On the role of the CF3 group in determining the relative stability of E, Z-isomers

✍ Scribed by Carl L Bumgardner; John E Bunch; M.-H Whangbo

• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 163 KB
• Volume: 27
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)84401-9

✦ Synopsis

Although base-catalyzed addition of PhSH to PhCECCF3 under thermodynamic control gives E_Ph(PhS)C=CH(CF3), .?+Ph(PhO)C=CH(CF3) is the thermodynamically favored product from similar reaction of PhOH with PhCXCF3. The preference for the +-configuration of CF3 and PhO on a double bond is rationalized in terms of frontier orbital interactions. While examining the nucleophilic addition of PhSH and PhOH to trifluoromethyl acetylenes, L-CSC-CF3 (L=Ph, PhCO, etc.), we observed a remarkable effect of the CF 3 group on the stereochemistry of addition. As shown in Scheme I, addition of PhSH to PhCXCF containing a catalytic amount of t-BuO-gives 1-Z as the sole kinetic product,