Aryl‐Copper(III)‐Acetylides as Key Intermediates in C sp 2Csp Model Couplings under Mild Conditions. Issue 32 (10th July 2014)

• Record Type: Journal Article
• Authors: Rovira, Mireia; Font, Marc; Acuña‐Parés, Ferran; Parella, Teodor; Luis, Josep M.; Lloret‐Fillol, Julio; Ribas, Xavi
• Is Part Of: Chemistry. Volume 20:Issue 32(2014)
• Page Start: 10005
• Page End: 10010
• Publication Date: 2014-07-10
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201402711
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The mechanism of copper‐mediated Sonogashira couplings (so‐called Stephens–Castro and Miura couplings) is not well understood and lacks clear comprehension. In this work, the reactivity of a well‐defined aryl‐Cu<sup>III</sup> species (<bold>1</bold><inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pghwhbv7kg" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09476539:media:CHEM201402711:tex2gif-inf-3" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>ClO</mml:mtext><mml:msub><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>4</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:msub></mml:math></alternatives></inline-formula>) with <italic>p</italic>‐R‐phenylacetylenes (R=NO<sub>2</sub>, CF<sub>3</sub>, H) is reported and it is found that facile reductive elimination from a putative aryl‐Cu<sup>III</sup>‐acetylide species occurs at room temperature to afford the C<sub>aryl</sub>C<sub>sp</sub> coupling species (<bold>I<sub>R</sub></bold>), which in turn undergo an intramolecular reorganisation to afford final heterocyclic products containing 2<italic>H</italic>‐isoindole (<bold>P</bold><inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pghwhbvjqw" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09476539:media:CHEM201402711:tex2gif-inf-10" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>NO</mml:mtext><mml:msub><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>2</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:msub></mml:math></alternatives></inline-formula>, <bold>P</bold><inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pghwhbvjmb" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09476539:media:CHEM201402711:tex2gif-inf-12" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>CF</mml:mtext><mml:msub><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>3</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:msub></mml:math></alternatives></inline-formula>, <bold>P<sub>Ha</sub></bold>) or 1, 2‐dihydroisoquinoline (<bold>P<sub>Hb</sub></bold>) substructures. Density Functional Theory (DFT) studies support the postulated reductive elimination pathway that leads to the formation of C<inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pghwhbvjj9" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09476539:media:CHEM201402711:tex2gif-inf-16" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>sp</mml:mtext><mml:msup><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>2</mml:mtext></mml:mrow></mml:msup></mml:mrow></mml:msub></mml:math></alternatives></inline-formula>C<sub>sp</sub> bonds and provide the clue to understand the divergent intramolecular reorganisation when <italic>p</italic>‐H‐phenylacetylene is used. Mechanistic insights and the very mild experimental conditions to effect C<sub>aryl</sub>C<sub>sp</sub> coupling in these model systems provide important insights for developing milder copper‐catalysed C<sub>aryl</sub>C<sub>sp</sub> coupling reactions with standard substrates in the future.</p> </abstract>