1 -Methoxycarbonyl pyridinium chlorid

NMR spectra of the solution of 69j and 69k with p-TolLi show a remarkable upheld shift relative to those for 69j and 69k, AS = 182 and 212 ppm, respectively, indicating an increase in the coordination number of tin. It is noteworthy that the organos-tannates 69h and 69i react with l,3-bis(methoxycarbonyl)pyridinium chloride to give the corresponding alkylated(arylated) dihydropyridines. ... 

The action of alkynyl Grignard reagents on the pyridinium salt 67 affords solely 1,2-dihydropyridine derivative 68, whereas alkyl Grignard reagents yield mixtures of 1,2- and 1,4-dihydropyridines (equation 10). The contrasting behaviour of the two nucleophiles was explained by means of the Principle of Hard and Soft Acids and Bases". Application of the reaction to the action of the acetylenic Grignard compound 69 on l-methoxycarbonyl-2-methylpyridinium chloride gave the dihydropyridine derivative 70, which was transformed into ( ) -monomorine 71, a train pheromone of the pharao ant. ... 

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