<i>O</i> -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 <i>O</i>-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 <i>N</i>-acylurea as the major product. The addition of a catalytic amount of <i>p</i>-TSA·H₂O eliminates the formation of the <i>N</i>-acylurea. Various <i>O</i>-thien-2-yl esters have been synthesized using this procedure in yields of 51-85%.