Lithium Hexamethyldisilazide → HCID 86687726, compound

Participants

Reaction Conditions

Reaction Steps

A vial was charged with N-(2,4-dimethoxybenzyl)-1,2,4-thiadiazol-5-amine (70.7 mg, 0.282 mmol) and THF (938 μl). The resulting solution was cooled to −78° C. for 10 min. Then lithium bis(trimethylsilyl)amide (1M in THF) (413 μl, 0.413 mmol) was added drop wise. The vial was removed from the cold bath temporarily to ensure complete deprotonation of PMB-aminothiadiazole. When the suspension became homogenous, the reaction was cooled back down to −78° C. Then perfluorophenyl 1-(5-chloro-2-methoxyphenyl)-4-oxo-3,4-dihydrophthalazine-6-sulfonate (100 mg, 0.188 mmol) in 0.5 mL of THF was added drop wise. LCMS after 15 min showed complete conversion of SM to product. The reaction was warmed to rt, quenched with 1 mL of MeOH and concentrated. The crude material was absorbed onto a plug of silica gel and purified by chromatography through a Redi-Sep pre-packed silica gel column (12 g), eluting with a gradient of 0% to 70% EtOAc in heptane, to provide 1-(5-chloro-2-methoxyphenyl)-N-(2,4-dimethoxybenzyl)-4-oxo-N-(1,2,4-thiadiazol-5-yl)-3,4-dihydrophthalazine-6-sulfonamide (38 mg, 33.7% yield) as white solid. m/z (ESI) 600.0 (M+H)+, 622.0 (M+Na)+. 1-(5-Chloro-2-methoxyphenyl)-N-(2,4-dimethoxybenzyl)-4-oxo-N-(1,2,4-thiadiazol-5-yl)-3,4-dihydrophthalazine-6-sulfonamide (38 mg, 0.063 mmol) was dissolved in DCM (633 μl, 0.063 mmol) and then TFA (24.4 μl, 0.317 mmol) was added. After 30 min at rt, LCMS showed a complete conversion of SM to product. Purification was done with 0.1% NH4OH in ACN and water as mobile phase to afford 1-(5-chloro-2-methoxyphenyl)-4-oxo-N-(1,2,4-thiadiazol-5-yl)-3,4-dihydrophthalazine-6-sulfonamide (17 mg, 59.7% yield) and NH4OH as a triplet at ˜7.07 ppm. To remove NH4OH, the product was dissolved in MeOH (1 mL) and loaded onto a 2 g SCX column. The product was flushed out with MeOH. Concentration afforded 1-(5-chloro-2-methoxyphenyl)-4-oxo-N-(1,2,4-thiadiazol-5-yl)-3,4-dihydrophthalazine-6-sulfonamide as white solid. m/z (ESI) 450.0 (M+H)+.

Provenance & Evidence