Metal-Free Selective Synthesis of 1,4-Dihydropyridazines from Hydroxypyrrolines and Hydrazines
作者:Dmitrii A. Shabalin、Marina Yu. Dvorko、Evgeniya E. Zolotareva、Igor' A. Ushakov、Alexander V. Vashchenko、Elena Yu. Schmidt、Boris A. Trofimov
DOI:10.1002/ejoc.201700589
日期:2017.7.25
An efficient and selective synthesis of 1,4-dihydropyridazines through the acid-catalyzed recyclization of 5-hydroxy-Δ1-pyrrolines with hydrazines has been developed. The scope of this reaction was thoroughly explored, resulting in the generation of a library of 1,4-dihydropyridazines in good to excellent yields (25 examples, 67–100 % yields).
Functionalized Hexahydropyrrolo[2,1‐
<i>b</i>
]oxazoles from Catalyst‐Free Annulation of Δ
<sup>1</sup>
‐Pyrrolines with Electron‐Deficient Propargylic Alcohols
作者:Ludmila A. Oparina、Dmitrii A. Shabalin、Anastasiya G. Mal'kina、Nikita A. Kolyvanov、Lyudmila A. Grishchenko、Igor' A. Ushakov、Alexander V. Vashchenko、Boris A. Trofimov
DOI:10.1002/ejoc.202000582
日期:2020.7.23
Catalyst‐free annulation of Δ1‐pyrrolines with electron‐deficient propargylic alcohols was demonstrated allowing the formation of functionalized hexahydropyrrolo[2,1‐b ]oxazoles in good to excellent yields.
证实了无电子的炔丙基醇对Δ1-吡咯啉的无催化剂环化反应,可以形成官能化的六氢吡咯并[2,1- b ]恶唑,收率高至优异。
Synthesis of 5-hydroxy-Δ1-pyrrolines from aryl isoalkyl ketoximes and acetylene in a tuned superbase medium
作者:Dmitrii A. Shabalin、Marina Yu. Dvorko、Elena Yu. Schmidt、Nadezhda I. Protsuk、Boris A. Trofimov
DOI:10.1016/j.tetlet.2016.06.025
日期:2016.7
The reactionbetweenaryl isoalkyl ketoximes and acetylene under atmospheric pressure was applied to the synthesis of 5-hydroxy-Δ1-pyrrolines, containing aromatic substituents at the carbon–nitrogen double bond, in moderate yields. A crucial factor for the synthesis is the accurate tuning of the system basicity to prevent further dehydration of the target compounds to 3H-pyrroles.
Hydrazides in the reaction with hydroxypyrrolines: less nucleophilicity – more diversity
作者:Dmitrii A Shabalin、Evgeniya E Ivanova、Igor A Ushakov、Elena Yu Schmidt、Boris A Trofimov
DOI:10.3762/bjoc.17.29
日期:——
Expedient protocols for the synthesis of three types of highly functionalized azaheterocyclic scaffolds (dihydropyridazines, tetrahydropyridazines, and partially saturated tricyclic systems) from readily available hydroxypyrrolines and hydrazides are described. The directions of the transformation of a common initial intermediate, namely a Brønsted acid-activated hydroxypyrroline, depend on the reaction
Recyclization of available 5-hydroxypyrrolines with semicarbazide and its analogues has been studied. As a result, rare 1,4-dihydropyridazines with carboxamide function at the N-1 atom have been synthesized in up to 88% isolated yields.