Enantioselective Synthesis Of α,β-diols Esters By A Novel Dinuclear Zinc-Azephenol Complex

Chiral syn and anti-α,β-dihydroxy esters are important chiral synthons and pharmacophores that serve as the core structures of bioactive polyketide natural products and drugs. The effort of synthezing syn-α,β-dihydroxy ester is pioneering by Shapless through the asymmetric dihydroxylation of α,β-unsaturated ester. While other several catalytic methods have been reported, their applications in synthesis have been limited dued to utilizing chiral auxiliaries, or needing mulisteps, moreover, most of the approaches can only deliever either syn or anti-α,β-dihydroxy ester, the single-crystal x-ray analysis of dihyoxy ester has not been reported. Facile synthesis of the prevalent compounds holds a great potential and remains to be developed.In this thesis, we have developed an asymmetric aldol-type reaction of 2-hydroxyacetophenone with ethyl glyoxylate by a novel dinuclear zinc-Aze Phenol complex, this reaction can afford a series of high entioselectively syn-α,β-dihydroxy esters(ee up to 98%) and anti-α,β-dihydroxy esters(ee up to 99%). The resulting products can be versatile intermieates, they can be transformed into TADDOL, and by comparison to the optical rotation value of the derivatived TADDOL, we can confirm the absolute configurations of the syn-aldol products, while the absolute configurations of anti-aldol products are confirmed by the X-ray crystal structure. The reaction can be carried out in a gram scale without obvious sacrifice of the enatioselectivity, so it has the potential of the industrial process.