Silane, trimethyl(2-propyn-1-yloxy)- → (1R*,2R*,5S*,6R*)-8-benzyl-2-(3-hydroxypropynyl)-1-phenyl-6-phenylsulphonyl-8-azabicyclo[3.2.1]octan-2-ol

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Reaction Steps

A solution of n-butyl lithium in hexanes (1.6M, 20 ml, 32 mmol) was added to a stirred, −78° C. solution of O-trimethylsilylpropargyl alcohol (5 ml, 34.8 mmol) in tetrahydrofuran (50 ml). After 30 minutes a solution of (1R*,5S*,6R*)-8-benzyl-1-phenyl-6-phenylsulphonyl-8-azabicyclo[3.2.1]octan-2-one (Description 7; 4.6 g, 10.7 mmol) in tetrahydrofuran (20 ml) was added. The mixture was stirred for 30 minutes then quenched by addition of saturated ammonium chloride. The mixture was diluted with ethyl acetate and washed (2×100 ml) with water. The organic layer was separated and treated with a solution of tetrabutylammonium fluoride (11.5 ml, 1.0M solution in tetrahydrofuran) for 20 minutes at room temperature. The solution was washed with water (2×100 ml) then dried (MgSO4), filtered and concentrated in vacuo. The residue was chromatographed on silica gel eluting with 1:1, 3:2 and 2:1 ethyl acetate/iso-hexanes to yield the title compound (4.12 g, 79%).

Provenance & Evidence