A Facile Solution Phase Combinatorial Synthesis of Tetrasubstituted Pyridines Using the Bohlmann—Rahtz Heteroannulation Reaction.

Abstract

Pyridine derivativesPyridine derivatives R 0380 A Facile Solution Phase Combinatorial Synthesis of Tetrasubstituted Pyridines Using the Bohlmann-Rahtz Heteroannulation Reaction. -Enamino ester (IV) and equimolar mixtures of three different alkynones are transformed into three-or tetrasubstituted pyridines in a single synthetic step by either heating in toluene in the presence of AcOH or by reflux in toluene in the presence of catalytic amounts of ZnBr 2 . The results are compared with those obtained by application of traditional two-step Bohlmann-Rahtz conditions. In all cases, complete pyridine libraries are generated with very low levels of impurities. The Lewis acid catalyzed heteroannulation reaction (conditions C) is successful for problematic alkynones with different reactivities. -(BAGLEY*, M. C.; DALE, J. W.; OHNESORGE, M.; XIONG, X.; BOWER, J.; J. Comb. Chem. 5 (2003) 1, 41-44; Dep. Chem., Cardiff Univ., Cardiff CF1 3TB, UK; Eng.) -Klein 21-127

Facile Diversity-Oriented Synthesis and Antitubercular Evaluation of Novel Aryl and Heteroaryl Tethered Pyridines and Dihydro-6H-quinolin-5-ones Derived via Variants of the Bohlmann–Rahtz Reaction

“…Among them, one-pot creation of 2,3,6-trisubstituted pyridines through the reaction of alkynones with 1,3-dicarbonyls under modified Bohlmann–Rahtz conditions is prominent one (Figure A) . Here, the functionalized alkynones and 1,3-dicarbonyls were custom synthesized and used as starting materials to annelate the trisubstituted pyridine system . β-Enaminones, because of the presence of ambident nucleophilic character of enamine moiety and the ambident elctrophilic character of enone moiety, turned out to be simple synthetic intermediates for the subject of the present synthesis (Figure B).…”