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A general synthesis of allenic sulfones from acetylenes using selenosulfonation

โœ Scribed by Thomas G Back; M.Vijaya Krishna; K.Raman Muralidharan

Book ID
104227163
Publisher
Elsevier Science
Year
1987
Tongue
French
Weight
235 KB
Volume
28
Category
Article
ISSN
0040-4039

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โœฆ Synopsis

Terminal acetylenes were converted to l-and 3-substituted allenic sulfones via selenosulfonation, deprotonation, alkylation and selenoxide elimination. The free-radical selenosulfonation of acetylenes' provides R-(phenylselenolvinyl sulfones 1 in a regio-and stereoselective manner. These compounds in turn serve as precursors of a host of useful products1'2, including acetylenic sulfones 2, by selenoxide elimination (equation 1). It is interesting to note that the competing formation of allenic sulfones 2 is generally not observed when 1 contains a vinylic hydrogen atom lb (i.e. i is derived from a terminal acetylene). Since allenic sulfones are of growing synthetic importance, especially as dien+ philes3 and dipolarophiles4 in cycloaddition reactions, we endeavoured to find an alternative protocol to that shown in equation 1, which would permit their selective formation instead of the observed acetylenic sulfones. l q. 1 ox.

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