Hydrazines from azines

Nickel/formic acid/triethylamine Hydrazines from azines... 

Hydrazido(2-) and hydrazido(l-) complexes have also been shown to condense with aldehydes and ketones to give diazoalkane complexes containing the W=N—N=CRiR2 unit.387,388 Treatment of these complexes with LiAlFL, gives secondary amines and ammonia, whereas treatment with acid produces hydrazine, keto azines and N2-free tungsten compounds. Amines can also be produced from organohydrazido(2—) complexes.389,390... 

Hydrazones. A useful procedure for preparation of hydrazones free from azines is exemplified by the preparation of acetone hydrazone.1 Acetone is first converted into acetone azine (b.p. 128-131°) by reaction with 100% hydrazine hydrate and potassium hydroxide this product is then converted into acetone hydrazone by reaction with anhydrous hydrazine2 and sodium hydroxide. 

The reductive removal of hydrazine substituents under oxidising conditions from azines and some azoles is conceptually related to oxidative removal of thiols (e.g. 29.1.1.2). In this case, the intermediacy of a diimide seems likely, as illustrated below. ... 

Azines, Aldehydes react with hydrazine to yield azines the reaction cannot usually be arrested at the hydrazone stage. This reaction may be illustrated by the preparation of bevzalazine from benzaldehyde ... 

The problem of the synthesis of highly substituted olefins from ketones according to this principle was solved by D.H.R. Barton. The ketones are first connected to azines by hydrazine and secondly treated with hydrogen sulfide to yield 1,3,4-thiadiazolidines. In this heterocycle the substituents of the prospective olefin are too far from each other to produce problems. Mild oxidation of the hydrazine nitrogens produces d -l,3,4-thiadiazolines. The decisive step of carbon-carbon bond formation is achieved in a thermal reaction a nitrogen molecule is cleaved off and the biradical formed recombines immediately since its two reactive centers are hold together by the sulfur atom. The thiirane (episulfide) can be finally desulfurized by phosphines or phosphites, and the desired olefin is formed. With very large substituents the 1,3,4-thiadiazolidines do not form with hydrazine. In such cases, however, direct thiadiazoline formation from thiones and diazo compounds is often possible, or a thermal reaction between alkylideneazinophosphoranes and thiones may be successful (D.H.R. Barton, 1972, 1974, 1975). 

Hydrazones are formed from mono- and Ai,A/-disubstituted hydrazines. Hydrazine itself can give either hydrazones or azines, depending mainly on the ratio of carbonyl component to hydrazine. The ease of formation of these compounds depends on the nature of the carbonyl constituent ... 

Chloroquinoline (401) reacts well with potassium fluoride in dimethylsulfone while its monocyclic analog 2-chloropyridine does not. Greater reactivity of derivatives of the bicyclic azine is evident also from the kinetic data (Table X, p. 336). 2-Chloroquinoline is alkoxylated by brief heating with methanolic methoxide or ethano-lic potassium hydroxide and is converted in very high yield into the thioether by trituration with thiocresol (20°, few hrs). It also reacts with active methylene carbanions (45-100% yield). The less reactive 3-halogen can be replaced under vigorous conditions (160°, aqueous ammonia-copper sulfate), as used for 3-bromoquino-line or its iV-oxide. 4-Chloroquinoline (406) is substituted by alcoholic hydrazine hydrate (80°, < 8 hr, 20% yield) and by methanolic methoxide (140°, < 3 hr, > 90% yield). This apparent reversal of the relative reactivity does not appear to be reliable in the face of the kinetic data (Tables X and XI, pp. 336 and 338) and the other qualitative comparisons presented here. 

Hydrazine is hypergolic with cone, nitric acid [1]. Of a series of hydrazones and azines derived from aldehydes and ketones, only those which decomposed when heated alone were hypergolic with the acid when heated at 12.5°C/min [2], Solid hydrazones formed from various aldehydes with dimethylhydrazine or phenylhydrazine are hypergolic with the acid [3],... 

This silyl hydrazone formation-oxidation sequence was originally developed as a practical alternative to the synthesis and oxidation of unsubstituted hydrazones by Myers and Furrow [31]. The formation of hydrazones directly from hydrazine and ketones is invariably complicated by azine formation. In contrast, silyl hydrazones can be formed cleanly from /V,/V -bis(7< rt-butyldimethylsilyl)hydrazine and aldehydes and ketones with nearly complete exclusion of azine formation. The resulting silylhydrazones undergo many of the reactions of conventional hydrazones (Wolff-Kishner reduction, oxidation to diazo intermediate, formation of geminal and vinyl iodides) with equal or greater efficiency. It is also noteworthy that application of hydrazine in this setting may also have led to cleavage of the acetate substituents. 

Alkyl-3-formylcarbazoles form-arylhydrazones " and azines or hydrazones with hydrazine. 9-Ethyl-3-formylcarbazole gives Schiflf bases with arylamines. Variously substituted 3-formylcarbazoles condense with aminoacetal, " and the resulting imines are easily reduced catalytically or with sodium borohydride. Anils from... 

The most extensively investigated 1,2-diazocines are 3,4,5,6,7,8-hexahydro derivatives, of interest in connection with studies on the properties of cyclic azo compounds. These compounds are obtained from the hydrazines (159) usually not isolated, by oxidation with yellow mercury(II) oxide. 3,8-Diaryloctahydrodiazocines are prepared by reduction of the azines dialkyl and unsubstituted derivatives are obtained by hydrolysis of the N,N-bis(ethoxycarbonyl) compounds (69JA3226,70JA4922). Cyclization of 2,7-diaminooctane with IFs gave the 3,3,8,8-tetramethyl compound (78CB596). 

The azines represent another class of organic compounds which, in principle, should be reducible to azo compounds. The method is attractive since, with the availability of anhydrous hydrazine, azines are readily prepared from a wide variety of ketones and aldehydes. Evidently, introduction of 1 gram-molecule of hydrogen into an azine molecule has only recently been accomplished (see Section 6, Procedure 8) [73], Two preparations involving the 1,4-addition of chlorine to an azine system have been carried out and are illustrated here. 

A cold solution of BrF3 (0.3 mL. 6 mmol) in CC13F (25 mL) was added over 10 min to a CCI3F solution of adamantanone azine (3 mmol) prepared from adamantanone and hydrazine in stoichiometric proportions. An immediate reaction took place giving the desired product yield 95%. 

Since it may undergo reaction with benzaldehyde in the subsequent step to give benzaldehyde azine, it is advisable to remove the last traces of hydrazine by rotating the flask under reduced pressure. The submitters used an oscillating motor which operates on compressed air or vacuum and is commonly employed with Kugelrohr distilling units. One such motor is available from the Aldrich Chemical Company, Inc. 

The reaction of azines 107, prepared in situ from aldehydes or ketones and hydrazine, afforded the Ugi adducts 108. The acid treatment of 108 resulted in the hydrolytic cleavage of the imino group with formation of the hydrazides, which immediately cyclized to phthalazinone amides 109 (Scheme 2.39) [70]. 

Bifunctional 1,2,3-dithiazole 13 bridged by an azine spacer has been prepared from Appel salt 20 and hydrazine, with a goal to determine the extent of communication between the two dithiazole rings as a function of the electronic and steric demands of the bridge (Equation 29) (see Section 6.01.2) <2001IC2709>. 

Starting from isolated hydrazones, reduction to the corresponding hydrocarbons by treatment with base in an aprotic solvent takes place at temperatures significantly below the 200 °C of the Huang-Minlon modification of the Wolff-Kishner reduction. However, hydra-zones cannot be prepared in a one-step reaction between a ketone and hydrazine, since usually azines (R1R2C=N=N=CR1R2) are formed instead. However, semicarbazones are hydrazone derivatives that are easily accessible by the reaction of a ketone with semicarbazide (for the mechanism, see Table 9.2). Semicarbazones can be converted into alkanes with KO/Bu in toluene at temperatures as low as 100 °C. This method provides an alternative to the Wolff-Kishner reduction when much lower than usual reduction temperatures are desirable. 

Starting from previously isolated hydrazones, it turns out that they can be reduced to the corresponding hydrocarbons by treatment with base in an aprotic solvent at temperatures significantly below the 200°C of the Huang-Minlon modification of the Wolff-Kishner reduction. However, hydrazones cannot be prepared in a one-step reaction between a ketone and hydrazine, since usually azines... 

---