Cyclobutane ring formation by triflic imide catalyzed [2+2]-cycloaddition of allylsilanes

Abstract Cyclobutane forming [2+2]-cycloaddition reactions of allylsilane with electron-deficient olefin is promoted by triflic imide (Tf 2 NH). Triflic imide is converted in situ to silyl triflic imide (R 3 SiNTf 2 ), which serves as the actual catalyst for this process. When these reactions take place at higher than ambient temperatures, thermodynamically more stable anti -cyclobutanes are generated preferentially by equilibration of the initially formed adducts via retro [2+2]-cycloaddition.