The Formal Oxidative Addition of Electron-Rich Transoid Dienes to Bromonaphthoquinones.

This work established the idea that a halogen atom, such as bromine, will act as a control element in the regiospecific formation of a new carbon-carbon bond. The addition of the electron-rich end of a transoid diene to a bromojuglone derivative occurred exclusively at the unsubstituted carbon of the quinone. Thus, 2,2-dimethyl-4-methoxy-6-methylene-1,3-dioxa-2-sila-4-cyclohexene (3) and either 2- or 3-bromo-5-hydroxy-1,4-naphthoquinone (1 or 2) afforded the adducts 19 or 20 in 57% or 71% yield. Similarly, 2,2-dimethyl-6-methylene-4-(trimethylsiloxy)-1,3-diox-4-ene (4) and 1 gave 21 in 77% yield