 3.0 mmol K2CO3, ethanol, 80 °C

General procedure for Syntheses of biaryl amines from nitro substituted

aryl halides and phenylboronic acid in one pot using catalyst 1

1.0 mmol of nitro substituted aryl halide, 1.5 mmol phenylboronic acid, 3.0 mmol K2CO3 were taken

in a single neck round bottom flask followed by addition of 15 ml of ethanol and 1.2 mg (0.25 mol %)

of catalyst at room temperature. The completion of the reaction was monitored by silica gel thin layer

chromatography. After that immediately 0.152 g (4.0 mmol) NaBH4 was added and stirred for another

1 h under dark. The solvent of the reaction mixture was evaporated under reduced pressure and the

residues redissolved in dichloromethane, washed two times with water. Finally the product was

purified by short silica (60-120 mesh) column chromatography using dichloromethane and petroleum

benzene mixture. The pure products were isolated and stored in desiccator under dark.

13

NO2

NO

NHOH

NH2

NaBH4

O

O

N

N

N

N

PdII

O

O

N

N

N

N

Pd0

OH

HO

N

N

N

N

PdII

NaBH4

O

O

N

N N

N PdII

O

O

N

N N

N Pd0

HO

OH

N

N N

N PdII

NaBH4

O

O

N

N

N

N

PdII

O

O

N

N

N

N

Pd0

OH

HO

N

N

N

N

PdII

NaBH4

O

O

N

N

N

N

PdII

O O

NN

NNPd

0

HO OH

NN

NNPdII

O

O

N

N

N

N

PdIIBr

O2N

H

O2N

NO2

Br

2H+, 2e-

2H+, 2e-

2H+, 2e-

+ H2OH2O +

Cl Cl

Scheme S2. Proposed dehalogenation and nitroarene reduction mechanism by catalyst 1 using

1-bromo-4-nitrobenzene as a model substrate. The complex is dipositively charged when the

palladium is +2 oxidation state.

14

Figure S1. 1H NMR spectrum of the reaction between iodobenzene (0.018mmol)

and NaBH4 (0.018 mmol) in presence of catalyst 1 (0.003 mmol) in methanol-D4

at 25 °C. More than 90% conversion has occurred within 4-5 min since the

spectra shows presence of only ca. 6% substrate (iodobenzene).

Figure S2. 1H NMR spectrum of reaction mixture of iodobenzene (0.018mmol)

and NaBH4 (0.018 mmol) in presence of 1 (0.003 mmol, to have sufficient

concentration in 1H NMR). Solvent is methanol-D4, spectrum recorded at 25 °C

and only the relevant region was scanned for better signal to noise ratio.

15

Figure S3. 1H NMR of 0.03 mmol of 4-nitrobenzonitrile, 0.24 mmol NaBH4, 0.25 mol% catalyst 1

in D2O. 1,4-dioxane was used for reference.

1H and 13C NMR data of Suzuki-Miyaura product 4-methoxybiphenyl. 1H NMR (CDCl3, 400 MHz, 25 °C) 7.55 (m, 4H, ArH), 7.43 (m, 2H, ArH),

7.31 (m, 1H, ArH), 6.99 (m, 2H, ArH), 3.86 (s, 3H, CH3) (Figure S6). 13

C NMR (CDCl3, 100 MHz,

25 °C) 159.25, 140.94, 133.89, 128.85, 128.29, 126.87, 126.78, 114.31, 55.46 (Figure S7).

4-methylbiphenyl. 1H NMR (CDCl3, 400 MHz, 25 °C) 7.60 (d, J = 9.44 Hz, 2H, ArH), 7.52 (d, J

= 7.6 Hz, 2H, ArH), 7.4 (m, 2H, ArH), 7.35 (m, 1H, ArH), 7.27 (m, 2H, ArH), 2.43 (s, 3H, CH3)

(Figure S8). 13

C NMR (CDCl3, 100 MHz, 25 °C) 141.28, 138.47, 137.15, 129.61, 128.84, 127.10,

21.24 (Figure S9).

4-acetylbiphenyl. 1H NMR (CDCl3, 400 MHz, 25 °C) 8.02 (d, J = 8.4 Hz, 2H, ArH), 7.68 (d, J =

8.4 Hz, 2H, ArH), 7.61 (m, 2H, ArH), 7.47 (m, 2H, ArH), 7.42 (m, 1H, ArH), 2.64 (s, 3H, CH3)

(Figure S10). 13

C NMR (CDCl3, 100 MHz, 25 °C) 197.97, 145.90, 139.96, 135.92, 129.07, 129.08,

128.36, 127.38, 127.35, 26.81 (Figure S11).

4-nitrobiphenyl. 1H NMR (CDCl3, 400 MHz, 25 °C) 8.28 (d, J = 9.16 Hz, 2H, ArH), 7.72 (d, J =

8.4 Hz, 2H, ArH), 7.62 (m, 2H, ArH), 7.46 (m, 3H, ArH) (Figure S12). 13

C NMR (CDCl3, 100 MHz,

25 °C) 147.75, 147.17, 138.87, 129.28, 129.04, 127.92, 127.5, 124.23 (Figure S13).

16

4-cyanobiphenyl. 1H NMR (CDCl3, 400 MHz, 25 °C) 7.67 (m, 4H, ArH), 7.58(m, 2H, ArH), 7.48

(m, 2H, ArH), 7.42 (m, 1H, ArH) (Figure S14). 13

C NMR (CDCl3, 100 MHz, 25 °C) 145.79, 139.28,

132.72, 129.24, 128.79, 127.86, 127.35, 119.1, 111 (Figure S15).

2-phenylpyridine. 1H NMR (CDCl3, 400 MHz, 25 °C) 8.70 (m, 1H, ArH), 7.99 (m, 2H, ArH),

7.73 (m, 2H, ArH), 7.50 (m, 3H, ArH), 7.23 (m, 1H, ArH) (Figure S16). 13

C NMR (CDCl3, 100 MHz,

25 °C) 157.6, 149.77, 139.49, 136.91, 129.08, 128.87, 127.04, 122.24, 120.74 (Figure S17).

3-nitrobiphenyl. 1H NMR (CDCl3, 500 MHz, 25 °C) 8.46 (m, 1H, ArH), 8.19 (m, 1H, ArH), 7.9

(m, 1H, ArH), 7.64-7.61 (m, 3H, ArH), 7.52-7.43 (m, 3H, ArH) (Figure S18). 13C NMR (CDCl3, 125

MHz, 25 °C) 148.88, 143.03, 138.82, 133.19, 129.85, 129.31, 128.68, 127.31, 122.18, 122.11

(Figure S19).

1H and 13C NMR data of nitro reduction product

Aniline. 1H NMR (CDCl3, 400 MHz, 25 °C) 7.16 (m, 2H, ArH), 6.77 (m, 1H, ArH), 6.69 (m, 2H,

ArH), 3.35 (br. s, 2H, NH2). (Figure S20). 13

C NMR (CDCl3, 100 MHz, 25 °C) 146.41, 129.41,

118.73, 115.26 (Figure S21).

4-aminophenol. 1H NMR (DMSO-D6, 400 MHz, 25 °C) 6.45 (d, J = 8.56 Hz, 2H, ArH), 6.38 (d, J

= 8.56 Hz, 2H, ArH), 4.35 (br. s, 2H, NH2). (Figure S22). 13

C NMR (DMSO-D6, 100 MHz, 25 °C)

149.10, 141.12, 115.98, 115.66. (Figure S23).

4-cyanoaniline. 1H NMR (CDCl3, 400 MHz, 25 °C) 7.41 (d, J = 8.36 Hz, 2H, ArH), 6.62 (d, J =

11.48 Hz, 2H, ArH), 4.13 (br. s, 2H, NH2). (Figure S24). 13

C NMR (CDCl3, 100 MHz, 25 °C)

150.45, 133.96, 120.20, 114.58, 100.50. (Figure S25).

4-(pyridin-4-ylmethyl)aniline. 1H NMR (CDCl3, 500 MHz, 25 °C) 8.46 (d, J = 4.56 Hz, 2H,

ArH), 7.10 (d, J = 4.56 Hz, 2H, ArH), 6.94 (d, J = 7.64 Hz, 2H, ArH), 6.63 (d, J = 8.4 Hz, 2H, ArH),

3.86 (s, 2H, CH2), 2.92 (br. s, 2H, NH2). (Figure S26). 13

C NMR (CDCl3, 125 MHz, 25 °C) 151.37,

149.28, 145.01, 129.81, 128.59, 124.17, 115.38, 40.40. (Figure S27).

4-chloro-1,2-diaminobenzene. 1H NMR (CDCl3, 500 MHz, 25 °C) 6.67 (d, J = 2.5 Hz, 1H,

ArH), 6.66 (m, 1H, ArH), 6.65 (d, J = 8.5 Hz, 1H, ArH), 3.23 (br. s, 1H, NH2). (Figure S28). 13

C

NMR (CDCl3, 125 MHz, 25 °C) 136.25, 133.18, 124.94, 119.74, 117.67, 116.37. (Figure S29).

1H and 13C NMR data of tandem type reaction product 4-aminobiphenyl. 1

H NMR (CDCl3, 400 MHz, 25 °C) 7.34 (m, 5H, ArH), 7.53 (m, 4H, ArH).

(Figure S30). 13

C NMR (CDCl3, 100 MHz, 25 °C) 144.79, 129.58, 129.06, 123.17, 120.52, 116.25,

115.47, 115.26. (Figure S31).

3-aminobiphenyl. 1H NMR (CDCl3, 500 MHz, 25 °C) 7.56 (m, 2H, ArH), 7.42 (m, 2H, ArH),

7.33 (m, 1H, ArH), 7.25 (m, 1H, ArH), 7.04 (m, 1H, ArH), 6.99 (m, 1H, ArH), 6.75 (m, 1H, ArH).

(Figure S32). 13C NMR (CDCl3, 125 MHz, 25 °C) 145.35, 142.69, 141.32, 129.87, 128.79, 127.43,

127.25, 118.76, 114.94, 114.77. (Figure S33).

17

Figure S4. 1H NMR of 1 in DMSO-D6

Figure S5. 13C NMR of 1 in DMSO-D6

18

Figure S6. 1H NMR of 4-methoxybiphenyl in CDCl3

Figure S7. 13C NMR of 4-methoxybiphenyl in CDCl3

19

Figure S8. 1H NMR of 4-methylbiphenyl in CDCl3

Figure S9. 13C NMR of 4-methylbiphenyl in CDCl3

20

Figure S10. 1H NMR of 4-acetylbiphenyl in CDCl3

Figure S11. 13C NMR of 4-acetylbiphenyl in CDCl3

21

Figure S12. 1H NMR of 4-nitrobiphenyl

Figure S13. 13C NMR of 4-nitrobiphenyl in CDCl3

22

Figure S14. 1H NMR of 4-cyanobiphenyl in CDCl3

Figure S15. 13C NMR of 4-cyanobiphenyl in CDCl3

23

Figure S16. 1H NMR of 2-phenylpyridine in CDCl3

Figure S17. 13C NMR of 2-phenylpyridine in CDCl3

24

Figure S18. 1H NMR of 3-nitrobiphenyl in CDCl3

Figure S19. 13C NMR of 3-nitrobiphenyl in CDCl3

25

Figure S20. 1H NMR of aniline in CDCl3

Figure S21. 13C NMR of aniline in CDCl3

26

Figure S22. 1H NMR of 4-aminophenol in DMSO-D6

Figure S23. 13C NMR of 4-aminophenol in DMSO-D6

27

Figure S24. 1H NMR of 4-cyanoaniline in CDCl3

Figure S25. 13C NMR of 4-cyanoaniline in CDCl3

28

Figure S26. 1H NMR of 4-(pyridin-4-ylmethyl)aniline in CDCl3

Figure S27. 13C NMR of 4-(pyridin-4-ylmethyl)aniline in CDCl3

29

Figure S28. 1H NMR of 4-chloro-1,2-diaminobenzene in CDCl3

Figure S29. 13C NMR of 4-chloro-1,2-diaminobenzene in CDCl3

30

Figure S30. 1H NMR of 4-aminobiphenyl in CDCl3

Figure S31. 13C NMR of 4-aminobiphenyl in CDCl3

31

Figure S32. 1H NMR of 4-aminobiphenyl in CDCl3

Figure S33. 13C NMR of 3-aminobiphenyl in CDCl3

32

References.

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Foces-Foces, F. Hernandez Cano, J. Elguero and R. Sastre, Journal of the American Chemical Society, 1990, 112, 747-759.

3. G. M. Sheldrick, International Union of Crystallography, Crystallographic Symposia, 1991, 5, 145-157.

4. K. Matos and J. A. Soderquist, Journal of Organic Chemistry, 1998, 63, 461-470. 5. A. K. Shil and P. Das, Green Chem., 2013, 15, 3421-3428. 6. K. Layek, M. L. Kantam, M. Shirai, D. Nishio-Hamane, T. Sasaki and H. Maheswaran, Green

Chem., 2012, 14, 3164-3174.