128591-43-5Relevant academic research and scientific papers
Derivation of Fluorine-Containing Pyridinedicarboxylates. III. Regio-selective Anion Chemistry at the 2- and 4-Position
Chupp, John P.,Molyneaux, John M.
, p. 1771 - 1780 (2007/10/02)
In contrast of Part II of the series, 4-alkyl-2-(difluoromethyl)-6-(trifluoromethyl)-3,5-pyridinedicarboxylates, 1, were reacted with various strength bases to effect regio-selective reaction of electrophiles at either the benzylic carbanion of the 4-position, or at the 2-(difluoromehyl)carbanion.Weaker bases up to and including potassium butoxide or lithium bis(trimethylsilylamide) effected reaction of 1 at 4-position to produce 2 and 3 by Stobbe-type condensations of aldehydes and ketones.In similar manner carbon disulfide, carbon dioxide, alkyl halides, silyl halides, and hexachloroethane produced the highly functionalized derivatives 4-10.In contrast, use of lithium diisopropylamide and like bases selectively effected carbanion formation at the 2-position to form, with the cited electrophiles and others, substitution products 11.The latter were further derived to the highly functional materials, 12-19.
