Whereas 18 is a bench-stable substrate, repeated attempts to utilize derivatives of the protected primary alcohol in subsequent couplings were plagued by immediate elimination to unsaturated butenolide 21 (see SI for details). This inherent tendency to eliminate was embraced as described below. In fact, clean elimination of the -OTBS functionality with DBU delivered nearly quantitative yield of 21. This set the stage for a pivotal sequence involving 1,6-conjugate addition followed by asymmetric proton transfer.