Stereoselective Synthesis of Optically Active 2-Hydroxymandelic Acids and Esters via Friedel−Crafts Coordinated Reaction: Crystal Structure of Chiral Dichloro[2-(1-oxido-1-menthoxy- carbonylmethyl)-4-methoxyphenoxido-O,O,O]titanium

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Abstract
Highly diastereoselective hydroxyalkylation of phenols with chiral glyoxylates was performed. Hydrolysis or reduction of the esters 3 afforded 2-hydroxymandelic acids 6 and diols 5 in high yields and enantiomeric pure form. Mechanistic evidence of chelation-controlled reaction comes from the crystal structure determination of titanium phenoxide complex 8.