ENANTIOSELECTIVE CATALYSIS-107 - NEW OPTICALLY-ACTIVE DELTACYCLENES AS BUILDING-BLOCKS FOR THE SYNTHESIS OF EXPANDED PHOSPHANES

The cobalt-catalyzed home Diels-Alder reaction of norbornadiene and te rminal acetylenes yields chiral deltacyclenes. We tried to extend the scope of this reaction to acetylenes containing a heteroatom (i) in th e propargylic position, (ii) in the ortho position of phenylacetylene or (iii) directly bonded to the triple bond. The synthesis of nine new substituted deltacyclenes with cobalt catalysts derived from CoI2 and zinc powder or Co(acac)(3) and Et2AlCl is described. Using Norphos as a cocatalyst, the products are obtained in high enantiomeric excess.