689-00-9Relevant articles and documents
Propargylic C[sbnd]H activation using a Cu(II) 2-quinoxalinol salen catalyst and tert-butyl hydroperoxide
Black, Clayton C.,Gorden, Anne E.V.
supporting information, p. 803 - 806 (2018/02/06)
The oxidation of alkynes to α,β-acetylenic carbonyls was achieved using only 1 mol% of a Cu(II) 2-quinoxalinol salen catalyst with tert-butyl hydroperoxide. These reactions proceed under mild conditions (70 °C) with excellent selectivity, producing yields up to 78%, and were used on a variety of alkyne substrates to produce the desired corresponding α,β-acetylenic ketones. In addition, these reactions can be run under aqueous conditions using a sulfonated version of the 2-quinoxalinol salen with good yields, reducing the need for volatile organic solvents.
Enantioselective synthesis of both enantiomers of various propargylic alcohols by use of two oxidoreductases
Schubert, Thomas,Hummel, Werner,Kula, Maria-Regina,Mueller, Michael
, p. 4181 - 4187 (2007/10/03)
The oxidoreductases Lactobacillus brevis alcohol dehydrogenase (LBADH) and Candida parapsilosis carbonyl reductase (CPCR) are suitable catalysts for the reduction of ketones to afford enantiopure sec. alcohols. A broad variety of alkynones (1, 3, and 5) are accepted as substrates and the corresponding propargylic alcohols (2, 4, and 6) are obtained in good yield and excellent enantiomeric excess. By changing the steric demand of the substituents the ee values can be adjusted and even the configurations of the products can be altered.
Asymmetric reduction of ethynyl ketones and ethynylketoesters by secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus
Heiss, Christian,Phillips, Robert S.
, p. 2821 - 2825 (2007/10/03)
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.