Synthesis of highly functionalized 2,5-disubstituted pyrrolidines via an aza-Morita–Baylis–Hillman-type reaction

An aza-Morita–Baylis–Hillman-type reaction of Michael acceptors with 5-substituted cyclic N,O-acetals derived from pyrrolidines has been investigated. It has been found that the combination of Me2S and TMSOTf work well with unhindered and reactive enals and enones whilst the use of quinuclidine and TMSOTf is superior for more hindered Michael acceptors. The reactions lead to 2,5-trans-disubstituted pyrrolidines with good to excellent diastereoselectivity. The origin of the selectivity is discussed.