Diastereo- and Enantioselective Synthesis of Eight-Membered Heterocycles via an Allylation/Ring Expansion Sequence Enabled by Multiple Catalysis

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(20), P. 12557 - 12564

Published: Sept. 29, 2021

The development of protocols for constructing chiral medium-sized heterocycles with high efficiency and excellent stereocontrol is great interest owing to their ubiquitous occurrence in natural products biologically active pharmaceuticals. Nonetheless, current synthetic approaches are limited due unfavorable enthalpy entropy factors, as well transannular interactions. present work addresses this issue by designing an asymmetric allylation/ring expansion reaction 2-(1-hydroxyallyl)phenols cyclobutanone carboxamides enabled sequential iridium/zinc/bifunctional squaramide catalysis, affording a series 8-membered benzo[b]oxocines yields diastereo- enantioselectivities. Mechanistic investigation reveals that the enantioselectivity controlled iridium catalyst, while density functional theory calculations demonstrate diastereoselectivity bifunctional catalyst. Moreover, allylation strategy demonstrated be also applicable synthesis two types enantiomerically enriched nitrogen heterocycles, benzo[b]azocines polycyclic cyclobuta[b]quinolines.

Language: Английский

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Diastereo‐ and Enantioselective Synthesis of Bisbenzannulated Spiroketals and Spiroaminals by Ir/Ag/Acid Ternary Catalysis

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(42)

Published: Aug. 4, 2022

Abstract We reported herein an iridium/silver/acid ternary catalytic system to access bisbenzannulated [6,6]‐spiroketals in high efficiency with generally diastereo‐ and enantioselectivities (up >20 : 1 dr, >99 % ee). In this procedure, readily available o ‐alkynylacetophenones undergo cycloisomerization generate isochromenes situ that participate stereoselective allylation/spiroketalization sequence 2‐(1‐hydroxyallyl)phenols. Meanwhile, 2‐(1‐hydroxyallyl)anilines were also compatible cascade reaction, furnishing structurally novel [6,6]‐spiroaminals good diastereoselectivities (8 1–12 dr) excellent (98 %–>99 Moreover, experimental studies theoretical calculations performed illustrate the reaction mechanism stereochemistry.

Language: Английский

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Enantioselective Dearomatization of Indoles via SmI₂-Mediated Intermolecular Reductive Coupling with Ketones

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(18), P. 10314 - 10321

Published: April 26, 2023

Samarium diiodide (SmI2) mediated reductive coupling reactions are powerful methods for the construction of carbon-carbon bond in organic synthesis. Despite extensive development recent decades, successful examples corresponding asymmetric remained scarce, probably due to involvement highly reactive radical intermediates. In this Article, we report an enantioselective dearomatization indoles via SmI2-mediated intermolecular with ketones. The utilization samarium reductant supported by chiral tridentate aminodiol ligands allows facile synthesis indoline molecules bearing two contiguous stereogenic centers high yields (up 99%) and stereoselectivity 99:1 er >20:1 dr). Combined experimental computational investigations suggested that parallel single-electron transfer each substrate from radical-radical recombination manner, which is a unique mechanistic scenario reactions.

Language: Английский

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Enantioselective dearomative [3+2] cycloaddition of 2-nitrobenzofurans with aldehyde-derived Morita–Baylis–Hillman carbonates

Chemical Communications, Journal Year: 2019, Volume and Issue: 55(62), P. 9144 - 9147

Published: Jan. 1, 2019

The phosphine-catalyzed asymmetric dearomative [3+2] cycloaddition of 2-nitrobenzofurans with aldehyde-derived Morita-Baylis-Hillman (MBH) carbonates or allenoate was developed. reaction MBH resulted in a series cyclopentabenzofurans containing three contiguous stereocenters good to high yields, diastereoselectivities and enantioselectivities. use also gave the target product moderate enantioselectivity.

Language: Английский

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Non-monoterpenoid azepinoindole alkaloids

Natural Product Reports, Journal Year: 2018, Volume and Issue: 35(12), P. 1347 - 1382

Published: Jan. 1, 2018

This review discusses various biological and chemical aspects of the non-monoterpenoid azepinoindole class alkaloids, including their isolation, biosynthesis total synthesis.

Language: Английский

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