Cesium carbonate → HCID 86757573, compound

Participants

Reaction Steps

5-Hydroxy-2,2-dimethyl-10-propyl-2H-pyrano[2,3-f]chromen-8-one (Example 8, 107 mg, 0.37 mmol) and caesium carbonate (6 mg, 0.019 mmol) were placed in a flask. A solution of (E)-2-methyl-2-butenyl methyl carbonate (108 mg, 0.75 mmol) in dichloromethane (1 ml) was added. Meanwhile, a solution of (−)-1,2-bis-N-[2′-(diphenylphosphino)benzoyl]-11(S),12(S)-diamino-9,10-dihydro-9,10-ethanoanthracene and then dipalladium tris(dibenzylidineacetone)-chloroform adduct (9.5 mg, 0.025 mmol) in dichloromethane (0.5 mmol) was prepared, then added to the reaction. The suspension was heated to reflux for 8 h, then the yellow solution was allowed to cool to room temperature. After adsorption onto silica (500 mg), and elution with heptane-ethyl acetate (9:1), the (S)-allylic ether in a 11:1 mixture with its allylic regioisomer, i.e. (E2-methyl-2-butenyl)oxy-2,2-dimethyl-10-propyl-2H-pyrano[2,3-f]chromen-8-one, was obtained as a yellow oil (132 mg, 100%); enantiomeric excess 94% by chiral HPLC.

Provenance & Evidence