Reactivity of the TMM entity in the cyclopentene series - Observation of areversed regioselectivity in palladium-catalyzed [3+2] cycloadditions

The first examples of palladium(0)-catalyzed [3+2] cycloadditions involving an electron-deficient olefin and a TMM entity incorporated into a five-mem bered ring are described. In the case of gem-dimethyl precursor 7b, the reg ioselectivity is completely reversed, compared to that traditionally observ ed in these reactions (products 12M and 12m). Additional results and an int erpretation of these findings are given.