Intramolecular alkene hydroamination and degradation of amidines: divergent behavior of rare earth metal amidinate intermediates12. Issue 21 (5th October 2018)

• Record Type: Journal Article
• Authors: Zhang, Dexing; Liu, Ruiting; Zhou, Xigeng
• Is Part Of: Catalysis science & technology. Volume 8:Issue 21(2018)
• Page Start: 5573
• Page End: 5581
• Publication Date: 2018-10-05
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/c8cy01481g
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : The methods for catalytic intramolecular alkene hydroamination and degradation of amidines have been established. Furthermore, a tandem reconstruction/cyclization of amidines has also been developed. Abstract : Direct N–H addition of amidines to alkenes is a highly valuable but challenging transformation that remains elusive. Now, the intramolecular hydroamidination of N -alkenylamidines is achieved by using a rare earth catalyst, which provides an efficient and atom-economical approach for substituted imidazolines and tetrahydropyrimidines. Moreover, a mild and efficient method for the catalytic degradation of amidines to give amines and nitriles is also developed. Additionally, amidine reconstruction followed by an intramolecular alkene hydroamidination strategy for the synthesis of substituted imidazolines and tetrahydropyrimidines from secondary enamines and inactive amidines has also been established, which may circumvent the need for some unavailable starting materials. The mechanistic studies prove that these reactions proceed via a key lanthanide amidinate intermediate that can undergo substrate- and amine-controlled chemodivergent transformations: intramolecular alkene insertion, nitrile extrusion, amidinate reconstruction, or a combination of the reactions. The results presented here not only demonstrate the synthetic potential and versatility of alkene hydroamidination with substrates, but also provide a good insight into the factors that promote or deter the hydroamidination of alkenes.