Cyclization of N,N -Dialkyldithiocarbamate and Alkylxanthate Derivatives of Polyhalogenated Pyridines in Gas and Liquid Phases

Abstract

The intramolecular cyclization of 31 polyhalogen-substituted pyridines containing N,N-dialkyldithiocarbamate or alkylxanthate groups has been compared as a reaction in solution with sodium N,N-dialkyldithiocarbamates or potassium carbethoxydithiolate and as a gas-phase reaction under electron ionization (EI) conditions. A scheme of fragmentation for the studied compounds has been proposed. The influence of the nature of leaving groups (Cl, F, CF₃, CN, COOEt), of the presence of electron-withdrawing groups (Cl, F, CN, CCl₃, CF₃, COOEt) that are ortho, meta or para to the leaving halogen, of the position of a dithio group with respect to the pyridine nitrogen atom and of the role of oxygen and nitrogen in the corresponding alkylxanthates and N,N-dialkyldithiocarbamates on the cyclization process has been investigated.