Enantiodivergence in the reduction of α-methyl and α-halomethyl enones by microorganisms
摘要:
Enones (Z)-3-methyl-(Z)-3-chloromethyl- and (Z)-3-bromomethyl-4-R-3-buten-2-one (R = n-pentyl, phenyl, 2'- and 4'-chlorophenyl, 3'- and 4'-nitrophenyl, 4'-methoxyphenyl) were synthesized and subjected to reduction by the microorganisms Saccharomyces cerevisiae and Geotrichum candidum. Whereas the bioreduction of 3-methy-4-R-3-buten-2-ones afforded the corresponding (S)-4-R-3-methybutan-2-ones, the bioreduction of 3-chloromethyl- and 3-bromomethyl-4-R-3-buten-2-ones afforded the corresponding (R)-4-R-3-methybutan-2-ones. (C) 2013 Elsevier Ltd. All rights reserved.
Amine and Titanium (IV) Chloride, Boron (III) Chloride or Zirconium (IV) Chloride-Promoted Baylis-Hillman Reactions
作者:Min Shi、Jian-Kang Jiang、Shi-Cong Cui
DOI:10.3390/61100852
日期:——
Baylis-Hillman reactions of various aryl aldehydes with methyl vinyl ketone at temperatures below -20oC using Lewis acids such as titanium (IV) chloride, boron (III) chloride or zirconium (IV) chloride in the presence of a catalytic amount of selected amines used as a Lewis bases afford the chlorinated compounds 1 as the major product in very high yields. Acrylonitrile can also undergo the same reaction to give
Titanium(IV) Chloride and Quaternary Ammonium Salt Promoted Baylis−Hillman Reaction
作者:Min Shi、Yan-Shu Feng
DOI:10.1021/jo0009853
日期:2001.1.1
drastically affected by the reaction temperature and Lewis bases. When the reaction was carried out at -78 degrees C using catalytic amounts of quaternary ammoniumsalts (R4N+X-, X = Cl, Br, I) as Lewis bases, in the presence of titanium(IV) chloride, the chlorinated aldol adduct 1 was obtained as the major product. Quaternary ammoniumbromides and iodides (R4N+X-, X = Br, I) have higher catalytic activity
Efficient nucleophilic substitution reactions of highly functionalized allyl halides in ionic liquid media
作者:S.R.S.Saibabu Kotti、Xin Xu、Guigen Li、Allan D. Headley
DOI:10.1016/j.tetlet.2003.12.051
日期:2004.2
Nucleophilicsubstitution reactions of highly functionalized allyl halides with three anions, N3−, AcO−, and PhSO2−, in ionicliquid media were conducted. The ionicliquid, [Bmim][BF4], was found to be superior to classical organic solvents to give higher yields and faster reaction rates. The resulting products belong to multifunctionalized trisubstituted α,β-unsaturated ketones, which are useful building
Amendment in Titanium(IV) Chloride and Chalcogenide-Promoted Baylis–Hillman Reaction of Aldehydes with α,β-Unsaturated Ketones
作者:Min Shi、Jian-Kang Jiang
DOI:10.1016/s0040-4020(00)00384-7
日期:2000.6
The Baylis–Hillman reaction can be drastically affected by the reaction temperature and Lewis base. When the reaction was carried out at <−20°C using methyl sulfide as a Lewis base in the presence of titanium(IV) chloride, the chlorinated compound 1 was obtained as the major product. However, if the reaction was carried out at room temperature (10°C) in the presence of titanium(IV) chloride, the elimination
Titanium(IV) chloride and oxy-compounds promoted Baylis–Hillman reaction
作者:Min Shi、Jian-Kang Jiang、Shi-Cong Cui
DOI:10.1016/s0040-4020(01)00710-4
日期:2001.8
The Baylis–Hillman reaction of aryl aldehydes with α,β-unsaturated ketones in the presence of titanium(IV) chloride can be promoted by oxy-compounds at room temperature, although they are not as effective as amines, chalcogenides, or quaternary ammonium salts. The oxy-compounds can be simple alcohols, ethers, and ketones. For aryl aldehydes having a strong electron-withdrawing group on the phenyl ring