Intramolecular cyclization reactions of pyrimidinium cations
作者:A.E. Frissen、G. Geurtsen、A.T.M. Marcelis、H.C. van der Plas
DOI:10.1016/s0040-4020(01)85440-5
日期:1990.1
undergo intramolecularinverseelectrondemandDiels-Alderreactions into the corresponding annelated pyridine derivatives under considerably milder conditions than the corresponding neutral pyrimidines. Protonation of the pyrimidine ring also facilitates the intramolecularDiels-Alderreaction. Protonation of less activated pyrimidines leads, however, to products resulting from an intramolecular coplanar