Propylene liquid-phase epoxidation with 50–75% H2O2 is an important process for the industrial production of propylene oxide (PO). To realize a propylene epoxidation process that proceeds with low hydrogen peroxide concentration, we developed an integrated Mn/TS-1/N catalytic system via in-situ reaction of Mn/TS-1 with an N-donor ligand, affording the PO product in excellent yield with only 30 wt% H2O2. Other long-chain aliphatic epoxides were also readily synthesized by this catalytic epoxidation system. Moreover, in addition to the standard micro-pressure reactor, a continuous-flow microreactor was developed that executed the hydrogen peroxide propylene oxide (HPPO) process with excellent efficiency for 1300 hours. This innovative Mn/TS-1/N catalyzed epoxidation represents a promising direction for advancing HPPO industrial processes, offering improved efficiency while minimizing the reliance on high concentrations of H2O2.
{"title":"Aliphatic Olefin Epoxidation with Hydrogen Peroxide Catalyzed by an Integrated Mn/TS-1/N System","authors":"Shanxiu Yang, Yuyu Liu, Zhang Zhang, Bo Qian","doi":"10.1055/s-0043-1775366","DOIUrl":"https://doi.org/10.1055/s-0043-1775366","url":null,"abstract":"<p>Propylene liquid-phase epoxidation with 50–75% H<sub>2</sub>O<sub>2</sub> is an important process for the industrial production of propylene oxide (PO). To realize a propylene epoxidation process that proceeds with low hydrogen peroxide concentration, we developed an integrated Mn/TS-1/N catalytic system via in-situ reaction of Mn/TS-1 with an N-donor ligand, affording the PO product in excellent yield with only 30 wt% H<sub>2</sub>O<sub>2</sub>. Other long-chain aliphatic epoxides were also readily synthesized by this catalytic epoxidation system. Moreover, in addition to the standard micro-pressure reactor, a continuous-flow microreactor was developed that executed the hydrogen peroxide propylene oxide (HPPO) process with excellent efficiency for 1300 hours. This innovative Mn/TS-1/N catalyzed epoxidation represents a promising direction for advancing HPPO industrial processes, offering improved efficiency while minimizing the reliance on high concentrations of H<sub>2</sub>O<sub>2</sub>.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"68 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141166632","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}
A simple, efficient, and environmentally benign method for the direct C-3-alkoxycarbonylation of 2H-indazoles using alkyl carbazates has been developed under metal-free conditions at room temperature. This current protocol represents a facile access to C-3-carboxylic ester derived 2H-indazoles with wide functional group tolerance in good to excellent yields. The mechanistic studies suggest that the reaction proceeds through a radical pathway.
{"title":"Metal-Free Synthesis of C-3-Alkoxycarbonylated 2H-Indazoles Using Alkyl Carbazates","authors":"Dipti Lai, Suvam Bhattacharjee, Sumit Ghosh, Subrata Sinha, Alakananda Hajra","doi":"10.1055/a-2316-5066","DOIUrl":"https://doi.org/10.1055/a-2316-5066","url":null,"abstract":"<p>A simple, efficient, and environmentally benign method for the direct C-3-alkoxycarbonylation of 2<i>H</i>-indazoles using alkyl carbazates has been developed under metal-free conditions at room temperature. This current protocol represents a facile access to C-3-carboxylic ester derived 2<i>H</i>-indazoles with wide functional group tolerance in good to excellent yields. The mechanistic studies suggest that the reaction proceeds through a radical pathway.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"44 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141062053","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}
Here we describe a homocoupling reaction of arylboronic acid facilitated by silver carbonate, which proceeds smoothly in MeOH even at ambient temperature. The reaction exhibits broad functional group compatibility, affording a variety of symmetrical biaryls in satisfactory yields. Silver nanoparticles formed in situ serve as an accelerator in this process. Moreover, initial mechanistic investigations suggest that this transformation may occur via a radical mechanism.
{"title":"Silver-Mediated Homocoupling of Arylboronic Acids","authors":"Tomoya Sakaguchi, Kyuta Fukuoka, Takuya Matsuki, Misa Kawase, Aya Tazawa, Yasuhiro Uozumi, Yoshimasa Matsumura, Osamu Shimomura, Atsushi Ohtaka","doi":"10.1055/a-2315-8369","DOIUrl":"https://doi.org/10.1055/a-2315-8369","url":null,"abstract":"<p>Here we describe a homocoupling reaction of arylboronic acid facilitated by silver carbonate, which proceeds smoothly in MeOH even at ambient temperature. The reaction exhibits broad functional group compatibility, affording a variety of symmetrical biaryls in satisfactory yields. Silver nanoparticles formed in situ serve as an accelerator in this process. Moreover, initial mechanistic investigations suggest that this transformation may occur via a radical mechanism.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"49 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141062056","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}
Pyrazoloindolones are synthesized from N-tosylhydrazones in a one-pot multistep process which include base-promoted (i) electrocyclization reaction of N-tosylhydrazones derived from α,β-unsaturated aldehydes, (ii) aromatic nucleophilic substitution, and (iii) a domino cyclization–oxidation process under aerobic conditions.
{"title":"One-Pot Expeditious Synthesis of Pyrazoloindolones via Base-Promoted Electrocyclization, C–N Coupling and Intramolecular Oxidative Cyclization","authors":"Harshita Singh Korawat, Manoj Kumar Saini, Karmdeo Prajapati, Maya Shankar Singh, Ashok Kumar Basak","doi":"10.1055/a-2316-5200","DOIUrl":"https://doi.org/10.1055/a-2316-5200","url":null,"abstract":"<p>Pyrazoloindolones are synthesized from <i>N</i>-tosylhydrazones in a one-pot multistep process which include base-promoted (i) electrocyclization reaction of <i>N</i>-tosylhydrazones derived from α,β-unsaturated aldehydes, (ii) aromatic nucleophilic substitution, and (iii) a domino cyclization–oxidation process under aerobic conditions.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"48 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141062305","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 catalytic intermolecular cyclization of thiophenols with allylic alcohols in the presence of bismuth triflate afforded the corresponding thiochromane derivatives in a one-pot reaction. The Bi(OTf)3-catalyzed reaction was also applied to the intermolecular cyclization of diaryl disulfides with 3-methylbut-2-en-1-ol to produce the corresponding thiochromanes.
{"title":"Bismuth Triflate Catalyzed Intermolecular Cyclization of Thiophenols with Allylic Alcohols","authors":"Maki Minakawa, Taichi Inaba, Shoki Oikawa","doi":"10.1055/a-2312-0631","DOIUrl":"https://doi.org/10.1055/a-2312-0631","url":null,"abstract":"<p>The catalytic intermolecular cyclization of thiophenols with allylic alcohols in the presence of bismuth triflate afforded the corresponding thiochromane derivatives in a one-pot reaction. The Bi(OTf)<sub>3</sub>-catalyzed reaction was also applied to the intermolecular cyclization of diaryl disulfides with 3-methylbut-2-en-1-ol to produce the corresponding thiochromanes.</p>","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"22 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885178","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}
A convergent approach to the forskolin skeleton is described. Assembly of a simplified tricyclic framework is achieved in a single step via the dihydropyrone Diels–Alder reaction. Selective manipulation of the resulting cycloadduct, in conjunction with an unusual equilibration of the C8 stereocenter, provides access to scaffolds that differ in relative stereochemistry at both the A/B and B/C ring junctions.
{"title":"A Convergent Approach to the Forskolin Skeleton","authors":"Fortune O. Ononiwu, Bo Wang, Nancy I. Totah","doi":"10.1055/s-0043-1774864","DOIUrl":"https://doi.org/10.1055/s-0043-1774864","url":null,"abstract":"<p>A convergent approach to the forskolin skeleton is described. Assembly of a simplified tricyclic framework is achieved in a single step via the dihydropyrone Diels–Alder reaction. Selective manipulation of the resulting cycloadduct, in conjunction with an unusual equilibration of the C8 stereocenter, provides access to scaffolds that differ in relative stereochemistry at both the A/B and B/C ring junctions.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"52 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885179","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}
Hydrazine and its derivatives have served as a conventional bipropellant fuel for several decades. However, their extremely acute toxicity and carcinogenicity, high volatility, and environmental impact have attracted significant attention. In order to synthesize green bipropellant fuels with high density, high specific impulse, and good thermal stability, three novel N-alkyl-1,2,4-triazole–borane complexes were successfully synthesized by reacting alkylated 1,2,4-triazole coordinated with sodium borohydride in the presence of ammonium sulfate. During the droplet test with white fuming nitric acid, there was a relatively short ignition delay time of 98 ms. Additionally, these hypergolic fuels possessed a high density exceeding 1.10 g cm–3, and the specific impulse is ranging from 187 to 199 s, and the highest decomposition temperature reaches 153.4 °C. These results demonstrate their great potential as hypergolic fuels or hypergolic ionic liquid additives in the field of hypergolic materials.
{"title":"N-Alkyl-1,2,4-triazole–Borane Complexes as High-Density Hypergolic Materials","authors":"Hongfu Jia, Wenqi Ma, Jinjie Chang, Chunlin He","doi":"10.1055/a-2310-0707","DOIUrl":"https://doi.org/10.1055/a-2310-0707","url":null,"abstract":"<p>Hydrazine and its derivatives have served as a conventional bipropellant fuel for several decades. However, their extremely acute toxicity and carcinogenicity, high volatility, and environmental impact have attracted significant attention. In order to synthesize green bipropellant fuels with high density, high specific impulse, and good thermal stability, three novel <i>N</i>-alkyl-1,2,4-triazole–borane complexes were successfully synthesized by reacting alkylated 1,2,4-triazole coordinated with sodium borohydride in the presence of ammonium sulfate. During the droplet test with white fuming nitric acid, there was a relatively short ignition delay time of 98 ms. Additionally, these hypergolic fuels possessed a high density exceeding 1.10 g cm<sup>–3</sup>, and the specific impulse is ranging from 187 to 199 s, and the highest decomposition temperature reaches 153.4 °C. These results demonstrate their great potential as hypergolic fuels or hypergolic ionic liquid additives in the field of hypergolic materials.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"14 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885385","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}
A palladium-catalyzed β-C(sp3)–H arylation of aliphatic ketones by using acetohydrazide as a transient directing group has been developed. The reaction proceeds through a less-favored [5,5]-bicyclic palladacycle intermediate and is promoted by a pyridine ligand.
{"title":"Ligand-Promoted Palladium-Catalyzed β-C(sp3)–H Arylation of Ketones Using Acetohydrazide as a Transient Directing Group","authors":"Kai Jia, Junjie Wang, Xuan Wang, Chao Jiang","doi":"10.1055/a-2310-0880","DOIUrl":"https://doi.org/10.1055/a-2310-0880","url":null,"abstract":"<p>A palladium-catalyzed β-C(sp<sup>3</sup>)–H arylation of aliphatic ketones by using acetohydrazide as a transient directing group has been developed. The reaction proceeds through a less-favored [5,5]-bicyclic palladacycle intermediate and is promoted by a pyridine ligand.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"51 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140839026","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}
An efficient and practical method for the bromination of electron-rich arenes and heteroarenes was developed by using S-methyl methanethiosulfonate as the oxidant. All the bromine atoms were basically transferred to the brominated products, demonstrating the exceptional atom economy and practicality of the proposed protocol. The method reduces the amount of bromine required for this reaction system and obtains products in moderate to good yields.
{"title":"Highly Efficient and Practical Oxidative Bromination of Electron-Rich Arenes Using S-Methyl Methanethiosulfonate as the Oxidant","authors":"Shaolong Wang, Yong Zhou, Jianbo Wang, Ruolan Li, Chaoqun Huang, Huailin Pang, Xun Li","doi":"10.1055/s-0043-1763752","DOIUrl":"https://doi.org/10.1055/s-0043-1763752","url":null,"abstract":"<p>An efficient and practical method for the bromination of electron-rich arenes and heteroarenes was developed by using <i>S</i>-methyl methanethiosulfonate as the oxidant. All the bromine atoms were basically transferred to the brominated products, demonstrating the exceptional atom economy and practicality of the proposed protocol. The method reduces the amount of bromine required for this reaction system and obtains products in moderate to good yields.</p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"156 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140802238","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}
Zhi-Bo Li, Jin Zhang, Yi-Ran Shi, Hong Li, Min-Ge Yang, Wen-Qing Zhu, Qiang-Wei Fan, Yang Li
(Trifluoromethyl)sulfanylamides are an important class of organic compounds that are common among natural products and drug molecules. Here, we report a (trifluoromethyl)sulfanylation reaction using silver(I) (trifluoromethyl)sulfide as a free-radical (trifluoromethyl)sulfanylation reagent for β-amide compounds. This reaction does not require stoichiometric oxidants or additional transition-metal catalysts, and can be achieved by adding common organic acids. This method has excellent applicability and can accommodate several functional groups, including ester groups, acyl groups, and even bromo or iodo groups. Heterocyclic α,β-amides can also be readily converted into the corresponding products. This reaction also provides a new method for the synthesis of deuterated (trifluoromethyl)sulfanylamides.
{"title":"AgSCF3 Radical Addition Based on an Oxidant-Free α,β-Amide (Trifluoromethyl)sulfanylation Reaction","authors":"Zhi-Bo Li, Jin Zhang, Yi-Ran Shi, Hong Li, Min-Ge Yang, Wen-Qing Zhu, Qiang-Wei Fan, Yang Li","doi":"10.1055/s-0043-1763759","DOIUrl":"https://doi.org/10.1055/s-0043-1763759","url":null,"abstract":"<p>(Trifluoromethyl)sulfanylamides are an important class of organic compounds that are common among natural products and drug molecules. Here, we report a (trifluoromethyl)sulfanylation reaction using silver(I) (trifluoromethyl)sulfide as a free-radical (trifluoromethyl)sulfanylation reagent for β-amide compounds. This reaction does not require stoichiometric oxidants or additional transition-metal catalysts, and can be achieved by adding common organic acids. This method has excellent applicability and can accommodate several functional groups, including ester groups, acyl groups, and even bromo or iodo groups. Heterocyclic α,β-amides can also be readily converted into the corresponding products. This reaction also provides a new method for the synthesis of deuterated (trifluoromethyl)sulfanylamides. </p> ","PeriodicalId":22319,"journal":{"name":"Synlett","volume":"6 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140625890","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}