Oxidative dimerization of diethyl 3-thienylmalonate by high valent metal salts. Synthesis of benzo[1,2-b:4,5-b′]dithiophene derivatives
作者:Attilio Citterio、Roberto Sebastiano、Antonietta Maronati、Fabio Viola、Alessandra Farina
DOI:10.1016/0040-4020(96)00797-1
日期:1996.10
The oxidation of diethyl 3-thienylmalonate (1) by metal oxidants (Fe(ClO4)3, Mn(OAc)3, MnO2 and CuO) in various solvents at 60 °C affords dimerization products arising from side-chain and nuclear coupling of the intermediate delocalized malonyl radicals 6. Metal to sulphur binding is suggested to play a role in controlling the distribution of dimers 2 – 5. The higher thermodynamic stability of unsymmetric
2-噻吩丙二酸二乙酯(1)在60°C下于各种溶剂中被金属氧化剂(Fe(ClO 4)3,Mn(OAc)3,MnO 2和CuO)氧化产生的二聚化产物是由侧链和核偶联产生中间离域丙二酸基6。建议金属与硫的结合在控制二聚体2 – 5的分布中发挥作用。不对称二聚体3的较高热力学稳定性,以及其氧化性的分子内1,6-环化为4,使得可以开发新的简单合成苯并[1,2-b:4,5-b']二噻吩衍生物15-18。