Table 3. Reaction scope for the construction of chiral bridged [4.2.1] lactones 2-ent ^a .

^aReaction conditions: 5 (0.2 mmol), HNTf₂ (0.06 mmol), water (0.3 mmol), dry DCE (2 mL), 30 °C, in vials; yields are those for the isolated products; determined by HPLC analysis.

^b40 °C, 20 min.

^c30 min.

^dUsing (R)-configured ynamide 5d′ as the substrate.