Sodium Carbonate → (3R)-3-(triethylsilyloxy)-4-methyl-5-(2-methylthiazol-4-yl)-pent-4-enal

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Reaction Steps

Osmium tetraoxide (1 wt % in THF, 20.3 mL) is added to a mixture of (4R)-4-(triethylsilyloxy)-5-methyl-6-(2-methylthiazol-4-yl)-1,5-hexadiene (13.5 g), H2O (21 mL), and N-methylmorpholine N-oxide (50% in THF, 10 mL, 0.048 mol) in tert-butanol (155 mL) at 0° C. After the resulting mixture is stirred for 12 hours, Na2SO3 (10 g) and water (5 mL) are added. The resulting solution is stirred at 25° C. for 30 minutes and then extracted with ether. The combined extracts are washed with brine, dried (Na2SO4), filtered, and concentrated. Purification by flash chromatography on SiO2 provides a 1:1 diastereomeric mixture of the diol as a colorless, viscous oil. Lead tetraacetate (19.1 g) is added portionwise over 5 minutes to a suspension of the diol (18.0 g) and Na2CO3 (8.67 g) in 500 mL of benzene at 0° C. After stirring for 15 minutes, the mixture is filtered through a SiO2 pad to afford the aldehyde product. The product is directly subjected to the next reaction.

Provenance & Evidence