Published as part of the Special Topic Modern Strategies for Heterocycles Synthesis

Abstract

Umpolung Amide Synthesis (UmAS) has emerged as a superior alternative to conventional amide synthesis methods based on carbonyl electrophiles in a range of situations, particularly when epimerization-prone couplings are prescribed. In an unanticipated development during our most recent studies, we discovered that diacyl hydrazide products from UmAS were not formed as intermediates when using an acyl hydrazide as the amine acceptor. This resulted in a new preparation of 1,3,4-oxadiazoles from α-bromonitroalkane donors. We hypothesized that a key tetrahedral intermediate in UmAS was diverted toward a more direct pathway to the heterocycle product rather than through formation of the diacyl hydrazide, a typical oxadiazole progenitor. In studies reported here, diversion to 1,2,4-triazole products is described, a behavior hypothesized to also result from an analogous tetrahedral intermediate, but one formed from heteroaromatic hydrazine acceptors.

Umpolung Amide Synthesis (UmAS) has emerged as a superior alternative to conventional amide synthesis methods based on carbonyl electrophiles in a range of situations, particularly when epimerization-prone couplings are prescribed. In an unanticipated development during our most recent studies, we discovered that diacyl hydrazide products from UmAS were not formed as intermediates when using an acyl hydrazide as the amine acceptor. This resulted in a new preparation of 1,3,4-oxadiazoles from α-bromonitroalkane donors. We hypothesized that a key tetrahedral intermediate in UmAS was diverted toward a more direct pathway to the heterocycle product rather than through formation of the diacyl hydrazide, a typical oxadiazole progenitor. In studies reported here, diversion to 1,2,4-triazole products is described, a behavior hypothesized to also result from an analogous tetrahedral intermediate, but one formed from heteroaromatic hydrazine acceptors.

中文翻译：

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1,3,4-恶二唑和杂芳族化合物1,2,4-三唑的转移U杂酰胺合成

作为“杂环合成的现代策略”专题的一部分发布

抽象的

在许多情况下，特别是在规定了易于发生差向异构的偶联时，Umpolung酰胺合成（UmAS）已成为基于羰基亲电试剂的常规酰胺合成方法的优良替代品。在我们最近的研究中出乎意料的发展中，我们发现当使用酰肼作为胺受体时，不会形成来自UmAS的二酰肼产物作为中间体。这导致了从α-溴硝基烷烃供体的新制备1,3,4-恶二唑。我们假设UmAS中的关键四面体中间体被转移到通往杂环产物的更直接途径，而不是通过形成典型的恶二唑祖先二酰基酰肼。在此处报道的研究中，描述了转移至1,2,4-三唑产物的方法，

在许多情况下，特别是在规定了易于发生差向异构的偶联时，Umpolung酰胺合成（UmAS）已成为基于羰基亲电试剂的常规酰胺合成方法的优良替代品。在我们最近的研究中出乎意料的发展中，我们发现当使用酰肼作为胺受体时，不会形成来自UmAS的二酰肼产物作为中间体。这导致了从α-溴硝基烷烃供体的新制备1,3,4-恶二唑。我们假设UmAS中的关键四面体中间体被转移到通往杂环产物的更直接途径，而不是通过形成典型的恶二唑祖先二酰基酰肼。在此处报道的研究中，描述了转移至1,2,4-三唑产物的方法，