Total spontaneous resolution of a cyanoguanidine showing only conformational chirality

Chemical Communications

Volumn , Issue 1, 2000, Pages 61-62

  Cunningham, Ian D ^a   Coles, Simon J ^b   Hursthouse, Michael B ^b  

^a UNIVERSITY OF SURREY   (United Kingdom)

^b UNIVERSITY OF SOUTHAMPTON   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

GUANIDINE DERIVATIVE; NITRILE;

ARTICLE; CHEMICAL REACTION; CHIRALITY; CONFORMATION; NUCLEAR MAGNETIC RESONANCE; REACTION ANALYSIS; TEMPERATURE; X RAY CRYSTALLOGRAPHY;

EID: 0034614516     PISSN: 13597345     EISSN: None     Source Type: Journal    
DOI: 10.1039/a907518f     Document Type: Article

References (26)

1. E. L. Eliel and S. H. Wilen, Stereochemistry of Organic Compounds, Wiley, New York, 1994, ch. 7.
2. K. R. Wilson and R. E. Pincock, J. Am. Chem. Soc., 1975, 97, 1474; R. Kuroda and S. F. Mason, J. Chem., Soc., Perkin Trans. 2, 1981, 167.
3. K. R. Wilson and R. E. Pincock, J. Am. Chem. Soc., 1975, 97, 1474; R. Kuroda and S. F. Mason, J. Chem., Soc., Perkin Trans. 2, 1981, 167.
4. G. R. Desiraju, Angew. Chem., Int. Ed. Engl, 1995, 34, 2311; G. R. Desiraju, Crystal Engineering. The Design of Organic Solids, Materials Science Mongraphs 54, Elsevier, Amsterdam, 1989.
5. G. R. Desiraju, Angew. Chem., Int. Ed. Engl, 1995, 34, 2311; G. R. Desiraju, Crystal Engineering. The Design of Organic Solids, Materials Science Mongraphs 54, Elsevier, Amsterdam, 1989.
6. Defined as absolute asymmetric synthesis, see M. Sakamoto, Chem. Eur. J., 1997, 3, 684 and references therein.
7. L. Addadi and M. Lahav, Origins of Optical Activity in Nature, ed. D. C. Walker, Elsevier, Amsterdam, 1979, ch. 14; E. L. Eliel and S. H. Wilen, Stereochemistry of Organic Compounds, Wiley, New York, 1994, ch. 6.
8. L. Addadi and M. Lahav, Origins of Optical Activity in Nature, ed. D. C. Walker, Elsevier, Amsterdam, 1979, ch. 14; E. L. Eliel and S. H. Wilen, Stereochemistry of Organic Compounds, Wiley, New York, 1994, ch. 6.
9. A racemic compound is where a particular chiral molecule is partnered within the crystal by its enantiomer. A conglomerate is a mixture of crystals, each of one or the other chiral form; J. Jacques, A. Collet and S. H. Wilen, Enantiomers, Racemates and Resolutions, Wiley, New York, 1981.
10. See ref 4.With a conglomerate where the molecules owe their chirality only to conformational differences, selection of a single homochiral crystal followed by a suitable transformation can yield a configurationally stable chiral product and qualify as an absolute asymmetric synthesis. However, a pedant might point to the requirement of a chiral human auxilliary!
11. See for example, T. Suzuki, T. Fukushima, Y. Yamashita and T. Miyashi, J. Am. Chem. Soc., 1994, 116, 2793; A. Sekine, K. Hori, Y. Ohashi, M. Yagi, M. Toda and F. Toda, J. Am. Chem. Soc., 1989, 111, 697; M. Sakamoto, M. Takahashi, T. Fujita, S. Watanabe, I. Iida, T. Nishio and N. H. Aoyama, J. Org. Chem., 1993, 58, 3476.
12. See for example, T. Suzuki, T. Fukushima, Y. Yamashita and T. Miyashi, J. Am. Chem. Soc., 1994, 116, 2793; A. Sekine, K. Hori, Y. Ohashi, M. Yagi, M. Toda and F. Toda, J. Am. Chem. Soc., 1989, 111, 697; M. Sakamoto, M. Takahashi, T. Fujita, S. Watanabe, I. Iida, T. Nishio and N. H. Aoyama, J. Org. Chem., 1993, 58, 3476.
13. See for example, T. Suzuki, T. Fukushima, Y. Yamashita and T. Miyashi, J. Am. Chem. Soc., 1994, 116, 2793; A. Sekine, K. Hori, Y. Ohashi, M. Yagi, M. Toda and F. Toda, J. Am. Chem. Soc., 1989, 111, 697; M. Sakamoto, M. Takahashi, T. Fujita, S. Watanabe, I. Iida, T. Nishio and N. H. Aoyama, J. Org. Chem., 1993, 58, 3476.
14. I. D. Cunningham, B. G. Cox and N. C. Wan, J. Chem. Soc., Perkin Trans. 2, 1994, 1849.
15. I. D. Cunningham, B. G. Cox and N. C. Wan, J. Chem. Soc., Perkin Trans. 2, 1999, 693.
16. The remaining 'yield' was made up of a monomethylated product, a dimethylated product, recovered starting material and a cyanamide product (See ref. 10).
17. 2. CCDC 182/1491.
18. See E. L. Eliel and S. H. Wilen, Stereochemistry of Organic Compounds, Wiley, New York, 1994, ch. 14, p. 1120 for rules for specifying configuration due to axial chirality.
19. The less substituted and more planar N-cyano-N-(4-methoxyphenyl)guanidine has bond lengths of 1.328, 1.317 and 1.342 Å for the analogous bonds (see I. D. Cunningham, N. C. Wan, D. C. Povey, G. W. Smith and B. G. Cox, Acta Crystallogr., 1997, C53, 984). See also 'mean geometry' for guanidines from CCDC data, T. Krigowski and K. Wozniak, in Chemistry of Amidines and Imidates, Vol. 2, ed. S. Patai and Z. Rappoport, Wiley, Chichester, 1991, p 116.
20. The less substituted and more planar N-cyano-N-(4-methoxyphenyl)guanidine has bond lengths of 1.328, 1.317 and 1.342 Å for the analogous bonds (see I. D. Cunningham, N. C. Wan, D. C. Povey, G. W. Smith and B. G. Cox, Acta Crystallogr., 1997, C53, 984). See also 'mean geometry' for guanidines from CCDC data, T. Krigowski and K. Wozniak, in Chemistry of Amidines and Imidates, Vol. 2, ed. S. Patai and Z. Rappoport, Wiley, Chichester, 1991, p 116.
21. H. D. Flack, Acta Crystallogr., 1983, A39, 876; G. Bernardinelli and H. D. Flack, Acta Crystallogr., 1985, A41, 500.
22. H. D. Flack, Acta Crystallogr., 1983, A39, 876; G. Bernardinelli and H. D. Flack, Acta Crystallogr., 1985, A41, 500.
23. It is quite possible that the original sample had already undergone total spontaneous resolution, but with a material which is conformationally labile in solution and which consists of a large number of microcrystals proving this is almost impossible.
24. -1, C. L. Perrin, in Chemistry of Amidines and Imidates, Vol. 2, ed. S. Patai and Z. Rappoport, Wiley, Chichester, 1991, p. 201; Y. Yamamoto and S. Kojima, in Chemistry of Amidines and Imidates, Vol. 2, ed. S. Patai and Z. Rappoport, Wiley, Chichester, 1991, p. 509.
25. -1, C. L. Perrin, in Chemistry of Amidines and Imidates, Vol. 2, ed. S. Patai and Z. Rappoport, Wiley, Chichester, 1991, p. 201; Y. Yamamoto and S. Kojima, in Chemistry of Amidines and Imidates, Vol. 2, ed. S. Patai and Z. Rappoport, Wiley, Chichester, 1991, p. 509.
26. A concerted rotation has been observed for a tertiary aromatic amide where, as here, planarity is lost due to 'steric crowding', J. Clayden and J. H. Pink, Angew. Chem., Int. Ed., 1998, 37, 1937.