Au(I)-Catalyzed Cascade Reaction Involving Formal Double Hydroamination of Alkynes Bearing Tethered Carboxylic Groups: An Easy Access to Fused Dihydrobenzimidazoles and Tetrahydroquinazolines

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• 作者：Nitin T. Patil ; Anil Kumar Mutyala ; Pediredla G. V. V. Lakshmi ; Balakrishna Gajula ; Balasubramanian Sridhar ; Gurava Reddy Pottireddygari ; Tadikamalla Prabhakar Rao
• 刊名：Journal of Organic Chemistry
• 出版年：2010
• 出版时间：September 3, 2010
• 年：2010
• 卷：75
• 期：17
• 页码：5963-5975
• 全文大小：1338K
• 年卷期：v.75,no.17(September 3, 2010)
• ISSN：1520-6904

文摘

A process involving gold(I)-catalyzed formal double hydroamination of alkynes, bearing a tethered carboxylic group, for the synthesis of fused dihydrobenzimidazoles and tetrahydroquinazolines has been developed. A series of transition metal catalysts have been screened for this transformation, and a catalyst system consisting of Ph₃PAuCl (1 mol %) and AgOTf (1 mol %) was found to be the best. The procedure entails the reaction of easily accessible starting materials such as alkynoic acids and 1,2-diaminobenzenes/2-aminobenzylamines in the presence of the catalyst in 1,2-dichloroethane at 100 °C. In the case of α-substituted alkynoic acids, the corresponding products were obtained in high diastereoselectivities; the structure of the diastereomers has been unambiguously characterized by NMR techniques. The mechanism of the reaction is discussed, and the origin of the diastereoselectivities is addressed. It was observed that under the microwave irradiation conditions, the reaction time is significantly shortened (0.5 h).