Rh-catalyzed alkene oxidation: a highly efficient and selective process for preparing N-alkoxysulfonyl aziridines
作者:Kiran Guthikonda、Paul M. Wehn、Brian J. Caliando、J. Du Bois
DOI:10.1016/j.tet.2006.07.099
日期:2006.12
Unique alkoxysulfonyl aziridine heterocycles were prepared through selective intra- and intermolecular alkeneoxidation reactions. These methods are general and perform efficiently at low Rh-catalyst loadings (1–2 mol %) with only a slight excess of an inexpensive commercial oxidant, PhI(OAc)2. For intermolecular processes, trichloroethylsulfamate was identified as a novel and markedly effective N-atom
Directly opposing Keulemans rule! Phosphinites work as reversiblybounddirectinggroups allowing for the first highly regioselective hydroformylation of 3‐substituted homoallylic alcohols to construct quaternary carbon centers. This method enables the atom‐economical synthesis of a wide range of α,α‐disubstituted γ‐lactones and highly substituted tetrahydrofurans (see scheme; R1, R2=alkyl/aryl).
直接反对Keulemans统治!次膦酸盐作为可逆结合的导向基团起作用,从而允许3-取代均烯丙基醇的首次高度区域选择性加氢甲酰化以构建季碳中心。该方法可实现多种α,α-二取代的γ-内酯和高度取代的四氢呋喃的原子经济合成(参见方案; R 1,R 2 =烷基/芳基)。
A Concise Synthesis of (<i>S</i>)-γ-Fluoroleucine Ethyl Ester
作者:Christian Nadeau、Francis Gosselin、Paul D. O’Shea、Ian W. Davies、Ralph P. Volante
DOI:10.1055/s-2005-923593
日期:——
We report herein a six-step, chromatography-free, through-process for the asymmetric synthesis of (S)-γ-fluoroleucine ethyl ester sulfate salt (6) that proceeds in 25% overall yield from inexpensive ethyl glyoxylate. This approach features a Ti/Zn-catalyzed glyoxylate-ene reaction-olefin hydrofluorination-amine alkylation as key steps.