Development of Gold-catalyzed [4+1] and [2+2+1]/[4+2] Annulations between Propiolate Derivatives and Isoxazoles
作者:Rajkumar Lalji Sahani、Rai-Shung Liu
DOI:10.1002/anie.201610665
日期:2017.1.19
new gold‐catalyzed annulations of isoxazoles with propiolates have been developed. Most isoxazoles follow an initial O attack on the alkyne to afford a [4+1] annulation product. This process results in a remarkable alkyne cleavage of initial propiolates. Unsubstituted isoxazoles proceed through an N attack step to yield formal [2+2+1]/[4+2] annulation products. These two annulation products arise initially
Gold-Catalyzed Michael-Type Reactions and [4 + 2]-Annulations between Propiolates and 1,2-Benzisoxazoles with Ester-Directed Chemoselectivity
作者:Yashwant Bhaskar Pandit、Rajkumar Lalji Sahani、Rai-Shung Liu
DOI:10.1021/acs.orglett.8b02663
日期:2018.11.2
This work reports gold-catalyzed reactions between 1,2-benzisoxazoles and propiolate derivatives with ester-controlled chemoselectivity. For ethyl propiolates 1′, their gold-catalyzed reactions afforded Michael-type products 4, whereas tert-butyl propiolates 1 preferably underwent [4 + 2]-annulations, further yielding 6H-1,3-oxazin-6-one derivatives 3.
这项工作报告了1,2-苯并恶唑与丙酸酯衍生物之间的金催化反应,并具有酯控制的化学选择性。对于丙酸乙酯1',其金催化的反应得到迈克尔型产物4,而丙酸叔丁酯1优选经历[4 + 2]环化,进一步产生6 H -1,3-恶嗪-6-一衍生物3。
Synthesis of Substituted 2-Pyridones via 6π-Electrocyclization of Dienyl Isocyanates
作者:Xiayun Cheng、Alexandria P. Taylor、Kaicheng Zhu
DOI:10.1021/acs.joc.2c00258
日期:2022.5.6
A one-pot Curtius rearrangement of dienyl carboxylic acids followed by a 6π-electrocyclization process to form substituted 2-pyridone products has been developed. Dienyl isocyanates generated from aliphatic acids were more reactive than their aromatic counterparts. Additionally, substitution patterns of the carboxylic acids had an impact on the efficiency of the cyclization.
The copper-catalyzed reaction of isocyanides (CNCH(2)EWG(1)) 1 with electron-deficient alkynes (RC equivalent to CEWG(2)) 2 gave the 2,4-di-EWG-substituted pyrroles 3 selectively, whereas the phosphine-catalyzed reaction of 1 with 2 afforded the 2,3-di-EWG-subsituted pyrroles 4. Accordingly, regioselective synthesis of substituted pyrroles has been achieved by merely choosing the catalyst.