[2+2+2] Cycloadditions

Elsevier eBooks, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

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C–Halogen Bond Activation by Ruthenium(0): Application in Synthesis and Catalysis

Inorganic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 2, 2025

Activation of the C-X (X = I, Br, Cl) bond in four N-aryl benzaldimine ligands (L1-L4), bearing halogen atoms at both ortho-positions phenyl ring fragment, was successfully brought about via interaction these with electron-rich Ru(0) center [Ru(CO)3(PPh3)2], leading to formation cyclometalated complexes ruthenium(II) (C1-C4). Crystal structures all were determined. The demonstrated ability [Ru(CO)3(PPh3)2] activate C-halogen also exploited catalytic Suzuki-type C-C cross-coupling reactions between aryl halides and boronic acids.

Language: Английский

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Catalytic Schmittel-Type [2+2] Cycloaddition of γ-Alkynyl Diazoacetates with Terminal Alkynes for Accessing Cyclobuta[a]indenes

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

Published: March 17, 2025

Instead of the conventional [4+2] cycloaddition, a regioselective Schmittel-type [2+2] cycloaddition yne–allene esters, generated in situ from copper-catalyzed dediazotized coupling γ-alkynyl diazoacetates with terminal alkynes, is reported, enabling bicyclization process to produce diverse array C1-arylated cyclobuta[a]indenes moderate good yields. The protocol features wide functional group compatibility, mild reaction conditions, and experimental simplicity, holding significant potential for building new tricyclic cyclobutenes.

Language: Английский

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Direct Access to Furan and Cyclopropane Derivatives by Palladium-Catalyzed C-H Activation/Alkenes Insertion/Annulation

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(53), P. 6769 - 6772

Published: Jan. 1, 2024

A practical and effective palladium-catalyzed C-H activation/alkene insertion/annulation has been reported for the synthesis of furans cyclopropanes from cyclic 1,3-diketones or 1,3-indandione diverse alkenes, resulting in moderate to good yields. This protocol demonstrates excellent selectivity is well-compatible with a wide range alkene substrates, exhibiting exceptional regioselectivities, high efficiency, functional group tolerance.

Language: Английский

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Enantioselective Total Synthesis of (+)-Heilonine

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(40), P. 16394 - 16400

Published: Sept. 29, 2021

Chemical transformations that rapidly and efficiently construct a high level of molecular complexity in single step are perhaps the most valuable total synthesis. Among such is transition metal catalyzed [2 + 2 2] cycloisomerization reaction, which forges three new C–C bonds one or more rings synthetic operation. We report here strategy leverages this transformation to open de novo access Veratrum family alkaloids. The highly convergent approach described herein includes (i) enantioselective synthesis diyne fragment containing steroidal A/B rings, (ii) asymmetric propargyl-substituted piperidinone (F ring) unit, (iii) high-yielding union above fragments, (iv) intramolecular reaction resulting carbon framework remaining (C/D/E) hexacyclic cevanine skeleton. Efficient late-stage maneuvers culminated first heilonine (1), achieved 21 steps starting from ethyl vinyl ketone.

Language: Английский

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Cycloaddition of Cyclopropenes with Alkynes via Carbon–Carbon Double Bond Cleavage Enabled by a Ruthenium Catalyst: Synthesis of Cyclopentadienes and Cycloheptatrienes

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(14), P. 9656 - 9666

Published: July 10, 2023

Transition-metal-mediated carbon–carbon single-bond cleavage of cyclopropenes has been widely exploited in organic synthesis. However, the ring-opening via their double bond remains a formidable challenge. Herein, we report an intramolecular cycloaddition with alkynes enabled by ruthenium catalyst to afford 1,2-fused cyclopentadienes, which are difficult access conventional synthetic methods. Density functional theory calculations indicate that reaction proceeds cyclopropane-fused ruthenacycle undergoes ring expansion generate six-membered cyclic biscarbenoid. We also synthesized fused cycloheptatrienes cyclopropene–diynes.

Language: Английский

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Dibenzocycloheptanones construction through a removable P-centered radical: synthesis of allocolchicine analogues

Chemical Science, Journal Year: 2021, Volume and Issue: 12(47), P. 15727 - 15732

Published: Jan. 1, 2021

Dibenzocycloheptanones containing a tricyclic 6–7–6-system are present in numerous biologically active natural molecules.

Language: Английский

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Recent Advances for the Construction of Seven-Membered Ring Catalyzed by N-Heterocyclic Carbenes

Chinese Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 42(4), P. 925 - 925

Published: Jan. 1, 2022

The seven-membered rings represent an important structural motif and have found wide presence in natural products, biologically active molecules drugs.In contrast to the five-and six-membered rings, construction of sevenmembered ring remains challenging.Thus, developing efficient strategies for synthesis is very desirable.N-Heterocyclic carbene (NHC) organocatalysis has been recognized as a powerful unique tool quick complex molecular architectures.Nevertheless, whereas significant advances made using NHC catalysis.However, most these works concentrated on assembly five or rings.This review highlights developments new catalyzed by NHC.The aim this provide overview area inspire synthetic chemists develop more novel rings.

Language: Английский

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Nickel‐Catalyzed Hydroborylative Polycyclization of Allenynes: an Atom‐Economical and Diastereoselective Synthesis of Bicyclic 5‐5 Fused Rings

Advanced Synthesis & Catalysis, Journal Year: 2022, Volume and Issue: 364(10), P. 1716 - 1723

Published: Feb. 26, 2022

Abstract A diastereoselective synthesis of borylated bicyclic 5‐5 fused ring systems by a domino Ni‐catalyzed hydroborylative polycyclization allenynes has been developed. The reaction provides two new C−C and one C−B bonds constitutes an atom‐economical method. It occurs rapidly, in absence inert atmosphere, with inexpensive Ni‐based catalyst HBpin as boron source. procedure showed excellent tolerance to functional groups wide scope. Derivatization the bicycles performed explore synthetic utility products. Experimental DFT‐calculation results suggest that process starts oxidative cyclometallation involving Ni(0) both allene alkyne moieties, followed stereoselective σ‐metathesis HBpin. Formation second takes place through non‐fully coplanar 1,2‐insertion into Ni−H bond give nickelacyclohexene which finally evolves reductive elimination. magnified image

Language: Английский

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Hetero Diels-Alder reactions of isolable N-borylenamines

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(46), P. 5964 - 5967

Published: Jan. 1, 2024

A new strategy for

Language: Английский

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