Studies of Diastereoselectivity in Conjugate Addition of Organoaluminum Reagents to (R)-[(p-Tolylsulfinyl)methyl]quinols and Derivatives

( R )-4-Hydroxy-4-[( p -tolylsulfinyl)methyl]-2,5-cyclohexadienones 1 − 3, and 6 reacted with organoaluminum derivatives from the pro- R conjugated position in a highly π-facial diastereoselective manner directed by the C-4 OH. A similar facial diastereoselectivity arose from reactions with 3-alkyl-substituted analogues 4 and 5 and 5-alkyl-4-hydroxy-4-[( p -tolylsulfinyl)methyl]-2-cyclohexenones 10a,b . Semiempirical calculations (AM1 model) provide data on transition-state energies for additions in full agreement with the experimental results.