scholarly journals Gold(I)-Catalyzed Tandem Synthesis of Polycyclic Dihydroquinazolinones

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1436
Author(s):  
Jingyang Sun ◽  
Yoona Song ◽  
Jae-Sang Ryu
Keyword(s):  
Gold Catalysts ◽  
Catalyst System ◽  
Membered Ring ◽  
Cascade Process ◽  
Tandem Synthesis

A gold-catalyzed cascade process for the synthesis of dihydroquinazolinone scaffolds was developed. A series of gold catalysts were screened for this tandem transformation, and the (PPh3)AuCl/AgOTf catalyst combination was found to be the best catalyst system. This method is characterized by good yields, high regioselectivity, and broad substrate scope. This method is also applicable to the synthesis of tetracyclic dihydroquinazolinones and seven-membered ring-fused dihydroquinazolinones.

Annulation of Indoles with 1,n-Dibromoalkanes by a Pd(II)-Catalyzed and Norbornene-Mediated Reaction Cascade

Synthesis ◽  
2019 ◽  
Vol 52 (08) ◽  
pp. 1231-1238 ◽  
Author(s):  
Michael Henkel ◽  
Thorsten Bach
Keyword(s):  
Direct Synthesis ◽  
Membered Ring ◽  
Ring Formation ◽  
Cascade Process

Employing 1,3-dibromopropane, 1,4-dibromobutane, and 1,5-dibromopentane as biselectrophiles, the annulation of indoles was probed in the presence of PdCl2(MeCN)2 as a catalyst and norbornene as a transpositional ligand. Ring formation to a five-membered ring was observed at positions C2 and N, while annulation of a six-membered ring occurred at positions C2 and C3. The latter cascade process was successfully applied to the direct synthesis of 1,2,3,4-tetrahydrocarbazoles from indoles (11 examples, 31–68% yield). Seven-membered-ring annulation was feasible by an initial coupling at positon C2 followed by alkylation at C3.

scholarly journals Stereodivergent assembly of tetrahydro-γ-carbolines via synergistic catalytic asymmetric cascade reaction

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shi-Ming Xu ◽  
Liang Wei ◽  
Chong Shen ◽  
Lu Xiao ◽  
Hai-Yan Tao ◽  
...  
Keyword(s):  
Natural Products ◽  
Structural Unit ◽  
Indole Alkaloids ◽  
Catalyst System ◽  
Cascade Reaction ◽  
Vital Role ◽  
System Control ◽  
Cascade Process ◽  
Basic Structural Unit ◽  
Stereogenic Centers

AbstractEnantiomerically enriched indole-containing heterocycles play a vital role in bioscience, medicine, and chemistry. As one of the most attractive subtypes of indole alkaloids, highly substituted tetrahydro-γ-carbolines are the basic structural unit in many natural products and pharmaceuticals. However, the syntheses of tetrahydro-γ-carbolines with high functionalities from readily available reagents are significant challenging. In particular, the stereodivergent syntheses of tetrahydro-γ-carbolines containing multi-stereogenic centers remain quite difficult. Herein, we report an expedient and stereodivergent assembly of tetrahydro-γ-carbolines with remarkably high levels of stereoselective control in an efficient cascade process from aldimine esters and indolyl allylic carbonates via a synergistic Cu/Ir catalyst system. Control experiments-guided optimization of synergistic catalysts and mechanistic investigations reveal that a stereodivergent allylation reaction and a subsequent highly stereoselective iso-Pictet-Spengler cyclization are the key elements to success.

Tandem Synthesis of N-Alkylated Amides from Aldoximes and Alcohols by Using a Ru/Ir Dual-Catalyst System

ChemCatChem ◽  
2013 ◽  
Vol 5 (8) ◽  
pp. 2178-2182 ◽  
Author(s):  
Feng Li ◽  
Panpan Qu ◽  
Juan Ma ◽  
Xiaoyuan Zou ◽  
Chunlou Sun
Keyword(s):  
Catalyst System ◽  
Tandem Synthesis

ChemInform Abstract: Tandem Synthesis of N-Alkylated Amides from Aldoximes and Alcohols by Using a Ru/Ir Dual-Catalyst System.

ChemInform ◽  
2013 ◽  
Vol 45 (1) ◽  
pp. no-no
Author(s):  
Feng Li ◽  
Panpan Qu ◽  
Juan Ma ◽  
Xiaoyuan Zou ◽  
Chunlou Sun
Keyword(s):  
Catalyst System ◽  
Tandem Synthesis

Deoxygenative coupling of nitroarenes for the synthesis of aromatic azo compounds with CO using supported gold catalysts

2015 ◽  
Vol 51 (56) ◽  
pp. 11217-11220 ◽  
Author(s):  
Hai-Qian Li ◽  
Xiang Liu ◽  
Qi Zhang ◽  
Shu-Shuang Li ◽  
Yong-Mei Liu ◽  
...  
Keyword(s):  
Gold Catalyst ◽  
Gold Catalysts ◽  
Catalyst System ◽  
Azo Compounds ◽  
Reductive Coupling ◽  
Supported Gold Catalysts ◽  
Free Gold ◽  
Aromatic Azo Compounds ◽  
Supported Gold

A simple ligand- and additive-free gold catalyst system that enables the CO-mediated reductive coupling of nitroarenes has been identified.

Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron-Electron Resonance

2019 ◽  
Author(s):  
Dennis Bücker ◽  
Annika Sickinger ◽  
Julian D. Ruiz Perez ◽  
Manuel Oestringer ◽  
Stefan Mecking ◽  
...  
Keyword(s):  
Chain Length ◽  
Length Distribution ◽  
Catalyst System ◽  
Chain Conformation ◽  
Controlled Polymerization ◽  
Chain Length Distribution ◽  
Electron Resonance ◽  
Double Electron ◽  
The Individual ◽  
Double Electron Electron Resonance

Synthetic polymers are mixtures of different length chains, and their chain length and chain conformation is often experimentally characterized by ensemble averages. We demonstrate that Double-Electron-Electron-Resonance (DEER) spectroscopy can reveal the chain length distribution, and chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura Coupling Polymerization (cSMCP). The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation and flexibility can also be accessed within poly(fluorene) nanoparticles.

An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Proton Transfer ◽  
Transition State ◽  
Lower Energy ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Ammonium Ion ◽  
Alternate Energy ◽  
Ring Transition State ◽  
Mbh Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann<i> </i>elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.

An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Proton Transfer ◽  
Transition State ◽  
Lower Energy ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Ammonium Ion ◽  
Alternate Energy ◽  
Ring Transition State ◽  
Mbh Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann<i> </i>elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.

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