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Spirobicyclic Diamines 2: Synthesis Of Homochiral Diastereoisomeric Proline Derived [4,4]-Spirolactams, Fintan Kelleher, Sinead Kelly

Articles

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-a-methylbenzylamine required treatment with NaNH₂ in refluxing toluene to induce cyclisation giving diastereoisomeric [4.4]-spirolactams