1,8-Diazabicyclo(5.4.0)undec-7-ene → (E)-Methyl 2-diazo-4-phenylbut-3-enoate

Participants

Reaction Steps

Methyl (E)-2-diazo-4-phenyl-3-butenoate (9) was prepared according to the procedure described in Davies, et al., J. Org. Chem., 56:3817 (1997) (“Davies II”), which is hereby incorporated by reference). The scheme is set forth in FIG. 7B. Briefly, to a stirred solution of methyl trans-4-phenylbut-3-enoate (1.0 g, 5.68 mmol) and p-ABSA (1.64 g, 6.82 mmol) in CH3CN (150 mL) cooled to 0° C., was added DBU (0.95 g, 6.25 mmol) in one portion. The reaction mixture was allowed to warm to room temperature over 7 h then quenched with saturated ammonium chloride (NH4Cl). The aqueous layer was extracted with diethyl ether, and the combined organic layers were washed with brine and dried (Na2SO4). The solvent was removed under reduced pressure, and the residue was triturated with a solution of pentane/diethyl:ether (1:1). The solid was filtered off, and the solvent was removed under reduced pressure. The residue was purified by flash chromatography (SiO2, pentane/diethyl:ether (15:1)) to give methyl (E)-2-diazo-4-phenyl-3-butenoate (9) (0.92 g, 80% yield) as an orange oil, which was stored neat at −10° C. until ready for use. The spectroscopic data are consistent with previously reported data ((Davies II, which is hereby incorporated by reference).

Provenance & Evidence