13531-82-3Relevant academic research and scientific papers
Asymmetric reduction of ethynyl ketones and ethynylketoesters by secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus
Heiss, Christian,Phillips, Robert S.
, p. 2821 - 2825 (2000)
Secondary alcohol dehydrogenase (SADH) from Thermoanaerobacter ethanolicus, an NADP-dependent, thermostable oxidoreductase, reduces ethynyl ketones and ethynylketoesters enantioselectively to the corresponding propargyl (propargyl = prop-2-ynyl) alcohols. Ethynyl ketones, in general, are reduced with moderate enantioselectivity (with the exception of 4-methylpent-l-yn-3-one, which gives the (S)-alcohol with >98% ee). Although ethynyl ketones bearing a small (up to n-propyl) alkyl substituent are reduced to (S)-alcohols, larger ethynyl ketones give (R)-alcohols. In contrast, ethynylketoesters are converted to (R)-ethynylhydroxyesters of excellent optical purity. Unexpectedly, isopropyl ethynylketoesters give higher chemical yields and higher enantioselectivities of ethynylhydroxyesters than methyl or ethyl ethynylketoesters. The optically pure ethynylhydroxyesters may serve as useful chiral building blocks for asymmetric synthesis.
The influence of exocyclic stereochemistry on the tethered aminohydroxylation reaction
Donohoe, Timothy J.,Lacy, Adam R.,Rathi, Akshat H.,Walter, Daryl S.
supporting information, p. 3214 - 3222 (2013/01/12)
A new strategy that employs an exocyclic stereocenter to effect diastereocontrol in the tethered aminohydroxylation (TA) reaction is applied to the stereoselective synthesis of a range of amino alcohols in good to excellent yields, and with anti selectivities of up to 20:1. The influence of the reaction conditions and substrate parameters on the level of diastereocontrol is described. Furthermore, an "inside alkoxy" model is employed to rationalize the sense and degree of stereoselectivity observed in these systems. TA for now: Tethered aminohydroxylation (TA) cyclic stereocontrol is possible in the catalytic TA reaction of acyclic systems that bear an exocyclic stereodirecting group. The influence of the alkene substitution pattern and the role of the protecting group on the allylic alcohol are both explored. A model is also presented to rationalize the observed trends in stereoselectivity.
Pheromone synthesis. Part 243: Synthesis and biological evaluation of (3R,13R,1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata, and its stereoisomers
Mori, Kenji,Tashiro, Takuya,Zhao, Boguang,Suckling, David M.,El-Sayed, Ashraf M.
experimental part, p. 2642 - 2653 (2010/05/18)
All of the four stereoisomers of (1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the female sex pheromone of Clania variegata, were synthesized by employing olefin cross metathesis as the key reaction and starting from (R)- or (S)-2-methyl-1-butanol, (R)- or (S)-citronellal, and (S)-2-methyl-3-pentanol. Their bioassay revealed the (3R,13R,1′S)-isomer as the bioactive one, whose more efficient synthesis was achieved in two different ways by employing Wittig reaction as the key step.
Synthesis of all the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata
Mori, Kenji,Tashiro, Takuya
scheme or table, p. 3266 - 3269 (2009/09/05)
All the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Clania variegata, were synthesized by starting from (R)- or (S)-2-methylbutan-1-ol, (R)- or (S)-citronellal, and (S)-2-methylpentan-3-ol. Olefin cross metathesis was employed as the key reaction.
N-Vinylpyridinium tetrafluoroborate salts as reagents for the stereoselective and regioselective synthesis of symmetrical (2E,4E)-1,6-dioxo-2,4-dienes
Gao, Ge,Brown, Neil,Minatoya, Machiko,Buszek, Keith R.
scheme or table, p. 6491 - 6494 (2009/04/06)
We had previously demonstrated the utility of N-vinylpyridinium tetrafluoroborate salts as novel electrophilic coupling partners in Pd(0)-catalyzed Suzuki cross-coupling reactions with aryl and vinyl boronic acids. We now report that these crystalline, air-stable, and non-hygroscopic salts are also useful reagents for the synthesis of symmetrical (2E,4E)-1,6-dioxo-2,4-dienes (diene diones), which in turn are valuable starting materials for the synthesis of various five-membered heterocycles. The optimization of reaction conditions and the scope and limitations of the reductive dimerization are discussed.
Mutation of cysteine-295 to alanine in secondary alcohol dehydrogenase from thermoanaerobacter ethanolicus affects the enantioselectivity and substrate specificity of ketone reductions
Heiss, Christian,Laivenieks, Maris,Zeikus,Phillips, Robert S.
, p. 1659 - 1666 (2007/10/03)
The mutation of Cys-295 to alanine in Thermoanaerobacter ethanolicus secondary alcohol dehycrogenase (SADH) was performed to give C295A SADH, on the basis of molecular modeling studies utilizing the X-ray crystal structure coordinates of the highly homologous T. brockii secondary alcohol dehydrogenase (YKF.PDB). This mutant SADH has activity for 2-propanol comparable to wild-type SADH. However, the C295A mutation was found to cause a significant shift of enantioselectivity toward the (S)-configuration in the reduction of some ethynylketones to the corresponding chiral propargyl alcohols. This result confirms our prediction that Cys-295 is part of a small alkyl group binding pocket whose size determines the binding orientation of ketone substrates, and, hence, the stereochemical configuration of the product alcohol. Furthermore, C295A SADH has much higher actifity towards t-butyl and some α-branched ketones than does wild-type SADH. The C295A mutation does not affect the thioester reductase activity of SADH. The broader substrate specificity and altered stereoselectivity for C295A SADH make it a potentially useful tool for asymmetric reductions. Copyright
