DDQ-Mediated Oxidative Coupling: An Approach to 2,3-Dicyanofuran (Thiophene)

A facile
oxidative coupling of α-carbonyl radicals to 2,3-dichloro-5,6-dicyanobenzoquinone
(DDQ) for the synthesis of 2,3-dicyanofurans and thiophenes starting
from readily available β-diketones, simple ketones, and β-keto
thioamides in up to 95% yield in one step was developed. Mechanistic
investigations revealed that a radical process could be involved in
this transformation, and a water promoted C–C bond cleavage
pathway is proposed for the formation of 2,3-dicyanofurans and thiophenes.

本研究开发了一种简便的氧化偶联方法：以易得的β-二酮、简单酮及β-酮硫代酰胺为起始原料，通过α-羰基自由基与2,3-二氯-5,6-二氰基苯醌（DDQ）的氧化偶联反应，一步法合成2,3-二氰基呋喃与噻吩类产物，产率最高可达95%。机理研究表明该转化涉及自由基历程，并提出了水促进的C-C键裂解路径以生成2,3-二氰基呋喃与噻吩类产物。