74620-04-5

Upstream product

• 14051-53-7 flavylium ion 
• 644-78-0 2-hydroxychalcone 
• 644-78-0 2-hydroxychalcone 
• 6272-41-9 2-phenylchromenylium perchlorate 
• 99618-45-8 3c-(2-hydroxy-phenyl)-1-phenyl-propenone 

Downstream Products

• 644-78-0 2-hydroxychalcone 
• 6272-41-9 2-phenylchromenylium perchlorate 
• 99618-45-8 3c-(2-hydroxy-phenyl)-1-phenyl-propenone 
• 14051-53-7 flavylium ion 
• 90-02-8 salicylaldehyde 
• 98-86-2 acetophenone 

Relevant academic research and scientific papers

A bio-inspired synthesis of hybrid flavonoids from 2-hydroxychalcone driven by visible light

A bio-inspired synthesis of hybrid flavonoids from 2-hydroxylchalcone is described. Under the irradiation of 24 W CFL, 2-hydroxychalcone reacts with various nucleophiles to deliver structurally diverse hybrid flavonoids in good to excellent yields in the presence of a catalytic Br?nsted acid. Moreover, moderate enantioselectivities could be obtained using a catalytic chiral phosphoric acid via counter anion directed addition. Based on mechanistic studies, the reaction is proposed to proceed via tandem double-bond isomerization/dehydrated cyclization of 2-hydroxychalcone to form a transient flavylium cation, which is in situ captured by nucleophiles to afford hybrid flavonoids.

Photocyclization reactions. Part 8 [1]. Synthesis of 2-quinolone, quinoline and coumarin derivatives using trans-cis isomerization by photoreaction

2-Quinolone 2, quinoline 3, coumarin (2H-1-benzopyran-2-one) 5, and 2H-1-benzopyran hemiacetal 6 were synthesized by photocyclization reaction of trans-o-aminocinnamoyl derivatives trans-1 and trans-o-hydroxycinnamoyl derivatives trans-4. The reaction proceeds through trans-cis isomerization followed by intramolecular cyclization.

Laser flash photolysis studies of the photo-ring-opening reaction of flav-3-en-2-ol

Electronic structure and photodynamics of flav-3-en-2-ol have been studied by steady-state and time-resolved absorption measurements, and by semi-empirical MO calculations. The photo-ring-opening reaction to produce 2- hydroxychalcone has been determined to be a monophotonic process with the quantum yield of 0.29. The precursor to 2-hydroxychalcone has been assigned to the ground-state enol-form by nanosecond laser flash photolysis study at room temperature and steady-state photolysis study at 77 K. The efficiency of the tautomerization from the ground-state enol-form to keto-form of 2- hydroxychalcone has been estimated to be unity. The enol-form is transformed into 2-hydroxychalcone with the rate constant of 3.2x 104 s-1 in neat acetonitrile, and this process is accelerated by protic molecules. The PM3 calculation of flav-3-en-2-ol showed that the dissociative potential surface in the first excited singlet-state is responsible for the ring-opening reaction.

Hydration of the Flavylium Ion. 3. The Effect of 3-Alkyl Substitution

An investigation is reported of the transformations undergone by four flavylium salts-two 3-methyl-substituted cations, the 3-methylflavylium ion, and the 4'-methoxy-3-methylflavylium ion-and two cations where an ethylene unit bridges the 3-position and the 2'-position of the phenyl ring, the 5,6-dihydrobenzoxanthylium ion, and the 3-methoxy-5,6-dihydrobenzoxanthylium ion.Three transformations have been identified and studied-a rapid and reversible hydration of the cations to produce a pseudobase, the rapid reversible ring opening of this pseudobase to a (Z)-chalcone, and the slow irreversible cis-trans isomerization of this species to an (E)-chalcone.Rate and equilibrium constants have been obtained for these processes and compared with values previously obtained for 3-H-substituted flavylium ions, the parent flavylium ion itself, and the 4'-methoxyflavylium ion.There is little effect of the alkyl substitution on the pseudobase: (Z)-chalcone equilibration.The ethylene-bridged systems undergo cis-trans isomerization at a similar rate to the 3-H systems, while the 3-methyl systems undergo this reaction about 30 times more slowly.The most significant effect, however, is seen on the flavylium ion hydration equilibrium, the bridged cations being about 2 orders of magnitude more stable than their 3-H-substituted counterparts with these in turn 2 orders of magnitude more stable than the 3-methyl analogues.To explain this, it is proposed that there is a steric interaction involving the 3-hydrogen or 3-methyl substituent and an ortho hydrogen on the nearby phenyl ring, resulting in a twisting of this ring so that it is not coplanar with the benzopyrylium portion of the cation.

Hydration of the Flavylium Ion

A spectral and kinetic investigation has been carried out of the transformations undergone in aqueous solution by the parent flavylium ion and its 4'-methyl and 4'-methoxy derivatives.Evidence is reported for the existence at some time under some condition of seven species, the flavylium ion (F+), two pseudobases, a 2-hydroxy adduct (B2) and 4-hydroxy adduct (B4), the cis-2-hydroxychalcone and its ionized form (cC and cC-), and the trans-2-hydroxychalcone and its ionized form (tC and tC-).At pH 6.5-8.5, F+ is relatively rapidly hydrated producing a mixture of B4, B2, and cC.The latter two are in equilibrium, their equilibration proceeding far more rapidly than F+ is hydrated.B4 is a kinetic product of the hydration only; over a short period of time it rearranges via F+ to the equilibrium mixture of B2 and cC.In base solution the behavior is similar, but the B2 cC equilibrium is displaced toward the chalcone since it ionizes.Thus, at pH 12, F+ reacts very rapidly with OH- producing a mixture of B4 and cC-, the latter coming from B2 initially formed.This is followed by the rearrangement of B4, the kinetic product, to cC-.In acid solutions, pH 2-6, an acid-base type equilibrium is relatively rapidly established between the cationic F+ and the neutral species B2 and cC.In all of these solutions, with the exception of strong acids, a slow further reaction occurs resulting eventually in complete transformation to tC or, in base, tC-.The upper limit on the relative amount of cis-chalcone or pseudobase present in equilibrium with the trans-chalcone after complete reaction is 0.02percent.For a scheme B4F+B2cC(cC-)-->tC(tC-), rate constants and equilibrium constants for each reaction stage have been obtained by a kinetic and spectral analysis.