Nitro ozonolysis

Imidazole, 1 -methyl-5-nitro-2-styryl-ozonolysis, 5, 437 Imidazole, l-methyl-2-phenyl- C NMR, 5, 354 Imidazole, l-methyl-4-phenyl- C NMR, 5, 355 Imidazole, 2-methyl-4-phenyl-acylation, 5, 402... 

Alicyclic hydroxamic acids undergo several specific oxidative cleavage reactions which may be of diagnostic or preparative value. In the pyrrolidine series compounds of type 66 have been oxidized with sodium hypobromite or with periodates to give y-nitroso acids (113). Ozonolysis gives the corresponding y-nitro acids. The related cyclic aldonitrone.s are also oxidized by periodate to nitroso acids, presumably via the hydroxamic acids.This periodate fission was used in the complex degradation of J -nitrones derived from aconitine. 

In general, azides are more easily available than rutro compounds by S 2 reacnon of the corresponding halides Thus, the direct conversion of an azide mto a nitro group is useful for the synthesis of nitro compounds Corey and coworkers have reported the easy cc azides to nitro compounds via ozonolysis of phosphine irrunes fEq 2 70 ... 

When the substrate does not contain a reactive carbon-carbon double bond, the ozonolysis procedure appears to provide a convenient and efficient method for the conversion of primary and secondary nitro compounds into carbonyl compounds fEq. 6.7. ... 

CONVERSION OF NITRO TO CARBONYL BY OZONOLYSIS OF NITRONATES 2,5-HEPTANEDIONE... 

Nitro sugars can also be prepared by oxidation of hydroxylamines. This strategy was used in 1999 by Nicolau et al. for the preparation of nitro sugar 9, a component of the natural occurring antibiotic everninomicin,11 that was obtained by ozonolysis of compound 8 followed by sequential treatment of the resulting compound with TFA and triphenylphosphine (Scheme 4). 

Anomeric nitro sugars [35] are most efficiently prepared by ozonolysis of the N-glycosylnitrones obtained by reaction of aromatic aldehydes with the corresponding sugar oximes via the tautomeric N-glycosylhydroxylamines [36]... 

Addition reaction of zinc-copper reagents to nitro olefins is a versatile method for preparing polyfunctional nitroalkanes.20 A direct ozonolysis of the intermediate zinc nitronate furnishes the corresponding ketone (Nef-reaction).20... 

One of these involves ozonolysis of the nitro enolate at low temperature rather than treatment with n... 

Primary and secoiidary nitroalkanes. A new route to nitro compounds involves conversion of azides to phosphine imines by reaction with triphenyl- or tri-n-butylphos-phine at 25—35° followdd by ozonolysis in CHiCE at — 78°. Presumably the initial ozonidc is converted into a nitfoso compound, which is then oxidized to the nitro compound... 

Benzothiadiazole is oxidized by ozone, potassium permanganate,and chromic acid which all lead to the dicarboxylic acid (8). In the ozonolysis the intermediate crystalline ozonide is decomposed to l,2,5-thiadiazole-3,4-dicarboxaldehyde (isolated as the semicarbazone) as well as 8. Permanganate oxidation has been applied to a number of derivatives of 7, among them being the 5-methyl, 4-nitro, and 4,7-dichloro derivatives. In some cases, particularly in the permanganate oxidation of 4-nitro-2,l,3-benzo-thiadiazole, the yield of 8 is much higher than in the oxidation of the unsuhstituted compound (7). 

Oxidation of the substituents usually gives carboxylic acids, or sometimes the aldehydes. Thus, ozonolysis of 1-methyl-5-nitro-2-styrylimidazole gives the corresponding 2-aldehyde (75LA1465). 

The nitro group can be converted into other useful functional groups following conjugate addition. Reduction gives primary amines while hydrolysis reveals ketones. The hydrolysis is known as the Nef reaction and used to be achieved by formation of the nitro-stabilized anion with a base such as sodium hydroxide followed by hydrolysis with sulfuric acid. These conditions are rather unforgiving for many substrates (and products) so milder methods have been developed. One of these involves ozonolysis of the nitro enolate at low temperature rather than treatment with acid. 

---