Ytterbium Triflate Catalyzed Synthesis of Heterocycles

Ytterbium(III) triflate is an efficient and water-tolerant Lewis acid that has been used as a catalyst for a wide range of organic transformations. Various three-, four-, five-, and six-membered, as well as fused, heterocycles have been synthesized using ytterbium triflate as catalyst in both organic and aqueous solvents. The reaction conditions are relatively mild and the catalyst can be readily recovered from the reaction mixtures to be reused. 1 Introduction 2 Three-Membered Heterocycles 3 Four-Membered Heterocycles 4 Five-Membered Heterocycles 5 Six-Membered Heterocycles 6 Benzo-Fused Heterocycles 7 Non-benzenoid Fused Heterocycles 8 Spiroheterocycles 9 Bridged Heterocycles 10 Conclusion