Rhodium-Catalyzed Atroposelective [2 + 2 + 2] Cycloaddition of Ortho-Substituted Phenyl Diynes with Nitriles: Effect of Ortho Substituents on Regio- and Enantioselectivity

详细信息    查看全文

• 作者：Kenichi Kashima ; Kota Teraoka ; Hidehiro Uekusa ; Yu Shibata ; Ken Tanaka
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：May 6, 2016
• 年：2016
• 卷：18
• 期：9
• 页码：2170-2173
• 全文大小：334K
• 年卷期：0
• ISSN：1523-7052

文摘

Axially chiral 3-(2-halophenyl)pyridines were successfully synthesized in high yields with excellent enantioselectivity by the cationic rhodium(I)/(S)-H₈–BINAP complex-catalyzed atroposelective [2 + 2 + 2] cycloaddition of (o-halophenyl)diynes with nitriles. Interestingly, regio- and enantioselectivity highly depend on ortho substituents on the phenyl group of diynes. When the ortho substituents were methoxy and methoxycarbonyl groups, axially chiral 3-arylpyridines were obtained as a major product, while enantioselectivity was lowered significantly. On the other hand, when the ortho substituents were alkyl groups, regioselectivity was switched to give achiral 6-arylpyridines in high yields.