Methyleneammonium salts

If a substituent is not required in the 4-position of the new pyridine ring, then viable alternatives to the current procedure include trimethylhydrazonium-salt pyrolysis5 and various methods for condensing ketones or enamines with formaldehyde or methyleneammonium salts.43- -6 1 The latter methods often involve isolation of the intermediate 1,5-diketone, which is condensed with ammonia or... 

Treatment of em-dibromocyclopropanes with one equivalent of alkyllithium at low temperature generates 1-bromocyclopropyllithiums, which have proved to be very versatile intermediates for the synthesis of various cyclopropyl derivatives. Thus, the reactions of the bromolithium compounds with disulfides ketones, alkyl ha-lides , methyleneammonium salts and trimethylsilyl chloride provide the corresponding 1-bromocyclopropyl derivatives (equation 124). A neighbouring ether... 

The methyleneammonium salt (2) is a highly reactive Mannich reagent. It has been used to introduce a methyl group into the corrin nucleus. Thus stirring a solution of the corrin (3) in dichloromethane with (2) gives the pure 15-(dimethylamino)methyl derivative (4) in 85 % yield. This product (4) was converted into the 15-methylcorrin derivative (5) by catalytic hydrogenation.1... 

Mannich reaction with methyleneammonium salts CH C - CHnNC... 

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