Sulfonyl tetrazoles, synthesis

Demko, Z.P. Sharpless, K.B. A click chemistry approach to tetrazoles by huisgen 1,3-dipolar cycloaddition Synthesis of 5-sulfonyl tetrazoles from azides and sulfonyl cyanides. Angew. Chem. Int. Ed. 2002,... 

The first examples of a direct 1,5-substituents tetrazole synthesis via an intermolecular [2 + 3]-cycloaddition reaction of organic azides (based on the results for a similar synthesis of triazoles) were developed by Sharpless et al. in 2002 using sulfonyl or acyl cyaiudes (Scheme 9.8). In both cases, the Click reaction involved simple heating of the organic azides (hindered, aliphatic or aryl azides) and the nitriles into a homogenous liquid at higher reaction temperature (80-100 °C), in which no further purification was necessary. 

Scheme 9.8 [2 + 3] Dipolar cycloaddition for the synthesis of 1,5-disubstituted sulfonyl tetrazoles (A) and acyl tetrazoles...

A catch and release synthesis of tetrazoles and cyclic amidines has been reported making use of solid-supported oximes [94]. When bound sulpho-nyloximes, obtained by reacting polymer supported sulfonyl chloride with oximes, were reacted with nucleophiles, tetrazoles or cychc amidines were obtained (Scheme 19). Alternatively, the use of TMS-CN affords imino nitriles, which have been used as intermediates for the preparation of indoles, 1,2,3,4-tetrahydropyridines, quinoxalines and benzimidazoles. 

Other methods for the synthesis of l,4-dihydro-l,2,4,5-tetrazines 9 which can be explained by intermediate formation of nitrile imines 8 are the photolysis of 1,2,3-triazoles 2181 and sydnones 3,182 reaction of tetrazoles 4180 with tosyl chloride, elimination of pyridine from the pyridinium compounds 5,189-190 of hydrogen chloride from the hydrazonic acid chlorides 1 s.3-i88 or elimination 0f sulfinate from the a-sulfonyl hydrazone 7.189... 

The concept of silyl enol ether synthesis via / -elimination from a Brook rearrangement-derived carbanion also appeared in Wicha s studies on additions of 1-phenyl-l//-tetrazol-5-yl (PT) sulfonyl anions to acyl silanes. When PT sulfone 34 was deprotonated in the presence of acyl(triphenyl)silane, ketone 36 was isolated in good yield after hydrolysis of the silyl enol ether intermediate 35. The mechanism involved addition of the... 

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