conjugate additions to aliphatic (E)-nitro alkenes 2a–j were carried out in good yields (35-87%) and excellent diastereomeric excesses (de = 94–≥98%). After reduction of the nitro group and protection of the amino function (11a–h, 73-87%, both steps), the cleavage of the auxiliary occurred without epimerisation (69-99%) using Na/NH3. The Boc-protected 2-amino alcohols 12a–h could be obtained in good overall
报告了第一个分子间不对称 oxa Michael 加成物,在氢氧化物源中具有可去除的手性信息。由于使用对映纯氧亲核试剂作为手性氢氧化物等价物 N-甲酰基去甲麻黄碱 (7) 并且以良好的产率 (35-87%) 和优异的非对映体过量 (de = 94–≥98%)。在还原硝基和保护氨基官能团(11a-h,73-87%,两个步骤)后,使用 Na/NH3 进行辅助裂解,没有差向异构化(69-99%)。Boc 保护的 2-氨基醇 12a-h 可以以良好的总产率(30-58%,四步)和优异的非对映体和对映体过量(de,ee = 94-≥98%)获得。
Rapid and Selective Formylation With Pentafluorophenyl Formate
作者:Lajos Kisfaludy、László Ötvös, Jr.
DOI:10.1055/s-1987-27987
日期:——
Pentafluorophenyl formate reacts smoothly with N-nucleophiles under mild conditions to give the N-formyl derivatives, whereas O- and S- nucleophiles remain unaffected even in the presence of a tertiary base.
A Process for the Preparation of R-(-)-N, Alpha-Dimethylphenethylamine (Levmethamfetamine) or S-(+)-N, Alpha-Dimethylphenethylamine (Methamphetamine) from D-Ephendrine, or L-Ephedrine Respectively
申请人:Gollapudy Subrahmanyam
公开号:US20080293971A1
公开(公告)日:2008-11-27
A process for synthesis of R-(−)-N,α-Dimethylphenethylamine (Levmetamfetamine, formula I), or S-(+)-N,α-Dimethyl phenethylamine (Methamphetamine, formula II), from d-ephedrine of formula III or l-ephedrine formula IV, the process comprising the steps of (a) acylating the d- or l-ephedrine base of formula III or formula IV with an acylating agent to make a reaction mixture containing a N-acylated ephedrines of formula V or formula VI; (b) deoxygenation of N-acylated ephedrines to make the compound of the formula VII or Formula VIII by using Raney Nickel catalyst; and (c) acid hydrolysis of the above deoxygenated products to get the levmetamfetamine or methamphetamine.