Sodium triacetoxyborohydride → (9-(2-(5-(2-(tert-Butyldimethylsilyloxy)ethyl)thiophen-2-yl)ethyl)-1-oxa-4,9-diazaspiro[5.5]undecan-4-yl)(2-methylthiazol-4-yl)methanone

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Reaction Steps

(2-Methylthiazol-4-yl)(1-oxa-4,9-diazaspiro[5.5]undecan-4-yl)methanone trifluoroacetate (example 4, step h) (0.25 g) was added to a solution of 2-(5-(2-(tert-butyldimethylsilyloxy)ethyl)thiophen-2-yl)acetaldehyde (0.2 g) (example 4, step g) in a mixture of NMP (5 mL) and acetic acid (0.04 mL). The resulting mixture was stirred for 5 min then sodium triacetoxyborohydride (0.22 g) was added. The mixture was stirred for 1 h and poured into pH 7.2 buffer (50 mL). The aqueous phase was extracted with ethyl acetate (3×50 mL). The combined organics were washed with pH 7.2 buffer (50 mL) and brine (50 mL), then dried over sodium sulphate, filtered and evaporated in vacuo. Purification was by silica gel chromatography eluting with 4:1:0.05 isohexane:ethyl acetate:triethylamine to 95:5 ethyl acetate:triethylamine to give the subtitled compound as a yellow oil. Yield 0.23 g.

Provenance & Evidence