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A Mild, Diastereoselective Construction of Cyclic and Spirocyclic Ketals Employing a Tandem Photoisomerization/Cyclization Tactic
- Li, Bo, Williams, Brett
D., Smith, Amos B.
- Organic letters 2015 v.17 no.1 pp. 3-5
- Bronsted acids, chemical structure, diastereoselectivity, organic compounds, photoisomerization
- The cyclization of trans-δ-hydroxy enones to cyclic mixed ketals routinely requires superstoichiometric strong acid. By operating under a photoisomerization regime, the cyclization of trans-δ-hydroxy enones proceeds under catalytic Brønsted acid to provide cyclic ketals or unsaturated spiroketals in a highly diastereoselective fashion. A one-pot, two-step protocol was thus developed to provide cyclic methoxy ketals with a free β-hydroxy group for future functionalization.