Synthesis of Isocoumarins and α-Pyrones via Electrophilic Cyclization
摘要:
A variety of substituted isocoumarins and alpha-pyrones are readily prepared in excellent yields under very mild reaction conditions by the reaction of o-(1-alkynyl)benzoates and (Z)-2-alken-4-ynoates with ICI, I-2, PhSeCl, p-O2NC6H4SCl, and HI. This methodology accommodates various alkynyl esters and has been successfully extended to the synthesis of polycyclic aromatic and biaryl compounds.
A bromide salt mediated neighboring ester-participated bromocyclization of o-alkynylbenzoates is described here for synthesis of benzil-o-carboxylate. 4-bromoisocoumarins are also reached when phenyl o-alkynylbenzoate is used as the substrate. Mechanism studies suggest that the whole process is comprised by electrophilic bromocyclization and dibromohydration-based ring-opening, and the neighboring
NBS-Mediated Oxygen Transfer Reaction of Carbonyl in Ester: Efficient Synthesis of Benzil-<i>o</i>
-carboxylate Derivative From <i>o</i>
-Alkynylbenzoate
diketonization. A plausible mechanism suggests that a bromo‐incoporated isocoumarin cation is described as an intermediate, and the whole process is constituted by NBS‐mediated electrophilic 6‐endo annulation and oxygen transferreaction through NBS‐mediated oxidative ring‐opening. Water serves as a nucleophile of ring‐opening.
One-pot synthesis of 2-(quinoxalin-2-yl)benzoate through NBS-mediated sequential reaction of 2-alkynylbenozate and aryl-1,2-diamine
作者:Bin Huang、Lele Ma、Guanyinsheng Qiu
DOI:10.1016/j.tetlet.2017.04.063
日期:2017.5
A metal-free route involving a sequential reaction of 2-alknylbenzoate and aryl-1,2-diamine is described for the generation of 2-(quinoxalin-2-yl)benzoate. The sequential reaction combines NBS-mediated diketonization of 2-alknylbenzoate and condensation reaction with aryl-1,2-diamine, and proceeds smoothly under mild reaction conditions and an array of 2-(quinoxalin-2-yl)benzoate is achieved with high
Cy<sub>2</sub>NH·HX-Promoted Cyclizations of <i>o</i>-(Alk-1-ynyl)benzoates and (<i>Z</i>)-Alk-2-en-4-ynoate with Copper Halides to Synthesize Isocoumarins and α-Pyrone
作者:Jin-Heng Li、Yun Liang、Ye-Xiang Xie
DOI:10.1055/s-2006-958960
日期:2007.2
Cy 2 NH·HX was found to improve the cyclization reactions of o-(alk-1 -ynyl)benzoates and (Z)-alk-2-en-4-ynoate with CuX 2 (X = Cl, Br) to synthesize the corresponding 4-haloisocoumarins and 5-bromo-2-pyrone, respectively. In the presence of two equivalents of CuCl 2 , cyclization of methyl2-(2-phenylethynyl)benzoate was conducted smoothly to afford the corresponding desired product in 83% yield after
Synthesis of Isocoumarins and α-Pyrones via Electrophilic Cyclization
作者:Tuanli Yao、Richard C. Larock
DOI:10.1021/jo034308v
日期:2003.7.1
A variety of substituted isocoumarins and alpha-pyrones are readily prepared in excellent yields under very mild reaction conditions by the reaction of o-(1-alkynyl)benzoates and (Z)-2-alken-4-ynoates with ICI, I-2, PhSeCl, p-O2NC6H4SCl, and HI. This methodology accommodates various alkynyl esters and has been successfully extended to the synthesis of polycyclic aromatic and biaryl compounds.