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.
Efficient access to dibenzothiophene-S-oxides from differently substituted 2-bromo-diarylsulfinyl moieties using ligandless Pd(OAc)2 as the catalyst and KOAc as the base in dimethylacetamide at 130 °C is reported. Various dibenzothiophene-S-oxides were obtained in excellent yields.
We report the preparation of axially stereoenriched biphenyls by the coupling of in situ generated aryllithiums and arynes using chiral oxazoline auxiliaries. The design of the aryne precursors, the choice of oxazoline and the reaction conditions were key to accessing the desired, highly substituted, atropisomerically enriched biarylic products. In one case, the two atropo‐diastereomers could be obtained in isomerically pure form by column chromatographic separation and their absolute configurations established by X‐ray crystallography. The stereoselectivity of the reaction seems to be governed by subtle parameters.
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