Palladium-Catalyzed Diastereo- and Enantioselective [3 + 2] Cycloaddition of Vinylcyclopropanes with Azadienes: Efficient Access to Chiral Spirocycles

Organic Letters, Journal Year: 2021, Volume and Issue: 23(3), P. 826 - 831

Published: Jan. 27, 2021

Benzofuran-derived azadienes (BDAs) have been widely used as four-atom synthons in transition-metal-mediated cycloaddition reactions, while the exploitation of their reactivity a two-atom unit to construct spirocycles is still underdeveloped. Herein, we reported first palladium(0)-catalyzed diastereo- and enantioselective [3 + 2] annulation vinylcyclopropanes (VCPs) BDAs. This transformation featured with broad substrate scope (31 examples), allowing for facile access variety enantioenriched bearing quaternary stereogenic center good yields excellent regio-, diastereo-, enantioselectivities (up 93% yield, >20:1 dr, mostly >99% ee) under mild reaction conditions. Moreover, spirocyclic products could be efficiently converted structurally complex tricyclo[8.3.0.01,5]-azatridecane tricyclo[7.3.0.01,5]-azadodecane skeletons.

Language: Английский

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Cycloaddition of cyclopropanes for the elaboration of medium-sized carbocycles

Organic & Biomolecular Chemistry, Journal Year: 2021, Volume and Issue: 19(26), P. 5702 - 5724

Published: Jan. 1, 2021

In this review, we describe the important advances in cycloaddition methodologies involving cyclopropanes for construction of seven-, eight- and nine-membered carbocycles, with a particular attention to variety mechanisms involved.

Language: Английский

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Expanding Stereoelectronic Limits of endo-tet Cyclizations: Synthesis of Benz[b]azepines from Donor–Acceptor Cyclopropanes

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(34), P. 13952 - 13961

Published: Aug. 18, 2021

The importance of intramolecular constraints in cyclic transition-state geometries is especially pronounced n-endo-tet cyclizations, where the usual backside approach a nucleophile to breaking bond impossible for rings containing less than eight atoms. Herein, we expand limits endo-tet cyclizations and show that donor–acceptor cyclopropanes can provide seven-membered ring via genuine 6-endo-tet process. Substrates N-alkyl-N-arylcarbamoyl moiety as an acceptor group undergo Lewis acid-induced cyclization form tetrahydrobenz[b]azepin-2-ones high yields. reaction proceeds with inversion configuration at electrophilic carbon. In this process, formally six-membered transition state yields pre-existing cycle merged into forming ring. stereochemistry products be controlled by time nature acid, opening access both diastereomers tuning conditions.

Language: Английский

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Catalytic Asymmetric C(sp³)–H Carbene Insertion Approach to Access Enantioenriched 3-Fluoroalkyl 2,3-Dihydrobenzofurans

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(22), P. 14293 - 14301

Published: Nov. 11, 2021

Fluoroalkyl diazo compounds are versatile reagents for introducing fluoroalkyl groups into organic compounds. Despite their uses as carbene precursors in many reactions, asymmetric insertion C(sp3)–H bonds remains quite rare. Herein we report the rhodium-catalyzed enantioselective intramolecular of a ether α-C(sp3)–H under mild conditions using operationally safe and easily decomposable N-triftosylhydrazones source. This method enables efficient synthesis range previously inaccessible chiral 2,3-dihydrobenzofuran derivatives good to high yields with excellent diastereoselectivities enantioselectivities. The usefulness this transformation is exemplified straightforward several CF3 analogues natural products bioactive molecules. DFT calculations provide insights underlying stepwise pathway origin enantioselectivity.

Language: Английский

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Stereoretentive Catalytic [3+2]-Cycloaddition/Rearrangement/Decarboxylation Reactions of Indoles with Non-Racemic Donor–Acceptor Cyclopropanes

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(3), P. 1621 - 1629

Published: Jan. 12, 2023

A highly enantioselective synthesis of chiral dihydro-3H-carbazole-2-carboxylate derivatives is reported via a "one-pot" cyclopentannulation-rearrangement cascade reaction that sequentially catalyzed by nickel(II) perchlorate hexahydrate and scandium(III) trifluoromethanesulfonate with 3-methylindole non-racemic donor–acceptor cyclopropanes in high yields enantioretention under mild conditions. Highly diastereoselective [3+2]-cycloaddition dependent on substituents. In addition, further transformation these dihydro-3H-carbazole-2-carboxylates hydrolysis decarboxylation unexpectedly conditions provides straightforward access to the decarboxylated compounds moderate retention enantiomeric purity.

Language: Английский

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