Mechanism of the inverse-electron demand Diels–Alder reaction of 2-aminopyrroles with 1,3,5-triazines: detection of an intermediate and effect of added base and acid
摘要:
In base, a 2-aminopyrrole reacted with a 1,3,5-triazine to give a zwitterion (Meisenheimer complex). Acid promoted its conversion to the pyrrolo[2,3-d]pyrimidine. A cascade mechanism with reversible steps is proposed to explain why both a base and an acid are needed for the cycloaddition to occur. (c) 2007 Elsevier Ltd. All rights reserved.
Effect of the leaving group on the reaction of 2-aminopyrroles with electron deficient heteroaromatic azadienes: substitution by addition–elimination versus cycloaddition
摘要:
When a good leaving group is present in the heteroaromatic azadiene, reaction with 2-aminopyrroles occurs by substitution by addition-elimination instead of cycloaddition. This novel reaction is sensitive to steric effects and takes place in 2-amino-1-methylpyrrole at C-5 and the exo amino group but at C-3 in 2-amino-1-t-butylpyrrole. (c) 2007 Elsevier Ltd. All rights reserved.