J. ANTEL, G. M. SHELDRICK, T. PFEIFFER AND L.-F. TIETZE 2227 Table 2. Bond lengths (,t~) and bond angles (o) O(6)-C(5a) 1.343 (2) O(6)-C(7) 1.456 (2) C(5a)-O(5) 1.336 (2) C(5a)-C(10b) 1.355 (2) O(5)-C(4) 1.424 (2) N(2)--C(1) 1.352 (2) N(2)-C(2n) 1.45J (2) N(2)-C(3) 1.460 (2) O(I)--C(I) 1.234 (2) C(I)-C(10b) 1.491 (2) C(10b)-C(10a) 1.532 (2) C(4)-C(lp) 1.515 (2) C(4)-C(3) 1.516 (2) C(lp)-C(2p) 1.378 (3) C(Ip)-C(6p) 1.379 (3) C(10a)-C(7a) 1.541 (3) C(10a)-C(10) 1.542 (3) C(7)-C(7") 1.513 (3) C(7)-C(7a) 1.515 (3) C(7)-C(7') 1.509 (4) C(3)-C(3') 1.526 (3) C(2p)-C(3p) 1.379 (3) C(6p)-C(Sp) 1.400 (3) C(7a)-C(8) 1.530 (4) C(3p)-C(4p) 1.374 (3) C(5p)-C(4p) 1.359 (3) C(10)-C(9a) 1.477 (5) C(8)-C(9a) 1.491 (6) C(7)-O(6)-C(5a) 117.7 (1) O(5)-C(5a)-O(6) 105.2 (1) C(10b)-C(5a)-O(6) 124.2 (2) C(10b)-C(5a)-O(5) 130.6 (2) C(4)-O(5)-C(5a) 118.8 (1) C(2n)--N(2)-C(1) 117.3 (1) C(3)-N(2)-C(1) 126.4 (I) C(3)-N(2)-C(2n) 115.7 (1) O(l)-C(l)--N(2) 119.0 (2) C(10b)--C(1)-N(2) 123.8 (1) C(10b)-C(1)-O(1) 117. l (2) C(1)-C(10b)-C(5a) 129.6 (1) C(lOa)-C(lOb)-C(5a) 118.4 (2) C(10a)-C(10b)-C(1) l 11.9 (1) C(1p)-C(4)-O(5) 107.9 (I) C(3)-C(4)--O(5) Ill.6 (2) C(3)-C(4)-C(lp) 111.0 (l) C(2p)-C(lp)--C(4) 118.5 (2) C(6p)-C(Ip)-C(4) 122.1 (2) C(6p)-C(lp)-C(2p) 119.2 (2) C(7a)-C(lOa)-C(lOb) 113.5 (I) C(10)-C(10a)-C(10b) 112.7 (2) C(lO)-C(lOa)-C(7a) 103.9 (2) C(7")-C(7)-O(6) 103.9 (2) C(7a)-C(7)-O(6) 107.2 (2) C(7a)-C(7)-C(7") 113.6 (2) C(7')-C(7)-O(6) 108.9 (2) C(7')--C(7)-C(7") 110.5 (2) C(7')-C(7)-C(7a) 112.2 (2) C(4)-C(3)-N(2) 112.3 (l) C(3')--C(3)--N(2) 111.8 (2) C(3')-C(3)-C(4) 113. l (2) C(3p)-C(2p)-C(lp) 120.6 (2) C(Sp)-C(6p)-C(lp) 119.5 (2) C(7)-C(7a)-C(lOa) 112.8 (2) C(8)-C(7a)-C(10a) 104.5 (2) C(8)-C(7a)-C(7) 116.1 (2) C(4p)-C(3p)-C(2p) 120.3 (2) C(4p)-C(5p)-C(6p) 120.7 (2) C(Sp)-C(4p)-C(3p) 119.6 (2) C(9a)-C(10)-C(10a) 107.3(2) C(9a)-C(8)--C(7a) I02.3 (3) C(8)-C(9a)-C(10) 106.6 (3) Related literature. For the preparation of the com- pound see Pfeiffer (1988). For the preparation of some related compounds see Tietze, Brand, Pfeiffer, Antel, Harms & Sheldrick (1987). Fig. 1. The molecular structure showing atom-numbering scheme. We thank the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie for financial support. Referenees CLEGG, W. (1981). Acta Cryst. A37, 22-28. International Tablesfor X-ray Crystallography (1974). Vol. IV. Birmingham: Kynoch Press. (Present distributor Kluwer Academic Publishers, Dordrecht.) PFEIFFER, T. (1988). PhD thesis. Univ. of G6ttingen, Federal Republic of Germany. SrmLDRICK, G. M. (1976). SHELX76. Crystal structure refinement program modified by GMS. Univ. of Cambridge, England. SHELDRICK, G. M. (1985). SHELXS86. In Crystallographic Computing 3, edited by G. M. SHELDRICK, C. KROGER & R. GODDAm), pp. 175--189. Oxford Univ. Press. TIETZE, L.-F., BRAND, S., PFEIFFER, T., ANTEL, J., HARMS, K. & SHELDPaCK,G. M. (1987).J.Am. Chem. Soc. 109, 921. Acta Cryst. (1988). C44, 2227-2229 Structure of a Furo[3,4-b]azepine Derivative BY JOCHEN ANTEL AND GEORGE M. SHELDRICK Institut fiir Anorganische Chemic der Universitiit, Tammannstrasse 4, D-3400 G6ttingen, Federal Republic of Germ any AND MATTHIAS BRATZ AND LUTZ-F. TIETZE Institut ffir Organische Chemie der Universit?it, Tammannstrasse 2, D-3400 G6ttingen, Federal Republic of Germany (Received 26 April 1988; accepted 15 July 1988) Abstract. (5aRS,8aRS)-Ethyl 6,6-dimethyl-8-oxo-per- hydrofuro[3,4-b]azepine-8a-carboxylate, C 13H2~NO4, Mr=255.16, monoclinic, P2l/C, a= 7.189 (1), b= 15.057 (2), c= 13.101 (2)/~,, fl= 96.62 (3) ° , V= 1408.65 ./k3, Z = 4, D x = 1.204 Mg m -3, 2(Mo K~t) =0.71069A, p=0.08mm -~, F(000)=552, T= 0108-2701/88/122227-03503.00 © 1988 International Union of Crystallography