Palladium-Catalyzed Cross Coupling Reaction of N-Alkoxyimidoyl Bromides and Its Application to One-Pot Synthesis of N-Arylamines

Abstract

The synthetic utility of N-alkoxyimidoyl halides is demonstrated using the palladium-catalyzed cross-coupling reaction. The Sonogashira and Suzuki-Miyaura coupling reactions of N-alkoxyimidoyl bromides produced versatile ketoxime ethers in good to excellent yields. A one-pot reaction of the imidoyl bromides with arylboronic acid and allylmagnesium bromide to produce N-arylamines via Suzuki-Miyaura coupling followed by domino reaction involving sequential addition-eliminative rearrangement-addition reactions was developed.

Stereospecific Suzuki, Sonogashira, and Negishi Coupling Reactions ofN-Alkoxyimidoyl Iodides and Bromides

“…44−48 Subsequently Miyata et al wrote a communication reporting the Sonogashira and Suzuki coupling of N-alkoxybenzimidoyl bromides. 49 Their report indicated that the Sonogashira coupling generally gave good yields (67−91%) of the coupling product, but the study was somewhat limited in scope. The Suzuki coupling reaction required high catalyst (10 mol %) and ligand (20 mol %) loadings.…”

“…This reaction gave excellent yields and was thought to proceed with retained stereochemistry, but no evidence was given to support this conclusion. Our group provided the first report of Sonogashira and Suzuki coupling reactions of N -alkoxybenzimidoyl iodides [ArC(I)NOR], which demonstrated the ability to target a single geometric isomer of the oxime ether product. − Subsequently Miyata et al wrote a communication reporting the Sonogashira and Suzuki coupling of N -alkoxybenzimidoyl bromides . Their report indicated that the Sonogashira coupling generally gave good yields (67–91%) of the coupling product, but the study was somewhat limited in scope.…”

Metal-Free Transformation of Sulfonyl Oxime Ethers with Amines to Oxime Ethers

“…3 alkoxyimidoyl bromides produced ketoxime ethers has been elegantly developed by Miyata's group (Scheme 1b). 4 An alternative way is the radical-mediated substitutive functionalization of sulfonyl oxime ethers that is appealing due to the easy availability of aryl radical precursors. Nevertheless, pioneering examples to synthesize oxime ethers via radical coupling of phenyl iodide with phenylsulfonyl oxime ether as demonstrated by Kim and co-workers were plagued by the stoichiometric amount of toxicorganotin reagents (Scheme 1c).…”

“…For example, Kim’s group reported that N -alkoxyimidoyl bromides are efficient coupling partners with organotin compounds in the Stille reaction to build oxime ethers (Scheme a) . Subsequently, the palladium-catalyzed Suzuki–Miyaura coupling of N -alkoxyimidoyl bromides produced ketoxime ethers has been elegantly developed by Miyata’s group (Scheme b) . An alternative way is the radical-mediated substitutive functionalization of sulfonyl oxime ethers that is appealing due to the easy availability of aryl radical precursors.…”