The torquoselectivity theory predicts the direction of ring-opening of a cyclobutene substituted by electron donors and acceptors. See William R. Dolbier, Jr., Henryk Koroniak, K. N. Houk, and Chimin Sheu, Acc. Chem. Res., 1996, 29, 471-477.

This art illustrates some of the research of Prof. Ken Houk's group at UCLA.

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