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Haloboration of Internal Alkynes with Boronium and Borenium Cations as a Route to Tetrasubstituted Alkenes

Authors


  • This research was supported by the Royal Society (M.J.I.), the Leverhulme Trust (E.R.C.), the EPSRC (I.A.C. and J.R.L.), and Cambridge Display Technologies (S.A.S.). We also acknowledge use of the EPSRC UK National Service for Computational Chemistry Software (NSCCS) for this research.

Abstract

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Hail boration! 2-Dimethylaminopyridine-ligated dihaloborocations [X2B(2-DMAP)]+ with a strained four-membered boracycle were used for the haloboration of terminal and dialkyl internal alkynes (see scheme). Esterification then provided vinyl boronate esters as useful precursors to tetrasubstituted alkenes. Following mechanistic studies, the scope of the haloboration was expanded simply by variation of the amine. Pin=2,3-dimethyl-2,3-butanedioxy.

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