Ethyl diazoacetate → (1S,1aS,6bR)-Ethyl-5-((tert-butyldimethylsilyl)oxy)-1a,6b-dihydro-1H-cyclopropa[b]benzofuran-1-carboxylate

Participants

Reaction Steps

Copper (I) triflate (2:1 complex with toluene, 250 mg, 2.4%) and (S,S)-(±)-2,2-isopropylidenebis(4-tert-butyl)-2-oxazoline (205 mg, 3.4%) were stirred in dichloromethane (15 mL) at ambient temperature under N2 atmosphere for 1 hour. A solution of (benzofuran-5-yloxy)(tert-butyl)dimethylsilane (5.0 g, 20.2 mmol) in dichloromethane (85 mL) was added, followed by a slow addition of ethyl diazoethanoate (40 mL, 380 mmol) during a period of 10 hours using a syringe pump. The mixture was concentrated and purified by column chromatography to afford crude compound (7.3 g) which was used for the next step without any further purification.

Provenance & Evidence