Yuefa Gong

Efficient Preparation of Optically Active Ketoprofen by MuCor javanicus Lipase Immobilized on an Inorganic Support.

Lipase M from Mucor javanicus, one of nine commercially available hydrolytic enzymes, showed good enantioselectivity (E=50) for racemic ketoprofen trifluoroethyl ester in phosphate buffer (pH 7.0) containing 30% acetone. Lipase M immobilized on Toyonite 200-A showed the best selectivity (E=55) and reactivity. Moreover, the lipase could be recycled at least 5 times.

Synthesis of α-trifluoromethylated indoleacetic acid: a potential peroxidase-stable plant growth regulator

Abstract A novel trifluoromethylated indoleacetic acid analog was synthesized by condensation of indole with methyl trifluoropyruvate, and the subsequent reduction. The presence of a trifluoromethyl group at the α-position protected this indoleacetic acid from the oxidation of horseradish peroxidase.

Convenient preparation of 1-(indol-3-yl)-2,2,2-trifluoroethylamines via Friedel–Crafts reaction of α-trifluoroacetaldehyde hemiaminal

Abstract Electrophilic substitution of indole with trifluoroacetaldehyde hemiaminals 1a–f, prepared from primary amines and trifluoroacetaldehyde ethyl hemiacetal (TFAE), proceeds readily in the presence of Lewis acids. Formation of N-alkyl 1-(indol-3-yl)-2,2,2-trifluoroethylamines (2) is preferred in the presence of BF3, but yield of 2,2,2-trifluoroethyl alcohol (3) markedly increases when ZnI2 is used. A stereochemistry study clearly showed that ethylamines 2e and 2f are produced with high diastereoselective excess when the optically active hemiaminals 1e and 1f are used.

Lipase-catalyzed optical resolution of trifluoro(aryl)ethanols

Abstract Optical resolutions of racemic 2,2,2-trifluoro-1-(aryl)ethanols — (1-naphthyl), (2-naphthyl), (4-methylnaphthyl), (phenyl), (1-pyrenyl) — were achieved by lipase-catalyzed enantioselective acetylations with vinyl acetate as an acetyl donor in octane, and (S)-acetates and (R)-alcohols were obtained. Among the lipases tested, lipase from Pseudomonas aeruginosa (lipase LIP, Toyobo) showed good enantioselectivity for above ethanols. However, no acetylation occurred with sterically hindered alcohols — (9-phenanthryl), (9-anthryl), (2-methylnaphthyl), (2, 4, 6-trimethylphenyl) — by various lipases. The resolutions of the three alcohols were carried out by the enantioselective alcoholysis or hydrolysis of their chloroacetates by lipase LIP.

Highly diastereoselective synthesis of β-trifluoromethyl-N-acetyltryptophan

Abstract Diethyl 2-[2,2,2-trifluoro-1-(indol-3-yl)ethyl]malonates 1, prepared by the reaction of 2,2,2-trifluoro-1-(indol-3-yl)ethanol 2 with sodium salts of diethyl 2-substituted malonates, were readily hydrolyzed in an aqueous NaOH solution to form the corresponding disodium salts. Subsequent acidification of the salt resulted in the decarboxylation forming syn-isomers of the title compound in high yield.

Unexpected regioselective Heck arylation of ethyl (E)-4,4,4-trifluorocrotonate

Abstract Palladium-catalyzed Heck reactions of ethyl (E)-4,4,4-trifluorocrotonate 1 with aryl bromides 2a–f gave an unexpected α-arylated compound 4, ethyl (Z)-2-aryl-4,4,4-trifluorocrotonate, mainly rather than normal β-arylated compound 3, ethyl (Z)-3-aryl-4,4,4-trifluorocrotonate.

Optical resolution of 2-(3-indolyl)propionic acid with Mucor javanicus and α-chymotrypsin

Resolution of 2-(3-indolyl)propionic acid was achieved via biocatalytic hydrolysis of its chloroethyl ester. Of the enzymes tested, Mucor javanicus lipase (R selectivity) and α-chymotrypsin (S selectivity) had high reactivity and enantioselectivity (E value >xa050). Neither enzyme showed enantioselectivity (E value =xa01) for 2-phenylpropionic acid.

Crystal Structure of Diethyl 2‐[2,2,2‐ trifluoro‐1‐(indole‐3‐yl)‐ethyl]‐2‐acetamidomalonate

The title compound (C 19 H 21 F 3 N 2 O 5 ) has been determined from three dimensional X-ray diffraction data. The crystals are monoclinic, a = 7.626(4)A, b = 17.515(4)A, c = 15.066(3)A, β = 101.02(3)°. V = 1975(1)A 3 , Z = 4, D calc = 1.393g.cm -3 , space group P2 1 /c. The structure was solved by direct methods and refined by full-matrix least-squares method (R = 0.039).

Enzymatic resolution of 3-(3-indolyl)butyric acid: a key intermediate for indolmycin synthesis

Both enantiomers of 3-(3-indolyl)butyric acid, a key intermediate of indolmycin, were successfully prepared by lipase-catalysed enantioselective hydrolysis. Of the enzymes examined, Pseudomonas fluorescens lipase (lipase AK) showed the best enantioselectivity and highest reactivity for the hydrolysis of (±)-trifluoroethyl 3-(3-indolyl)butyrate. Under optimal conditions, optical resolution was completed in one enzyme-catalysed step, the S-acid and unreacted R-ester being obtained in high optical purity.