The reactivity of 2-vinylindoles with dimethyl acetylenedicarboxylate
1984; Elsevier BV; Volume: 40; Issue: 23 Linguagem: Inglês
10.1016/s0040-4020(01)91317-1
ISSN1464-5416
AutoresRichard A. Jones, Pilar M. Fresneda, Teresa Aznar Saliente, J. SEPULVEDA ARQUES,
Tópico(s)Fluorine in Organic Chemistry
ResumoThe overall rates of reaction of 1-substltuted-1- (1-methyl-2-indolyl)ethenes with dimethyl acetylenedicarboxylate are considerably lower than those of the corresponding 2-vinyl- pyrroles. Steric interaction between the N-methyl group on the indole ring and the 1-substituent on the ethenyl group prevents the diene system adopting a coplanar cisoid configuration and, thereby, inhibits the π4 + π2 cycloaddition reaction of the system with dimethyl acetylenedicarboxylate. Under such conditions, the indolylethene preferentially undergoes a Michael addition reaction at the 3-position. The π4 + π2 cycloaddition reaction is promoted at elevated temperatures. No evidence was found for a Cope rearrangement of the Michael adducts to give the dihydrocarbazole.
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