A mixture of 6-(2-hydroxy-ethyl)-4-phenyl-chroman-2-ol (Example 7, 30 g, 111 mmol, 1 equiv), diisopropylamine (33.7 g, 333 mmol, 3 eq) and palladium hydroxide on carbon [50% wet catalyst (50% by weight is water), 6 g, 0.2 equiv] in toluene (120 mL) was hydrogenated at 621×103 Nm−2 (90 psi) hydrogen pressure at 110° C. The reaction mixture was cooled to room temperature and filtered through arbocel and evaporated under reduced pressure. The resulting oil was dissolved in acetonitrile (200 mL) and concentrated hydrochloric acid (11.6 mL, 1.05 equiv) was added. The mixture was distilled at ambient pressure, removing approximately 100 mL of acetonitrile, and the distilled solvent replaced with fresh acetonitrile. The mixture was allowed to cool and crystallise overnight. The product was filtered and washed with a small portion of acetonitrile and dried overnight in vacuo at 50° C. to give the title compounds as a white solid (26.7 g, 68.1 mmol, 61%).
