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Generation and Application of Homoenolate Equivalents Utilizing [1,2]-Phospha-Brook Rearrangement under Brønsted Base
Azusa Kondoh1, Takuma Aoki2, Masahiro Terada1,2
1Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan.
Abstract:
A new method for catalytic generation of a homoenolate equivalent and its application to carbon-carbon bond formation was developed by utilizing the [1,2]-phospha-Brook rearrangement under Brønsted base catalysis. The α-oxygenated allyl anions, which can serve as homoenolate equivalents, were catalytically generated in situ by treating readily available chalcones with diethyl phosphite or the pre-formed 1,2-adducts of diethyl phosphite with chalcones in the presence of a catalytic amount of a phosphazene base, P2-tBu. The resulting allyl anions were subsequently trapped by various electrophiles, including Michael acceptors, imines, and aldehydes, providing the corresponding adducts in good yields with moderate to good diastereoselectivities.
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