Regio- and chemoselective direct generation of functionalized aromatic aluminum compounds using aluminum ate base

Abstract

A regio- and chemoselective direct method for generation of functionalized aromatic aluminum compounds through deprotonative directed ortho-alumination using triisobutyl(tetramethylpiperidino)aluminate (iBu3Al(TMP)Li), prepared by mixing of triisobutylaluminum (iBu3Al) and lithium tetramethylpiperidide (LTMP) in THF, has been developed. Deprotonative alumination of various functionalized benzenes with the use of iBu3Al(TMP)Li proved effective for the direct generation of various ortho-functionalized aluminum aromatic and heteroaromatic derivatives, particularly those with electrophilic functional groups such as cyano, amide, and halogen. Direct alumination, followed by electrophilic trapping (with I2), provided a convenient preparative method for 1,2- or 1,2,3-multisubstituted aromatic compounds. The functionalized aromatic aluminate intermediate also was found to undergo copper- and palladium-catalyzed C-C bond-forming reactions very efficiently and highly regio- and chemoselectively.