Atroposelective synthesis of axially chiral P,S-ligands based on arynes

Abstract

The first atropo-selective aryl-aryl coupling based on arynes in the presence of a tert-butylsulfinyl group as the chiral auxiliary on the aryllithium nucleophile is described. The approach allows for the efficient access to a novel family of atropo-enantiopure biphenyl-based phosphine-thioether ligands. The new P,S heterodonor ligands were assessed in model palladium-catalyzed allylic substitution reactions.

Transition‐Metal‐Free Heterobiaryl Synthesis via Aryne Coupling

“…Especially, the iodinated analog 1b afforded the expected product 5b in a very good 75 % yield and proved to be the best partner of the series. Interestingly, the serious increase of the yield observed when replacing a bromine atom by an iodine one have already been described in the biphenyl series and could be explained by the much faster iodine/lithium exchange occurring with this atom as compared to that with the bromine one …”

“…Interestingly, the serious increase of the yield observed when replacing a bromine atom by an iodine one have already been described in the biphenyl series and could be explained by the much faster iodine/lithium exchange occurring with this atom as compared to that with the bromine one. [38][39][40] Nevertheless, the result obtained with 1d was not as high as we could have imagined especially when considering the impressive enhancement furnished by the related brominated analog 1c. Finally, it has to be noted that either LiBr or LiOTf released during the aryne formation did not affect the reaction, although the effect of this salt remains delicate to comment because it is accumulated all along the coupling step.…”

“…In this context, Leroux et al reported an efficient transition metal free aryl‐aryl coupling protocol, the so‐called “Aryne coupling” reaction . Very recently, we extended the reaction to the construction of hetaryl‐aryl backbones, developing thus the “(Het)‐Aryne” version of the reaction (Scheme ) .…”

“…In this context, Leroux et al reported an efficient transition metal free aryl-aryl coupling protocol, the so-called "Aryne coupling" reaction. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] Very recently, we extended the reaction to the construction of hetaryl-aryl backbones, developing thus the "(Het)-Aryne" version of the reaction (Scheme 1). [44] However, our study essentially focused on the thiophene ring as a model partner.…”

Modular Synthesis of Biaryl‐Substituted Phosphine Ligands: Application in Microwave‐Assisted Palladium‐Catalyzed C–N Cross‐Coupling Reactions

“…We could show that highly regioselective [53,56,57,51,55] halogen–metal interconversions allow for subsequent functionalization. More recently, an atropo‐diastereoselective version and access to enantioenriched biphenyls has been documented 58,59…”