Rates and Equilibria of the Michael-Type Addition of Benzenethiol to 2-Cyclopenten-1-ones.
The triethylamine-catalyzed addition reactions of benzenethiol to 2-cyclopenten-1-one and its 2- and 3-methyl derivatives have been found to be appreciably reversible in chloroform solution. Rates and equilibria have been carefully measured at 25 degrees C in order to assess the negative influence on addition exerted by methyl groups substituted on the carbon-carbon double bond. 2-Methyl-2-cyclopenten-1-one has been found to react with benzenethiol under kinetic control to give the cis adduct as the sole detectable product in a highly stereoselective anti addition process. However, on prolonged reaction times the system slowly evolved toward a new state of equilibrium in which the more stable trans adduct, derived from a syn addition mode, was the predominant isomer.
van Axel Castelli
Valeria
V
Dipartimento di Chimica and Centro CNR Meccanismi di Reazione, Università La Sapienza, Box 34, Roma 62, 00185 Roma, Italy, and Dipartimento di Chimica "G. Ciamician", Università di Bologna, via Selmi, 2, 40126 Bologna, Italy.
Bernardi
Fernando
F
Dalla Cort
Antonella
A
Mandolini
Luigi
L
Rossi
Ivan
I
Schiaffino
Luca
L