Gold(I)-Catalyzed Intermolecular Hydroarylation of Alkenes with Indoles under Thermal and Microwave-Assisted Conditions

• Published in: Chemistry : a European journal Vol. 14; no. 27; pp. 8353 - 8364
• Main Authors: Wang, Ming-Zhong, Wong, Man-Kin, Che, Chi-Ming
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 19.09.2008; WILEY‐VCH Verlag; Wiley
• Subjects: Alkadienes - chemical synthesis; Alkadienes - chemistry; Alkadienes - radiation effects; Alkenes - chemistry; Alkenes - radiation effects; Catalysis; Chemistry; Chemistry, Multidisciplinary; Cycloparaffins - chemical synthesis; Cycloparaffins - chemistry; Cycloparaffins - radiation effects; CC coupling; gold; homogeneous catalysis; hydroarylation; Indoles - chemical synthesis; Indoles - chemistry; Indoles - radiation effects; Microwaves; Molecular Structure; Organogold Compounds - chemistry; Physical Sciences; Science & Technology; Stereoisomerism; synthetic methods; Temperature; C-C coupling; CARBON; ALKYLATION; GOLD-CATALYZED CYCLIZATION; INTRAMOLECULAR HYDROAMINATION; PLATINUM; METHYL MIGRATION; ALKYNES; UNACTIVATED ALKENES; gold; FUNCTIONALIZATION; homogeneous catalysis; hydroarylation; synthetic methods
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200800040

An efficient method for intermolecular hydroarylation of aryl and aliphatic alkenes with indoles using a combination of [(PR3)AuCl]/AgOTf as catalyst under thermal and microwave‐assisted conditions has been developed. The gold(I)‐catalyzed reactions of indoles with aryl alkenes were achieved in toluene at 85 °C over a reaction time of 1–3 h with 2 mol % of [(PR3)AuCl]/AgOTf as catalyst. This method works for a variety of styrenes bearing electron‐deficient, electron‐rich, and sterically bulky substituents to give the corresponding products in good to high yields (60–95 %). Under microwave irradiation, coupling of unactivated aliphatic alkenes with indoles gave the corresponding adducts in up to 90 % yield. Selective hydroarylation of terminal CC bond of conjugated dienes with indoles gave good product yields (62–81 %). On the basis of deuterium‐labeling experiments, a reaction mechanism involving nucleophilic attack of Au(I)‐coordinated alkenes by indoles is proposed. Gold catalysis: Phosphine gold(I) complexes [(PR3)AuCl], in conjunction with silver triflate (AgOTf), catalyze intermolecular hydroarylation of aryl and aliphatic alkenes and conjugated dienes with indoles under thermal and microwave‐assisted conditions. This synthetic protocol provides convenient access to a variety of C3‐alkylated indoles under mild reaction conditions (see scheme).