Fluorinated Heterocyclic Compounds− The First Example of an Irreversible Ring-Degenerate Rearrangement on Five-Membered Heterocycles by Attack of an External Bidentate Nucleophile
作者:Silvestre Buscemi、Andrea Pace、Ivana Pibiri、Nicolò Vivona、Camilla Zaira Lanza、Domenico Spinelli
DOI:10.1002/ejoc.200300737
日期:2004.3
hydroxylamine in DMF give the regioisomeric 3-perfluoroalkyl-1,2,4-oxadiazoles 4 in excellent yields. This process is the first example of ring-degenerate rearrangement (RDR) occurring on five-membered heterocycles by attack of an external bidentate nucleophile, which replaces two heteroatoms of the ring. We suggest that an ANRORC-like mechanism occurs in which the addition of the nucleophilic nitrogen atom
5-全氟烷基-1,2,4-恶二唑3 与羟胺在DMF 中的反应以优异的产率得到区域异构的3-全氟烷基-1,2,4-恶二唑4。该过程是通过外部双齿亲核试剂的攻击在五元杂环上发生环简并重排 (RDR) 的第一个例子,该亲核试剂取代了环的两个杂原子。我们建议发生类似 ANRORC 的机制,其中在 3 的 C(5) 原子上添加亲核氮原子 (NH2OH),然后通过亲核氧原子的攻击开环和不可逆的环简并闭合(= NOH) 在原始环的 C(3) 原子上,通过 C(3)-C(5) 环形开关实现了 4 的优雅高效合成。对起始材料和最终产品以及建议的中间体进行从头算计算,支持该机制并阐明反应的特征。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)