Asymmetric Synthesis of Spiropyrazolones via Chiral Pd(0)/Ligand Complex-Catalyzed Formal [4+2] Cycloaddition of Vinyl Benzoxazinanones with Alkylidene Pyrazolones

The Journal of Organic Chemistry, Journal Year: 2020, Volume and Issue: 86(2), P. 1712 - 1720

Published: Dec. 30, 2020

In the presence of chiral Pd(0)/ligand complex, vinyl benzoxazinanones underwent [4+2] cycloaddition with alkylidene pyrazolones smoothly and delivered spiropyrazolones in reasonable yields, diastereoselectivities, eneantioselectivities (up to >99% yield, >99:1 dr 99% ee). The absolute configuration obtained was unambiguously characterized use X-ray single-crystal structure analysis. Moreover, reaction mechanism assumed interpret formation target compounds.

Language: Английский

---

Recent Advances in Catalytic Enantioselective Synthesis of Pyrazolones with a Tetrasubstituted Stereogenic Center at the 4-Position

Synthesis, Journal Year: 2020, Volume and Issue: 53(02), P. 215 - 237

Published: Oct. 8, 2020

Abstract Pyrazolone [2,4-dihydro-3H-pyrazol-4-one] represents one of the most important five-membered nitrogen heterocycles which is present in numerous pharmaceutical drugs and molecules with biological activity. Recently, many catalytic methodologies for asymmetric synthesis chiral pyrazolones have been established great success, specially, bearing a tetrasubstituted stereocenter at C-4. This review summarizes these excellent research studies since 2018, including representative examples some mechanistic pathways explaining observed stereochemistry. 1 Introduction 2 Catalytic Enantioselective Synthesis Chiral Pyrazolones Full Carbon Tetrasubstituted Stereocenter C-4 3 Quaternary Heteroatom 4 Spiropyrazolones 5 Conclusion

Language: Английский

---

Organo-catalyzed asymmetric cascade annulation reaction for the construction of bi-spirocyclic pyrazolone and oxindole derivatives

Organic Chemistry Frontiers, Journal Year: 2020, Volume and Issue: 7(5), P. 796 - 809

Published: Jan. 1, 2020

Organo-catalyzed tandem reaction between β,γ-unsaturated α-ketoesters and α-arylidene pyrazolinones was developed, it provided chiral bi-spirocyclic pyrazolone oxindole derivatives in high yields with good to excellent stereoselectivity.

Language: Английский

---

Umpolung Strategy for the Synthesis of Chiral Dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles

The Journal of Organic Chemistry, Journal Year: 2020, Volume and Issue: 85(12), P. 7793 - 7802

Published: May 29, 2020

Based on a novel umpolung strategy, an efficient and highly enantioselective cascade aldol/cyclization/tautomerization of the 2-(2-oxoindolin-3-yl)malononitrile to active carbonyl compounds with excellent diastereo- enantioselectivity has been developed. Also, various enantio-enriched multifunctional dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles adjacent spiro-stereocenters were conveniently obtained by this methodology. easily transformed into structurally complex molecules without any effect enantioselectivity.

Language: Английский

---

Squaramide Catalyzed Asymmetric Synthesis of Five‐ and Six‐Membered Rings

Asian Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 10(6), P. 1345 - 1376

Published: April 19, 2021

Abstract Chiral analogues of squaramides have been fruitful in organocatalyzed asymmetric reactions over last decade. Alongside other H‐bonding catalysts like ureas, thioureas: proved to be efficient for the formation acyclic and cyclic chiral molecules. A wide range molecules bearing multiple functionalities stereocenters synthesized by using several bifunctional as catalysts. These perform base utilizing basic N atom their extension help stereoinduction forming H‐bonds with suitable H‐bond acceptors. The present review focuses on assembling recent progresses synthesis five six membered rings promoted squaramides. handful articles published research groups documenting construction five‐ six‐membered part interesting complex molecular architectures. Different methodologies conventional formal cycloadditions or cascade engineered through assistance fabricate carbo‐ heterocycles. This also includes dual cooperative catalytic system which squaramide is one

Language: Английский

---

Concise Synthesis of Spirocyclic Dihydrophthalazines through Spiroannulation Reactions of Aryl Azomethine Imines with Cyclic Diazo Compounds

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(16), P. 11048 - 11062

Published: Aug. 3, 2022

Spiroannulation reactions are fundamental and invaluable for the synthesis of spirocyclic compounds. Presented herein novel cascade aryl azomethine imines with cyclic diazo compounds leading to formation dihydrophthalazine derivatives. Based on experimental mechanistic studies, title products is believed go through imine-assisted cylcometalation, Rh-carbene dediazonization, migratory insertion followed by reductive elimination imine ring opening. Control experiments revealed that air acts as an effective sustainable co-oxidant facilitate reaction. In general, this concise unprecedented derivatives has advantages such easily accessible substrates, good functional group compatibility, mild reaction conditions, high efficiency selectivity, excellent atom-economy. addition, value protocol underlined its ready scalability divergent derivation products.

Language: Английский

---

Enantioselective Synthesis of Multisubstituted Spirocyclopentane Oxindoles Enabled by Pd/Chiral Rh(III) Complex Synergistic Catalysis

Organic Letters, Journal Year: 2020, Volume and Issue: 22(24), P. 9539 - 9544

Published: Dec. 2, 2020

An asymmetric [3 + 2]-cycloaddition reaction of α,β-unsaturated 2-acyl imidazoles with spirovinylcyclopropanyl-2-oxindoles catalyzed synergistically by an achiral palladium(0) catalyst and a chiral-at-metal rhodium(III) complex has been developed. A series biologically important 3-spirocyclopentane-2-oxindoles four contiguous stereocenters were synthesized in high yields (up to 99%) excellent stereoselectivities 99% ee, 20:1 dr).

Language: Английский

---

Asymmetric Synthesis of Spirocyclopentane Oxindoles via [2+3] Annulation with 2‐(2‐Oxoindolin‐3‐yl)malononitriles as 1,2‐Carbon Bisnucleophiles

Advanced Synthesis & Catalysis, Journal Year: 2021, Volume and Issue: 363(13), P. 3283 - 3289

Published: April 23, 2021

Abstract Carbon bisnucleophiles are important building blocks in organic synthesis and have widespread applications the construction of carbocyclic compounds. Among them, 1,2‐carbon bisnucleophile has been much less explored. Herein, we developed a [2+3] annulation 2‐(2‐oxoindolin‐3‐yl)malononitrile with 2‐nitroallylic acetates, where served as new type bisnucleophile. Remarkably, reaction exhibits exclusive chemo‐ regioselectivity. A Michael addition/S N 2 mechanism was proposed to avoid “anti‐Baldwin” cyclization. This stereoselective strategy provides facile synthetic route for series spirocyclopentane oxindole derivatives containing three stereogenic centers. magnified image

Language: Английский

---

Direct access to spirooxindole dihydropyrrole fused pyrazolones and bis-spiropyrazolone derivatives

Tetrahedron Letters, Journal Year: 2022, Volume and Issue: 97, P. 153791 - 153791

Published: April 14, 2022

Language: Английский

---

Organocatalytic Asymmetric Synthesis of Spirooxindole Embedded Oxazolidines

The Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 86(18), P. 13082 - 13091

Published: Aug. 27, 2021

The first organocatalytic asymmetric synthesis of spirooxindole embedded oxazolidines has been developed via a domino reaction involving hemiaminal formation, followed by an unprecedented aza-Michael between isatin derived N-Boc ketimines and γ-hydroxy enones. A quinine bifunctional squaramide catalyst was found to be efficient for this reaction, the products were obtained in good diastereoselectivity with high enantioselectivity.

Language: Английский

---