Five-membered 2,3-dioxo heterocycles: XCVIII. [4 + 2]-cycloaddition of alkyl vinyl ethers to 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones. A new synthetic approach to heteroanalogs of 13(14→8)-abeo steroids

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with alkyl vinyl ethers according to the [4 + 2]-cycloaddition pattern with formation of substituted (1S*,16R*)- and (1R*,16R*)-16-alkoxy-14-aryl-3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadeca-4,6,8,13-tetraene-2,11,12-triones. The structure of (1S*,16R*)-7-chloro-16-ethoxy-14-phenyl-3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadeca-4,6,8,13-tetraene-2,11,12-trione was determined by X-ray analysis. A new synthetic approach was developed to heteroanalogs of 13(14→8)-abeo steroids, substituted 3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadecanes.     

Chemistry of strained polycyclic compounds—V : The stereospecific cationic cage expansion reaction of 4-homocubane carbinols to 1,3-bishomocubane bridgehead alcohols

The cationic rearrangement of four homocubane bridgehead carbinols viz dimethyl 4-(1-bromopentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonyl-9-one ethylene ketal) carbinol 2, diphenyl 4-(1-bromopentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonyl-9-one ethylene ketal) carbinol 3, 4-(1-bromopentacyclo[4.3.0.0^2,5.0^3,8.0^4,7] nonyl-9-one ethylene ketal) carbinol 4 and 4-(1-bromopentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonyl) carbinol 16, has been studied undervarious conditions.Exclusive migration of the C₄C₇ (or the equivalent C₃C₄ bond) in the homocubane skeleton was observed leading to 1,3-bishomocubane bridgehead alcohols. Relief of cage constraint governs the selective course of these cage expansions.     

Electron transfer from highly strained polycyclic molecules

The details of electron transfer from strained, saturated hydrocarbons in electrochemical oxidations on platinum have been studied. Among the systems investigated were tetracyclo[3.2.0.0^2,7.0^4,6]heptane, tricyclo [4.1.0.0^2,7]heptane, pentacyclo[4.3.0.0^2,4.0^5,7]nonane, pentacyclo[4.4.0.0^2,5.0^3.8.0^4,7] decane, pentacyclo[4.2.0.0^2,5.0^3,8.0^4,7]octane, pentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonane, bicyclo[2.1.0]pentane, and a variety of bicyclo[1.1.0]butane derivatives. The oxidation of 1,2,3-trimethylbicyclo [1.1.0]butane is discussed in detail.     

Synthetic approaches to physiologically active polycyclic compounds: V. Ritter reaction of 4-hydroxyadamantan-2-one

The Ritter reaction of 4-hydroxyadamantan-2-one (with acetonitrile in the presence of boron trifluoride-ether complex and trifluoroacetic acid) takes an unusual path and yields diastereoisomeric 9- methyl-1-(4-oxo-2-adamantyloxy)-8-oxa-10-azatetracyclo[5.3.1^12,6.1^4,11]tridec-9-enes as the major products. Their structure was established by X-ray analysis.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1488–1491.Original Russian Text Copyright © 2004 by Averina, Zefirova, Zefirov, Chekhlov, Shilov, Aldoshin.For communications I-IV, see [1-4].     

Five-membered 2,3-dioxo heterocycles: LXXVII. [4 + 2]-Cycloaddition of alkyl vinyl ethers to 3-aroylpyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazine-1,2,4(4<Emphasis Type="Italic">H</Emphasis>)-triones

[4 + 2]-Cycloaddition of 3-aroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4(4H)-triones to alkyl vinyl ethers gave substituted stereoisomeric (1R*,16R*)- and (1S*,16R*)-16-alkoxy-14-aryl-3,15-dioxa-10-azatetracyclo[8.7.0.0^{1, 13}.0^{4, 9}]heptadeca-4,6,8,13-tetraene-2,11,12-triones.     

3-Substituted pyridines. preparation of 3, 5-dimethylpyridine4-phenyldipyridine,and syntheses based on it

3, 5-Dimethyl-4-phenylpyridine is prepared by catalytic dehydrogenation and N-demethylation of 1, 3, 5-trimethyl-4-phenyl-Δ³-piperidine. Oxidation of the former gives 4-phenylpyridine-3, 5-dicarboxylic acid and the dimethyl ester and bis(diethylamide) of the acid are prepared. The same acid is used to prepare 4-phenylpyridine, methyl 2-azafluorenone-4-carboxylate, and also a compound assumed to be 6,14 dioxo3-azatetracyclo[9. 2. 1. 0^{5, 13}. O^7,12]tetradeca-2, 4, 7, 9, 11, 13-hexaene.     

Selective reductive dimerization of homocubane series oximes

The mixture of di- and monoethylene ketals obtained by the reaction of 1,9-dibromopentacyc lo[5.4.0.0^2,6.0^3,10.0^5,9]-undeca-8,11-dione followed by hydrolysis and ring contraction by Faworsky method was converted into a mixture of ethylene ketals of 7-bromopentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decan-6-one-4- and 5-bromopentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decan-6-one-8-carboxylic acid where the carboxy group was replaced by bromine along the procedure of Hunsdiecker-Borodine-Cristol. 6-Ethylene ketal of the pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8] decan-6-one obtained by the debromination of ethylene ketals of 4,7- and 5,8-dibromopentacyclo[5.3.0.0^2,5.0^3,9.0^4,8] decan-6-one was hydrolyzed to ketone whose oxime was selectively reduced on a platinum catalyst into the di-6-pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decylamine. The reaction of reductive dimerization was also characteristic of pentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]-nonan-9-one and pentacyclo[6.3.0.0^2,6.0^3,10.0^5,9]undecan-4-one oximes, whereas the composition of the reduction products of pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecan-8-one oxime depended on the amount of the catalyst.     

Cubane derivatives

The reduction of 1-bromo-9,9-ethylenedioxypentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonane-4-carboxylic acid (2) with lithium aluminum hydride and aluminum hydride in THF was studied. A new effective method for preparing 1-bromo-9,9-ethylenedioxypentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]-non-4-ylcarbinol (1) based on reduction of2 with AlH₃ under mild conditions was developed.     

Formation of novel polycyclic cage compounds through ‘uncaging’ of readily accessible higher cage compounds

The synthesis of the novel cage compounds 7-halomethyl-8-(carbomethoxy)tetracyclo[4.2.1.1^4,7.0^2,5]deca-3-(11)-ene-10-ones, methyl-4-methylene-6-oxopentacyclo[5.4.0.0.^2,5.0^3,10.0^7,9]undecane-9-carboxylate, 3-chloromethyl-4-(carbomethoxy)tetracyclo[4.2.1.1.^3,8.0^2,5]deca-7(11)ene-10-one, 2-bromo-5-methyl-8-methylene-6-oxotricyclo[5.3.0.0^3,9]decane-4-carboxylic acid and 2-bromo-5-methyl-8-methylene-6-oxotricyclo[5.3.0.0^3,9]decane-4-methyl carboxylate, achieved through base catalyzed rearrangement, is described.     

Syntheses of Stable α-Silyloxyepoxides and α-Chloroalkyl Silyl Ethers Derivatives of 3,10-Dioxa-5-azatricyclo[5.2.1.02,6]dec-4-enes

The Diels-Alder adduct (±)-5 of furan to 1-cyanovinyl acetate was converted to (1RS,2RS,6RS,7SR,8SR,10RS)-10-{[(tert-butyl)dimethylsilyl]-oxy}-4-ethoxy (1) and -4-phenyl-3,9,11-trioxa-5-azatetracyclo[5.3.1.0^2,6.0^8,10]-undec-4-ene (2). These compounds reacted with TiCl₄ to afford stable (1RS,2RS,6RS,7SR,8SR,9SR)-9-{[(tert-butyl)dimethylsilyl]oxy}-9-chloro-4-ethoxy-3,10-dioxa-5-azatricyclo[5.2.1.0^2,6]decan-8-ol (3) and (1RS,2RS,6RS,7SR,8SR,9SR)-9-{[(tert-butyl)dimethylsilyl]oxy}-9-chloro-4-phenyl-3,10-dioxa-5-azatricyclo[5.2.1.0^2,6]decan-8-ol (4), respectively.     

Molecular and crystal structure of 2,3,4,5,6,7,8-heptachloro-2-morpholinocarbonyltricyclo[4.3.0.01,3]nona-4,7-dien-9-one

2,3,4,5,6,7,8-Heptachloro-2-morpholinocarbonyltricyclo[4.3.0.0^1,3]nona-4,7-dien-9-one was synthesized by the reaction of the tetrachlorocyclopentadienone dimer with morpholine, and its crystal and molecular structure was established by X-ray diffraction analysis.     

Chemical synthesis with metal Atoms. Cyclodimerization of norbornadiene via nickela-cyclopentane intermediates.

The catalytic cyclodimerization of norbornadiene by reaction with nickel atoms has been re-investigated. Nickela-cyclopentane derivatives are formed in the presence of α,α′-dipyridyl, α,α′-dipyridyl-exo-trans-endo-3-nickela-pentacyclo[9.2.1.1^5,8 0^2,10.0^4,9]-pentadeca-6,12-diene being the major component. By contrast, the catalytic dimerization leads predominantly to the exo-trans-exo isomer of pentacyclo[8.2.1.1^4,7.0^2,9.0^3,8] tetradeca-5,11-diene. A norbornadiene cyclotrimer of exo-trans-exo-trans-exo structure is subsequently formed.     

Molecular structure and hydrolytic stability amidinium salts derived from triazatricyclo[5.2.1.0]decane

Five amidinium salts have been prepared from triazatricyclo[5.2.1.0^4,10]decane (tacnoa) and characterised by mass spectrometry, NMR spectroscopy and X-ray crystallography. The X-ray structures revealed a long distance between the methine carbon and the ammonium nitrogen, viz., C-N distance 1.64-1.70 Å, cf. other C-N distances of 1.40-1.50 Å. An NMR study of 1-ethyl-4,7-diaza-1-azoniatricyclo[5.2.1.0^4,10]decane and 1-benzyl-4,7-diaza-1-azoniatricyclo[5.2.1.0^4,10]decane, confirmed that these amidinium salts hydrolyse in aqueous solution, the latter 60 times faster than the former. Tacnoa, which has C-N distances typical of single bonds, showed no evidence of hydrolysis after several days at 80 °C. Molecular modeling calculations indicate that the preferred gas phase structure of the salts is one where the positive charge is delocalised over the two secondary amines and the methine carbon. The calculated distance between this carbon and the ammonium nitrogen is 0.15-0.4 Å longer than in the crystal structure. The energy difference between the preferred gas phase and solid state conformations is 2 kJ mol⁻¹ and presents little barrier to nucleophilic attack of the methine carbon. Further analysis of the methine carbon geometry (C(7)) reveals that the bond angles in the benzyl salt are closer to those expected for an sp² centre than in the ethyl salt and that this could be the origin of the faster hydrolysis rate.     

Dipolar Cycloaddition of Carbonyl Ylides Generated from Methyl cis-2-Diazoacetyl-1-cyclopropanecarboxylates

Carbonyl ylide generated from methyl cis-3-diazoacetyl-2,2-diphenyl-1-cyclopropanecarboxylate in the presence of Rh₂(OAc)₄ when brought into reaction of 1,3-dipolar cycloadditionя with N-arylmaleimides afforded substituted 4-aryl-7-methoxy-9,9-diphenyl-12-oxa-4-azatetracyclo-[5.4.1.0^2,6.0^8,10]dodecene-3,5,11-triones. Concurrent processes resulted in formation of cycloheptatrienes, hydroxyacetylcyclopropanecarboxylates, and benzophenone. Carbonyl ylide generated from methyl cis-2-diazoacetyl-1-cyclopropanecarboxylate in the same reaction gave rise to exo- and endo-4-aryl-7-methoxy-12-oxa-4-azatetracyclo[5.4.1.0^2,6 .0^8,10] dodecene-3,5,11-triones.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 205–213.Original Russian Text Copyright © 2005 by Molchanov, Diev, Kopf, Kostikov.     

An efficient synthesis of pentacyclo[4.2.0.02,5.03,8.04,7]octane-1,4-dicarboxylates

Dialkyl pentacyclo[4.2.0.0^2,5.0^3,8.0^4,7]octane-1,4-dicarboxylates (where alkyl is methyl,iso-propyl, 2-fluoro-2,2-dinitroethyl, or 2,2,2-trinitroethyl) were prepared in high yields by O-alkylation of 1,4-cubanedicarboxylic acid with the corresponding monoalkyl sulfates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 801–802, April, 1993.     

Functionalization of Cubanes and Homocubanes via Oxidative Displacement of Iodine Using Hypervalent Iodine

The iodo group in 4-iodo-1-carbomethoxycubane (1) can be replaced by mesyloxy, tosyloxy and chloro by oxidative displacement with C₆H₅I(OH)OMs, C₆H₅I(OH)OTs and C₆H₅ICl₂, respectively. Similarly, the iodo group in the homocubyl compound 4-iodo-1-bromopentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonane-9-one ethylene acetal (2) was analogously replaced by mesyloxy, tosyloxy and chloro. Possible pathways for these reactions are discussed.     

Heteroleptic platinum(II) and palladium(II) complexes with thiacrown and diimine ligands

We wish to report the synthesis, crystal structures, spectroscopic and electrochemical properties of several new Pt(II) heteroleptic complexes containing the thiacrown, 9S3 (1,4,7-trithiacyclononane) with a series of substituted phenanthroline ligands and related diimine systems. These five ligands are 5,6-dimethyl-1,10-phenanthroline(5,6-Me₂-phen), 4,7-dimethyl-1,10-phenanthroline(4,7-Me₂-phen), 4,7-diphenyl-1,10-phenanthroline(4,7-Ph₂-phen), 2,2′-bipyrimidine(bpm), and pyrazino[2,3-f]quinoxaline or 1,4,5,8-tetraazaphenanthrene(tap). All complexes have the general formula [Pt(9S3)(N₂)](PF₆)₂ (N₂ = diimine ligand) and form similar structures in which the Pt(II) center is surrounded by a cis arrangement of the two N donors from the diimine chelate and two sulfur atoms from the 9S3 ligand. The third 9S3 sulfur in each structure forms a longer interaction with the platinum resulting in an elongated square pyramidal structure, and this distance is sensitive to the identity of the diimine ligand. In addition, we report the synthesis, structural, electrochemical, and spectroscopic properties of related Pd(II) 9S3 complex with tap. The ¹⁹⁵Pt NMR chemical shifts for the six Pt(II) complexes show a value near −3290 ppm, consistent with a cis-PtS₂N₂ coordination sphere although more electron-withdrawing ligands such as tap show resonances shifted by almost 100 ppm downfield. The physicochemical properties of the complexes generally follow the electron-donating or withdrawing properties of the phenanthroline substituents.     

A Comvewiemt Synthesis of 1-Aminopolycycloalkames and Their Tosylate Salts

Syntheses of oridgehead 4-amino-l-bromopentacy-clo[4.3.0.0^2.5 O^3,8.O^4,7]nonan-9-one ethyl ene acetal (6), 4-iodocubyl-l-ammonium tosylate (8) and 1-adamantane ammonium tosylate (10) are described.     

The preparation and properties of cage polycyclic systems—III: The cleavage in alkaline conditions of acetals derived from pentacyclo[5.3.0.02,5.03,9.04,8]decane and pentacyclo[4.3.0.02,5.03,8.04,7]nonane systems

The synthesis of some acetals derived from pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decane is described. The reductive cleavage of an ethylenedioxy group

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and a dimethoxy group

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in pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decane and pentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonane systems to give the methylene group is shown to occur in alkaline conditions in the presence of hydrazine. Evidence is presented for a mechanism which involves initial cleavage of the acetal by alkali to form the ketone. The substitution of a Br atom in the position neighbouring the CO group of 5-bromo-6,6-ethylenedioxypentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decan-10-one facilitates the Wolff-Kishner reaction to such an extent that hydrazine hydrate is a sufficiently strong base to induce the decomposition of the hydrazone directly.     

Photochemistry of azole N-oxides. Facile photoisomerisation of 2H-imidazole N-oxides to 1,3-diaza-6-oxabicyclo[3.1.0]hex-3-enes and synthesis of a 1,3-diaza-4,7-dioxatricyclo[4.1.0.1,603,5]heptane

Ultraviolet irradiation of a series of 2H-imidazole N-oxides 2 has been shown to effect a clean isomerisation to derivatives of the new ring system, 1,3-diaza-6-oxabicyclo[3.1.0]hex-3-ene, 7 . Epoxidation of a representative 7 has given access to the hitherto inaccessible trans-fused 1,3-diaza-4,7-dioxatricyclo[4.1.0. ^1,60^3,5]-heptane ring system 9 .