Methyl thermal reaction with azides

Benzodiazepin-2-ones are converted efficiently into the 3-amino derivatives by reaction with triisopropylbenzenesulfonyl (trisyl) azide followed by reduction <96TL6685>. Imines from these amines undergo thermal or lithium catalysed cycloaddition to dipolarophiles to yield 3-spiro-pyrrolidine derivatives <96T13455>. Thus, treatment of the imine 50 (R = naphthyl) with LiBr/DBU in the presence of methyl acrylate affords 51 in high yield. 

Analogous methyl azidoformate forms with norbornene a thermal unstable triazoline.251 The decomposition products are 40% aziridine and 55% imide. Furthermore it has been observed that the rate of nitrogen evolution of the triazoline from methyl azidoformate increases threefold when triglyme and 20-fold when dimethyl sulfoxide are substituted for 1,1-diphenylethane as solvents. This fact supports a betaine intermediate in the thermal decomposition reaction. The triazoline from 2,4-dinitrophenyl azide and norbornene could just be isolated, but from picryl azide only the aziridine was obtained.252-254 Nevertheless, the high negative value of the activation entropy (—33.4 eu) indicates a similar cyclic transition state for both reactions. 

The thermal reaction (130°) of ethyl azidoformate with acetylenes yields, by 1,3-dipolar addition of the nitrene, 2-ethoxyoxazoles. With diphenylacetylene, 4,5-diphenyl-2-ethoxyoxazole (199) was obtained in 45% yield. With methyl propiolate or dimethyl acetylenedicar-boxylate, addition of the azide was faster than the nitrene formation, so triazoles were the major products. In these cases oxazoies were formed only in 3% yield The photochemical reaction of methyl... 

Cinnolines may be formed by the cyclization of 2-hydrazone or 2-hydrazonophosphorane derivatives of 3-(2-fluoro- or chlorophenyl)-3-oxopropionates (Scheme 87), which are prepared from the oxopropionates via reaction with /i-toluenesulfonyl azide and treatment of the diazo derivatives with phosphines. Simple hydrazones undergo cyclization by displacement of fluoride under thermal or basic conditions, and reaction of chloro compounds is successful under basic conditions, though Wolff-Kishner reduction may compete in the absence of a methyl group on the terminal nitrogen. The diazo compounds cyclize, via tri- -butylphosphazines, more readily than do the hydrazones and base catalysis is not required it may be that cyclization proceeds via a phosphonium salt, with subsequent hydration and elimination of tri- -butylphosphine oxide. The triphenylphosphazines do not cyclize, but are labile intermediates to the hydrazones <88Cpbi321>. 

Amino-5-nitro-1,2,3-triazole (ANTZ) (130), an explosive showing high thermal stability, has been synthesized via this route the reaction of sodium azide, acetaldehyde and 2,2-dinitroethyl acetate forming 4-methyl-5-nitro-1,2,3-triazole, which on conversion of the methyl group to an amino group yields ANTZ (130). Treatment of ANTZ (130) with hydrogen peroxide in sulfuric acid yields 4,5-dinitro-1,2,3-triazole (DNTZ) (131). 

These conclusions were anticipated by product studies. Alkyl azides are readily available and their thermal and photochemical decomposition reactions have been studied. In general, light and heat induced decomposition of methyl azide does not produce a MeN species that can be intercepted in respectable yields with a bimolecular trap. For example, attempts to trap MeN with cyclohexane as solvent produced only a 0.4% yield of adduct. Photolysis of CH3N3 or CD3N3 at cryogenic temperatures fails to produce an IR spectrum attributable to triplet methylnitrene. The IR spectrum of CH2=NH (or CD2=ND) is observed instead. " ... 

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