Regioselective Synthesis of New 5-Ethoxycarbonylmethyl-4-oxothiazolidin-2-ylidene Bromides and Rearrangement Reaction Thereof

Abstract

Z)-5-Substituted-2-alkylidene-4-oxothiazolidine derivatives 2a-c were regioselectively brominated to afford the new, synthetically useful vinyl bromides 3a-c. They undergo novel rearrangement reaction to provide 4-oxothiazolidine derivatives 5a-c containing two fully conjugated exocyclic double bonds. Extremely clean and efficient derivatization of 2a-c to 5a-c was also achieved by a one-pot three-step sequence under mild experimental conditions without isolation of vinyl bromides 3a-c.

Chemistry of Ketene N,S-Acetals: An Overview

“…Similarly to cyclic ketene S , S -acetals, , 229a – c can be brominated under mild reaction conditions to afford the desired bromo ketene N , S -acetals, which adopt either the Z configuration for 234a / c or the E configuration for 234b , consistent with 1 H NMR data for the amino hydrogen (Scheme ). − Bromo ketene N , S -acetals can be further converted under different conditions, for example, through pyridine-assisted bromine transfer , or functionalization based on DMSO-assisted carbon–bromine bond cleavage …”