Methylenecarbonyl

The high acidity of ct-nitroketones makes it possible to perform the Henry reacdons or Michael addidons under extremely rruld condidons The reacdon proceeds in the presence of catalydc amounts of Ph-vP to give the C-C bond formadon products under nearly neutral condidons Thus, 1,5-dicarbonyl compounds and ct-methylenecarbonyl compounds are prepared by the denitradon of ct-nitroketones, as shown in Eqs 7 67 and 7 68, respecdvely... 

Diels-Alder addition of 2-chloroacrylonitrile and dienes gives the expected adducts, e.g. (310), which may be converted via azide, isocyanate, and hydrolysis to the ketone (311) in good yield. This constitutes a method for 1,4-addition of the methylenecarbonyl unit (—CHgCO—) to dienes. Among the many 1,3-dipolar additions of olefins recently reported are the intramolecular nitrone-olefin cycloadditionse.g. (312) (313), and the... 

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