The chemistry of benzotriazole. A novel and versatile synthesis of 1-alkyl-, 1-aryl-, 1-(alkylamino)-, or 1-amido-substituted and of 1,2,6-trisubstituted piperidines from glutaraldehyde and primary amines or monosubstituted hydrazines

Abstract

Various primary amines and 1-mono- and 1,1-disubstituted hydrazines were converted into the corresponding N-substituted piperidines in good to excellent yields via the products of double condensations with benzotriazole and glutaraldehyde. Reduction of the 2,6-bis(benzotriazolyl) N-substituted piperidines 4 and 7 with sodium borohydride in tetrahydrofuran afforded N-substituted piperidines. The benzotriazole moieties were also replaced by alkyl groups by reaction with Grignard reagents to produce 1,2,6-trisubstituted piperidines