A range of sulfur-containing amides have been fluorinated with the hypervalent iodine difluoride reagents 1, and two principal reaction pathways identified. Cephalosporin esters 2 having a heteroatom in the α-position to sulfur undergo fluorination in DCM with cleavage of the carbon–sulfur bond to form novel fluorinated β-lactams 4. Sulfides with electron-withdrawing groups in the α-position undergo α-fluorination in a process analogous to the classical Pummerer reaction. This Fluoro-Pummerer reaction has been exemplified for a range of simple α-phenylsulfanylacetamides 14–19. When β-hydrogens are present in the substrate a different route is followed, with deprotonation by basic fluoride taking place to yield vinyl sulfides 41–43. When an excess of the fluorinating reagent is used these vinyl sulfides can undergo further reaction in a novel tandem Pummerer-Additive-Pummerer process to yield α,β-difluoro sulfides 45–47.
{"title":"Fluorination of sulfanyl amides using difluoroiodoarene reagents","authors":"W. Motherwell, M. Greaney, J. Edmunds, J. Steed","doi":"10.1039/B209078C","DOIUrl":"https://doi.org/10.1039/B209078C","url":null,"abstract":"A range of sulfur-containing amides have been fluorinated with the hypervalent iodine difluoride reagents 1, and two principal reaction pathways identified. Cephalosporin esters 2 having a heteroatom in the α-position to sulfur undergo fluorination in DCM with cleavage of the carbon–sulfur bond to form novel fluorinated β-lactams 4. Sulfides with electron-withdrawing groups in the α-position undergo α-fluorination in a process analogous to the classical Pummerer reaction. This Fluoro-Pummerer reaction has been exemplified for a range of simple α-phenylsulfanylacetamides 14–19. When β-hydrogens are present in the substrate a different route is followed, with deprotonation by basic fluoride taking place to yield vinyl sulfides 41–43. When an excess of the fluorinating reagent is used these vinyl sulfides can undergo further reaction in a novel tandem Pummerer-Additive-Pummerer process to yield α,β-difluoro sulfides 45–47.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"29 1","pages":"2816-2826"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83561213","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}
Y. Yamano, Yasuko Watanabe, N. Watanabe, Masayoshi Ito
A stereocontrolled synthesis of optically active β-D-glucopyranosides 7–10 and 11–14, glucosidic damascenone precursors, was accomplished utilizing an asymmetric transfer hydrogenation to α,β-acetylenic ketones catalyzed by chiral ruthenium complexes as the key step.
以手性钌配合物催化α，β-乙酰基酮的不对称转移氢化反应为关键步骤，完成了立体控制合成具有光学活性的β- d -葡萄糖吡喃苷7-10和11-14糖苷达马酮前体。
{"title":"Stereocontrolled synthesis of glucosidic damascenone precursors","authors":"Y. Yamano, Yasuko Watanabe, N. Watanabe, Masayoshi Ito","doi":"10.1039/B208758H","DOIUrl":"https://doi.org/10.1039/B208758H","url":null,"abstract":"A stereocontrolled synthesis of optically active β-D-glucopyranosides 7–10 and 11–14, glucosidic damascenone precursors, was accomplished utilizing an asymmetric transfer hydrogenation to α,β-acetylenic ketones catalyzed by chiral ruthenium complexes as the key step.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"14 1","pages":"2833-2844"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74418916","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}
{"title":"Titanium reagents for the alkylidenation of carboxylic acid and carbonic acid derivatives","authors":"R. Hartley, G. J. McKiernan","doi":"10.1039/B009709H","DOIUrl":"https://doi.org/10.1039/B009709H","url":null,"abstract":"","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"13 1","pages":"2763-2793"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81709787","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}
Nonactic acid 1 has been synthesized in 12 steps from readily available (S)-(−)-ethyl lactate in 20% overall yield. The key (“NARC”) sequence in this method involved anti-aldol addition of acylsultam 3 with aldehyde 4 followed by intramolecular oxymercuration. The efficiency and selectivity of the anti-aldol reaction was found to be critically dependent upon the ratio of Lewis acid to base. The intramolecular oxymercuration was also found to be highly diastereoselective and was attributed to allylic control consistent with previous studies in our group.
{"title":"A nucleophilic addition ring closure [NARC]-based synthesis of (+) -nonactic acid","authors":"Benjamin H. Fraser, P. Perlmutter","doi":"10.1039/B206656D","DOIUrl":"https://doi.org/10.1039/B206656D","url":null,"abstract":"Nonactic acid 1 has been synthesized in 12 steps from readily available (S)-(−)-ethyl lactate in 20% overall yield. The key (“NARC”) sequence in this method involved anti-aldol addition of acylsultam 3 with aldehyde 4 followed by intramolecular oxymercuration. The efficiency and selectivity of the anti-aldol reaction was found to be critically dependent upon the ratio of Lewis acid to base. The intramolecular oxymercuration was also found to be highly diastereoselective and was attributed to allylic control consistent with previous studies in our group.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"107 1","pages":"2896-2899"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85572047","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}
G. Grogan, Alexis Carstairs, I. Jackson, D. McIntyre, A. Watt, S. Flitsch, N. Turner
Perkin 1 Abstracts: Biocatalysis in Organic Synthesis aims to cover recent literature concerning the applications of enzymes and micro-organisms as catalysts in organic synthesis. The abstracts will emphasise the key synthetic step(s) that are mediated by the biocatalyst. Emerging technologies for biocatalyst design and optimisation will also be included.
{"title":"Perkin 1 Abstracts: Biocatalysis in Organic Synthesis","authors":"G. Grogan, Alexis Carstairs, I. Jackson, D. McIntyre, A. Watt, S. Flitsch, N. Turner","doi":"10.1039/B211566M","DOIUrl":"https://doi.org/10.1039/B211566M","url":null,"abstract":"Perkin 1 Abstracts: Biocatalysis in Organic Synthesis aims to cover recent literature concerning the applications of enzymes and micro-organisms as catalysts in organic synthesis. The abstracts will emphasise the key synthetic step(s) that are mediated by the biocatalyst. Emerging technologies for biocatalyst design and optimisation will also be included.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"14 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79791302","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}
In situ IR and multinuclear NMR are used to monitor the formation of protonated diacetylketene tetrachloroaluminate (1) in the reaction of acetyl chloride and AlCl3 in both dichloromethane and in 1-butyl-3-methylimidazolium chloride ([bmim]Cl). The existence of a fast equilibrium between two enolic forms of protonated diacetylketene (with [AlCl4]− as the counterion) is established. The structure of 1 is determined by the rarely used 13C{1H}–13C{1H} COSY experiment.
{"title":"In situ IR and NMR spectroscopic investigation of the formation and structure of protonated diacetylketene tetrachloroaluminate","authors":"S. Csihony, A. Bodor, J. Rohonczy, I. Horváth","doi":"10.1039/B208387F","DOIUrl":"https://doi.org/10.1039/B208387F","url":null,"abstract":"In situ IR and multinuclear NMR are used to monitor the formation of protonated diacetylketene tetrachloroaluminate (1) in the reaction of acetyl chloride and AlCl3 in both dichloromethane and in 1-butyl-3-methylimidazolium chloride ([bmim]Cl). The existence of a fast equilibrium between two enolic forms of protonated diacetylketene (with [AlCl4]− as the counterion) is established. The structure of 1 is determined by the rarely used 13C{1H}–13C{1H} COSY experiment.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"10 2","pages":"2861-2865"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72553223","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 novel tri(propylene glycol) glycerolate diacrylate cross-linked polystyrene support for solid phase peptide synthesis was prepared by aqueous radical suspension polymerization. The peptides were grown from the hydroxy functionality of the cross-linker in the polymer and this makes it unique among other styrene-based polymer supports that are currently used in polypeptide synthesis. The role of the polymer support in peptide synthesis was established by studies delineating the optimization of synthetic steps involved in solid phase synthesis. The optimization studies include C-terminal amino acid incorporation, Nα-Fmoc and Boc-deprotection, acylation reactions and the removal of the target peptide from the support. The dependence between the nature and extent of cross-linking of the polymer backbone and the reactivity of the attached amino groups was investigated by carrying out a reactivity study on amide bond formation compared with Merrifield resin. The resin-like behavior of the new support was studied by synthesizing a ‘difficult’ sequence of the (34–42) fragment of β-amyloid peptide (1–42) and compared with commercially available Merrifield and Sheppard resins. The synthetic utility of the support was established by synthesizing a 23-residue NR 2B peptide substrate of Ca2+/calmodulin binding peptide in high yield and purity. Better solvation of the resin beads, enhanced coupling efficiency in the peptide synthetic steps and the high yield and purity of the peptides synthesized highlights the positive role of the cross-linker in the new polystyrene support.
{"title":"Synthesis and optimization of tri(propylene glycol) glycerolate diacrylate cross-linked polystyrene resin in polypeptide synthesis: role of the macromolecular support in solid phase peptide synthesis","authors":"P. Sasikumar, K. S. Kumar, C. Arunan, V. Pillai","doi":"10.1039/B206879F","DOIUrl":"https://doi.org/10.1039/B206879F","url":null,"abstract":"A novel tri(propylene glycol) glycerolate diacrylate cross-linked polystyrene support for solid phase peptide synthesis was prepared by aqueous radical suspension polymerization. The peptides were grown from the hydroxy functionality of the cross-linker in the polymer and this makes it unique among other styrene-based polymer supports that are currently used in polypeptide synthesis. The role of the polymer support in peptide synthesis was established by studies delineating the optimization of synthetic steps involved in solid phase synthesis. The optimization studies include C-terminal amino acid incorporation, Nα-Fmoc and Boc-deprotection, acylation reactions and the removal of the target peptide from the support. The dependence between the nature and extent of cross-linking of the polymer backbone and the reactivity of the attached amino groups was investigated by carrying out a reactivity study on amide bond formation compared with Merrifield resin. The resin-like behavior of the new support was studied by synthesizing a ‘difficult’ sequence of the (34–42) fragment of β-amyloid peptide (1–42) and compared with commercially available Merrifield and Sheppard resins. The synthetic utility of the support was established by synthesizing a 23-residue NR 2B peptide substrate of Ca2+/calmodulin binding peptide in high yield and purity. Better solvation of the resin beads, enhanced coupling efficiency in the peptide synthetic steps and the high yield and purity of the peptides synthesized highlights the positive role of the cross-linker in the new polystyrene support.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"26 1","pages":"2886-2895"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74939522","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 simple, effective procedure for the preparation of 4-nitroalkanoates 6–9 by the Michael reaction of nitroalkanes 2–5 with the acrylate 1 is described. The primary nitro adduct 6 undergoes isomerization to hydroxamic acid 10 while heated in boiling nitromethane. Consecutive reactions of the latter compound lead to the formation of N-hydroxysuccinimide 11 and its N-ethoxy derivative 12. The spontaneous Nef reaction of the mother 4-nitrobutanoic acid 15 gives N-hydroxysuccinimide 14. The analogous reaction of secondary nitroalkanoic acids 16 and 17 provides 4-oxoalkanoic acids 18 and 19, respectively. Intramolecular participation by the carboxylic acid group in the Nef reaction is proposed.
{"title":"Nitroalkanes as nucleophiles in a self-catalytic Michael reaction","authors":"H. Krawczyk, W. Wolf, M. Sliwinski","doi":"10.1039/B209302M","DOIUrl":"https://doi.org/10.1039/B209302M","url":null,"abstract":"A simple, effective procedure for the preparation of 4-nitroalkanoates 6–9 by the Michael reaction of nitroalkanes 2–5 with the acrylate 1 is described. The primary nitro adduct 6 undergoes isomerization to hydroxamic acid 10 while heated in boiling nitromethane. Consecutive reactions of the latter compound lead to the formation of N-hydroxysuccinimide 11 and its N-ethoxy derivative 12. The spontaneous Nef reaction of the mother 4-nitrobutanoic acid 15 gives N-hydroxysuccinimide 14. The analogous reaction of secondary nitroalkanoic acids 16 and 17 provides 4-oxoalkanoic acids 18 and 19, respectively. Intramolecular participation by the carboxylic acid group in the Nef reaction is proposed.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"7 1","pages":"2794-2798"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74167172","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}
Both γ-irradiation and Fenton reaction generate oxidising species that damage isolated DNA. The comparison of the distribution of oxidised bases suggested that the Fenton reaction produces hydroxyl radicals like ionizing radiation. However, the former process was also found to generate a reducing species that increased the yield of formamidopyrimidine derivatives at the expense of the 8-oxo compounds of purine bases. Another peculiarity of the Fenton reaction was its ability to induce the formation, though in very low yield, of the malonaldehyde-2′-deoxyguanosine adduct in DNA, likely via the formation of base propenals upon degradation of the 2-deoxyribose unit.
{"title":"Comparative study of base damage induced by gamma radiation and Fenton reaction in isolated DNA","authors":"S. Frelon, T. Douki, A. Favier, J. Cadet","doi":"10.1039/B207532F","DOIUrl":"https://doi.org/10.1039/B207532F","url":null,"abstract":"Both γ-irradiation and Fenton reaction generate oxidising species that damage isolated DNA. The comparison of the distribution of oxidised bases suggested that the Fenton reaction produces hydroxyl radicals like ionizing radiation. However, the former process was also found to generate a reducing species that increased the yield of formamidopyrimidine derivatives at the expense of the 8-oxo compounds of purine bases. Another peculiarity of the Fenton reaction was its ability to induce the formation, though in very low yield, of the malonaldehyde-2′-deoxyguanosine adduct in DNA, likely via the formation of base propenals upon degradation of the 2-deoxyribose unit.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"78 5 1","pages":"2866-2870"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79644168","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}
Jun Lu, Xuenong Xu, Shaozhong Wang, Cunde Wang, Yuefei Hu, Hongwen Hu
A novel route for the preparation of non-racemic 1-[α-(1-azacycloalkyl)benzyl]-2-naphthols was developed, which involves regioselective N-cycloalkylation of the Betti base with dials in the presence of NaBH3CN to give 1-azacycloalka[2,1-b]oxazine followed by the selective cleavage of a C–O bond with LiAlH4. As a new family of chiral ligands, their application in the enantioselective addition of diethylzinc to aryl aldehydes was tested. The ligands incorporating pyrrolidine and piperidine led to highly efficient asymmetric induction to give products in up to 96% yield and 99% ee.
{"title":"Novel preparation of non-racemic 1-[α-(1-azacycloalkyl)benzyl]-2-naphthols from Betti base and their application as chiral ligands in the asymmetric addition of diethylzinc to aryl aldehydes","authors":"Jun Lu, Xuenong Xu, Shaozhong Wang, Cunde Wang, Yuefei Hu, Hongwen Hu","doi":"10.1039/B204534F","DOIUrl":"https://doi.org/10.1039/B204534F","url":null,"abstract":"A novel route for the preparation of non-racemic 1-[α-(1-azacycloalkyl)benzyl]-2-naphthols was developed, which involves regioselective N-cycloalkylation of the Betti base with dials in the presence of NaBH3CN to give 1-azacycloalka[2,1-b]oxazine followed by the selective cleavage of a C–O bond with LiAlH4. As a new family of chiral ligands, their application in the enantioselective addition of diethylzinc to aryl aldehydes was tested. The ligands incorporating pyrrolidine and piperidine led to highly efficient asymmetric induction to give products in up to 96% yield and 99% ee.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"18 1","pages":"2900-2903"},"PeriodicalIF":0.0,"publicationDate":"2002-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89102197","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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