title: Diethyl 7,8-dibromo-4,11-dioxo-11b,11c-dihydro-5H,10H-2-oxa-3a,4a,10a,11a-tetra-azabenz[f]indeno[2,1,7,7a-ija]azulene-11b,11c-dicarboxyl-ate.
abstract: The title compound, C(20)H(20)Br(2)N(4)O(7), is an inter-mediate for mol-ecular clips. The seven- and six-membered rings have chair conformations, while the five-membered rings adopt envelope conformations. In the crystal structure, weak C-H⋯O and C-H⋯Br inter-actions link the mol-ecules into a three-dimensional network. The eth-oxy and ethyl groups are disordered over two orientations, with occupancy ratios of 0.735 (16):0.265 (16) and 0.51 (2):0.49 (2), respectively.
authors.affiliation: Key Laboratory of Pesticides and Chemical Biology of the Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Nengfang
authors.initials: N
authors.lastname: She