Intramolecular C.(sp~3)—N Coupling by Oxidation of Benzylic C,N-Dianions

摘要

The ability to effect direct, carbon-nitrogen bond formation between an N—H group and a C(sp~3)—H group by the formal loss of H2 would significantly enhance the existing toolbox of synthetic methods to build complex nitrogen-containing molecules. Such a transformation, particularly involving N,Ndialkyl secondary amines, would complement processes such as reductive amination and would obviate the requirement of a preoxidized coupling partner (e.g., a carbonyl group). Although the Hofmann-Loffler-Freytag (HLF) reac-tion and its associated modern variants'21 offer one such alternative, preoxidation of the nitrogen partner is usually required and success remains limited to the formation of specific ring sizes, For example, although five-membered rings are readily formed using the HLF reaction, six- and seven-membered rings are more difficult to obtain. Thus, a general, one-pot, C(sp~3)-N coupling reaction would be highly desir-able.