Formic Acid → HCID 56623594, compound

Participants

Reaction Steps

To a solution of triphenylphosphine (1.647 g), formic acid (0.20 ml), and a mixture (1:3) of methyl 2-[(3S,4R)-3-{(1RS)-1-hydroxyethyl}-4-methylthio-2-oxoazetidin-1-yl]-3-methylbut-2-enoate (1.145 g) in tetrahydrofuran (14 ml) was added dropwise diethyl azodicarboxylate (0.83 ml) at 0° C. under a nitrogen atmosphere. After keeping at the same temperature for 15 minutes, the solution was allowed to warm to room temperature and stirred for two hours. The mixture was cooled to 0° C. and additional fornic acid (24 μl) and diethyl azodicarboxylate (0.10 ml) were added. After stirring at room temperature for one hour, the solution was concentrated, taken up into ethyl acetate (60 ml) and washed with a chilled dilute aqueous sodium bicarbonate, water, and brine. The organic layer was dried over magnesium sulfate, evaporated and re-dissolved in benzene (20 ml) to result in precipitation of crystals. These crystals were collected and washed with benzene. The combined filtrate and washings were evaporated and chromatographed on silica gel (60 g) eluting with 10-30% ethyl acetate in hexane to give a mixture (5:1) of methyl 2-[(3S,4R)-3-{(1RS)-1-formyloxyethyl}-4-methylthio-2-oxoazetidin-1-yl]-3-methylbut-2-enoate (889 mg).

Provenance & Evidence