ChemInform Abstract: Two Rearrangement Pathways in the Geminal Acylation of 2‐Methoxyoxazolidines Leading to Substituted 1,4‐Oxazines.

Abstract

Substituted 1,4-Oxazines. -Lewis acid-mediated geminal acylation of 2-methoxyoxazolidines with five-or six-membered acyloins followed by heterocyclization affords 1,4-oxazines fused to cyclopentenone or cyclohexenone rings. The position of the carbonyl group in the products depends on whether or not water is present during the ring-expanding acyl migration step. The route lacking water during the acyl migration step is best conducted in one pot. The addition of water effects cleavage of a silyloxy group in the intermediate during the initial Mukaiyama aldol reaction prior to the acyl migration. -(MOULINS, J. R.; HUGHES, J. A.; DOYLE, L. E.; CAMERON, T. S.; BURNELL*, D. J.; Eur. J. Org. Chem. 2015, 6, 1325-1332, http://dx.doi.org/10.1002/ejoc.201403371 ; Dep. Chem., Dalhousie Univ., Halifax, Nova Scotia B3H 4R2, Can.; Eng.) -Nuesgen 27-226