Dioximes as synthons for medium ring heterocyclic compounds

A simple and convenient synthetic approach to eight-, nine- and ten-membere d nitrogen and oxygen containing heterocycles has been developed. 3,4-Diary l-1,6,2,5 -dioxadiazocines, (3) and (4), 3,4-diaryl-1,6,2,5 -dioxadiazonine s,(5) and 3,4-diaryl-1,6,2,5-dioxadiazacyclodeca-2,4-dienes (6) are prepare d in one-pot from vicinal dioximes (1) via dianion intermediate(2) and 1,2- dibromoethylene, 1,2-dichloroethane, 1,3-dibromopropane and 1,4-dichlorobut ane, respectively. A plausible mechanism has been discussed.