Vilsmeier formylation of para-substituted tert-anilines results in dibenzo[1,5]diazocines or quinazolinium salts: a remarkable example of the ‘t-amino effect’
Vilsmeier formylation of para-substituted tert-anilines results in dibenzo[1,5]diazocines or quinazolinium salts: a remarkable example of the ‘t-amino effect’
作者:Otto Meth-Cohn、David L. Taylor
DOI:10.1039/c39950001463
日期:——
Formylation of para-substituted tert-anilines with various N-formylated sec-anilinesâ ; in phosphoryl chloride results in ortho-formylation followed by cyclisation of the iminium salt to the adjacent tert-amino α-position by way of the ât-amino effectâ giving dibenzo[b,f][1,5]diazocines; in a similar manner, with N-formylated sec-aliphatic amines, quinazolinium salts are formed while bulky formanilides give the expected ortho-formylated tert-aniline.
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-aminoeffect’. 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-aminoeffect’.