Scheme 2. Scope of heterocycle-containing cyclopropanes including the chiral auxiliary (R)-pantolactone. Reaction was run on 0.20 mmol scale at room temperature using aryldiazoacetate (1.0 equiv.), vinyl-heterocycle (2.0 equiv.) and 1.0 mol% Rh₂(oct)₄ (0.2 μmol) with CH₂Cl₂ as solvent.