Interaction of oxygen functionalized alkenes with a methylaluminoxane–zirconocene catalyst studied by NMR

Reactions of hydroxyl, ether and carbonyl functionalized alkenes with methylaluminoxane prepared in toluene- d 8 (MAO) and zirconocenedichloride (Cp 2 ZrCl 2 ) were investigated by 1 H- and 13 C-NMR spectroscopy at 27°C. The 11 alkenes studied bear a terminal CC bond separated by 7–9 (–CH 2 –) units from the heteroatom moiety. Intramolecular connectivities in mono (alkene), bi (alkene and MAO) and tri (alkene, MAO and Cp 2 ZrCl 2 ) component mixtures were determined by 2D HSQC, HMBC, ROESY and NOESY NMR techniques. The five studied alkenols formed aluminium alkoxides with MAO even in the case of a substantial steric hindrance around the OH group. Zirconocene enhanced the formation of aluminium alkoxides. Decomposition to free alkenol was observed only for the straight chain alkenol (10-undecen-1-ol). The OTMS derivatives formed dimers of the type CH 2 CR 1 R 2 along with methyl derivatives, CH 2 C(Me)(R) and (Me)CHCH(R), in the presence of MAO and Cp 2 ZrCl 2 . 10-Undecenyl methyl ether and methyl decenoate remained mainly as a free comonomer in the presence of MAO or MAO/Cp 2 ZrCl 2 , though a transient coordination of the former to MAO was deduced. Unsaturated species Me 2 CCH–Al–X and CH 2 CH(CH 2 ) 5 CH 2 CHC( t -Bu)O–Al–X (X=MAO oligomer) were formed in the reaction of t -butyl undecenoate or 2,2-dimethyl-11-dodecen-3-one with MAO or MAO/Cp 2 ZrCl 2 . Interaction of the CH 2 CH part of the functionalized alkenes with zirconocene was not observed. A possible coordination of the CC bond to MAO was observed only for the sec alkenols.