使用HBPin和各种质子试剂作为氢源,已经开发了一种普遍,简单而有效的不饱和键转移加氢方法。包括烯烃,炔烃,芳族杂环,醛,酮,亚胺,偶氮,硝基,环氧和腈化合物在内的所有底物均应用于该催化体系。可以容忍在Pd / C / H 2组合下无法生存的各种基团。研究了反应物的活性,其变化趋势为:苯乙烯>二苯基甲亚胺>苯甲醛>偶氮苯>硝基苯>喹啉>苯乙酮>苄腈。还研究了带有两个或多个不同不饱和键的底物,并以优异的化学选择性发生了转移氢化。由Pd(OAc)2和HBPin生成的二氧化钛极大地提高了TH效率。此外,使用D 2 O和HBPin通过原位HD生成和区分,实现了末端芳族烯烃的化学选择性抗Markovnikov加氢氘。
Aliphatic and aromatic acetals are easily and efficiently converted to the corresponding nitriles by reaction with hydroxylamine hydrochloride in refluxing absolute ethanol.
脂肪族和芳香族缩醛在回流的无水乙醇中,可通过与盐酸羟胺反应,容易且高效地转化为相应的腈类化合物。
Cobalt-catalyzed cross-coupling reactions of alkyl halides with aryl Grignard reagents and their application to sequential radical cyclization/cross-coupling reactions
Reactions of alkyl halides with arylmagnesium bromides in the presence of cobalt(II)(diphosphine) complexes are discussed. Treatment of 1-bromooctane with phenylmagnesium bromide with the aid of a catalytic amount of CoCl2(dppp) [DPPP=1,3-bis(diphenylphosphino)propane] yielded octylbenzene in good yield. The reaction mechanism would include single electron transfer from an electron-rich cobalt complex
Mild and chemoselective catalytic deprotection of ketals and acetals using cerium(IV) ammonium nitrate
作者:Ali Ates、Arnaud Gautier、Bernard Leroy、Jean-Marc Plancher、Yannick Quesnel、Jean-Christophe Vanherck、István E Markó
DOI:10.1016/j.tet.2003.03.002
日期:2003.11
Cerium(IV) ammonium nitrate (CAN) is a powerful, though mild, reagent for the efficient and selective removal of a range of ketals and acetals. This novel deprotection method requires only catalytic amounts of CAN and tolerates a variety of functional and protecting groups. Mechanistic insights suggest that the Ce(IV) salts act as unique Lewis acids and not as redox active species.
A Mild, Chemoselective Protocol for the Removal of Thioketals and Thioacetals Mediated by Dess−Martin Periodinane
作者:Neil F. Langille、Les A. Dakin、James S. Panek
DOI:10.1021/ol027518n
日期:2003.2.1
development of a useful procedure for the removal of thioacetals and thioketals using Dess-Martin periodinane (DMP) reagent. In contrast to existing methods, this protocol offers general reactivity, compatibility with a wide range of functional groups, and convenient reaction times. Also discussed are chemoselectivity experiments involving functionalities that may be subject to oxidation by DMP, qualitative
Selective, Convenient and Efficient Deprotection of Trimethylsilyl and Tetrahydropyranyl Ethers, Ethylene Acetals and Ketals with Oxone under Non-aqueous Conditions
An efficient and selective method for the deprotection of trimethylsilyl (TMS) and tetrahydropyranyl (THP) ethers, ethylene acetals and ketals to their corresponding alcohols and carbonyl compounds using oxone in refluxing acetonitrile is described. Excellent chemoselectivity of this method makes it a useful and practical procedure in organic synthesis.