4-hydroxypiperidines containing a quaternary stereocenter by aza-Prins cyclization

Organic & Biomolecular Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

The diastereoselective synthesis of 4-hydroxypiperidines bearing a tetrasubstituted carbon stereocenter at C4 by aza-Prins cyclization is presented. These motifs are relevant because they present in considerable number drugs.

Language: Английский

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Asymmetric Synthesis of Spirooxindole Lactones by Ammonium-tethered Chiral Organocatalysts catalyzed Michael Addition/Cyclization of 3- hydroxyoxindoles with α,β-unsaturated Aldehydes

Current Catalysis, Journal Year: 2023, Volume and Issue: 12(1), P. 34 - 42

Published: April 1, 2023

Abstract: The ammonium-tethered pyrrolidine-based organocatalyst catalyzed asymmetric Michael addition/cyclization reaction of α,β-unsaturated aldehydes with 3-hydroxyoxindole in aqueous media was developed, giving the spirooxidole lactones high yields enantioselectivities. Background: 3-hydroxyoxindoles α,β- unsaturated is an important method for synthesis chiral spirooxindole derivatives, which are found a wide range biologically active natural products and pharmaceutical agents. Objective: Organocatalyzed reactions one most powerful effective approaches construction complex molecules from relatively simple starting materials. However, major problem associated these organocatalytic system that catalyst loading organic solvents required. In present work, our objective to develop water-compatible aimed at lowering being system. Methods: typical experiment, To solution 2a (0.008 mmol) PhCO2H (0.096 0.5 mL mixture solvent iPrOH/H2O (1:3) added aldehyde (0.4 (0.8 mmol). proceeded room temperature 16 hours, then extracted 10 dichloromethane give cyclized hemiacetal, subjected direct oxidation pyridinium chlorochromate (PCC, 1.2 hours desired lactones. Results: successfully gave excellent (81-95%) moderate enantioselectivities (up 99% ee). diastereoselectivities were poor ranging 1:1.1 1:2.3. Conclusion: using has been developed. performed low (2 mol%) provided (ee: up 99%).

Language: Английский

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Aza‐Prins Cyclization on Ketones to Access Piperidines with Tetrasubstituted Carbon Stereocenters

Advanced Synthesis & Catalysis, Journal Year: 2023, Volume and Issue: 366(1), P. 31 - 35

Published: Nov. 22, 2023

Abstract The aza‐Prins cyclization in presence of a variety aliphatic, aromatic, and heterocyclic ketones is disclosed. developed method allows an access to diverse C‐2 functionalized piperidines, bearing tetrasubstituted or spiranic carbon stereocenter, range 30 87% yields. When diastereomers were formed, the trans isomer was identified as major product.

Language: Английский

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Synthesis of 1,2-Dicarbonyls from Five-Membered Cyclic Enamines and Arylglyoxal Hydrates under Metal-Free Conditions

Heterocycles, Journal Year: 2023, Volume and Issue: 106(4), P. 664 - 664

Published: Jan. 1, 2023

Language: Английский

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Carbonyl and Imine Ene Reactions, Prins Reactions and Cyclizations, and Lewis Acid–Catalyzed Carbonyl Olefin Metathesis

Elsevier eBooks, Journal Year: 2023, Volume and Issue: unknown

Published: Jan. 1, 2023

Language: Английский

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