Thermal or silver-ion induced electrocyclic ring-opening of Cyclohexannulated [5.3.1]propellanes such as 7 and 8 provides ABC ring analogues of paclitaxel (taxol) including compounds 10, 11 and 14.
{"title":"Cyclohexannulated [5.3.1]propellanes as precursors to the ABC ring system of paclitaxel (taxolTM)","authors":"M. Banwell, R. Gable, S. Peters, J. R. Phyland","doi":"10.1039/C39950001395","DOIUrl":"https://doi.org/10.1039/C39950001395","url":null,"abstract":"Thermal or silver-ion induced electrocyclic ring-opening of Cyclohexannulated [5.3.1]propellanes such as 7 and 8 provides ABC ring analogues of paclitaxel (taxol) including compounds 10, 11 and 14.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74291167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The recent suggestion, based on gas-phase experimental data, that the most stable isomer of protonated benzene has a face-protonated π-complex structure is not supported by our detailed computations which indicate that the π-complex is a second-order saddle point on the potential energy surface, lying 199 kJ mo–1 higher in energy than the well-established C2vσ-protonated structure.
{"title":"Is the most stable gas-phase isomer of the benzenium cation a face-protonated π-complex?","authors":"M. Glukhovtsev, A. Pross, A. Nicolaides, L. Radom","doi":"10.1039/C39950002347","DOIUrl":"https://doi.org/10.1039/C39950002347","url":null,"abstract":"The recent suggestion, based on gas-phase experimental data, that the most stable isomer of protonated benzene has a face-protonated π-complex structure is not supported by our detailed computations which indicate that the π-complex is a second-order saddle point on the potential energy surface, lying 199 kJ mo–1 higher in energy than the well-established C2vσ-protonated structure.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74763720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Incorporation of titanium into the framework of zeolite beta was achieved by simply treating Al-β zeolite with an ammonium titanyl oxalate solution followed by air calcinations; the material obtained is a very active catalyst for the epoxidation of olefins.
{"title":"A new and simple method for the preparation of active Ti-β zeolite catalysts","authors":"J. S. Reddy, A. Sayari","doi":"10.1039/C39950000023","DOIUrl":"https://doi.org/10.1039/C39950000023","url":null,"abstract":"Incorporation of titanium into the framework of zeolite beta was achieved by simply treating Al-β zeolite with an ammonium titanyl oxalate solution followed by air calcinations; the material obtained is a very active catalyst for the epoxidation of olefins.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74821155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Bravo, F. Fontana, G. Fronza, A. Mele, F. Minisci
The oxidation of alkanes by dimethyldioxirane is dramatically affected by the presence of molecular oxygen and radical inhibitors, supporting the hypothesis of a free-radical mechanism for these extraordinarily selective reactions; the factors affecting the free-radical selectivity are suggested.
{"title":"Induced homolysis of dimethyldioxirane by alkanes and alkyl radicals in oxidation processes. The dramatic role of molecular oxygen and radical inhibitors","authors":"A. Bravo, F. Fontana, G. Fronza, A. Mele, F. Minisci","doi":"10.1039/C39950001573","DOIUrl":"https://doi.org/10.1039/C39950001573","url":null,"abstract":"The oxidation of alkanes by dimethyldioxirane is dramatically affected by the presence of molecular oxygen and radical inhibitors, supporting the hypothesis of a free-radical mechanism for these extraordinarily selective reactions; the factors affecting the free-radical selectivity are suggested.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74828490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bis(2,6-di-tert-butyl-4-methylphenoxy)isobutylaluminium reacts with dirhenium heptoxide to give complexes containing aluminium coordinated with perrhenate and 2,6-di-tert-butyl-4-methylphenoxy ligands which are active new catalysts for the metathesis of alkenes.
{"title":"New homogeneous rhenium-based metathesis catalysts as models of the rhenium on alumina heterogeneous catalyst","authors":"D. Commereuc","doi":"10.1039/C39950000791","DOIUrl":"https://doi.org/10.1039/C39950000791","url":null,"abstract":"Bis(2,6-di-tert-butyl-4-methylphenoxy)isobutylaluminium reacts with dirhenium heptoxide to give complexes containing aluminium coordinated with perrhenate and 2,6-di-tert-butyl-4-methylphenoxy ligands which are active new catalysts for the metathesis of alkenes.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78705608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The reaction between vinyldiphenylphosphine and [{(η5-C5Me5)RhCl2}2] proceeds via an intramolecular hydroalkyl addition to yield the two isomeric products 1aand 2a.
{"title":"Novel intramolecular Michael-type reactions between vinyldiphenylphosphine and pentamethylcyclopentadienyl coordinated to rhodium(III): formation and X-ray structures of heptadentate 10-electron donor ligands","authors":"L. Barthel-Rosa, V. Catalano, J. H. Nelson","doi":"10.1039/C39950001629","DOIUrl":"https://doi.org/10.1039/C39950001629","url":null,"abstract":"The reaction between vinyldiphenylphosphine and [{(η5-C5Me5)RhCl2}2] proceeds via an intramolecular hydroalkyl addition to yield the two isomeric products 1aand 2a.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76115580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Masciocchi, M. Moret, A. Sironi, G. Ardizzoia, S. Cenini, G. L. Monica
[{Pd(dmpz)2(Hdmpz)2}2](Hdmpz = 3,5-dimethylpyrazole) reacts with COS, both in solution and in the solid state, affording [Pd{SC(O)dmpz}2] and [{Pd(dmpz)2(Hdmpz)2}2]mdot;COS, respectively; the structure of the latter is determined by ab initio methods from conventional X-ray powder diffraction data only.
{"title":"COS trapping by palladium pyrazolates: addition vs. clathration","authors":"N. Masciocchi, M. Moret, A. Sironi, G. Ardizzoia, S. Cenini, G. L. Monica","doi":"10.1039/C39950001955","DOIUrl":"https://doi.org/10.1039/C39950001955","url":null,"abstract":"[{Pd(dmpz)2(Hdmpz)2}2](Hdmpz = 3,5-dimethylpyrazole) reacts with COS, both in solution and in the solid state, affording [Pd{SC(O)dmpz}2] and [{Pd(dmpz)2(Hdmpz)2}2]mdot;COS, respectively; the structure of the latter is determined by ab initio methods from conventional X-ray powder diffraction data only.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74946871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A broad substrate specificity for adenosine 5′-diphosphate ribosyl cyclase is demonstrated by cyclisation of ribose-and purine-modified nicotinamide adenine dinucleotide analogues to mimics of cyclic adenosine 5′-diphosphate ribose, generating a straightforward route for structural modification of this important Ca2+-mobilising nucleotide.
{"title":"Chemoenzymatic synthesis of analogues of the second messenger candidate cyclic adenosine 5′-diphosphate ribose","authors":"G. A. Ashamu, A. Galione, B. Potter","doi":"10.1039/C39950001359","DOIUrl":"https://doi.org/10.1039/C39950001359","url":null,"abstract":"A broad substrate specificity for adenosine 5′-diphosphate ribosyl cyclase is demonstrated by cyclisation of ribose-and purine-modified nicotinamide adenine dinucleotide analogues to mimics of cyclic adenosine 5′-diphosphate ribose, generating a straightforward route for structural modification of this important Ca2+-mobilising nucleotide.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76480511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The triplet and singlet state properties of the title compound are reported: nitroxyl free radicals and oxygen enhance the triplet yield significantly; electron transfer from the singlet excited state to methyl viologen in acetonitrile produced the corresponding free radicals which recombine with second-order kinetics.
{"title":"Excited state electron and energy transfer of a highly fluorescent heterocyclic dye: a laser flash photolysis study of 2,5-dimethyl-3,6-diphenylpyrrolo[3,4-c]pyrrole-1,4-dione","authors":"V. Srivatsavoy, M. Eschle, J. Moser, M. Grätzel","doi":"10.1039/C39950000303","DOIUrl":"https://doi.org/10.1039/C39950000303","url":null,"abstract":"The triplet and singlet state properties of the title compound are reported: nitroxyl free radicals and oxygen enhance the triplet yield significantly; electron transfer from the singlet excited state to methyl viologen in acetonitrile produced the corresponding free radicals which recombine with second-order kinetics.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76585541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. D. L. Rios, M. J. Tenorio, M. Puerta, P. Valerga
The complex [(C5Me5)RuCl(dippe)](dippe = l,2-bis(diisopropylphosphino)ethane) reacts with alk-1-ynes in MeOH in the presence of NaBPh4 yielding the metastable hydrido-alkynyl derivatives [(C5Me5)Ru(H)(CCR)(dippe)][BPh4](R = CO2Me, SiMe3 or Ph), intermediates in the formation of the corresponding vinylidene complexes, to which these compounds rearrange both in solution and in the solid state.
{"title":"Irreversible rearrangement of half-sandwich ruthenium hydrido-alkynyl complexes to their vinylidene isomers","authors":"I. D. L. Rios, M. J. Tenorio, M. Puerta, P. Valerga","doi":"10.1039/C39950001757","DOIUrl":"https://doi.org/10.1039/C39950001757","url":null,"abstract":"The complex [(C5Me5)RuCl(dippe)](dippe = l,2-bis(diisopropylphosphino)ethane) reacts with alk-1-ynes in MeOH in the presence of NaBPh4 yielding the metastable hydrido-alkynyl derivatives [(C5Me5)Ru(H)(CCR)(dippe)][BPh4](R = CO2Me, SiMe3 or Ph), intermediates in the formation of the corresponding vinylidene complexes, to which these compounds rearrange both in solution and in the solid state.","PeriodicalId":17282,"journal":{"name":"Journal of The Chemical Society, Chemical Communications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77415794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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