Convenient synthesis of 3-vinyl and 3-styryl coumarins.

TLDR: Extension of the delocalized π-electron system accomplished by Heck coupling reactions with aryl halides results in an increased fluorescence of the compounds whose applicability is yet to be established.

About: This article is published in Organic Letters.The article was published on 2011-09-15 and is currently open access. It has received 82 citations till now. The article focuses on the topics: Heck reaction & Aryl.

Figures

Table 2. Synthesis of 3-Styryl Coumarins 4 by Palladium Cross-Coupling between 3-Vinyl Coumarins 2 and Aryl Halidesa

Table 1. Yields of 3-Vinyl Coumarins 2 and of Intermediates 1 and 3

Table 3. Absorption and EmissionMaxima, Fluorescence QuantumYield andAverage Fluorescent Lifetime of Selected Coumarins in Acetonitrile Solutions

Frequently asked questions

Q1. What have the authors contributed in "Convenient synthesis of 3-vinyl and 3-styryl coumarins" ?

Coumarins have been extensively investigated with regard to their outstanding optical properties, and therefore they are a powerful tool for the study of simple molecules in complex biological systems. 

Q2. What is the objective of the study?

22With the objective to increase the delocalization of the π-electron system, new vinyl and styryl coumarin derivatives with potential applications, such as fluorescent chemosensors, were developed by a simple and efficient synthetic strategy involving two simple steps. 

Q3. What is the main issue in expanding the applications of coumarin derivatives?

A major issue in expanding the applications of coumarin derivatives is related to their color spectrum and intensity of their spectroscopic bands. 

Q4. What is the simplest way to extend the system?

Based on substitution at position 3 of the benzopyrone ring, these compounds can be divided into two series, one bearing a vinyl substituent at position 3, and the other, with a more extended π system, bearing a styryl group. 

Q5. What is the main purpose of this paper?

General experimental procedure, spectral data and characterization data for new compounds, absorption and emission spectra, and fluorescence decays. 

Q6. What is the yield of compound 2e?

The yield of compound 2e is very lowdue to the fact that compounds 1eand 3e0 can be formed owing to the isomerization of the double bond. 

Q7. What is the way to synthesis coumarins?

18Compound 1a could be converted into the 3-vinyl coumarin16 (2a) in good to moderate yields under treatmentwithpotassium tert-butoxide (Scheme1, pathwayB). 

Q8. What is the difference between coumarin 4g and vinyl?

In the case of coumarin 4g, ΦF and τm are especially low and short, respectively, and the emission maximum occurs above 800 nm (above their instrumental resolution), due to the charge transfer coupling between the electron-donating NEt2 group and electron-withdrawing NO2 group. 

Q9. What is the versatile synthesis of coumarins?

A more versatile synthesis of 3-alkenylcoumarins was achieved by a variety of 2-acyl-, 2-aroyl-, and 2-formylsubstituted phenols on reaction with R,β-unsaturatedcarboxylic acid chlorides.