Rearrangement of biaryl monoaminocarbenes via concerted asynchronous insertion into aromatic C-H bonds

The biphenyl and binaphthyl diisopropylaminocarbenes were found to be only transient species that spontaneously and quantitatively rearrange into the corresponding aminofluorenes. DFT calculations confirm that these insertion reactions of aminocarbenes into proximal aromatic C-H bonds require only a moderate energy barrier and support a concerted, strongly asynchronous, mechanism dominated by C-arom-C-carbene proton transfer.