32271-56-0Relevant academic research and scientific papers
Sequential Two-Step Stereoselective Amination of Allylic Alcohols through the Combination of Laccases and Amine Transaminases
Albarrán-Velo, Jesús,Lavandera, Iván,Gotor-Fernández, Vicente
, p. 200 - 211 (2019/12/03)
A sequential two-step chemoenzymatic methodology for the stereoselective synthesis of (3E)-4-(het)arylbut-3-en-2-amines in a highly selective manner and under mild reaction conditions is described. The approach consists of oxidation of the corresponding racemic alcohol precursors by the use of a catalytic system made up of the laccase from Trametes versicolor and the oxy-radical TEMPO, followed by the asymmetric reductive bio-transamination of the corresponding ketone intermediates. Optimisation of the oxidation reaction, exhaustive amine transaminase screening for the bio-transaminations and the compatibility of the two enzymatic reactions were studied in depth in search of a design of a compatible sequential cascade. This synthetic strategy was successful and the combinations of enzymes displayed a broad substrate scope, with 16 chiral amines being obtained in moderate to good isolated yields (29–75 %) and with excellent enantiomeric excess values (94 to >99 %). Interestingly, both amine enantiomers can be achieved, depending on the selectivity of the amine transaminase employed in the system.
One-pot two-step chemoenzymatic deracemization of allylic alcohols using laccases and alcohol dehydrogenases
Albarrán-Velo, Jesús,Gotor-Fernández, Vicente,Lavandera, Iván
, (2020/07/03)
A series of enantioenriched (hetero)aromatic secondary allylic alcohols has been synthesized through deracemization of the corresponding racemic mixtures combining a non-selective chemoenzymatic oxidation (laccase from Trametes versicolor and oxy-radical TEMPO) and a stereoselective biocatalyzed reduction (lyophilized cells of E. coli overexpressing an alcohol dehydrogenase, ADH). Both steps were performed in aqueous medium under very mild reaction conditions. After optimization, a sequential one-pot two-step protocol was set up, obtaining the corresponding chiral alcohols in moderate to high conversions (48–95%) and enantiomeric excess (65->99% ee). Depending on the ADH stereopreference, both antipodes from these valuable chiral synthons could be prepared, even at preparative scale (119?178 mg), in a straightforward manner.
Highly activity asymmetric hydrogenation of enones catalyzed by iridium complexes with chiral diamines and achiral phosphines
Chen, Hua,Gao, Xiuli,Jiang, Jian,Li, Chun,Li, Li,Lu, Xunhua,Wang, Mengna,Zhang, Lin,Zhang, Ling
, (2020/02/11)
A selective asymmetric hydrogenation of enones has been well established by using an iridium complex composed of cheap phosphine ligands and cinchona alkaloids derivatives as catalyst. A wide range of allylic alcohol products could be obtained in high chemoselectivities (up to 99.6%), enantioselectivities (70.1% ee) and high activities (up to 3.64 × 104(1/h) TOF). This catalytic system opens a new way of selective asymmetric hydrogenation and the method can be of practical value.
Biocatalytic Enantioselective Oxidation of Sec-Allylic Alcohols with Flavin-Dependent Oxidases
Gandomkar, Somayyeh,Jost, Etta,Loidolt, Doris,Swoboda, Alexander,Pickl, Mathias,Elaily, Wael,Daniel, Bastian,Fraaije, Marco W.,Macheroux, Peter,Kroutil, Wolfgang
supporting information, p. 5264 - 5271 (2019/11/13)
The oxidation of allylic alcohols is challenging to perform in a chemo- as well as stereo-selective fashion at the expense of molecular oxygen using conventional chemical protocols. Here, we report the identification of a library of flavin-dependent oxidases including variants of the berberine bridge enzyme (BBE) analogue from Arabidopsis thaliana (AtBBE15) and the 5-(hydroxymethyl)furfural oxidase (HMFO) and its variants (V465T, V465S, V465T/W466H and V367R/W466F) for the enantioselective oxidation of sec-allylic alcohols. While primary and benzylic alcohols as well as certain sugars are well known to be transformed by flavin-dependent oxidases, sec-allylic alcohols have not been studied yet except in a single report. The model substrates investigated were oxidized enantioselectively in a kinetic resolution with an E-value of up to >200. For instance HMFO V465S/T oxidized the (S)-enantiomer of (E)-oct-3-en-2-ol (1 a) and (E)-4-phenylbut-3-en-2-ol with E>200 giving the remaining (R)-alcohol with ee>99% at 50% conversion. The enantioselectivity could be decreased if required by medium engineering by the addition of cosolvents (e. g. dimethyl sulfoxide).
Chemoselective Luche-Type Reduction of α,β-Unsaturated Ketones by Magnesium Catalysis
Jang, Yoon Kyung,Magre, Marc,Rueping, Magnus
, p. 8349 - 8352 (2019/10/16)
The chemoselective reduction of α,β-unsaturated ketones by use of an economic and readily available Mg catalyst has been developed. Excellent yields for a wide range of ketones have been achieved under mild reaction conditions, short times, and low catalyst loadings (0.2-0.5 mol %).
Silver-catalyzed decarboxylative C(sp2)-C(sp3) coupling reactions: Via a radical mechanism
Fang, Zhongxue,Wei, Chenlong,Lin, Jing,Liu, Zhenhua,Wang, Wei,Xu, Chenshu,Wang, Xuemin,Wang, Yu
supporting information, p. 9974 - 9978 (2017/12/26)
A silver catalyzed decarboxylative C(sp2)-C(sp3) coupling of vinylic carboxylic acids with alcohols, alkylbenzenes, cycloalkanes and cyclic ethers was developed by using DTBP as an oxidant. This reaction tolerates a wide range of substrates, and products are obtained in good to excellent yields. The reaction also shows good stereoselectivity, and only trans-isomers are obtained. In addition, a radical pathway would be involved to facilitate this decarboxylative C(sp2)-C(sp3) coupling reaction.
Chemo-, regio-, and stereoselective Heck-Matsuda arylation of allylic alcohols under mild conditions
Chaudhari, Tohasib Yusub,Hossian, Asik,Manna, Manash Kumar,Jana, Ranjan
supporting information, p. 4841 - 4845 (2015/05/05)
Heck arylation with allylic alcohol is extremely challenging due to chemo-, regio-, and stereoselective scrambling. Here we report a mild protocol for the alcohol selective β- and α-arylation of allylic and cinnamyl alcohols respectively with aryldiazonium salts. The steric and electronic parameters of the alkene play a prominent role in the regioselectivity.
Iridium-catalyzed isomerization/bromination of allylic alcohols: Synthesis of α-bromocarbonyl compounds
Gomez, Antonio Bermejo,Erbing, Elis,Batuecas, Maria,Vazquez-Romero, Ana,Martin-Matute, Belen
supporting information, p. 10703 - 10709 (2014/09/17)
α-Brominated ketones and aldehydes, with two adjacent electrophilic carbon atoms, are highly valuable synthetic intermediates in organic synthesis, however, their synthesis from unsymmetrical ketones is very challenging, and current methods suffer from low selectivity. We present a new, reliable, and efficient method for the synthesis of α-bromocarbonyl compounds in excellent yields and with excellent selectivities. Starting from allylic alcohols as the carbonyl precursors, the combination of a 1,3-hydrogen shift catalyzed by iridium(III) with an electrophilic bromination gives α-bromoketones and aldehydes in good to excellent yields. The selectivity of the process is determined by the structure of the starting allylic alcohol; thus, α-bromoketones formally derived from unsymmetrical ketones can be synthesized in a straightforward and selective manner. Synthon shuffle: An efficient and high-yielding synthetic route to prepare α-bromoketones and aldehydes is presented (see scheme, Cp=pentamethylcyclopentadienyl). The method relies on 1,3-hydrogen shift/bromination of allylic alcohols catalyzed by IrIII complexes. The products are obtained in excellent yields and as single constitutional isomers.
Catalytic stereospecific allyl-allyl cross-coupling of internal allyl electrophiles with allylB(pin)
Le, Hai,Batten, Amanda,Morken, James P.
supporting information, p. 2096 - 2099 (2014/05/06)
Application of internal electrophiles in catalytic stereospecific allyl-allyl cross-coupling enable the rapid construction of multisubstituted 1,5-dienes, including those with all carbon quaternary centers. Compounds with minimal steric differentiation ca
Allylic activation across an Ir-Sn heterobimetallic catalyst: Nucleophilic substitution and disproportionation of allylic alcohol
Chatterjee, Paresh Nath,Roy, Sujit
supporting information; experimental part, p. 3776 - 3785 (2012/07/14)
A nucleophilic substitution of allylic alcohols with carbon (arene, heteroarene, allyltrimethylsilane, and 1,3-dicarbonyl compound), sulfur (thiol), oxygen (alcohol), and nitrogen (sulfonamide) nucleophiles has been demonstrated using an in house developed [Ir(COD)(SnCl3)l(μ-Cl)]2 heterobimetallic catalyst in 1,2-dichloroethane to afford the corresponding allylic products in moderate to excellent yields. In 4-hydroxycoumarin, allylation occurs at the 3-position. The diaryl-substituted allylic alcohols undergo disproportionation in presence of the heterobimetallic catalyst to provide the corresponding alkenes and chalcones. An electrophilic mechanism is proposed from Hammett correlation study.
