M. Ochiai, M. Kunishima, S. Tani
Apr 1, 1991
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Journal
Journal of the American Chemical Society
Abstract
Michael-type addition of benzenesulfinic acid to alkynyl(phenyl) iodonium tetrafluoroborates in methanol gives stereoselectively (Z)-(β-(phenylsulfonyl) alkenyl) iodonium tetrafluoroborates in high yields. [β-(Phenylsulfonyl) alkylidene] carbenes derived from the (Z)-(β-(phenylsulfonyl) alkenyl) iodonium tetrafluoroborates by base treatment predominantly undergo intramolecular 1,5-carbon-hydrogen insertions to give 1-(phenylsulfonyl) cyclopentenes along with a small amount of rearranged alkynes, which is in a marked contrast with the facile 1,2-migration of β-(phenylsulfenyl) and β-(phenylsulfinyl) groups of alkylidenecarbones. Reaction of alkynyl(phenyl) iodonium tetrafluoroborates with benzenesulfinates directly affords 1-(phenylsulfonyl) cyclopentenes via tandem Michael-carbene insertion reactions. The mechanism of 1,2-migration of [β-(phenylsulfonyl) alkylidene] carbenes is also discussed