Studies in the dithiocarbamate series. Part II. The reaction of substituted N-benzylpiperidines with carbon disulphide

Abstract

A series of substituted N-benzylpiperidines has been prepared, and their reaction with carbon disulphide studied. When the benzyl group possesses a 4-hydroxy-substituent together with 3.5-substituents such as alkyl and methoxythe reaction leads to dithiocarbamate formation by ' insertion ' of carbon disulphide between the benzylic carbon atom and nitrogen. A three-stage mechanism is proposed, one stage involving the formation of ap-quinone methide as a transient intermediate. An alternative two-stage mechanism is considered but shown to be less likely.WHEREAS the reaction between carbon disulphide and primary or secondary amines is well-known, that between carbon disulphide and tertiary amines has been less studied. With certain tertiary amines, dithiocarbamate formation occurs by ' insertion ' of carbon disulphide into a carbon-nitrogen bond of the amine. Thus, the Mannich base N-(4-hydroxy-3,5-di-t-butyl-benzy1)piperidine (Ia) was recently shown to yield-4-hydro~y-3~5-di-t-butylbenzyl piperidine-l-carbodithioate (IIa) on treatment with carbon disulphide, and