Hemilabile Benzyl Ether Enables γ-C(sp3)–H Carbonylation and Olefination of Alcohols
摘要:
Pd-catalyzed C(sp(3))-H activation of alcohol typically shows beta-selectivity due to the required distance between the chelating atom in the attached directing group and the targeted C-H bonds. Herein we report the design of a hemilabile directing group which exploits the chelation of a readily removable benzyl ether moiety to direct gamma- or delta-C-H carbonylation and olefination of alcohols. The utility of this approach is also demonstrated in the late-stage C-H functionalization of beta-estradiol to rapidly prepare desired analogues that required multi-step syntheses with classical methods.