Titanium(IV)-Catalyzed Stereoselective Synthesis of Spirooxindole-1-pyrrolines
journal contributionposted on 17.12.2015 by Joseph J. Badillo, Carlos J. A. Ribeiro, Marilyn M. Olmstead, Annaliese K. Franz
Any type of content formally published in an academic journal, usually following a peer-review process.
A stereoselective cyclization between alkylidene oxindoles and 5-methoxyoxazoles has been developed using catalytic titanium(IV) chloride (as low as 5 mol %) to afford spiro[3,3′-oxindole-1-pyrrolines] in excellent yield (up to 99%) and diastereoselectivity (up to 99:1). Using a chiral scandium(III)–indapybox/BArF complex affords enantioenriched spirooxindole-1-pyrrolines where a ligand-induced reversal of diastereoselectivity is observed. This methodology is further demonstrated for the synthesis of pyrrolines from malonate alkylidene and coumarin derivatives.