The Suzuki-Miyaura cross-coupling of aryl phosphates using Ni(PCy(3))(2)Cl(2) as an inexpensive, bench-stable catalyst is described. Broad substrate scope and high efficiency are demonstrated by the syntheses of more than 40 biaryls and by constructing complex organic molecules. The poor reactivity of aryl phosphates relative to aryl halides is successfully employed to construct polyarenes by selective cross-coupling using Pd and Ni catalysts.
As a cheap and easily obtainable
raw material, epichlorohydrin
is an attractive candidate for copolymerization with CO2 to produce degradable polycarbonate. However, the poor polymer selectivity
as well as the concomitant production of ether linkage units in the
previous studies hindered further research on this topic, such as
asymmetric, stereo- and regioselective ring-opening of epichlorohydrin
during its copolymerizaton with CO2. Herein, we report
highly stereospecific alternating copolymerization of CO2 and epichlorohydrin for the first time by utilizing chiral bifunctional
cobalt–salen catalysts. It was found that the substituents
on the phenonate groups around the metal center had a notable effect
on the regioselectivity of the ring-opening step for epichlorohydrin.
Using an enantiopure salenCo(III) complex bearing an adamantane group
and an appended bulky dicyclohexyl ionic ammonium salt, a highly regioregular
ring-opening step was observed with a concomitant 97% retention of
configuration at the methine carbon center. The isotactic poly(chloropropylene
carbonate) is a typical semicrystalline polymer with an enhanced T
g of 42 °C and a T
m of 108 °C. The test of mechanical properties shows that
the yield strength and tensile strength of the crystalline copolymer
are about 10 and 30 times that of its amorphous counterpart, respectively.
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.