The carbene or carbocationic nature of the intermediates in the gold-catalyzed cycloisomerization of 1,5-enynes can be revealed, depending on the ligands on the gold catalysts. Gold complexes with highly electron-donating ligands promote reactions that proceed via intermediates with carbene-like character, leading to products with a bicyclo[3.1.0]hexene skeleton. The intermediate cyclopropyl endo-gold carbenes formed in this cyclization have been trapped, for the first time, to give biscyclopropane derivatives in a reaction that proceeds in a concerted fashion, according to DFT calculations.

Abstract1,1′‐Binaphthalenes and heterocyclic analogues can be efficiently prepared by palladium‐catalysed cross‐coupling reactions between tri(1‐naphthyl)indium reagents and 1‐halonaphthalenes and haloisoquinolines. The reactions were usually carried out in THF at 80 °C with a slight excess of the indium reagent (40 mol‐%) and a low catalyst loading (4 mol‐% Pd) to afford the cross‐coupling products in good yields (45–99 %). The method allows the synthesis of sterically hindered 2‐substituted and 2,2′‐disubstituted 1,1′‐binaphthalenes and naphthylisoquinolines. In addition, the coupling reactions can be performed enantioselectively and the best enantiomeric excesses were obtained by using the chiral amino‐phosphane ferrocenyl ligand (R,S)‐PPFA.

The palladium-catalyzed cross-coupling reaction of triorganoindium reagents (R3In) with 5-bromo-2-chloropyrimidine proceeds chemoselectively, in good yields, to give 5-substituted-2-chloropyrimidines or 2,5-disubstituted pyrimidines using 40 or 100 mol % of R3In, respectively. Sequential cross-couplings are also performed, in one pot, using two different R3In. This method was used to achieve the first synthesis of the alkaloid hyrtinadine A. The key step was a two-fold cross-coupling reaction between a tri(3-indolyl)indium reagent and 5-bromo-2-chloropyrimidine.

The synthesis and photochemical study of novel nonsymmetrical 1,2-dithienylethenes (DTEs) with a maleimide bridge have been carried out. The synthetic approach to the DTEs was based on successive selective palladium-catalyzed cross-coupling reactions of 5-susbtituted-2-methyl-3-thiophenyl indium reagents with 3,4-dichloromaleimides. The required organoindium reagents were prepared from 2-methyl-3,5-dibromothiophene by a selective (C-5) coupling reaction with triorganoindium compounds (R3 In) and subsequent metal-halogen exchange. The coupling reactions usually gave good yields and have a high atom economy with substoichiometric amounts of R3 In. The results of photochemical studies show that these novel dithienylmaleimides undergo a photocyclization reaction upon irradiation in the UV region and a photocycloreversion after excitation in the visible region, thus they can be used as photochemical switches. ON-OFF operations can be repeated in successive cycles without appreciable loss of effectiveness in the process.