Highly enantioselective [3+2] annulation of Morita-Baylis-Hillman adducts mediated by L-threonine-derived phosphines: synthesis of 3-spirocyclopentene-2-oxindoles having two contiguous quaternary centers
Department of Chemistry & Medicinal Chemistry Program, Life Sciences Institute, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.