Microwave irradiation accelerates some difficult Wittig reactions of stable phosphorus ylides (e.g. 1) with ketones. Irradiation in a domestic microwave oven of the mixture of reactants, in absence of solvents, allowed to obtain, in shorter times, an improvement of transformation yields over conventional heating method.
Optimization of asymmetric hydrogenation of 3-phenyl-3-butenoic acid catalyzed by rhodium(I)-4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyldioxolane (DIOP)
作者:Keiji Yamamoto、Kiyoshi Ikeda、Leong Kwai Yin
DOI:10.1016/0022-328x(89)87295-x
日期:1989.7
homogeneous hydrogenation of 3-phenyl-3-butenoic acid (1) has extensively been examined in the presence of the rhodium(I)/4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyldioxolane (DIOP) catalyst systems. Optimization of the reaction conditions was undertaken mainly by controlling effects of added tertiary amines as well as solvent polarities on the enantio-selectivity of the product. The best asymmetric yield
A novel ketone olefination via organozinc reagents in the presence of diphenyl phosphite
作者:Hua Cui、Ying Li、Songlin Zhang
DOI:10.1039/c2ob06821d
日期:——
Carbonyl compounds react with organozinc reagents in the presence of diphenyl phosphite to give the corresponding olefins. A variety of 1,3-dienes and unsaturated esters were obtained in moderate to excellent yields under mild conditions.
A New Cobalt–Salen Catalyst for Asymmetric Cyclopropanation. Synthesis of the Serotonin–Norepinephrine Repuptake Inhibitor (+)-Synosutine
作者:James D. White、Subrata Shaw
DOI:10.1021/ol501549x
日期:2014.8.1
A new C2 symmetric cobalt(II)–salen catalyst based on cis-2,5-diaminobicyclo[2.2.2]octane as the chiral scaffold was prepared which, in the presence of potassium thioacetate as the promoter, catalyzed the formation of cyclopropanes from 1,1-disubstituted ethylenes and ethyl diazoacetate in high yield and with excellent diastereo- and enantioselectivity. Asymmetriccyclopropanation with the catalyst
Tandem Blaise/retro-Blaise Reaction for the Nitrile-Mediated Regioselective Intermolecular Addition of Unstabilized Zinc Ester Enolates (Reformatsky Reagents) to 1-Alkynes and 1,3-Enynes
作者:Ju Hyun Kim、Yu Sung Chun、Sang-gi Lee
DOI:10.1021/jo402015n
日期:2013.11.15
of a nitrile as a mediator to achieve the regioselective intermolecular addition of unstabilized zinc ester enolates (Reformatskyreagents) to 1-alkynes and 1,3-enynes. This reaction is made possible by a reversible addition of enolates to a nitrile (Blaise reaction), generating a zinc aza-enolate that, unlike zinc ester enolates, can add intermolecularly to 1-alkynes and 1,3-enynes. Subsequent removal