Dipolar Cycloaddition Reactions of (Phenylsulfonyl)alkanes and (Phenylsulfonyl)propadiene with C,N-Diphenylnitrone

Article abstract of DOI:10.1021/jo00384a007

The reaction of the title nitrone with (phenylsulfonyl)alkynes 1a,b results in 3-acylindoles 6a,b via unstable 4-isoxazoline cycloadducts which evolve by fission of the N-O bond and subsequent reclosure onto the ortho position of the N-phenyl substituent.Under the same conditions, the title nitrone reacts with (phenylsulfonyl)propadiene (10) to give the isomeric benzazepinone 12 and pyrrolidone 11, both of which are presumably formed from a common, transient cycloadduct.Compound 12 changes readily through a novel pathway leading to the indole derivative 14.