Aldol- lactonization mechanism NR NR CCI 3 0 OAC NR OCH Re face of enolate blocked Aldehyde approaches the si face of enolate Dijkstra, G. D. H. Kellog, R. M; Wynberg, H. Svendsen, J. S; Marko, I; Sharpless, K. B J.Am.chem.Soc.1989.111.8069 Cortez, G.S., Tennyson, R L Romo, D.J. Am. Chem. Soc. 2001, 123, 7945Aldol - Lactonization Mechanism Dijkstra, G. D. H.; Kellog, R. M.; Wynberg, H.; Svendsen, J. S.; Marko, I.; Sharpless, K. B. J. Am. Chem. Soc. 1989, 111, 8069. Cortez, G. S.; Tennyson, R. L.; Romo, D. J. Am. Chem. Soc. 2001, 123, 7945. NR3 O H H O NR3 H H O H CCl3 O H NR3 O Cl3C NR3 O O Cl3C O O NR3 Cl3C H N H OAc H N H OCH3 O + * * * * Aldehyde approaches the Si face of enolate * Re face of enolate blocked