- Exploration of the expeditious potential of Pseudomonas fluorescens lipase in the kinetic resolution of racemic intermediates and its validation through molecular docking
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A profoundly time-efficient chemoenzymatic method for the synthesis of (S)-3-(4-chlorophenoxy)propan-1,2-diol and (S)-1-chloro-3-(2,5-dichlorophenoxy)propan-2-ol, two important pharmaceutical intermediates, was successfully developed using Pseudomonas fluorescens lipase (PFL). Kinetic resolution was successfully achieved using vinyl acetate as acylating agent, toluene/hexane as solvent, and reaction temperature of 30°C giving high enantioselectivity and conversion. Under optimized condition, PFL demonstrated 50.2% conversion, enantiomeric excess of 95.0%, enantioselectivity (E?=?153) in an optimum time of 1?hour and 50.3% conversion, enantiomeric excess of 95.2%, enantioselectivity (E?=?161) in an optimum time of 3?hours, for the two racemic alcohols, respectively. Docking of the R- and S-enantiomers of the intermediates demonstrated stronger H-bond interaction between the hydroxyl group of the R-enantiomer and the key binding residues of the catalytic site of the lipase, while the S-enantiomer demonstrated lesser interaction. Thus, docking study complemented the experimental outcome that PFL preferentially acylated the R form of the intermediates. The present study demonstrates a cost-effective and expeditious biocatalytic process that can be applied in the enantiopure synthesis of pharmaceutical intermediates and drugs.
- Soni, Surbhi,Dwivedee, Bharat P.,Sharma, Vishnu K.,Patel, Gopal,Banerjee, Uttam C.
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supporting information
p. 85 - 94
(2017/12/26)
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- Asymmetric Hydrolytic and Aminolytic Kinetic Resolution of Racemic Epoxides using Recyclable Macrocyclic Chiral Cobalt(III) Salen Complexes
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New chiral macrocyclic cobalt(III) salen complexes were synthesized and used as catalyst for the asymmetric kinetic resolution (AKR) of terminal epoxides and glycidyl ethers with aromatic/aliphatic amines and water as nucleophiles. This is the first occasion where a Co(III) salen complex demonstrated its ability to catalyze AKR as well as hydrolytic kinetic resolution (HKR) reactions. Excellent enantiomeric excesses of the epoxides, the corresponding amino alcohols and diols (upto 99%) with quantitative yields were achieved by using the chiral Co(III) salen complexes in dichloromethane at room temperature. This protocol was further extended for the synthesis of two important drug molecules, i.e., (S)-propranolol and (R)-naftopidil. The catalytic system was also explored for the synthesis of chirally pure diols and chiral cyclic carbonates using carbon dioxide as a greener renewable C1 source. The catalyst was recycled for upto 5 catalytic cycles with retention of enantioselectivity. (Figure presented.).
- Tak, Rajkumar,Kumar, Manish,Menapara, Tusharkumar,Gupta, Naveen,Kureshy, Rukhsana I.,Khan, Noor-ul H.,Suresh
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supporting information
p. 3990 - 4001
(2017/11/22)
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- Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)-salen complexes: A practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: Computational rationale for enantioselectivity
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A series of chiral polymeric Co(iii)-salen complexes based on a number of achiral and chiral linkers were synthesized and their catalytic performances were assessed in the asymmetric hydrolytic kinetic resolution of terminal epoxides. The effects of the linker were judiciously studied and it was found that in the case of the chiral BINOL-based polymeric salen complex 1, there was an enrichment in catalyst reactivity and enantioselectivity of the unreacted epoxide, particularly in the case of short as well as long chain aliphatic epoxides. Good isolated yields of the unreacted epoxide (up to 46% compared to 50% theoretical yield) along with high enantioselectivity (up to 99%) were obtained in most cases using catalyst 1. Further studies showed that catalyst 1 could retain its catalytic activity for six cycles under the present reaction conditions without any significant loss in activity or enantioselectivity. To show the practical applicability of the above synthesized catalyst we have synthesised some potent chiral β-blockers in moderate yield and high enantioselectivity using complex 1. The DFT (M06-L/6-31+G??//ONIOM(B3LYP/6-31G?:STO-3G)) calculations revealed that the chiral BINOL linker influences the enantioselectivity achieved with Co(iii)-salen complexes. Further, the transition state calculations show that the R-BINOL linker with the (S,S)-Co(iii)-salen complex is energetically preferred over the corresponding S-BINOL linker with the (S,S)-Co(iii)-salen complex for the HKR of 1,2-epoxyhexane. The role of non-covalent C-H?π interactions and steric effects has been discussed to control the HKR reaction of 1,2-epoxyhexane.
- Roy, Tamal,Barik, Sunirmal,Kumar, Manish,Kureshy, Rukhsana I.,Ganguly, Bishwajit,Khan, Noor-Ul H.,Abdi, Sayed H. R.,Bajaj, Hari C.
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p. 3899 - 3908
(2015/02/19)
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- Jacobsen-type enantioselective hydrolysis of aryl glycidyl ethers. 31P NMR analysis of the enantiomeric composition of oxiranes
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The enantioselective partial hydrolysis of a number of racemic aryl glycidyl ethers in the presence of chiral Co(salen)-catalyst was studied. The enantiomeric composition of the isolated (R)-aryl glycidyl ethers was analyzed by 31P NMR using optically active substituted 2-chloro-1,3,2- dioxaphospholanes. A synthesis of β-adrenoblocking agents (S)-toliprolol and (S)-moprolol based on the simultaneously obtained (S)-3-aryloxypropane-1,2- diols was proposed.
- Bredikhin,Strunskaya,Novikova,Azancheev,Sharafutdinova,Bredikhina
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p. 213 - 218
(2007/10/03)
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- Analogs of the dopamine D4 receptor ligand FAUC 113 with planar- and central-chirality
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By employing yeast enzymes, natural amino acids and the Jacobsen's catalyst as sources of chirality, we have synthesized pyrazolo[1,5-a]pyridine derivatives with central- and planar-chirality as analogs of the dopamine D4 receptor ligand FAUC 113. In vitro binding experiments displayed enhanced D2 and D3 affinity for both enantiomers of the [2.2]paracyclophane 3. The C-methylpiperazine (R)-4a revealed excellent D4 selectivity.
- Loeber, Stefan,Ortner, Birgit,Bettinetti, Laura,Huebner, Harald,Gmeiner, Peter
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p. 2303 - 2310
(2007/10/03)
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- CsF in organic synthesis. Regioselective nucleophilic reactions of phenols with oxiranes leading to enantiopure β-blockers
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The two modes of the paths in the reaction of oxiranes with phenols are completely controlled by CsF. Glycidyl nosylate undergoes exclusive substitution at the C1 position whereas the ring-opening (C-3 attack) occurs with epichlorohydrin, glycidol, and 1,2-epoxyalkanes. These reactions provide convenient access to enantiopure β-blockers.
- Kitaori, Kazuhiro,Furukawa, Yoshiro,Yoshimoto, Hiroshi,Otera, Junzo
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p. 14381 - 14390
(2007/10/03)
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- Baker's yeast mediated stereoselective biotransformation of 1-acetoxy-3-aryloxypropan-2-ones
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A series of 1-acetoxy-3-aryloxypropan-2-ones 1a-m were synthesized and subjected to biotransformation by baker's yeast yielding optically active monoacetates 5 or ent-5 and/or diols 4 of moderate to excellent enantiomeric purity. The dependence of the reduction/hydrolysis ratio and stereoselectivity on the size and substitution pattern of the aromatic moiety in the substrate is also discussed.
- Egri, Gabriella,Kolbert, Attila,Balint, Jozsef,Fogassy, Elemer,Novak, Lajos,Poppe, Laszlo
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p. 271 - 283
(2007/10/03)
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- Kinetic resolution of acyclic 1,2-diols using a sequential lipase- catalyzed transesterification in organic solvents
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A method for the kinetic resolution of 3-(aryloxy)-1,2-propanediols rac- 1a-n without additional protection-deprotection steps using a lipase- catalyzed sequential transesterification with lipase amano PS has been developed. In the first step of this one-pot procedure the racemic 1,2-diols are acylated regioselectively at the primary hydroxy group without enantioselection. The subsequent acylation at the secondary hydroxy group of the formed primary monoacetate is responsible for high enantioselection. The enantioselectivity of this transformation depends significantly on the substitution pattern of the aryl ring and the organic solvent used. 3- (Aryloxy)-1,2-propanediols with substituents in the para-position show a much higher enantioselectivity than the corresponding derivatives with ortho- substituents. Among other substrates, the pharmaceuticals Mephenesin, Guaifenesin, and Chlorphenesin have been resolved. The replacement of the aryloxy by an alkyl substituent causes a dramatic decrease of enantioselectivity.
- Theil,Weidner,Ballschuh,Kunath,Schick
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p. 388 - 393
(2007/10/02)
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- Asymmetric dihydroxylation of aryl allyl ethers
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Asymmetric dihydroxylation of substituted aryl allyl ethers is described. Para-substituents are shown to favor high enantioselectivity (89-95%ee), while ortho-groups have a deleterious effect (28-63%ee). Four medicinal agents were prepared: guaifenesin (expectorant), mephenesin (muscle relaxant), chlorphenesin (antifungal) and propanolol (β-blocker).
- Wang,Zhang,Sharpless
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p. 2267 - 2270
(2007/10/02)
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