Reagent‐Controlled Chemodivergent Approach to Thiazolines and Thiazines from α‐N‐Hydroxyimino Dithioesters

Abstract

A chemoselective route to thiazolines and thiazines has been devised by heterocyclization of viable α-N-hydroxyimino-β-oxodithioesters with 2-chloroethylamine hydrochloride/3-chloropropylamine hydrochloride, which does not require metals or additives and proceeds at 0-60 °C. The overall transformation involves base mediated intramolecular cyclization of α-N-hydroxyimino-β-oxodithioesters to 4-membered oxazete-4-thione intermediates followed by coupling with chloroalkyl amines via tandem ring cleavage and CÀ N/CÀ S bonds formation enabling the construction of thiazolines/thiazines in one-pot. This strategy allows broadening the arsenal of synthetic methods to obtain N,S-heterocycles utilizing substrates prepared according to reported procedures.

A decade update on the application of β-oxodithioesters in heterocyclic synthesis

“…In 2022, an interesting study on the synthesis of thiazolines 30-3 from α- N -hydroxyimino-β-oxodithioesters 30-1 and 2-chloroethylamine hydrochloride 30-2 via sequential C–N and C–S bonds forming in the presence of DABCO was demonstrated by Singh's group (Scheme 30). 47 This metal-free process involved DABCO-promoted intramolecular cyclization of α- N -hydroxyimino-β-oxodithioesters to generate 4-membered oxazete-4-thiones 30-B followed by ring-opening with 2-chloroethylamine hydrochloride and recyclization to construct thiazoline rings in one-pot.…”