Cobalt-catalyzed regioselective syntheses of indeno[2,1-: C] pyridines from nitriles and diynes bearing propargyl fragments
A highly efficient CoI2/o-phenanthroline catalyzed cycloaddition reaction of diynes bearing TBS protected propargylic alcohol fragments with nitriles has been developed. This methodology offers regioselective access, with good functional group tolerance, to various indeno[2,1-c]pyridine derivatives in moderate to excellent yields. It was found that o-phenanthroline as a bidentate nitrogen ligand showed high efficacy in this cycloaddition reaction.
Highly regioselective synthesis of 1,3-diiodonaphthalene derivatives via a sequential cascade iodocyclization
A novel and flexible sequentially cascade iodocyclization for the synthesis of highly substituted 1,3-diiodinated naphthalene derivatives in up to 99% yield under mild conditions is reported. The dihalogenated moiety can be readily introduced into the naphthalenes in a position that is usually not easily functionalized.
Gold-catalyzed cascade friedel-crafts/furan-yne cyclization/heteroenyne metathesis for the highly efficient construction of phenanthrene derivatives
A rapid access to highly substituted phenanthrenyl ketones through gold-catalyzed cyclization of 1,6-diyn-4-en-3-ols with furans has been developed. Gold catalysts are effective to catalyze three cascade processes involving Friedel-Crafts/furan-yne cyclization/heteroenyne metathesis through C-O bond and alkyne activation. This method offers several advantages such as high selectivities and easily accessible starting materials.
Chen, Yifeng,Li, Guijie,Liu, Yuanhong
supporting information; experimental part
p. 392 - 400
(2011/04/22)
A surprising switch from the Myers-Saito cyclization to a novel biradical cyclization in enyne-allenes: Formal diels-alder and ene reactions with high synthetic potential
If there is an aryl substituent on the acetylene terminus of enyne allenes, then its reaction mode may be changed from the Myers-Saito cyclization to a novel C2-C6 cyclization resulting in a net intramolecular Diels-Alder or ene reaction. As a consequence, the thermal cyclization of readily accessible acyclic enyne allenes can be utilized for the synthesis of complex benzofulvene and benzofluorene derivatives. Kinetic results of the C2-C6 cyclization reaction indicate a two-step reaction pathway with a benzofulvene biradical intermediate.
Schmittel, Michael,Keller, Manfred,Kiau, Susanne,Strittmatter, Marc
p. 807 - 816
(2007/10/03)
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