Ring-Opening Diarylation of Siloxydifluorocyclopropanes by Ag(I) Catalysis: Stereoselective Construction of 2-Fluoroallylic Scaffold
作者:Xiaoning Song、Cong Xu、Dongxu Du、Ziming Zhao、Dongsheng Zhu、Mang Wang
DOI:10.1021/acs.orglett.7b03254
日期:2017.12.15
A silver-catalyzed, defluorination ring-opening diarylation of siloxy 2,2-difluorocyclopropanes, with two arenes, to directly prepare polysubstituted 2-fluoroallylic compounds, is described. This multicomponent reaction proceeds smoothly in good stereoselectivity, which is due to a chelation-controlled addition of arenes to α-fluorinated ketone intermediate.
Catalytic, Enantioselective Alkylation of α-Imino Esters: The Synthesis of Nonnatural α-Amino Acid Derivatives
作者:Dana Ferraris、Brandon Young、Christopher Cox、Travis Dudding、William J. Drury、Lev Ryzhkov、Andrew E. Taggi、Thomas Lectka
DOI:10.1021/ja016838j
日期:2002.1.1
Methodology for the practical synthesis of nonnatural amino acids has been developed through the catalytic, asymmetric alkylation of α-imino esters and N,O-acetals by enol silanes, ketene acetals, alkenes, and allylsilanes using chiral transition metal-phosphine complexes as catalysts (1−5 mol %). The alkylation products, which are prepared with high enantioselectivity (up to 99% ee) and diastereoselectivity
[reaction: see text] Catalytic, enantioselective Mannich-type reactions of alpha-imino estersbearing readily removable substituents on nitrogen are described. Several N-carbamate-protected alpha-imino esters, which are readily prepared from 2-bromoglycine esters using a polymer-supported amine, reacted with silicon enolates to afford the desired adducts in high yields with high enantioselectivity
Various β-nitro ketones, including those bearing a β-tertiary carbon, were prepared from geminal bromonitroalkanes and trimethylsilyl enol ethers of a broad range of ketones by visiblelightphotoredoxcatalysis, which were then easily converted into β-amino ketones, 1,3-amino alcohols, α,β-unsaturated ketones, β-cyano ketones and γ-nitro ketones.
α-Arylation of Silyl Enol Ethers via Rhodium(III)-Catalyzed C–H Functionalization
作者:Xuezhen Kou、Kevin G. M. Kou
DOI:10.1021/acscatal.9b05622
日期:2020.3.6
Carbon–hydrogen (C–H) bond functionalization streamlines synthesis by increasing step- and atom-economies. This approach, catalyzed by Rh(III), is combined with the α-arylation of ketone-derived silyl enol ethers to achieve a direct cross-coupling event. The advancement of electron-rich alkenes as substrates is enabled through the use of a silver additive and complements existing C–H activation methods