Mononuclear Heterocyclic Rearrangement: Synthesis of [5:5] Bicyclic [c]-Fused 3- Aminopyrazoles via the N-N Bond Formation Strategy
作者:Leroy B. Townsend、David A. Berry、Tun-Cheng Chien
DOI:10.3987/com-04-10144
日期:——
bicyclic heterocyclic ring systems containing [c]pyrazoles, i.e. imidazo[4,5-c]pyrazole, pyrazolo[3,4-c]pyrazole, pyrrolo-[2,3-c]pyrazole, and pyrazolo[3,4-d][1,2,3]triazole, was accomplished by mononuclear heterocyclic rearrangement (MHR). The core pyrazole ring was formed based on a N-N bond formation strategy. The ring transformation of 5-substituted 3-(2-aminoaryl)-1,2,4-oxadiazoles (14, 15a-b, 16b and
形成含有[c]吡唑的[5:5]双环杂环体系,即咪唑并[4,5-c]吡唑、吡唑并[3,4-c]吡唑、吡咯并-[2,3-c]吡唑,吡唑并[3,4-d][1,2,3]三唑是通过单核杂环重排(MHR)完成的。基于NN键形成策略形成核心吡唑环。5-取代的 3-(2-氨基芳基)-1,2,4-恶二唑 (14, 15a-b, 16b 和 33) 在热条件下转化为相应的 [5:5] 双环 [c]-稠合氢化钠在 DMF 或 DMSO 中促进了 3-氨基吡唑环系统(分别为 17a、18a-b、20 和 34)。MHR的环转化为3-氨基咪唑-[4,5-c]吡唑(4)、3-氨基吡唑并[3,4-c]吡唑(5)、3-的衍生物提供了一种实用通用的合成方法。氨基吡咯并[2,3-c]-吡唑(6)和6-氨基吡唑[3,