Siloxyallenes revisited. A useful functional intermediate for the synthesis of (Z)-β-branched Morita–Baylis–Hillman type adducts and (Z)-chalcones
作者:Kazuhiro Yoshizawa、Takayuki Shioiri
DOI:10.1016/j.tet.2007.02.025
日期:2007.7
Siloxyallenes proved to be a usefulfunctionalintermediate in the preparation of (Z)-β-branched Morita–Baylis–Hillman type adducts by the reaction of aldehydes with silylacetylenes or siloxypropynes. Various (Z)-chalcones were stereoselectively synthesized from siloxypropynes via siloxyallenes.
An efficient one-pot, three-component coupling reaction for the synthesis of unusual β-branched Baylis-Hillman adducts has been developed. Organozinc species CF3CO2ZnEt added to α,β-acetylenic ketones in a 1,4-fashion to yield allenolates, which reacted with aldehydes providing highly functionalized trisubstituted olefins in good to excellent yields with stereoselectivity.
An efficient method for the synthesis of multifunctionalized alkenes has been developed. In the presence of 5 mol% Cul as catalyst, organozinc species CF 3 COOZnEt, CF 3 COOZnMe and CF 3 COOZnPh reacted with α,β-acetylenic ketones and aldehydes in one pot providing trisubstituted alkenes in high yields with stereoselectivity. The reaction with β-substituted-α,β-acetylenic ketones gave tetrasubstituted
Synthesis of Morita–Baylis–Hillman-type adducts by unprecedented reaction of 1-phenyl-2-(trimethylsilyl)acetylene with aromatic aldehydes catalyzed by quaternary ammonium fluorides derived from cinchonine
作者:Kazuhiro Yoshizawa、Takayuki Shioiri
DOI:10.1016/j.tetlet.2005.08.057
日期:2005.10
The quaternary ammonium fluoride derived from cinchonine efficiently catalyzed the reaction of 1-phenyl-2-(trimethylsilyl)acetylene with aromatic aldehydes to give the P-branched Morita-Baylis-Hiliman-type adducts. (c) 2005 Elsevier Ltd. All rights reserved.
Atom Economy: Aldol-Type Products by Vanadium-Catalyzed Additions of Propargyl Alcohols and Aldehydes