- Immobilized Baliospermum montanum hydroxynitrile lyase catalyzed synthesis of chiral cyanohydrins
-
Hydroxynitrile lyase (HNL) catalyzed enantioselective C–C bond formation is an efficient approach to synthesize chiral cyanohydrins which are important building blocks in the synthesis of a number of fine chemicals, agrochemicals and pharmaceuticals. Immobilization of HNL is known to provide robustness, reusability and in some cases also enhances activity and selectivity. We optimized the preparation of immobilization of Baliospermium montanum HNL (BmHNL) by cross linking enzyme aggregate (CLEA) method and characterized it by SEM. Optimization of biocatalytic parameters was performed to obtain highest % conversion and ee of (S)-mandelonitrile from benzaldehyde using CLEA-BmHNL. The optimized reaction parameters were: 20 min of reaction time, 7 U of CLEA-BmHNL, 1.2 mM substrate, and 300 mM citrate buffer pH 4.2, that synthesized (S)-mandelonitrile in ~99% ee and ~60% conversion. Addition of organic solvent in CLEA-BmHNL biocatalysis did not improve in % ee or conversion of product unlike other CLEA-HNLs. CLEA-BmHNL could be successfully reused for eight consecutive cycles without loss of conversion or product formation and five cycles with a little loss in enantioselectivity. Eleven different chiral cyanohydrins were synthesized under optimal biocatalytic conditions in up to 99% ee and 59% conversion, however the % conversion and ee varied for different products. CLEA-BmHNL has improved the enantioselectivity of (S)-mandelonitrile synthesis compared to the use of purified BmHNL. Nine aldehydes not tested earlier with BmHNL were converted into their corresponding (S)-cyanohydrins for the first time using CLEA-BmHNL. Among the eleven (S)-cyanohydrins syntheses reported here, eight of them have not been synthesized by any CLEA-HNL. Overall, this study showed preparation, characterization of a stable, robust and recyclable biocatalyst i.e. CLEA-BmHNL and its biocatalytic application in the synthesis of different (S)-aromatic cyanohydrins.
- Jangir, Nisha,Padhi, Santosh Kumar
-
-
- Acceptorless and Base-free Dehydrogenation of Cyanohydrin with (η6-Arene)halide(Bidentate Phosphine)ruthenium(II) Complex
-
Ruthenium-catalyzed dehydrogenation of cyanohydrins under acceptorless and base-free conditions was demonstrated for the first time in the synthesis of acyl cyanide. As opposed to the thermodynamically preferred elimination of hydrogen cyanide, the dehydrogenation of cyanohydrins could be kinetically controlled with ruthenium (II) bidentate phosphine complexes. The effects of the arene, phosphine ligands and counter anions were investigated in regard to catalytic activity and selectivity. Selective dehydrogenation can occur via β-hydride elimination with the experimentally observed [(alkoxide)Ru] complex. (Figure presented.).
- Kim, Kicheol,Moeljadi, Adhitya Mangala Putra,Hirao, Hajime,Hong, Soon Hyeok
-
supporting information
p. 3292 - 3298
(2017/09/06)
-
- Synthesis and X-ray analysis of 2-aryl-4-chloropyrrolidine-2-carbonitrile derivatives
-
Abstract A procedure has been developed for the synthesis of ethyl 1-benzoyl-4-chloro-2-phenylpyrrolidine- 2-carboxylate and 4-chloro-5-oxo-1,2-diphenyl-, 1-benzoyl-2-(2-benzyloxy-5-chlorophenyl)-4-chloro-, and 1-benzoyl-2-(4-benzyloxyphenyl)-4-chloropyrr
- Gasparyan,Alexanyan,Harutyunyan,Martirosyan,Tamazyan,Ayvazyan,Panosyan
-
p. 853 - 859
(2015/08/06)
-
- MORPHOLINE DOPAMINE AGONISTS FOR THE TREATMENT OF PAIN
-
The present invention relates to use of a compound of formula (I), (Ia), or (Ib), wherein A, B, Z, R1and R2 have the meanings given in the specification, as a medicament for the treatment of a number of pain conditions, particularly chronic or nociceptive
- -
-
Page/Page column 45-46
(2008/12/07)
-
- A new (R)-hydroxynitrile lyase from Prunus mume: Asymmetric synthesis of cyanohydrins
-
A new hydroxynitrile lyase (HNL) was isolated from the seed of Japanese apricot (Prunus mume). The enzyme has similar properties with HNL isolated from other Prunus species and is FAD containing enzyme. It accepts a large number of unnatural substrates (benzaldehyde and its variant) for the addition of HCN to produce the corresponding cyanohydrins in excellent optical and chemical yields. A new HPLC based enantioselective assay technique was developed for the enzyme, which promotes the addition of KCN to benzaldehyde in a buffered solution (pH=4.5).
- Nanda, Samik,Kato, Yasuo,Asano, Yasuhisa
-
p. 10908 - 10916
(2007/10/03)
-
- MORPHOLINE DERIVATIVES FOR USE AS DOPAMINE AGONISTS IN THE TREATMENT OF I.A. SEXUAL DYSFUNCTION
-
The present invention provides for compounds of formula (I), (la) and (lb) Wherein: A is selected from C-X and N, B is selected from C-Y and N, R1 is selected from H and (C1-C6)alkyl R2 is selected from H and (C
- -
-
-
- Tetrahydro-isoquinoline-based factor Xa inhibitors
-
Derivatives of (2-amidino-1,2,3,4-tetrahydro-isoquinolin-7- yloxy)phenylacetic acid (TIPAC) were developed as inhibitors of factor Xa (fXa). The compounds are prepared using 15 synthetic steps on average. The most potent compounds (14, 17, 22-26) display inhibition constants of K(i) = 21-55 nM but do not inhibit thrombin (K(i) = 5-> 100 μM) and only weakly inhibit trypsin (K(i) = 0.08-5 μM). They bear a second basic moiety, e.g., substituted 1-(iminomethyl)piperidines, which is linked to C-4 of the phenyl group of TIPAC via an oxygen atom. The inhibition constants of these compounds are almost independent of the size of the (iminomethyl)piperidine substituent. Due to the fact that fXa displays two cation binding sites, namely, the S1 and S4 sites, in principle two binding modes are conceivable for the novel dibasic fXa inhibitors. Molecular modeling experiments based on the X-ray structures of uninhibited fXa and the DX-9065a/fXa complex were carried out. The results taken together with the inhibition constants clearly favor one binding mode: the tetrahydro-isoquinoline fills the S1 pocket even better than the naphthalene moiety of DX-9065a, and the (iminomethyl)piperidine residues occupy the S4 site.
- Kucznierz, Ralf,Grams, Frank,Leinert, Herbert,Marzenell, Klaus,Engh, Richard A.,Von der Saal, Wolfgang
-
p. 4983 - 4994
(2007/10/03)
-
- Enzymatic Preparation of Optically Active Cyanohydrin Acetates
-
A series of cyanohydrin acetates (1)-(47) of widely varying structures, potential chiral building blocks for numerous synthetic applications, has been prepared in good chemical and often high optical yields by enzymatic hydrolysis of their racemic acetates in the presence of an ester hydrolase from Pseudomonas sp.
- Almsick, Andreas van,Buddrus, Joachim,Hoenicke-Schmidt, Petra,Laumen, Kurt,Schneider, Manfred P.
-
p. 1391 - 1393
(2007/10/02)
-
- Some derivatives of 2,4 diamino 5 phenylthiazole (amiphenazole)
-
To facilitate metabolic studies on the analeptic 2,4 diamino 5 phenylthiazole (Amiphenazole) attempts were made to synthesise 2,4 diamino 5 (p hydroxyphenyl) thiazole (unsuccessful) and 2,4 dihydroxy 5 (p hydroxyphenyl) thiazole (successful) as possible metabolites. The pharmacology of some synthetic intermediates revealed that 2,4 diamino 5 (p methoxyphenyl) thiazole was a more potent stimulant than Amiphenazole in morphine depressed respiration of rabbits whilst therapeutic indices were comparable. 2,4 Diamino 5 (p benzyloxyphenyl) thiazole depressed locomotor activity in mice. 2,4 Dihydroxy 5 (p hydroxyphenyl) thiazole did not affect morphine induced analgesia in mice.
- Adams,Nicholls,Williams
-
p. 425 - 427
(2007/10/05)
-