Regio- and Stereoselective Switchable Synthesis of (<i>E</i>)- and (<i>Z</i>)-<i>N</i>-Carbonylvinylated Pyrazoles

Regio- and Stereoselective Switchable Synthesis of (<i>E</i>)- and (<i>Z</i>)-<i>N</i>-Carbonylvinylated Pyrazoles

Regio- and stereoselective switchable synthesis of (<i>E</i>)- and (<i>Z</i>)-<i>N</i>-carbonylvinylated pyrazoles is first developed by using the Michael addition reaction of pyrazoles and conjugated carbonyl alkynes. Ag<sub>2</sub>CO<sub>3</...

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Bibliographic Details
Main Authors: Xue Zhang, Zheyu Zhang, Haifeng Yu, Guangbo Che
Format: Article
Language:English
Published: MDPI AG 2023-05-01
Series:Molecules
Subjects:
silver carbonate
Michael addition
pyrazoles
alkynes
stereoselectivity
Online Access:https://www.mdpi.com/1420-3049/28/11/4347
Description
Summary:Regio- and stereoselective switchable synthesis of (<i>E</i>)- and (<i>Z</i>)-<i>N</i>-carbonylvinylated pyrazoles is first developed by using the Michael addition reaction of pyrazoles and conjugated carbonyl alkynes. Ag<sub>2</sub>CO<sub>3</sub> plays a key role in the switchable synthesis of (<i>E</i>)- and (<i>Z</i>)-<i>N</i>-carbonylvinylated pyrazoles. Ag<sub>2</sub>CO<sub>3</sub>-free reactions lead to thermodynamically stable (<i>E</i>)-<i>N</i>-carbonylvinylated pyrazoles in excellent yields whereas reactions with Ag<sub>2</sub>CO<sub>3</sub> give (<i>Z</i>)-<i>N</i>-carbonylvinylated pyrazoles in good yields. It is noteworthy that (<i>E</i>)- or (<i>Z</i>)-<i>N</i><sup>1</sup>-carbonylvinylated pyrazoles are obtained with high regioselectivity when asymmetrically substituted pyrazoles react with conjugated carbonyl alkynes. The method can also extend to the gram scale. A plausible mechanism is proposed on the basis of the detailed studies, wherein Ag<sup>+</sup> acts as coordination guidance.
ISSN:1420-3049

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