A gold‐catalyzed reaction of phenylene‐tethered allenynes with benzofurans gave 1‐(naphth‐1‐yl)cyclopropa[b]benzofuran derivatives, whereas the reaction of 1‐allenyl‐2‐ethynyl‐3‐methylbenzene derivatives in the absence of benzofurans gave acenaphthenes in good yields. These results can be rationalized by nucleophilic attack of the alkyne moiety on an activated allene to form a vinyl cation intermediate.

An ovel approach to the direct construction of tricyclic nitrogen heterocycles based on gold-catalyzed cascade cyclization of aminoallenynes is described. The expected biscyclization reaction of hydroxyisobutyryl-protected aminoallenynes was efficiently promoted by ac atalytic amount of BrettPhosAuNTf 2 in the presence of iPrOH to produce 1,2dihydrobenzo[cd]indole derivatives in good yields.W hen the reaction was combined with Friedel-Crafts acylation or palladium-catalyzed N-arylation, the resulting tricyclic products were efficiently converted into nitrogen-containing polycyclic aromatic compounds (N-PACs) with highly conjugated p-electron systems.Anewly obtained hexacyclic indolium salt showed characteristic concentration-dependent absorption and emission properties. Scheme 1. Gold(I)-catalyzed reactions of diynes and related compounds proceedingvia vinyl cation intermediates.

Ag old-catalyzed reaction of phenylene-tethered allenynes with benzofurans gave 1-(naphth-1-yl)cyclopropa-[b]benzofuran derivatives,whereas the reaction of 1-allenyl-2ethynyl-3-methylbenzene derivatives in the absence of benzofurans gave acenaphthenes in good yields.These results can be rationalized by nucleophilic attackofthe alkyne moiety on an activated allene to form av inyl cation intermediate.

An ovel approach to the direct construction of tricyclic nitrogen heterocycles based on gold-catalyzed cascade cyclization of aminoallenynes is described. The expected biscyclization reaction of hydroxyisobutyryl-protected aminoallenynes was efficiently promoted by ac atalytic amount of BrettPhosAuNTf 2 in the presence of iPrOH to produce 1,2dihydrobenzo[cd]indole derivatives in good yields.W hen the reaction was combined with Friedel-Crafts acylation or palladium-catalyzed N-arylation, the resulting tricyclic products were efficiently converted into nitrogen-containing polycyclic aromatic compounds (N-PACs) with highly conjugated p-electron systems.Anewly obtained hexacyclic indolium salt showed characteristic concentration-dependent absorption and emission properties. Scheme 1. Gold(I)-catalyzed reactions of diynes and related compounds proceedingvia vinyl cation intermediates.