Access to 1<i>H</i>-indazoles, 1<i>H</i>-benzoindazoles and 1<i>H</i>-azaindazoles from (het)aryl azides: a one-pot Staudinger-aza-Wittig reaction leading to N–N bond formation?
methides. Additional methyl groups in the benzylic position, however, do not promote a photochemical conversion into iminoquinone methides. If the benzylic substituent itself is part of a ring system, the size of this ring plays an important role. Thus, 2-methyl-8-nitrenotetrahydroisoquinoline rearranges very easily, whereas 4-nitrenophthalan does not give the reaction. Density functional calculations [B3LYP/6-31G(d)]
已经使用基质分离光谱和密度泛函计算研究了一系列邻甲苯基叠氮化物衍生物的光化学,这些衍生物在苄基位置带有多种取代基。已经发现,引入具有孤对的任何取代基(即,R = Br、Cl、MeO、Me2N)允许发生 1,4-氢转移,产生亚氨基醌甲基化物。然而,苄基位置的额外甲基不会促进光化学转化为亚氨基醌甲基化物。如果苄基取代基本身是环系统的一部分,则该环的大小起着重要作用。因此,2-甲基-8-硝基四氢异喹啉很容易重排,而4-硝基邻苯不会发生反应。密度泛函计算 [B3LYP/6-31G(d)] 已用于了解反应。已经发现活化能强烈依赖于取代基的性质,如果 R = NMe2 则最低。将苄基取代基并入环会降低系统的灵活性并导致障碍显着增加。
1,5-(H, RO, RS) shift/6π-electrocyclic ring closure tandem processes on N-[(α-heterosubstituted)-2-tolyl]ketenimines: a case study of relative migratory aptitudes and activating effects
A number of N-aryl ketenimines, substituted at the ortho position either with different non-cyclic acetalic functions (acetals, monothioacetals, dithioacetals) or with only one alkoxymethyl or (alkylthio)methyl group, have been prepared and submitted to thermal treatment in toluene solution. Under smooth heating the ketenimines bearing non-cyclic acetals converted into 3,4-dihydroquinolines following