Hydrazine urazolate

Hexamminenickel(II) iodide, 3 194 Hydrates, nomenclature of, 2 264 Hydrazidicarbamide, 4 26 Hydrazine, 1 90 and derivatives, from hydroxyl-amine-O-sulfonic acid, 5 124 derivatives of, by reduction of A -nitrosohydroxylamine-Ar-sulfonates, 6 121 residues, recovery of, 1 92 Hydrazine dihydrochloride, 1 92 Hydrazine urazolate, formation of, in preparation of urazole, 5 53, 54... 

The reaction mixture is chilled to 0° in an ice-salt bath, and 2.9 g. of biurea (m.p. 245 to 246°) is filtered off. The filtrate is evaporated on a hot-water bath under reduced pressure (water aspirator) until a solid cake remains in the flask. The reaction cake is broken up and washed with 95% ethanol to give 110 g. (83%) of crude hydrazine urazolate (m.p. 195 to 196° with decomposition). The product can be purified with 86% recovery by dissolving it in hot water (2.5 ml./g.), filtering through a warm funnel, adding 95% ethanol to turbidity, and chilling. 

The 110 g. of hydrazine urazolate and 1 1. of acetone are placed in a 2-1. three-necked standard-taper flask equipped with a stirrer and reflux condenser. The suspension is stirred and heated for 2 hours, after which the mixture is chilled and the insoluble product removed by filtration. The product is washed well with acetone and finally air-dried. The product weighs 78 g. and melts at 244 to 246° with decomposition. This represents a 94% con-... 

NH2NH2-2HC1 Hydrazine dihydrochloride, 1 92 NH2NH2C2H3N302 Hydrazine urazolate, 5 53, 54 [NH2NH3JHS04 Hydrazonium hydrogen sulfate, 1 90, 92 NH2N02 Nitramide, 1 68, 72 NH2Na Sodium amide, 1 74, 2 80, 128... 

Triazole has been prepared by the oxidation of substituted 1,2,4-triazoles, by the treatment of urazole with phosphorus pentasulfide, by heating equimolar quantities of formyl-hydrazine and formamide, by removal of the amino function of 4-amino-l,2,4-triazole, by oxidation of l,2,4-triazole-3(5)-thiol with hydrogen peroxide, by decarboxylation of 1,2,4-triazole-3(5)-carboxylic acid, by heating hydrazine salts with form-amide,by rapidly distilling hydrazine hydrate mixed with two molar equivalents of formamide, i by heating N,N -diformyl-hydrazine with excess ammonia in an autoclave at 200° for 24 hours, and by the reaction of 1,3,5-triazine and hydrazine monohydrochloride. ... 

A robust catch, cyclize, and release preparation of 3-thioalkyl-1,2,4-triazoles mediated by the polymer-bound base P-BEMP has been described <02TL5305>. Reaction of solid-supported hydrazides 103 with isocyanates or isothiocyanates followed by base-induced cyclization/cleavage afforded 1,2,4-trisubstituted urazoles and thiourazoles 104 <02JCO491, 02TL3899>. Polymer-supported V-acyl-1 //-benzotriazole- 1-carboximidamides 105 reacted with hydrazines followed by acidic cyclizative release to give 3-alkylamino-l,2,4-triazoles 106 <02OL1751>. 

Methyl urazol 225 is oxidized into iV-methyl triazoline-3,5-dione with tert-butyl hypochlorite. Without isolation it reacts with ( )-penta-2,4-diene-l-ol giving adduct ( )-226 as a racemic mixture. On treatment of ( )-226 with a lipase (R/Novozym 435) in vinyl acetate 38% of ester (5)-227 (86% ee) and 29% of alcohol R)-226 (59% ee) is isolated. Epoxidation of (S)-227 provides 13% of (—)-228 and 68% of (—)-229. The latter epoxide is hydrolyzed under acidic conditions to provide 230 that reacts with hydrazine to give enantiomerically pure (—)-l-azafagomine (O Scheme 80) [394]. This compound has a slow binding inhibitor of almond /3-glucosidase Ki = 0.33 pM). A similar sequence of reactions converts (R)-226 into (+)-l-azafagomine. The latter is not an inhibitor of 8-glucosidases [395]. 

Urazoles represent a highly functionalized heterocyclic core, the synthesis of which is shown in Scheme 10. In the cases of N,N -diphenylhydrazine and unbranched aliphatic N,N -disubstituted hydrazines 37, carhonylimidazole Wang resin 36 was reacted at room temperature. N,N -Diisopropylhydrazine required elevated temperatures for complete conversion. The intermediate carbazate 38 was coupled to aromatic or aliphatic isocyanates to give the precursor 39 for cychzation. Cyclization was conducted with triethylamine/toluene at 110 °C or vrith KOtBu/ THF at 60 °C (18 h each) to give urazoles. The latter conditions are used especially for sterically crowded residues (e.g., IC = cyclohexyl). Using isothiocyanates in the... 

One of the serious disadvantages of the use of TADs is the difficulty of hydrolyzing such urazoles as 467. Very often the harsh conditions (strong base, high temperature) provide low yields of the cyclic hydrazines 468 and... 

---