Methyl dimethoxyacetate (1.094 g, 8.15 mmol) and LiOH (420 mg, 10 mmol) were dissolved in 5 ml dioxane and 5 ml water at 0° C. and the reaction mixture stirred 30 minutes at 0° C. and 0.75 hours at r.t. It was then diluted with tBuOMe and washed with NaOH 1M/ice. The aqueous layer was acidified to pH 2 and extracted three times with AcOEt, the combined organic phases dried over Na2SO4 and evaporated to give the dimethoxy-acetic acid as a yellow oil (600 mg). Dimethoxy-acetic acid (8.86 g, 73.8 mmol), obtained from an analogous preparation, was dissolved in 100 ml acetonitrile at 0° C., benzylalcohol (7.3 ml, 70 mmol), EDCI (15 g, 80 mmol) and DMAP (855 mg, 7 mmol) were added and the reaction mixture kept at r.t. during 18 hours. It was then diluted with AcOEt, washed with water, HCl 1M, brine, Na2CO3 (10%) and brine again and the combined organic phases were dried over Na2SO4 and evaporated to give dimethoxy-acetic acid benzyl ester (10.4 g). To crude dimethoxy-acetic acid benzyl ester (4.86 g), were added acetylchloride (2 ml) and iodine (100 mg) as catalyst and the mixture was heated during 4 hours at 65° C., evaporated after addition of 100 ml of ether, diluted with 10 ml CH2Cl2 and added to a solution of triphenylphosphine (25 mmol, 6.63 g) in 50 ml CH2Cl2 and stirred 24 hours at r.t. A chromatography (silicagel; 0.6 kg; elution AcOEt and 1/1 AcOEt/ethanol) provided (benzyloxycarbonyl-methoxy-methyl)-triphenyl-phosphonium chloride as a white foam (6.87 g, 62%).
