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。