title: Solid-phase synthesis of an isoxazolinopyrrole library.
abstract: A four-step solid-phase synthesis of isoxazolinopyrroles 8 that employs an acid-labile 2-(4-formyl-3-methoxyphenoxy)ethyl polystyrene HL resin 1 is reported. Resin-bound vinyl sulfone 5 is obtained by DIC coupling with acid 4, which was in turn synthesized in solution phase by a regioselective nitrile oxide 1,3-dipolar cycloaddition. The resin-bound pyrrole 7 was synthesized on solid phase by pyrrole annulation with various isocyano derivatives and potassium t-butoxide in which the sulfone alpha-anion generated by Michael addition gives the desired pyrrole through internal condensation followed by a sigmatropic [1,5]-hydrogen shift. The resulting isoxazolinopyrroles 8 were released from resin 7 by 10% TFA in moderate to excellent overall yields from 2-(4-formyl-3-methoxyphenoxy)ethyl polystyrene HL resin 1.
authors.affiliation: Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616-5295, USA.
authors.forename: Sung Hee
authors.initials: SH
authors.lastname: Hwang
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Kurth