Improved Methodology for the Preparation of Chiral Amines

3.5. Conclusion:
Different methodologies have been introduced for the synthesis of α- chiral amines. One of
the most important strategy introduced for this purpose is reductive amination. Reductive
amination is a stepwise efficient methodology starting from the prochiral ketone to the α-
chiral amine. Earlier reports described the use of classical heterogeneous catalysts for this
transformation. Homogeneous catalysts were also introduced in the seventies and marked a
significant breakthrough in the field. Asymmetric version was introduced utilizing chiral
catalyst, chiral auxiliaries or chiral organocatalysts. The use of Brønsted or Lewis acids was
important in most of the methodologies. Earlier reports suggested the role of the acid as an
efficient desiccant but recent reports suggested more complicated function as forcing
hemiaminal formation. Over the last two decades several methodologies were evolved
allowing the synthesis of α- chiral amines from aryl-alkyl ketone and 2-alaknones in good to
high yields and enantioselectivities. [68]
3.6. References:
[1] 1. Mignonac, G. Compt. Rend. 1921, 172, 223.
[2] For review articles, see (a) W. S. Emerson, Org. React. 1948, 4, 174; (b) F. Möller, R.
Schröter, in Methoden der Organischen Chemie (Houben-Weyl), Thieme: Stuttgart; Bd. XI/1,
1957, 602–673.
[3] S. Nishimura, Handbook of Heterogeneous Catalytic Hydrogenation for Organic
Synthesis, John Wiley &Sons, Inc., New York, 2001.
[4] C. F. Winans, J. Am. Chem. Soc. 1939, 61, 3566.
[5] B. M. Vanderbilt, U.S. Pat. 2,219,879, 1941.
[6] E. H. Pryde, D. E. Anders, J. C. Cowan, J. Am. Oil Chem. Soc. 1969, 46, 67.
[7] A. Skita, F. Keil, Ber. Dtsch. Chem. Ges. 1928, 61, 1682.
[8] R. Cantarel, Compt. Rend. 1940, 210, 403.
[9] Winans, C. F.; Adkins, H. J. Am. Chem. Soc. 1932, 54, 306
[10] A. C. Cope, E. M. Hancock, J. Am. Chem. Soc. 1942, 64, 1503
[11] Dovell, F. S.; Greenfield, H. J. Org. Chem. 1964, 29, 1265
[12] F. S. Dovell, H. Greenfield, J. Am. Chem. Soc. 1965, 87, 2767
[13] L. Marko, J. Bakos, J. Organomet. Chem. 1974, 81, 411
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