Imidazo[4',5':4,5]cyclopenta[1,2-e]pyrrolo[1,2-a]pyrazine-4,7-dione,1,2-dibromo-5,5a,5b,6,8,8a,9,9a-octahydro-8a-hydroxy-8-methyl-, [5aS-(5aa,5bb,8ab,9aa)]-