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)₂C₆H₄ 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.