Tetrakis(methoxo)- or bis(pinacolato)diboron
[(RO)2BB(OR)2; (RO)2 =
(MeO)2 (4a) and
Me4C2O2 (1)] added to
both terminal and internal alkynes in the presence of a
catalytic
amount of Pt(PPh3)4 to provide
stereodefined cis-bis(boryl)alkenes (3)
in excellent yields.
Because reagents and reaction conditions were sufficiently mild,
the procedure was readily
extended to various functionalized alkynes. Mechanistic study
revealed that the oxidative
addition of bis(pinacolato)diboron (1) to
Pt(PPh3)4 generates
cis-Pt(BO2C2Me4)2(PPh3)2
(5),
whose structure was fully characterized by multinuclear NMR
spectroscopies as well as
single-crystal X-ray diffraction analysis. Complex 5
exhibited high reactivity for insertion
to the alkyne giving 3 in high yields, thus implying that
the oxidative addition of the B−B
bond to a Pt(0) complex is an initial step in the
platinum(0)-catalyzed diboration of alkynes.
1994organo-boron compounds, nonmetal heterocycles organo-boron compounds, nonmetal heterocycles S 0047
-202Platinum(0)-Catalyzed Diboration of Alkynes.-Although solvents do not play an important role in the title reaction yielding the products (III), the addition is apparently accelerated in polar solvents in the order DMF ¿ MeCN ¿ THF ¿ toluene. By boron cross-coupling reaction, the decene (V) is prepared. -(ISHIYAMA, T.; MATSUDA, N.; MIYAURA, N.; SUZUKI, A.;
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.