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

HRID 920112Notes

Reaction equation

HRID 920112 reaction equation
[O:1]1[C:5]2[CH:6]=[CH:7][C:8]([O:10][Si:11]([C:14]([CH3:17])([CH3:16])[CH3:15])([CH3:13])[CH3:12])=[CH:9][C:4]=2[CH:3]=[CH:2]1.[N+](=[CH:20][C:21]([O:23][CH2:24][CH3:25])=[O:22])=[N-]>ClCCl.[O-]S(C(F)(F)F)(=O)=O.[Cu+]>[CH2:24]([O:23][C:21]([C@H:20]1[C@H:3]2[C@@H:2]1[O:1][C:5]1[CH:6]=[CH:7][C:8]([O:10][Si:11]([C:14]([CH3:17])([CH3:16])[CH3:15])([CH3:12])[CH3:13])=[CH:9][C:4]=12)=[O:22])[CH3:25]

Participants

5

Reactant 2

HCID 12192Ethyl diazoacetateHCID 68968953(Benzofuran-5-yloxy)(tert-butyl)dimethylsilane

Product 1

HCID 131734886(1S,1aS,6bR)-Ethyl-5-((tert-butyldimethylsilyl)oxy)-1a,6b-dihydro-1H-cyclopropa[b]benzofuran-1-carboxylateYield 108%

Reagents, catalysts & solvents 2

HCID 9813164Copper(I) trifluoromethanesulfonateCatalystHCID 6344DichloromethaneSolvent2×

Procedure

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.

Workup

  1. concentrationThe mixture was concentrated
  2. custompurified by column chromatography

Sources & evidence

ORD record
ord-94fef5bf7c0a448d9ce3925a8c7333c5
Source dataset
uspto-grants-2016_03
Patent number
US09273046B2

Reaction notes

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