Deamination of the Amino Acid Fragment in Imine Metallacycles: Unexpected Synthesis of an NH‐Aldimine Organometallic Compound

Abstract

We report that the action of Lewis bases, such as triphenylphosphine, pyridine, or trimethylamine, on imine metallacycles derived from amino acids leads to the formation of the first organometallic compound of an NH aldimine, a highly reactive organic species, and the corresponding alpha-ketoester, in a deamination reaction that mimics the metabolism of alpha-amino acids. The synthesis of different cyclopalladated compounds by a reaction between palladium acetate and the Schiff bases 2,4,6-Me(3)C(6)H(2)CH=NCH(R(1))COOR(2) (R(1) = CH(2)Ph, R(2) = Et and R(1) = Ph, R(2) = Me) is also reported.

Cyclopalladated and cycloplatinated benzophenone imines: Antitumor, antibacterial and antioxidant activities, DNA interaction and cathepsin B inhibition

“…In the ESI mass spectrometry, compound 5 produced intense signals for the cations [M − Cl + CH3CN]+ and [M − Cl]+, in accordance with the labile nature of Pt(II)\Cl σ bond and the coordinative nature of themolecules of acetonitrile, which was used as a solvent in this technique [45]. The most interesting features of the 1H NMR spectrum of compound 5 were: i) the lack of the signal due to theH1 proton,which demonstrated its ortho-metallated nature, ii) the chemical shift of its NH proton (9.34 ppm) relative to free benzophenone imine (8.40 ppm), which was consistent with the coordination of the iminic nitrogen to the platinum(II) center, and iii) the chemical shift of the H2-H5 protons of the ortho-platinated phenyl ring in the interval between 7.16 and 6.58 ppm, which was consistent with the trans-N,P configuration of compound 5 [32,[45][46][47][48]. Protons H2-H5 present these low chemical shifts because they are located in the shielding zone of the PPh3 aromatic rings of compound 5 [32,[35][36][37][38].…”

A New Method for High-Yield Cyclopalladation of Primary and Secondary Amines. Atom-Efficient Open-to-Air Inexpensive Synthesis of Buchwald-Type Precatalysts

“…In both complexes, the chelated amino ( 3b-I ·CHCl 3 ) or imino ligand ( 4 ) forms a six-membered metallacycle with a boat conformation. The features of complexes 3b-I ·CHCl 3 and 4 are similar to those of analogous phosphino complexes containing primary ortho-metalated phenethylamines ,, or related imino ligands . The X-ray crystallographic study reveals the S absolute configuration of the α-carbon stereocenter in complex 3b-I ·CHCl 3 .…”

Mono- and Dialkyne Insertion Reactions of Cyclopalladated N,N′,N″-Triarylguanidines [κ2(C,N)Pd(μ-Br)]2 and cis-/trans-[κ2(C,N)Pd(Lewis Base)Br]. Scaffolds for Enlarged, Rearranged, and Zwitterionic Palladacycles through Ring Contraction cum Amine–Imine Tautomerization

“…Cyclopalladated exocyclic imines were shown to exist as a mixture of E and Z isomers in solution due to the CN double-bond rotation, the E / Z ratio being controlled by steric and electronic effects of the R group in the >NC(H)R unit. , The monoalkyne- and dialkyne-inserted palladacycles prepared in the present investigation are unlikely to undergo the CN double-bond rotation of the CN 3 unit in the guanidine moiety due to steric constraints. Thus, only the C–N single-bond rotation of the CN 3 unit in the guanidine moiety of 1 – 7 and 12 – 21 is the likely process operating in solution (see later).…”