1413433-48-3

Upstream product

• 491-38-3 1-benzopyran-4(4H)-one 
• 1765-93-1 4-fluoroboronic acid 
• 118-93-4 o-hydroxyacetophenone 
• 1840-01-3 3-(4-fluorophenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one 

Relevant academic research and scientific papers

Rhodium/chiral diene-catalyzed asymmetric 1,4-addition of arylboronic acids to chromones: A highly enantioselective pathway for accessing chiral flavanones

Chromone has been noted to be one of the most challenging substrates in the asymmetric 1,4-addi-tion of α,β-unsaturated carbonyl compounds. By employing the rhodium complex associated with a chiral diene ligand, (R,R)-Ph-bod, the 1,4-addition of a variety of aryl-boronic acids was realized to give high yields of the corresponding flavanones with excellent enantioselectivities (≥97% ee, 99% ee for most substrates). Ring-opening side products, which would lead to erosion of product enantioselectivity, were not observed under the stated reaction conditions.

Palladium-catalyzed asymmetric conjugate addition of arylboronic acids to heterocyclic acceptors

Flava Flavanone: Asymmetric conjugate additions to chromones and 4-quinolones are reported utilizing a single catalyst system formed in situ from Pd(OCOCF3)2 and (S)-tBuPyOX. Notably, these reactions are performed in wet solvent under ambient atmosphere, and employ readily available arylboronic acids as the nucleophile, thus providing ready access to these asymmetric heterocycles (see scheme).

Asymmetric ion-pairing catalysis of the reversible cyclization of 2'-hydroxychalcone to flavanone: Asymmetric catalysis of an equilibrating reaction

The asymmetric catalytic cyclization of the simple 2'-hydroxychalcone (1) to flavanone (2), a model for the chalcone isomerase reaction, has been realized as a catalytic asymmetric ion-pairing process with chiral quaternary ammonium salts (e.g., 9-anthracenylmethlycinchoninium chloride; 9-Am-CN-Cl) and NaH as small-molecule co-catalyst. In toluene/CHCl3 solution, the process reaches an intrinsic enantioselectivity of up to S = 14.4 (er = 93.5:6.5). The reversible reaction proceeds in two steps: A fast initial reaction approaches a quasi-equilibrium with KR/S = 4.5, followed by a second, slow racemization phase approaching Krac = 9. A simple mechanistic model featuring a living ion-pairing catalysis with full reversibility is proposed. Deuterium transfer from co-solvent CDCl3 to product 2 and isolation of a Michael conjugate formed from 2 and 1 demonstrate the intermediacy of flavanone enolate ion pairs. A kinetic model shows good agreement with the experimentally observed, peculiar, time-dependent evolution of the species concentrations and the enantiomeric excess of 2. The reaction is a chemical model of the chalcone isomerase enzymatic reaction. Furthermore, it is an ideal model for studying the characteristic behavior of reversible asymmetric catalyses close to their equilibria.