Reactivity of ortho-β-Enaminone-phenyl Palladium Complexes. Insertion of CO into the Pd-C Bond to Give the First Acyl C,N,O-Pincer Complexes. Sequential Insertion of Dimethylacetylenedicarboxylate into the Enaminone C-H Bond and of Isocyanide into the Pd-C Bond. A New Photooxigenation/Cyclization Process

Insertion of CO into the Pd-C-aryl bond of complexes [PdI{C6H4{NHC(Me)CHC(O)Me}-2}-((NN)-N-boolean AND)] afforded the benzoyl derivatives [Pdl{C(O)C6H4{NHC(Me)CHC(O)Me}-2}((NN)-N-boolean AND)] [(NN)-N-boolean AND = 4,4'-di-tert-butyl-2,2'-dipyridyl ((t)Bubpy) (1a), N,N,N',N'-tetramethylethylenediamine (tmeda) (1b)]. The reactions of [Pd{C,C-C6H4{NH=C(Me)CHC(O)Me}-2}(tmeda)]OTf (OTf = CF3SO3) with excess CO and tmeda (2:1) or HOTf (1:1) produced the dinuclear benzoyl complex [{Pd{C,N, O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}(2)(mu-tmeda)] (2) or [Pd-2{mu-O,C,N,O'-{O=CC6H4{NC(Me)CHC(O)Me}-2}(2)}] (3). respectively. The latter reacted with anionic or neutral ligands to give complexes Bu4N[{Pd{C,N,O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}(2)(mu-OH)] (4), Q[Pd{C,N,O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}}Cl [Q = PPN (5a), NMe4 (5b)], or [{Pd{C,N,O-{C(O)C6H4{NC(Me)CHC(O)Me}-2}L] (L = (CNBu)-Bu-t (6a), CNXy (6b), PPh3 (6c), NH3 (6d), NH2Me (6e), MeCN (6f), dmso (6g)), respectively. The reaction of dimethylacetylenedicarboxylate (DMAD) with [PdI{C6H4{NHC(Me)CHC(O)Me}-2}(tmeda)] (1:1) afforded [PdI{C6H4{NHC(Me)C{Z-C(CO2Me)=CH(CO2Me)}C(O)Me}}-2}(tmeda)] (7Z), resulting from the insertion of the alkyne into the C-(sp(2))-H bond of the enaminone substituent. 7Z isomerized into the E analogue (7E) when heated in toluene at 95 degrees C and reacted in two steps with AgClO4 and XyNC (1:1:2) to give the C,N,O-pincer derivative Pd{C,N,O-{C(=NXy)C6H4{NC(Me)C{C(CO2Me)=CHCO2Me)}C(O)Me}-2}(CNXy)] (8) as a mixture of the Z and E isomers. The latter complex converted, after a photochemical oxygenation, into the palladacycle [Pd{C,N,O-{C(=NXy)C6H4{N(dmoc)}-2](CNXy)]center dot 2CHCl(3) (9), where the imino substituent dmoc is the cycle 1,2-di(methoxycarbonyl)-3-oxocyclopent-1-ene-4-yl. Compound 8 or 9 reacted with trillic or picric acid to give the species Pd{C,N,O-{C(=NHXy)C6H4{NC(Me)C{C(CO2Me)=CHCO2Me)}C(O)Me}-2}(CNXy)]OTf (10) or [Pd{C,N,O-{C(=NXy)C6H4{N(dmoc)}-2](CNXy)center dot[Hpic (11; hpic = picric acid), respectively. The crystal structures of complexes 2, 3, 5a, 6b, 6c, 6e, 7Z, 7E, and 10 have been determined.