Semioxamazones

Semioxamazide.—A gravimetric method for the estimation of cinnamic-aldehyde in cassia and cinnamon oils, but which appears to apply only to this aldehyde, has been devised by Hanus based on the formation of a crystalline semioxamazone when cinnamic aldehyde is treated -with semioxamazide, the reaction being—... 

Reaction CXXXl. Formation of Semioxamazones.—Semioxamazide, NH2.CO.CO.NH.NH2, possesses similar properties to semicarbazide, and reacts well with aldehydes, but with ketones the reaction does not seem to be generally applicable. 

Optical Resolution. This reagent is commonly used for the optical resolution of various compounds. Racemic spiro[4.4]nonane-1,6-dione was the first compound to be resolved (55% overall yield). The corresponding semioxamazone was obtained in optically active pure form in two or three recrystallizations and hydrolyzed to (—)-(5)-spiro[4.4]nonane-l,6-dione in a refluxing methanol-water mixture in the presence of Iodine (eq 2). 

In the field of arene tricarbonyl chromium complexes, racemic aldehydes can be resolved quantitatively by chromatographic separation of the corresponding semioxamazones. The first optical resolution was carried out on the semioxamazone made from the chromium tricarbonyl complex of o-anisaldehyde. - The separation of the diastereomers was done by silica gel... 

Dihydro-2-phenyl-4(l//)-quinolone has also been resolved by fractional crystallization of the corresponding chiral semioxamazones (eq 5). ... 

The semioxamazone is prepared by refluxing a mixture of 0.04 mole of 3, 0.04 mole of aldehyde 1, and 0.5 g of p-toluenesulfonic acid in 400 mL of anhydrous benzene until no starting aldehyde can be detected by TLC (about 10 minutes for 4b). Pre-coated TLC plates (silica gel 60 F-254, eluent diethyl ether/ hexane 90/10). The benzene is removed on a rotary evaporator and a red-orange, solid crude product is obtained, which is a —50 50 mixture of the diastereomers. 

The pure semioxamazone (0.07 mole) is refluxed in 100 mL of a 60/40 mixture of toluene/benzene and 50 mL of 60% (by volume) H2S04.t The progress of the reaction can be followed conveniently by TLC. After cooling the solution, the aqueous phase is decanted and the organic phase is washed three times with 50 mL of 10% sodium carbonate and then with 20 mL of water until the washings are neutral. The organic layer is dried over sodium sulfate, the solvent evaporated, and the crude aldehyde product chromatographed on silica gel. 

CrN305C2]H , Chromium, tricarbonyl[n6-2-methylbenzaldehyde 5-(a-methylbenzyl)semioxamazone]-, 23 87 CrN306C2 H 9, Chromium, tricarbonyl(ti -2-methoxybenzaldehyde 5-(a-methylbenzyl)semioxamazone]-, 23 88 CrN307C22H21, Chromium, tribarbonyl[Ti6-2,3-dimethoxybenzaldehyde 5-(a-methylbenzyl)semioxamazone]-, 23 88... 

Nj02C,8H Benzaldehyde, 2-methyl-, 5-(a-methylbenzyl)semioxamazone, chromium complexes, 23 87 N203Ci8H,9, Benzaldehyde, 2-methoxy-, 5-(a-methylbenzyl)semioxamazone, chromium complexes, 23 87... 

Semioxamazone pale yellow needles from HjO. M.p. 249 0° deconip. Insol. EtOH.. Phenylhydraztme m.p. 129-1°. p-NUrophenyViydrazone red needles from EtOH. M.p.. 234°. Insol. HgO. 4... 

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