Sodium triacetoxyborohydride (0.339 g) was added to a stirred solution of 2-fluoro-5-(2-hydroxyethyl)benzaldehyde (example 40, step a) (0.135 g), (2-isopropylthiazol-4-yl)(1-oxa-4,9-diazaspiro[5.5]undecan-4-yl)methanone trifluoroacetate (example 22, step b) (0.339 g) and acetic acid (0.046 mL) in NMP (7 mL). After 16 h, more 2-fluoro-5-(2-hydroxyethyl)benzaldehyde (example 40, step a) (0.135 g) was added followed by sodium triacetoxyborohydride (0.339 g). After 2 h, the reaction mixture was diluted with ethyl acetate (60 mL) and washed with saturated sodium bicarbonate solution (30 mL). The aqueous layer was extracted with ethyl acetate. The combined ethyl acetate solution was evaporated in vacuo. Purification was by silica gel chromatography eluting with ethyl acetate:triethylamine, 10:1 to give the subtitled compound as a gum that contained NMP. The NMP was removed by applying the gum to a 10 g SCX cartridge eluting first with methanol and then 20% ‘880’ aqueous ammonia in methanol to collect the subtitled compound. The solution was evaporated to dryness and the resulting gum applied to a silica gel column eluting with ethyl acetate:triethylamine, 10:1 to give the subtitled compound as a gum. Yield 0.31 g.
