Synthesis of cyclobutanols
Diastereoselective [2 + 2] cyclizations of silyl enol ethers with acrylates are described. The presence of silicon-silicon bonds of the tris(trimethylsilyl)silyl group proved to be important for this transformation. High diastereoselectivity was achieved by using the bulky bis(2,6-diphenylphenoxide) aluminum triflimide catalyst.
M. B. Boxer, H. Yamamoto, Org. Lett., 2005, 7, 3127-3129.
A [6 + 2] annulation that involves the combination of β-alkenoyl acylsilanes and a vinyllithium derivative enables in one operation and a stereoselective manner the construction of eight-membered ring systems containing useful functionalities for further synthetic elaboration from readily available six- and two-carbon components.
K. Takeda, H. Haraguchi, Y. Okamoto, Org. Lett., 2003, 5, 3705-3707.