Toward a Catalytic Atroposelective Synthesis of Diaryl Ethers Through C(sp²)–H Alkylation with Nitroalkanes

Published as part of the Cluster Atropisomerism

Abstract

We report studies toward a small-molecule-catalytic approach to access atropisomeric diaryl ethers that proceeds through a C(sp²)–H alkylation using nitroalkanes as the alkyl source. A quaternary ammonium salt derived from quinine, containing a sterically hindered urea at the C-9 position, was found to effect atroposelective C(sp²)–H alkylation with moderate to good enantioselectivities across several naphthoquinone-containing diaryl ethers. Products could then be isolated in >95:5 er after one round of trituration. For several substrates that were evaluated, we obtained nitroethylated products in similar yields and selectivities.

Key words

atropisomerism - alkylation - phase-transfer catalysis - asymmetric catalysis - chirality

• References and Notes

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