981

Reference Data

Table 2. "C,'H and 13C,"F NMR coupling constants (Hz) in compounds 1-11

Compound 'J(CF,) 5J (C-2) 3J(C-4) 'J(C-5) 3J(C-6) *Jw

"J(C.CF,)

1 276.5 - - 38.5 1.1 ' J , SH = 2.5; 3J3. s H = 6.2 3J,, SH = 4.0

3 275.4 0.7 1 .o 32.7 1.1 3J,, M e = 4.0 4 275.4 0.7 - 31.2 1.1 3J2, Me = 4.0 5 276.8 0.5 - 31.6 1 .o 6 276.5 0.7 0.9 32.7 1 .o 7 275.9 0.5 - 31.2 1.1 8 276.1 - - 30.9 1.1 9 275.8 0.7 0.5 31.4 1.1

10 276.8 - - 31.2 1 .o 11 277.0 0.7 0.5 31.2 1 .o

2 276.5 - - 31.2 1.1 3J,, M e = 5.1

- - - -

- - -

observed for C-2 in all 2-thiosubstituted corn- pounds, while substantial downfield shifts of C-4 (150.37-1 52.61) were observed only in mono-thiosubstituted 1, 2 and 5. Comparison of the C-3 and C-5 signals (see Table 1) indi- cates that in all of 1-11 C-5 resonates at higher field, thus being in agreement with the

Table 2), so 2J(C-5,CF,) and 'J(C-6,CF3) may be useful for the structure elucidation of relative trifluoromethyl-substituted pyridines.

References - - - directions of the ips0 substitution effects of CI and CF, groups found for benzenes." Exter- nal *J(C-5,CF3) and some longer range coup- lings for C-2, C-4 and C-6 were observed in all of 1-11. We can note that, in general, ,J(C-6,CF3) in 1-11 is larger than the corre-

1 . B. Iddon, H. Suschitzky, A. M. Thomp- son and E. Ager, J. Chem. SOC., Perkin Trans. 1 2300 (1974).

2. B. Iddon. A. G. Mack, H. Suschitzky, J. A. Taylor and B. J. Wakefield, J. Chern. SOC.. Perkin Trans. 1 1370

sponding 'J(C-4,CF3) and 'J(C-5,CF3) (see ( 1 980).

3. M. Gelbcke, R. Grimee, R. Lejeune, L. Thunus and J. V. Dejardin, Bull. SOC. Chim. Belg. 92, 39 (1 983).

4. A. Shank, J. M. Dereppe and M. Van Meerche, Bull. SOC. Chirn. Belg. 92, 199 (1983).

5. A. M. Sipyagin, S. V. Paltsun, A. V. Piyuk, N. N. Sveshnikov, V. I . Koz- lovsky and 2. G. Aliev, Zh. Org. Khim. 29, 1872 (1 993).

6. A. M. Sipyagin, V. V. Kolchanov and N. N. Sveshnikov, Tetrahedron Lett. 35, 31 47 (1 994) ; Khim. Geterotsikl. Soedin. 660 (1994).

7. A. M. Sipyagin and B. V. Kunshenko, Khim. Geterotsikl. Soedin. 657 (1 994).

8. Y. Kobayashi and 1. Kumadaki, 3. Chem. SOC., Perkin Trans. 1 661 (1980); L. D. Shustov, L. N . Nikol- enko and T. M. Senchenkova, Zh. Obshch. Khim. 53, 103 (1983); M. Tordeux, B. Langlois and C. Waksel- man, J. Chern. SOC., Perkin Trans. 1 2293 (1 990) ; M. A. McClinton and D. A. McClinton, Tetrahedron 48, 6555 (1992); A. Mukherjee, S. A. M. Duggan and W. C. Agosta, J. Org. Chem. 59 ,178 (1994).

9. I . B. Cook, Aust. J. Chem. 42, 1493 (1989).

10. D. F. Ewing, Org. Magn. Reson. 9,499 (1979).

Received 2 March 1995; Accepted 15 April 1995

Substituent-Induced Chemical Shifts of Aromatic Carbon Centres in a Series of Non-Acetylated and Peracetylated Puru- Substituted Aryl 2-N-acetamido-2-deoxy- &D-glucopyranosides

RENE ROY Department of Chemistry, University of Ottawa, Ottawa, Ontario, KIN 6N5, Canada FRANCOIS D. TROPPER Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720, USA ANTONY J. WILLIAMS (to whom corre- spondence should be addressed) Eastman Kodak Company, Analytical Technology Division, Rochester, New York 14650-2132, USA

The additive behaviour generally observed for the substituent-induced chemical shifts (SCS) for disubstituted benzenes was

examined for a series of aryl 2-N-aceta- mido-2-deoxy-fi-D-glucopyranosides having a wide range of para substituents with varying possible electronic contributions. The SCS values associated with non- acetylated and peracetylated glucoside rings in para-substituted aryl 2-N- acetamido -2 - deoxy - p- D - gl ucopyranosides were calculated. The additive nature of SCS analysis for para-substituted systems was shown to hold for the meta and para positions but the very small change in chemical shifts for the ortho positions pre- cluded attempts at analysis of these data. The observation of a good correlation for the ips0 carbons for the acetylated com- pounds compared with a poor correlation for the same site in the non-acetylated compounds is not well understood.

KEY WORDS NMR; substituent-induced chemical shifts; 2-N-acetamido-2-deoxy- P- D-glucopyranosides

INTRODUCTION

Aryl glycosides are commonly found in nature and a number of these compounds

have been shown to demonstrate medicinal properties. Applications of aryl glycosides include their use as chromogenic substrates in enzymology' and as inhibitors of sugar- lectin interactions.* We have been engaged in the studies of fundamental aspects of lectin- carbohydrate binding interactions at the molecular level. For example, it has been shown that p-nitrophenyl-2-N-acetamido-2- deoxy-p-o-glucopyranoside is an inhibitor of haemagglutination of human type A red blood cells and wheat germ (Triticum oulgaris) lectin (WgA).2 To investigate the possible formation of charge-transfer com- plexes by aromatic stacking within the binding site of the WGA, we have synthe- sized a series of 2-N-acetamid0-2-deoxy-p-~- glucopyranosides having a wide range of porn substituents with varying possible electronic contribution^.^,^ We have previously rigor- ously assigned all 'H and I3C chemical shifts for the series of para-substituted aryl 2-N- acetamido-2-deoxy-~-o-glucopyranosides5 1 and 2. In this work, we have examined whether the additive behaviour generally observed for the substituent-induced chemi- cal shifts6.' (SCS) for disubstituted benzenes is also observed for these carbohydrate systems.

CI 1995 by John Wiley & Sons, Ltd.

982

Reference Data

EXPERIMENTAL

All compounds were synthesized as described e l ~ e w h e r e . ~ . ~ All NMR measure- ments were conducted at ambient tem- perature (23°C) using a Varian XL-300 spectrometer and a 5 mm ',C, 'H switchable probe. 'H and I3C spectra were measured at concentrations of 6.7 mg ml-' and 5.46 x M, respectively, for all samples. CDCI, was used to dissolve the acetylated glycosides while DMSO-d, was used as the solvent for the glycosides with free hydroxyl groups. The residual solvent resonances were used as chemical shift references for the 'H spectra while the central resonances of the deuterated solvent multiplets were used to reference the I3C spectra.

'H spectra were acquired at a resonance frequency of 299.943 MHz using a 3000 Hz spectral window, exci:ed with a 33" pulse; 16

K data points were acquired prior to Fourier transformation at 32 K points. Proton- decoupled ',C spectra were acquired at 75.43 MHz using a 16502 Hz spectral window, excited with a 38" pulse; 16 K data points were acquired, and zero filling to 64 K points was applied prior to Fourier transformation.

RESULTS AND DISCUSSION

Substituent-induced chemical shift (SCS) values are generally additive for simple para- and meta-substituted benzenes and have been successfully used to predict I3C chemical shifts for a variety of substituted aromatic compounds including phenols and phen- oxides,' methyl benzoates' and benzonitri- les,lo for example. We were curious to evaluate if the additivity theory of substituent effects would also be observed for the title

compounds which have a bulky glycosyl unit and which exhibit different solution proper- ties when the glycosyl unit is acetylated (R = Ac) or non-acetylated (R = H). Thus, by using the aryl 13C chemical shifts for glyco- sides with X = H below as a reference, the SCS values for the glycosyl moiety, in both peracetylated and non-acetylated forms, were determined. With these values, the "C chemical shifts of aromatic carbon centres in a series of para-substituted glycosides were calculated using known''." SCS values for monosubstituted benzenes and compared with observed values. Thus, after comparison with the chemical shift of unsubstituted benzene in CDCI,, the SCS values for I and 2, where X = H, relative to benzene, were evaluated as being Zi,, = 29.1, 28.7, Za,,ho = -12.1, - 11.9, Z,,,, = 1.1, 1.0 and Z,,a = - 6.5, - 5.4 ppm, respectively. Interestingly, the Z(X) values are very similar for both

~~ ~~

Table 1. Calculated versus observed aryl "C

X para-substituent

NH,

C"3 OCH,

H F CI CHO CN NO2

z o

-9.6 -7.8 -3.0 0

-4.4 -2.0 3.8 5.0 6.2

6C,,,, Calc

148.0 149.8 154.6 157.6 153.2 155.6 161.4 162.6 163.8

Found

149.0 154.5 155.5 157.6 158.9 156.3 162.1 160.6 160.3

chemical shifts (ppm) for non-acetylated glycosides 1 in DMSO-d,

6Cor,,, 6Cme,, 6C,,,, Z, Calc Found z, Calc Found Z P Calc

0.6 1 .o 0.7 0 0.9 1 .o 0.5 1.4 1.3

1 1 7.0 1 1 7.4 117.1 1 1 6.4 1 1 7.3 1 1 7.4 1 1 6.9 117.8 117.7

1 1 4.5 114.5 1 1 6.4 1 1 6.4 1 1 5.8 1 1 8.2 1 1 6.5 1 1 7.1 1 1 6.6

-14.1 -14.4 -0.1

0 -14.4 0.2 1.2 4.1

-4.3

1 1 5.3 1 1 5.0 129.3 129.4 1 1 5.0 129.6 130.6 133.5 125.1

1 18.0 1 1 7.8 129.7 129.4 1 1 8.0 129.2 131.7 134.2 125.8

20.2 142.2 31.4 151.4 9.3 131.3 0 122.0 35.1 157.1 6.4 128.4 8.2 130.2

-15.5 104.5 20.6 142.6

~

Found

143.8 151.6 130.8 122.0 153.9 125.8 130.7 104.3 141.8

Table 2. Calculated versus observed aryl chemical shifts (ppm) for peracetylated glycosides 2 in CDCI,

X para-substituent Z, Calc Found Z, Calc Found ZP Calc Found zn

6c,p50 6CO,,hO 6Cmeta

NH, -9.6 147.6 149.5 0.6 116.8 118.8 -14.1 115.4 115.9 20.2 OCH, -7.8 149.4 151.1 1.0 117.2 118.6 -14.4 115.1 114.5 31.4

H 0 157.2 157.2 0 116.2 116.2 0 129.5 129.5 0 F -4.4 152.8 154.8 0.9 117.1 118.6 -14.4 115.1 115.8 35.1 CI -2.0 155.2 155.5 1.0 117.2 118.4 0.2 129.7 129.9 6.4 CHO 3.8 161.0 161.5 0.5 116.7 116.7 1.2 130.7 131.7 8.2

NO2 6.2 163.4 - a 1.3 117.5 -a -4.3 125.2 -a 20.6

CH, -3.0 154.2 155.0 0.7 116.9 116.9 -0.1 129.4 129.9 9.3

CN 5.0 162.2 160.0 1.4 117.6 117.2 4.1 133.6 133.9 -15.5

a Insoluble in CDCI,.

6Coer.

143.3 154.5 132.4 123.1 158.2 129.5 131.3 107.6 143.7

Calc. Found

142.3 155.6 132.6 123.1 161 .I 128.2 131.9 105.5 -

Table 3. Linear least-squares analysis correlation coefficients (r') for I3C substituent induced chemical shifts in glycosides 1 and 2

Cmso c,,,,, c,,,, COB,*

Non-acetylated glycosides 1 0.573 - 0.992 0.991 Acetylated glycosides 2 0.965 - 0.984 0.997

983

Reference Data

1 R=H

- 2 R=Ac X = NH,,CH,, OCH,, H, F, C1, CHO, CN, NO,

acetylated and non-acetylated glycosides in where Z ( X ) is the predetermined SCS of the the two different solvent systems. corresponding monosubstituted benzene

Since SCS parameters are generally addi- derivative, in ppm. tive, we expected that the aromatic carbon Tables I and 2 list the calculated and chemical shifts determined experimentally for experimental "C chemical shifts determined each different phenyl ring substituent in gly- for both the non-acetylated and peracetylated cosides 1 and 2 would correlate well with glycosides for each of nine substituents inves- those calculated according

1 (R = H)

C,,, 157.6 + Zpora(X)

(-ortho 1 16.4 + Zrne,AX)

cmeca 129.4 Zorrhn(X)

_. tigated. Results from a linear least-squares analysis of these data are given in Table 3.

By using the SCS values in an additive fashion, the calculated chemical shifts of all

57.2 + ZPa,,JX) aromatic carbon centres in the non- acetylated glycosides are in excellent agree- ment with observed values for the meta and

2 (R = Ac)

+ z r n m ( x )

29.5 + zonho(~) para sites where the chemical shifts vary over ranges of ca. 15 and 50 ppm, respectively

C,,,, 122.0 + Z,,,(X) 123.1 + Z,,,(X) (Figs 1 and 2). However, the correlation for

M e t a - c a r b o n s 110

110 1 2 0 130 1

Observed Chemical Shift (pprn)

Figure 1.

the ipso site (Fig. 3) is poor, and for the ortho position no correlation is observed. It might be expected that for the ortho position the correlation would be poor since the chemical shift range is very small (ca. 1 ppm) and correlations for ortho positions have long been known to generally fail.13 This argu- ment is not valid, however, for the ips0 posi- tion since a similar distribution in chemical shift range is observed for C,,,, resonances.

For the peracetylated glycosides, the corre- lations for the meta and para substitution sites are also excellent. As before, the ortho position shows no correlation. However, in this case the correlation exhibited for the ipso position is much improved.

CONCLUSION

The SCS values associated with the non- acetylated and peracetylated glycoside rings in para-substituted aryl 2-N-acetamido-2- deoxy-B-o-glucopyranosides were calculated. The additivity theory of SCS for predicting I3C chemical shifts of aromatic carbons is observed for the meta and para positions. The observation of a good correlation for the ips0 carbons for the peracetylated glycosides com-

0 Glycosides 1 (R=H)

Para-cai pbo

165

P 160 P

= fi VI

- 1 - .$ 155 8 .v

9 150 I

u - (3

145 145 150 155 160 1 6 5

Observed Chemical Shift (ppm)

Figure 3.

100 . , . , . , . , . , . , ,

100 110 120 130 140 1 5 0 160 1

Observed Chemical Shifts (ppm)

Figure 2.

0

984

Reference Data

pared with a poor correlation for the same site in the non-acetylated glycosides is not well understood but may be due to confor- mational effects around the glycosidic linkage, solutesolute or solute-solvent association or electronic effects due to changes in electron density within the carbo- hydrate ring between the peracetylated and non-acetylated systems.

~ ~~~

References 1. J. A. Cabezas. A. Realero and P.

Functions and Applications in Biology and Medicine. Academic Press,

3. R. Roy, F. D. Tropper and A. J. Wil-

4. R. Roy and F. D. Tropper, Synth.

5. R. Roy, F. D. Tropper and A. J. Wil-

9.

Orlando (1986) . 10.

liams, Can. J. Chem. 69, 81 7 (1 991 ).

Commun. 2 0 , 2 0 9 7 (1 990).

liams, Magn. Reson. Chem. 29, 8 5 2 12 .

6 . P. C. Lauterbur, J . Am. Chem. SOC. 83, 1846 (1961). 13 .

7. G. L. Nelson, G. C. Levy and J. D, Car- gioli, J. Am Chem. SOC. 94, 3089 (1 972) .

11.

(1 991 ) .

M. Budesinsky and 0. Exner, Magn. Reson. Chem. 2 7 , 5 8 5 (1 989) . M. Budesinsky and 0. Exner, Magn. Reson. Chem. 27, 27 (1 989) . R. J. Abraham, J. Fisher and P. J. Loftus, Introduction to NMR Spec- troscopy, pp. 24-28. Wiley, New York (1 988). E. Breitmaier and W. Voelter. Carbon- 13 NMR Spectroscopy, 3rd ed., pp. 258-261. VCH, Weinheim (1987) . J. Bromilow, R. T. C. Brownlee, D. J. Craik, M. Sadek and R. W. Taft, J. Org. Chem. 4 5 , 2 4 2 9 (1 980).

Calvo, Int. J . Biocheh. 15, 2 4 3 8. F. Guillaume, J. P. Seguin, L. Nadjo, (1 983) . R . Uzan, F. Membrey and J. P.

stein (Eds), The Lectins, Properties, 1139 (1984). (revised) 26 February 1995. 2. I . E. Liener, N. Sharon and I . J. Gold- Doucet, J. Chem. SOC., Perkin Trans. 2 Received 7 September 1994; accepted

"'Rh chemical shifts and trans influence of ligands in rhodoximes and or- ganorhodoximes*

M. LUDWIG Institut fur Anorganische Chemie der Martin-Luther-Universitat Halle-Wittenberg, Weinbergweg 16, D-06120 Halle, Germany

Department of Chemistry, Royal Institute of Technology, S-10044 Stockholm, Sweden D. STEINBORN (to whom correspondence should be addressed) Institut fur Anorganische Chemie der Martin-Luther-Universitat Halle-Wittenberg, Weinbergweg 16, D-06120 Halle, Germany

L. OHRSTROM

The lo3Rh NMR chemical shifts of rho- doximes [Rh(dmgH),(PPh,)X] (1) and organorhodoximes [Rh (dmg H ) ,( L) R] (2, L = PPh,; 3, L = PMe,; 4, L = P(OPh),; 5, L = SMe,; 6, L = py) were measured with a wide range of anionic ligands X, organo groups R and axial ligands L. The chemical shifts 6(lo3Rh) in the halide complexes 1 show the 'normal halogen dependence' (CI > Br > I ) . 6 ( lo3Rh) in 2-6 depends on the axial base L in the order py > SMe, > PPh, > P(OPh), o PMe, and in 2 on the organo group R in the order Et = Me < "Pr < CH,Ph o CH,OMe < CH,Br < CH,CI < 'Pr < Cy < CH=CH, < CH,SiMe, < 'Bu < cis-CH=CHPh =cis-

* Investigations on Electronic Influence of Organyl Ligands, Part XII. For Part XI, see Ref. 2b.

CH=CHPr < Ph o C Z C P h < CPr=CH,. The coupling constants 1J('03Rh,3'P) in 2 reflect the (NMR) trans influence of R. There is a strong correspondence between the NMR trans influence and the structural trans influence, a s indicated by the bond lengths d ( Rh- P) .

KEYWORDS NMR; lo3Rh; , 'P; 13C; rho- doximes; organobis(dimethylg1yoximato) rhodium complexes; trans influence; coupling constants.

INTRODUCTION

NMR spectroscopic investigations are an invaluable approach to acquiring a deeper insight into the electronic structure of com- plexes when series of complexes with system- atic variations of ligands are studied and when both the central atom and ligator atoms exhibit nuclear spins t = 1/2, as is the case of rhodoximes [Rh(dmgH),(L)X] and

(dmgH, = dimethylglyoxime, L = PR;, P(OR'), as axial base, X = anionic ligand, R = organo ligand).' The coupling constants 1J(103Rh,3'P) reflect the trans influence of the

organorhodoximes CRh(dmgH),(L)Rl

X I

PPh,

1

For X see Table 1

anionic ligand X and the organo ligand R.' Here we report on an investigation of losRh chemical shifts and their dependence on L, R and X.

RESULTS AND DISCUSSION

The "'Rh NMR chemical shifts were measured for the compounds [Rh(dmgH),(PPh,)XI (1) and [Rh(dmgH),(L)R] (24) with a wide range of anionic ligands X, organo groups R and axial ligands L (see Scheme 1 and Table 1). The range of Io3Rh chemical shifts spans only about 900 ppm, which is small if we take into account the whole range of '03Rh shifts of about 12000 p p m 3

6(Io3Rh) in the halide complexes la+ (Cl > Br > I) corresponds to the ability to shield rhodium in the order CI < Br < I, reflecting a 'normal halogen dependence' (NHD) for rhodium chemical shifts. The ratio of the difference A(Cl,Br)/

[6('03Rh)x=,, - 6('03Rh)x=i] amounts to 0.36 and is in good agreement with the values for other rhodium compound^.^ Further, the observed '03Rh chemical shifts of la- show

A(CI/I) = [6('03Rh),=,, - 6('03Rh)x=,,] /

?

L

2 - 6

For L and R see Table 1 Scheme 1

0 1995 by John Wiley & Sons, Ltd.