The Bischler–Napieralski reaction, which is used to prepare dihydroisoquinolines from phenylethylamides, is demonstrated by the reaction of (S)-1-alkyl-1,2-diphenylethylamides with POCl3–P2O5. The reaction generated 3-alkyl-4-phenyl-1,2-dihydroisoquinolines with stereochemical selectivities of 80–91% de depending on the alkyl and the acetamide substituents. These are the first examples of the asymmetric Bischler–Napieralski reaction where cyclisation discriminates between two identical diastereotopic aryl groups. Reduction of the resultant dihydroisoquinoline products with LiAlH4 generated the corresponding 1,2,3,4-tetrahydroisoquinolines in a stereoselective manner, carrying three stereogenic centres at C(1), C(3) and C(4).
{"title":"The asymmetric Bischler–Napieralski reaction: preparation of 1,3,4-trisubstituted 1,2,3,4-tetrahydroisoquinolines","authors":"M. Nicoletti, D. O'Hagan, A. Slawin","doi":"10.1039/B106942J","DOIUrl":"https://doi.org/10.1039/B106942J","url":null,"abstract":"The Bischler–Napieralski reaction, which is used to prepare dihydroisoquinolines from phenylethylamides, is demonstrated by the reaction of (S)-1-alkyl-1,2-diphenylethylamides with POCl3–P2O5. The reaction generated 3-alkyl-4-phenyl-1,2-dihydroisoquinolines with stereochemical selectivities of 80–91% de depending on the alkyl and the acetamide substituents. These are the first examples of the asymmetric Bischler–Napieralski reaction where cyclisation discriminates between two identical diastereotopic aryl groups. Reduction of the resultant dihydroisoquinoline products with LiAlH4 generated the corresponding 1,2,3,4-tetrahydroisoquinolines in a stereoselective manner, carrying three stereogenic centres at C(1), C(3) and C(4).","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"19 1","pages":"116-121"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73227264","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}
Phthalocyanines solubilised by either 8 or 16 aryloxy or haloaryloxy groups are described. A series of phthalocyanine derivatives were prepared containing indium. 1,2-Dinitriles and the corresponding diiminoisoindolines were used as precursors. A naphthalocyanine metallated with indium and solubilised with four tert-butyl groups is reported.
{"title":"Synthesis of soluble halogenated aryloxy substituted indium phthalocyanines","authors":"M. Plater, Adam Jeremiah, G. Bourhill","doi":"10.1039/B107689M","DOIUrl":"https://doi.org/10.1039/B107689M","url":null,"abstract":"Phthalocyanines solubilised by either 8 or 16 aryloxy or haloaryloxy groups are described. A series of phthalocyanine derivatives were prepared containing indium. 1,2-Dinitriles and the corresponding diiminoisoindolines were used as precursors. A naphthalocyanine metallated with indium and solubilised with four tert-butyl groups is reported.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"43 1","pages":"91-96"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73307105","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}
K. Banert, Jens Lehmann, H. Quast, G. Meichsner, D. Regnat, B. Seiferling
Despite the great number of 4,5-dihydro-1H-1,2,3-triazoles synthesized, 15N NMR data of these heterocycles are extremely rare. The aim of this paper is to present such data and examples of their application. The compounds investigated have been synthesized according to the given references or procedures. Their 15N NMR spectra were measured at natural abundance. For some compounds, the chemical shift assignments were confirmed with the help of 15N labelled material. The influences on 15N chemical shifts of substitution pattern, solvent and concentration were investigated. Additionally, some lanthanide induced shift (LIS) investigations were performed. 13C labelled compounds were employed as tools to provide the assignment of tautomeric structures.
{"title":"15N NMR spectra, tautomerism and diastereomerism of 4,5-dihydro-1H-1,2,3-triazoles","authors":"K. Banert, Jens Lehmann, H. Quast, G. Meichsner, D. Regnat, B. Seiferling","doi":"10.1039/B107326E","DOIUrl":"https://doi.org/10.1039/B107326E","url":null,"abstract":"Despite the great number of 4,5-dihydro-1H-1,2,3-triazoles synthesized, 15N NMR data of these heterocycles are extremely rare. The aim of this paper is to present such data and examples of their application. The compounds investigated have been synthesized according to the given references or procedures. Their 15N NMR spectra were measured at natural abundance. For some compounds, the chemical shift assignments were confirmed with the help of 15N labelled material. The influences on 15N chemical shifts of substitution pattern, solvent and concentration were investigated. Additionally, some lanthanide induced shift (LIS) investigations were performed. 13C labelled compounds were employed as tools to provide the assignment of tautomeric structures.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"68 1","pages":"126-134"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84120635","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}
Alistair J. Fielding, P. Franchi, B. P. Roberts, Teika M. Smits
EPR spectroscopy and density functional theory have been applied to study the formation and subsequent β-scission of a series of dialkoxyalkyl radicals. Abstraction of hydrogen by photochemically-generated tert-butoxyl radicals from acyclic acetals R1O(R2O)CHR3, and from cyclic analogues derived from diols, takes place mainly from the acetal carbon atom to give radicals of the type R1O(R2O)ĊR3 and relative rates of abstraction have been determined in competition experiments. When R3 = phenyl or vinyl, the activating influence of these substituents on hydrogen-atom abstraction is smaller than might be expected, probably because delocalisation of the unpaired electron on to the unsaturated group comes at the expense of planarisation at Cα, in opposition to the natural pyramidalising tendency of the two α-alkoxy groups. Absolute rate constants and Arrhenius activation parameters for β-scission of R1O(R2O)ĊR3 have been determined by a steady-state EPR method and the results can be understood in terms of angle-strain and stereoelectronic effects. β-Scission of selected cyclic dialkoxyalkyl radicals that carry a phenyl or vinyl substituent at the radical centre has been investigated using density functional theory at the UB3LYP/6-31G(d,p) level. Computed activation parameters are in good agreement with the experimental results, where comparison is possible. Both experiment and theory indicate that benzylic 2-phenyl-1,3-dioxan-2-yl radicals undergo β-scission more readily than the corresponding allylic 2-vinyl-1,3-dioxan-2-yl radicals.
{"title":"EPR and computational studies of the formation and beta-scission of cyclic and acyclic dialkoxyalkyl radicals","authors":"Alistair J. Fielding, P. Franchi, B. P. Roberts, Teika M. Smits","doi":"10.1039/B106140M","DOIUrl":"https://doi.org/10.1039/B106140M","url":null,"abstract":"EPR spectroscopy and density functional theory have been applied to study the formation and subsequent β-scission of a series of dialkoxyalkyl radicals. Abstraction of hydrogen by photochemically-generated tert-butoxyl radicals from acyclic acetals R1O(R2O)CHR3, and from cyclic analogues derived from diols, takes place mainly from the acetal carbon atom to give radicals of the type R1O(R2O)ĊR3 and relative rates of abstraction have been determined in competition experiments. When R3 \u0000= phenyl or vinyl, the activating influence of these substituents on hydrogen-atom abstraction is smaller than might be expected, probably because delocalisation of the unpaired electron on to the unsaturated group comes at the expense of planarisation at Cα, in opposition to the natural pyramidalising tendency of the two α-alkoxy groups. Absolute rate constants and Arrhenius \u0000activation parameters for β-scission of R1O(R2O)ĊR3 have been determined by a steady-state EPR method and the results can be understood in terms of angle-strain and stereoelectronic effects. β-Scission of selected cyclic dialkoxyalkyl radicals that carry a phenyl or vinyl substituent at the radical centre has been investigated using density functional theory at the UB3LYP/6-31G(d,p) level. Computed activation parameters are in good agreement with the experimental results, where comparison is possible. Both experiment and theory indicate that benzylic 2-phenyl-1,3-dioxan-2-yl radicals undergo β-scission more readily than the corresponding allylic 2-vinyl-1,3-dioxan-2-yl radicals.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"9 1","pages":"155-163"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81555639","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. Keglevich, Henrietta Forintos, T. Körtvélyesi, L. Tőke,
The intermediate oxaphosphetenes 2 formed by the novel cycloaddition of the PO group of arylphosphine oxides 1 and the acetylene moiety of DMAD are stabilised by an inverse Wittig reaction to afford the corresponding stabilised phosphonium ylide 3.
{"title":"Inverse Wittig reaction of oxaphosphetenes formed by the [2+2] cycloaddition of arylphosphine oxides and dimethyl acetylenedicarboxylate (DMAD)","authors":"G. Keglevich, Henrietta Forintos, T. Körtvélyesi, L. Tőke,","doi":"10.1039/B108675H","DOIUrl":"https://doi.org/10.1039/B108675H","url":null,"abstract":"The intermediate oxaphosphetenes 2 formed by the novel cycloaddition of the PO group of arylphosphine oxides 1 and the acetylene moiety of DMAD are stabilised by an inverse Wittig reaction to afford the corresponding stabilised phosphonium ylide 3.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"34 1","pages":"26-27"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82280847","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}
Condensation of triformylmethane (TFM) with adenosine has been studied in pyridine and aqueous dioxane. One 1 ∶ 1 (2) and two 2 ∶ 1 (6 and 7) TFM–adenosine adducts were isolated. The structural assignment of these products by 1H and 13C NMR and UV spectroscopy and MS spectrometry suggested that the appearance of the 2 ∶ 1 adducts is connected to a competitive self-condensation of TFM, the stable end product of which is benzene-1,3,5-tricarbaldehyde. The intermediates on the reaction pathway can be reacted with adenosine affording a new procedure for nucleic acid base modification. The mechanisms of formation and the role of intramolecular hydrogen bonding in stabilization of cyclic adenosine adducts are discussed.
{"title":"Condensation of triformylmethane with adenosine: novel cyclic adducts derived from 1,3-dicarbonyl compounds","authors":"K. Neuvonen, N. Koissi, H. Lönnberg","doi":"10.1039/B104790F","DOIUrl":"https://doi.org/10.1039/B104790F","url":null,"abstract":"Condensation of triformylmethane (TFM) with adenosine has been studied in pyridine and aqueous dioxane. One 1 ∶ 1 (2) and two 2 ∶ 1 (6 and 7) TFM–adenosine adducts were isolated. The structural assignment of these products by 1H and 13C NMR and UV spectroscopy and MS spectrometry suggested that the appearance of the 2 ∶ 1 adducts is connected to a competitive self-condensation of TFM, the stable end product of which is benzene-1,3,5-tricarbaldehyde. The intermediates on the reaction pathway can be reacted with adenosine affording a new procedure for nucleic acid base modification. The mechanisms of formation and the role of intramolecular hydrogen bonding in stabilization of cyclic adenosine adducts are discussed.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"81 1","pages":"173-177"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81664854","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}
Highly diastereoselective reductions and organometallic additions in bicyclic lactams have been observed, which appear to result either from a stereoelectronic interaction of the pyramidalised nitrogen lone pair or from steric interactions in the bicyclic system. These products can be readily deprotected to give hydroxylated lactams.
{"title":"Diastereocontrolled synthesis of hydroxylated lactams","authors":"M. Andrews, A. Brewster, M. Moloney","doi":"10.1039/B108056N","DOIUrl":"https://doi.org/10.1039/B108056N","url":null,"abstract":"Highly diastereoselective reductions and organometallic additions in bicyclic lactams have been observed, which appear to result either from a stereoelectronic interaction of the pyramidalised nitrogen lone pair or from steric interactions in the bicyclic system. These products can be readily deprotected to give hydroxylated lactams.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"22 1","pages":"80-90"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78933582","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 very fast [1,4] carbon-to-oxygen silicon migration-rearrangement leading to O-silylated cinnamyl alcohols occurs when the carbanion generated from sulfone 1 is reacted with carbonyl compounds. The mandatory role of the adjacent phenyl ring in this process is demonstrated when compared to the behaviour of the corresponding unsubstituted sulfone 3.
{"title":"Phenyl group acceleration of [1,4] carbon-to-oxygen silicon-mediated elimination–rearrangement in β-silyl sulfones. Synthesis of O -silylated cinnamyl alcohols","authors":"S. Menichetti, C. Stirling","doi":"10.1039/B109805E","DOIUrl":"https://doi.org/10.1039/B109805E","url":null,"abstract":"A very fast [1,4] carbon-to-oxygen silicon migration-rearrangement leading to O-silylated cinnamyl alcohols occurs when the carbanion generated from sulfone 1 is reacted with carbonyl compounds. The mandatory role of the adjacent phenyl ring in this process is demonstrated when compared to the behaviour of the corresponding unsubstituted sulfone 3.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"3 1","pages":"28-30"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72695262","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}
J. Dormann, A. Ruoff, J. Schatz, M. Vysotsky, V. Böhmer
Structural models for self-assembled dimers composed of two urea calix[4]arenes which entrap benzene or cyclohexane are developed using Fourier transform infrared (FTIR) spectroscopy. Based on the host–guest ratio determined by 1H NMR spectroscopy in solution, and confirmed for the solid state by a thermogravimetric analysis, it is possible to prove by a comparison of the FTIR data of host, guest, complex and model compounds, that the capsule is held together by a cyclic array of weak and strong hydrogen bonds between the urea units attached at the wide rim of the calixarenes. The dimerization of the two urea units leads to a loss of symmetry, and an averaged C4 symmetrical arrangement is probable. Guest molecules, such as benzene or cyclohexane, are enclosed inside the container rotating fast on the IR timescale around a longitudinal axis of the guest. From the observed splitting of absorption bands upon dimerization and inclusion it follows that either two crystallographically independent types of capsules exist in the crystal lattice or that the guests are occupying two major orientations in the capsule. As indicated by a higher complexation induced shift for cyclohexane, this guest exhibits a tighter interaction with the host molecules compared to benzene.
{"title":"Vibrational spectroscopy of a tetraureidocalix[4]arene based molecular capsule","authors":"J. Dormann, A. Ruoff, J. Schatz, M. Vysotsky, V. Böhmer","doi":"10.1039/B108055P","DOIUrl":"https://doi.org/10.1039/B108055P","url":null,"abstract":"Structural models for self-assembled dimers composed of two urea calix[4]arenes which entrap benzene or cyclohexane are developed using Fourier transform infrared (FTIR) spectroscopy. Based on the host–guest ratio determined by 1H NMR spectroscopy in solution, and confirmed for the solid state by a thermogravimetric analysis, it is possible to prove by a comparison of the FTIR data of host, guest, complex and model compounds, that the capsule is held together by a cyclic array of weak and strong hydrogen bonds between the urea units attached at the wide rim of the calixarenes. The dimerization of the two urea units leads to a loss of symmetry, and an averaged C4 symmetrical arrangement is probable. Guest molecules, such as benzene or cyclohexane, are enclosed inside the container rotating fast on the IR timescale around a longitudinal axis of the guest. From the observed splitting of absorption bands upon dimerization and inclusion \u0000it follows that either two crystallographically independent types of capsules exist in the crystal lattice or that the guests are occupying two major orientations in the capsule. As indicated by a higher complexation induced shift for cyclohexane, this guest exhibits a tighter interaction with the host molecules compared to benzene.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"4 1","pages":"83-87"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87644734","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}
Synthetic and spectroscopic details relating to a set of heteroaromatic N-benzyl carboxamides and in particular the corresponding tert-butyl acylcarbamates are reported. These compounds were required to study the postulated effect of various heterocycles (pyridine and pyrazine with and without condensed benzene rings) on the cleavage of acyl–N bonds by reduction. All compounds were initially characterized by cyclic voltammetry (CV) which indicated various degrees of facilitated reduction, reflecting a direct influence of the heterocyclic component. Selected acylcarbamates were studied with respect to acyl–N bond cleavage by mild reducing agents, and selectively deacylated by activated aluminium and sodium borohydride. Conversion to acylcarbamates followed by reduction might therefore be a mild, efficient two-step procedure to effect cleavage of amides, allowing isolation of carbamates and with sodium borohydride also the corresponding alcohols.
{"title":"Reductive cleavage of N-substituted aromatic amides as tert-butyl acylcarbamates","authors":"U. Ragnarsson, L. Grehn, H. Maia, L. Monteiro","doi":"10.1039/B107330N","DOIUrl":"https://doi.org/10.1039/B107330N","url":null,"abstract":"Synthetic and spectroscopic details relating to a set of heteroaromatic N-benzyl carboxamides and in particular the corresponding tert-butyl acylcarbamates are reported. These compounds were required to study the postulated effect of various heterocycles (pyridine and pyrazine with and without condensed benzene rings) on the cleavage of acyl–N bonds by reduction. All compounds were initially characterized by cyclic voltammetry (CV) which indicated various degrees of facilitated reduction, reflecting a direct influence of the heterocyclic component. Selected acylcarbamates were studied with respect to acyl–N bond cleavage by mild reducing agents, and selectively deacylated by activated aluminium and sodium borohydride. Conversion to acylcarbamates followed by reduction might therefore be a mild, efficient two-step procedure to effect cleavage of amides, allowing isolation of carbamates and with sodium borohydride also the corresponding \u0000alcohols.","PeriodicalId":17267,"journal":{"name":"Journal of The Chemical Society-perkin Transactions 1","volume":"59 1","pages":"97-101"},"PeriodicalIF":0.0,"publicationDate":"2002-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84717335","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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