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Published on: May 26, 2019
Modified Shapiro reactions with bismesitylmagnesium as an efficient base reagent
William J Kerr1, Angus J Morrison, Marek Pazicky
1Department of Pure and Applied Chemistry, WestCHEM, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, Scotland, UK. w.kerr@strath.ac.uk
Bismesitylmagnesium effectively mediates the Shapiro reaction for synthesizing functionalized styrenes from tosylhydrazones. This magnesium-based method provides high yields and electrophile incorporation, offering an efficient alternative to traditional lithium reagents.
Area of Science:
- Organic Chemistry
- Organometallic Chemistry
Background:
- The Shapiro reaction is a valuable method for synthesizing vinyl anions.
- Lithium-based reagents are commonly used but can require specific conditions.
Purpose of the Study:
- To develop a novel magnesium-mediated Shapiro reaction.
- To explore the use of bismesitylmagnesium as a base for this transformation.
- To evaluate the efficiency and scope of the new protocol.
Main Methods:
- Subjecting various tosylhydrazones to bismesitylmagnesium.
- Introducing electrophiles to the reaction system.
- Optimizing reaction conditions, including temperature and base equivalents.
Main Results:
- Successful mediation of the Shapiro reaction using bismesitylmagnesium.
- High incorporation of electrophiles and good yields of functionalized styrenes.
- Efficient synthesis of aryl enones using Weinreb amides (1.05 equiv).
Conclusions:
- Bismesitylmagnesium is an effective reagent for the Shapiro reaction.
- The developed protocol offers a milder and efficient alternative to lithium-mediated processes.
- This method provides a versatile route to functionalized styrenes and aryl enones.
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