A variety of biologically and synthetically useful 3-alkenyloxindoles were rapidly synthesised via an SN2′-type allylic substitution reaction of isatin-derived Morita–Baylis–Hillman carbonates with sodium sulfinates. The syntheses were conducted under catalyst-free reaction conditions and good to excellent product yields (up to 96%) and Z/E selectivities (up to >20:1) were obtained.
An efficient, pyridine-free protocol has been developed for the protection of 3°-allyl alcohol of oxindole using a mild base of potassium carbonate under microwave irradiation conditions. The methodology has been tested with a variety of substrates and protecting group reagents, which provides a clean and good yield of desired products within a short reaction time.