• 10.1021/ol990794q
  • Organic Letters
  • Volume 1
  • October 1999
  • pp 1017-1019

Hydrostannation of Terminal Acetylenes

Details


The hydrostannation of alkynes is frequently used for the synthesis of vinyl stannanes, which can be subjected to further modifications via a Stille coupling. The major drawbacks of this process result from the difficulties which arise in the control of the regioselectivity of the tin-hydride addition in the case of unsymmetrical alkynes which can give rise to two products. Efforts aimed at higher α-selectivities include, Al or Mo-catalyzed hydrostannation. In search for a method to functionalize a terminal acetylenic moiety, to obtain α-stannylated compounds, the molybdenum process developed by Kazmaier et al. was chosen on the basis of its reportedly higher α-selectivities in secondary terminal propargylic systems. Application of this catalytic system on terminal acetylene as a part of a tetracyclic system resulted in very poor regioselectivity (α tin : β tin; 3:2). I believe that the isonitrile ligand was just not bulky enough to impart any regioselectivity in a complex system such as mine.



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