Synthesis of Some Novel Thioxanthenone-Fused Azacrown Ethers, and Their Use as New Catalysts in the Efficient, Mild, and Regioselective Conversion of Epoxides toβ-Hydroxy Thiocyanates with Ammonium Thiocyanate
conditions in various aprotic solvents. Reagents and conditions were identified for the synthesis of individual β-hydroxythiocyanates in high yield and with more than 90% regioselectivity. The results can be discussed in terms of a four-step mechanism (Scheme 2): 1) formation of a complex between catalyst and NH4SCN, 2) release of SCN− from the complex, 3) reaction of the released SCN− at the sterically