Article
Chemistry, Organic
Shi-Lu Zheng, Yun-Xiang Zou, Zhong Wen, Jia-Fu Lin, Ling-Hui Gu, Long Chen
Summary: A facile synthesis of 2-phosphorylated 2H-chromenes has been achieved via a Y(OTf)(3)-catalyzed dehydrative coupling of 2H-chromene hemiacetals with P(O)-H compounds. This protocol features low catalyst loading, mild reaction conditions, broad substrate scope, and easy elaboration of the products.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
Article
Chemistry, Organic
Lodsna Borkotoky, Satheesh Borra, Ram Awatar Maurya
Summary: A DBU-mediated annulation reaction was developed for the synthesis of biologically relevant pyrrolocoumarins using 4-(benzylthio/arylthio)-2-oxo-2H-chromene-3-carbaldehydes and phenacyl azides. This operationally simple and unique synthetic strategy allows the formation of desired pyrrolocoumarin in good yields (67-84%), and generates a new C-C and C-N bond in the overall process.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Anilkumar Gunnam, Alagesan Balasubramani, Goverdhan Mehta
Summary: The recursive anion-mediated activation of o-bis-ynones leads to the one-pot synthesis of 1-indenones, and further reactions result in the access to the embellished cyclopenta[a]inden-8(2H)-one core and its spiroannulated analogues.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Wen-Qing Zhu, Zi-Wei Zhang, Wen-Yong Han, Yu-Chen Fang, Ping Yang, Lin-Qiang Li, Yong-Zheng Chen
Summary: A novel palladium-catalyzed three-component reaction has been developed, which utilizes three different types of compounds to produce a range of new compounds in moderate to good yields. Significantly, aziridine was used as a vinylidene unit for the first time in the products.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Organic
Narendra Kumar Vaishanv, Mohd Khalid Zaheer, Sandeep Kumar, Ruchir Kant, Kishor Mohanan
Summary: An unprecedented Cs2CO3-mediated intramolecular cyclization/rearrangement cascade has been discovered, which transforms alpha-nitroethylallenic esters to functionalized pyrrolin-2-ones. This reaction provides a new and practical approach for synthesizing medicinally privileged 5-hydroxy-3-pyrrolin-2-ones under mild conditions. The broad potential of this new method was demonstrated by an efficient Au/Ag-catalyzed heteroarylation of 5-hydroxy-3-pyrrolin-2-ones using electron-rich heteroarenes to produce heteroaryl-lactam derivatives.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Ke Li, Zhenjie Gan, Er-Qing Li, Zheng Duan
Summary: A novel phosphine-catalyzed (4 + 2) cyclization reaction has been reported for the generation of functionalized dihydropyran skeletons from electron-deficient conjugated dienes and enones. Mechanistic investigation reveals the formation of a new phosphonium zwitterion, which undergoes consecutive reactions. An asymmetric variant has also been developed through efficient and economical chiral phosphine catalysis.
Article
Biochemistry & Molecular Biology
Kwabena Fobi, Ebenezer Ametsetor, Richard A. Bunce
Summary: A domino aldol-SNAr-dehydration [3+3] annulation strategy is used to fuse six-membered cyclic amides onto aromatic substrates. 2-Arylacetamides are reacted with 2-fluorobenzaldehyde derivatives activated toward SNAr reaction by an electron-withdrawing substituent (NO2, CN, CF3, CO2Me) at C5 to prepare 3,6-disubstituted quinolin-2(1H)-ones. Similarly, 3-substituted 1,8-naphthyridin-2(1H)-ones are derived from 2-fluoronicotinaldehyde. Fifteen examples are reported, and two possible mechanistic scenarios are presented and discussed.
Article
Chemistry, Organic
Hui Xie, Yao-Fu Zeng, Bing Shu, Jin-Yi Liang, Zhuo-Jun Huang, Shao-Yong Chen, Yi-Chuan Zheng, Yan-Zhi Liu, Shang-Shi Zhang
Summary: A tandem rhodium(III)-catalyzed system was developed for the synthesis of 3,4-dihydroisoquinolin-1(2H)-one by coupling N-methoxy-3-methylbenzamide with 2-methylidenetrimethylene carbonate. The method showed excellent substrate scope, functional-group compatibility, and smooth reaction under mild conditions. Mechanism studies indicated the vital role of the rhodium(III) catalyst in C-H-allylation and N-alkylation cyclization.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Xiaojie Ren, Xiao-Yong Duan, Yanting Li, Jiahan Li, Jing Qi
Summary: This study describes the NHC-catalyzed diastereoselective and enantioselective [12 + 2] higher-order cycloadditions of 5H-benzo[a]-pyrrolizine-3-carbaldehydes with cyclic sulfonic imines. Optically pure polycyclic piperazin-2-ones were successfully synthesized under mild reaction conditions with excellent diastereoselectivities and enantioselectivities. The resulting chiral polycyclic piperazin-2-ones could be transformed to planar-chiral nine-membered cyclic amides via squaramide-catalyzed asymmetric ring-expansion reactions.
Article
Chemistry, Organic
Jianbo Zhao, Shengshu Lei, Min Wu, Can Pang, Hao Li
Summary: A three-component synthesis of pyridazinones using Cu(OTf)2 as catalyst has been developed, which shows high tolerance towards various functional groups including aliphatic, aromatic and hetero-aromatic aldehydes, and gives moderate to high yields of 2,6-diaryl-4,5-dihydropyridazin-3(2H)-one products.
TETRAHEDRON LETTERS
(2023)
Article
Chemistry, Organic
Liulin Jiao, Bo Zhang, Bohong Qu, Ruirui Zhai, Xun Chen
Summary: This article reports a novel and efficient Rh(III)-catalyzed direct C-H bond tandem annulation, which involves the cleavage of two C-H bonds and leads to a series of valuable tetrahydrocarbazol-4-ones. The method offers several advantages, including readily available starting materials, broad functional group tolerance, and in situ generation of carbene precursors. Importantly, some reaction products showed promising antiproliferative activity in cancer cell lines.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Applied
Wen-Zhe Ji, Hao-Nan Shi, Ping Wei, Wen-Juan Hao, Shu-Jiang Tu, Bo Jiang
Summary: A general and efficient photocatalytic annulation-carbohalogenation of 1,7-enynes with various alkyl halides was reported, leading to the atom-economic synthesis of functionalized 3,4-dihydronaphthalen-1(2H)-ones with good yields and high stereoselectivity under mild conditions. The reaction demonstrated remarkable compatibility with alkyl halides as bifunctional reagents and enabled wide substrate scope, high functional group tolerance, and 100% atom utilization.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Organic
Pragya Pali, Dhananjay Yadav, Gaurav Shukla, Maya Shankar Singh
Summary: This study presents an efficient copper-catalyzed intermolecular radical [3+2] annulation of thioamides with AIBN, allowing for the synthesis of thiazolidin-4-ones in good yields. The reaction is operationally simple and the products exhibit an asymmetric stereochemistry.
SYNTHESIS-STUTTGART
(2022)
Article
Chemistry, Organic
Yi-Feng Qiu, Jian-He Cao, Shutao Wang, Qiang Wang, Ming Li, Jun-Jiao Wang, Zheng-Jun Quan, Xi-Cun Wang
Summary: The p-TsOH/halotrimethylsilane facilitated cycloketonization of gamma-hydroxyl ynones is described, enabling the one-step synthesis of polysubstituted 3(2H)-furanone products. Remarkably, the reaction exhibits excellent regio- and chemoselectivity with the addition of very small quantities of p-toluenesulfonic acid and water.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Fang Xie, Shijie Dong, Yajun Sun, Wenxing Liu, Xiaodan Liu, Lu Liu, Qin Zhao, Jiangli Wang
Summary: A CuH-catalyzed coupling reaction between aryl alkenes and 3-aryl-2H-azirines has been developed to synthesize optically active beta,beta-disubstituted ketones. The reaction proceeds via the regioselective attack of a chiral alkylcopper complex on the N-C2 bonds of azirines, generating chiral beta-aryl imines that can be further hydrolyzed to give ketones. This method provides a novel and efficient approach for the synthesis of chiral beta,beta-disubstituted ketones under mild conditions.
Article
Chemistry, Organic
Dhananjay Yadav, Abhijeet Srivastava, Monish Arbaz Ansari, Maya Shankar Singh
Summary: The unique properties of ketoximes are used for synthesizing heterocycles, but the potential for light absorption and photoelectron transfer processes remains challenging. By controlling the direct excitation of ketoxime tacticity, unconventional reaction pathways for alkynyl sulfides can be unlocked that cannot be achieved through traditional activation.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Pragya Pali, Gaurav Shukla, Priya Saha, Maya Shankar Singh
Summary: An operationally simple and sustainable one-pot photo-oxidative formal [3 + 2] heterocyclization of beta-ketothioamides with aryldiazonium salts catalyzed by Ru(bpy)(3)Cl-2 has been realized to provide 2,4-disubstituted 5-imino-1,2,3-thiadiazoles in good to high yields under mild reaction conditions for the first time. The reaction proceeded via an a-phenylhydrazone adduct of thioamides leading to 1,2,3-thiadiazoles via N-S bond formation at room temperature. Notably, the products possess Z-stereochemistry with regard to the exocyclic C = N double bond at the 5-position of the ring.
Article
Biochemistry & Molecular Biology
Ayaka Morimoto, Yuhei Hosokawa, Hiromu Miyamoto, Rajiv Kumar Verma, Shigenori Iwai, Ryuma Sato, Junpei Yamamoto
Summary: This study comprehensively characterized the binding of 8-HDF to Xenopus (6-4) photolyase and investigated its impact on efficient energy transfer, revealing the crucial role of Coulombic interactions between positively charged residues in the protein and the phenoxide moiety in 8-HDF.
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
(2021)
Article
Chemistry, Organic
Priya Saha, Monish Arbaz Ansari, Gaurav Shukla, Maya Shankar Singh
Summary: A one-pot protocol was developed for the synthesis of symmetrical and unsymmetrical alpha-oxoketene S,S-/N,S-acetals through chemoselective alkylation of alpha-enolic dithioesters using Mitsunobu chemistry at room temperature. This user-friendly method tolerates a wide range of alcohols and alpha-enolic dithioesters/beta-ketothioamides, providing good yields and highly selective C-S functionalization with E/Z-stereoselectivity.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Monish Arbaz Ansari, Ganesh Kumar, Maya Shankar Singh
Summary: Here, we described an efficient method for the construction of highly functionalized diazirines from carbohydrazide and diazo-substituted hypervalent iodine reagents. The method is user applicable and easy to practice with unambiguous transformation conditions. Notably, D-glucose, menthol, aspirin, proline, and lithocholic acid were efficiently diazirinated. Furthermore, the method is mild, robust, and highly selective, converting various aryl, alkyl, benzyl, and heterocyclic hydrazides into the corresponding diazirine derivatives.
Article
Chemistry, Organic
S. K. Abu Saleh, Atanu Hazra, Maya Shankar Singh, Saumen Hajra
Summary: This study demonstrates the use of Bronsted acid and/or Lewis acid catalysis for the selective C3-allylation and formal [3 + 2]-annulation reactions, leading to the direct synthesis of 3-allyl-3-aminomethyl oxindoles and 5-silyl methyl spiro[pyrrolidine-3,3'-oxindoles]. The reaction of nonracemic spiroaziridines with allyl-Grignard reagent under catalyst-free conditions also provides good stereoselectivity in the formation of 3-allyl-3-aminomethyl oxindoles (ee up to 80%). The allylation protocol is useful for the efficient synthesis of coerulescine and various 5'-substituted spiro[pyrrolidine-3,3'-oxindoles].
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Monish Arbaz Ansari, Shahnawaz Khan, Subhasish Ray, Gaurav Shukla, Maya Shankar Singh
Summary: A one-pot annulative coupling reaction of 1,2,3,4-tetrahydroisoquinolines (THIQs) with hypervalent iodine(III) species aryliodonio diazo compounds has been developed, leading to the direct construction of 1,2,4-triazolo[3,4-a]isoquinoline derivatives at room temperature in open air. This reaction involves a [2 + 3] cascade annulation of nucleophilic THIQ with an electrophilic aryliodonio diazo compound, enabling the N-H and alpha-C1(sp3)-H difunctionalization of THIQ.
Article
Chemistry, Organic
Dhananjay Yadav, Maya Shankar Singh
Summary: A simple and efficient cascade approach for the synthesis of a series of 1,3-thiazinanes has been developed using beta-ketothioamide and epichlorohydrin in an intermolecular [3+3] heteroannulative coupling. This method offers several advantages, such as avoiding potential toxicity, easy work-up, and high yields, and it can be performed using readily available starting materials under transition-metal-free conditions.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Shahnawaz Khan, Monish Arbaz Ansari, Maya Shankar Singh
Summary: This study presents a chemo- and regioselective cascade annulation between fi-ketothioamides and diazo-substituted hypervalent iodine reagents under transition-metal-free and base-free conditions at room temperature. A divergent construction of fused-heterocyclic scaffold thiazolothiadiazoles has been achieved with the advantages of operational simplicity, scalability, broad substrate compatibility, and mild reaction conditions. This one-pot strategy not only avoids potential toxicity but also broadens the arsenal of synthetic methods to obtain fused N,S-heterocyclic frameworks.
Article
Chemistry, Organic
Pragya Pali, Maya Shankar Singh
Summary: A simple and efficient domino strategy was developed for the synthesis of 1,2-dithioles using easily accessible dithioesters and aryl isothiocyanates. The reaction proceeded smoothly at room temperature without the need for a catalyst or additive, and produced high yields of 1,2-dithioles with diverse functional groups. The use of cheap and readily available reagents, O-2 as a green oxidant, and the ability for gram-scale synthesis are notable features of this approach. The formation of S-S bonds and cascade ring construction in this reaction were found to proceed through a radical pathway.
Article
Chemistry, Applied
Anup Kumar Yadav, Vipin Kumar, Pragya Pali, Subhasish Ray, Abhineet Verma, Maya Shankar Singh
Summary: Here, a one-pot viable protocol for synthesizing tetrasubstituted 2-aminothiophenes using readily accessible α-enolic dithioesters and abundant fumaronitrile under transition metal-free conditions at room temperature in open air is reported. The reaction proceeds via successive Michael-type addition/intramolecular cyclization/isomerization cascades. The added features of this protocol include benign conditions, exclusive regio- and chemoselectivity, excellent atom-/step-economy, easy purification, and tolerance of a wide range of functional groups. It not only provides a robust and modular approach to various 2-aminothiophenes, but also demonstrates the potential of dithioesters and fumaronitrile in intermolecular cross-coupling reactions, expanding the arsenal of synthetic methods.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Organic
Ganesh Kumar, Subhasish Ray, Gaurav Shukla, Maya Shankar Singh
Summary: A one-pot synthesis of bench-stable quinoxaline N-oxides was achieved using a-oxoketene N,S-acetals and tert-butyl nitrite in open air. The double functionalization of N,S-acetals proceeds via an unexpected (Csp(2))-H nitrosation by NO radical and subsequent intramolecular N-arylation leading to quinoxaline, which is then oxidized to quinoxaline N-oxides. This protocol offers short reaction time, good functional group tolerance, and mild conditions without the need for a catalyst or external additive.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Organic
Subhasish Ray, Anup Kumar Yadav, Saurabh Singh, Monish Arbaz Ansari, Maya Shankar Singh
Summary: A one-pot electronically controlled [4 + 2] cycloaddition reaction between in situ generated benzyne and 2-arylidene-1-indenones has been discovered, allowing the construction of novel spirocyclic frameworks in a regio- and diastereoselective manner. This protocol offers simplicity, good functional group tolerance, and avoids the need for metal catalysts and external additives. The synthetic application of 2-arylidene-1-indenones has been extended, providing easy access to valuable 10'H-spiro[indene-2,9'-phenanthren]-1(3H)-ones in good yields.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
S. K. Abu Saleh, Atanu Hazra, Maya Shankar Singh, Saumen Hajra
Summary: The selective C3-allylation and formal [3 + 2]-annulation of spiro-aziridine oxindoles with allylsilanes can be catalyzed by Bronsted acid and/or Lewis acid, resulting in the formation of 3-allyl-3-aminomethyl oxindoles and 5-silyl methyl spiro[pyrrolidine-3,3'-oxindoles], respectively. Acid-catalyzed methods lack stereoselectivity when chiral spiroaziridines are used, but good stereoselectivity can be achieved through the reaction of nonracemic spiroaziridines with allyl-Grignard reagent under catalyst-free conditions. This allylation protocol is useful for the synthesis of biologically active compounds, such as coerulescine and various 5'-substituted spiro[pyrrolidine-3,3'-oxindoles].
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Sonam Soni, Gaurav Shukla, Maya Shankar Singh
Summary: Magnesium catalysis was found to be efficient for [3 + 3] chemo- and diastereoselective heteroannulation, leading to highly substituted 3,4-dihydro-2H-thiopyrans in excellent yields. The compatibility with a wide range of functional groups makes this domino formation of C-C and C-S bonds interesting.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2022)
