Cycloaddition reactions of 2,4-diphenyl-3-methyl-1,3-oxazolium 5-oxide with 4-methylene-4,5-dihydroisoxazoles: 1H and 13C nuclear magnetic resonance stereochemical assignments of the products

Abstract

Some 3-aryl-4-methylene-5-morpholino-4,5-dihydroisoxazoles (2) were treated with 2,4-diphenyl-3-methyl-1,3-oxazolium 5-oxide (1) to give corresponding cycloaddition products, namely spiro[isoxazolo-4,3′-pyrroles](3) and (4). The steric configuration of the spiro-derivatives has been assigned on the basis of ¹H and ¹³C n.m.r. evidence.