Diborative Reduction of Alkynes to 1,2-Diboryl-1,2-Dimetalloalkanes: Its Application for the Synthesis of Diverse 1,2-Bis(boronate)s

Reduction of alkynes with alkali
metals in the presence of B2pin2 results in
diboration of alkynes. Distinct
from conventional dissolving metal hydrogenations, two carbon–boron
bonds and also two carbon–alkali metal bonds can be constructed
in one operation to form 1,2-diboryl-1,2-dimetalloalkanes. The 1,2-diboryl-1,2-dimetalloalkanes
generated are readily convertible to a wide range of vicinal bis­(boronate)­s.
In particular, oxidation of the 1,2-dianionic species provides (E)-1,2-diborylalkenes, unique anti-selective
diboration of alkynes being thus executed.