Transfer of Amido Groups from Isolated Rhodium(I) Amides to Alkenes and Vinylarenes

The reaction of monomeric and dimeric rhodium(I) amido complexes with unactivated olefins to
generate imines is reported. Transamination of {(PEt3)2RhN(SiMePh2)2} (1a) or its −N(SiMe3)2 analogue
1b with p-toluidine gave the dimeric [(PEt3)2Rh(μ-NHAr)]2 (Ar = p-tolyl) (2a) in 80% isolated yield. Reaction
of 2a with PEt3 generated the monomeric (PEt3)3Rh(NHAr) (Ar = p-tolyl) (3a). PEt3-ligated arylamides 2a
and 3a reacted with styrene to transfer the amido group to the olefin and to form the ketimine Ph(Me)CN(p-tol) (4a) in 48−95% yields. The dinuclear amido hydride (PEt3)4Rh2(μ-NHAr)(μ-H) (Ar = p-tolyl)
(5a) was formed from reaction of 2a in 95% yield, and a mixture of this dimeric species and the (PEt3)nRhH
complexes with n = 3 and 4 was formed from reaction of 3a in a combined 75% yield. Propene reacted
with 2a to give Me2CN(p-tol) (4b) and 5a in 90 and 57% yields. Propene also reacted with 3a to give 4b
and 5a in 65 and 94% yields. Analogues of 2a and 3a with varied electronic properties also reacted with
styrene to form the corresponding imines, and moderately faster rates were observed for reactions of
electron-rich arylamides. Kinetic studies of the reaction of 3a with styrene were most consistent with formation
of the imine by migratory insertion of olefin into the rhodium-amide bond to generate an aminoalkyl
intermediate that undergoes β-hydrogen elimination to generate a rhodium hydride and an enamine that
tautomerizes to the imine.