First efficient synthesis of chlorogenic acid

The first efficient synthesis of chlorogenic acid (1) was achieved in four steps (three purifications) from quinic acid (2). The overall yield was 65% . The key intermediate was quinic acid bisacetonide (6), selectively prepar ed by a modified kinetic acetalization protocol. Esterification of 6 with c affeic acid chloride (3) afforded ester 12. Cleavage of all the protecting groups of 12 was accomplished in one step under acidic conditions. The prog ress of the hydrolysis was monitored by MALDI-MS.