Product Class 5: Azaindolizines with Two Nitrogen Atoms in the Five-Membered Ring

Abstract

In contrast to Section 12.5.1.1.1.1, where in most cases the first reaction step is the quaternization of a pyridin-2-amine derivative followed by nucleophilic attack of the 2-amino group on an appropriate functional group to form the imidazole ring, several ring closures have been elaborated starting from substituted pyridin-2-amines. In these cases, the â-carbon atom of the carbon chain attached to the 2-amino group bears an appropriate functional group, and a nucleophilic attack of the pyridine ring nitrogen atom at this center results in formation of the imidazole ring. Such syntheses are shown in Scheme 8.