3187-19-7Relevant academic research and scientific papers
Regioselective ortho-carboxylation of phenols catalyzed by benzoic acid decarboxylases: A biocatalytic equivalent to the Kolbe-Schmitt reaction
Wuensch, Christiane,Gross, Johannes,Steinkellner, Georg,Lyskowski, Andrzej,Gruber, Karl,Glueck, Silvia M.,Faber, Kurt
, p. 9673 - 9679 (2014/03/21)
The enzyme catalyzed carboxylation of electron-rich phenol derivatives employing recombinant benzoic acid decarboxylases at the expense of bicarbonate as CO2 source is reported. In contrast to the classic Kolbe-Schmitt reaction, the biocatalytic equivalent proceeded in a highly regioselective fashion exclusively at the ortho-position of the phenolic directing group in up to 80% conversion. Several enzymes were identified, which displayed a remarkably broad substrate scope encompassing alkyl, alkoxy, halo and amino- functionalities. Based on the crystal structure and molecular docking simulations, a mechanistic proposal for 2,6-dihydroxybenzoic acid decarboxylase is presented.
Enantioselective synthesis of a fluorinated analogue of the orsellinic acid-type twelve-membered lactone lasiodiplodin
Runge,Haufe
, p. 8737 - 8742 (2007/10/03)
The chemoenzymatic synthesis of the racemate and the one enantiomer of the fluorinated analogue 8 of the natural cyclooxygenase inhibitor lasiodiplodin is decribed. A lipase-mediated deracemization of the fluorohydrin 18 provided the chiral, nonracemic building block for the enantioselective synthesis of the title compound. The key step was the formation of the 12-membered lactene by a ring-closing metathesis.
Radical-capturing reaction of 5,7,3′,4′-tetramethylquercetin with the AIBN radical initiator
Ishikawa, Takahiro,Takagi, Michiyo,Kanou, Mamiko,Kawai, Shingo,Ohashi, Hideo
, p. 173 - 177 (2007/10/03)
In order to clarify the mechanism for the radical-capturing reaction which is initiated at the C3-hydroxyl group of flavonols, 5,7,3′,4′-tetramethylquercetin (TMQ) was reacted with the 2,2′-azobis-isobutyronitrile (AIBN) radical initiator in benzene. Six products, one depside and its two hydrolytic products, one nitrite adduct, and two others, were isolated from the reaction mixture, and their structures were determined by instrumental analyses. The quantitative change to the four main products against the reaction time was measured by an HPLC method. The radical-capturing reaction pathway for TMQ with AIBN is proposed from these products and their quantitative changes. The pathway dividing into two clearly reveals that one subpath formed the depside and its hydrolytic products, while the other formed the nitrite adduct. The reactivity of each two sub-path was nearly the same, different from the case of TMQ and the 2,2′-azobis-2,4-dimethylvaleronitrile (AMVN) radical initiator.
Macrocycles by ring-closing-metathesis, XI: Syntheses of (R)-(+)- lasiodiplodin, zeranol and truncated salicylihalamides
Fuerstner, Alois,Seidel, Guenter,Kindler, Nicole
, p. 8215 - 8230 (2007/10/03)
Concise, flexible and high yielding approaches to the orsellinic acid type macrolides lasiodiplodin 1 and zeranol 3 are described which involve only metal-assisted or metal-catalyzed C-C-bond formations. Key steps are the efficient allylation of aryl triflates 14 and 25 either by Stille or by modified Suzuki coupling reactions, and the high yielding ring closure of the macrocyclic rings by RCM using the ruthenium carbene 18 as the catalyst. One of the synthesis intermediates, i.e. cycloalkene 16, can also be regarded as a truncated analogue of the potent anti-tumor agent salicylihalamide A 7. From the in-vitro cytotoxicity data of 16 it is possible to deduce first insights into the structure/activity relationship of salicylihalamide.
Macrocycle formation by ring-closing-metathesis. 2. An efficient synthesis of enantiomerically pure (R)-(+)-lasiodiplodin
Fuerstner, Alois,Kindler, Nicole
, p. 7005 - 7008 (2007/10/03)
A highly efficient and flexible route to the macrolide (R)-(+)-lasiodiplodin 1 and its de-O-methyl congener 2 is outlined, which is based on the formation of the 12-membered ring by ring-closing metathesis (RCM) as the key step.
Chemical Studies on the Constituents of the Thymelaeaceous Plants.III. Structure of a Novel Spiro Biflavonoid, Daphnodorin C, from Daphne odora THUNB.
Baba, Kimye,Takeuchi, Kazuo,Doi, Mitsunobu,Kozawa, Mitsugi
, p. 1853 - 1859 (2007/10/02)
The structure of a novel spiro biflavonoid, daphnodorin C (3), previously isolated from the root and bark of Daphne odora THUNB., was established on the basis of chemical and spectral studies, and confirmed by an X-ray diffraction analysis. Keywords---Dap
A New Method for the Degradation of Anthocyanidins, Flavones, Chalcones, and Coumarins
Mentlein, Rolf,Vowinkel, Erich,Wolf, Bernd
, p. 401 - 406 (2007/10/02)
After transformation into the corresponding chalcone or flavenol acetates anthocyanidins are oxidatively cleaved with ruthenium tetroxide to yield benzoic acid derivatives of the rings A and B.Flavones, chalcones, and coumarins are degradated by the same method.
Dye-sensitized Photo-oxygenation of Chalcones
Chawla, H. Mohindra,Chakrabarty, Kakoli
, p. 1511 - 1513 (2007/10/02)
The dye-sensitized photo-oxygenation of several chalcones has been examined.Some of the chalcones give rise to degradation products while others lead to flavonol formation.A rational explanation for the observations has been proposed.The study may have a significance in the biogenesis of naturally occurring plant polyphenolics.
