C–H Activation in Primary 3‑Phenylpropylamines: Synthesis of Seven-Membered Palladacycles through Orthometalation. Stoichiometric Preparation of Benzazepinones and Catalytic Synthesis of Ureas

The dimeric cyclometalated complexes
[Pd2{κ2C,N-C6H4­CH2CH2C­(R)­(Me)­NH2-2}2­(μ-Cl)2] (R = Me (1a), H (1b)) are prepared by reacting 1,1-dimethyl-3-phenylpropyl­ammonium
or 1-methyl-3-phenylpropyl­ammonium triflate with Pd­(OAc)2 in a 1:1 molar ratio and subsequent treatment with excess
NaCl. The mononuclear derivatives [Pd­{κ2C,N-C6H4­CH2CH2C­(R)­(Me)­NH2-2}­Cl­(L)] (L = PPh3, R = Me (3a), H (3b); L = 4-picoline
(4-pic), R = Me (4a), H (4b)) were prepared
from 1a,b by splitting the chloro bridges
with the neutral ligands L. A conformational analysis of the mononuclear
palladacycles in solution has been carried out. Insertion of CO takes
place into the Pd–C bond of complexes 1a,b, affording Pd(0) and the tetrahydro-benzazepinone 5a or 5b, which possesses potential pharmacological
interest. Additionally, the triflate salt A or B undergoes catalytic carbonylation with CO to afford the
corresponding N,N′-dialkylurea,
using Pd­(OAc)2/Cu­(OAc)2, in boiling acetonitrile.
The crystal structures of 3a·1/2H2O, 3b, 4b·CHCl3, and 5a were determined by X-ray diffraction studies.