Direct arylations of indoles and pyrroles with differently substituted diaryliodonium salts were shown to efficiently proceed in the absence of metal catalysts.

Two original macrocyclic silver(I)(pyridine-containing ligand) complexes [Ag(I)(Pc-L)] were synthesized and characterized. Their ability to catalyze the coupling among aldehydes, terminal alkynes and amines (A(3)-coupling) was demonstrated. The reaction could be performed under conventional as well as dielectric heating. The catalysts were effective in both cases, but dielectric heating allowed a lower catalyst loading and reduced ratio among reaction partners in shorter reaction times. The reaction scope was broad, including aryl/alkyl aldehydes, aryl/alkyl acetylenes and secondary aliphatic amines. Some unprecedented propargylamines have been prepared. The new catalytic system was also tested with more challenging coupling partners such as aniline and ketones.

The synthesis of 3‐substituted 1‐methylpyrrolo[1,2‐a]pyrazines and 3‐substituted isoquinolines was achieved by the intramolecular cyclisation of 2‐acetyl‐1‐propargylpyrroles and 2‐alkynylbenzaldehydes, respectively, in the presence of ammonia under microwave heating. The tandem imination/annulation of 2‐alkynylbenzaldehydes was easily accomplished under standard conditions, while TiCl4 was used to achieve pyrrolo[1,2‐a]pyrazines. The reaction mechanism and the regioselectivity were discussed on the basis of theoretical calculations and spectroscopic data. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The synthesis of 3-substituted-1-alkoxyisochromenes starting from 2-alkynylbenzaldehydes and different alcohols is reported. The reaction is catalyzed by a silver(I) complex with an original macrocyclic pyridine-containing ligand. The approach is characterized by absolute regioselectivity, mild reaction conditions, good to excellent reaction yields, cleanness of the reaction, and reduced purification steps. The reaction mechanism was investigated by in-depth (1)H NMR experiments and an aimed "trapping" experiment.

A new gold-catalyzed reaction of ynamides with 3-substituted indoles as nucleophiles is reported. The reaction allows for the synthesis of a new class of 2-vinylindole derivatives in good yields via the intermediacy of a cyclopropyl gold-carbenoid species.

Ag old(I)-catalyzed cascade [3,3]-propargylic rearrangement and [4+ +2] cycloaddition reaction of 2-vinylindoles with propargylic estersi sr eported. Ther eactionl eads to the synthesis of highly substituted tetrahydrocarbazole derivatives in high yields and diasteroselectivities. Furthermore,ap reliminary screeningf or an asymmetric version of this reaction is described.

A small library of six polarity-sensitive fluorescent dyes, nicknamed MediaChrom, was prepared. This class of dyes is characterized by a pyrimidoindolone core fitted out with a conjugated push-pull system and a carboxy linker for a conceivable coupling with biomolecules. The optimized eight-step synthetic strategy involves a highly chemo- and regioselective gold-catalyzed cycloisomerization reaction. The photophysical properties of MediaChrom dyes have been evaluated in-depth. In particular, the MediaChrom bearing a diethylamino as an electron-donating group and a trifluoromethyl as an electron-withdrawing group displays the most interesting and advantageous spectroscopic features (e.g., absorption and emission in the visible range and a good quantum yield). Promising results in terms of sensitivity have been obtained in vitro on this dye as a membrane/lipophilic probe and as a peptide fluorescent label.

Screening of reaction conditions for domino addition/annulation IntroductionIn our laboratories, many efforts have been devoted to the synthesis of nitrogen containing rings by sequential addition/annulation reaction of γ-or δ-ketoalkynes in the presence of ammonia. Some years ago, we reported an in-depth investigation on the synthesis of the pyrazino[1,2-a]indole nucleus through the sequential imination/annulation of 2-carbonyl-1-propargylindoles in the presence of ammonia in methanol. 1 This valuable approach has been very recently applied to the synthesis of pyrrolo[1,2-a]pyrazines and isoquinolines starting from 2-acetyl-N-propargyl pyrroles and 2-alkynyl-benzaldehydes, respectively, 2 and the approach to isoquinolines was also successfully transformed in a multicomponent process. 3 But, unexpectedly, when we tried to react 2-alkynylacetophenone derivatives under optimized conditions for the domino process the reaction failed. This result prompted us to investigate the reaction of alynyl ketones more in depth. These are our results…