Benzofuroxan (1) reacts with phosphorus ylide 2 to give benzimidazole derivatives 8 and 10, Whereas reaction of 1 with ylide 12 furnishes quinoxaline 17 via an Initial Wittig-type reaction. Similarly the reaction between the furoxano [3.4-b] quinoxalines 19a or 19b and the ylide 2 yielded compounds 22a and 22b, respectively. In these reactions as well as in the reactions of the above furoxans with other phosphorus ylides, a significant ...