N,N-diethyl O-carbamate: Directed metalation group and orthogonal Suzuki-Miyaura cross-coupling partner

Article abstract of DOI:10.1021/ja907700e

(Chemical Equation Presented) The first Suzuki-Miyaura cross-coupling of an aryl O-carbamate, a versatile and powerful directed metalation group (DMG) in directed ortho metalation (DoM) chemistry, is described using the inexpensive, bench-stable catalyst NiCl₂(PCy₃)₂. Broad synthetic scope and good efficiency are demonstrated for aryl and heteroaryl O-carbamates. The role of water and hydrolysis equilibrium between free boronic acid and boroxine was established to be a crucial parameter for this transformation. When combined with DoM and traditional Pd-catalyzed Suzuki-Miyaura strategies, the methodology offers concise routes to uniquely substituted molecules, avoiding the need for protection/deprotection of the phenol and the use of strongly nucleophilic cross-coupling partners.