Article
Chemistry, Multidisciplinary
Jessica Stahl, Veera Reddy Yatham, Stefano Crespi, Burkhard Koenig
Summary: Researchers reported the O-alkylation of oximes with Michael acceptors using Cs2CO3 as the catalyst, achieving stereospecific transformation with retention of oxime configuration. Irradiation with visible light in the presence of diphenyl anthracene and cerium complexes affected the E to Z configuration ratio of the oxime ether products, but complete stereocontrol was not achieved. The operationally simple protocol allows the synthesis of various O-alkylated oxime products useful as precursors for further chemical transformations.
Article
Chemistry, Multidisciplinary
Maximilian Scheruebl, Constantin G. Daniliuc, Armido Studer
Summary: The article introduces the application of arynes as radical acceptors, showing how the stable radical TEMPO can react with different ortho-substituted benzynes to generate aryl radicals for subsequent cyclizations, eventually being trapped by TEMPO. This method provides a novel approach for the convenient synthesis of various dihydrobenzofurans, oxindoles, and sultones.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Alexey A. Tsygankov, Denis Chusov
Summary: By using a fluoride anion source, well-known transition metal catalysts can be transformed into high-performance versions, increasing catalytic activity, particularly in reactions such as asymmetric cyanation of aldehydes, asymmetric Michael addition, and synthesis of cyclic carbonates.
Article
Biochemistry & Molecular Biology
Shan-Shan Li, Li-Li Zhao, Min Pan, Na Feng, Jin-Bao Peng, Ai-Jun Ma
Summary: A potassium carbonate promoted tandem oxy-Michael addition/cyclization reaction has been developed for the synthesis of diverse substituted naphthopyrans. The use of readily available and inexpensive potassium carbonate as a promoter offers an efficient and sustainable approach to prepare 2-substituted naphthopyrans.
Article
Chemistry, Multidisciplinary
Xinyu Chen, Na Yang, Wen Zeng, Lei Wang, Pinhua Li, Hongji Li
Summary: A mild dearomative [5+2]/[2+2] cycloaddition of 1H-indoles with ortho-(trimethylsilyl)aryl triflates was reported, leading to the synthesis of dibenzo[b,e]azepine derivatives in moderate to good yields. Increasing steric hindrance at the C2-position of 1H-indoles directs the reaction towards a [2+2] cycloaddition pathway. Mechanistic investigations suggest that the reaction proceeds through a [2+2] cycloaddition followed by a ring expansion to form the [5+2] cycloaddition product.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Organic
Juan A. Venegas-Nava, Francisco Yuste, Ruben Sanchez-Obregon
Summary: A transition metal free synthesis of tetrasubstituted allenes is reported, where the reaction between alpha,beta-unsaturated esters and ortho-sulfinylated benzyl-propargylic carbanions yields tetrasubstituted chiral allenes in good yields and with good isomeric ratios.
TETRAHEDRON LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Nurbey Gulia, Jaroslaw Fornalski, Adrianna Gumienna, Malgorzata Ambroziak, Slawomir Szafert
Summary: This study reports a method of palladium-catalyzed C-H arylation assisted with a 3,4,4-trimethylpyrazol-5-on directing group, which selectively provides mono- and di-ortho-arylated products. The steric hindrance between the directing group and the already introduced aryl substituent enables control of mono- vs. diarylation selectivity by the reaction temperature. A series of monosubstituted and disubstituted derivatives were obtained in good yields. In addition, a one-pot procedure for unsymmetrical double-arylation to give corresponding products was developed, and the synthesis and X-ray study of intermediate palladium metallacycles were conducted. The decarboxylative cleavage of the pyrazolone directing group under mild conditions gave synthetically useful hydrazones. Overall, this solution provides an alternative synthetic pathway for ortho arylated derivatives of arylhydrazines.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Organic
Alison P. Hart, Caroline J. Degraw, Gavin J. Rustin, Matthew G. Donahue, Julie A. Pigza
Summary: A method for the enantioselective addition of a silyl-protected masked acyl cyanide (MAC) reagent to various beta-nitrostyrenes using squaramide-organocatalysis is described. The reactions are carried out at low catalyst loadings in a freezer, yielding clean products with high enantioselectivities. The unmasking of the adducts provides functional groups in different oxidation states, highlighting the utility of MAC reagents in the preparation of beta-amino acids.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Anastasiia Klochkova, Andrey Bubyrev, Dmitry Dar'in, Olga Bakulina, Mikhail Krasavin, Viktor Sokolov
Summary: A novel tandem approach has been developed for the synthesis of various isothiazolidine 1,1-dioxides. The method involves N-alkylation of methanesulfonanilides with EWG-substituted allyl bromides followed by intramolecular Michael addition, leading to high yields and trans-diastereoselectivity. The reactivity dependency on the electronic properties of substrates has been investigated.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Physical
Martin Soto, Vicente Gotor-Fernandez, Humberto Rodriguez-Solla, Walter Baratta
Summary: The transfer hydrogenation of flavanones and ortho-hydroxychalcones catalyzed by ruthenium pincer complexes allows the synthesis of ortho-hydroxy 1,3-diarypropanols with high yield and selectivity. The amount of co-catalyst is crucial for the reduction reaction, while using pincer catalysts with specific ligands can achieve high enantiomeric excess and moderate conversion rates in the reduction of flavanones.
Article
Chemistry, Organic
Jianli Zheng, Yingqian Xu, Shaorui Song, Ling Huang, Dongdong Cao, Aiguo Zhong, Jianguo Yang, Dingben Chen
Summary: The photoredox-catalyzed 1,6-difluoromethylation of 3-methyl-4-nitro-5-styrylisoxazole with HCF2SO2Na has been developed, yielding structurally diverse difluoromethylated products. The di-, tri-, and monofluoromethylation were compared, showing the highest yield for difluoromethylation. DFT calculations revealed the nucleophilicity of CF2H radical and the lowest transition state activation energy in the difluoromethylation reaction.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Albert Artigas, Denis Hagebaum-Reignier, Yannick Carissan, Yoann Coquerel
Summary: Visualization of electron delocalization and aromaticity in selected aryne compounds, including nonplanar examples, and their reactions was achieved using multidimensional isotropic magnetic shielding contour maps. The maps showed that aryne compounds are generally less aromatic than the corresponding arene compounds, with aromaticity peaking during the reaction when approaching the transition state.
SYNTHESIS-STUTTGART
(2022)
Article
Chemistry, Organic
Xue Zhang, Jian Mo, Da-Shuang Luo, Xue-Min Niu, Hai-Feng Yu, Xiao-Bo Zhao
Summary: In this study, an effective and facile synthesis of 3-(pyrazol-1-yl) succinimides was achieved through silver-catalyzed aza-Michael addition of pyrazoles to maleimides. The reaction proceeded smoothly in the presence of 5 mol% Ag2CO3 at 100 degrees Celsius, producing the desired products in excellent yields. Notably, 3-substituted asymmetric pyrazoles exclusively gave 3-pyrazolyl succinimides, possibly due to steric hindrance preventing the formation of N-2 addition products. This method is also applicable to gram-scale synthesis.
SYNTHETIC COMMUNICATIONS
(2023)
Article
Biochemistry & Molecular Biology
Xia Chen, Xiao-Yu Zhou, Ming Bao
Summary: The study presents a synthetic method for indole derivatives, which can produce novel compounds with high yields through a catalytic reaction while preserving the integrity of various functional groups. The method can also be applied to the synthesis of similar compounds.
Article
Chemistry, Organic
Xue Zhang, Dong-xue Qiu, Wen-ting Qiu, He-ran Wang, Zu-wei Zhao, Hai-feng Yu, Guang-bo Che
Summary: An efficient Ag2CO3 catalyzed aza-Michael addition of pyrazoles to α,β-unsaturated carbonyl compounds has been developed. Using 5 mol% of Ag2CO3 as catalyst, the reaction proceeds smoothly in DCE at 120 degrees C, giving a series of N-alkylated pyrazoles in good to excellent yields. Notably, N1-alkylated pyrazoles can be obtained with high regioselectivity (N1/N2 up to above 25:1) when asymmetrically substituted pyrazoles react with α,β-unsaturated carbonyl compounds. The method is also applicable on a gram scale.
Article
Chemistry, Organic
Geeta Devi Yadav, Pooja Chaudhary, Balaram Pani, Surendra Singh
Summary: Chiral transition metal complexes with privileged ligands are efficient catalysts for various asymmetric organic transformations. Transition metal complexes of C1-symmetric pyrrolidine-based ligands have been widely used in asymmetric organic reactions. However, a comprehensive review article on the transition metal complexes of chiral C1-symmetric pyrrolidine-based ligands derived from (L)-proline has not been published.
TETRAHEDRON LETTERS
(2024)
