Reinvestigation of the noncatalyzed coupling of aryllithium with haloarene: a novel aromatic nucleophilic substitution pathway.
Noncatalyzed coupling reactions of aryllithiums and haloarenes proceed not only through the well-known aryne route but also, in some cases, through a novel addition-elimination pathway. Indeed, ortho-chloro- and ortho-bromomethoxyarenes lead selectively to the corresponding ortho-biaryls through a chelation-driven aromatic nucleophilic substitution pathway. Contrary to common belief, such noncatalyzed coupling reactions often proceed with high regioselectivity and high yield. These results underline the potency of such simple reactions and open up a straightforward access to a wide range of biaryl structures; this also appears particularly useful for large-scale and biaryl building-block syntheses, as only cheap and readily available substrates are involved.
Becht
Jean-Michel
JM
Laboratoire de Synthèse Bioorganique, UMR 7514 associée au CNRS, Faculté de Pharmacie, 74 Route du Rhin, 67400 Illkirch, France.
Gissot
Arnaud
A
Wagner
Alain
A
Mioskowski
Charles
C