Glyoxal methyl-, phenylhydrazone

As the reaction sequence of Scheme 12-38 can be stopped at the stage of the oo-methylglyoxal phenylhydrazone (12.78), it is possible to synthesize asymmetrically substituted formazanes (12.80, Ar = Ar ) by reacting acetone with one equivalent of a diazonium ion ArNJ under acidic conditions and then coupling the co-methyl-glyoxal phenylhydrazone with Ar NJ in alkaline solution. 

Treatment of methyl sulfoxide solutions of D-mannose or other sugar phenylhydrazones or melibiose phenylosazone with potassium tert-butoxide and a trace of oxygen at room temperature showed no evidence of the paramagnetic species characteristic of glyoxal bis(phenylhydra-... 

Oxime (96) and phenylhydrazone (97) are also formed from 6-acetyltrithiadiazepine (77). The methyl group of (77) was oxidized to give trithiadiazepinyl glyoxal monohydrate (98) (Scheme 25) <91JCS(P1)2945>. 

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