1.3- Oxazines 5-nitro-tetrahydro

It has been found that the simplest method of preparing 5-nitro-tetrahydro-l,3-oxazine derivatives consists in warming 2-alkyl-2-nitropropane-l,3-diol with formaldehyde and ammonia or primary amines ... 

A number of diastereoisomeric pairs of quaternary salts of 5-nitro-tetrahydro-l,3-oxazine derivatives (11a and lib) were prepared by the action of n-alkyl bromides or iodides on 5-nitrotetrahydro-1,3-oxazines.61 The products contained at the 3-equatorial position the n-alkyl derived from the alkyl bromide (or iodide), 6a and 6b [Eqs. (4) and (5)]. 

Investigations of the conformational analysis of 5-alkyl-5-nitro-tetrahydro-l,3-oxazines by dipole moments1 have been extended to derivatives with various substituents in positions 3 and 5.281-282 They... 

Oxazin 5-(4-Chlor-benzyl)-2-ethyl-5-nitro-tetrahydro- E14a/2, 711 (l,3-Diol/CH20/R-NH2)... 

H-1,2-Oxazine, 3,6-dihydro-6-(2-pyridyl)-mass spectra, 2, 529 2H-1,2-Oxazine, tetrahydro-synthesis, 2, 92 4H-l,2-Oxazine, 5,6-dihydro-pyrolysis, 3, 999 synthesis, 3, 1017 tautomerism, 3, 999 4H-1,2-Oxazine, 5,6-dihydro-3-methyl-metallation, 1, 484 4H-l,2-Oxazine, 5,6-dihydro-3-nitro-reactions, 3, 1000 6H-l,2-Oxazine, 3,5-diphenyl-stability, 3, 997 synthesis, 3, 1014... 

One of the most extensively investigated groups of 1,3-oxazine derivatives is the 5-nitro derivatives of tetrahydro-l,3-oxazine. They were first prepared from 1-nitropropane, aqueous formaldehyde, and ammonia by Hirst et and independently by Senkus from other primary nitroparaffins, formaldehyde, and primary amines. Numerous compounds of the general formula (6) were later prepared from primary nitroparaffins. " ... 

A compound formerly reported53 with an eight-membered oxazocine ring proved to contain a 2-nitrotetrahydro-l,3-oxazine ring, being a diastereoisomer of 5-ethyl-5-nitro-3-(2-nitrobutyl)tetrahydro-l, 3-oxa-zine.1-37,47... 

As indicated previously,1 ring opening occurs readily with tetra-hydro-l,3-oxazines. This property was recently reviewed,37 and the review includes a description of the formation of 3-amino-2-nitro-propanol and of 2-amino-l-nitro compounds, hydrolysis and degradation products, respectively, of the tetrahydro-l,3-oxazines. 

Eliel et a/.268 seem to confirm the observation that the nitro group in this type of heterocyclic system is preferred in the axial position. Katritzky et a/.269-271 have found on the basis of dipole moment measurements that tetrahydro-l,3-oxazines without a 5-nitro group have V-alkyl in the preferred equatorial position, although the axial N-CH3 and -C2H5 are important minor contributors (42 and 32%, respectively). 

Tetrahydro-l,3-oxazin 3-Ethyl-5-(l-methy 1-1 -nitro-ethyl)-5-nitro-E14a/2. 712 [C = NO -> C(N02)-C]... 

Oxazin 5.5-Dimethyl-2-(5-nitro-2-furyl)-3-nitroso-tetrahydro-EI4a/2, 718 (HO — C — C —C— NH2/R — CHO/HN02)... 

Oxazin 3-Ethyl-5-(4-nitro-benzylidenj-tetrahydro- F.14a/2, 712 (C=NOf -v C = C) Propansaure 2-(3-Acetyl-phenylhyd-razono)- -ethylester E6b/1, 740 (Ar-Nf + H3C-CO-COOR) Qninazolin 6,7-Dimethoxy-2-hydroxy-4-isopropyl- E9b/2, 59 [3,4-(OR)2 -Ar-NH-CO-NH-CO-R/A]... 

Dioxo-3-ethyl-l, 5,6,7-tetrahydro- 677 Pyrazolo[3,4-d]-l, 3-oxazin l,3-Dimethyl-4-oxo-6-(2-oxo-propyl)-dihydro- 557 1- Acyl-3-methylthio-6-oxo-l,6-dihydro- 676 2- Benzyl-6-(4-nitro-phenyl)-4-oxo-2,4-dihydro-676 4-Amino-7-chlor-phenyl- 976 2-(4-Aminosulfonyl-phenyl)-4,7-dichIor- 977 2-(4-Aminosulfonyl-phcnyl)-4,7-dihydroxy- 922 4-Anilino-7-chlor-2-(3-thienyl)- aus 4,7-DichIor-2-(3-thicnyI)- pyriclazino-[4,5-d]-l,3-thia7.ol)/Ethanol 976 7-Chlor-4-ethoxy-2-methyl- 972 7-Chlor-4-methoxy-2-phenyl- 972 7-ChIor-4-(3-pyrroIidino-propyloxy)-2-(2-thienyI)- 972... 

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