- The Cyclic Dipeptide cyclo as a Catalyst for Asymmetric Addition of Hydrogen Cyanide to Aldehydes
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cyclo (cyclo, 1) catalyzes the addition of hydrogen cyanide to benzaldehyde in toluene at -20 deg C to afford (R)-mandelonitrile with enantiomeric excess of 97 percent in high yield. cyclo gives (S)-mandelonitrile. cyclo (1) exhibits a broad substrate specificity, and a variety of aldehydes (3a-r) such as m-methoxybenzaldehyde (3c), 6-methoxy-2-naphthaldehyde (3k), and isobutyraldehyde (3o) similarly afforded the corresponding cyanohydrins with high enantiopurities (97 percent ee for 3c, 93 percent ee for 3k, 71 percent ee for 3o). (R)-Mandelonitrile thus obtained was successfully converted to various chiral synthons such as mandelic acid (7), methyl mandelate (8), and 2-amino-1-phenylethanol (9) without any racemization.
- Tanaka, Kenzo,Mori, Atsunori,Inoue, Shohei
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p. 181 - 185
(2007/10/02)
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