2-Cyclopenten-1-one → Ethyl 2-oxobicyclo[3.1.0]hexane-6-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a suspension of (ethoxycarbonylmethyl)dimethylsulfonium bromide (148.5 g, 0.648 mole) in acetonitrile (1170 ml) was added 1,8-diazabicyclo[5.4.0]undec-7-ene (97 ml, 0.648 mole) at 22° C. and stirring was continued for 45 min. The solution was treated with 2-cyclopenten-1-one (63 ml, 0.778 mole) and stirring was continued at 22° C. and light exclusion for 4 d. The mixture was evaporated to a volume of ca. 500 ml, partitioned between 1N aqueous HCl and diethylether, the organic layer was dried, evaporated and purified over silica (150 g) using cyclohexane/AcOEt (9:1). The material was dissolved in diethylether (50 ml) and n-pentane (50 ml), briefly cooled to −78° C. until the material precipitated, filtered and the residue was dried to give the title compound as white crystals.

Provenance & Evidence