To 20 g (0.06 mole) of the 3,4-dibenzyloxybenzoic acid in 200 ml of toluene was added 60 g (0.33 mole) of thionyl chloride. The reaction mixture was evaporated to dryness in vacuo to give a solid; m.p. 85°-86°. The solid was dissolved in 100 ml of dry THF and added dropwise into a solution of 17.7 g (0.06 mole) 3-(t-butylamino)-1,2-propanediol in 50 ml of pyridine and 50 ml of toluene. The reaction mixture was stirred for 1 hour at 25° C. and partitioned between ether and 5% K2CO3 solution. The ether layer was evaporated to dryness to give 30 g of solid.
