Tetrahydrofuran → 7-{(1r,4s,5r)-4-(Tert-butyl-dimethyl-silanyloxy)-5-[(e)-3-(tert-butyl-dimethyl-silanyloxy)-5-(3-chloro-benzo[b]thiophen-2-yl)-pent-1-enyl]-3,3-dimethyl-2-oxo-cyclopentyl}-hept-5-ynoic acid methyl ester

Participants

Reaction Steps

A −78° C. solution of iodide 32 (675 mg, 1.34 mmol) in THF (2.0 mL) was treated with tert-butyllithium (1.73 mL, 2.94 mL, 1.7 M/pentane). The dark red mixture was stirred for 25 min. and then dimethylzinc (0.80 mL, 1.6 mmol, 2 M/toluene) was added. The solution was stirred at 0° C. for 15 min. and then recooled to −78° C. At this time, a solution of enone 6 (208 mg, 0.87 mmol) in THF (1.0 mL) was added over 2 h by syringe pump, rinsing with 0.5 mL THF. After 30 min., HMPA (1.34 mL, distilled from CaH2) was added followed by a solution of propargyl iodide 31 (1.286 g, 4.83 mmol) in THF (1.0 mL). The solution was stirred in a −40° C. bath overnight and then 20 mL saturated ammonium chloride solution and 10 mL water were added. The mixture was extracted with dichloromethane (20 mL) and ethyl acetate (2×20 mL). The combined organic extracts were dried (MgSO4), filtered and evaporated. Purification by flash chromatography on silica gel (5-10% ethyl acetate/hexanes) gave 198 mg (0.27 mmol, 31%) of 33.

Provenance & Evidence