Potassium Hydroxide → HCID 67598476, Verbindung

To a suspension of the triflate salt obtained in Example 23 (2.34 g, 5.38 mmol) in chloroform (500 mL) was added aqueous 5% KOH. The chloroform layer was separated and the aqueous layer was extracted with chloroform (5×350 mL). The ensuing emulsion was separated from the aqueous layer. Anhydrous Na2CO3 was added to the emulsion until it obtained a paste-like consistency. The aqueous layer was repeatedly extracted with chloroform until the aqueous layer was no longer purple. The Na2CO3 paste was ground with a mortar and pestle and exhaustively extracted with chloroform. All chloroform extracts were combined, dried over anhydrous Na2CO3, filtered and concentrated. The resulting solid was resuspended in chloroform (800 mL), solid anhydrous Na2CO3 was added to the suspension (100 g), and the mixture was sonicated and then concentrated. The resulting solid was poured onto a basic alumina column, eluted sequentially with chloroform (1000 mL), EtOAc-chloroform (1:9, 1000 mL), EtOAc-chloroform (1.5:8.5, 1000 mL), EtOAc-chloroform (2.5:7.5, 1000 mL), and EtOAc-chloroform (3.5:6.5, 1000 mL) to remove the impurities. Elution with 4% methanol in chloroform afforded 1.48 g (96.7%) of the title compound as a purple solid.