Amines from azines

Amines from azines and hydrazo compounds with hydrogenation of carbon-carbon double bonds... 

Few examples of N-amination of azines have been reported. The use of such reagents as 0-mesitylenesulfonylhydroxylamine has led to the direct synthesis of /V-aminopyridazinium, -pyrimidinium, and -pyrazinium salts (80CPB2676), and 1-aminobarbituric acids (72CPB1814), while 0-(2,4-dinitrophenyl)hydroxylamine was a useful amino-transfer reagent in the direct synthesis of 1 -amino-6-methylthio-1,2,4-triazin-4( 17/)-ones from 2-methylthio-1,2,4-triazin-5( 1H)-ones (82JHC1583). 

Ar. amines from cyclic ketones via hydroaromatic azines... 

This reaction through formation of an azine opens a new route to primary amines from ketones and presents several real interests. In case of IPDA, the global yield is about 93 % and for the first time byproduction of impurities is lowered while using mild conditions. The most convenient catalyst for the hydrogenation step is a simple Raney nickel contrary to the classical process which often uses more sophisticated catalysts. 

A search has not been made for products of displacement of halogen from the benzo-ring in polyhalo compounds, but it is clear that the major mono-substitution occurs in the azine ring. For example, 2,6- and 2,7-dichloroquinoxalines give 70-80% of the 2-amination product with )S-diethylaminoethylamine (150°, 2 hr) or y-(l-piperidyl)-propylamine (220°, 2 hr). 2,3,6-Trichloroquinoxaline gives with... 

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... 

Azine approach. Oxazolo[3,2-a]pyridinium salts (210) were first obtained from the cyclodehydration reaction of l-phenacyl-2(lii)-pyridinone in sulfuric acid (67JHC66). These salts can also be prepared from 2-halo-l-phenacylpyridinium derivatives (211) by treatment with a base which causes ylide formation and hence cyclization by intramolecular substitution (69JOC2129, 76CB3646). It is recommended that a bulky tertiary amine is used as base in order to avoid opening of the ring or substitution of the 2-halo substituent in the starting material (211). Isoquinoline and quinoline analogues have also been prepared by these methods. 

Azine approach. C-l and C-3 in the ring system can be regarded as aminal carbons the ring system is formed accordingly. The perhydro derivative (628) can be formed from acetaldehyde and perhydropyridazine (72JA7108). 

Hydrogenation of hydrazones and azines is a useful way to prepare hydrazine derivatives. The hydrogenation may proceed further to amines depending on the structure of compound, catalyst, and reaction conditions. Unsubstituted hydrazones (I) are liable to hydrolysis, especially with the hydrazones derived from ketones in acidic media and slow hydrogenation. The ketones thus formed may afford azines (II) by condensation with the parent hydrazones. Hydrogenation of azines affords symmetrically... 

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