摘要:
L-Proline derived diastereoisomeric [4.4]-spirolactams have been prepared by a reductive-amination reaction of (R)- or (S)-alanine methyl ester, followed by thermal cyclisation of the resulting amine onto the proline ester group in refluxing toluene. Under similar conditions (R)- or (S)-phenylalanine methyl ester gave no cyclisation products, while R- or S-alpha-methylbenzylamine required treatment with NaNH2 in refluxing toluene to induce cyclisation giving diastereoisomeric [4.4]-spirolactams. (c) 2006 Elsevier Ltd. All rights reserved.