Methyl (2S,3R)-2,4-dibromo-3-hydroxybutanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: An argon purged solution of the dibromide obtained in step (b) above (20.8 g, 75.4 mM) and anhydrous sodium acetate (NaOAc) (21.0 g) in ethyl acetate (370 ml) and glacial acetic acid (37 ml) was treated with 5% Pd/C (1.30 g) and the black suspension stirred under one atmosphere of H2 while monitoring uptake (22.4 l/mole). After 2.0 hours H2 uptake was complete, the mixture was filtered through Celite, the filtrate washed with saturated NaHCO3 and brine and then dried over anhydrous MgSO4 and evaporated to give the crude bromoester title product as a brown oil. The crude oil was combined with another batch (starting from 36.77 g of the dibromide) and vacuum distilled to give 25.771 g (61.3%) of the pure bromoester title product as a clear oil with b.p.=79°-80° C. (1.0 mm Hg) and with consistent C13NMR spectral data. TLC (1:1) ethyl acetatehexane, Rf=0.44, PMA. the mixture was filtered through Celite the filtrate washed with saturated NaHCO3 and brine dried over anhydrous MgSO4 evaporated