Metal-free oxidative [2+2+1] heteroannulation of 1,7-enynes with thiocyanates toward thieno[3,4-]quinolin-4(5)-ones

A new metal-free oxidative [2+2+1] heteroannulation of 1,7-enynes with thiocyanates for producing thieno[3,4- c ]quinolin-4(5 H )-ones is presented. This reaction employs benzoylperoxide (BPO) as the oxidant and sodium thiocyanate as the sulfur source to enable the formation of three chemical bonds, two C-S bonds and one C-C bond, in a single reaction, and represents a new, practical access to S-heterocycles with the avoidance of the use of metal catalysts and excess bases. Transition-metal- and base-free oxidative [2+2+1] heteroannulation of 1,7-enynes with NaSCN as the sulphur source is developed.