Trimethylsilyl azide, reaction with aromatic

To avoid the direct manipulation with hazardous azides, methods using Cu(I)situ generation of azides were developed as one-pot procedures, for example, with substitution reaction of alkyl hahdes by NaN3 [493] or with nitrosation of aromatic primary amines by tBuONO followed by trimethylsilyl azide [494]. Vice versa, the alkyne component has been generated in situ, for example, by sequential Seyferth-Gilbert reaction (homologation of aldehydes with diazophosphonates) and reaction with azides in a Cu(l)-catalyzed cycloaddition [495]. 

Takeuchi and coworkers developed a reaction of hydrazoic acid with aromatic compounds in the presence of both trifluoromethanesulphonic acid (TFSA) and trifluoroacetic acid (TFA) giving aromatic amine in good yield [99]. The strong acidity of TFSA and the high solubility of TFSA in TFA play an important role in the aromatic amination. In addition, the combine of trimethylsilyl azide/trific acid, NaN3/trillic acid/aromatics, or HN3/HOTf/TFA was found effective for one-step preparation of primary aromatic amines from aromatics [100-102]. Very recently, Surya Prakash and coworkers developed an electrophilic rritrogenation of aromatics with sodium azide in BF3-H2O [103]. 

The (3-azidation reaction of triisopropylsilyl enol ethers (Schemes 3.186 and 3.187) has been effectively utilized in organic synthesis [563-565]. Magnus and coworkers have developed a mechanistically different enone synthesis that involves treatment of (3-azido TIPS enol ethers 469 and 471 with fluoride anion to effect desilylation and concomitant (3-elimination to give an a,(3-enone [563]. Alternatively, the (3-azido group in 469 or 471 can be ionized with MesAl or Me2AlCl and the intermediate enonium ion trapped by various nucleophiles, such as an allylstannane, electron-rich aromatics and trimethylsilyl enol ethers, to give various (3-substituted TIPS enol ethers. Reduction of the (3-azido TIPS enol ether provides access to the synthetically useful p-amino TIPS enol ethers [563]. 

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