- Multiple Enantioselection by an Enzyme-Catalyzed Transacylation Reaction
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Multiply enantioselective enzyme-catalyzed transacylation reactions are described.Two instances of triply enantioselective enzyme-catalyzed transacylations are 1) the reaction of rac-1-indanol with rac-1,1'-bi-2-naphthyl-2,2'-dibutyrate to afford (S)-1-indanol, (R)-1-indanylacetate, (S)-1,1'-bi-2-naphthyl-2,2'-diol, and (R)-1,1'-bi-2-naphthyl-2,2'-dibutyrate and 2) the reaction of rac-1-indanol with rac-2,2'-bis(butyroxymethyl)biphenyl to afford (S)-1-indanol, (R)-1-indanylbutyrate, (S)-2,2'-biphenyldimethanol, and (R)-2,2'-bis(butyroxy-methyl)biphenyl.Doubly enantioselective enzyme-catalyzed transacylations are described according to two instances: 1) the reaction of rac-1-indanol with rac-1,1'-bi-2-naphthyl-2-ol-2'-butyrate afforded (S)-1-indanol, (R)-1-indanylacetate, (S)-1,1'-bi-2-naphthyl-2,2'-diol, and (R)-1,1'-bi-2-naphthyl-2-ol-2'-butyrate, and 2) the reaction of rac-1-indanol with 1,3,5-O-methylidne-2,4,6-tri-O-butyrate-myo-inositol to afford (S)-1-indanol, (R)-1-indanylbutyrate, and 1,3,5-O-methylidne-2,6-di-O-butyrate-myo-inositol.Multiply enantioselective enzyme-catalyzed reactions have a merit of the enhancement of enantiomeric excess over singly enantioselective ones. - Key Words Enzyme in organic synthesis; Kinetic resolution; Lipase.
- Lin, Gialih,Chen, Show-Jane,Sun, Hwey-Lin
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p. 459 - 466
(2007/10/03)
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- Novel Reduction of Carboxylic Acids, Esters, Amides and Nitriles Using Samarium Diiodide in the Presence of Water
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Aromatic carboxylic acids, esters, amides, nitriles, chlorides, ketones and nitro compounds were rapidly reduced by the samarium diiodide-H2O system to the corresponding products at room temperature in good yields.
- Kamochi, Yasuko,Kudo, Tadahiro
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p. 1495 - 1498
(2007/10/02)
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- 5-SUBSTITUTED AND 5,7-DISUBSTITUTED 5,7-DIHYDRODIBENZOTHIEPINS AND THE CORRESPONDING S-OXYGENATED COMPOUNDS: ALKYLAMINES, CARBOXYLIC ACIDS, AND CARBOXAMIDES; SYNTHESIS AND PHARMACOLOGICAL SCREENING
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Reaction of 5,7-dihydrodibenzothiepin with n-butyllithium resulted in the partial sulfur extrusion and in the formation of the 9,10-dihydrophenanthrene-9-thiolate anion (B).Its further transformations (by hydrolysis, aminoalkylation and spontaneous dehydrogenation) led to phenanthrene-9-thiol (IX), the corresponding disulfide X, and the S-(2-dimethylaminoethyl) derivatives XI and XIV.Reactions of 5-chloro-5,7-dihydrodibenzothiepin (II) with the corresponding Grignard reagents were only a poor source of the amines III and IV.Reaction of the sulfoxide XVIII with n-butyllithium or with sodium hydride and the following treatment with 2-dimethylaminoethyl chloride gave the amine XIX in a low yield.Only the sulfone X was found more useful for preparing the 5- and 5,7-substituted derivatives.Treatment with n-butyllithium and following carbonation afforded mixtures of the monocarboxylic acid XXI and dicarboxylic acid XXVIII.Via acid chlorides they were transformed to the methylamides XXII and XXIX and to the dimethylamides XXIII and XXX.The amide XXIII was reduced to the 5-(dimethylaminomethyl) compound XXV.Lithiation of the sulfone XX or treatment with sodium hydride and the following action of 2-dimethylaminoethyl chloride and 3-dimethylaminopropyl chloride gave the amines XXVI, XXVII, and XXXI.Only the phenanthrene derivatives XI and XIV, and the amino sulfone XXVII showed clear indications of thymoleptic activity as potential antidepressants.
- Sindelar, Karel,Holubek, Jiri,Ryska, Miroslav,Koruna, Ivan,Protiva, Miroslav
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p. 2848 - 2868
(2007/10/02)
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- Direct ortho-Metalation of Benzyl Alcohols. A Novel Method of Preparing ortho-Substituted Benzyl Alcohols
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Benzyl alcohol and other phenylcarbinols (8a - 11a), including α-tetralol (12a), are doubly deprotonated by excess n-butyllithium/TMEDA in pentane to give lithium ortho-lithioalkoxides (2, 8b - 12b).Alkylations (-> 3a - d, table 1), reactions with heteroelectrophiles (-> 3e - k, table 2) and with carbonyl compounds (-> 6, 13 - 17, tables 3 and 4), as well as subsequent reactions of the primary adducts (-> phthalanes 7, table 3) furnish a large variety of ortho-substituted benzyl alcohol derivatives.The scope and limitations of the dilithioorganyls (sections B and C), their mode of formation (section A), and attempts to doubly metalate 2-phenylethanol are discussed.
- Meyer, Norbert,Seebach, Dieter
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p. 1304 - 1319
(2007/10/02)
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