Boron tribromide → N-(t-butoxycarbonyl)-(+/-)-1,3,4,10b-tetrahydro-9-hydroxy-7-trifluoromethoxy-pyrazino[2,1-a]isoindol-6(2H)-one

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Reaction Steps

To a stirring solution of N-(t-butoxycarbonyl)-(±)-1,3,4,10b-tetrahydro-9-methoxy-7-trifluoromethoxy-pyrazino[2,1-a]isoindol-6(2H)-one (201 mg, 0.5 mmol) in dry CH2Cl2 (3 mL) at −78° C. under Ar was added IM boron tribromide in CH2Cl2 (1.75 mL). The reaction was stirred for 1 h and then warmed to room temperature for 18 h. The reaction was refluxed for 24 h and then quenched with water. The reaction was stirred for 30 min and then conc. in vacuo to a brown solid. The solid was treated with 6M HCl. After 1 h, the reaction was conc. in vacuo to a brown solid. The solid was partioned between water and EtOAc, basified with sodium bicarbonate, and treated with di-t-butyl dicarbonate (109 mg, 0.5 mmol). The reaction was stirred for 1 h and extracted with EtOAc (3×10 mL). The organic layers were combined, dried over MgSO4, and conc. in vacuo to a brown solid. The solid was purified by trituration with chloroform to yield 103 mg of the desired product as a white solid. MS (ESI) 389 (M+H).

Provenance & Evidence