Full text: Download
An activated synthon for the efficient introduction of a protected tetrazolylmethyl group into nucleophile-bearing compounds is presented. The β-cyanoethyl protecting group allows for very effective deprotection under mild basic conditions. The synthon can be prepared by a two-step procedure (42 %) starting from cheap starting material and can alkylate piperidine in 91 % yield. Even quadruple alkylation to form a protected version of the hexadentate ligand EDTT gives decent yields. Simultaneous removal of the four protecting groups furnishes the lithium salt of a formally zwitterionic ligand in 75 % yield. Finally, the synthon's performance has been assessed by comparison with its benzyl-protected counterpart and was found to be equally efficient in the alkylation of simple amines but superior in deprotection. For substrates bearing basic amine sites, the β-cyanoethyl group is largely preferable.