[reaction: see text] The gold-catalyzed reaction of 2-alkynyl-phenylamines with alpha,beta-enones represents a new general one-pot entry into C-3-alkyl-indoles by sequential reactions. Gold-catalyzed sequential cyclization/alkylation, N-alkylation/cyclization, or N-alkylation/cyclization/alkylation reactions leading to different indoles can be directed by changing the 2-alkynyl-phenylamine 1/alpha,beta-enone 3 ratio and the reaction temperature. Unusual gold-catalyzed rearrangement reaction of indoles are observed at 140 degrees C. New gold-catalyzed formation of propargyl-alkyl ether under mild conditions and the hydration reaction of N-acetyl-2-ethynyl-phenylamine are reported.

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)

Abstract:The gold-catalysed direct couplings of indoles 1 and pyrroles 5 with 1,3-dicarbonyls 2 is described. This new method for C À C bond formation allows high functional group tolerance, regioselectivity, and scope under relatively mild conditions. Moreover, the 3-alkenylindoles 3 can be readily available through gold-catalysed sequential cyclization/alkenylation reaction of 2-alkynylanilines derivatives 4 with 1,3-dicarbonyls 2.

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The sequential rhodium-catalyzed addition/lactonization reaction of organoboron derivatives to alkyl 4-hydroxy-2-alkynoates would constitute a novel methodology for the synthesis of 4-aryl/heteroaryl/vinyl-2(5H)-furanones with an excellent control of the regio- and chemoselectivity. The role played by rhodium precatalyst, ligands, reaction medium, and the feature of organoboron derivatives has been explored.