Chiral Steroidal Phosphines: Synthesis and Platinum Complexes

Summary.  The synthesis of novel 3- and 17-diphenylphosphino-androstane derivatives via homogeneous catalytic P-C coupling is described. The products were characterized by ¹H and ³¹P NMR measurements. According to the NMR investigation of the PtCl₂P₂-type complexes, the steroidal phosphines are trans-coordinated with respect to the Pt-centre exclusively. Received June 14, 2000. Accepted (revised) July 24, 2000     

NORMAL VIBRATIONAL ANALYSIS OF TRANS-POLYACETYLENE

The results of normal vibrational analyses of trans, trans-2, 4-hexadiene and the backbone of trans, trans-1, 4-diphenyl-butadiene were used in the normal mode computation of trans-polyacetylene (PA). Only 8 non-zero calculated frequencies were obtained which obeys the rule of 3N-4. The potential energy distribution (PED) data were in good agreement with the empirical assignment of Shirakawa et al. and Kozmany, but most of the vibrational frequencies of trans-PA had contributions from several empirical modes, indicationg the more complieacy in trans-PA molecular vibration than in the model molecule case. The calculated C=C and C—C stretching frequencies of trans-PA were over 200cm~(-1) higher and lower than the observed ones, respectively, due to the longer effective conjugate length in the trans-PA. This was shown by the dependence of the PED-weighted average frequencies of C=C and C—C stretchings on the force constants f(C=C)~2 and f(C—C)~2.     

Synthese und Strukturaufklärung von Pyrimidobenzimidazolen und kondensierten Derivaten, 3. Mitt. [1,2]. Decahydropyrimido[1,2-<Emphasis Type="Italic">a</Emphasis>]benzimidazol-2-ole und Octahydropyrimido[1,2-<Emphasis Type="Italic">a</Emphasis>]benzimidazole

Zusammenfassung.  Die Reaktion von racemischem trans-Hexahydrobenzimidazol-2-amin mit drei ausgew?hlten vinylogen Ketonen unter milden Bedingungen wurde untersucht. Nur im Fall der Umsetzung mit 4-Phenyl-3-buten-2-on konnten Cycloadditionsprodukte isoliert werden. Diese sind laut NMR-Analysen Gemische von zwei der acht m?glichen Diastereomeren, n?mlich von rac-2β-Methyl-4β-phenyl-trans-5aα- und trans-5aβ-decahydropyrimido[1,2-a]benzimidazol-2α-ol. Bei Umsetzungen des Amins mit Phenylbutenon bei erhoühten Temperatur sowie mit, 2-Methyl-1-phenyl-1-penten-3-on und 4^′-Chlorchalkon bildeten sich Gemische entsprechend substituierter rac-4α-Phenyl-trans-5aβ- und trans-5aα-octahydropyrimido[1,2-a]benzimidazole. Struktur und Stereochemie der Titelverbindungen und ihrer Hydrochloride wurden anhand NMR-spektroskopischer Untersuchungen aufgekl?rt. Die Ringschlu?reaktionen verlaufen in allen F?llen gleichgerichtet regio-, jedoch nicht diastereoselektiv. Versuche zur Beeinflussung der Regio- und/oder Diastereoselektivit?t der Cyclisierungsreaktion durch Variation der Reaktionsbedingungen hatten keinen Erfolg.

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Synthesis and Structure Elucidation of Pyrimidobenzimidazoles and Fused Derivatives III [1,2]. Decahydropyrimido[1,2- a ]benzimidazol-2-oles and Octahydropyrimido[1,2- a ]benzimidazoles

Summary.  The reaction of racemic trans-hexahydrobenzimidazol-2-amine with three vinylogous ketones under mild conditions was studied. Only in the case of 4-phenyl-3-buten-2-one cycloaddition products could be isolated. According to NMR spectroscopy they consist of mixtures of two of eight possible diastereomers: rac-2β-methyl-4β-phenyl-trans-5aα- and trans-5aβ-decahydropyrimido[1,2-a]benzimidazol-2α-ole. Reaction of the amine with the butenone at higher temperature and with, 2-methyl-1-phenyl-1-penten-3-one, and 4^′-chlorochalcone afforded mixtures of two diastereomers each, which turned out as rac-4α-phenyl-trans-5aβ- and trans-5aα-octahydropyrimido[1,2-a]benzimidazoles. Complete structural and stereochemical assignments of the title compounds and their hydrochlorides were established by NMR spectroscopic investigations. The results showed that all investigated cyclization reactions proceeded regioselectively with equal orientation of the components, but not diastereoselectively. Variation of the reaction conditions did influence neither regio- nor diastereoselectivity.

Received October 19, 2000. Accepted October 30, 2000     

Quantitative estimation of trans-1,4 and cis-1,4 isomers in polychloroprene by high-resolution NMR

In the ¹H-NMR spectrum of polychloroprene dissolved in C₆D₆, the ?CH proton signal was separated into two triplet peaks. These triplet signals were assigned to the ?CH proton in the trans-1,4 and cis-1,4 isomers by measurement of ¹H-NMR spectra of 3-chloro-1-butene and a mixture of trans- and cis-2-chloro-2-butene as model compounds for the 1,2, trans-1,4 and cis-1,4 isomers. In ¹H-NMR spectra (220 Mcps) of polychloroprene dissolved in C₆D₆, two triplet signals were separated completely from which the relative concentrations of trans-1,4 and cis-1,4 isomers could be obtained quantitatively.     

A Novel Infinite 1-D Chain of Silver(I) Bridged by trans-Azobenzene

Summary.  The self-assembly of Ag[BF₄] with trans-azobenzene in dichloromethane yields a new coordination polymer ([Ag(μ-trans-azobenzene)H₂O][BF₄])_n which was characterized by X-ray single crystal diffraction. The crystal consists of 1-D zigzag cationic chains made up from [Ag(H₂O)]⁺ units linked by trans-azobenzene bridges and BF⁻ ₄ anions. Hydrogen bonding interactions between the chains and BF⁻ ₄ anions occur via intermolecular C*H⋯F and O*H⋯F contacts, and the crystal displays a 2-D supramolecular structure. Received May 31, 2000. Accepted June 30, 2000     

Kinetics and mechanism of reaction of trans-(diaqua)(N,N′-ethylene-bis-salicylidenimine) chromium(iii) with sulfur(iv): The labilizing effect of coordinated sulfite

The reaction of trans-[Cr(Salen)(OH₂)₂]⁺ with aqueous sulfite yields trans-[Cr(Salen)(OH₂)(OSO₂(SINGLEBOND)O)]⁻ (O-bonded isomer). The rate and activation parameter data for the formation of the sulfito complex are consistent with a mechanism involving rate-limiting addition of SO₂ to the Cr^III(SINGLEBOND)OH bond. The complex ions, trans-[(OH₂)Cr(Salen)(OSO₂(SINGLEBOND)O)]⁻, and trans-[(OH)Cr(Salen)(OSO₂(SINGLEBOND)O)]²⁻, undergo reversible anation by NCS⁻, N₃⁻, imidazole, and pyridine resulting in the formation of trans-[XCr(Salen)(OSO₂(SINGLEBOND)O)]^(N+1)−(n=1 for X=N₃⁻,NCS⁻, and 0 for X=imidazole and pyridine) predominantly via dissociative interchange mechanism. The labilizing action of the coordinated sulfite on the trans-Cr^III-X bond in trans-[XCr(Salen)(OSO₂)]⁽ⁿ⁺¹⁾⁻ follows the sequence: NCS⁻pyridine ca. N₃⁻ ca. imidazole. Data analysis indicated that the coordinated sulfite has little trans activating influence. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 373–384, 1998     

Synthesis of per-O-(carboxymethyl)calix[4]pyrogallols and their complexation with some alkaline metal and lanthanide ions

Complexones of a new class, viz., carboxy-functionalized calix[4]pyrrogallols, were synthesized. The per-O-(carboxymethyl)calix[4]pyrogallols obtained were established to exist in the (rel, cis, trans, trans)-configuration by 2D NMR spectroscopic data. According to the pH-potentiometric data, the interaction of these compounds with alkaline metal ions (Li⁺, Na⁺, K⁺, Cs⁺) and lanthanide ions (La³⁺, Gd³⁺, Lu³⁺) in a water—DMSO system produces 1 : 1 complexes. The specific features of complexation of per-O-(carboxymethyl)calix[4]pyrogallols, as compared to their acyclic analogs, with alkaline metal and lanthanide ions are due to the cooperative effect of donor groups preorganized on the calixarene matrix.     

Light-induced cis/trans isomerization of cis-[Pd(L-S,O)2] and cis-[Pt(L-S,O)2] complexes of chelating N,N-dialkyl-N′-acylthioureas: key to the formation and isolation of trans isomers

Irradiation cis-[M(Lⁿ-S,O)₂] complexes (M = Pt^II, Pd^II) derived from N,N-dialkyl-N′-benzoylthioureas (HLⁿ) with various sources of intense visible polychromatic or monochromatic light with λ < 500 nm leads to light-induced cis?→?trans isomerization in organic solvents. In all cases, white light derived from several sources or monochromatic blue-violet laser 405 nm light, efficiently results in substantial amounts of the trans isomer appearing in solution, as shown by ¹H NMR and/or reversed-phase HPLC separation in dilute solutions at room temperature. The extent and relative rates of cis/trans isomerization induced by in situ laser light (λ = 405 nm) of cis-[Pd(L²-S,O)₂] was directly monitored by ¹H NMR and ¹⁹⁵Pt NMR spectroscopy of selected cis-[Pt(L-S,O)₂] compounds in chloroform-d; both with and without light irradiation allows the δ(¹⁹⁵Pt) chemical shifts cis/trans isomer pairs to be recorded. The cis/trans isomers appear to be in a photo-thermal equilibrium between the thermodynamically favored cis isomer and its trans counterpart. In the dark, the trans isomer reverts back to the cis complex in what is probably a thermal process. The light-induced cis/trans process is the key to preparing and isolating the rare trans complexes which cannot be prepared by conventional synthesis as confirmed by the first example of trans-[Pd(L-S,O)₂] characterized by single-crystal X-ray diffraction, deliberately prepared after photo-induced isomerization in acetonitrile solution.     

The reactive states of ions: Octatrienes and dimethyl substituted cyclohexadienes

The principal decomposition routes of molecular ions of cis, cis, cis-2,4,6-octatriene, cis, cis, trans-2,4,6-octatriene, trans, cis, trans-2,4,6-octatriene, trans-5,6-dimethyl-1,3-cyclohexadiene and cis-5,6-dimethyl-1,3-cyclohexadiene were studied using ion kinetic spectroscopy. The loss of radicals from [M]⁺· appears to proceed via a ground state, while loss of a neutral molecule appears to involve either complete equilibration of structure within the system or both ground state and excited state pathways.     

1H and 13C NMR studies of some germacrones and isogermacrones

The ¹H and ¹³C NMR spectra of the trans,trans-, cis,cis- and cis-C-3–C-4, trans-C-7–C-8-germacrones and of the cis-C-2–C-3, trans-C-7–C–8, trans-C-2–C-3, cis-C-7–C-8- and cis,cis-isogermacrones are analysed. The last two isogermacrones are new compounds. The C-2–C-3 double bond in the previously described isogermacrone is found to be of cis configuration, contrary to the hitherto accepted trans arrangement.     

Synthesis of Enantiopure Chiral Perhydrobenzimidazole and Hexahydroquinoxaline Derivatives

Summary.  Starting from 2-anilino-2-ethoxy-3-oxothiobutyric acid anilides and (R, R)-or (S, S)-trans-1,2-diaminocyclohexane, chiral C2-disubstituted perhydrobenzimidazole and trans-4a,5,6,7,8,8a-hexahydroquinoxaline derivatives were obtained depending on the polarity of the solvent. Received April 10, 2000. Accepted May 2, 2000     

Preparation and Fungitoxicity of Some Dibromo-8-quinolinols

Summary.  2,5-, 3,5-, 3,6-, 3,7-, 4,5-, 5,6-, 5,7-, and 6,7-dibromo-8-quinolinols were prepared and tested against six fungi (Aspergillus niger, Aspergillus oryzae, Myrothecium verrucaria, Trichoderma viride, Mucor cirinelloides, and Trichophyton mentagrophytes) in Sabouraud dextrose broth. Most of the compounds were strongly antifungal, inhibiting five of the fungi below 1μg/cm³, but were somewhat less fungitoxic than the corresponding chloro analogues. M. cirinelloides was not inhibited by any of the compounds except 4,5-dibromo-8-quinolinol. This high level of fungitoxicity is attributed to intramolecular synergism. Received December 28, 2000. Accepted (revised) February 3, 2001     

Ruthenium Tris-pyrazolylborate Complexes XVII [1]. Structure and Bonding in a Series of Ruthenium Hydrido-tris-(pyrazolyl)-borate Cyclooctadiene Complexes

Summary.  The complexes RuTp(cod)X (X = Br⁻ (2), I⁻ (3), CN⁻ (4)) have been obtained by the reaction of RuTp(cod)Cl (1) with KX in boiling MeOH in high yields. The cationic complexes [RuTp(cod)(py)]⁺ (5), [RuTp(cod)(dmso)]⁺ (6), and [RuTp(cod)(CH₃CN)]⁺ (7) were prepared as the CF₃SO₃ ⁻ salts by reacting 1 with 1 equivalent of AgCF₃SO₃ in the presence of the respective co-ligand in CH₂Cl₂. The crystal structures of 1, 3, 4, 5, 6, and 7 are reported. Structural features are discussed in conjunction with ¹H, ¹³C, and ¹⁵N NMR spectroscopic data revealing a linear correlation of ¹⁵N chemical shifts and Ru-N (trans to X(L)) bond distances. Received August 31, 2000. Accepted (revised) October 23, 2000     

Synthesis of (-)-11 Hydroxy-delta8-6a, 10a-trans-tetrahydrocannabinol

When (?)-Δ⁸-6a, 10a-trans-THC (THC = Tetrahydrocannabinol), in the form of its diacetate, was irradiated in the presence of oxygen and a sensitizer, followed by reduction with NaBH₄, three allylic alcohols were formed: (?)-8α-and (?)-8β-hydroxy-Δ^9,11-THC (proportion 3:1) and (?)-9α-hydroxy-Δ^7,8-THC. Acetylation of the epimeric 8-hydroxy-compounds with Ac₂O/pyridine gave the corresponding diacetates. When (?)-Δ⁸-6a, 10a-trans-THC, in the form of its tetrahydropyranyl derivative, was heated with m-chloroperbenzoic acid, the two epimeric 8,9-epoxides were formed in equal amounts. These compounds, on treatment with butyllithium, afforded (?)-8α- and (?)-8β-hydroxy-Δ^9,11- 6a, 10a-trans-THC-tetrahydropyranylether. After removing the protecting group and treatment with Ac₂O/pyridine the same diacetates, as formed by photooxygenation of (?)-Δ⁸-THC-acetate, were obtained as a 1:1-mixture. On heating these epimeric diacetates to 290° they underwent allylic rearrangement to (?)-11-acetoxy-Δ⁸-THC-acetate. From this (?)-11-hydroxy-Δ⁸-6a, 10a-trans-THC was obtained by treatment with LiAlH₄.     

Determination of the geometric structure of three substituted polyacetylenes: Polymethylacetylene,polypentylacetylene, and poly(tbutylacetylene)

The geometric structure of polymethylacetylene (PMA), polypentylacetylene (PPA), and poly(t-butylacetylene) (PTA) was investigated by ¹H NMR, ¹³C NMR, and IR spectroscopies. It was shown that both NMR techniques can be used to determine the trans isomer content of PPA and PTA, whereas the ¹H NMR and IR methods can be used for PMA. A calibration curve was constructed by using the 965- and 720-cm^?1 bands of the IR spectrum of PPA, and could be used in future work for the same purpose if the samples had molecular weights similar to that of the one used in this study. The isomerization kinetics of PTA was investigated and cis^→ trans activation energies of 88 and 121 kJ/mol were calculated in solution and in the solid state, respectively. Heat treatment of the PMA and PPA samples always leads to a cis^→ trans isomerization with a 100% trans content under extreme conditions. Moreover, a cis^→ trans isomerization of PTA was induced in CCl₄, CDCl₃, toluene, and benzene, but a trans^→ cis isomerization was induced in decalin. The reversible isomerization of PTA covered a trans isomer concentration ranging form 25 to 60%.     

Thermisches Verhalten von 1,2-Dipropenylbenzolen

1-cis, 2-cis-Dipropenylbenzene (cis, cis- 1 ) isomerises thermally at 215–235° with 1st order kinetics to give trans, cis- 1 and vice versa. At equilibrium 89% trans, cis- and 11% cis, cis- 1 are present. It is shown by thermal rearrangement of cis, cis-2′, 2″-d₂- 1 that the isomerisation is attributable to aromatic [1, 7a]-sigmatropic H-shifts. trans, trans- 1 rearranges thermally at 225–245° to yield 2, 3-dimethyl-1, 2-dihydronaphthalene ( 2 ). The formation of 2 can be visualized by disrotatory ring closure followed by an aromatic [1, 5s]-sigmatropic H-shift. 2 is also formed when, cis, cis- or trans, cis- 1 are heated for 153 h at 225°. Besides 2 a small amount (3%) of 1-ethyl-1, 2-dihydronaphthalene ( 5 ) is formed. The rearrangement of trans, trans- 1 and trans, trans-2′, 2″-d₂- 1 shows a secondary isotope effect k_H/k_D = 0,90.     

Isolation by HPLC. and Identification by NMR. Spectroscopy of 11 mono-, di- and tri-cis isomers of an aromatic analogue of retinoic acid,ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-nona-2,4,6, 8-tetraenoate

Photoisomerization of an aromatic analogue of retinoic acid, ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-nona-2,4,6, 8-tetraenoate 1 in dilute solutions of hexane, benzene, and ethanol yielded multi-component mixtures of cis isomers which were separated by HPLC. FT-¹H-NMR. at 270 MHz and, in some cases, homonuclear decoupling and Overhauser experiments as well as ¹³C-NMR. were applied to establish the structures of 4 mono-cis, 4 (of 6 possible) di-cis, and 3 (of 4 possible) tri-cis isomers. The structures of 3 isomeric esters, namely (2Z, 4E, 6E, 8E) 6 , (2Z, 4Z, 6E, 8E) 9 , and (2Z, 4Z, 6Z, 8E) 7 were independently confirmed by direct syntheses. The ¹H-NMR. data of all these compounds and the ¹³C-NMR. data of the all-trans and of 6 cis isomers available in sufficiently large quantities are discussed.     

Synthesis and Stereostructure of Saturated Isoindolone-Fused Hetero Tri-, Tetra-, and Pentacyclic Compounds

Summary. t-2-Benzoyl-t-4-phenylcyclohexane-r-1-carboxylic acid reacts with hydrazine to give the saturated 1,7-diphenyl-trans-phthalazin-4(3H)-one. The reaction of the acid with ethylenediamine yields diastereomeric trans-imidazo[2,3-a]isoindoles, which differ in their C-1 configuration. The cyclizations of the acid with cis-2-aminocyclohexane- or 4-cyclohexenemethanol result in trans-isoindolo[2,1-a][3,1]benzoxazines, while in its reactions with the analogous di-endo- and di-exo-norbornane- and -norborneneamino alcohols, the acid gives methylene-bridged isomeric di-endo-norbornanes or a norbornene derivative; the corresponding diastereomeric di-exo derivatives have also been prepared. After isolation, the structures were established by means of ¹H and ¹³C NMR spectroscopy, with application of DIFFNOE, DEPT, HMQC, HMBC, and 2D-COSY techniques.     

Conformational Analysis. XIX properties and reactions of 1,3-oxathianes VIII A 1H NMR conformational study of methyl-substituted derivatives

The addition of thioacetic acid to unsaturated alcohols or acids was utilized to obtain mercaptoalkanols which were condensed with suitable carybonyl compounds to prepare 24 methyl-substituted 1,3-oxathianes. The ¹H NMR spectra of the 1,3-oxathiane products were recorded at 60, 100 and/or 300 MHz and fully analysed. The results are best explained by a chair form which is completely staggered in the C-4? C-5? C-6 moiety ψ₄₅ or (ψ₅₆=60±1°). 1,3-Oxathianes having syn-axial 2,4- (and/or 2,6-) methyl-methyl interactions exist appreciably, if not exclusively, in twist forms. The vicinal coupling constants lead to the conformational free energies of axial methyl groups at C-4, ΔG°=7.4±0.4 kJ mol^?1, and at C-5, ΔG°=3.7±0.3 kJ mol^?1, in good agreement with previous estimates. They also show that both r-4,cis-5,trans-6- and r-4,trans-5,trans-6- trimethyl-1,3-oxathianes greatly favour the chiar form where the methyl group at C-4 is axial. The chair-twist energy parameters are reestimated at ΔH°_CT 27.0 kJ mol^?1, ΔS°_CT 11.6J mol^?1K^?1, and ΔG°_CT(298) 23.5 kJ mol^?1 for a 2,5-twist form.     

Synthesis of difunctional 1,4-dimethyl-1,4-disilacyclohexanes

Transformations of HVinSiCl₂, HVinSi(Me)Cl, HVinSi(Me)Ph, and HVinSi(Me)NEt₂ in the presence of Pt catalyst were studied. In dilute solutions, the reaction gave a mixture of structural and stereoisomers of five- and six-membered disilacyclanes, resulting from intramolecular cyclization of the initially formed linear dimer. In the case of methyl(phenyl)disilacyclane, the structural isomers were separated andtrans-1,4-dimethyl-1,4-diphenyl-1,4-disilacyclohexane was isolated. The reaction of this product with HCl in the presence of AlCl₃ followed by hydrolysis resulted in the synthesis oftrans-1,4-dichloro- andtrans-1,4-dihydroxy-1,4-dimethyl-1,4-disilacyclohexanes. The structures of the structural and stereoisomers synthesized were confirmed by¹H,¹³C, and²⁹Si NMR and IR spectroscopies and mass spectrometry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1734–1738, September, 1999.