Highly(98%) Selective Trisubstituted Alkene Synthesis of Wide Applicability via Fluoride-Promoted Pd-Catalyzed Cross-Coupling of Alkenylboranes. Academic Article uri icon

abstract

  • (Z)--bromo-1-propenyl(pinacol)borane(4), recently made available in 85% yield as a 98% isomerically pure compound via bromoboration of 1-propyne, has been converted to -alkyl-, aryl-, and alkenyl-substituted (Z)-2-methyl-1-alkenyl(pinacol)boranes(2a) in ca. 75% yield based on propyne via Pd-catalyzed Negishi alkenylation with suitable organozinc bromide. The previously sluggish and modest-yielding Suzuki alkenylation of ,-disubstituted alkenylboranes has been significantly promoted by fluorides, especially nBu4NF(TBAF) or CsF to give trisubstituted alkenes, i.e., (Z)--Me-substituted 3-i-3-xi and (E)--Ph-substituted 2b-i and 2b-ii. In all cases, each alkene product was formed in a 98% seteoselectivity. The propyne-based protocol nicely complements the widely used Zr-catalyzed alkyne methylalumination-Pd-catalyzed alkenylation by providing a highly stereoselective(98%) route to (Z)-Me-substituted alkenes.

published proceedings

  • Isr J Chem

author list (cited authors)

  • Negishi, E., Tobrman, T., Rao, H., Xu, S., & Lee, C.

citation count

  • 17

complete list of authors

  • Negishi, Ei-Ichi||Tobrman, Tomas||Rao, Honghua||Xu, Shiqing||Lee, Ching-Tien

publication date

  • January 2010

publisher