Synthesis of Benzazepines Bearing Three Contiguous Carbon Stereocenters through Pd(II)-Catalyzed [3 + 2] Cycloaddition of N-Aryl Nitrones with Allenoates

The Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 24, 2025

A cascade reaction of Pd(II)/dppben-catalyzed [3 + 2] cycloaddition N-aryl nitrones with allenoates and sequential reduction has been developed for the synthesis functionalized benzazepines bearing three contiguous carbon stereocenters in moderate to good yields ranging from 15 82% high diastereoselectivity. The obtained could be converted into various benzazepine scaffolds, an estrone-derived scaffold was prepared over four steps estrone. More importantly, chiral 88% ee value auxiliary.

Language: Английский

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Selective 6π‐Electrocyclization of N‐Vinyl‐α,β‐Unsaturated Nitrones to Prepare Polysubstituted Pyridine Derivatives

Chinese Journal of Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 7, 2025

Comprehensive Summary Herein, we have developed a facile method for the synthesis of various polysubstituted pyridine derivatives through selective 6π‐electrocyclization N ‐vinyl‐ α , β ‐unsaturated nitrones. It was found that gold catalysts promoted carbon‐6π‐electrocyclization nitrones to afford 6‐alkenyl ‐oxides in 43%—75% yields, whereas copper facilitated oxygen‐6π‐electrocyclization give 6‐epoxy pyridines 41%—83% yields. The present features broad substrate scope, good functional group tolerance, high cyclization selectivity, and diversity scaffolds.

Language: Английский

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Nickel(II)-Catalyzed Unexpected [3 + 2] Cycloaddition/[3,3]-Rearrangement of N-Vinyl α,β-Unsaturated Nitrones with 2-Alkynyl Quinazolinones

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: May 15, 2025

A nickel(II)-catalyzed unexpected [3 + 2] cycloaddition/[3,3]-rearrangement cascade reaction was developed for the preparation of various polysubstituted 1-pyrroline-tethered quinazolinones containing three contiguous stereocenters in moderate to good yields with high diastereoselectivity from N-vinyl cinnamaldehyde nitrones and 2-alkynyl quinazolinones. Polysubstituted pyrrolizine-tethered were obtained when replaced by chalcone nitrones. The present method features a broad substrate scope, [3,3]-rearrangement selectivity diastereoselectivity, two substituent bifurcated types N-heterocycles.

Language: Английский

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Yb(OTf)₃‐Catalyzed Asymmetric [3+3] Cycloaddition of N‐Vinyl Nitrones with Activated Cyclopropanes to Prepare 1,2‐Oxazines

Chinese Journal of Chemistry, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 25, 2024

Comprehensive Summary We described a Yb(OTf) 3 combined with Pybox ligand catalyzed asymmetric [3+3] cycloaddition of N ‐vinyl cinnamaldehyde nitrones activated cyclopropanes to prepare various functionalized 1,2‐oxazines in 24%—95% yields and 22%—96% ee. Experimental results revealed that the reaction underwent domino cycloaddition, dealkenylation, aza‐1,4‐addition three steps. The chiral 1,2‐oxazine could be obtained gram scales easily converted into scaffolds. present method features broad substrate scope, good functional group compatibility, three‐component reaction, cyclopropanes.

Language: Английский

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Nitrogenation of Alkynes with Nitrones to Prepare Functionalized [1,4]Oxazinones through Csp–Csp² Bond Cleavage

Organic Letters, Journal Year: 2024, Volume and Issue: 26(44), P. 9541 - 9546

Published: Oct. 25, 2024

Herein, we report a novel strategy of hypervalent iodine(III) compound-mediated selective Csp–Csp2 bond cleavage alkynes and C═N/N–O nitrones recombination C–C/C–O/C–N multiple bonds to access various functionalized [1,4]oxazinones bearing vicinal carbon stereocenter in good yields high diastereoselectivity. Mechanistic studies revealed that the reaction undergoes domino [4 + 3] cycloaddition, 1,3-rearrangement N–O bond, intramolecular cyclization, dearomatization, rearomatization over four steps single flask. The present method features functional group tolerance, broad substrate scope, C–C/C═N/N–O recombination.

Language: Английский

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