REGULAR STRUCTURAL PAPERS 1691 2:1, with a disordered solvate molecule at the (x,x,0) position on the twofold axis. The refinement of the disordered ethyl ac- etate molecule gave some trouble; several attempts were made to interpret the confused difference map and to refine the six in- dependent heavy atoms with population factors of 0.5, but there were always very high correlations between various parameters and an unacceptable molecular geometry. The best interpreta- tion was to place the bridge O atom O 1S on the twofold axis and to consider the C atoms of the acetyl and ethyl groups to be equivalent; in this interpretation, the carboxyl O atom O2S is the only atom with a population factor of 0.5. At the end of the refinement, the geometry of the group was quite acceptable but nevertheless, we considered the inclusion of the H atoms of the ethyl acetate molecule in the model to be of little significance. Data collection and cell refinement: Enraf-Nonlus software. Data reduction and structure refinement: SDP-PIus (Frenz, 1983). Structure solution: MULTANll/82 (Main, Fiske, Hull, Lessinger, Germain, Declercq & Woolfson, 1982). Software used to prepare material for publication: PARST(Nardelli, 1983) and ORTEPII (Johnson, 1976). We thank the Servizio Italiano di Diffusione Dati Cristallografici del CNR (Parma) for access to the Cam- bridge Data Files. Acta Cryst. (1993). CA9, 1691-1693 Structure of ( __ )-Tetrahydropalmatine BI~LA RIB~,R* Serbian Academy of Sciences and Arts - Branch in Novi Sad, 21000 Novi Sad, Ul. Svetozara Markovida 4, Serbia DU~AN LAZAR, OLGA GA~IC AND IsTVAN KANYO Institute of Physics and Institute of Chemistry, Faculty of Sciences, 21000 Novi Sad, Trg Dositeja Obradovi(a 4, Serbia YURY ALEXANDROVICH SIMONOV AND VICTOR CHRISTOFOROVICH KRAVTSOV Institute of Applied Physics, Academy of Sciences, Kishinev, 277028 Akademicheskaya 5, Moldavia (Received 18 November 1992; accepted 5 March 1993) Lists of structure factors, anisotropicthermal parameters, H-atom coor- dinates and completegeometryhave been deposited with the BritishLi- brary Document Supply Centre as Supplementary PublicationNo. SUP 71227 (36 pp.). Copies may be obtained through The TechnicalEditor, International Union of Crystallography,5 Abbey Square, Chester CH 1 2HU, England. [CIF reference: NA 1036] References Aimi, N., Asada., Y., Sakai, S. I. & Haginiwa,J. (1978). Chem. Pharm. Bull. 26, 1182-1187. Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-S19. Bui, A. M., Das, B. & Potier, R. (1980). Phytochemistry, 19, 1473-1475. Chiaroni, A., Riche, C., Diatta, L., Andriamialisoa, R. Z., Langlois,N. & Potier, P. (1976). Tetrahedron, 32, 1899-1902. Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358. Frenz, B. A. (1983). Enraf-Nonius Structure Determination Package; SDP User's Guide. Versionof 6 January 1983. Enraf-Nonius,Delft, The Netherlands. Henriques, A., Kan, C., Chiaroni, A., Riche, C., Husson, H.-P., Kan, S.-K. & Lounasmaa, M. (1982). J. Org. Chem. 47, 803-811. Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge Na- tional Laboratory, Tennessee, USA. Lefebvre-Soubeyran,O. (1973). Acta Cryst. B29, 2855-2863. Main, P., Fiske, S. J., Hull, S. E., Lessinger,L., Germain,G., Declercq, J.-P. & Woolfson,M. M. (1982). MULTANll[82. A System of Com- puter Programs for the Automatic Solution of Crystal Structures from X-ray Diffraction Data. Univs. of York, England, and Louvain, Bel- gium. Nardelli, M. (1983). Comput. Chem. 7, 95-98. Plat, M., Le Men, J., Janot, M. M., Budzikiewicz,H., Wilson, J. M., Durham, L. J. & Djerassi, C. (1962). Bull. Soc. Chim. Fr. pp. 2237- 2241. Saxton, J. E. (1983). The AspidospermineGroup.Indoles. The Monoter- penoid Indole Alkaloids, pp. 331-437. New York: Wiley. Stout, G. H. & Jensen, L. H. (1968). X-ray Structure Determination, p. 411. London: Macmillan. © 1993 International Union of Crystallography Printed in Great Britain - all rights reserved Abstract In 5,8,13,13a-tetrahydro-2,3,9,10-tetramethoxy-6H- dibenzo[a,g]quinolizine, according to the puckering parameters [Cremer & Pople (1975). J. Am. Chem. Soc. 97, 1354-1558] the trans fused ring B [Q = 0.518 (5)/~, ~o = 145.4 (7) °, 0 = 51.6 (6) °] and ring C [Q = 0.529 (4) ]~, ~0 = 328.2 (5) °, 0 = 48.2 (4) °] of the quinolizine moiety both have almost perfect half- chair conformations. The mean value of the three C--N--C angles is 110.0 (3) ° indicating sp 3 hybridi- zation of the N atom. Molecules are held together by van der Waals interactions. Comment Tetrahydropalmatine is a tetrahydroprotoberberine alkaloid previously isolated from Corydalis aurea, C. lutea and C. ochroleuca (Glasby, 1975). We have isolated the same alkaloid from the roots of C. cava, as well as from the overground parts and roots of C. solida collected at the Frugka Gora mountain (Vojvodina). Isolation was performed as described by Gagi6, Popovid & Dragutinovi6 (1985). The dihedral angle between the phenyl rings A and D is 25.8 (1) ° as compared to 33.8 (1) ° in isocorypalmine (Ribfir, Radivojevi6, Ga~i6, Kany6 & Goli6, 1992) and 36.7(1)° in corydaline (Ribfir, Lazar, Radivojevi~, Engel, Gagi~ & Kany6, 1992). The O3--C19 bond is perpendicular to the plane of phenyl ring D, while the O4--C20 bond is in the plane of the same ring. The O1--C21 and O2--C18 bonds are in the plane of phenyl ring A, as indicated Acta Crystallographica Section C ISSN 0108-2701 ©1993