1 scheme 1 shown in the figure is a preferred pathway to accomplish this synthesis the details of which are provided in the following examples all moisture sensitive reactions were performed under nitrogen gas in glassware that was flame dried and equipped with a magnetic stir bar tetrahydrofuran thf and 1 2 dimethoxyethane dme were freshly distilled from sodium benzophenone ketyl before use hexanes pyridine triethylamine pentane and dichloromethane were freshly distilled from cah 2 before use toluene was distilled from sodium thin layer chromatography tlc was performed using e merck silica gel 60 f 254 pre coated plates 0 25 mm flash chromatography was performed using baker silica gel 40 u03bc m particle size all products were purified to homogeneity by tlc analysis single spot two solvent systems using a uv lamp or cam or pma or anisaldehyde or basic kmno 4 for detection purposes nmr spectra were recorded on 400 mhz 500 mhz and 600 mhz spectrometers 1 h and 13 c nmr chemical shifts are reported as u03b4 using residual solvent as an internal standard high resolution mass spectral analyses were performed at harvard university mass spectrometry center a mixture of 2s 3r methyl 2 4 methoxybenzamido 3 hydroxybutanoate 3 35 0 g 131 mmol and p tsoh h 2 0 2 5 g 13 1 mmol in toluene 400 ml was heated at reflux for 12 h the reaction mixture was diluted with water 200 ml and extracted with etoac 3 u00d7 200 ml the combined organic.