Accessing para-Alkylphenols via Iridium-Catalyzed Site-Specific Deoxygenation of Alcohols

An iridium-catalyzed and phenol-directed deoxygenationof benzylicalcohols comes as an alternative access to 4-alkylphenols, featuringlow catalyst loading (S/C up to20,000, TOF up to 12,400 h(-1)), high functionalitycompatibility, and excellent site-selectivity. The applications inlate-stage modification of steroids and gram-scale total synthesisof a Gastrodia elata extract are highlighted.Mechanistically, the intermediacy of quinone methide controls thesite-selectivity, and the formation of iridium hydride serves as therate-limiting step.

Automated summary

An iridium-catalyzed and phenol-directed deoxygenation method is described for the synthesis of 4-alkylphenols, which offers low catalyst loading, high functionality compatibility, and excellent site-selectivity. The applications in late-stage modification of steroids and gram-scale total synthesis of a Gastrodia elata extract are also highlighted. Mechanistically, the interemediacy of quinone methide controls the site-selectivity, and the formation of iridium hydride serves as the rate-limiting step.