Mechanistic Insights into the Organocatalytic Kinetic Resolution of Oxazinones through Alcoholysis

Synthesis of B-ring-fluorinated (−)-epicatechin gallate derivatives

Organic & Biomolecular Chemistry ◽

10.1039/d0ob00686f ◽

2020 ◽

Vol 18 (21) ◽

pp. 4024-4028

Author(s):

David D. S. Thieltges ◽

Kai D. Baumgarten ◽

Carina S. Michaelis ◽

Constantin Czekelius

Keyword(s):

Kinetic Resolution ◽

Convergent Sequence ◽

Epicatechin Gallate

Electronically modified, fluorinated catechins and epicatechins are enantioselectively synthesized in a short, convergent sequence via kinetic resolution.

Download Full-text

Catalytic Asymmetric Cycloisomerization and Parallel Kinetic Resolution

Synfacts ◽

10.1055/s-0036-1589878 ◽

2017 ◽

Vol 13 (02) ◽

pp. 0174-0174

Keyword(s):

Kinetic Resolution ◽

Parallel Kinetic Resolution ◽

Catalytic Asymmetric

Download Full-text

Probing the Parallel Kinetic Resolution of Racemic Oxazolidinones using Quasi-enantiomeric Profens

10.3390/ecsoc-10-01417 ◽

2006 ◽

Author(s):

Jason Eames ◽

Gregory Coumbarides ◽

Marco Dingjan ◽

Tony Flinn ◽

Northern Northen ◽

...

Keyword(s):

Kinetic Resolution ◽

Parallel Kinetic Resolution

Download Full-text

Catalyst- and Silane- Controlled Enantioselective Hydrofunctionalization of Alkenes by Cobalt-Catalyzed Hydrogen Atom Transfer and Radical-Polar Crossover

10.26434/chemrxiv.9981395 ◽

2020 ◽

Author(s):

Kousuke Ebisawa ◽

Kana Izumi ◽

Yuka Ooka ◽

Hiroaki Kato ◽

Sayori Kanazawa ◽

...

Keyword(s):

Hydrogen Atom ◽

Absolute Configuration ◽

Kinetic Resolution ◽

Hydrogen Atom Transfer ◽

Biologically Active ◽

Atom Transfer ◽

High Concentration ◽

Chain Reaction ◽

Radical Chain ◽

Radical Chain Reaction

Catalytic enantioselective synthesis of tetrahydrofurans, which are found in the structures of many biologically active natural products, via a transition-metal catalyzed-hydrogen atom transfer (TM-HAT) and radical-polar crossover (RPC) mechanism is described herein. Hydroalkoxylation of non-conjugated alkenes proceeded efficiently with excellent enantioselectivity (up to 94% ee) using a suitable chiral cobalt catalyst, <i>N</i>-fluoro-2,4,6-collidinium tetrafluoroborate, and diethylsilane. Surprisingly, absolute configuration of the product was highly dependent on the steric hindrance of the silane. Slow addition of the silane, the dioxygen effect in the solvent, thermal dependency, and DFT calculation results supported the unprecedented scenario of two competing selective mechanisms. For the less-hindered diethylsilane, a high concentration of diffused carbon-centered radicals invoked diastereoenrichment of an alkylcobalt(III) intermediate by a radical chain reaction, which eventually determined the absolute configuration of the product. On the other hand, a more hindered silane resulted in less opportunity for radical chain reaction, instead facilitating enantioselective kinetic resolution during the late-stage nucleophilic displacement of the alkylcobalt(IV) intermediate.

Download Full-text