Access to Substituted Indenol Ethers via a Regioselective Intermolecular Carbopalladation Cascade

2019 ◽  
Author(s):  
Brandon L. Coles-Taylor ◽  
Maximilian S. McCallum ◽  
Andrés G. Muñoz ◽  
Brian Michel
Keyword(s):  
Heck Reaction ◽  
Reductive Elimination ◽  
Catalytic Cycle ◽  
Reaction Conditions ◽  
Powerful Approach ◽  
Migratory Insertion ◽  
Ynol Ethers ◽  
Hydride Elimination ◽  
Turn Over

Alkyne carbopalladation reactions represent a powerful approach to generating multiple new C–C bonds and substituted alkenes, however regioselectivity is often challenging for intermolecular variants. By utilizing ynol ethers as polarized alkynes we observe complete regiocontrol of migratory insertion with Pd–Ar species. A Heck reaction was used to turn-over the catalytic cycle by intercepting the vinyl-Pd adduct of carbopalladation with a pendant alkene. When using <i>o</i>-iodo styrenes substrates the resulting products are oligosubstituted 1-indenol ethers with defined stereochemistry based on the initial alkene geometry. By blocking β-hydride elimination we demonstrated C–H and C–C reductive elimination steps for catalyst turnover. Herein we report the optimization of reaction conditions, scope, and alternative termination steps.

Access to Substituted Indenol Ethers via a Regioselective Intermolecular Carbopalladation Cascade

2019 ◽  
Author(s):  
Brandon L. Coles-Taylor ◽  
Maximilian S. McCallum ◽  
Andrés G. Muñoz ◽  
Brian Michel
Keyword(s):  
Heck Reaction ◽  
Reductive Elimination ◽  
Catalytic Cycle ◽  
Reaction Conditions ◽  
Powerful Approach ◽  
Migratory Insertion ◽  
Ynol Ethers ◽  
Hydride Elimination ◽  
Turn Over

Alkyne carbopalladation reactions represent a powerful approach to generating multiple new C–C bonds and substituted alkenes, however regioselectivity is often challenging for intermolecular variants. By utilizing ynol ethers as polarized alkynes we observe complete regiocontrol of migratory insertion with Pd–Ar species. A Heck reaction was used to turn-over the catalytic cycle by intercepting the vinyl-Pd adduct of carbopalladation with a pendant alkene. When using <i>o</i>-iodo styrenes substrates the resulting products are oligosubstituted 1-indenol ethers with defined stereochemistry based on the initial alkene geometry. By blocking β-hydride elimination we demonstrated C–H and C–C reductive elimination steps for catalyst turnover. Herein we report the optimization of reaction conditions, scope, and alternative termination steps.

Nickel-Catalyzed Multicomponent Coupling Reaction of Alkyl Halides, Isocyanides and H2O: An Expedient Way to Access Alkyl Amides

Synthesis ◽  
2020 ◽  
Vol 52 (22) ◽  
pp. 3466-3472
Author(s):  
Yunkui Liu ◽  
Bingwei Zhou ◽  
Qiao Li ◽  
Hongwei Jin
Keyword(s):  
Functional Group ◽  
Coupling Reaction ◽  
Alkyl Halides ◽  
Previous Literature ◽  
Catalytic Cycle ◽  
Reaction Conditions ◽  
Multicomponent Coupling ◽  
Easy Operation

We herein describe a Ni-catalyzed multicomponent coupling reaction of alkyl halides, isocyanides, and H2O to access alkyl amides. Bench-stable NiCl2(dppp) is competent to initiate this transformation under mild reaction conditions, thus allowing easy operation and adding practical value. Substrate scope studies revealed a broad functional group tolerance and generality of primary and secondary alkyl halides in this protocol. A plausible catalytic cycle via a SET process is proposed based on preliminary experiments and previous literature.

Ni(COD)(DMFU): A Heteroleptic 16-Electron Precatalyst for 1,2-Diarylation of Alkenes

Synlett ◽  
2021 ◽  
Author(s):  
Nana Kim ◽  
Van T. Tran ◽  
Omar Apolinar ◽  
Steven Wisniewski ◽  
Martin Eastgate ◽  
...  
Keyword(s):  
Nickel Complex ◽  
Active Catalyst ◽  
Cross Coupling ◽  
Reductive Elimination ◽  
Coupling Reactions ◽  
Beneficial Effects ◽  
Cross Coupling Reactions ◽  
Growing Body ◽  
Hydride Elimination

Electron-deficient olefin (EDO) ligands are known to promote a variety of nickel-catalyzed cross-coupling reactions, presumably by accelerating the reductive elimination step and preventing undesired β-hydride elimination. While there is a growing body of experimental and computational evidence elucidating the beneficial effects of EDO ligands, significant gaps remain in our understanding of the underlying coordination chemistry of the Ni–EDO species involved. In particular, most procedures rely on in situ assembly of the active catalyst, and there is a paucity of pre-ligated Ni-EDO precatalysts. Herein, we investigate the 16-electron, heteroleptic nickel complex, Ni(COD)(DMFU), and examine the performance of this complex as a precatalyst in 1,2-diarylation of alkenes.

scholarly journals Heck-Type Coupling of Fused Bicyclic Vinylcyclopropanes: Synthesis of 1,2-Dihydropyridines, 2,3-Dihydro-1H-Azepines, 1,4-Cyclohexadienes, 2H-Pyrans, and 1,3-Butadienes

2021 ◽  
Author(s):  
Nikolai Wurzer ◽  
Urszula Klimczak ◽  
Tobias Babl ◽  
Sebastian Fischer ◽  
Ricardo A. Angnes ◽  
...  
Keyword(s):  
Heck Reaction ◽  
Ring Opening ◽  
Theoretical Calculations ◽  
Ring Expansion ◽  
Mechanistic Studies ◽  
Type Coupling ◽  
Hydride Elimination ◽  
Unexpected Behavior

Herein, we report a versatile approach for the endocyclic ring-opening of bicyclic vinylcyclopropanes triggered by Heck arylations. Key step for this transformation is a [1,3]-migratory shift of Pd allowing the ring expansion of cyclopropanated pyrroles, piperidines, furans as well as cyclopentadienes to grant access to the corresponding 1,2-dihydropyridines, 2<i>H</i>-pyrans, 2,3-dihydro-1<i>H</i>-azepines and 1,4-cyclohexadienes, respectively. Additionally, <i>gem</i>-disubstituted cyclopropanated furans showed unexpected behavior by giving diastereoselectively asymmetrically substituted dienes. Mechanistic studies and theoretical calculations point towards a facile [1,3]-migratory shift of Pd along the cyclopropane moiety, which can successfully compete with the usual termination step of a Heck reaction via a <i>syn</i>-b-hydride elimination.<br>

Synthesis of organic halides via palladium(0) catalysis

2014 ◽  
Vol 1 (4) ◽  
pp. 439-446 ◽  
Author(s):  
Chen Chen ◽  
Xiaofeng Tong
Keyword(s):  
Reductive Elimination ◽  
Catalytic Cycle ◽  
Recent Advances ◽  
Organic Halides

This review summarizes the recent advances on the Pd(0)-catalyzed synthesis of organic halides, which involves the carbon halide reductive elimination as a key step in the catalytic cycle.

scholarly journals A new and efficient protocol for the synthesis of the key intermediate of Palbociclib

2019 ◽  
Vol 43 (1-2) ◽  
pp. 14-19
Author(s):  
Shuting Li ◽  
Wanfeng Yang ◽  
Min Ji ◽  
Jin Cai ◽  
Junqing Chen
Keyword(s):  
Nucleophilic Substitution ◽  
Heck Reaction ◽  
Ring Closure ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Synthetic Strategy

A new and efficient synthesis of 6-bromo-8-cyclopentyl-5-methyl-2-(methylsulfinyl)-pyrido[2,3-d]pyrimidin-7(8H)-one, a key intermediate of Palbociclib, starting from thiouracil was described. This protocol involved methylation, nucleophilic substitution, bromination, nucleophilic substitution, Heck reaction, ring closure, oxidation, and bromination to afford a key intermediate of Palbociclib with approximately 35% overall yield. The advantages of this developed synthetic strategy included improved overall yield, inexpensive starting materials, and readily controllable and cleaner reaction conditions.

scholarly journals Deoxydehydration of vicinal diols by homogeneous catalysts: a mechanistic overview

2019 ◽  
Vol 6 (11) ◽  
pp. 191165 ◽  
Author(s):  
Kayla A. DeNike ◽  
Stefan M. Kilyanek
Keyword(s):  
Reaction Mechanism ◽  
Product Distribution ◽  
Catalytic Cycle ◽  
Reaction Conditions ◽  
Homogeneous Catalysts ◽  
Commodity Chemicals ◽  
Reduction Methods ◽  
Vicinal Diols ◽  
Catalyst Systems

Deoxydehydration (DODH) is an important reaction for the upconversion of biomass-derived polyols to commodity chemicals such as alkenes and dienes. DODH can be performed by a variety of early metal-oxo catalysts incorporating Re, Mo and V. The varying reduction methods used in the DODH catalytic cycle impact the product distribution, reaction mechanism and the overall yield of the reaction. This review surveys the reduction methods commonly used in homogeneous DODH catalyst systems and their impacts on yield and reaction conditions.

A Novel Single-Site Catalyst for Olefin Polymerization

2010 ◽  
Vol 657 ◽  
pp. 83-87
Author(s):  
Sriram Venkataramani ◽  
Tharanikkarasu Kannan
Keyword(s):  
Ethylene Polymerization ◽  
Titanium Tetrachloride ◽  
Olefin Polymerization ◽  
Single Site ◽  
Turnover Frequency ◽  
Reaction Conditions ◽  
Co Catalyst ◽  
Infra Red ◽  
Turn Over Frequency ◽  
Turn Over

A novel single-site catalyst was prepared from N-pheneyldiethanolamine and titanium tetrachloride and characterized using spectroscopic methods such as Nuclear Magnetic Resonance (NMR) spectroscopy and Infra Red (IR) spectroscopy. It was prepared insitu and used to polymerize ethylene along with methylaluminoxane (MAO) as co-catalyst. The turnover frequency for ethylene polymerization was found to be 350 g and 550g polymer/mol catalyst/h for 1 bar and at 2 bar respectively. As the turn over frequency at the studied reaction conditions is good, the present N-pheneyldiethanolamine-based catalyst is a good single-site catalyst for olefin polymerization

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