ALPHA'-2,2-HEXAPHENYL-4,5-DIMETHANOL-1,3-DIOXOLANE AS CHIRAL LIGAND OF TITANIUM IN THE DIELS-ALDER REACTION - APPLICATION OF THE EXPERIMENTAL-DESIGN METHODOLOGY AND SOME CONSIDERATIONS ABOUT THE MECHANISM

The Diels-Alder reaction between 3-crotonoyl-1,3-oxazolidin-2-one and cyclopentadiene or 2,3-dimethyl-1,3-butadiene catalyzed by a chiral ti tanium compound derived from lpha',-2,2-hexaphenyl-4,5-dimethanol-1,3- dioxolane is studied, by the application of a 2(f-1) Fractional Factor ial Experimental Design. The influence of four experimental factors is analyzed. High enantiomeric excesses are reached in both reactions an d the effectiveness of the mentioned diol and other diols of the same family is compared. On the other hand, the enantiomeric excess of the chiral auxiliary is correlated with the yield, diastereoselectivity an d enantiomeric excess of the adducts, the amplification of the enantio selectivity being observed.