128994-28-5Relevant academic research and scientific papers
Asymmetric H2O-Nucleophilic Ring Opening of D-A Cyclopropanes: Catalyst Serves as a Source of Water
Kang, Qi-Kai,Wang, Lijia,Liu, Qiong-Jie,Li, Jun-Fang,Tang, Yong
, p. 14594 - 14597 (2015)
The first catalytic enantioselective ring-opening reaction of donor-acceptor cyclopropanes with water is described. By employing Cy-TOX/Cu(II) as catalyst, the reaction performed very well over a broad range of substrates, leading to the ring-opening products in 70-96% yields with up to 95% ee under mild conditions. The current method provides a new approach to direct access to γ-substituted GBH derivatives very efficiently. Importantly, Cu(ClO4)2·6H2O proves to serve as both a Lewis acid and a source of water, which affords a fine system to controllably release water as a nucleophile in the asymmetric catalysis.
Biocatalytic Asymmetric Reduction of γ-Keto Esters to Access Optically Active γ-Aryl-γ-butyrolactones
??d?o-Dobrowolska, Anna,Borowiecki, Pawe?,Heider, Johann,Kroutil, Wolfgang,Reiter, Tamara,Schühle, Karola,Szaleniec, Maciej,Tataruch, Mateusz,Telatycka, Natalia
supporting information, (2020/04/20)
An efficient stereoselective syntheses of a series of functionalized optically active γ-aryl-γ-butyrolactones is achieved by enzymatic asymmetric reduction of the corresponding sterically demanding γ-keto esters employing wild-type and recombinant alcohol dehydrogenases. The best stereoselectivities for the reduction via hydrogen transfer was obtained with two short chain dehydrogenases (SDRs) of complementary stereospecificity from Aromatoleum aromaticum, namely the Prelog-specific NADH-dependent (S)-1-phenylethanol dehydrogenase [(S)-PED] and the anti-Prelog-specific (R)-1-(4-hydroxyphenyl)-ethanol dehydrogenase [(R)-HPED], respectively.Biotransformations catalyzed by both enzymes, followed by TFA-catalyzed cyclization of the resulting γ-hydroxy esters, furnished the respective (S)- and (R)-configured products with exquisite optical purity (up to >99% ee). The synthetic value was demonstrated on preparative scale for the asymmetric bioreduction of the model compound, methyl 4-oxo-4-phenylbutanoate, affording optically pure (S)-γ-phenyl-γ-butyrolactone (>99% ee) in 67–74% isolated yield at 89–95% conversion depending on the applied scale. (Figure presented.).
Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
, p. 16490 - 16494 (2019/11/03)
Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
Catalytic Redox Chain Ring Opening of Lactones with Quinones to Synthesize Quinone-Containing Carboxylic Acids
Xu, Xiao-Long,Li, Zhi
supporting information, p. 5078 - 5081 (2019/09/03)
Catalytic ring opening of five- to eight-membered lactones with quinones is achieved through a redox chain mechanism. With low loading of a simple metal triflate Lewis acid catalyst and a chain initiator, C-H bonds of many quinones were efficiently functionalized with carboxylic acid-containing side chains. This method also features 100% atom economy and wide substrate scope. A novel route to the anti-asthma drug Seratrodast was developed. Mechanism study suggests that the redox chain reaction likely undergoes a carbocation intermediate.
Synthesis of chiral γ-lactones via a RuPHOX-Ru catalyzed asymmetric hydrogenation of aroylacrylic acids
Lu, Yufei,Li, Jing,Zhu, Yue,Shen, Jiefeng,Liu, Delong,Zhang, Wanbin
supporting information, p. 3643 - 3649 (2019/05/29)
An asymmetric hydrogenation of aroylacrylic acids catalyzed by RuPHOX-Ru catalyst has been developed, affording the corresponding chiral γ-lactones in high yields and with up to 93% ee. The methodology has the advantage of utilizing easily accessible substrates and has therefore expand the scope of the resulting chiral γ-lactones. Furthermore, high catalytic efficiency was achieved in that the reduction of both the C[dbnd]C and C[dbnd]O double bonds was achieved in one step. The current work provides an alternative and convenient pathway for the synthesis of a wide range of chiral γ-lactones.
Chemoselectivity Control in the Asymmetric Hydrogenation of γ- and δ-Keto Esters into Hydroxy Esters or Diols
Arai, Noriyoshi,Namba, Takanori,Kawaguchi, Kei,Matsumoto, Yuki,Ohkuma, Takeshi
supporting information, p. 1386 - 1389 (2018/01/01)
The asymmetric hydrogenation of aromatic γ- and δ-keto esters into optically active hydroxy esters or diols under the catalysis of a novel DIPSkewphos/3-AMIQ–RuII complex was studied. Under the optimized conditions (8 atm H2, Ru complex/t-C4H9OK=1:3.5, 25 °C) the γ- and δ-hydroxy esters (including γ-lactones) were obtained quantitatively with 97–99 % ee. When the reaction was conducted under somewhat harsh conditions (20 atm H2, [t-C4H9OK]=50 mm, 40 °C), the 1,4- and 1,5-diols were obtained predominantly with 95–99 % ee. The reactivity of the ester group was notably dependent on the length of the carbon spacer between the two carbonyl moieties of the substrate. The reaction of β- and ?-keto esters selectively afforded the hydroxy esters regardless of the reaction conditions. This catalyst system was applied to the enantioselective and regioselective (for one of the two ester groups) hydrogenation of a γ-?-diketo diester into a trihydroxy ester.
Cyclic ether synthesis from diols using trimethyl phosphate
Asai, Shota,Kato, Maho,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
supporting information, p. 4787 - 4790 (2017/07/06)
Cyclic ethers have been effectively synthesized via the intramolecular cyclization of diols using trimethyl phosphate and NaH. The present cyclization could proceed at room temperature to produce 5-7 membered cyclic ethers in good to excellent yields. Substrates possessing a chiral secondary hydroxy group were transformed into the corresponding chiral cyclic ethers along with the retention of their stereochemistries.
Preparation of enantioenriched γ-substituted lactones via asymmetric transfer hydrogenation of β-azidocyclopropane carboxylates using the ru-TsDPEN complex
Su, Yan,Tu, Yong-Qiang,Gu, Peiming
, p. 4204 - 4207 (2014/10/15)
The asymmetric transfer hydrogenation of racemic β-azidocyclopropane carboxylates has been explored. Ru-TsDPEN B is found to be a good catalyst for the formation of enantioenriched γ-lactones through a four-step sequence of azide reduction/cyclopropane ri
Enantioselective ketone hydroacylation using noyori's transfer hydrogenation catalyst
Murphy, Stephen K.,Dong, Vy M.
, p. 5553 - 5556 (2013/05/22)
An enantioselective ketone hydroacylation enables the direct preparation of lactones from keto alcohols. The alcohol is oxidized in situ to an aldehyde, obviating the need to prepare sensitive keto aldehyde substrates. Noyori's asymmetric transfer hydroge
Cascade enantioselective synthesis of γ-aryl-γ-butyrolactones with a delayed stereoselective step
Karnik, Anil V.,Kamath, Suchitra S.
, p. 2992 - 2996 (2008/09/19)
Enantioselective synthesis of γ-aryl-γ-butyrolactones is achieved using (S)-1-phenylethylamine as a chiral auxiliary. The synthesis involves cascade formation-destruction-formation of the chiral centre with a delayed stereoselective step. The actual stere
