trans-Chlorido[6-chloro-4-(4-methoxybenzyl)-3-oxo-3,4-dihydropyrazin-2-yl]bis(triphenylphosphine)palladium(II)

Abstract

The title compound, [Pd(C12H10ClN2O2)Cl(C18H15P)2], is the intermediate of the reduction of a 3,5-dichloropyrazinone [Loosen, Tutonda, Khorasani, Compernolle & Hoornaert (1991). Tetrahedron, 47, 9259–9268]. This species is formed by oxidative addition of coordinatively unsaturated Pd0 to the reactive 3-position of the heterocycle. The coordination around the Pd atom is square planar, with two trans PPh3 ligands. π–π interactions are observed between the centroid of the pyrazinone ring and planes of two adjacent phenyl rings, one from each PPh3 group (3.25 and 3.078 Å), stabilizing the intermediate structure. This could explain the reduced reactivity towards substitution of the Cl atom by the formate anion, resulting in poor yield of the reduced compound. 3-Substituted pyrazinones are important precursors in the synthesis of 5-aminopiperidinone-2-carboxylate (APC) systems.