SYNTHETIC REACTIONS OF ISOXAZOLINE-2-OXIDES .13. TICL4 PROMOTED RING EXPANSION REACTIONS OF 5-HYDROXYMETHYL-2-ISOXAZOLINE-2-OXIDE METHANESULFONATES

5-Hydroxymethyl-2-isoxazoline-2-oxide methanesulfonates(1) possessing a substituted phenyl ring were treated with TiCl4 to afford either benzofuro[3,2-d]-1,2-oxazines(3) or 4-o-chlorophenyl-5,6-dihydro-4H-1,2-oxazines(4), depending on the nature of the substituents on the phenyl ring of 1. The reaction mechanism of the formation of 3 and 4 is proposed, including 3H-indole-1-oxide zwitterion(B) as a key intermediate.