DMAP-promoted cascade C-S/C-N bonds formation approach to 1,3-thiazolidin-4-ones via annulation of β-ketothioamides with α-halocarboxylic acids at room temperature

An operationally simple and efficient one-pot straightforward method for the construction of 1,3-thiazolidin-4-ones has been developed by cyclocondensation of beta-ketothioamides and an in situ generated acid anhydride from alpha-halocarboxylic acid in the presence of DCC at room temperature. The attractive features of this strategy include metal-free mild reaction conditions, short reaction time, and efficacy of forming consecutive C-S and C-N bonds and one ring in a single synthetic operation. Noteworthy, a Z-stereochemistry was observed for the exocyclic alpha-oxoketene moiety at 2-position of 1,3-thiazolidine ring. (C) 2014 Elsevier Ltd. All rights reserved.