Ammonium Chloride → tert-butyl (3S,5S,8S)-8-(benzyloxymethyl)-6-hydroxy-3-((1-(3-methoxypropyl)-1H-indazol-6-yl)methyl)-2,9-dimethyldecan-5-ylcarbamate

Participants

Reaction Conditions

Reaction Steps

A 250-mL, three-neck, round-bottom flask equipped with a condenser under N2 was charged with Mg powder (1.36 g, 56.7 mmol). The mixture was warmed briefly with a heat gun and a solution (S)-((2-(bromomethyl)-3-methylbutoxy)methyl)benzene (10.5 g, 37.8 mmol) in anhydrous THF (100 mL) was added dropwise. When the reaction mixture reached reflux temperature the heat gun was stopped. The mixture was stirred for an additional 30 min to afford a solution of (S)-(2-(benzyloxymethyl)-3-methylbutyl)magnesium bromide. A second 250-mL, three-neck round-bottom flask was charged with a solution of tert-butyl (2S,4S)-4-((1-(3-methoxypropyl)-1H-indazol-6-yl)methyl)-5-methyl-1-oxohexan-2-ylcarbamate (2.7 g, 6.3 mmol) in anhydrous THF (50 mL) and cooled to −78° C. under N2 and the solution was stirred for 30 min. The freshly prepared solution of (S)-(2-(benzyloxymethyl)-3-methylbutyl)magnesium bromide prepared above was added dropwise and the mixture was warmed to rt and stirred overnight. 10% aq NH4Cl was added and the mixture was extracted with EtOAc (3×50 mL). The combined organic layers were washed brine, dried and evaporated. The residue was purified by flash chromatography on silica gel to afford the crude tert-butyl (3S,5S,8S)-8-(benzyloxymethyl)-6-hydroxy-3-((1-(3-methoxypropyl)-1H-indazol-6-yl)methyl)-2,9-dimethyldecan-5-ylcarbamate (1.3 g, 33% yield) as an 11:5 mixture of diastereomers at the alcohol center.

Provenance & Evidence