Diazomethanes reactions

A valuable extension of the diazomethane reaction for the preparation of A-homosteroids was discovered by Johnson, Neeman and Birkeland " who found that a,j5-unsaturated ketones are homologated by reaction with diazomethane in the presence of either fluoroboric acid or boron trifluoride. The main product is formed by the insertion of a methylene group between the carbonyl group and the unsaturated a-carbon to give a / ,y-unsaturated ketone. 

Johnson and co-workers also investigated the general acid-catalyzed diazomethane reaction with benzalacetone (20). When treated with 3 mole-equivalents of diazomethane, the latter is converted to the A -pyrazoline... 

Reviews dealing with a specific reaction or property from the heterocyclic point of view have been rarer—tautomerism (continued from Volume 1), free radical substitution, metal catalysts and pyri-dines, acid-catalyzed polymerization of pyrroles, and diazomethane reactions have been covered in this volume. 

Diazomethane, reaction with 2,4,6-tri-nitrobenzenesulfonic acid and dimethyl ether, 46,122 Diazonium xanthates, detonation of, 47, 107... 

Diazomethane, reaction with D-cam-phor-lO-sulfonyl chloride and triethylamine, 48,106 reaction with chloromethanesulfonyl chloride, 49,19... 

The stereoselectivity in the Grignard reaction,97 complementary to that in the methyllithium109 and diazomethane156 reactions, of methyl 3,4-0-isopropylidene-a-L-en/thro-pentopyranosid-2-ulose (62), and that between the Grignard and diazomethane reactions of the / ano-mer107 of 62, methyl 2,3-0-isopropylidene-/ -L-en/thro-pentopyranosid-... 

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