Synthesis of 1,5-diisopropyl substituted 6-oxoverdazyls

Abstract

1,5-Diisopropyl-6-oxo-verdazyl free radicals were synthesized via the condensation of BOC protected isopropyl hydrazine with phosgene, deprotection with aqueous HCl, condensation with aldehydes to form tetrazanes and finally oxidation to give the free radicals. The introduction of isopropyl groups results in free radicals that show greater solubility in a variety of solvents and are more stable than their methyl substituted counterparts. ESR shows reduced hyperfine coupling to the isopropyl methine hydrogens consistent with this hydrogen being in the plane of the verdazyl ring.