2,4-Dinitrobenzenesulphenylnitrene: addition to (Z)- and (E)-1-phenylpropene

Abstract

Oxidation of 2,4-dinitrobenzenesulphenamide (1) with lead tetra-acetate in the presence of (Z)-1-phenylpropene gives a ca. 3:1 mixture of cis- and trans-aziridines (3) and (4), respectively. This ratio is unchanged over a tenfold decrease in concentration of (Z)-1-phenylpropene. The ratio of compounds (3) : (4) is unaffected by carrying out the oxidation in the presence of 1,1-diphenylethene, 2-phenylpropene or oxygen (triplet traps), although both the last-named alkenes react preferentially with the intermediate(s) generated in the reaction. The ratio (3) : (4)is affected by carrying out the oxidation in the presence of an allyl aryl sulphide, a particularly effective singlet nitrene trap. It is concluded that at least two intermediates are involved in the addition to (Z)-1-phenylpropene, one of which is a singlet nitrene; however the other is not the triplet nitrene.

Partial isomerisation of the (Z)-1-phenylpropene to (E)-1-phenylpropene in these reactions is attributed to the reversible addition of the 2,4-dinitrobenzenesulphenamidyl radical, 2,4-(NO₂)₂PhSṄH to the (Z)-alkene