What is it about?
This study presents an efficient three-step synthesis of tert-butyl cyclopropanecarboxylates from 1-chlorovinyl p-tolyl sulfoxides. Lithium ester enolates first undergo conjugate addition to the sulfoxides, followed by removal of the sulfinyl group through a sulfoxide–magnesium exchange reaction. Finally, base-promoted cyclization forms the cyclopropane ring in high yield. The method is applicable to a broad range of substrates and can also produce optically active cyclopropanecarboxylates with excellent enantiomeric excesses.
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Why is it important?
Cyclopropanecarboxylates are valuable building blocks for the synthesis of natural products, pharmaceuticals, and other biologically active compounds. This work provides a practical and highly efficient alternative to conventional cyclopropane-forming methods by combining conjugate addition, sulfoxide–magnesium exchange, and intramolecular cyclization in a simple sequence. The strategy also enables the preparation of optically active cyclopropane derivatives, making it useful for asymmetric synthesis.
Perspectives
This work demonstrates that 1-chlorovinyl p-tolyl sulfoxides can act as versatile synthetic platforms. After conjugate addition, removal of the sulfinyl group reverses the polarity of the carbon atom, enabling intramolecular cyclization to form cyclopropane rings. We look forward to discovering further transformations that take advantage of this unique reactivity of 1-chlorovinyl p-tolyl sulfoxides.
Associate Professor Tsutomu Kimura
Read the Original
This page is a summary of: Efficient Synthesis of Cyclopropanecarboxylic Acid Esters Starting from the Conjugate Addition of Lithium Ester Enolates to 1-Chlorovinyl p-Tolyl Sulfoxides, Synlett, January 2013, Thieme Publishing Group,
DOI: 10.1055/s-0032-1318168.
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