A Highly Efficient Procedure for Regeneration of Carbonyl Groups from their Corresponding Oxathioacetals and Dithioacetals Using Sodium Nitrite and Acetyl Chloride in Dichloromethane
A Simple and Practical Synthetic Protocol for Acetalisation, Thioacetalisation and Transthioacetalisation of Carbonyl Compounds under Solvent-Free Conditions
作者:Abu T. Khan、Ejabul Mondal、Subrata Ghosh、Samimul Islam
Efficient Method for Thioacetalization of Carbonyl Compounds in the Presence of a Catalytic Amount of Benzyltriphenylphosphonium Tribromide (BTPTB) under Solvent-Free Conditions
作者:Abdol Reza Hajipour、Seied A. Pourmousavi、Arnold E. Ruoho
DOI:10.1080/00397910802219197
日期:2008.7.24
Abstract A variety of carbonylcompounds have been successfully converted to the corresponding thioacetal derivatives in good to excellent yields on reaction of carbonylcompounds with 1,2-ethanedithiole, 1,3-propanedithiol, and ethylthiol in the presence of a catalytic amount of benzyltriphenylphosphonium tribromide (BTPTB) under solvent-free conditions. Some of the major advantages of this method
The directing group wins over acidity: kinetically controlled regioselective lithiation for functionalization of 2-(2,4-dihalophenyl)-1,3-dithiane derivatives
Regioselective lithiation followed by functionalization of 2-(2,4-dihalophenyl)-1,3-dithiane derivatives with different electrophiles was achieved in good to excellent yields. When the title compound is treated with n-butyl lithium, lithiation occurs selectively at the aromatic carbon having less acidic proton despite the presence of thermodynamically more acidic 1,3-dithiane proton in the same molecule
区域选择性锂化,然后用不同的亲电试剂官能化2-(2,4-二卤代苯基)-1,3-二噻吩衍生物,收率良好至优异。当标题化合物用正丁基锂处理时,尽管在同一分子中存在热力学上更酸性的1,3-二噻吩质子,但在具有较少酸性质子的芳族碳上选择性地发生锂化。计算得出的p K a可用反应位质子的值和实验结果表明,2-(2,4-二卤代苯基)-1,3-二硫代烷衍生物的区域选择性锂化不受热力学酸性的控制,而仅由质子的动力学去除决定。芳香环中存在的1,3-二卤代取代基的协同配位作用(复杂诱导的邻近效应,CIPE)和诱导作用。通过使用这种区域选择性官能化,可以轻松地制备各种1,2,3,4-四取代的芳族化合物。
Nickel(II) chloride as an efficient and useful catalyst for chemoselective thioacetalization of aldehydes
作者:Abu T. Khan、Ejabul Mondal、Priti R. Sahu、Samimul Islam
DOI:10.1016/s0040-4039(02)02771-5
日期:2003.1
A wide variety of acyclic and cyclic dithioacetals can be prepared chemoselectively from the corresponding aldehydes by employing a catalytic amount of nickel(II) chloride in dry CH2Cl2-MeOH (5:1) at room temperature in good yields. Some of the major advantages of this procedure are high chemoselectivity, ease of operation, high yields and also compatibility with other protecting groups. (C) 2003 Elsevier Science Ltd. All rights reserved.
Khan, Abu T.; Mondal, Ejabul, Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2005, vol. 44, # 4, p. 844 - 850