Oxyanion Steering and CH− π Interactions as Key Elements in an N-Heterocyclic Carbene-Catalyzed [4+ 2] Cycloaddition
SE Allen, J Mahatthananchai, JW Bode…
文献索引：Allen, Scott E.; Mahatthananchai, Jessada; Bode, Jeffrey W.; Kozlowski, Marisa C. Journal of the American Chemical Society, 2012 , vol. 134, # 29 p. 12098 - 12103
The N-heterocyclic carbene catalyzed [4+ 2] cycloaddition has been shown to give γ, δ- unsaturated δ-lactones in excellent enantio-and diastereoselectivity. However, preliminary computational studies of the geometry of the intermediate enolate rendered ambiguous both the origins of selectivity and the reaction pathway. Here, we show that a concerted, but highly asynchronous, Diels–Alder reaction occurs rather than the stepwise Michael-type ...
