The Preparation of Optically Active Trimethylcyclododecatriene by the Resolution of Racemic Oligomers and the Asymmetric Oligomerization

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Abstract
Trimethylcyclododecatriene was prepared by the oligomerization of pentadiene, using the diethylaluminum chloride-titanium tetrabutoxide system as a catalyst. The resulting oligomer was fractionated by vapor-phase chromatography into geometrical (cis and trans) and structural (head-to-tail and head-to-head) isomers with respect to the pentadiene units involved. The structures of these isomers were proposed on the basis of infrared and NMR spectra of the oligomers and their hydrogenated products. The results of the oxidative degradation of the oligomers were compatible with the proposed structures. Further, the existence of stereoisomers was shown by resolution and asymmetric oligomerization. The resolution of d- and l-enantiomers was carried out through the asymmetric hydroboration of the oligomers, while the asymmetric oligomerization was achieved using the titanium menthoxide-diethylaluminum chloride system as a catalyst.