T3P (15.67 mL of 1.57M solution in THF) was added dropwise over 15 minutes to a stirred solution of 3-(3-(2-(4-(2-isopropylthiazole-4-carbonyl)-1-oxa-4,9-diazaspiro[5.5]undecan-9-yl)ethyl)phenethoxy)propanoic acid trifluoroacetate salt [Example 34a, step c] (14.4 g) and N-(2,2-dimethoxyethyl)butan-1-amine [J. Am. Chem. Soc. 1949, 71(6), 2272] (3.97 g) and triethylamine (21.83 mL) in DMF (180 mL). The mixture was stirred at 20° C. for 3 hours and then partitioned between ethyl acetate and aqueous brine. The organic layer was washed with aqueous brine (×2), dried over sodium sulphate, filtered and the solvent evaporated under reduced pressure to give the subtitled compound. Yield 15.00 g.
