Chemo- and diastereoselective Bi(OTf)3-catalyzed benzylation of silyl nucleophiles
作者:Philipp Rubenbauer、Thorsten Bach
DOI:10.1016/j.tetlet.2007.12.092
日期:2008.2
The direct alkylation of silyl enol ethers with para-methoxybenzylic alcohols or their corresponding acetates was efficiently catalyzed by Bi(OTf)3 in CH3NO2 as the solvent. The reaction provided the α-benzylated carbonylcompounds in high yields after short reaction times using 1–2.5 mol % of the catalyst. Benzylic acetates other than para-methoxybenzylic acetates also underwent the reaction. High
Bi(OTf)3在作为溶剂的CH 3 NO 2中有效地催化了甲硅烷基烯醇醚与对甲氧基苄醇或其相应的乙酸酯的直接烷基化。使用1–2.5 mol%的催化剂,反应在较短的反应时间后即可以高收率得到α-苄基羰基化合物。除对甲氧基苄基乙酸酯以外的乙酸苄酯也进行了反应。用衍生自手性α-支化对-甲氧基苄醇的乙酸酯观察到高的非对映选择性。另外,据报道用Et 3 SiH作为还原剂进行催化还原。
benzyl cations (4‐MeOC6H4)CH+(CH2)nCHCH2 (1) have been generated laser‐flash photolytically in acetonitrile in the presence of enol ethers or 2‐methylfuran. The reactions of the cations 1 (n=2 and 4) with these π‐nucleophiles follow second‐order rate laws with rate constants comparable to those of the analogous saturated species (4‐MeOC6H4)CH+(CH2)3CH3. Product studies show the absence of cyclization
Branched-Selective Intermolecular Ketone α-Alkylation with Unactivated Alkenes via an Enamide Directing Strategy
作者:Dong Xing、Guangbin Dong
DOI:10.1021/jacs.7b08581
日期:2017.10.4
We describe a strategy for intermolecular branched-selective α-alkylation of ketones using simple alkenes as the alkylating agents. Enamides derived from isoindolin-1-one provide an excellent directing template for catalytic activation of ketone α-positions. High branched selectivity is obtained for both aliphatic and aromatic alkenesusing a cationic iridium catalyst. Preliminary mechanistic study