Cooperative Titanocene and Phosphine Catalysis: Accelerated C鈥揦 Activation for the Generation of Reactive Organometallics

详细信息    查看全文

• 作者：Lauren M. Fleury ; Andrew D. Kosal ; James T. Masters ; Brandon L. Ashfeld
• 刊名：The Journal of Organic Chemistry
• 出版年：2013
• 出版时间：January 18, 2013
• 年：2013
• 卷：78
• 期：2
• 页码：253-269
• 全文大小：679K
• 年卷期：v.78,no.2(January 18, 2013)
• ISSN：1520-6904

文摘

The study presented herein describes a reductive transmetalation approach toward the generation of Grignard and organozinc reagents mediated by a titanocene catalyst. This method enables the metalation of functionalized substrates without loss of functional group compatibility. Allyl zinc reagents and allyl, vinyl, and alkyl Grignard reagents were generated in situ and used in the addition to carbonyl substrates to provide the corresponding carbinols in yields up to 99%. It was discovered that phosphine ligands effectively accelerate the reductive transmetalation event to enable the metalation of C鈥揦 bonds at temperatures as low as 鈭?0 掳C. Performing the reactions in the presence of chiral diamines and amino alcohols led to the enantioselective allylation of aldehydes.