title: Rh(II)-Catalyzed Reactions of Diazoesters with Organozinc Reagents.
abstract: Rh(II)-catalyzed reactions of diazoesters with organozinc reagents are described. Diorganozinc reagents participate in reactions with diazo compounds by two distinct, catalyst-dependent mechanisms. With bulky diisopropylethyl acetate ligands, the reaction mechanism is proposed to involve initial formation of a Rh-carbene and subsequent carbozincation to give a zinc enolate. With Rh2(OAc)4, it is proposed that initial formation of an azine precedes 1,2-addition by an organozinc reagent. This straightforward route to the hydrazone products provides a useful method for preparing chiral quaternary α-aminoesters or pyrazoles via the Paul-Knorr condensation with 1,3-diketones. Crossover and deuterium labeling experiments provide evidence for the mechanisms proposed.
authors.affiliation: Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: Panish
authors.affiliation: Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Ramajeyam
authors.initials: R
authors.lastname: Selvaraj
authors.affiliation: Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Fox
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D006835:Hydrazones / Q000138:chemical synthesis; D007202:Indicators and Reagents; D007659:Ketones / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D006835:Hydrazones; D007202:Indicators and Reagents; D007659:Ketones; D009942:Organometallic Compounds; C030011:carbene; D012238:Rhodium; D015032:Zinc; D008697:Methane