2-Trialkylphosphonio-1,3-dithiole-4-carboxylates. Reaction of acetylene carboxylic acids with trialkylphosphine–carbon disulphide zwitterions

Acetylene carboxylic acids were treated with trialkylphosphine–carbon disulphide zwitterions to produce fair to good yields of 2-trialkylphosphonio-1,3-dithiole-4-carboxylates; the zwiterionic structure of the products was established by i.r. and n.m.r. spectroscopy and from the structure of their hydrolysis products.