Pyridine → HCID 86760958, compound

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Reaction Steps

Intermediate j obtained in step 9(g) was reacted with N-hydroxysuccinimide and phosgene, as depicted in Scheme 4. Thus, pyridine (0.215 ml, 2.7 mmol) was added dropwise to a stirred solution of Intermediate j (0.385 g, 0.9 mmol) and triphosgene (0.265 g, 0.9 mmol, 3 eq) in dry THF (5 ml). After 20 min, the precipitated pyridine hydrochloride salt was filtered out and the THF was removed by evaporation. The obtained oil was dissolved in dry THF (10 ml). N-hydroxysuccinimide (0.5 g, 4.4 mmol, 5 eq) and pyridine (0.215 ml, 2.7 mmol) were then added and the solution stirred for 20 min. The precipitated pyridine hydrochloride salt was filtered out and the THF was removed by vacuum. The obtained oil was further purified by flash chromatography on silica gel column and elution with ethyl acetate:hexane (1:1 and 4:1). The product, Precursor 5, was obtained in a yield of 88% (0.38 g, 0.78 mmol). ESMS: (ca 482) M: 482.2. HPLC (Chromolith column) 6.68 min (10-100% solution B in 10 min, 3 ml/min). TLC (ethyl acetate:hexane, 1:1, v:v) Rf=0.4.

Provenance & Evidence