2-(5,6,8,9,11,12-Hexahydro-7,10-dioxa-1,3,4,13-tetrathia-cyclopentacyclododecen-2-ylidene)-5,6,8,9,11,12-hexahydro-7,10-dioxa-1,3,4,13-tetrathia-cyclopentacyclododecene AIDS-138058 AIDS138058 NSC644014