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The three title compounds, namely (Z)-1-(4,5-dinitroimidazol-1-yl)-3-morpholinopropan-2-one 2,4-dinitrophenylhydrazone, C 16 H 17 N 9 O 9 , (IV), (Z)-3-morpholino-1-(4-morpholino-5-nitro-imidazol-1-yl)propan-2-one 2,4-dinitrophenylhydrazone, C 20 -H 25 N 9 O 8 , (Va), and (E)-3-morpholino-1-(4-morpholino-5-nitroimidazol-1-yl)propan-2-one 2,4-dinitrophenylhydrazone tetrahydrofuran solvate, C 20 H 25 N 9 O 8 .C 4 H 8 O, (Vb), have been prepared and their structures determined. In (IV), the C-4 nitro group is nearly perpendicular to the imidazole ring and the C-4-NO 2 bond length is comparable to the value for a normal single Csp 2 -NO 2 bond. In (IV), (Va) and (Vb), the C-5 nitro group deviates insignificantly from the imidazole plane and the C-5-NO 2 bond length is far shorter in all three compounds than C-4-NO 2 in (IV). In consequence, the C-4 nitro group in (IV) is easily replaced by morpholine, while the C-5 nitro group in (IV), (Va) and (Vb) shows an extraordinary stability on treatment with the amine. The E configuration in (Vb) is stabilized by a three-centre hydrogen bond.

3-Chloro-1-(4-nitro-5-piperidinylimidazol-1-yl)propan-2-ol, C 11 H 17 CIN 4 O 3 , (3), is formed together with its unstable isomer 3-chloro-1-(5-nitro-4-piperidinylimidazol-1-yl)propan-2-ol, (2), by treatment of 3-chloro-1-(4,5-dinitroimidazol-1-yl)propan-2-ol, C 6 H 7 ClN 4 O 5 , (1), with piperidine in a 1:2 ratio. In order to explain the position of the piperidine residue in the two isomeric products, (2) and (3), the X-ray investigation of the stable isomer, (3), was undertaken. It has two enantiomers, and in the centrosymmetric crystal lattice both enantiomers of (3) are present. In the asymmetric unit, four molecules of (3) are linked into two dimers, A/B [(S)-enantiomers] and CID [(R)-enantiomers], by two three-centre hydrogen bonds. The piperidine least-squares plane is nearly perpendicular to the planar imidazole system and the nitro group lies approximately in the plane of the imidazole ring. In (1), both nitro groups are rotated significantly from the imidazole plane and can be replaced by piperidine rings. The asymmetric unit contains only one molecule of (1). In the crystal lattice of(1), molecules are linked in chains by hydrogen bonds.

The two new triterpene lactones, 11α-hydroxy-28-methoxy-28-oxo-2,3-dinor-18β-olean-12-en-1,4-olide hydrate [C 29 H 44 O 5 .H 2 O, (5)] and 28-methoxy-28-oxo-1,2.-dinor-10α,18β-oleano-9,12-dien-3,10β-olide [C 29 H 42 O 4 , (6)], were obtained according to the method of Zaprutko [Pol. J. Chem. (1995), 69, 1003-1012]. In both compounds, the lactone bridge connects atoms C4 and C10. In (5), the carbonyl group of the lactone bridge is formed by C1 and O1, and in (6), by C3 and O2. In (5), the methyl group at C10 has a β and in (6) an α configuration. The A and B rings are trans-fused in (5), and cis-fused in (6). The bond lengths in ring C indicate double bonds between C12-C13 in (5) and C9-C11 and C12-C13 in (6). The hydroxyl group at C11 in (5) is α oriented. Ring B in (5) has a chair conformation and in (6) a distorted half-chair conformation. Ring C in (5) has a sofa conformation and in (6) a slightly distorted half-chair conformation. Rings D and E have a chair conformation in both compounds and are cis-fused. The asymmetric unit of (5) contains one water molecule, disordered over two positions, making two alternative hydrogen bonds.

The X-ray crystal structure analyses of three new triterpene lactones (C29H42O6), namely 9β-hydroxy-28-methoxy-11,28-dioxo-1,2-dinor-10α-18β-olean-12-en-3,10β- olide, (3), its 18α- and 9α,18α-isomers, (4) and (5) [9β-hydroxy-28-methoxy-11,28-dioxo-1,2-dinor-10α-18α-olean-12-en-3,10β- olide and 9α-hydroxy-28-methoxy-11,28-dioxo-1,2-dinor-10α-18α-olean-12-en-3,10β- olide, respectively], are described. Compounds (3)–(5) are obtained by treatment of 3β-hydroxy-11-oxo-18α-olean-12-en-28-oic acid methyl ester, (1), with sodium dichromate in acetic acid. In compounds (3)–(5) the six-membered ring A of (1) is replaced by a γ-lactone ring. In contrast to compound (1), the C25 methyl group at C10 has α configuration. The newly introduced hydroxyl group at C9 is β-oriented in compounds (3) and (4), and α oriented in (5). Ring B in (3) has a boat form, but in (4) and (5) it has different equivalent chair conformations. Ring C in (3) has a sofa form, in (4), it has a slightly distorted half-chair form and in (5), it has a conformation intermediate between the half-chair and sofa forms. Rings D and E have chair conformations in all three compounds and are trans-fused in compounds (4), (5) and (1) and cis-fused in (3). In contrast to compound (1), rings A/B in compounds (3)–(5) and rings B/C in compounds (3) and (4) are cis-fused. In compounds (3)–(5), formation of hydrogen bonds has been observed. Inversion of the α configuration to a β configuration at C18 in oleanolic acid derivatives [transformation of (1) to (3)] has been observed for the first time. The triterpene lactones (3)–(5) are the first known oleanan derivatives with cis-fused A/B [(3)–(5)] and B/C rings [(3) and (4)].

The title molecular complex, 4-(5-nitro-1H-indazol-3-yl)piperazin-1-ium 3,5-dinitroindazolide, C 11 H 14 N 5 O 2 + .C 7 H 3 N 4 O 4 − .CH 3 OH, (5), was obtained by treatment of 2,5-dinitroindazole with piperazine in methanol. It consists of 3,5-dinitroindazole (molecule A), 5-nitro-3-piperazinoindazole (molecule B) and methanol. The structure of (5) is discussed on the basis of X-ray analysis and literature data. Molecule B forms a H 2 N + < ammonium cation with a positive charge in the piperazine moiety as a result of the incorporation of the pyrrolic H atom of molecule A. The pyridinic and pyrrolic N atoms of molecule A are linked by hydrogen bonds to the piperazine N atom of molecule B and the O atom of methanol, respectively

The X-ray crystal structure analysis of 3β-hydroxy-28-methoxy-11,28-dioxo-2-oxaolean-12-ene-3,1-carbolactone, (2), and dimethyl 1,3,11-trioxo-1,2-secoolean-12-ene-2,28-dioate, (3), confirms the structure of (2) and (3) previously derived by spectroscopic methods. The hydroxyl group at C(3) in (2) and the side chain at C(5) in (3) are in equatorial positions. In (3), the C(1)=O(4) carbonyl group is antiperiplanar with respect to the C(25) methyl group, the C(3)=O(1) carbonyl group synperiplanar relative to the C(5)-C(6) bond and anticlinal to the C(2)=O(3) carbonyl group. In both compounds, C(28), O(6), O(7) and C(31) in the C(17) ester group are coplanar; the torsion angles C(18)-C(17)-C(28)-O(6) are quite different. The position of the ester group in (2) is stabilized by an intermolecular hydrogen bond. In both compounds, ring C has a slightly distorted sofa conformation; all other rings have deformed chair conformations. Rings D and E are cis-fused

The title molecular complex, piperidinium indazolide, 2C 5 H 12 N + .2C 7 H 3 N 4 O 4 - , was obtained by treatment of 3,5-dinitroindazole with piperidine. It consists of two ionized molecules of each component, connected by hydrogen bonds. The piperidine molecules form H 2 N + < ammonium cations as a result of the incorporation of the pyrrolic H atoms of (1). The complex occupies a general position in the crystal lattice. The structure of the complex is determined on the basis of IR and 1 H-NMR spectra as well as X-ray analysis

The structures of 5-nitro-3-thiomorpholino-1H-indazole, C(11)H(12)N(4)O(2)S, (IIa), and 3-(4-methylpiperazino)-5-nitro-1H-indazole-methanol-water (2/1/1), 2C(12)H(15)N(5)O(2).CH(3)OH.H(2)O, (IIIa), are described. In the crystal lattice of (IIa), the molecules are linked into dimers by N-H...N hydrogen bonds. The asymmetric unit of (IIIa) contains two independent molecules of the indazole moiety, one molecule of methanol and one of water. The three components of (IIIa) are linked by hydrogen bonds to form double chains running along the x axis. pi-Stacking involving the indazole moieties occurs in both compounds.

The structure analyses of racemic 3-chloro-1-(4-morpholino-5-nitroimidazol-1-yl)propan-2-ol, C 1 0H 1 5CIN 4 O 4 , (II), and 3-chloro-1-(5-morpholino-4-nitroimidazol-1-yl)propan-2-ol, C 1 0H 1 5CIN 4 O 4 , (III), have been undertaken in order to determine the position of the morpholine residue in these two isomers. The morphine residue in (II) is connected at the 4-position, while in (III), it is connected at the 5-position of the imidazole ring. The morpholine mean planes and nitro groups in the two compounds deviate from the imidazole planes to different extents. The nitro groups in (II) and (III) take part in the conjugation system of the imidazole rings. In consequence, the exocyclic C−N bonds are significantly shorter than the normal single Csp 2 −NO 2 bond and the nitro groups in (II) and (III) show an extraordinary stability on treatment with morpholine and piperidine [Gzella, Wrzeciono & Pοppel (1999). Acta Cryst. C55, 1562-1565]. In the crystal lattice, the molecules of both compounds are linked by O−H...N and C−H...O intermolecular hydrogen bonds.

C 4 H 12 N 2 2+ •2C 7 H 3 N 4 O 4 − •2H 2 O cristallise dans P2 1 /c avec a=12,818, b=13,769, c=6,701 A , β=104,60°, Z=2; affinement jusqu'a R=0,035. Le cycle piperazinium resulte de l'incorporation de deux protons des atomes N du cycle pyrrole. L'indazole est legerement plisse, le maximum de deviation par rapport au plan des moindes carres est de 0,034 A. Le cation possede une conformation chaise et forme un angle de 85,1° avec l'indazole. Le cristal contient un reseau de liaisons hydrogene, dans lequel l'eau joue le role de donneur et accepteur

4-Nitropyrazolderivate 1a–1c und 1g–1j reagieren mit dem Carbanion von Chlormethyl-p-tolylsulfon (2) unter stellvertretender nucleophiler Substitution von Wasserstoff in Position 5. Die Anwesenheit einer zweiten Nitrogruppe in Stellung 3 (1c) oder 2′ (1h) setzt die Ausbeute der Reaktion bedeutend herab. Aus 1d und 1e wurden keine Substitutionsprodukte erhalten. Bei 1f erfolgt die Substitution in Position 4. Bei der Einwirkung von 2 auf 1h und 1j entstehen die Nebenprodukte 3h1 und 4/4a bzw. 3j1, 3j2 und 5. Azoles, 261). - Vicarious Nucleophilic Substitution of Hydrogen in Nitropyrazole Derivatives 4-Nitropyrazoles 1a–1c and 1g–1j react with the carbanion derived from chloromethyl p-tolyl sulfone (2) to give products of the vicarious nucleophilic substitution (VNS) of hydrogen at position 5. The presence of a second nitro group at position 3 (1c) or 2′ (1h) decreases the yield of the reaction considerably. 1d and 1e does not give products of VNS with 2. In 1f the substitution takes place at position 4. On treating with 2, 1h and 1j give the byproducts 3h1, 4/4a and 3j1, 3j2, 5, respectively.

Triterpenoids, 5. — Synthesis and Structure Elucidation of Some New 18α-Oleanolic Acid Derivatives On treatment with hydrogen bromide, 3β-acetoxy-11-oxoolean-12-en-28-oic acid methyl ester (1) affords the expected 18α-diastereomer 2 and the unknown 3-isopropyl-11-oxo-4-nor-18α-oleana-3(5),12-dien-28-oic acid methyl ester (3) as product of a Wagner-Meerwein rearrangement accompanied by the migration of the new introduced exocyclic double bond. Alkaline hydrolysis of 2 gives the known methyl ester 5 together with the new 3β,11-dihydroxy-12-oxooleana-9(11),13(18)-dien-28-oic acid methyl ester (4). The byproducts 3 and 4 can also be obtained by treatment of 5 with acetic anhydride (3) or KOH/ethanol (4), respectively. The structure elucidation of 3 and 4 is described. The structure of 4 was confirmed by X-ray analysis.

(C 7 H 4 N 4 O 4 •C 4 H 9 NS) 2 cristallise dans C2/c avec a=20,751, b=6,782, c=20,339 A, β=102,99°, Z=4; affinement jusqu'a R=0,040. Le complexe repose sur l'axe d'ordre 2. La molecule thiomorpholine forme un cation ammonium resultant de l'incorporation d'un proton de l'atome N du pyrrole de l'indazole. Le systeme indazole est approximativement plan. Le cation thiomorpholinium a une conformation chaise. Les molecules sont liees par des liaisons hydrogene

(C 7 H 4 N 4 O 4 .C 4 H 9 N) 2 cristallise dans P2 1 /n avec a=19,917, b=9,751, c=6,703 A, β=90,90°, Z=2; affinement jusqu'a R=0,055. Le compose comprend deux molecules de 3,5-dinitroindazole et deux molecules de pyrrolidine, liees par des liaisons hydrogene et situees sur un centre de symetrie. Les molecules sont dans des formes ionisees. La molecule pyrolidine forme un cation ammonium resultant de l'incorporation d'un proton a partir de l'atome N du pyrrole dans la molecule indazole

The 13C NMR spectra of five pairs of 18β- and 18°-11-oxooleanolic acid derivatives have been assigned. The chemical shifts of C-12, C-13, C-17, C-18 and C-28 are of diagnostic value for the determination of the D/E junction stereochemistry.

The aminopyrazole (I) reacts with DMF (II) to give the formylated amidine (III) which is hydrolyzed, yielding the 4-formyl derivative (IV) of (I).

The X-ray crystal structure analyses of two triterpene isoxazoles, namely olean-2,12-dieno[2,3-d]isoxazol-28-oic acid methyl ester {methyl isoxazolo[4,5-b]olean-2,12-dien-28-oate, C 32 H 47 NO 3 , (2a)} and 19β,28-epoxy-18α-olean-2-eno[2,3-d]isoxazole {19β,28-epoxy-isoxazolo[4,5-b]-18α-olean-2-ene, C 31 H 47 NO 2 , (4a)} are described. These compounds were obtained by treatment of 2-formyl- or 2-hydroxymethylene derivatives of 3-oxoolean-12-en-28-oic methyl ester, (la) and (1b), and 19β,28-epoxy-18Hα-oleanan-3-one, (3a) and (3b), with hydroxylamine hydrochloride according to the method described by Govardhan, Reddy, Ramaiah & Rao [J. Indian Chem. Soc. (1983), pp. 858-860] for the synthesis of ring-A-fused triterpene [3,2-c]isoxazoles. The structures of the obtained [2,3-d]isoxazoles, (2a) and (4a), were confirmed by the comparison of the bord lengths and bord angles found for the isoxazole rings of compounds (2a) and (4a) with the corresponding data given in the literature. The isoxazole rings in both compounds are planar. Ring A in (2a) and (4a) has a conformation between the half-chair and sofa form. Rings B. D and E in (2a), and B, C, D and E in (4a) have the chair conformation. Ring C in (2a) has a distorted sofa form. In (2a), the rings A/B, B/C and C/D are trans-fused and the rings DIE cis-fused. In (4a), the A/B, B/C, C/D and DIE ring junctions are trans. The axial 02 and C28 atoms in (4a) are β oriented and form, together with the C17. C18 and C19 atoms, the five-membered ring F, which has an envelope conformation.