Enantioselective (3+2) cycloaddition <i>via</i> N-heterocyclic carbene-catalyzed addition of homoenolates to cyclic <i>N</i>-sulfonyl trifluoromethylated ketimines: synthesis of fused N-heterocycle γ-lactams
作者:Zhen-Zhen Zhang、Yongna Zhang、Hui-Xin Duan、Zhuo-Fei Deng、You-Qing Wang
DOI:10.1039/c9cc09269b
日期:——
An enantioselective (3+2) cycloaddition of enals and cyclic N-sulfonyl trifluoromethyl ketimines via N-heterocyclic carbene-catalyzed homoenolateaddition is described. This reaction can efficiently construct fused N-heterocycle γ-lactams bearing two adjacent chiral centers with >20 : 1 dr and 94-99% ee, with one chiral center as a trifluoromethylated α-tetrasubstituted carbon stereocenter.
Synthesis of α-Quaternary Formimides and Aldehydes through Umpolung Asymmetric Copper Catalysis with Isocyanides
作者:Kentaro Hojoh、Hirohisa Ohmiya、Masaya Sawamura
DOI:10.1021/jacs.6b12881
日期:2017.2.15
A highly regio- and enantioselective copper-catalyzed three-component coupling of isocyanides, hydrosilanes, and γ,γ-disubstituted allylic phosphates/chlorides to afford chiral α-quaternary formimides was enabled by the combined use of our original chiral naphthol-carbene ligand as a functional Cu-supporting ligand and LiOtBu as a stoichiometric Lewis base for Si. The formimides were readily converted
通过结合使用我们原始的手性萘酚-卡宾配体,实现了高度区域选择性和对映选择性铜催化的异氰化物、氢硅烷和 γ,γ-二取代的烯丙基磷酸酯/氯化物的三组分偶联,以提供手性 α-季铵甲酰亚胺。功能性 Cu 支持配体和 LiOtBu 作为 Si 的化学计量路易斯碱。甲酰亚胺很容易转化为α-季醛。
Identification of Suitable Ligands for a Transition Metal-Catalyzed Reaction: Screening of a Modular Ligand Library in the Enantioselective Hydroboration of Styrene
general modular synthetic scheme, a variety of chiral bidentate P/P-, P/S-, P/N-, and P/Se-ligands is accessible in an efficient divergent manner starting from phenol or naphthol derived backbone systems. A library of 20 selected ligands was tested in the Rh-catalyzed asymmetric hydroboration of styrene to give 1-phenylethanol in up to 91% ee after oxidative work-up. It was demonstrated that small variations
Zirconium Sulfophenyl Phosphonate Zr(O3PCH3)(1.2)(O3PC6H4SO3H)(0.8) was found to be an efficient heterogeneous catalyst for the tetrahydropyranylation of alcohols and phenols. (C) 1998 Elsevier Science Ltd. All rights reserved.