- Chiral chlorohydrins from the biocatalyzed reduction of chloroketones: Chiral building blocks for antiretroviral drugs
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E. coli cells that contain overexpressed alcohol dehydrogenases (ADHs) were screened as biocatalysts for the stereoselective reduction of chloroketones 5 a-d, the corresponding halohydrins 6 a-d of which are building blocks in the synthesis of antiretroviral drugs. Among them, ADH from Sphingobium yanoikuyae was found to reduce chloroketone 5 c with a high stereoselectivity (90 % de) and conversion (85 %) to furnish threo halohydrin (R,S)-6 c. ADH from Ralstonia sp. (RasADH) was able to reduce 5 a and 5 b with complementary diastereoselectivity to provide access to both threo and erythro halohydrins through "substrate-based" stereocontrol. The RasADH-catalyzed reductions were optimized to provide (R,S)-6 a with 98 % conversion and 84 % diastereomeric excess (de) and (S,S)-6 b with 95 % conversion and 86 % de. Molecular modeling studies showed that 5 b, which features a carboxybenzyl protecting group, is able to bind to the enzyme catalytic site in an "inverted" mode in comparison to tert-butyloxycarbonyl- and methyloxycarbonyl-protected substrates 5 a and 5 c, which sheds light on the observed switching of the stereopreference. RasADH-catalyzed reductions were optimized to provide (R,S)-6 a with 98 % conversion and 84 % de and (S,S)-6 b with 95 % conversion and 86 % de.
- De Miranda, Amanda S.,Simon, Robert C.,Grischek, Barbara,De Paula, Gabriel C.,Horta, Bruno A. C.,De Miranda, Leandro S. M.,Kroutil, Wolfgang,Kappe, C. Oliver,De Souza, Rodrigo O. M. A.
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p. 984 - 992
(2015/03/18)
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- Process for reducing α-amino ketones
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The present invention has its objects to provide a method for reducing α-aminoketone derivatives under mild conditions with high stereoselectivity. This invention is a method for reducing α-aminoketone which comprises reacting an a-aminoketone derivative of general formula (1) with a compound prepared from an organoaluminum compound of general formula (4), a sulfonic acid derivative of general formula (5), and an alcohol compound of general formula (6) to give an α-aminoalcohol derivative of general formula (7)
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- Process for the reduction of carbonyl compounds
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PCT No. PCT/JP97/00189 Sec. 371 Date Dec. 29, 1997 Sec. 102(e) Date Dec. 29, 1997 PCT Filed Jan. 29, 1997 PCT Pub. No. WO97/28105 PCT Pub. Date Aug. 7, 1997The present invention provides a process for reducing carbonyl compounds to hydroxy compounds, in particular stereoselectively reducing alpha -aminohaloketone derivatives, under mild conditions in an easy and simple manner, which comprises reacting a carbonyl compound of the general formula (1) with an organoaluminum compound of the general formula (4) to provide the corresponding alcohol compound of the general formula (5).
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- Stereoselective reduction of carbonyl compounds
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A process for the stereoselective reduction via a Meerwein-Ponndorf-Verley (MPV) reaction, of a carbonyl compound to the corresponding alcohol. A preferred starting carbonyl compound is a ketone compound wherein the carbonyl carbon is prochiral. The starting carbonyl compound is contacted with an MPV mediator such as aluminum isopropoxide. The reaction is conducted under mild conditions, e.g. temperatures of about 50°C or less, for less than four hours, and is capable of producing an excess (about 90% to about 97% or more) of a desired optically active chiral alcohol. The mild reaction conditions preserve the optical orientation of other asymmetric centers in the carbonyl compound starting material.
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- Synthesis of the HIV-proteinase inhibitor Saquinavir: A challenge for process research
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The task of process research, namely developing efficient, economically and technically as well as ecologically feasible syntheses in time, is demonstrated on the HIV-proteinase inhibitor Saquinavir (1), a complex molecule comprising six stereo-centres. Based on the first 26-step research synthesis furnishing a 10% overall yield, process research established a new, short 11-step synthesis affording a 50% overall yield.
- Goehring, Wolfgang,Gokhale, Surendra,Hilpert, Hans,Roessler, Felix,Schlageter, Markus,Vogt, Peter
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p. 532 - 537
(2007/10/03)
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- Method of producing halogenated and alpha-aminoalchohols
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A process for the manufacture of N-protected α-aminoketones and N-protected α-aminoalcohols of the formula STR1 wherein X is halogen, one of Q1 and Q2 is hydrogen and the other is hydroxy or Q1 and Q2 together are oxo, R1 is an amino protecting group and R2 is hydrogen or the characterizing group of an α-aminocarboxylic acid, starting from the corresponding lower alkyl N-protected α-aminocarboxylates via corresponding lower alkyl N-silyl protected α-aminocarboxylates.
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