Biswas Sovan, Bheemireddy Narendraprasad Reddy, Bal Mathias, Van Steijvoort Ben F, Maes Bert U W
Organic Synthesis, Department of Chemistry , University of Antwerp , Groenenborgerlaan 171 , B-2020 , Antwerp , Belgium.
J Org Chem. 2019 Oct 18;84(20):13112-13123. doi: 10.1021/acs.joc.9b02299. Epub 2019 Oct 7.
An efficient strategy for the cleavage of the picolinamide directing group (DG) and recycling of the byproduct generated has been developed. In this protocol, picolinamides were first Boc activated into tertiary -Boc--substituted picolinamides. These were then cleaved via a Ni-catalyzed esterification reaction with EtOH to give valuable -Boc protected amines. Ni(cod) was used as a catalyst without any ligands or base additives. The byproduct, ethyl 2-picolinate can be used to install the picolinamide DG in a direct or indirect manner on amines. The protocol exhibits a broad functional group tolerance and high yields. To demonstrate the utility of this approach, it was applied on many selected examples from the recent C-H functionalization literature featuring 2-picolinamide as a DG.
已开发出一种用于裂解吡啶甲酰胺导向基团（DG）并回收所产生副产物的有效策略。在此方案中，吡啶甲酰胺首先被Boc活化成叔丁氧羰基（Boc）取代的吡啶甲酰胺。然后通过与乙醇的镍催化酯化反应将这些化合物裂解，得到有价值的Boc保护胺。使用Ni(cod)作为催化剂，无需任何配体或碱添加剂。副产物2-吡啶甲酸乙酯可用于以直接或间接方式将吡啶甲酰胺导向基团安装在胺上。该方案具有广泛的官能团耐受性和高产率。为了证明这种方法的实用性，它被应用于最近以2-吡啶甲酰胺作为导向基团的C-H官能化文献中的许多选定实例。
