Triisopropylbenzenesulfonyl tetrazole

Brandt, K. Haas, A. Hardt, X Mayer-Rigge, H. Merz, K. Wallmichrath, X, J. Fluorine Chem. 1999, 97, 115. 

Alternate Name l-(2,4,6-triisopropylbenzenesulfonyl)tetrazole TPS-tetr azole. 

Form Supplied in prepare immediately before use by the reaction of 2,4,6-triisopropylbenzenesulfonyl chloride with tetrazole. 

Handling, Storage, and Precaution all arylsulfonyl tetrazoles decompose on storage in a desiccator, and the most unstable is benzenesulfonyltetrazole which deconposes conpletely in 10 days. It is advisable to prepare triisopropylbenzenesulfonyl tetrazole freshly before use. 

Preparation of l-(2,4,6-Triisopropylbenzenesulfonyl) Tetrazole. To a solution of dioxane (2 ml) containing triethylamine (10.1 mmol) is added, with cooling, triisopropylbenzenesulfonyl chloride (10 mmol) and tetrazole (10 mmol) (eq 1). After 2 h, the precipitate is filtered off, discarded, and the filtrate is evaporated to dryness. The solid residue is dissolved in chloroform (50 ml) and washed with water (2 x 20 ml). The chloroform solution is dried (anhydrous Na2S04) and, after evaporation of the solvent, the residue is crystallized from benzene/ petroleum ether. 

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Trinucleotides are formed by 5 -deprotection of the dinucleotide and subsequent conversion with the monotriazolide in the presence of N-methylimidazole. The fully protected di- and trideoxyribonucleotides of the following nucleotide sequences have been obtained in high yield T-T (82%), C-T (88%), C-C (84%), CM3 (81%), G-T (83%), A-G-T (65%), C-G-T (61%). The yields are similar to those obtained in a reaction involving l-(triisopropylbenzenesulfonyl)tetrazole as coupling agent(see also Section 12.7). 

In ref. [123], 1-triisopropylbenzenesulfonyl- or mesitylenesulfonyl-5-(pyridine-2-yl)-tetrazole (VIII) was successfully used as a coupling agent for the synthesis of protected di- and trinucleotides. In comparison with the sulfonic acid tetrazolides these are able to achieve a stereoselective synthesis of dinucleoside monophosphate aryl esters. 311 1241... 

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