Pyridines, carbanions from methyl derivatives

It has also been found that the reaction of a-keto-ketene dithioacetals (8) with the carbanions derived from methyl ketones (9) gives unsaturated 1,5-dicarbonyl compounds (10). The latter compounds can be ring-closed to pyridines (11) by treatment with ammonium acetate. ... 

Full details have been published of the synthesis of pyridines derived from the 1,5-dicarbonyl compounds resulting from the reaction of -ketoketene dithioacetals with the carbanions obtained by deprotonation of methyl ketones. 5 There have been two reports of the synthesis of pyridines from enamines and malononitrile.26,27 This route is exemplified by the conversion of the readily available enamines (10 Z=0 or S) into the 2-araino-3-cyanopyridines (11) ... 

In order to obtain well-defined AB diblock copolymers by anionic polymerization and sequential monomer addition, some crucial conditions must be fulfilled (1) the carbanion formed by the second monomer must be more, or at least equally, stable than the one derived from the first monomer, and (2) the initiation of polymerization of the second monomer by the anion of the first monomer must be higher than the rate of propagation of monomer B. To fulfill these requirements, the monomers used must be added sequentially in the order of increasing electron affinity (e.g., a-methyl styrene (aMeSt) < St butadiene (Bd)< vinyl pyridine < methyl methacrylate (MMA)) and the nucleophilicity of the intermediate macromolecular carbanion A formed should at least match (though... 

The synthesis was achieved by copper(I)-catalysed addition of the carbanion derived from a methyl pyridine 9.229 to an unsaturated (3-ketoester 9.230, trans to the existing methyl substituent (Scheme 9.63). Ring closure... 

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