Synthesis of Dibenzyl mono(2,6-Dimethoxybenzoyl)tartrate from Dibenzyl Tartrate and 2,6-Dimethoxybenozyl chloride -- DMAP as Catalyst

K. Furuta, Q. Gao, H. Yamamoto, Org. Syn., 72, 86, (1995)

1. A mixture of dibenzyl tartrate (6.1 g, 18.5 mmol), triethylamine (4 mL, 28.8 mmol), DMAP (50 mg, 0.4 mmol) and dry dichloromethane (100 mL) is stirred and cooled to 0° C under a nitrogen a®osphere  To this mixture is added 2,6-dimethoxybenozyl chloride (3.65 g, 18.2 mmol) over 1 h.  The reaction mixture is allowed to warm to ambient temperature and then heated under reflux for 12-18 h (monitored by TLC).
2. The reaction mixture is allowed to cool to ambient temperature and is poured into water (100 mL).  The aqueous phase is extracted with dichloromethane (2 x 75 mL); the organic phases are combined, dried over sodium sulfate, filtered, and concentrated to a viscous oil.
3. This oil is purified by column chromatography on silica gel (eluent hexane, ether, dichloromethane 3:1:5) to afford dibenzyl mono(2,6-dimethoxybenzoyl)tartrate (7.1-7.5 g, 78%-82%) as a clear oil.