Oxygenative and Dehydrogenative [3 + 3] Benzannulation Reactions of α,β-Unsaturated Aldehydes and γ‑Phosphonyl Crotonates Mediated by Air: Regioselective Synthesis of 4‑Hydroxybiaryl-2-carboxylates

• Published in: Organic letters Vol. 18; no. 4; pp. 752 - 755
• Main Authors: Joshi, Prabhakar Ramchandra, Nanubolu, Jagadeesh Babu, Menon, Rajeev S
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19-02-2016
• Subjects: Aldehydes - chemistry; Carboxylic Acids - chemical synthesis; Carboxylic Acids - chemistry; Catalysis; Crotonates - chemistry; Molecular Structure; Phenols - chemical synthesis; Phenols - chemistry; Stereoisomerism
• ISSN: 1523-7060; 1523-7052
• DOI: 10.1021/acs.orglett.6b00016

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.