Racemize secondaiy alcohols

One of the typical applications of chiral DMAP catalysts is the atylative kinetic resolution of racemic secondary alcohols. Two landmark catalj ts, planer chiral DMAP catalyst 7 and chiral bicyclic PPY catalyst 10, were developed independently by Fu and Kawabata, respectively (Schemes 22.1 and 22.2). Catalysts 7 showed excellent properties as chiral nucleophilic catalysts. In the presence of 2 mol% of 7b, a variety of racemic secondaiy alcohols possessing aryl (or vinyl) and allg l groups such as 8 and 9 were kinetically resolved with acetic anhydride to give the acetates and the recovered starting materials in high enantioselectivity (s = 12-52) (Scheme 22.1). ... 

Scheme 22.1 Acylative kinetic resolution of racemic secondaiy alcohols with Fu s planar-chiral DMAP catalysts.

Deracemization. Enzymatic acetylation of secondaiy benzylic alcohols under racemizing conditions using a ruthenium catalyst leads to chiral esters. 

---