Pd(OAc)2 catalyzed synthesis of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles in imidazolium ionic liquids (ILs) without additives and with recycling/reuse of the IL
摘要:
A facile, high yielding, method for the synthesis of a library of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles from readily available Schiff bases is reported employing catalytic amounts of Pd(OAc)(2) in imidazolium ionic liquids (bmim)BF4 and (bmim)PF6 without ligands and/or additives. Simple product isolation and recycling/re-use of the IL are additional advantages of this method. (C) 2012 Elsevier Ltd. All rights reserved.
The synthesis of highly substituted β-lactams was achieved by addition of air-stable ethyl(trimethylsilyl)acetate derivatives to N-(2-hydroxyphenyl)aldimine sodium salts in a THF-EtCN mixture. This reaction proceeds with moderate to good yields and diastereomeric ratio of up to 78:22. The reactivity of the N-(2-hydroxyphenyl)aldimine can be modified by simply changing the co-solvent from EtCN to MeCN to afford the cyanomethylated addition product.
Neighboring phenolic group-activated <i>gem</i>-difluoroallylboration of imines for the catalyst-free synthesis of <i>gem</i>-difluorohomoallylamines
作者:Xing Yang、Feng Zhang、Yang Zhou、Yi-Yong Huang
DOI:10.1039/c8ob00541a
日期:——
We herein report an unprecedented addition reaction of pinacol gem-difluoroallylborates and imines enabled by a neighboring phenolic group in an N-protecting group under catalyst-free conditions, thus facilitating the construction of a wide range of racemic gem-difluorohomoallylamine derivatives. Based on the control experiments, a plausible transition state via the Zimmerman–Traxler model was proposed
Divergent synthesis of chiral heterocycles via sequencing of enantioselective three-component reactions and one-pot subsequent cyclization reactions
作者:Min Tang、Dong Xing、Haoxi Huang、Wenhao Hu
DOI:10.1039/c5cc01979f
日期:——
A highly efficient sequencing of enantioselective three-component reactions with a variety of one-pot subsequent cyclization reactions was developed.
利用一种高效的三组分选择性合成顺序,开发了一系列一锅法后续环化反应。
Microwave-Assisted Synthesis of Substituted Dibenzo[<i>b</i>,<i>f</i>][1,4]thiazepines, Dibenzo[<i>b</i>,<i>f</i>][1,4]oxazepines, Benzothiazoles, and Benzimidazoles
作者:Yu-Chin Lin、Ni-Ching Li、Yie-Jia Cherng
DOI:10.1002/jhet.2003
日期:2014.5
A highly efficient synthesis for possessing 7‐membered rings with two heteroatoms is described, using efficient microwave‐assisted one‐pot method to synthesize (substituted) dibenzo[b,f][1,4]thiazepines [1] and dibenzo[b,f][1,4]oxazepines [2] in high yields (up to 99%) by cyclocondensations of o‐aminothiophenol or o‐aminophenol with o‐halobenzaldehydes, o‐fluoroacetophenone, and o‐fluorobenzophenone
利用高效的微波辅助一锅法合成(取代的)二苯并[ b,f ] [1,4]噻氮平[1]和二苯并[ b ],描述了一种具有两个杂原子的7元环的高效合成方法。通过邻氨基硫酚或邻氨基苯酚与邻卤代苯甲醛,邻氟苯乙酮和邻氟二苯甲酮的环缩合,高产率(高达99%)的f ] [1,4]氧杂氮杂[2] 。在没有碱的情况下,邻氨基苯硫酚与邻卤代苯甲醛反应生成苯并噻唑。
Intramolecular Hydrogen Bonding. II. The Determination of Hammett Sigma Constants by Intramolecular Hydrogen Bonding in Schiff's Bases