A new palladium(II)-catalyzed [3,3] aza-Claisen rearrangement of 3-allyloxy-5-aryl-1,2,4-oxadiazoles
作者:Gianfranco Fontana、Antonio Palumbo Piccionello
DOI:10.1016/j.tetlet.2010.12.058
日期:2011.2
new efficient palladium(II)-catalyzed [3,3] aza-Claisen, formal sigmatropic rearrangement of 3-allyloxy-5-aryl-1,2,4-oxadiazoles was developed. The mechanism was studied by analyzing the regiochemical and stereochemical course of the reaction. The results obtained indicated the intervention of a cationic pallada-cycle similar to the one postulated for the Coperearrangement of 1,5-dienes.
Studies on azole-to-azole interconversions. Substituent effects on the ring-degenerate equilibration between 3-aroylamino-5-methyl-1,2,4-oxadiazoles and 3-acetylamino-5-aryl-1,2,4-oxadiazoles
involved. In the first case the effect of X is meagre and 3-acetylamino-5-aryl-1,2,4-oxadiazoles are more stable than the 3-aroylamino-5-methyl isomers. Vice-versa, when anions are involved the substituent effect is remarcable and the equilibrium can be, for strongly electron-withdrawing X-groups, even largely shifted towards the anions of the 3-aroylamino-5-methyl-1,2,4-oxadiazoles.
通过1 H NMR测量,已经在CD 3 OD和t BuOK / CD 3 OD中研究了标题反应。已经发现,无论涉及中性或阴离子形式,平衡组成和芳基部分中X-取代基对其施加的作用都完全不同。在第一种情况下,X的作用微不足道,3-乙酰氨基-5-芳基-1,2,4-恶二唑比3-芳酰基氨基-5-甲基异构体更稳定。反之亦然,当涉及阴离子时,取代基的作用是可区分的,并且对于强烈吸电子的X-基团,其平衡甚至可能朝着3-aroylamino-5-methyl-1,2,4-的阴离子转移。恶二唑。
Base-Promoted Tandem S<sub>N</sub>Ar/Boulton–Katritzky Rearrangement: Access to [1,2,4]Triazolo[1,5-<i>a</i>]pyridines
作者:Zihao Li、Kongxi Qiu、Xiao Yang、Wei Zhou、Qian Cai
DOI:10.1021/acs.orglett.2c00863
日期:2022.4.29
A base-promoted tandem SNAr/Boulton–Katritzkyrearrangement is developed. It offers a simple and straightforward method for the formation of functionalized [1,2,4]triazolo[1,5-a]pyridines from 1,2,4-oxadiazol-3-amines or 3-aminoisoxazoles with 2-fluoropyridines.
开发了一种碱基促进的串联 S N Ar/Boulton-Katritzky 重排。它提供了一种从 1,2,4-恶二唑-3-胺或 3-氨基异恶唑与 2-氟吡啶形成官能化 [1,2,4]三唑并[1,5- a ]吡啶的简单直接的方法。
An Alkyne–Isocyanide Cycloaddition/Boulton-Katritzky Rearrangement/Ring Expansion Reaction: Access to 9-Deazaguanines
作者:Jianghao Luo、Haowen Ma、Kaifu Wu、Yunlin Ao、Wei Zhou、Qian Cai
DOI:10.1021/acs.orglett.3c00575
日期:2023.3.31
An alkyne–isocyanide [3 + 2] cycloaddition followed by a Boulton–Katritzky rearrangement and a ring expansion is demonstrated. Different from the typical Boulton-Katritzky rearrangement, which forms five-membered ring products, the rearrangement-ring expansion method provides a mild, efficient, and atom-economical access to fused 9-deazaguanine structures in high yields.