Synthesis of enantiopure (R,R)- and (S,S)-cis-2,3-propanoprolines
摘要:
A novel approach to the synthesis of an enantiopure bicyclic proline analogue, hexahydrocyclopentalb]pyrrole-6a(1H)-carboxylic acid ('2,3-propanoproline'), has been developed. The method relied on tandem Strecker-nucleophilic cyclization reaction of 2-(2-bromoethyl)cyclopentanone. The overall synthetic scheme included six steps and resulted in 18% overall yield of both enantiomers of the title amino acid. (C) 2010 Elsevier Ltd. All rights reserved.
The synthesis of a highly constrained quaternary carbocyclic alpha-amino acid, (+)-N-Boc-bicycloproline, has been achieved starting from sodium cyclopentadienylide. Key steps include a rhodium-catalyzed nitrenoid C-H insertion to install the tert-alkylamine and a ring-closing metathesis reaction to form the pyrrolidine ring. (C) 2009 Elsevier Ltd. All rights reserved.