Triethylamine → tert-Butyl 4-(2-isopropylthiazole-5-carbonyl)-1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate

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Reaction Steps

A solution of tert-butyl 1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate hydrochloride (WuXi PharmaTech) (0.694 g) in DMF (13 mL) was treated with triethylamine (1.3 mL), followed by 2-isopropylthiazole-5-carboxylic acid (example 55, step b) (0.406 g) and then O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (1.26 g). The resulting mixture was stirred at RT for 16 h. DMF was removed in vacuo. The residue was taken up in EtOAc (40 mL) and washed with saturated sodium bicarbonate solution (2×40 mL), water (40 mL) and brine (40 mL), dried over sodium sulphate, filtered and evaporated in vacuo. The viscous orange oil was purified by silica gel chromatography eluting with 0-7% MeOH in DCM to give the subtitled compound as a viscous orange oil. Yield 0.765 g.

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