Aryl azides, reactions produce

Organoboranes react with a mixture of aqueous NH3 and NaOCl to produce primary amines. It is likely that the actual reagent is chloramine NH2CI. Chloramine itself,hydroxylamine-O-sulfonic acid in diglyme, and trimethyl-silyl azide " also give the reaction. Since the boranes can be prepared by the hydroboration of alkenes (15-16), this is an indirect method for the addition of NH3 to a double bond with anti-Markovnikov orientation. Secondary amines can be prepared by the treatment of alkyl- or aryldichloroboranes or dialkylchlorobor-anes with alkyl or aryl azides. 

Chang et al. reported a mild tandem intramolecular hydroamination of yne amines to form an endo-adduct intermediate, which reacts with electron-deficient azides to produce cyclic amidines <06JA12366>. Selected examples of an interesting synthetic route to tropene derivatives 165 via a dual hydroamination strategy is shown below. This one-step reaction makes use of a palladium catalyst and takes place by sequential intermolecular hydroamination of cycloheptatriene with aryl, heteroaryl, and primary alkyl amines to generate intermediate 166, followed by transannular intramolecular hydroamination <06JA8134>. 

Arylamines and hydrazines react with tosyl azide under basic conditions to yield aryl azides [1] and arenes [2], respectively, by an aza-transfer process (Scheme 5.25). Traditionally, the reaction of anilines with tosyl azides requires strong bases, such as alkyl lithiums, but acceptable yields (>50%) have been obtained under liquidiliquid phase-transfer catalytic conditions. Not surprisingly, the best yields are obtained when the aryl ring is substituted by an electron-withdrawing substituent, and the yields for the corresponding reaction with aliphatic amines are generally poor (-20%). Comparison of the catalytic effect of various quaternary ammonium salts showed that tetra-/i-butylammonium bromide produces the best conversion, but differences between the various catalysts were minimal [ 1 ]. 

Substituted anhydro-5-hydroxy-l,2,3,4-oxatriazolium hydroxides (4) decompose on heating in strong acids <320912,56JA5124>. The 3-alkyl substituted compounds produce carbon dioxide, azo-imide (HN3), and the alcohol corresponding to the 3-substituent. The 3-aryl substituted analogues produce carbon dioxide and aryl azide. In some cases the initially formed aryl azide decomposes further to anilines under the conditions of the reaction <82JCS(P2)70l>. Kinetic studies indicate that 3-methyl-anhydro-5-hydroxy-l,2,3,4-oxatriazolium hydroxide (24) reacts via a bimolecular A-2... 

An alternative approach to N-S bond formation involves the aza-Wittig-type reaction of sulfoxides (Scheme 26) <2004SL101>. Initial Staudinger ligation of aryl azide 195 with triphenylphosphine afforded iminophosphorane 196, which was purified by column chromatography and then heated in anhydrous toluene, producing benzothiazines 62 and 197. The N-S bond was found to be rather sensitive to hydrolysis and cleavage to 198 was observed upon treatment of benzothiazines 62 or 197 with wet THF. 

Laser flash photolysis of a series of fluorinated aryl azides produces the transient spectra of the corresponding singlet nitrenes. ° With the exception of singlet o-fiuorophenylnitrene (39s), the rate of decay of the singlet nitrene was equal to the rate of formation of the reaction products, for example, didehydroazepines and triplet nitrenes. Values of fejsc and the Arrhenius parameters for azirine formation are summarized in Table 11.5. 

The photochemistry of aryl azides is quite complex, suggesting that the nitrene 14 may not be the only reactive intermediate and that insertion reactions may not be the only route to form photoconjugates.Although aryl nitrenes are much less susceptible to rearrangements than acyl nitrenes, they may still occur and lead to the formation of reactive intermediates such as azepines, which may go on to react with nucleophiles.[911 141 Addition of nitrenes to double bonds will generate azirines, while dimerization will produce azobenzenesJ11 Aryl azides are stable to most of the procedures used in the course of peptide synthesis except for reduction reactions. Non-photochemical reduction of aryl azides to the primary amines by thiols has been reported by Staros et al.[15]... 

Some recent examples of the use of this cycloaddition include reaction of aryl azides with (i) enamine 271 to give diaminodihydrotriazol 272, which on deamination produces... 

The development of the chemistry of aryl nitrenes has occurred primarily over the last 20 years, even though initial forays were made nearly a century ago. This slow development can be attributed to the fact that photolysis or pyrolysis of typical aryl azides, such as phenylnitrene 1, produces polymeric tar (Reaction 5.1). This is in sharp contrast to the rich chemistry of phenylcarbene (2), which exhibits insertion into C-H bonds, addition to Jt-bonds, reaction with oxygen, and so on. ... 

The photolysis of aryl azides in low-temperature matrices yields triplet (ground) state nitrenes which have been identified by and absorption spectroscopy. Dinitrenes and trinitrenes have also been reported in the solid-state photolysis of di- and triazides. Quantum yields of photolysis of some aromatic azides are listed in Table 21 and it appears that nitrenes are produced in solution, at room temperature, as well. The lifetimes of some aromatic nitrenes and the absolute rates of some of their reactions have been measured . Some interesting features of photolytic azide decompositions will now be briefly described. 

Chemiluminescence has been used to measure the relative yields of excited ketones formed from self reaction of alkoxyl and alkylperoxyl radical pairs . In the photochemistry of aryl azides a dehydroazepine is detected by time resolved infra red spectroscopy and flash photolysis at room temperature . Singlet and triplet nitrenes and dehydroazepenes have also been detected in the photochemistry of 3- and 4-nitrophenyl azides . Picosecond and nanosecond laser photolysis of p-nitrophenyl acetate in aqueous media produces a triplet state of the -nitrobenzylanion and CO2 after cleavage of the rnr triplet. Absorption, emission, and reaction kinetics of dimethylsilylene produced by flash photolyses of dodecamethylcycloherasilane is another interesting study 2,... 

It should be noted that prolonged heating of aryl azides with sodium ethoxide alone also produces triazoles. The reaction requires two... 

Bis(aryl)azide rubber resist is a common negative photoresist. In a photoreaction, the evolution of nitrogen from the acylazide produces a highly reactive intermediate, nitrene. Through a series of reactions the nitrene intermediate leads to the formation of polymer by cross-linking the resin. The unreacted negative photoresist can then be dissolved in organic solvent, and xylene is commonly used. 

The reactions of nitrenes produced in the photoelimination reactions of aryl azides. 

Scheme 29 A Reaction of alkyl azides 130 with aryl isocyanates 131 to yield 1-alkyl-4-aryl-A -tetrazoline-5-ones 132 B Reaction of alkyl azides 133 with acyl isocyanates or carboalkoxy isocyanates 134 to l-alkyl-4-acyl-A -tetrazoline-5-ones and l-alkyl-4-carboalkoxy-A -tetrazoline-5-ones 135 (C). Reaction of aryl azides and alkyl azides 137 with sulfonyl isocyanates 138 to produce l-aryl-4-sulfonyl-A -tetrazoline-5-ones and l-alkyl-4-sulfonyl-A -tetrazoline-5-ones 139 [107]...

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