Metal-Free Highly Regioselective 1,4-Sulfonyliodination of 1,3-Enynes

Abstract

Herein, a novel, practical, and green synthetic method using readily available 1,3-enynes with sulfonyl hydrazides and I2 through tert-butyl hydroperoxide (TBHP)-mediated 1,4-sulfonyliodination has been developed for synthesizing various tetrasubstituted allenyl iodides under metal-free conditions. Notably, the proposed method exhibits a broad substrate scope, operational simplicity, tolerance to air, high functional-group tolerance, satisfactory yields, and excellent regioselectivity as well as involves the use of cost-effective reagents such as green oxidants.

Remote Radical 1,3-, 1,4-, 1,5-, 1,6- and 1,7-Difunctionalization Reactions

“…Sulfonyl-containing allenyl nitrile products 17 are obtained after the reductive elimination of the Cu-catalyst. Lv et al, also developed a 1,4-sulfonyliodination reaction of 1,3-enynes to synthesize a tetrasubstituted allenyl iodides 18 under metal-free conditions ( Scheme 19 ) [ 51 ]. The reaction of 1,3-enynes with sulfonyl hydrazides and I 2 in the presence of tert -butyl hydroperoxide (TBHP) at room temperature gave the allenyl iodide products in satisfactory yields with excellent regioselectivity and good functional group tolerance.…”