One-step Direct Conversion of Heterocyclic Aldehydes to Esters

One-step direct conversion of a series of heterocyclic aldehydes to heterocyclic esters is reported here by the use of thiamine hydrochloride as a catalyst in the absence of nitrogen atmosphere in a reasonably high yield. This method exclusively produces heterocyclic esters in most cases (specially with more electron-withdrawing heterocyclic aldehydes) without the formation of side products like heteroin. Thus the method developed looks promising and general for the synthesis of electron-withdrawing heterocyclic esters from the corresponding aldehydes.