Glycosylation reaction is one of the important aspects of carbohydrate chemistry, where two different units are frequently linked through the C-O bonds. In the pursuit of advancing this field, the design and development of sustainable catalytic methods for O-glycosylation, which can provide an alternate and effective tool to traditional protocols involving stoichiometric promoters and classical donors are considered as highly challenging yet important facets of glycochemistry. Herein, we report a simple and efficient Fe(III)-catalyzed method for O-glycosylation through the activation of bifunctional phenylpropiolate glycoside (PPG) donors. This mild and effective method involves the use of inexpensive, and less-toxic FeCl3 as a catalyst and easily synthesizable, benchtop stable glycosyl ester-based PPG donors, which react with various sugar as well as non-sugar-based acceptors to deliver the corresponding O-glycosides in good yields with moderate anomeric selectivity along with regeneration of easily separable phenylpropiolic acid. Importantly, D-mannose and L-rhamnose-based PPG donors afforded the corresponding O-glycosides in high α-anomeric-selectivity. The reaction conditions were further explored for the synthesis of trisaccharide.
{"title":"Activation of Stable and Recyclable Phenylpropiolate Glycoside (PPG) Donors via Iron Catalysis","authors":"Anjali Aghi, Saksham Mishra, Amit Kumar","doi":"10.1055/a-2193-4615","DOIUrl":"https://doi.org/10.1055/a-2193-4615","url":null,"abstract":"Glycosylation reaction is one of the important aspects of carbohydrate chemistry, where two different units are frequently linked through the C-O bonds. In the pursuit of advancing this field, the design and development of sustainable catalytic methods for O-glycosylation, which can provide an alternate and effective tool to traditional protocols involving stoichiometric promoters and classical donors are considered as highly challenging yet important facets of glycochemistry. Herein, we report a simple and efficient Fe(III)-catalyzed method for O-glycosylation through the activation of bifunctional phenylpropiolate glycoside (PPG) donors. This mild and effective method involves the use of inexpensive, and less-toxic FeCl3 as a catalyst and easily synthesizable, benchtop stable glycosyl ester-based PPG donors, which react with various sugar as well as non-sugar-based acceptors to deliver the corresponding O-glycosides in good yields with moderate anomeric selectivity along with regeneration of easily separable phenylpropiolic acid. Importantly, D-mannose and L-rhamnose-based PPG donors afforded the corresponding O-glycosides in high α-anomeric-selectivity. The reaction conditions were further explored for the synthesis of trisaccharide.","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135992711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ligand that stabilizes the metal center is crucial to its catalytic activity. Historically dominated by phosphorus and nitrogen, sulfur has long been little considered as a hetero element for stabilizing a potentially active metal center. However, this situation is changing and we are seeing more and more examples that incorporate this element. This review provides an overview of recent transition metal-catalyzed reactions with ligands containing neutral sulfur groups, i.e. thioethers. A selection of examples published over the last decade illustrates the diversity of applications of thioether-containing ligands and shows that sulfur should be more widely used in the development of homogeneous catalysis.
{"title":"Recent progress in developing thioether-containing ligands for catalysis applications.","authors":"Stéphane Bellemin-Laponnaz, Thierry Achard","doi":"10.1055/a-2193-4927","DOIUrl":"https://doi.org/10.1055/a-2193-4927","url":null,"abstract":"The ligand that stabilizes the metal center is crucial to its catalytic activity. Historically dominated by phosphorus and nitrogen, sulfur has long been little considered as a hetero element for stabilizing a potentially active metal center. However, this situation is changing and we are seeing more and more examples that incorporate this element. This review provides an overview of recent transition metal-catalyzed reactions with ligands containing neutral sulfur groups, i.e. thioethers. A selection of examples published over the last decade illustrates the diversity of applications of thioether-containing ligands and shows that sulfur should be more widely used in the development of homogeneous catalysis.","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The benzoxazole and benzothiazole moieties were used as innate directing groups for Pd(II)- and Ru(II)-catalyzed C–H arylation of the biorelevant heterocycles 2-arylbenzoxazole and 2-arylbenzothiazole with diverse iodoarenes; palladium and ruthenium catalysis could be used complementarily. The use of σ-donor ligands, such as N,N-dimethylacetamide in the Pd(II) catalytic cycle, and σ-donor/π-acceptor ligands, such as PPh3 in the Ru(II) catalytic cycle, enhanced the arylation rate significantly and was governed by the C–H acidity of the C2-aryl ring of the 2-arylbenzoxazole or 2-arylbenzothiazole. These approaches have a broad substrate scope with respect to coupling partners, to accommodate electron-neutral, electron-rich, as well as electron-deficient iodoarenes; the C2-aryl unit of the 2-arylbenzoxazole or 2-arylbenzothiazole exhibited a high degree of site selectivity at the ortho C–H position, affording only monoarylated derivatives in decent yields; the reactions are functional-group-tolerant and applicable to gram-scale production.
{"title":"Benzoxazole/benzothiazole as an innate directing group for palladium- and ruthenium-catalyzed complementary C–H arylation: Functionalization of bio-relevant heterocyclic scaffolds","authors":"Kapileswar Seth, Mohit Maingle, Steeva Sunny, Loddipalle Sheeba, Firojkhan Rajekhan Pathan","doi":"10.1055/a-2193-4804","DOIUrl":"https://doi.org/10.1055/a-2193-4804","url":null,"abstract":"Abstract The benzoxazole and benzothiazole moieties were used as innate directing groups for Pd(II)- and Ru(II)-catalyzed C–H arylation of the biorelevant heterocycles 2-arylbenzoxazole and 2-arylbenzothiazole with diverse iodoarenes; palladium and ruthenium catalysis could be used complementarily. The use of σ-donor ligands, such as N,N-dimethylacetamide in the Pd(II) catalytic cycle, and σ-donor/π-acceptor ligands, such as PPh3 in the Ru(II) catalytic cycle, enhanced the arylation rate significantly and was governed by the C–H acidity of the C2-aryl ring of the 2-arylbenzoxazole or 2-arylbenzothiazole. These approaches have a broad substrate scope with respect to coupling partners, to accommodate electron-neutral, electron-rich, as well as electron-deficient iodoarenes; the C2-aryl unit of the 2-arylbenzoxazole or 2-arylbenzothiazole exhibited a high degree of site selectivity at the ortho C–H position, affording only monoarylated derivatives in decent yields; the reactions are functional-group-tolerant and applicable to gram-scale production.","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Over the past few years, direct C–H functionalization has become an extremely powerful synthetic tool for organic synthesis and continues to attract significant attention from organic chemists as it removes the need for pre-functionalization steps, thereby promoting step- and atom-economy.
{"title":"Editorial for the Special Topic on C–H Bond Functionalization of Heterocycles","authors":"Tharmalingam Punniyamurthy, Anil Kumar","doi":"10.1055/s-0040-1720084","DOIUrl":"https://doi.org/10.1055/s-0040-1720084","url":null,"abstract":"Over the past few years, direct C–H functionalization has become an extremely powerful synthetic tool for organic synthesis and continues to attract significant attention from organic chemists as it removes the need for pre-functionalization steps, thereby promoting step- and atom-economy.","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136142148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Linked PDF of Table of Contents","authors":"","doi":"10.1055/s-0040-1720094","DOIUrl":"https://doi.org/10.1055/s-0040-1720094","url":null,"abstract":"","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136142149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this review, a fragmentary analysis of 4,5,6,7-tetrahydroindoles was performed and, on its basis, the existing methods of their synthesis published over the past 15 years have been summarized, and analyzed, as well as, if necessary, an analysis of earlier works is carried out. The proposed reaction mechanism is considered, as well as factors that significantly influence the course of the process. Among such factors: temperature, type and content of the catalyst, promoting additives, method of the process, etc. Particular attention is paid to fundamentally new methods that make it possible to synthesize various derivatives of the mentioned heterocyclic systems from available and cheap reagents, and in some cases under environmentally benign conditions. 1 Introduction 2 Intramolecular Reactions Leading To Tetrahydroindoles 2.1 Ring Closure Reactions with N–C2 Bond Formation (a) 2.2 Ring Closure Reactions with C2–C3 Bond Formation (b) 2.3 Ring Closure Reactions with C3–C3a Bond Formation (c) 2.4 Ring Closure Reactions with C7a–N Bond Formation (e) 2.5 Ring Closure Reactions with C4–C5 Bond Formation (g) 2.6 Ring Closure Reactions with C3a–C4 Bond Formation (h) 3 Intermolecular Reactions Leading To Tetrahydroindoles 3.1 Ring Closure Reactions with N–C2 + C3–C3a Bond Formation (ac) 3.2 Ring Closure reactions with N–C2 + C7a–N Bond Formation (ae) 3.3 Ring Closure reactions with C3–C3a + C7a–N Bond formation (ce) 3.4 Ring Closure Reactions with N–C2, C3–C3a, and C7a–N Bond Formation (ace) 4 Recovery Processes (Hydrogenation) of Indoles and Oxidation of Perhydroindoles in the Synthesis of 4,5,6,7-Tetrahydroindoles 5 Conclusion
{"title":"Recent Advances in the Synthesis of Indoles with Partially Hydrogenated Benzene Ring (Tetrahydroindoles)","authors":"Vakhid A. Mamedov, Nataliya A. Zhukova","doi":"10.1055/s-0042-1751488","DOIUrl":"https://doi.org/10.1055/s-0042-1751488","url":null,"abstract":"Abstract In this review, a fragmentary analysis of 4,5,6,7-tetrahydroindoles was performed and, on its basis, the existing methods of their synthesis published over the past 15 years have been summarized, and analyzed, as well as, if necessary, an analysis of earlier works is carried out. The proposed reaction mechanism is considered, as well as factors that significantly influence the course of the process. Among such factors: temperature, type and content of the catalyst, promoting additives, method of the process, etc. Particular attention is paid to fundamentally new methods that make it possible to synthesize various derivatives of the mentioned heterocyclic systems from available and cheap reagents, and in some cases under environmentally benign conditions. 1 Introduction 2 Intramolecular Reactions Leading To Tetrahydroindoles 2.1 Ring Closure Reactions with N–C2 Bond Formation (a) 2.2 Ring Closure Reactions with C2–C3 Bond Formation (b) 2.3 Ring Closure Reactions with C3–C3a Bond Formation (c) 2.4 Ring Closure Reactions with C7a–N Bond Formation (e) 2.5 Ring Closure Reactions with C4–C5 Bond Formation (g) 2.6 Ring Closure Reactions with C3a–C4 Bond Formation (h) 3 Intermolecular Reactions Leading To Tetrahydroindoles 3.1 Ring Closure Reactions with N–C2 + C3–C3a Bond Formation (ac) 3.2 Ring Closure reactions with N–C2 + C7a–N Bond Formation (ae) 3.3 Ring Closure reactions with C3–C3a + C7a–N Bond formation (ce) 3.4 Ring Closure Reactions with N–C2, C3–C3a, and C7a–N Bond Formation (ace) 4 Recovery Processes (Hydrogenation) of Indoles and Oxidation of Perhydroindoles in the Synthesis of 4,5,6,7-Tetrahydroindoles 5 Conclusion","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135854917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In modern advances, tris(pentafluorophenyl)borane (commonly known as BCF) catalyst has risen to prominence owing to its extensive versatility in the use of myriad of organic reactions. An efficient and highly stereoselective α-C-glycosylation strategy is presented by employing a catalytic amount of B(C6F5)3 under mild reaction conditions en route to 2,3-unsaturated C-glycosides. The reaction features a broad functional group tolerance including a variety of glycals coupled with allyltrimethylsilane and trimethylsilylphenylacetylene to access the corresponding 2,3-unsaturated allyl- and alkynyl-C-glycosides with excellent α-selectivity. The reaction proceeds in good to excellent yields via concomitant borane activation of glycal donor under mild conditions.
摘要在现代发展中，三(五氟苯基)硼烷(通常称为BCF)催化剂因其广泛的多功能性在无数有机反应中使用而日益突出。在温和的反应条件下，采用一定量的B(C6F5)3催化合成2,3-不饱和c -糖苷，提出了一种高效、高立体选择性的α- c -糖基化策略。该反应具有广泛的官能团耐受性，包括多种甘醛与烯丙基三甲基硅烷和三甲基硅基苯乙炔偶联，以优异的α-选择性获得相应的2,3-不饱和烯丙基和烷基基c -糖苷。在温和的条件下，通过糖给体的硼烷活化，反应收率从高到高。
{"title":"Tris(pentafluorophenyl)borane-Catalysed Stereoselective C-Glycosylation of Glycals: A Facile Synthesis of Allyl and Alkynyl glycosides","authors":"Anand Gaurav, Zanjila Azeem, Pintu Kumar Mandal","doi":"10.1055/a-2186-7116","DOIUrl":"https://doi.org/10.1055/a-2186-7116","url":null,"abstract":"Abstract In modern advances, tris(pentafluorophenyl)borane (commonly known as BCF) catalyst has risen to prominence owing to its extensive versatility in the use of myriad of organic reactions. An efficient and highly stereoselective α-C-glycosylation strategy is presented by employing a catalytic amount of B(C6F5)3 under mild reaction conditions en route to 2,3-unsaturated C-glycosides. The reaction features a broad functional group tolerance including a variety of glycals coupled with allyltrimethylsilane and trimethylsilylphenylacetylene to access the corresponding 2,3-unsaturated allyl- and alkynyl-C-glycosides with excellent α-selectivity. The reaction proceeds in good to excellent yields via concomitant borane activation of glycal donor under mild conditions.","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ekaterina A. Zhigileva, Marina V. Molchanova, Pavel N Solyev, Alexander Korlukov, Mikhail S Baranov, Andrey A. Mikhaylov
Abstract A reaction sequence of Diels–Alder cycloaddition and Tsuji–Trost allylation was examined in terms of its application to the synthesis of kopsinine and the related Kopsia alkaloids. Results of the studies in two synthetic directions are presented herein: 1) synthesis of the properly substituted diene, required for the Diels–Alder step; and 2) model studies and optimization of the key reaction sequence in the absence of side-chain. Details on the challenging introduction of the side-chain into tetrahydrocarboline ketone and its silylation, resulting in rare but unproductive vinylogous Claisen cyclization, and the successful Mannich/Mukaiyama aldol sequence are disclosed in the first direction. In the second direction, the endo-selective Diels–Alder reaction with allyl acrylate and Tsuji–Trost allylation providing incorrect stereochemistry are disclosed. Interaction of both dienes with an alkyne provides carbazoles via Alder–Rickert reaction.
{"title":"Examination of Diels-Alder/Tsuji-Trost Route towards Kopsia Alkaloids","authors":"Ekaterina A. Zhigileva, Marina V. Molchanova, Pavel N Solyev, Alexander Korlukov, Mikhail S Baranov, Andrey A. Mikhaylov","doi":"10.1055/a-2186-7034","DOIUrl":"https://doi.org/10.1055/a-2186-7034","url":null,"abstract":"Abstract A reaction sequence of Diels–Alder cycloaddition and Tsuji–Trost allylation was examined in terms of its application to the synthesis of kopsinine and the related Kopsia alkaloids. Results of the studies in two synthetic directions are presented herein: 1) synthesis of the properly substituted diene, required for the Diels–Alder step; and 2) model studies and optimization of the key reaction sequence in the absence of side-chain. Details on the challenging introduction of the side-chain into tetrahydrocarboline ketone and its silylation, resulting in rare but unproductive vinylogous Claisen cyclization, and the successful Mannich/Mukaiyama aldol sequence are disclosed in the first direction. In the second direction, the endo-selective Diels–Alder reaction with allyl acrylate and Tsuji–Trost allylation providing incorrect stereochemistry are disclosed. Interaction of both dienes with an alkyne provides carbazoles via Alder–Rickert reaction.","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deepak K. Sharma, Samarpita Das, Harish K. Indurthi, Amita Kumari
Abstract A photoinduced approach for regioselective C-2 trifluoromethylation of indoles was achieved with CF3SO2Na under UV light irradiation (360–365 nm) at ambient conditions without any external photo activator. The key steps involve the in situ conversion of CF3SO2Na reagent to CF3 • radical under oxygen or air and UV irradiation. This proficient method has the advantages of mild reaction conditions, fair substrate tolerability, and gram scalability.
{"title":"Photoinduced Synthesis of 2-Trifluoromethylated Indoles through Oxidative Trifluoromethylation Using Langlois’ Reagent in the Absence of External Photocatalyst","authors":"Deepak K. Sharma, Samarpita Das, Harish K. Indurthi, Amita Kumari","doi":"10.1055/s-0040-1720093","DOIUrl":"https://doi.org/10.1055/s-0040-1720093","url":null,"abstract":"Abstract A photoinduced approach for regioselective C-2 trifluoromethylation of indoles was achieved with CF3SO2Na under UV light irradiation (360–365 nm) at ambient conditions without any external photo activator. The key steps involve the in situ conversion of CF3SO2Na reagent to CF3 • radical under oxygen or air and UV irradiation. This proficient method has the advantages of mild reaction conditions, fair substrate tolerability, and gram scalability.","PeriodicalId":49451,"journal":{"name":"Synthesis-Stuttgart","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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