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

Cyclobutane forming [2+2]-cycloaddition reactions of allylsilane with electron-deficient olefin is promoted by triflic imide (Tf2NH). Triflic imide is converted in situ to silyl triflic imide (R3SiNTf2), 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.