6249-80-5Relevant academic research and scientific papers
Highly Regio-, Diastereo-, and Enantioselective Mannich Reaction of Allylic Ketones and Cyclic Ketimines: Access to Chiral Benzosultam
Qiao, Baokun,Huang, Yin-Jun,Nie, Jing,Ma, Jun-An
, p. 4608 - 4611 (2015)
An organocatalytic asymmetric Mannich reaction of allylic ketones with cyclic N-sulfonyl α-iminoester has been developed. By using a saccharide-derived chiral tertiary amino-thiourea catalyst, a range of allylic ketones and N-sulfonyl ketimines reacted sm
Involvement of an oxidation-reduction equilibrium in chromium-mediated enantioselective Nozaki-Hiyama reactions
Schrekker, Henri S.,Micskei, Karoly,Hajdu, Csongor,Patonay, Tamas,De Bolster, Martin W. G.,Wessjohann, Ludger A.
, p. 731 - 736 (2004)
Ligand induced enantioselective versions of the chromium(II)-mediated Nozaki-Hiyama reaction to homoallyl alcohols proved to be very difficult to achieve, especially if any other nucleophile than the parent allylchromium(III) species was applied. Also, the reaction is frequently accompanied by the formation of oxidation side products, predominantly allyl ketones. This can be explained by an Oppenauer-(Meerwein-Ponndorf-Verley) type mechanism (OMPV reaction). The addition of an enantiopure ligand to racemic chromium homoallyl alcoholate intermediates produced enantiomerically enriched homoallyl alcohols with an enantiomeric excess of up to 32%. This observation not only supports that the proposed OMPV oxidation-reduction equilibrium plays a crucial role in Nozaki-Hiyama reactions, but also proves its involvement in enantioselective versions.
Visible Light-Promoted Recyclable Carbon Nitride-Catalyzed Dioxygenation of β,γ-Unsaturated Oximes
Fu, Xiao-Yang,Si, Ya-Feng,Qiao, Li-Peng,Zhao, Yu-Fen,Chen, Xiao-Lan,Yu, Bing
supporting information, p. 574 - 580 (2021/11/13)
A visible-light-induced dioxygenation of β,γ-unsaturated oximes for the synthesis of diverse useful isoxazolines bearing a hydroxyl moiety was developed by employing graphitic carbon nitride (g-C3N4) as a heterogeneous photocatalyst under an air atmosphere. Noted that, the eminent advantages of this metal-free protocol include step economy, easy operation, a recyclable photocatalyst, external reductant-/oxidant-free and mild reaction conditions. Additionally, mechanistic studies indicated hydroxyl radical was generated under the photocatalysis of g-C3N4.
Organocatalytic Asymmetric Synthesis of Cyclic Acetals with Spirooxindole Skeleton
Shikari, Amit,Mandal, Koushik,Chopra, Deepak,Pan, Subhas Chandra
supporting information, p. 58 - 63 (2021/11/09)
An organocatalytic asymmetric synthesis of cyclic acetal with spirooxindole skeleton has been developed via a domino reaction between isatin and γ-hydroxy enones. Bifunctional squaramide catalyst with adamantyl motif was found to be the most effective for the cascade reaction. With 10 mol% of the catalyst, the desired products were obtained in 1.8:1 to 9:1 diastereo- and 86% to >99% enantioselectivities from a range of substituted isatins and γ-hydroxy enones. (Figure presented.).
Copper-catalyzed radical oxyallylation of olefins for the construction of alkene-containing isoxazolines
He, Xiaoxue,Qian, Lijie,Dai, Yuyu,Yan, Xinhuan,Li, Xiaoqing,Xu, Xiangsheng
supporting information, (2021/05/31)
A radical-mediated approach to alkene oxyallylation using allylic oximes is described. The reaction proceeds under copper-catalytic redox-neutral conditions and tolerates various functional groups. This protocol thus enables the synthesis of structurally valuable isoxazolines and the introduction of a versatile olefin motif in a single step.
Ni-Catalyzed 1,2-Diarylation of Alkenyl Ketones: A Comparative Study of Carbonyl-Directed Reaction Systems
Apolinar, Omar,Derosa, Joseph,Engle, Keary M.,Karunananda, Malkanthi K.,Kleinmans, Roman,Li, Zi-Qi,Tran, Van T.,Wisniewski, Steven R.
supporting information, p. 5311 - 5316 (2021/07/26)
A nickel-catalyzed 1,2-diarylation of alkenyl ketones with aryl iodides and arylboronic esters is reported. Ketones with a variety of substituents serve as effective directing groups, offering high levels of regiocontrol. A representative product is diversified into a wide range of useful products that are not readily accessible via existing 1,2-diarylation reactions. Preliminary mechanistic studies shed light on the binding mode of the substrate, and Hammett analysis reveals the effect of electronic factors on initial rates.
Photocatalytic Stoichiometric Oxidant-Free Synthesis of Linear Unsaturated Ketones from 1,2-Disubstituted Cyclopropanols
Laktsevich-Iskryk, Marharyta V.,Krech, Anastasiya V.,Zhabinskii, Vladimir N.,Khripach, Vladimir A.,Hurski, Alaksiej L.
, p. 1077 - 1086 (2020/12/14)
A one-step catalytic oxidant-free synthesis of unsaturated ketones from 1,2-disubstituted cyclopropanols is reported. Previously for this transformation, only two- and three-step protocols have been developed. The reaction proceeds under irradiation with visible light in the presence of catalytic amounts of both an acridinium photocatalyst and a cobaloxime complex. 2-Aryl-substituted cyclopropanols react giving α,β-unsaturated ketones, while dehydrogenative ring opening of 2-alkyl-substituted substrates affords mixtures of α,β- and β,γ-enones. The reaction starts with one-electron oxidation of a cyclopropanol to cyclopropyloxy radical, presumably, by the photoexcited acridinium catalyst. We also found that Co(dmgBF 2) 2(MeCN) 2complex under an air atmosphere and irradiation with blue LEDs or upon heating can serve as a hydroxycyclopropane oxidant.
Development of a Practical, Biocatalytic Synthesis of tert-Butyl (R)-3-Hydroxyl-5-hexenoate: A Key Intermediate to the Statin Side Chain
Chen, Fener,Hu, Chen,Huang, Zedu,Liu, Minjie,Yue, Xiaoping
supporting information, p. 1700 - 1706 (2020/10/26)
The HMG-CoA reductase inhibitors, statins, are one of the most effective and bestselling cholesterol-lowering drugs. The use of statins has greatly extended people's lives and improved the quality of their life. Development of a more efficient, stereoselective, and sustainable synthesis of statins is continuingly of utmost importance. In the present study, through screening of ketoreductases (KREDs) and reaction optimization, we have successfully performed a highly stereoselective reduction of ketoester 1a catalyzed by KRED-06 at a pilot-plant scale without the addition of exogenous NADP+, generating 3.21 kg of enantiomerically pure tert-butyl (R)-3-hydroxyl-5-hexenoate ((R)-2a) (96.2% yield, >99.9% enantiomeric excess (ee)). This newly developed biocatalytic process alleviates the cryogenic conditions (-40 °C) employed in our first-generation synthesis of (R)-2a using NaBH4 and (l)-tartaric acid. Coupled with our previously established synthesis of bromocarbonate 3a via a one-pot diastereoselective carboxylation/bromocyclization of (R)-2a, we have developed an innovative, practical synthesis route to statin side chain, possessing great potential to be implemented into industrial production of statins.
Photochemical oxidation of benzylic primary and secondary alcohols utilizing air as the oxidant
Nikitas, Nikolaos F.,Tzaras, Dimitrios Ioannis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
supporting information, p. 471 - 477 (2020/02/13)
A mild and green photochemical protocol for the oxidation of alcohols to aldehydes and ketones was developed. Utilizing thioxanthenone as the photocatalyst, molecular oxygen from air as the oxidant and cheap household lamps or sunlight as the light source, a variety of primary and secondary alcohols were converted into the corresponding aldehydes or ketones in low to excellent yields. The reaction mechanism was extensively studied.
Highly Enantioselective Construction of Dihydrooxazines via Pd-Catalyzed Asymmetric Carboetherification
Li, Na,Sun, Baozhen,Liu, Shuang,Zhao, Jinbo,Zhang, Qian
supporting information, p. 190 - 193 (2020/01/02)
A straightforward synthesis of highly enantioenriched 5,6-dihydro-4H-1,2-oxazines is realized by Pd-catalyzed asymmetric carboetherification of γ,δ-alkenyl oximes with (hetero)aryl and alkenyl halides in the presence of a commercially available bisphosphine ligand. The enantioenriched products can be facilely converted to functionalized alcohols with high fidelity of chiral transfer.
