An acid-catalyzed ring-switch reaction of lactams to lactones: concise synthesis of 2,4-dialkyl-3-hydroxybutanolides

A novel approach for the synthesis of 2,4-dialkyl-3-hydroxybutanolides, having three successive stereogenic centers, by an acid-catalyzed ring-switch reaction of 2-(2-hydroxyalkyl)lactams is described. This transformation was applied to the synthesis of the key intermediates of teromerase inhibitor UCS1025A.