The polar effect on the regiochemistry of nucleophilic substitution of trifluoromethylated π-allylpalladium complex

• Published in: Journal of organometallic chemistry 2003-06, Vol.676 (1), p.43-48
• Main Authors: Okano, Takashi, Matsubara, Hiroyoshi, Kusukawa, Takahiro, Fujita 1, Makoto
• Format: Article
• Language: English
• Subjects: Regiochemistry; Trifluoromethyl group; π-Allylpalladium complexes; σ-Acceptor
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/S0022-328X(03)00262-6

Allylic nucleophilic substitution of trifluoromethyl-group substituted cinnamyl carbonate with diethyl malonate anion in the presence of palladium complex catalyst gave regio- and stereoselectively the S N2′ product. The regiochemistry caused by the polar effect of trifluoromethyl group was opposite to the methylated cinnamyl substrate in a similar steric environment. The sterically more hindered mesityl and tert-butyl substrates than phenyl derivative also gave the products reacted at the more hindered sites. Although o-substituted substrates expecting intramolecular coordination to affect regiochemistry were examined, no alternative regioisomers were detected. π-Allypalladium-assisted nucleophilic substitution of trifluoromethylated cinnamyl carbonates revealed that the regiochemistry of the reaction is more predominantly determined by the polar effect of the electron-withdrawing group than the steric effect of the substituents on the allylic termini.