Looking beyond Benzoin: Thiamine-Mediated Efficient Aroylation of Cyclic Vinamidinium Salt with Aldehydes

Herein, we report a thiamine-promoted new aroylation strategy employing cyclic vinamidinium salt with aromatic aldehydes leading to 4-aroyl 1,3-dimethylpyrimidine-2(<i>1H</i>)-one scaffold. This protocol explores thiamine hydrochloride as an umpolung reagent and delivers 23 biologically relevant compounds with yields ranging between 60 and 80%. The gram-scale synthesis and further functionalization of products highlight the efficiency and usefulness of the developed method in creating scores of dihydropyrimidinone derivatives.