Asymmetric Catalysis of the Strecker Amino Acid Synthesis by a Cyclic Dipeptide

摘要

The condensation of aldehydes with ammonia and hydrogen cyanide to form alpha-amino nitriles followed by hydrolysis of the nitrile groups (the Strecker synthesis) is the oldest known method for the de novo synthesis of a-amino acids. The ever-increasing interest in nonproteinogenic alpha-amino acids in a variety of scientific disciplines has prompted the development of numerous methods for the asymmetric synthesis of a-amino acids. Among the methods developed, several enantioselective versions of theStrecker synthesis in which optically active amines replace ammonia to serve as ehiral auxiliaries, with moderate to good levels of asymmetric induction, have been reported. To avoid the problems inherent to the use of ehiral auxiliaries (e.g., cost) one must instead use 2 ehiral catalyst. In this communication we report a version of the Strecker synthesis employing such a ehiral catalyst, permitting the conversion of aldehydes to (S)-amino acids in high yield and, in some cases, exceptionally high enantiomeric excess.