Article
Chemistry, Organic
Prasoon Raj Singh, Pratibha Kalaramna, Shamsad Ali, Avijit Goswami
Summary: A simple protocol has been developed to access thio-/selenopyrrolines through a (3+2)-cycloaddition reaction using SnCl4 as a Lewis acid catalyst. Good chemoselectivity was observed when DACs were treated, indicating that thiocyanate is more reactive than nitrile moiety in such reactions.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Grzegorz Mloston, Mateusz Kowalczyk, Andre U. Augustin, Peter G. Jones, Daniel B. Werz
Summary: The reactivity of donor-acceptor cyclopropanes towards thioketenes was investigated, leading to the formation of exocyclic thioenol ethers in moderate to good yields in a (3+2)-cycloaddition using Sc(OTf)(3) as a Lewis acidic catalyst. Unsymmetrical thioketenes provided E/Z mixtures at the double bond, with the Z isomer being preferred.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Nils L. Ahlburg, Oliver Hergert, Peter G. Jones, Daniel B. Werz
Summary: A novel class of highly activated donor-acceptor cyclopropanes with a single vinylogous acceptor is presented. These moieties undergo cycloaddition reactions with various substrates to form carbo- and heterocycles. The stereochemical outcome can be controlled by the choice of catalyst. Mechanistic and kinetic experiments were conducted to explain the catalytic cycle and stereoselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Ming Bao, Karlos Lopez, Raj Gurung, Hadi Arman, Michael P. Doyle
Summary: A highly enantioselective synthesis of chiral dihydro-3H-carbazole-2-carboxylate derivatives is achieved via a one-pot cascade reaction catalyzed by nickel(II) perchlorate hexahydrate and scandium(III) trifluoromethanesulfonate. The reaction proceeds under mild conditions and provides the desired products in high yields and enantioretention. Furthermore, these dihydro-3H-carbazole-2-carboxylates can be transformed into decarboxylated compounds through hydrolysis and decarboxylation under unexpectedly mild reaction conditions, giving moderate yields with high retention of enantiomeric purity.
Article
Chemistry, Physical
Ming Bao, Karlos Lopez, Raj Gurung, Hadi Arman, Michael P. Doyle
Summary: A highly enantioselective synthesis of chiral dihydro-3H-carbazole-2-carboxylate derivatives is achieved via a one-pot cyclopentannulation-rearrangement cascade reaction. The reaction is catalyzed by nickel(II) perchlorate hexahydrate and scandium(III) trifluoromethanesulfonate, and involves the use of 3-methylindole and non-racemic donor-acceptor cyclopropanes. The resulting products show high yields and enantioretention under mild reaction conditions, and further transformation into decarboxylated compounds can be achieved with moderate yields and high enantiomeric purity.
Article
Chemistry, Applied
Pavel G. Sergeev, Roman A. Novikov, Yury V. Tomilov
Summary: The reactions of donor-acceptor cyclopropanes and isomeric beta-styrylmalonates with conformationally non-rigid alpha,beta-unsaturated imines in the presence of Lewis acids were studied, with a focus on developing a method for the diastereoselective synthesis of substituted trans,trans-tetrahydropyridines. Different Lewis acid catalytic systems were employed, resulting in the formation of products with significant diastereoselectivity over different cycloaddition pathways. Appropriate mechanistic and stereochemical models were proposed based on the results obtained.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Review
Chemistry, Physical
Ming Bao, Michael P. Doyle
Summary: The [3+n]-cycloaddition reactions using chiral catalysts and racemic cyclopropanes or achiral catalysts and chiral, non-racemic cyclopropanes have proven to be important transformations for the synthesis of carbocyclic and heterocyclic compounds, showing both mechanistic and structural advantages in ring formation.
Article
Chemistry, Organic
Wenhui Li, Jianying Lin, Shuangping Huang, Qiang Liu, Wenlong Wei, Xing Li
Summary: Highly functionalized 1,5,2-dioxazinanes can be synthesized efficiently by a Sc(OTf)(3)-catalyzed chemoselective [3+3] cycloaddition between N-arylnitrones and a series of donor-acceptor oxiranes. The reaction involves the in situ generation of 1,3-dipoles through Sc(OTf)(3)-catalyzed C-C bond cleavage of oxiranes, resulting in moderate to high yields for most substrates. This transformation showcases the C-C bond cleavage of donor-acceptor oxiranes, easily accessible starting materials, and mild reaction conditions.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Anu Jacob, Peter G. G. Jones, Daniel B. B. Werz
Summary: A new method for synthesizing tetrahydroselenophenes with exocyclic double bonds was reported, which involves the reaction of donor-acceptor cyclopropanes (DACs) with lithium alkynylselenolates in the presence of In(OTf)3. The method has a broad substrate scope and high yields.
ORGANIC CHEMISTRY FRONTIERS
(2022)
Review
Chemistry, Multidisciplinary
Yong Xia, Xiaohua Liu, Xiaoming Feng
Summary: The donor-acceptor (D-A) cyclopropanes, due to the synergistic push-pull effect of vicinal electron-donating and electron-withdrawing groups, are recognized as powerful building blocks for generating polyfunctional reactive intermediates. Enantioselective reactions of D-A cyclopropanes provide an efficient approach to enantioenriched acyclic and cyclic compounds. Chiral Lewis/Bronsted acids, transition metals, and organocatalysts have been designed for such transformations, including ring-openings, annulations, and rearrangements.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Vincent Pirenne, Emma G. L. Robert, Jerome Waser
Summary: Efficient catalytic activation of donor-acceptor aminocyclopropanes lacking the commonly used diester acceptor was achieved in a (3 + 2) dearomative annulation with indoles, yielding cycloadducts in high yields and high diastereomeric ratios, leading to tricyclic indoline frameworks containing four stereogenic centers.
Article
Chemistry, Multidisciplinary
Yuri Saito, Jun Kikuchi, Chen Wang, Naohiko Yoshikai
Summary: We report the design and development of Co/Al and Co/Mg bimetallic catalysts supported by a phosphine/secondary phosphine oxide (PSPO) bifunctional ligand for the selective C-H alkenylation of nitrogen-containing heteroarenes with alkynes. These catalysts enable the alkenylation of pyridine, pyridone, and imidazo[1,2-a]pyridine derivatives at the C-H site proximal to the Lewis basic nitrogen or oxygen atom, with a selectivity profile distinct from previously developed cobalt-diphosphine/aluminum catalyst. The alkenylated products were obtained in moderate to good yields using various heterocycles and differently substituted internal alkynes. Kinetic isotope effect experiments suggest the irreversibility of the C-H activation step, the relevance of which to the rate-limiting step depends on the reaction conditions. Density functional theory calculations indicate that ligand-to-ligand hydrogen transfer is the common mechanism of C-H activation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Simon Kolb, Martin Petzold, Felix Brandt, Peter G. Jones, Christoph R. Jacob, Daniel B. Werz
Summary: The first electrochemical activation of D-A cyclopropanes and D-A cyclobutanes leading to the formation of highly reactive radical cations is described. Molecular oxygen is formally inserted after direct or DDQ-assisted anodic oxidation of the strained carbocycles, delivering beta- and gamma-hydroxy ketones and 1,2-dioxanes electrocatalytically. Insights into the mechanism of the oxidative process are obtained experimentally and by additional quantum-chemical calculations, demonstrating the synthetic potential of the reaction products through diverse derivatizations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Raghuramaiah Mandadapu, Amol Satish Dehade, Shrikant Abhiman Shete, Mark Montgomery, Vikas Sikervar, Ravindra Sonawane
Summary: Two different Lewis acids were utilized to achieve regioselective [3+2] and [3+3] cycloaddition reactions of an azomethine imine with activated cyclopropanes, resulting in moderate yields of tetrahydropyrazolone derivatives and tricyclic tetrahydrofuran derivatives as well as high regioselectivity in forming hexahydropyridazinone derivatives.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Multidisciplinary
Stefano Nicolai, Jerome Waser
Summary: This study reports a Lewis acid catalyzed (4+3) annulative addition reaction for the efficient synthesis of densely substituted azepanes. The reaction achieved good yields and high diastereoselectivity under mild conditions using ytterbium triflate or copper triflate with a trisoxazoline ligand as the catalyst. The obtained cycloadducts were convenient substrates for further modifications.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
