Concave Reagents, 21. Selective Acylations of Primary and Secondary Alcohols by Ketenes

Concave pyridines 1 were used to catalyze the addition of primary and secondary alcohols to ketenes 4 , and the kinetic data of these catalyses were determined. In inter‐ and intramolecular competitions the use of 1e–g led to improved selectivities for the acylation of primary alcohols in comparison with secondary alcohols. All primary alcohols react at comparable rates. Observed rate constants were correlated with Taft's E s values. The starting materials and products were fully characterized.