Organocatalytic asymmetric dearomatization of 3-nitroindoles and 3-nitrobenzothiophenes by reaction with ethyl 4-mercapto-2-butenoate has been developed. A range of chiral tetrahydrothiopheneindolines and tetrahydrothiophenebenzothiophenes bearing three contiguous stereocenters are obtained in high yields with good diastereoselectivities and excellent enantioselectivities. This is the first example of thiol-triggered catalytic asymmetric dearomatization of 3-nitroindoles and 3-nitrobenzothiophenes.
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http://dx.doi.org/10.1021/acs.orglett.9b01688 | DOI Listing |
Org Lett
December 2024
State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
A bioinspired alkylation dearomatization reaction was developed to construct the 5/6/6 fused-spiro tricyclic core framework and spiro-quaternary carbon chiral center. The usage of this approach for assembling these natural products of spirocyclic polycyclic polyprenylated acylphloroglucinols with an octahydrospiro-[cyclohexan-1,5'-indene] core is demonstrated by the first asymmetric total synthesis of highly oxidized hyperbeanol A.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Guangxi Normal University, School of Chemistry and Pharmaceutical Sciences, 15 Yucai Road, 541004, Guilin, CHINA.
Skeletal editing represents an attractive strategy for adding complexity to a given molecular scaffold in chemical synthesis. Isodesmic reactions provide a complementary skeletal editing approach for the redistribution of chemical bonds in chemical synthesis. However, catalytic enantioselective isodesmic reaction is extremely scarce and enantioselective isodesmic reaction to synthesize atropisomeric compounds is unknown.
View Article and Find Full Text PDFChemistry
December 2024
Department of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
We present a comprehensive account on the evolution of a synthetic platform for a subfamily of ent-pimaranes. For the most complex member, norflickinflimiod C, five distinct strategies relying on either cationic or radical polyene cyclizations to construct the requisite tricyclic carbon scaffold were explored. Insights from early and late stage oxidative and reductive dearomatization studies ultimately led to a mild, rhodium-catalyzed arene hydrogenation for the final synthetic route.
View Article and Find Full Text PDFOrg Lett
December 2024
Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences & Research Unit of Peptide Science, Chinese Academy of Medical Sciences, 2019RU066, Lanzhou University, Lanzhou 730000, China.
To advance more efficient dearomatization approaches, we present herein an organocatalyzed asymmetric double dearomatization reaction of tricyclic phenols and alkoxybenzenes by leveraging a novel steric hindrance-regulated dearomatization strategy for nonfunctionalized phenols. This protocol allows the efficient synthesis of structurally complex polycyclic diketones with four tertiary carbon centers under mild conditions while also showcasing the potential of multiple dearomatizations for building intricate molecular frameworks from simple starting materials.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, College of Science, Southern University of Science and Technology Guangming Advanced Research Institute, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China.
Organocatalytic chemo- and enantioselective reactions of 2-amino-3-subsituted indoles have been achieved for the first time. Via asymmetric allylic alkylation of Morita-Baylis-Hillman carbonates, organocatalytic enantioselective dearomatization of 2-amino-3-subsituted indoles afforded an array of enantioenriched 3,3-disubstituted indolin-2-imines bearing a quaternary carbon stereocenter in 34-79% yields with 61-91% ee. With BocO as reaction partner, the organocatalytic enantioselective -acylation of 2-amino-3-subsituted indoles was established to furnish C-N axially chiral products in 22-98% yields with 73-92% ee.
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