Dibenzyl 2-methylenepentanedioate → Dibenzyl 2-((bis(benzyloxy)phosphoryl)methyl)pentanedioate

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Reaction Steps

Dibenzyl phosphite (9.5 g, 36 mmol) in 350 ml of dichloromethane was cooled to 0° C. To this stirring solution was added trimethyl aluminum (18.2 ml, 2.0M solution in hexane, 36.4 mmol). After 30 minutes 1 (6.0 g, 37 mmol) in 90 ml of dichloromethane was added dropwise over 10 minutes. The clear and colorless solution was then warmed to room temperature and left to stir overnight. The mixture was then quenched by the slow addition of 5% HCl. After stirring an additional 1.5 hours the lower organic layer was removed and the aqueous layer extracted once with 100ml of dichloromethane. The organics were combined, dried (MgSO4), and evaporated to give a clear light golden liquid. The liquid was chromatographed on silica gel (4 cm*30 cm) and eluted with a gradient (4:1-1:1) solvent system (Hexane/EtOAc). The fractions containing the desired product were combined and evaporated to yield 2 (7.1 g, 42%) as a clear and colorless liquid. The liquid was then distilled on a Kughleror apparatus at 0.5 mm Hg and 195°-200° C. The distillate was discarded and the remaining light golden oil was chromatographed on silica gel (1:1, Hex./EtOAc) to give 2.9 g of 2 as a clear and colorless oil. TLC Rf 0.5 (1:1, Hex./EtOAc)

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