H. Brunner et A. Reimer, ENANTIOSELECTIVE CATALYSIS-107 - NEW OPTICALLY-ACTIVE DELTACYCLENES AS BUILDING-BLOCKS FOR THE SYNTHESIS OF EXPANDED PHOSPHANES, Bulletin de la Societe chimique de France, 134(3-4), 1997, pp. 307-314
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.