Highly selective synthesis of (E)-3-methyl-1-trialkylsilyl-3-en-1-ynes via trans-selective alkynylation catalyzed by Cl2Pd(DPEphos) and stereospecific methylation with methylzincs catalyzed by Pd(tBu3P)2

Organic Letters
Ji-Cheng ShiEi-ichi Negishi

Abstract

[reaction: see text] trans-Selective (>or=98%) monoalkynylation of 1,1-dibromo-1-alkenes and 1,1-dichloro-1-alkenes catalyzed by Cl(2)Pd(DPEphos) followed by stereospecific methylation with Me(2)Zn or MeZnX (X= Cl or Br) catalyzed by Pd((t)()Bu(3)P)(2) provides an efficient and stereoselective (>or=98%) route to 5, convertible to a wide variety of enynes and conjugated dienes. In the cases of 1,1-dibromo-1-alkenes, the Sonogashira alkynylation may also be satisfactory, but it is distinctly less satisfactory than the alkynylzinc reaction in cases where 1,1-dichloro-1-alkenes are used.

Citations

Nov 17, 2011·Chemical Reviews·Giorgio Chelucci
Apr 10, 2007·Journal of the American Chemical Society·Feng RenAndrew G Myers
Jan 4, 2006·The Journal of Organic Chemistry·Daniela Andrei, Stanislaw F Wnuk
Feb 12, 2005·Organic Letters·Mikkel F JacobsenJack E Baldwin
Jul 7, 2005·Organic & Biomolecular Chemistry·Ruben P van SummerenAdriaan J Minnaard
Feb 27, 2021·Beilstein Journal of Organic Chemistry·Beatrice LansbergenMichael C McLeod
Dec 23, 2008·The Journal of Organic Chemistry·Jeongju MoonSunwoo Lee
Feb 20, 2007·Chemical Reviews·Rafael Chinchilla, Carmen Najera
Mar 27, 2009·The Journal of Organic Chemistry·David I Chai, Mark Lautens
Mar 31, 2021·Chemistry : a European Journal·Patrick ZimdarsPeter Metz
Mar 15, 2015·Journal of the American Chemical Society·Daniel HerkommerDirk Menche
Nov 6, 2003·Journal of the American Chemical Society·Xingzhong ZengEi-ichi Negishi
Jun 4, 2005·Organic Letters·Mikkel F JacobsenJack E Baldwin

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