title: Enantiospecific Alkynylation of Alkylboronic Esters.
abstract: Enantioenriched secondary and tertiary alkyl pinacolboronic esters undergo enantiospecific deborylative alkynylation through a Zweifel-type alkenylation followed by a 1,2-elimination reaction. The process involves use of α-lithio vinyl bromide or vinyl carbamate species, for which application to Zweifel-type reactions has not previously been explored. The resulting functionalized 1,1-disubstituted alkenes undergo facile base-mediated elimination to generate terminal alkyne products in high yield and excellent levels of enantiospecificity over a wide range of pinacolboronic ester substrates. Furthermore, along with terminal alkynes, internal and silyl-protected alkynes can be formed by simply introducing a suitable carbon- or silicon-based electrophile after the base-mediated 1,2-elimination reaction.
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
authors.forename: Yahui
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Noble
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
authors.forename: Eddie L
authors.initials: EL
authors.lastname: Myers
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK. v.aggarwal@bristol.ac.uk.
authors.forename: Varinder K
authors.identifier: http://orcid.org/0000-0003-0344-6430
authors.initials: VK
authors.lastname: Aggarwal
keywords: alkynes; alkynylation; boronic esters; synthetic methods