1-s2.0-S0040403997103811-gr1
C. L. Muller, J. R. Bever, M. A. Dordel, M. M. Kitabwalla, T. M. Reineke, J. B. Sausker, T. R. Seehafer, Y. Li, J. P. Jasinski "Regiochemistry of Intramolecular Photocycloaddition of 1,3-Dioxin-4-ones Tethered Through the Ketal Carbon", Tetrahedron Lett. 1997, 38, 8663-8666.

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