title: Cyclopropanation with Diazomethane and Bis(oxazoline)palladium(II) Complexes.
abstract: Studies toward the development of an enantioselective diazomethane-based cyclopropanation reagent derived from bis(oxazoline)palladium(II) complexes are reported. Several simple palladium chelates, 2 and 7, in addition to the novel carbon-bound complexes 15 were synthesized and evaluated in the cyclopropanation of various electron-deficient olefins. The X-ray crystal structure of aryl-bis(oxazoline)palladium complex 15c is described. Although all catalysts efficiently affected cyclopropanation, all products were racemic. An intriguing relationship between substitution on the oxazoline ring, particularly the commonly-derivatized 4-position, and catalyst efficiency was discovered. The results are rationalized by either partial or complete bis(oxazoline) decomplexation during the course of the reaction.
authors.affiliation: Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801.
authors.forename: Scott E.
authors.initials: SE
authors.lastname: Denmark
authors.forename: Robert A.
authors.initials: RA
authors.lastname: Stavenger
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Faucher
authors.forename: James P.
authors.initials: JP
authors.lastname: Edwards