Wu Xuesong, Yang Ke, Zhao Yan, Sun Hao, Li Guigen, Ge Haibo
Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, Indiana 46202, USA.
Institute of Chemistry and BioMedical Sciences, Nanjing University, Nanjing 210093, P.R. China.
Nat Commun. 2015 Mar 10;6:6462. doi: 10.1038/ncomms7462.
Cobalt-catalysed sp(2) C-H bond functionalization has attracted considerable attention in recent years because of the low cost of cobalt complexes and interesting modes of action in the process. In comparison, much less efforts have been devoted to the sp(3) carbons. Here we report the cobalt-catalysed site-selective dehydrogenative cyclization of aliphatic amides via a C-H bond functionalization process on unactivated sp(3) carbons with the assistance of a bidentate directing group. This method provides a straightforward synthesis of monocyclic and spiro β- or γ-lactams with good to excellent stereoselectivity and functional group tolerance. In addition, a new procedure has been developed to selectively remove the directing group, which enables the synthesis of free β- or γ-lactam compounds. Furthermore, the first cobalt-catalysed intermolecular dehydrogenative amination of unactivated sp(3) carbons is also realized.
近年来，钴催化的sp(2) C-H键官能化反应因其钴配合物成本低以及该过程中有趣的作用方式而备受关注。相比之下，针对sp(3) 碳的研究则少得多。在此，我们报道了在双齿导向基团的辅助下，通过未活化sp(3) 碳上的C-H键官能化过程，实现钴催化脂肪族酰胺的位点选择性脱氢环化反应。该方法为单环和螺环β-或γ-内酰胺提供了一种直接的合成方法，具有良好至优异的立体选择性和官能团耐受性。此外，还开发了一种选择性去除导向基团的新方法，从而能够合成游离的β-或γ-内酰胺化合物。此外，还实现了首例钴催化的未活化sp(3) 碳的分子间脱氢胺化反应。
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