Benzaldehyde hydrazone

Benzaldehyd -hydrazon X/2,119 (aus den Azin) E14b, 508 (Umhydra-zonier.)... 

Cleavage of the ethylene bridge of herbicidally active N-(benzylideneamino) derivatives containing the imidazolidin-2-one ring results in inactivity as shown by the inability of benzaldehyde 2,4-dimethylsemicarbazones and benzaldehyde hydrazones derived from methyl hydrazinecarboxylate to inhibit plant growth. 

A variety of aldehyde hydrazones were screened [24b]. Branching at a saturated a carbon was detrimental in the tin mediated radical additions, but an aromatic benzaldehyde hydrazone 12 offered some success, with yields ranging from 30 to 83% (Table 2.3, entries 5 8). With the exception of 8a, which decomposed under the reaction conditions, the reactions were quite dean. Even in the examples with lower yields, the mass balance after recovery of the hydrazone precursor was generally 80 90%, demonstrating the excellent chemoselectivity of the reactions of radicals with N acylhydrazones. We were delighted to find that the radical additions had occurred with excellent stereocontrol in all secondary and tertiary radical additions to hydrazones 8 and 12 (Table 2.3), with diastereomer ratios ranging from 93 7 to 99 1 [24]. 

Wird bei der Herstellung der 2-Azido-benzaldehyd-hydrazone bzw. 2-Azido-l-(1-hydxazono-alkyl)-benzole der Aldehyd bzw. das entsprechende Keton vorgelegt und nur mit einem halben Aquivalent Hydrazin-Hydrat umgesetzt, so entstehen die entsprechenden Azine, die dann ther-molytisch zu 2,2 -Bi- cyclisiert werden kotinen211-294 z. B. ... 

Trotzder voraberwahntenNebenreaktionenkonneninEinzclfallen Aldehyd-hydra-zone mit Palladium/Kohle oder Platin(IV)-oxid zu Alkyl-hydrazinen hydriert werden z. B. erhalt man aus Benzaldehyd-hydrazon in Athanol mit Palladium/Kohle (5%) (2071... 

Oxidation of benzaldehyde hydrazone (193) brings about cyclization affording the thiazolo[2,3-c][l,2,4]triazole (194) (Equation (44)) <91KGS537>. Similarly, treatment of 2-[4-(ethoxy-carbonyl)thiazol-2-yl]hydrazones of aromatic aldehydes (193) with excess bromine induces bro-mination of the thiazole ring followed by ring-closure to form the bromo derivatives (195) <93KGS257>. 

Jason employed mercuric oxide oxidation of benzaldehyde hydrazone. Yates and Shapiro prepared phenyldiazomethane by basic cleavage of azibenzil. Bamford... 

A soln. of 1.2 moles benzaldehyde hydrazone in dimethylformamide added por-tionwise with stirring to a soln. of 6-diloro-l,3-dimethyl-5-nitrouracil in diloro-form, and refluxed ca. 1 hr. -> 5,7-dimethyl-3-phenyl-4,6(5H,7H)-pyrazolo[3,4-d]-pyrimidinedione. Y 77%. F. e. s. Y. Maki, K. Izuta, and M. Suzuki, Chem. Com-mun. 1971 y 1442 reactions of hydrazones, review, cf. Y. P. Kitaev and B. I. Buzykin, Russ. Chem. Rev. 41y 495 (1972) (Eng. transl.). 

Aldehyde hydrazones may be viewed as aza-enamines accordingly, benzaldehyde hydrazones undergo a Vilsmeier formylation38 ... 

Bromine added dropwise with stirring and ice-salt cooling under anhydrous conditions to a soln. of the equimolar amount of triphenylphosphine in abs. benzene, 2 moles of triethjdamine added to the suspension of the resulting triphenylphosphine dibromide, then a soln. of benzaldehyde hydrazone in abs. benzene added dropwise at room temp., and stirred 1 hr. benzaldehyde tri-phenylphosphazine. Y 89%. F. e. s. H. J. Bestmann and H. Fritzsche, B. 94, 2477 (1961). 

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