2-Methoxypropene → (4R,5R)-2,2-dimethyl-4-hydroxymethyl-5-[4-(methylsulfonyl)phenyl]-1,3-oxazolidine

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Reaction Steps

(2S,3R)-Ethyl-2-amino-3-[4-(methylsulfonyl)phenyl]-3-hydroxy-propanoate (Compound IV) (100 g, 0.3480 moles) in tetrahydrofuran (500 mL) reacts with lithium aluminum hydride (16.0 g, 0.4224 moles) over 4-8 hours at 60-70° C. to quantitatively yield (1R,2R)-2-amino-1-[4-methylsulfonyl)phenyl]-1,3-propandiol (Compound VII: R1 is methylsulfonyl) (85.36 g, 0.3480 moles). Addition of ethyl acetate (75 mL) destroys any excess lithium aluminum hydride. Addition of xylene (600 mL), 2-methoxypropene (37.6 g, 0.5220 moles), and p-toluenesulfonic acid monohydrate (6.6 g, 0.0348 moles) with agitation at 20-30° C. for 10-16 hours produces (4R,5R)-2,2-dimethyl-4-hydroxymethyl-5-[4-(methylsulfonyl)phenyl]-1,3-oxazolidine (Compound VIII: R1 is methylsulfonyl and R2 and R3 are methyl). Addition of triethylamine (81.3 g, 0.8039 moles) and acetyl chloride (30.0 g, 0.3828 moles) at 20-25° C. for 2-4 hours then addition of water (650 mL) precipitates the crude product. Filtration, washing with water (300 mL) then drying yields (4R,5R)-3-acetyl-2,2-dimethyl-4-hydroxymethyl-5-[4-(methylsulfonyl)phenyl]-1,3-oxazolidine (Compound II).

Provenance & Evidence