3,3-Disubstituted prop-2-enoic acids were selectively prepared in good yields under mild experimental conditions via palladium-catalysed cross-coupling of 3-substituted 3-iodobut-2-enoic acids with miscellaneous organometallic reagents using dichlorobis(acetonitrile)palladium(II) as catalyst and DMF as solvent.
Stereospecific synthesis of (Z) or (E)-3-methylalk-2-enoic acids
作者:Mohamed Abarbri、Jean-Luc Parrain、Alain Duchêne
DOI:10.1016/0040-4039(95)00285-k
日期:1995.4
The palladiumcatalysed coupling of organozinc or organotin reagents with 3-iodobut-2(or 3)-enoic acid is stereoselective and affords Z(or E)-3-methylalk-2-enoic acids. The method was applied to the synthesis of the E and Z stereoisomers of ocimenones and pseudo-tagetones.
O-tris(trimethylsilyl)ketene acetal 1 with saturated, cyclic and aromatic ketones 2 proceeds smoothly in the presence of titanium chloride to give (E)-α,β-unsaturated carboxylic acids 3 with fairly good stereoselectivity. With α,β-unsaturated ketones 4, α-trimethylsilyl δ-ketoacids 5 (syn + anti) are obtained according to Michael-type 1,4addition. These diastereoisomers are separated and the configurations