Highly Diastereoselective Esterification of Ketenes Generated In Situ from Acyl Chlorides with (R)‐Pantolactone Derivatives

Our mechanistic investigations have revealed that Et3N is a key requirement for the highly diastereoselective formation of esters from the corresponding acyl chlorides with (R)-pantolactone via ketene-derived complexes. Furthermore, we have discovered that (R)-N-benzyl-pantolactam is a more effective chiral alcohol than (R)-pantolactone for the esterification of in situ generated ketenes.