Article
Chemistry, Organic
Jing Sun, Xueyan Liu, Qiu Sun, Ying Han, Chao-Guo Yan
Summary: Diverse functionalized dihydrobenzofuran spiro-indanedione scaffolds were synthesized via base-promoted cyclization reaction. The selective synthesis of two diastereomeric dispiro[indene-2,1′-cyclopenta[b]benzofuran-2,3′-indolines] was achieved using DABCO or DMAP as a base promoter. Moreover, DABCO or DMAP facilitated the annulation reaction of MBH formates, resulting in the formation of spiro[cyclopropa[c]chromene-1,2′-indene]-1′,3′-diones or dispiro[indene-2,1′-cyclopenta[b]benzofuran-2,3′-indolines]. Additionally, high-yielding and highly diastereoselective synthesis of dispiro[indene-2,5′-benzofuro[2′,3′:1,5]cyclopenta[1,2-c]pyrrole-4′,3″-indolines] was achieved using MBH maleimides.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Kazuhiro Okamoto, Mizuki Tsutsui, Haruka Morizumi, Yoshikazu Kitano, Kazuhiro Chiba
Summary: Redox-induced regioselective C(sp(3))-H C-glycosidation of unactivated prolinols was achieved by controlling the anomeric reactivity of electrochemically generated iminium cations. Intermediate formed as covalent azaribose or iminium cation species in situ, with electrophilicity of intermediates adjustable by changing coexisting acids. The armed/disarmed analogy concept of traditional glycochemistry was successfully adapted to the C-glycosidation reaction, and a synthetic methodology called reactivity switching concept was developed to synthesize imino-C-nucleosides.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Anshul Jain, Anitta Regina, Akanksha Kumari, Ranjan Patra, Manikandan Paranjothy, Nirmal K. Rana
Summary: Merrifield resin-anchored pyridines were prepared and used as reusable mediators for the trans-selective cascade synthesis of 2,3-dihydroindoles. The method involved the in situ formation of N-ylides followed by Michael substitution reactions. The simple pyridine also efficiently carried out the cascade reaction. The products were further converted into valuable compounds, and the supported pyridine was reused for multiple cycles. Density functional theory calculations confirmed the lower-energy trans-selectivity pathway.
Article
Chemistry, Physical
Changha Kim, Jinwook Jeong, Mari Vellakkaran, Sungwoo Hong
Summary: A highly efficient visible-light-mediated C-H alkylation of pyridines at the C4 position using alkyl carboxylic acids as alkylating agents is reported in this study. The released N-centered radical acts as an effective oxidizing agent for single-electron transfer (SET) oxidation to regenerate the photocatalyst, making this photocatalytic system appealing from a mechanistic perspective. The strategy offers a practical approach for the C4-selective pyridylation of carboxylic acids and amino acids with various functional groups under mild, metal-free conditions.
Article
Chemistry, Physical
Changha Kim, Jinwook Jeong, Mari Vellakkaran, Sungwoo Hong
Summary: This study demonstrates an efficient photocatalytic platform for the C-H alkylation of pyridines at the C4 position using alkyl carboxylic acids as alkylating agents, offering a practical approach for the pyridylation of a diverse range of carboxylic acids and amino acids under mild, metal-free conditions.
Article
Chemistry, Multidisciplinary
Yujing Zhang, Xingchao Dai, Jixue Wang, Junxi Liang, Jabor Rabeah, Xia Tian, Xiaoqiang Yao, Yanbin Wang, Shaofeng Pang
Summary: This study introduces an in-situ generated Cu-I catalytic system for the oxidative N-formylation of N-heterocycles with methanol. The formation of N-formamides from acyclic amines is also demonstrated. A possible reaction mechanism and pathway are proposed. The formation of undesired tar-like products is related to the radicals .O-2(-) and .OOH in the catalytic system.
Article
Chemistry, Multidisciplinary
Oleg Grossmann, Rajat Maji, Miles H. Aukland, Sunggi Lee, Benjamin List
Summary: Strong and confined IDPi catalysts enable highly enantioselective substitutions of cyclic, aliphatic hemiaminal ethers with enol silanes, giving access to 2-substituted pyrrolidines, piperidines, and azepanes with high enantioselectivities. The method exhibits broad tolerance towards various enol silane nucleophiles. Mechanistic studies suggest the involvement of non-stabilized, cyclic N-(exo-acyl)iminium ions with the confined chiral counteranion as intermediates, while computational studies provide transition states that account for the observed enantioselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Shunbin Yang, Dengju Zhang, Weiguo Zuo, Guanqun Wang, Chengtao Wang, Jiyang Guo, Duona Fan, Song You, Xian Jia
Summary: In this study, a simple and efficient method was developed for the (Z)-selective transfer semihydrogenation of alkynes using in situ-generated cobalt nanoparticles and ammonia-borane. The method showed good to excellent yields and the recovered cobalt nanoparticles could be reused multiple times without significant loss of catalytic activity.
NEW JOURNAL OF CHEMISTRY
(2023)
Review
Chemistry, Multidisciplinary
Arpad Molnar
Summary: This review aims to analyze recent studies on the synthesis of five-membered nitrogen heterocycles using palladium catalysts. The focus is on studies from the last three years. The common feature of these methods is the formation of nitrogen-containing five-membered rings through the ring closing of appropriate starting materials. The selected examples demonstrate that a wide range of products, from small monocycles to condensed multi-ring systems, can be efficiently obtained with high yields and stereoselectivities under mild reaction conditions.
Article
Chemistry, Multidisciplinary
Sabir A. Molla, Debasish Ghosh, Ankur Basak, Saikat Khamarui, Dilip K. Maiti
Summary: In this study, a novel method for synthesizing highly valuable 5,6,7,8a-tetrahydropyrrolo[2,1-b]thiazoles and fused symmetrical and unsymmetrical 6,7-dihydro-5H-pyrrolo[1,2-a]imidazoles has been developed. Catalyzed by CuI with K2CO3, the method involves a decarboxylative C-N coupling reaction between phenyl glyoxal and proline, followed by regiospecific C-C and C-S coupling cyclization with dialkyl trithiocarbonate. This work significantly expands the scope and versatility of the synthetic approach for N-heterocyclic compound synthesis.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Applied
Tao Wang, Bo Huang, You-Qing Wang
Summary: Using chiral phosphoric acids as organocatalysts, a formal asymmetric (4+2) cycloaddition of 3-methylene isoindolinone and in situ-generated ortho-quinone methide substrates is achieved. This reaction allows the construction of spiro chroman-isoindolinones containing spiro-N,O-heterocycles with high enantioselectivity, with a broad substrate scope.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Rafat Kusy, Karol Grela
Summary: The (Z)-selective transfer semihydrogenation of alkynes based on in situ generated CuNPs in the presence of hydrogen donors offers an environmentally friendly method with operational simplicity, high stereo- and chemoselectivity, and functional group compatibility. Auto-oxidation of CuNPs post-semihydrogenation reaction leads to the formation of a water-soluble ammonia complex, allowing for catalyst reuse through simple phase-separation without special regeneration processes. The formed NH4B(OR)(4) can be easily converted back to ammonia-borane or boric acid, and a one-pot tandem sequence involving a Suzuki reaction followed by semihydrogenation can minimize chemical waste production.
Article
Chemistry, Organic
Vladimir V. Voronin, Maria S. Ledovskaya, Konstantin S. Rodygin, Valentine P. Ananikov
Summary: This work presents a universal synthetic approach for the synthesis of D-2-labeled nitrogen heterocycles through cycloaddition reactions using in situ generated dideuteroacetylene. By using 1,4-dioxane as a solvent, the method allowed for high levels of deuteration up to 99%. It was demonstrated to be suitable for the synthesis of various D-2-labeled heterocycles such as triazoles, isoxazoles, pyrazoles, and pyridazines.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Fathima Pilathottathil, Sreelakshmi Unnikrishnan, Alagiri Kaliyamoorthy
Summary: A transition-metal-free method for the direct synthesis of heteroaryl sulfoxides has been described. By using fi-sulfinyl esters as the source of the sulfenate ion and a Bronsted base catalyst, the desired heteroaryl sulfoxides were obtained in yields of 30 to 94%.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Huaping Xu, Xiaoyu Kong, Mengjie Cen, Ze-Feng Xu, Shengguo Duan, Chuan-Ying Li
Summary: In this study, the regioselective synthesis of dihydropyrroles was achieved through a cascade reaction. By employing a specific catalyst, the desired product was efficiently synthesized. This method has great potential for the synthesis of compounds with different ring systems.
CHEMICAL COMMUNICATIONS
(2022)
