Abstract
Metathesis of olefinic amines has been studied with two purposes: (i) to try to carry out at a stoichiometric (or slightly catalytic) level metathesis of olefinic amines to obtain telechelic compounds; (ii) to try to find which parameters play a role in the catalytic process.
Two types of catalytic systems were found to be moderately active in the metathesis of olefinic amines: W(CO)
5L
▪ or W(CO)
3(Arene) (Arene = benzene, toluene, mesitylene) associated with a large excess of C
2H
5AlCl
2 and O
2.
M(NO)
2X
2L
2 associated with an excess of C
2H
5AlCl
2 (X = Cl, Br; M = Mo, W).
The substituents on the nitrogen were found to determine the resulting reactivity of the olefinic amine: steric as well as electronic effects play a role on the acid-base equilibrium between the amine and the Lewis acid cocatalyst. The distance between the double bond and the amine group shows a sharp maximum for olefins of the type CH
2CH(CH
2)
3N(R)(R′). The results are tentatively explained on the basis of an intramolecular stabilization of the metallocarbene moiety by the amine group; this would increase the lifetime of the catalyst. Stereochemical studies seem to indicate that there is no modification of stereochemistry between functionalized and non-functionalized olefins. Consequently the intramolecular stabilization of the metallocarbene moiety and the amine group does not occur in the metallo-cyclobutane transition state formation.