InCl₃-Mediated Cleavage of Acetonides on Acid-Sensitive Heterocycles

Significance

Reported is the indium trichloride mediated acetonide cleavage of acid-sensitive 1,3-dioxolanyl-1,2-oxazine derivatives 1. The use of this weak Lewis acid was necessary due to the instability of the parent 1,2-oxazine. Attempted acetonide cleavage with stronger Lewis acids gave 1,2-oxazinones 3 (H.-U. Reissig, A. Al-­Harrasi Angew. Chem. Int. Ed. 2005, 44, 6227) and with Brønsted acids gave bicyclic tetrahydrofurans 4 (H.-U. Reissig and co-workers Eur. J. Org. Chem. 2008, 467). Screening of alternative weak Lewis acids established the superiority of ­Indium trichloride for these reactions.