Catalysis is one of the most efficient strategies for identifying new chemical reactions. Usually, a catalytic pathway relies on the interaction of a single catalyst with a single reagent in order to lower the energetic barrier. In some cases the mono-catalytic concept is not enough and other strategies are used, in particular, synergistic catalysis. This consists in the activation of the electrophile and the nucleophile by two different catalysts in order that reaction occur. Based on this idea, we studied the addition of benzoxazoles to Morita-Bayllis-Hillman carbonates (MBH-carbonates) by the use of two different catalysts (Metal Lewis acid and Organic Lewis base). The use of one catalyst doesn't seem enough to make the reaction work. Both catalysts work in a concerted way giving the final compound in high yield. We noticed also that the nature of the metal affects the stereoselectivity of the final compound. Different Metal Lewis acids such as palladium, copper, ytterbium salts afforded a moderate diastereoselectivity, but silver salts showed to be highly diastereoselective (dr: 15:1).

Synergistic catalysis: Highly diastereoselective benzoxazole addition to Morita-Baylis-Hillman carbonates

248th National Meeting (2014)

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