title: Titanium(IV)-catalyzed stereoselective synthesis of spirooxindole-1-pyrrolines.
abstract: 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.
authors.affiliation: Department of Chemistry, University of California , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Badillo
authors.forename: Carlos J A
authors.initials: CJ
authors.lastname: Ribeiro
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Annaliese K
authors.initials: AK
authors.lastname: Franz
mesh_terms: D002384:Catalysis; D003374:Coumarins / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008314:Malonates / Q000737:chemistry*; D000078183:Oxindoles; D011763:Pyrrolizidine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry*
chemical_list: D003374:Coumarins; D007211:Indoles; D008314:Malonates; D000078183:Oxindoles; D011763:Pyrrolizidine Alkaloids; D013141:Spiro Compounds; C022960:2-oxindole; D014025:Titanium