The Crystal Structure of the Complex [Y(H20)s(N03)2] [Y(H20)2(N03)4]

The title compound was prepared by thermal d\u27ecomposition of crystals of Y (H20)4(N03)s · 2H20. The structure was solved by. Patterson and Fourier methods and isotropically refined to R=0.12. The unit cell is orthorhombic; the space group is C2221 The crystal contains two crystallographically and chemically different complex ions, with yttrium atoms as the center of the complexes. The coordination number of the ion Y (H20h(N08)4 is 10, while the ion Y (H20)5(N03)2 has coordination number 9

Crystal and Molecular Structure of Chelidonine

The crystal and molecular structure of benzophenantridine alkaloid chelidonine, C20H19N05 CM = 353.37) was solved by direct methods and refined by the least-squares technique to a conventional R index of 0.117 for 1888 unique reflections. The crystals are monoclinic, space group P21. Both, B and C rings have half chair conformation and are in cis junction. The N-methyl and C14-hydroxyl groups are in equatorial and axial positions, respectively. The OH-group forms intramolecular hydrogen bond with N atom. Conformation of the molecule is quite different from that found in chelidonine-p-brombenzoateCBB)

Crystal and Molecular Structure of 3B-Hydroxy-14,15B-epoxy- 5\u27B,14B-card-20,22-enolide (Digirezigenin)

The title compound C23H3204 and its methyl-suberate ester were discovered in Ch\u27an Su, the dried venom of the Chinese toad. Its crystals are orthorhombic, space group P21212i, and quasi- isostructural with those of the related compound digitoxigenin (C23H340 4) . The structure was solved by direct methods and refined by least squares technique to a conventional R index of 0.059 for 2271 unique diffractometer observations. The presence of the rigid 14, 15~-epoxy ring alters considerably the shape of ring D (17E) relative to that in digitoxigenin (14E). However, it has little effect upon the general features of the 14-iso-aethiocholane skeleton and the conformation of the y-lactone ring. The amount of rotation about the C(l 7)-C(20) bond is hardly changed while the distance between the position of the carbonyl O relative to digitoxigenin is only 33.2 pm. The conformation of the title compound is also compared with that of a bufa-20, 22-dienolide (cinobufagin) which also possesses a 14, 15~-oxirane ring

PartiaI Syntheses of 21,27 -Bisnordemissidine from Epiandrosterone and Dehydroepiandrosterone Acetates. Crystal and Molecular Structure of 21,27 -Bisnordemissidine Hydrobromide

Stereoselective syntheses of 21,27-bisnordemissidine from epiandrosterone acetate (1) and dehydroepiandrosterone acetate (la) are described in this work. These syntheses involve in sequence: a) stereospecific addition of «-picolyl-Iithium to the C-17 carbonyl group of 1 (la); b) regio- and chemoselective 17,20-dehydration of the formed diol 2 (2a) leading to 3~-acetoxy-17-picolinylidene- -5a-androstane (3) or the corresponding derivative 3a; c) regiospecific allylic oxidation of C-16 in 3 (3a) by Se02 to 4 and chromic acid oxidation to the crucial intermediates (5a-5d); d) stereospecific intramolecular reductive cyclization reaction of 5a-5d, under carefully chosen reaction conditions, leading to 3~-acetoxy- -21,27-bisnor-5a-solanidane (6); e) hydrolysis of 6 with conc. aq. HBr to the target molecule of 21,27-bisnordemissidine hydrobromide (7); and f) alkaline treatment of 6 and 7 with KOH in MeOH affording 21,27-bisnordemissidine (11). The structure of 7 has been unambiguously proved by the appropriate X-ray structural analysis. Detection and isolation of some intermediates and by-products (8, 9 and 10) during catalytic hydrogenation of 5c and 5d pointed to a possible mechanism of the last and crucial step of the synthesis of 21,27-bisnordemissidine

PartiaI Syntheses of 21,27 -Bisnordemissidine from Epiandrosterone and Dehydroepiandrosterone Acetates. Crystal and Molecular Structure of 21,27 -Bisnordemissidine Hydrobromide

Stereoselective syntheses of 21,27-bisnordemissidine from epiandrosterone acetate (1) and dehydroepiandrosterone acetate (la) are described in this work. These syntheses involve in sequence: a) stereospecific addition of «-picolyl-Iithium to the C-17 carbonyl group of 1 (la); b) regio- and chemoselective 17,20-dehydration of the formed diol 2 (2a) leading to 3~-acetoxy-17-picolinylidene- -5a-androstane (3) or the corresponding derivative 3a; c) regiospecific allylic oxidation of C-16 in 3 (3a) by Se02 to 4 and chromic acid oxidation to the crucial intermediates (5a-5d); d) stereospecific intramolecular reductive cyclization reaction of 5a-5d, under carefully chosen reaction conditions, leading to 3~-acetoxy- -21,27-bisnor-5a-solanidane (6); e) hydrolysis of 6 with conc. aq. HBr to the target molecule of 21,27-bisnordemissidine hydrobromide (7); and f) alkaline treatment of 6 and 7 with KOH in MeOH affording 21,27-bisnordemissidine (11). The structure of 7 has been unambiguously proved by the appropriate X-ray structural analysis. Detection and isolation of some intermediates and by-products (8, 9 and 10) during catalytic hydrogenation of 5c and 5d pointed to a possible mechanism of the last and crucial step of the synthesis of 21,27-bisnordemissidine

The Crystal Structure of the Complex [Y(H20)s(N03)2] [Y(H20)2(N03)4]

The title compound was prepared by thermal d\u27ecomposition of crystals of Y (H20)4(N03)s · 2H20. The structure was solved by. Patterson and Fourier methods and isotropically refined to R=0.12. The unit cell is orthorhombic; the space group is C2221 The crystal contains two crystallographically and chemically different complex ions, with yttrium atoms as the center of the complexes. The coordination number of the ion Y (H20h(N08)4 is 10, while the ion Y (H20)5(N03)2 has coordination number 9

Kristalna i molekulska struktura fotodegradacionog proizvoda nizoldipina

Potential and generally selective antihypertensive and antianginal activities of nisoldipine have initiated the study of its molecular structure. The single crystals, which are the potential photodegradation products, were crystallized from methanol solution of nisoldipine, which was exposed to the action of the daylight. They were assumed to be the nitrozo derivatives of nisoldipine with the melting point 151-152°C. The crystal and molecular structure was determined by the X-ray diffraction method (MoKα, λ=0.71073A). On the basis of 3858 independent reflection intensities, the structure was solved by the direct method using the program SHELXS83 and refined by the least squares method (SHELXL93) up to final R-factor R=0.0578 for 1953 reflection (F0>4σ(F0)) and 334 parameters. The molecular structure obtained was that of: isobutyl methyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydro pyridine -3,5 dicarboxylate which confirmed that we are dealing with nisoldipine, so one should not speak about the presence of any assumed photodegradation product. .Potencijalna i u opštem slučaju selektivna antihipertenzivna i antianginozna aktivnost nizoldipina kao i njegova izuzetna fotosenzitivnost na dnevnom svetlu, inicirala je istraživanje njegove molekulske strukture kao i molekulske strukture njegovih produkata. Iz metanolnog rastvora nizoldipina izloženog dejstvu dnevne svetlosti dobijeni su kristalizacijom potencijalni produkti fotodegradacije. Pretpostavljeno je da se radi o nitrozo derivatu nizoldipina, tačke topljenja 151-152°C. Kristalna i molekulska struktura određena je metodom difrakcije rendgenskih zraka (MoKα, λ=0.71073A). Na osnovu 3858 izmerenih intenziteta refleksa rešena je molekulska struktura, direktnom metodom primenom programa SHELXS83 i utačnjena metodom najmanjih kvadrata (SHELXL93) do konačnog R-faktora R=0.0578 za 1953 refleksa (F0>4σ(F0)) i 334 parametra. Dobijena molekulska struktura: izobutil metil-2,6-dimetil-4-(2-nitrofenil)-1,4-dihidropiridin-3,5-dikarboksilat, potvrdila je da se radi o nizoldipinu i da nema osnova govoriti da kristali pripadaju nekom od pretpostavljenih produkata fotodegradacije.

Crystal and Molecular Structure of 3B-Hydroxy-14,15B-epoxy- 5\u27B,14B-card-20,22-enolide (Digirezigenin)

The title compound C23H3204 and its methyl-suberate ester were discovered in Ch\u27an Su, the dried venom of the Chinese toad. Its crystals are orthorhombic, space group P21212i, and quasi- isostructural with those of the related compound digitoxigenin (C23H340 4) . The structure was solved by direct methods and refined by least squares technique to a conventional R index of 0.059 for 2271 unique diffractometer observations. The presence of the rigid 14, 15~-epoxy ring alters considerably the shape of ring D (17E) relative to that in digitoxigenin (14E). However, it has little effect upon the general features of the 14-iso-aethiocholane skeleton and the conformation of the y-lactone ring. The amount of rotation about the C(l 7)-C(20) bond is hardly changed while the distance between the position of the carbonyl O relative to digitoxigenin is only 33.2 pm. The conformation of the title compound is also compared with that of a bufa-20, 22-dienolide (cinobufagin) which also possesses a 14, 15~-oxirane ring

The Crystal and Molecular Structure of 5α-Cholestane-3,6-dione

The crystals of 5a-cholestane-3,6-dione (C27H44O2) are monoclinic, space group P2i with a= 1.9695(3), 6-0.7593(3), c = 0.8176(6) run, /?=92.78(3)°, V= 1.221(1) nm3 and Z=2. The structure was solved by the direct method and refined by the least squares technique to a conventional R = 0.097 for 2220 unique diffractometer observations. Ring D assumed an envelope shape. The side chain equatorially attached to C17 assumed open »zig-zag« conformation

Crystal and Molecular Structure of Chelidonine

The crystal and molecular structure of benzophenantridine alkaloid chelidonine, C20H19N05 CM = 353.37) was solved by direct methods and refined by the least-squares technique to a conventional R index of 0.117 for 1888 unique reflections. The crystals are monoclinic, space group P21. Both, B and C rings have half chair conformation and are in cis junction. The N-methyl and C14-hydroxyl groups are in equatorial and axial positions, respectively. The OH-group forms intramolecular hydrogen bond with N atom. Conformation of the molecule is quite different from that found in chelidonine-p-brombenzoateCBB)