scholarly journals Pd-catalyzed asymmetric Suzuki–Miyaura coupling reactions for the synthesis of chiral biaryl compounds with a large steric substituent at the 2-position

2020 ◽  
Vol 16 ◽  
pp. 966-973
Author(s):  
Yongsu Li ◽  
Bendu Pan ◽  
Xuefeng He ◽  
Wang Xia ◽  
Yaqi Zhang ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Coupling Reactions ◽  
Mild Conditions ◽  
Axially Chiral ◽  
High Yields ◽  
Very High ◽  
Significant Superiority ◽  
Biaryl Compounds

Pd-catalyzed asymmetric Suzuki–Miyaura couplings of 3-methyl-2-bromophenylamides, 3-methyl-2-bromo-1-nitrobenzene and 1-naphthaleneboronic acids have been successfully developed and the corresponding axially chiral biaryl compounds were obtained in very high yields (up to 99%) with good enantioselectivities (up to 88% ee) under mild conditions. The chiral-bridged biphenyl monophosphine ligands developed by our group exhibit significant superiority to the naphthyl counterpart MOP in both reactivity and enantioselectivity control. The large steric hindrance from π-conjugated ortho-substituents of the bromobenzene substrates and the Pd···O interaction between carbonyl and palladium seem essential to achieve high enantioselectivity.

Copper(II)-Catalyzed C–N Coupling of Aryl Halides and N-Nucleophiles Promoted by Quebrachitol or Diethylene Glycol

Synlett ◽  
2019 ◽  
Vol 30 (19) ◽  
pp. 2161-2168
Author(s):  
Fangyu Du ◽  
Qifan Zhou ◽  
Yang Fu ◽  
Yuanguang Chen ◽  
Ying Wu ◽  
...  
Keyword(s):  
Diethylene Glycol ◽  
Functional Group ◽  
Aryl Halides ◽  
Coupling Reactions ◽  
Mild Conditions ◽  
Natural Ligand ◽  
Highly Effective ◽  
High Yields

Herein, we report the natural ligand quebrachitol (QCT) as a promoter for a Cu(II) catalyst, which is highly effective for N-arylation of various amines and related aryl halides. A series of diarylamine derivatives were obtained in high yields by using diethylene glycol (DEG) as both ligand and solvent. The C–N coupling reactions proceed under mild conditions and exhibit good functional group tolerance.

Palladium-catalyzed Suzuki cross-couplings of N′-mesyl arylhydrazines via C–N bond cleavage

RSC Advances ◽  
2014 ◽  
Vol 4 (49) ◽  
pp. 25576-25579 ◽  
Author(s):  
He-Ping Zhou ◽  
Jin-Biao Liu ◽  
Jian-Jun Yuan ◽  
Yi-Yuan Peng
Keyword(s):  
Boronic Acid ◽  
Bond Cleavage ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Mild Conditions ◽  
Cross Coupling Reaction ◽  
Palladium Catalyzed ◽  
High Yields ◽  
Aryl Boronic Acid ◽  
Biaryl Compounds

An efficient palladium-catalyzed Suzuki cross-coupling reaction of N′-mesyl arylhydrazine with aryl boronic acid is described, which affords the corresponding biaryl compounds in high yields. This transformation proceeds through C–N bond cleavage under mild conditions.

Cu(II)/vasicine promoted intramolecular C-O formation: synthesis of benzoxazoles in EtOH

2020 ◽  
Vol 17 ◽  
Author(s):  
Minxin Li ◽  
Meiling Li ◽  
Yanling Tang ◽  
Yun Sun ◽  
Lu Qu ◽  
...  
Keyword(s):  
Catalytic System ◽  
Aromatic Compounds ◽  
Bond Formation ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Mild Conditions ◽  
Cross Coupling Reactions ◽  
High Yields

Aim and Objective: Benzoxazoles are valuable bicyclic aromatic compounds, the construction of benzoxazoles via C-O cross-coupling reactions has attracted more and more attention. Materials and Methods: The best condition of C-O bond formation from o-haloanilides was carried out taking Cu(OTf)2 (5 mol%) and vasicine (10 mol%) as the catalyst in EtOH in present of K2CO3 (2 eq.) for 12 h at 90oC. Results: A series of 2-substituted benzoxazoles have been prepared in high yields from 2-bromoanilides and 2-iodioanilides under mild conditions. Conclusion: We have developed an efficient Cu-vasicine catalytic system for intramolecular C-O bond formation. This strategy is applicable to synthesis of a wide variety of 2-substituted benzoxazoles by intramolecular O-arylation of o-haloanilides.

Novel cyclization and reductive coupling of bicyclic olefins with alkyl propiolates catalyzed by nickel complexes

2002 ◽  
Vol 74 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Dinesh Kumar Rayabarapu ◽  
Chien-Hong Cheng
Keyword(s):  
Nickel Complex ◽  
Room Temperature ◽  
Nickel Complexes ◽  
Coupling Reaction ◽  
Coupling Reactions ◽  
Reductive Coupling ◽  
Mild Conditions ◽  
Reaction Proceeds ◽  
High Yields ◽  
Alkyl Propiolates

In this article, new metal-mediated cyclization and reductive coupling reactions of bicyclic olefins with alkynes are described. Oxabicyclic alkenes undergo cyclization with alkyl propiolates at 80 C catalyzed by nickel complexes to give benzocoumarin derivatives in high yields. The reaction of bicyclic alkenes (oxa- and azacyclic alkenes) with alkyl propiolates at room temperature in the presence of the same nickel complex gave 1,2-dihydro-napthelene derivatives in good-to-excellent yields. This reductive coupling reaction proceeds under very mild conditions in complete regio- and stereoselective fashion. A mechanism to account for the coumarin formation and the reductive coupling is proposed.

scholarly journals A versatile Diels–Alder approach to functionalized hydroanthraquinones

2020 ◽  
Vol 7 (11) ◽  
pp. 200626
Author(s):  
Janina Beck ◽  
Olaf Fuhr ◽  
Martin Nieger ◽  
Stefan Bräse
Keyword(s):  
Natural Product ◽  
Alder Reaction ◽  
Diels Alder ◽  
Coupling Reactions ◽  
Ring Systems ◽  
Mild Conditions ◽  
Diels Alder Reaction ◽  
High Yields

The synthesis of highly substituted hydroanthraquinone derivatives with up to three stereogenic centres via a Diels–Alder reaction, starting from easily accessible 2-substituted naphthoquinones, is described. The [4+2]-cycloaddition is applicable for a broad range of substrates, runs under mild conditions and results in high yields. The highly regioselective outcome of the reactions is enabled by a benzoyl substituent at C2 of the dienophiles. The obtained hydroanthraquinones can be further modified and represent ideal substrates for follow-up intramolecular coupling reactions to create unique bicyclo[3.3.1] or -[3.2.2]nonane ring systems which are important natural product skeletons.

scholarly journals Efficient Electrochemical N-Alkylation of N-Boc-Protected 4-Aminopyridines: Towards New Biologically Active Compounds

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Marta Feroci ◽  
Isabella Chiarotto ◽  
Gianpiero Forte ◽  
Giovanna Simonetti ◽  
Felicia Diodata D'Auria ◽  
...  
Keyword(s):  
High Reactivity ◽  
Alkyl Halides ◽  
Biologically Active ◽  
Direct Reaction ◽  
Antiprotozoal Activity ◽  
Subsequent Reaction ◽  
Mild Conditions ◽  
High Yields ◽  
By Products ◽  
Very High

The use of electrogenerated acetonitrile anion allows the alkylation of N-Boc-4-aminopyridine in very high yields, under mild conditions and without by-products. The high reactivity of this base is due to its large tetraethylammonium counterion, which leaves the acetonitrile anion “naked.” The deprotection of the obtained compounds led to high yields in N-alkylated 4-aminopyridines. Nonsymmetrically dialkylated 4-aminopyridines were obtained by subsequent reaction of monoalkylated ones with t-BuOK and alkyl halides, while symmetrically dialkylated 4-aminopyridines were obtained by direct reaction of 4-aminopyridine with an excess of t-BuOK and alkyl halides. Some mono- and dialkyl-4-aminopyridines were selected to evaluate antifungal and antiprotozoal activity; the dialkylated 4-aminopyridines 3ac, 3ae and 3ff showed antifungal towards Cryptococcus neoformans; whereas 3cc, 3ee and 3ff showed antiprotozoal activity towards Leishmania infantum and Plasmodium falciparum.

scholarly journals Efficient Production of Poly(Cyclohexene Carbonate) via ROCOP of Cyclohexene Oxide and CO2 Mediated by NNO-Scorpionate Zinc Complexes

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2148
Author(s):  
Sonia Sobrino ◽  
Marta Navarro ◽  
Juan Fernández-Baeza ◽  
Luis F. Sánchez-Barba ◽  
Agustín Lara-Sánchez ◽  
...  
Keyword(s):  
Ring Opening ◽  
Zinc Complexes ◽  
Efficient Production ◽  
Cyclohexene Oxide ◽  
X Ray Diffraction ◽  
Co Catalyst ◽  
X Ray ◽  
Mild Conditions ◽  
High Yields ◽  
Very High

New mono- and dinuclear chiral alkoxide/thioalkoxide NNO-scorpinate zinc complexes were easily synthesized in very high yields, and characterized by spectroscopic methods. X-ray diffraction analysis unambiguously confirmed the different nuclearity of the new complexes as well as the variety of coordination modes of the scorpionate ligands. Scorpionate zinc complexes 2, 4 and 6 were assessed as catalysts for polycarbonate production from epoxide and carbon dioxide with no need for a co-catalyst or activator under mild conditions. Interestingly, at 70 °C, 10 bar of CO2 pressure and 1 mol % of loading, the dinuclear thioaryloxide [Zn(bpzaepe)2{Zn(SAr)2}] (4) behaves as an efficient and selective one-component initiator for the synthesis of poly(cyclohexene carbonate) via ring-opening copolymerization of cyclohexene oxide (CHO) and CO2, affording polycarbonate materials with narrow dispersity values.

An Iron-Based Catalyst Enables The Enantioconvergent Synthesis of Chiral 1,1-Diarylalkanes Through a Suzuki-Miyaura Cross-Coupling Reaction

2020 ◽  
Author(s):  
Chet Tyrol ◽  
Nang Yone ◽  
Connor Gallin ◽  
Jeffery Byers
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Radical Intermediates ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Boronic Esters ◽  
Carbon Centered Radical ◽  
Iron Based ◽  
High Yields

By using an iron-based catalyst, access to enantioenriched 1,1-diarylakanes was enabled through an enantioselective Suzuki-Miyaura crosscoupling reaction. The combination of a chiral cyanobis(oxazoline) ligand framework and 1,3,5-trimethoxybenzene additive were essential to afford high yields and enantioselectivities in cross-coupling reactions between unactivated aryl boronic esters and a variety of benzylic chlorides, including challenging ortho-substituted benzylic chloride substrates. Mechanistic investigations implicate a stereoconvergent pathway involving carbon-centered radical intermediates.

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