title: Highly regioselective copper-catalyzed cis- and trans-1-propenyl Grignard cleavage of hindered epoxides. application in propionate synthesis.
abstract: Hindered protected and unprotected epoxy alcohols were regioselectively cleaved using copper-catalyzed cis- and trans-1-propenylmagnesium bromide. The reaction exhibited good yield and excellent regioselectivity in systems where organocuprates and organoalanes failed. The cis Grignard reagent displayed no double-bond isomerization, whereas the trans isomer showed partial trans-to-cis equilibration, which was minimized by controlling the reagent formation conditions. The reaction was shown to be highly useful for the elaboration of the C10-C15 Streptovaricin D ansa chain fragment.
authors.affiliation: Department of Chemistry, University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, San Juan, Puerto Rico 00931-3346.
authors.forename: David
authors.initials: D
authors.lastname: Rodríguez
authors.forename: Marlenne
authors.initials: M
authors.lastname: Mulero
authors.forename: José A
authors.initials: JA
authors.lastname: Prieto
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D011422:Propionates / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D000480:Alkynes; D004852:Epoxy Compounds; D011422:Propionates; D003300:Copper; C013658:propylene; C029658:propionic acid