Pentane → (R)-2-Methyl-propane-2-sulfinic acid [(R)-2-(tert-butyl-dimethyl-silanyloxy)-1-(6-propoxy-pyridin-3-yl)-ethyl]-amide

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Reaction Steps

A 1.7 M solution of tert-butyllithium in pentane (15.2 mL, 25.8 mmol) was added drop wise to a stirring solution of 5-bromo-2-propoxypyridine IM3 (2.54 g, 11.8 mmol) dissolved in dry THF (29.4 mL) at −78° C. under Ar. The solution was subsequently stirred at this temperature for 30 min. A solution of (R)-2-methyl-propane-2-sulfinic acid [2-(tert-butyl-dimethyl-silanyloxy)ethylidene]-amide IM49 (3.26 g, 11.8 mmol) in dry THF (15 mL) was then added drop wise at −78° C. and the solution was stirred at this temperature for 30 min. The cooling bath was removed and the mixture was allowed to reach room temperature overnight. The mixture was quenched with saturated aqueous NH4Cl solution (75 mL) and EtOAc (150 mL). The phases were separated and the organic layer was washed with brine and then dried over MgSO4. Flash chromatography (silica, 10-100% EtOAc in heptanes) gave (R)-2-Methyl-propane-2-sulfinic acid [(R)-2-(tert-butyl-dimethyl-silanyloxy)-1-(6-propoxy-pyridin-3-yl)-ethyl]amide, the fastest eluding isomer, as a clear oil (2.33 g, 48%) sufficiently pure for the next step. Diastereomeric excess >95% based on 1H NMR.

Provenance & Evidence