76149-13-8

Upstream product

• 2424-98-8 vinyl isobutyrate 
• 98-85-1 1-Phenylethanol 
• 97-72-3 2-Methylpropionic anhydride 
• 1445-91-6 (S)-1-phenylethanol 
• 7775-39-5 isobutyric acid 1-phenyl-ethyl ester 
• 1517-69-7 (R)-1-phenylethanol 
• 4195-16-8 4-nitrophenyl isobutyrate 
• 1468-39-9 Isovaleric anhydride 

Relevant academic research and scientific papers

Acylative Dynamic Kinetic Resolution of Secondary Alcohols: Tandem Catalysis by HyperBTM and B?ckvall's Ruthenium Complex

Non-enzymatic dynamic kinetic resolution (DKR) of secondary alcohols by enantioselective acylation using an isothiourea-derived HyperBTM catalyst and racemization of slowly reacting alcohol by B?ckvall's ruthenium complex is reported. The DKR approach fea

Two Approaches for CAL-B-Catalyzed Enantioselective Deacylation of a Set of α-Phenyl Ethyl Esters: Organic Solvent with Sodium Carbonate and Micro-aqueous Medium

Herein, we report an efficient enantioselective cleavage of the acyl- moiety of a set of α- phenyl ethyl esters with different chain-lengths catalyzed by lipase B from Candida antarctica (CAL-B) by comparing two reactional approaches: anhydrous media with sodium carbonates and micro-aqueous medium. The deacylation is performed in organic solvent, in the presence of Na2CO3 in the first case, and by addition of a drop of phosphate buffer solution pH 7 in the second. The results show the high efficiency of the deacylation in the presence of the sodium carbonate for the enzymatic resolution of all the esters and that in term of reactivity (31% ≤ conv ≤ 50%) and selectivity (E > 200). While, during the hydrolysis in micro-aqueous media, the conversion is strongly affected by the length of the acyl-chain side, the conversion decreases from conv = 50% with the 1-phenylethyl acetate 1a to conv = 19% with 1-phenyethyl dodecanoate 6a, and this, even if the selectivity remains high (E > 89). In both conditions, the lipase CAL-B shows a high enantioselectivities in favor of (R)-1-phenyl ethanol enantiomer (conv > 45%, E > 200) but the reactivity is modulated by the form and the size of the acyl-chain side. Graphic Abstract: [Figure not available: see fulltext.].

Acylative Kinetic Resolution of Alcohols Using a Recyclable Polymer-Supported Isothiourea Catalyst in Batch and Flow

A polystyrene-supported isothiourea catalyst, based on the homogeneous catalyst HyperBTM, has been prepared and used for the acylative kinetic resolution of secondary alcohols. A wide range of alcohols, including benzylic, allylic, and propargylic alcohols, cycloalkanol derivatives, and a 1,2-diol, has been resolved using either propionic or isobutyric anhydride with good to excellent selectivity factors obtained (28 examples, s values up to 600). The catalyst can be recovered and reused by a simple filtration and washing sequence, with no special precautions needed. The recyclability of the catalyst was demonstrated (15 cycles) with no significant loss in either activity or selectivity. The recyclable catalyst was also used for the sequential resolution of 10 different alcohols using different anhydrides with no cross-contamination between cycles. Finally, successful application in a continuous flow process demonstrated the first example of an immobilized Lewis base catalyst used for the kinetic resolution of alcohols in flow.

Kinetic resolution of secondary carbinols by a chiral N,N-4-dimethylaminopyridine derivative containing a 1,1′-binaphthyl unit: Hydrogen bonding affects catalytic activity and enantioselectivity

We developed an acylative kinetic resolution of secondary carbinols using a binaphthyl-based N,N-4-dimethylaminopyridine (DMAP) derivative 1d with tert-Alcohol substituents. The reaction proceeded with a wide range of carbinols with moderate to high selectivity (s) (up to s = 79.5). Kinetic studies revealed that catalyst 1d was more catalytically active than the corresponding bis-methyl ether 1d′ or DMAP. Hydrogen bonding between tert-Alcohols of the catalyst and secondary carbinols was responsible for the enhanced reaction rate and high enantioselectivity.

Catalytic enantioselective acyl transfer: the case for 4-PPY with a C-3 carboxamide peptide auxiliary based on synthesis and modelling studies

A series of 4-pyrrolidinopyridine (4-PPY) C-3 carboxamides containing peptide-based side chains have been synthesised and evaluated in the kinetic resolution of a small library of chiral benzylic secondary alcohols. A key design element was the incorporation of a tryptophan residue in the peptide side chain for promoting π-stacking between peptide side chain and the pyridinium ring of the N-acyl intermediate, in which modelling was used as a structure-based guiding tool. Together, a catalyst containing a LeuTrp-N-Boc side chain (catalyst 8) was identified that achieved s-values up to and in slight excess of 10. A transition-state model based on the modelling is proposed to explain the origin of enantioselectivity. This study establishes the usefulness of modelling as a structure-based guiding tool for enantioselectivity optimization as well as the potential for developing scalable peptide-based DMAP-type catalysts for large-scale resolution work.

Fluxionally chiral DMAP catalysts: Kinetic resolution of axially chiral biaryl compounds

Can organocatalysts that incorporate fluxional groups provide enhanced selectivity in asymmetric transformations? To address this issue, we have designed chiral 4-dimethylaminopyridine (DMAP) catalysts with fluxional chirality. These catalysts were found

Structure-activity relationship of dihydroimidazo-, dihydropyrimido, tetrahydrodiazepino-[2,1-b]-thiazoles, and -benzothiazoles as an acylation catalyst

Cyclic isothioureas 1, 2, 3, and 4 were synthesized through a four-step procedure from the corresponding ortho-bromoanilines 10 via Pd- or Cu-catalyzed cyclization-benzothiazole formation. Nonbenzo analogues 7, 8, and 9 were synthesized by a condensation reaction of cyclic thioureas 15 and α-bromoacetophenones 14. Investigations of the acylation reactions of 1-phenylethanol with acid anhydrides in the presence of these cyclic isothiourea catalysts revealed their structure-activity relationships. Remarkable electronic effects resulting from substituent(s) on a benzo or phenyl moiety and the influence of the size of the annulating ring were observed. Introduction of an electron-donating substituent(s) enhanced the reaction rate. A few substitution effects on chiral catalysts of type 3 and 7 were also studied.

Kinetic resolution of secondary alcohols by chiral dmap derivatives prepared by the Ugi multicomponent reaction

The kinetic resolution of secondary alcohols was examined by new chiral DMAP derivatives, which can readily be prepared by the Ugi multicomponent reaction in a one-pot operation. The initial screening of DMAP derivatives indicated that the catalyst bearing L-valine with an S configuration at the a-position of amide showed the best stereoselectivity factor. After the reaction conditions were optimized with (S,S)-4a in the kinetic resolution of secondary alcohols, various acyclic and cyclic secondary alcohols could be resolved with an s -factor of up to 12.

Design, synthesis, and evaluation of a helicenoidal DMAP lewis base catalyst

The design, synthesis, and study of a helical dialkylaminopyridine Lewis base catalyst is reported. Helical DMAP analogue 4 is based upon a helicenoid structure and displays good to excellent levels of selectivity (S ≤ 116) in the kinetic resolution of chiral secondary alcohols. Catalyst 4 displays excellent reactivity with exceptionally low loadings of 0.05 mol % effecting practical levels of selectivity in kinetic resolutions.(Figure Presented)

Organocatalysis with azahelicenes: The first use of helically chiral pyridine-based catalysts in the asymmetric acyl transfer reaction

The successful utilisation of a helicene-based organocatalyst in acylative kinetic resolution of racemic secondary alcohol was described. Employing rac-1-phenylethanol, optically pure (-)-(M)-2-aza[6]helicene (5-20 mole %), isobutyric anhydride and N-ethyldiisopropylamine in chloroform at 22-40 °C, an asymmetric acyl transfer reaction took place overwhelming the uncatalysed background process. Moderate reactivity as well as selectivity factor (s = 9, 10) were observed. An effective control of the enantiodiscriminating step in acylative kinetic resolution by the helically chiral organocatalyst was proven for the first time.