Facile access to sterically hindered aryl ketones via carbonylative cross-coupling: application to the total synthesis of luteolin

A general and mild protocol for achieving the carbonylative cross-coupling of sterically hindered, ortho-disubstituted aryl ketones is reported. The commercially available PEPPSI-IPr catalyst is shown to efficiently promote the carbonylative cross-coupling of hindered ortho-disubstituted aryl iodides to give diaryl ketones; traditional phosphine catalysts are less effective. Carbonylative Suzuki-Miyaura cross-couplings provide a diverse array of biaryl ketones in good to excellent yields. The same catalyst is also shown to catalyze a carbonylative Negishi cross-coupling reaction, utilizing a variety of alkynyl-zinc reagents to give the corresponding alkynyl aryl ketones. Application of this new methodology to the synthesis of the natural product luteolin is reported. (C) 2011 Elsevier Ltd. All rights reserved.