Asymmetric synthesis of chiral diols by the catalytic enantioselective dialkylation of tere-, iso-, and phthalaldehydes and by a catalytic enantioselective autoinductive reaction

Optically pure aromatic diols were synthesized by the highly enantioselective dialkylation of aromatic dialdehydes with dialkylzincs in the presence of a catalytic amount of chiral aminoalcohol 1 or chiral thiophosphoramide alcohol 2 with Ti(0-i-Pr)₄. The chiral titanium(IV) alkoxide of 4b, a diisopropylated product of isophthalaldehyde, catalyzed the addition of diisopropylzinc to isophthalaldehyde to gave a chiral zinc alkoxide of 4b with the same configuration by an enantioselective autoinductive reaction (up to 44% e.e.).