Derivation of fluorine‐containing pyridine dicarboxylates. II . Elaboration at the 4‐position

In response to the bio‐activity found in fluorine‐containing 4‐alkyl‐3, 5‐pyridinedicarboxylates, a series of novel 4‐substituted derivatives, not directly available by Hantzsch sequences, were prepared. Starting 4‐alkylpyridines, 1 , were converted via enamine 2 to materials 3–8 . Derivatives 9–16 in turn were derived from aldehyde 3 , while acid derivatives 28–36 were prepared from 14 . Addition of oxygen, sulfur, and carbenoids effected conversion of 4‐allylpyridine 16 to epoxy and cyclopropyl derivative 16–22 . A number of neighboring group effects were noted, including those forming the fused‐ring systems 23‐27 .