TRANSITION METAL MEDIATED, STEREOSELECTIVE HIGHER-ORDER [6+4] AND DIELS-ALDER [4+2] CYCLOADDITION REACTIONS: SYNTHESIS OF NOVEL 2-SILYL SUBSTITUTED-1,3-DIENYL COMPOUNDS AND THEIR DOMINO REACTIONS

Abstract

We have prepared various substituted cobaloxime dienes and studied extensively their reactivities in Diels-Alder reactions. Based on the studies with cobaloxime chemistry, we concluded that increased exo selectivities were possible with the insertion of the transition metals in the 2-position of the diene moiety. In the first part of this study, we will describe the higher-order [6+4] and Diels-Alder [4+2] reactions of the cobaloxime dienes with various tropones. The reaction pathway [6+4 vs 4+2] largely depends on the substituents on the tropone moiety where as the stero and regioselectivity is determined only by the cobaloxime.