A chiral guanidine-catalyzed 1,6-addition reaction of 5H-oxazol-4-ones to alpha,beta,gamma,delta-diunsaturated ketones is described in this study. The addition reaction proceeded regiospecifically to yield a 1,6-addition product with high enantioselectivity. Obtained adducts of the 1,6-addition could be converted into the corresponding chiral 7-oxo-alpha-hydroxy acid derivatives or chiral a-homoallylic-hydroxy acid derivatives via 2nd generation Grubbs catalyst-mediated olefin metatheses.