Synthesis ( IF 2.2 ) Pub Date : 2020-08-25 , DOI: 10.1055/s-0040-1707230 Mieczysław Mąkosza 1 , Małgorzata Bechcicka , Krzysztof Wojciechowski
Abstract
Acetals of dimethyl phenyl- and heteroaryl-α-hydroxymethanephosphonates were deprotonated to generate carbanions, which enter the vicarious nucleophilic substitution (VNS) of hydrogen in aromatic nitro compounds to form 4-nitrobenzhydrylphosphonates and α-heteroaryl-4-nitrobenzylphosphonates. Similarly acetals of cyanohydrins of heteroaromatic aldehydes (furfural and 2-formylthiophene) react to form heteroaryl 4-nitroarylacetonitriles. The anion of the hemiacetal of acetaldehyde is an efficient leaving group in the base-induced β-elimination step – the crucial step in the VNS reaction. The reaction selectively occurred at the para-position to the nitro group.
中文翻译:
通过取代亲核取代(VNS)反应简单合成硝基二苯甲基膦酸二甲酯和杂芳基硝基芳基乙腈
摘要
将二甲基苯基和杂芳基-α-羟基甲烷膦酸酯的缩醛去质子化以生成碳负离子,碳负离子进入芳族硝基化合物中的氢的亲核取代基(VNS),形成4-硝基苯甲酰基膦酸酯和α-杂芳基-4-硝基苄基膦酸酯。类似地,杂芳族醛(糠醛和2-甲酰基噻吩)的氰醇缩醛反应形成杂芳基4-硝基芳基乙腈。乙醛半缩醛的阴离子是碱诱导的β-消除步骤(VNS反应的关键步骤)中的有效离去基团。该反应选择性地发生在硝基的对位。