Rhodium-Catalyzed Enantioselective 1,6-Addition of Arylboronic Acids to Enynamides: Asymmetric Synthesis of Axially Chiral Allenylsilanes
摘要:
Rhodium-catalyzed asymmetric 1,6-addition of arylboronic acids to beta-alkynyl acrylamides substituted with a silyl group on the alkyne terminus took place to give high yields of axially chiral allenylsilanes with 94-99% enantioselectivity, which was realized by use of a rhodium/chiral diene complex.
Highly Stereoselective Synthesis of α-Alkyl-α-Hydroxycarboxylic Acid Derivatives Catalyzed by a Dinuclear Zinc Complex
作者:Barry M. Trost、Keiichi Hirano
DOI:10.1002/anie.201201116
日期:2012.6.25
dinuclear zinc–ProPhenol catalyst enables highly enantioselective nitro‐Michael reactions with oxazol‐4(5H)‐ones as nucleophilic substrates (see scheme, Nap=2‐naphthyl). This work highlights the utility of the ProPhenol family of ligands. The modular nature of these ligands proved crucial in the optimization of reaction conditions to achieve excellent stereoselectivities.
Oxidative alkynylation of acrylate esters with propargylic alcohols giving conjugated enyne esters was realized by use of a diene–rhodium catalyst. Propargylic alcohols were found to be useful alkynylating reagents in the present reaction to produce alkynylrhodium species via carbon–carbon bond cleavage. An excess of the acrylate ester worked as a hydride acceptor to reproduce the active rhodium species
Rhodium-catalyzed asymmetric 1,6-addition of arylboronic acids to beta-alkynyl acrylamides substituted with a silyl group on the alkyne terminus took place to give high yields of axially chiral allenylsilanes with 94-99% enantioselectivity, which was realized by use of a rhodium/chiral diene complex.