REARRANGEMENT OF ALPHA,DELTA-DICHLOROALDIMINES TO 2-FORMYLPYRROLIDINES - ALPHA,ALPHA-AZACYCLOBISALKYLATION OF ALDEHYDES

Treatment of alpha, delta-dichloroaldimines, prepared via alpha-chlori nation with N-chlorosuccinimide of the corresponding delta-chloroaldim ines, with potassium carbonate in methanol led to the formation of 1-a lkyl-2-(dimethoxymethyl)pyrrolidines in good yields. The reaction mech anism involved a skeletal rearrangement of the alpha,delta-dichloroald imines to give bicyclic aziridinium intermediates which suffered ring opening to form 1-alkyl-2-(dimethoxymethyl)pyrrolidines. The latter we re hydrolyzed in acid medium to give novel 1-alkyl-2-formylpyrrolidine s. The overall pathway involves on alpha,alpha-azacyclobis-alkylation of aldehydes.