Rhodium(II)-Catalysed Intramolecular O-H Insertion of alpha-Diazo-gamma-Azido-delta-Hydroxy-beta-Ketoesters: Evidence for a Novel Sigmatropic Rearrangement of an Allylic Azide Intermediate

The Rh2(OAc)4 catalyzed intramolecular O-H insertion reaction of delta-hydroxy-alpha-diazoesters affords 3(2H)-furanone-2-carboxylates in good yield but with moderate selectivity (d.e. ca 60%). The initially formed 2,5-substituted cis-furanones were found to epimerize to the corresponding 2,5-trans isomers when subjected to silica gel chromatography. The Rh2(OAc)4 catalyzed decomposition of gamma-azido-delta-hydroxy-alpha-diazoesters also furnished 3(2H)-furanone-2-carboxylates. These compounds are derived by a sequential O-H insertion reaction followed by a concerted [3,3]-sigmatropic shift of the allylic azide intermediate

N-[(2-Chloro-3-quinol­yl)meth­yl]-4-fluoro­aniline

In the title compound, C16H12ClFN2, the dihedral angle between the quinoline ring system and the flourophenyl ring is 86.70 (4)°. In the crystal, mol­ecules are linked into chains along the a axis by N—H⋯N hydrogen bonds. In addition, C—H⋯π inter­actions involving the two benzene rings are observed

Synthesis of Polycyclic Ring Systems Using Transition Metal Catalyzed Cyclizations of Diazo Alkynyl Ketones

The rhodium(II)-catalyzed reaction of α-diazo ketones bearing tethered alkyne units represents a new and useful method for the construction of a variety of substituted cyclopentenones. The process proceeds by addition of the rhodium-stabilized carbenoid onto the acetylenic π-bond to give a vinyl carbenoid intermediate. The resulting rhodium complex undergoes a wide assortment of reactions including cyclopropanation, 1,2-hydrogen migration, CH-insertion, addition to tethered alkynes and ylide formation. When 2-alkynyl-2-diazo-3-oxobutanoates were treated with a Rh(II)-catalyst, furo[3,4-c]furans were formed in excellent yield

Heterocyclic Compounds

viii;ill.;940hal.;26c

Gold- and silver-mediated cycloisomerizations of N-propargylamides

Substituted N-propargylamides have proven to be valuable substrates for alkyne-activated cycloisomerization reactions. N-Tosyl-N'-propargylurea underwent reaction with AuCl3 to give the corresponding dihydroimidazolone, while N-propargyl-3-oxobutanamides and esters were used to construct furanyl fused pyrrolldinones and dihydrofuranones via Ag(I)-mediated alkyne activation