Metallkatalysierte zersetzung von 4-diazomethyl-4H-pyranen - ein neuer zugang in das oxepinsystem
作者:Karl-Ludwig Hoffmann、Manfred Regitz
DOI:10.1016/s0040-4039(00)87867-3
日期:——
Electrophilic diazoalkane substitution of lithiated diazomethyl compounds (5) with the pyrylium salt 4 leads to the formation of the hitherto unknown 4-diazomethyl 4H-pyranes 6. Their decomposition with catalytic amounts of μ-allyl palladium chloride (dimer) in benzene is followed by ring enlargement to the oxepines 8, which are not in equilibrium with the valence tautomeric benzene oxides 7.
用吡啶鎓盐4亲电重氮化锂化的重氮甲基化合物(5)导致形成迄今未知的4-重氮甲基4H-吡喃6。在催化量的α-烯丙基氯化钯(二聚体)在苯中分解后,随后分解环扩大至氧杂环丁烷8,其与价互变异构苯氧化物7不平衡。