O -Thien-2-yl Esters: A Synthetic Approach to a Rare Class of Materials Using a Modified Steglich Esterification

Herein, we describe a simple procedure for the transformation of 3-thien-2-one to O-thien-2-yl esters via modified Steglich esterification. Attempted esterification using standard Steglich conditions gave low yields due to a competing O-N acyl migration, resulting in the formation of N-acylurea as the major product. The addition of a catalytic amount of p-TSA·H₂O eliminates the formation of the N-acylurea. Various O-thien-2-yl esters have been synthesized using this procedure in yields of 51-85%.