Reactions of organotin tetrazoles: synthesis of functionalised poly-tetrazoles

Reaction of 1,2-bis[2-(tributylstannyl)tetrazol-5-yl]benzene with 1,2-dibromoethane (1:10) yields the 1- N,1-N'-ethylene bridged cyclophane (1) while similar reactions with larger excesses (1:25) of 1,n- dibromoalkanes yield 1,2-bis[2-(bromoalkyl)tetrazol-5-yl]benzenes along with the unsymmetrical 1-N,2- N-substituted tetrazole isomers. Analogous products from 1,3-(Bu3SnN4C)(2)C6H4 are also reported. Similar reactions occur between the two organotin compounds and 1-bromo-n-cyanoalkanes to give 1,m-bis[(cyanoalkyl)tetrazol-5 yl]benzenes (m = 2, 3) as both symmetric and unsymmetrically substituted tetrazole isomers, and which can be further developed to convert the pendant nitriles into tetrazoles by cycloaddition reactions with Bu3SnN3. The Bu3Sn group is easily cleaved by H+ to generate the related N-unsubstituted tetrazoles.