Treatment of Baylis–Hillman adducts with triethyl orthoacetate in the presence of heterogeneous catalysts: a method for the stereoselective synthesis of two different types of trisubstituted alkenes
摘要:
Baylis-Hillman adducts on treatment with triethyl orthoacetate in the presence of HC104-SiO2 afford the corresponding allyl ethyl ethers while in the presence of NaHSO4SiO2 undergo the Johnson-Claisen rearrangement to form ethyl alk-4-enoates. Thus two different types of trisubstituted alkenes are produced in a stereoselective manner using two different hetereogeneous catalysts. (c) 2006 Elsevier Ltd. All rights reserved.
Michael Addition of Methyl 2-(Trimethylsilyl)propenoate with Organomagnesiums or Organolithiums Leading to 1:1 and/or 2:1 Adducts and Subsequent Peterson Olefination by Condensation with Carbonyl Compounds
Michael addition of methyl 2-(trimethylsilyl)propenoate with organomagnesiums or organolithiums leads to 1:1 and/or 1:2 adduct anions which can be utilized in the subsequent step of Peterson olefination with carbonyl compounds. The 1:1/1:2 ratio depends upon the nature of donor molecules, the reaction conditions such as reaction temperature, polarity of solvent, and rate of addition of the acceptor