Diisopropylethylamine → tert-butyl 2-methyl-2-[(Z)-[2-[[(2R,3S)-2-[[5-[[(2-methylpropan-2-yl)oxycarbonylamino]methyl]tetrazol-2-yl]methyl]-4-oxoazetidin-3-yl]amino]-1-[2-[(2-methylpropan-2-yl)oxycarbonylamino]-1,3-thiazol-4-yl]-2-oxoethylidene]amino]oxypropanoate

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Reaction Steps

To a solution of (Z)-2-(((1-(tert-butoxy)-2-methyl-1-oxopropan-2-yl)oxy)imino)-2-(2-((tert-butoxycarbonyl)amino)thiazol-4-yl)acetic acid (938 mg, 2.18 mmol) in DCM:DMF (5:1, 8.5 mL) at 0° C. was added DIPEA (953 μL, 5.46 mmol) followed by HATU (830 mg, 2.18 mmol). To the resulting solution was added a solution of tert-butyl ((2-(((2R,3S)-3-amino-4-oxoazetidin-2-yl)methyl)-2H-tetrazol-5-yl)methyl)carbamate (541 mg, 1.82 mmol) in DCM:DMF (5:1, 8.5 mL). The solution was stirred at rt for 1 h then concentrated in vacuo, dissolved in EtOAc and washed with brine. The aqueous layer was extracted with EtOAc and the combined organic layers were washed with brine (3×), dried over Na2SO4 and concentrated in vacuo. The crude residue was purified via silica gel chromatography (Acetone-DCM, 30-50%), affording the title compound (897 mg, 70%) as a purple solid. LCMS: Rt=1.01 min, m/z=709.3 (M+1) Method 2m_acidic.

Provenance & Evidence