One-pot, three-step synthesis of cyclopropylboronic acid pinacol esters from synthetically tractable propargylic silyl ethers

Spencer, Jonathan A. and Jamieson, Craig and Talbot, Eric P. A. (2017) One-pot, three-step synthesis of cyclopropylboronic acid pinacol esters from synthetically tractable propargylic silyl ethers. Organic Letters. ISSN 1523-7060

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    Abstract

    Simple propargylic silyl ethers can be converted to complex cyclopropylboronic acid pinacol esters in an efficient onepot procedure. Terminal acetylenes undergo a Schwartz’s reagent catalyzed hydroboration; subsequent addition of further Schwartz’s reagent and Lewis acid-mediated activation of neighboring silyl ether allows cyclization to access a range of cyclopropylboronic acid pinacol esters. The scope includes aromatic, aliphatic, quaternary, and spiro substituted cyclopropyl rings, which can be transformed via Suzuki coupling into a range of lead-like substituted cyclopropyl aryl products.