Vilsmeier formylation of tert-anilines: dibenzo[b,f ][1,5]diazocines and quinazolinium salts via the ‘t-amino effect’1
作者:Ying Cheng、Otto Meth-Cohn、David Taylor
DOI:10.1039/a708799c
日期:——
e is used as the Vilsmeier reagent, normal formylation is observed, while use of aliphatic Vilsmeier reagents such as DMF and N-formylmorpholine give quinazolinium salts 16 and 17, also by way of the ‘t-amino effect’. The key feature in these formylations is the hydride transfer from the α-position of a tertiary amine to an unsaturated ortho-substituent CHNR2+, the ‘t-amino effect’.
所尝试的维尔斯迈尔邻的-formylation p取代Ñ,Ñ -dimethylanilines 1 ñ甲酰基Ñ -alkylarylamides 2意外地给出了二苯并[ b,˚F ] [1,5] diazocines 5在26-74%的产率。该反应通过Vilsmeier甲酰化至邻位1的二甲氨基进行,然后氢化物从N-甲基迁移到新形成的亚胺基CH基团,然后进行分子内环化,这是“ t-氨基效应”的一个新例子。循环的类似甲酰化叔-苯胺,例如4-甲苯基吡咯烷6a,e,g,-哌啶6b,f,h,-过氢a庚因6c,i和-吗啉6d,但化学性质不同,主要产物二甲酰化的烯胺7(12– 60%)。在某些情况下,还会分离出少量在氮原子上带有取代苄基的重氮电影8(1-13%)和N-甲酰化的重氮电影9。当使用N-甲酰基-1,2,3,4-四氢喹啉作为Vilsmeier试剂时,可以观察到正常的甲酰化作用,而使用脂族Vil