5 11 s 1h and 3 72 s 3h step 2 4 hydroxymandelic acid methyl ester 18 21 g 100 mmol was redissolved in anhydrous dmf 100 ml and potassium carbonate 2 0 eq 27 6 g 200 mmol was added to the reaction mixture while stirring then slowly 3 4 dichlorobenzylbromide 1 0 eq 23 93 g 100 mmol was added to the reaction mixture in 10 minutes and stirring was continued for 24 h after completion of the reaction ice cold water 500 ml was added to the reaction mixture and stirred for 16 hours the precipitate was filtered off and washed with water 2 u00d7 100 ml and hexanes 3 u00d7 200 ml to give the crude product with a quantitative yield 34 2 g lcms m z 342 m 2 1 h nmr 400 mhz cdcl 3 u03b4 7 53 d 1h 7 45 d 1h 7 35 m 1h 7 33 m 1h 7 25 dd 1h 6 95 m 1h 6 93 m 1h 5 14 s 1h 5 01 s 2h and 3 76 s 3h step 1 u00b1 4 3 4 dichloro benzyloxy phenyl hydroxy acetic acid methyl ester 204 g 0 6 mmol was dissolved in diisopropyl ether 1200 ml then vinyl acetate 3 0 eq 166 ml 1 8 mol and lipase enzyme 113 g amano ps from pseudomonas cepacia were added to this solution the reaction mixture was placed on a shaker the reaction mixture was shaken at room temperature for 140 h the reaction mixture was monitored by chiral hplc after 90 hours of reaction time on a daily basis using chiralpak ad h column 90 10 ratio mixture of hexanes isopropanol as an eluent system after completion the reaction mixture was.