copper‐catalyzed cross‐coupling of 1,2‐dihaloalkenes and amides leads to cyclic β‐haloenamides, which can participate in a second cross‐coupling reaction to efficiently synthesize highly functionalized cyclic enamides. The selectivity of the intramolecular coupling between exo‐ and endocyclic regioisomers is a crucial synthetic factor and can be influenced by the structure of the substrate and the reaction conditions
A Domino Copper-Catalyzed C-N and C-O Cross-Coupling for the Conversion of Primary Amides into Oxazoles
作者:Frank Glorius、Kerstin Schuh (née Müller)
DOI:10.1055/s-2007-983782
日期:2007.7
A variety of oxazoles can efficiently be prepared, in a single step and in good yield, from primaryamides and 1,2-dihaloalkenes using copper-catalysis. This new method allows the re-gioselective formation of a range of substituted oxazoles. The required 1,2-dihaloalkenes can prepared by simple treatment of alkynes with elemental bromine or iodine.
Acetylenes were stereoselectively brominated with molecular bromine adsorbed on graphite in dichloromethane to produce (E)-α,β-dibromoalkenes; isomerization of the E-isomer to the Z-isomer, usually catalyzed by bromine, did not occur in the presence of graphite.
This invention deals with new unsaturated ester-amides of .alpha.,.beta.-unsaturated polycarboxylic acids derived from halogenated alcohols of the formula ##EQU1## wherein R is a divalent hydrocarbon moiety having at least one and no more than 10 carbon atoms, X is a member selected from the class of bromine and chlorine, and R' is a member selected from the class of hydrogen and a monovalent hydrocarbon containing at least one and no more than 20 carbon atoms. Typical ester-amides are the maleates, fumarates, itaconates and citraconates. These monomers possess fire-retardant properties and are useful for the synthesis of polymers and copolymers.