Compound 5. Compound 4 (110 mg, 0.22 mmol) was dissolved in 1 M borane THF solution (2 mL) and refluxed under a nitrogen atmosphere overnight. The mixture was then allowed to cool to room temperature before 3 M HCl (10 mL) was added and the solution was refluxed for another 3 h. After cooling to room temperature, the solution was neutralised by addition of NH4OH (15 mL). All solvent was removed in vacuo. The solid residue was re-dissolved in ACN/H20 (1:1, 2 mL) and purified by automated column chromatography on a C18 cartridge (gradient 0-100% ACN:H2O with 0.1% TFA). The fractions containing product were neutralised by addition of 1 M NaOH and dried, yielding 5 as a reddish oil (58.0 mg, 0.12 mmol, 55%).