Cyclization of N-alkyldithiocarbamates in alkaline media, a counter example of well-known chemistry – an experimental and theoretical study

Abstract

In strong alkaline media, the reaction of 2-(tert-butylamino)ethanol (3: R = But) with CS2 at 0°C produced a cyclic dithiocarbamate, 3-tert-butylthiazolidine-2-thione (1: R = But), rather than alkaline metal or ammonium salts of [S2CN(But)CH2CH2OH]−. This is in contrast to isolation of stable alkaline metal or ammonium salts of [S2CN(R)CH2CH2OH]− (R = Me, Et, Pr, or CH2CH2OH) obtained in analogous reactions. The use of Ni(OAc)2, both as a source of Ni(II) and a weaker base, in a one-pot reaction with (3: R = But) and CS2, successfully gave the first reported metal complex of [S2CN(But)CH2CH2OH]−, namely [Ni{S2CN(But)CH2CH2OH}2] (2: R = But). Compounds 1 and 2 have been fully characterized by infrared and NMR spectroscopies, and by X-ray crystallography. DFT calculations on the cyclization and stabilities of [S2CN(R)CH2CH2OH]− (R = Pr and But) have been carried out.