Alkyl aluminum azide

On decomposition of the 1 1 adduct of phenyl azide with both alkyl aluminum chlorides, the main reaction is A-ethylation with the formation of IV-ethylanilides 100). 

In 1956, Hattori and co-workers estabUshed that aluminum azide adds to alkyl isocyanates or acid chlorides in tetrahydrofuran to afford l-aUcyl-A -tetrazoline-5-ones in excellent yields [ 101 ]. Three years later, Horwitz and coworkers reported on the synthesis of l-aryl-A -tetrazoline-5-ones by reaction of aryl isocyanates with a mixture of sodium azide and aluminum chloride in tetrahydrofiuan at reflux temperature [102]. The in situ produced aluminum azide adds to the N=C-bond of the corresponding isocyanate 122 and yields the 1-substituted A -tetrazoHne-5-one 124. According to this method, different 1-substituted A -tetrazoUne-5-ones 124 were synthesized by reaction of phenyl isocyanate and further 1-p-substituted phenyl isocyanates with aluminum azide. In addition, acyl halides 123, like acetyl chloride and benzoyl chloride, were converted to 1-methyl and 1-phenyl-A -tetrazoline-5-one with aluminum azide under the same conditions (Scheme 28A). It is assumed that in the initial step of the reaction, aluminum azide is able to coordinate to the aryl isocyanate by foiu pathways, forming an aluminum salt 129. The first two possibilities (Scheme 28B 125 and 126) require the separation of an azide ion from the complex, recombination at the electrophihc carbon atom followed... 

Alkylation of Azide Ion and Reduction A much better method for preparing a primary amine from an alkyl halide is first to convert the alkyl halide to an alkyl azide (R — N3) by a nucleophilic substitution reaction, then reduce the azide to a primary amine with lithium aluminum hydride. 

Alkyl and aryl isocyanates react with aluminum azide, generated in situ from sodium azide, to give 1-substituted 5-hydroxy-l//-tetrazoles 442" ". Better yields are obtained... 

Alkyl azides prepared by nucleophilic substitution of alkyl halides by sodium azide as shown m the first entry of Table 22 3 are reduced to alkylammes by a variety of reagents including lithium aluminum hydride... 

Alkyl azides prepared by nucleophilic substitution by azide ion in primary or secondary alkyl halides are reduced to primary alkylamines by lithium aluminum hydride or by catalytic hydrogenation... 

Whereas aryl, acyl, and sulfonyl azides decompose in the presence of aluminum trichloride in benzene solution only with evolution of N , alkyl azides also split oif significant amounts of N,-.1 -18 At 50° alkylbenzenes and azomethines are obtained. In order to explain these results, Kreher and Jager suggested that two intermediate complexes may be formed (Scheme IV). According to Goubeau, Allenstein, and... 

Several authors have studied the reaction products in the Lewis acid catalyzed decomposition of phenyl and alkyl azides.179-185 Hoegerlee and Butler have found that phenyl azide forms a hydrocarbon-soluble complex at —70° with triethylaluminum, diethylchloroaluminum, and ethyldichloro-aluminum. 1 Upon warming to room temperature, this complex slowly decomposes into an intermediate phenylimine-aluminum compound (25) which then rearranges into a variety of amidoalkylaluminum reaction products (RP) (eq 4). 

Kreher and Jager have studied the aluminum chloride catalyzed decomposition of azidoformates in several solvents.18118 They reasonably assumed that the decomposition process in n-hexane and nitromethane solution proceeds by C02 elimination and the formation of alkyl azides which then decompose into imines (eq 5). Furthermore, infrared analysis has shown that the catalyst is fixed at the carbonyl group of the azido-formate. 

This reaction may involve stepwise addition of the two equivalents of PhNCS via a 3-membered ring intermediate, RN—S—C=NPh.66 A thia-ziridine was also suggested by Borsche67 to explain the formation of 4-phenyl-5-phenylimino-l,2,4-dithiazolidine-3-thione from the aluminum chloride-catalyzed decomposition of phenyl azide in carbon disulfide. If a 4-substituted thiatriazoline is formed from phenyl isothiocyanate and the alkyl azide, the reaction may then be formulated as indicated in Eq. (21). This scheme is supported by the recent findings of Neidlein and... 

The use of acyl azides in the preparation of amines by the Curtius rearrangement has been discussed previously (Section 23-12E). Alkyl azides can be reduced readily by lithium aluminum hydride to amines and, if a pure primary amine is desired, the sequence halide — azide — amine may give as good or better results than does the Gabriel synthesis (Section 23-9D). 

The chemistry of alkyl and alkenyl azides has been well summarized in several recent reviews.233-237 The azides can be prepared via numerous methods, of which the addition of hydrazoic acid to C—C multiple bonds is one. With the exception of cyclopropenes,238 most alkenes are unreactive towards hydrazoic acid itself. However, the addition can be catalyzed by acids (phosphoric acid,239 sulfuric acid260 or trifluoroacetic acid261) or Lewis acids (aluminum trichloride, boron trifluoride or titanium tetrachloride).262... 

The reaction of ferrocenylazide and dimethyl e o-cis-3,6-endoxo-A 4-tetrahydrophthalate gives the ferrocenyl compound 68.70 Reaction of cyanoferrocene with trimethylsilyl azide and aluminum chloride gave ferrocenyltetrazole (69) as the sole organometallic product.71 Alkylation of 69 with methyl iodide affords two A-methyl derivatives. The major product is assigned the structure 2-methyl-5-ferrocenyl-tetrazole, while the minor product is assumed to be the 1-methyl isomer. 

Formation and Reduction of Nitriles Like the azide ion, cyanide ion (- C=N ) is a good Sn2 nucleophile it displaces leaving groups from unhindered primary and secondary alkyl halides and tosylates. The product is a nitrile (R—C=N), which has no tendency to react further. Nitriles are reduced to primary amines by lithium aluminum hydride or by catalytic hydrogenation. 

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