Triphenylphosphine → (R)-4-(5-ethoxycarbonyl-3-phenoxymethyl-pyrazol-1-ylmethyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester

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Reaction Steps

Di-tert-butyl azodicarboxylate (0.56 g, 2.43 mmol) was added portionwise to a mixture of 5-phenoxymethyl-2H-pyrazole-3-carboxylic acid ethyl ester (0.5 g, 2.0 mmol), (R)-1-boc-2,2-dimethyl-4-hydroxymethyl-oxazolidine (0.49 g, 2.1 mmol) and triphenylphosphine (0.64 g, 2.4 mmol) in THF (10 mL) at 0° C. The mixture was stirred at room temperature for 30 minutes. The solvent was evaporated in vacuo and the residue was purified by flash column chromatography (silica; DCM in heptane 50/50 to 100/0). Desired fractions were collected and the solvent evaporated in vacuo to yield (R)-4-(5-ethoxycarbonyl-3-phenoxymethyl-pyrazol-1-ylmethyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester (0.91 g, 98% yield) as a clear oil.

Provenance & Evidence