Nazarov cyclizations are catalyzed by a dicationic Ni(II) complex containing the chiral tridentate phosphine Pigiphos; the catalyst exerts a high degree of torquoselectivity and affords the products in up to 88% ee.

A novel base-promoted cascade desalicyloylative dimerization of 3-(1-alkynyl)chromones to produce 2-alkynyl xanthones has been developed. This tandem process involves multiple reactions, such as Michael additions/cyclizations/desalicyloylation without a transition metal catalyst and inert atmosphere.

Functionalized 4- and 6-azaindolines are accessible with high levels of enantioselectivity by the cation-directed cyclization of aminopyridine-derived imines via phase-transfer catalysis. The extension of this methodology to diastereoselective cyclizations is also described.

This paper describes the synthesis of dithioindoles from the free-radical cyclizations of arylisonitriles having pendant alkynes. Also described is the synthesis of substituted indoles and spiro-fused indoles from the coupling of dithioindoles with active hydrogen-containing compounds.

A cationic rhodium(I)/bisphosphine complex catalyzes carboxylative cyclizations of 1,6-diynes, leading to cyclic dienyl carboxylates, in high yields with high chemo-, regio-, and stereoselectivities under mild reaction conditions.

Free radical cyclizations of the 4-phenylbutyl radical and analogues carrying naphthyl and vinyl groups instead of phenyl have been studied. A typical reaction scheme is given below involving closures to fiveand six-membered rings. Competition rate studies for the various types of ring closure were performed with deuterated analogues. The results can be used as an efficient mechanistic tool for...

Similar to propargylic carboxylates and sulphides, 3-propargylindoles undergo 1,2-indole migrations under cationic gold(I) catalysis. The intermediate Au-carbenoid complex may evolve through different pathways depending on the substituents at the propargylic and terminal positions of the alkyne moiety. Thus, 3-indenylindole derivatives were easily obtained through formal iso-Nazarov or Nazarov ...

To access architecturally complex natural products, chemists usually devise a customized synthetic strategy for constructing a single target skeleton. In contrast, biosynthetic assembly lines often employ divergent intramolecular cyclizations of a polyunsaturated common intermediate to produce diverse arrays of scaffolds. With the aim of integrating such biogenetic strategies, we show the devel...