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Regioselective synthesis of 4-hydroxybiphenyl-2-carboxylates via the base-mediated oxygenative [3 + 3] benzannulation reaction of α,β-unsaturated aldehydes and γ-phosphonyl crotonates is reported. A hydroxyl group is installed in the final product on the originally phosphorus-bound carbon via a novel oxygenative and dehydrogenative transformation. The reaction proceeds rapidly in an open flask, uses atmospheric oxygen as an oxidant, and affords good yields of substituted biaryl phenols.

The base-mediated reaction of α,β-unsaturated carbonyl compounds and γ-phosphonylcrotonates under an argon atmosphere readily furnishes substituted cyclohexa-1,3-dienes. The cyclisation proceeds with complete regioselectivity to afford products that are readily amenable to further redox manipulations. The presented method allows the rapid and regioselective syntheses of six-membered carbocycles at three different oxidation levels.

Regioselective synthesis of 4-hydroxybiphenyl-2-carboxylates via the base-mediated oxygenative [3 + 3] benzannulation reaction of α,β-unsaturated aldehydes and γ-phosphonyl crotonates is reported. A hydroxyl group is installed in the final product on the originally phosphorus-bound carbon via a novel oxygenative and dehydrogenative transformation. The reaction proceeds rapidly in an open flask, uses atmospheric oxygen as an oxidant, and affords good yields of substituted biaryl phenols.

According to the title reaction, 4-sulfonylcrotonates or 1,3-bissulfonylpropene are transformed with α,β-unsaturated aryl aldehydes, citronellal, or ketones to form highly substituted 3-sulfonyl benzoic ester derivatives.

Facile conversion of α,β-unsaturated aldehydes and ketones into highly substituted arenes via a base-mediated, completely regioselective, air-oxidative [3 + 3] benzannulation reaction with readily available 4-sulfonylcrotonates or 1,3-bisphenylsulfonylpropene is reported. The reaction can also be carried out as a one-pot, three-component operation using 4-bromocrotonates, aryl sulfinates, and cinnamaldehyde. This open-flask, metal-free reaction does not require anhydrous solvents, proceeds under mild conditions, and uses atmospheric oxygen as the oxidant to afford high yields of the 3-(arylsulfonyl)benzoic acid esters.