Palladium-Assisted Formation of Carbon−Carbon Bonds. 6.¹ Study of the Reactivity of (o-Formylaryl)- or (o-Acetylaryl)palladium Complexes with Alkynes. Synthesis of Indenones and Indenols

Abstract

The reaction of (PhCH2PPh3)2[Pd(R1)Cl(μ-Cl)]2 (1; R1 = 6-formyl-2,3,4-trimethoxyphenyl) with PhC⋮CPh gives a 6.5:1 mixture of 4,5,6-trimethoxy-2,3-diphenylindenone (2)and 4,5,6-trimethoxy-2,3-diphenyl-1H-indenol (3). When the same reaction is carried out with MeO2CC⋮CCO2Me or with Me3SiC⋮CSiMe3, the compounds 4,5,6-trimethoxy-2,3-bis(methoxycarbonyl)indenone (4) and R1C⋮CSiMe3 (5) are obtained, respectively. The reactions of PhC⋮CPh with [Pd(R1)Cl(bpy)] (6; bpy = 2,2‘-bipyridine), in the presence of AgClO4, or with [Pd(R1)(MeCN)(bpy)]ClO4 (7) yield 3 and [Pd(μ-OH)(bpy)]2(ClO4)2 (8a). If 7 reacts with PhC⋮CPh under anhydrous conditions, the indenone 2 is obtained. The complex [Pd(R2)(MeCN)(bpy)]ClO4 (9; R2 = 2-formyl-3,4,5-trimethoxyphenyl) reacts with PhC⋮CPh, giving 5,6,7-trimethoxy-2,3-diphenyl-1H-indenol (10) or, under anhydrous conditions, 5,6,7-trimethoxy-2,3-diphenylindenone (11). A 1:1 mixture of both compounds is obtained by reacting [Pd(η2-R2)(μ-Cl)]2 (12) with PhC⋮CPh. [Pd(η2-R3)(bpy)](CF3SO3) (13; R3 = 6-acetyl-2,3,4-trimethoxyphenyl) reacts with the alkynes RC⋮CR‘ (R = R‘ = Ph, 4-tolyl, CO2Me, Me, Et; R = Ph, R‘ = CO2Et, 4-nitrophenyl, 4-methoxyphenyl, Me; R = tBu, R‘ = H, Me), yielding [Pd(μ-OH)(bpy)]2(CF3SO3)2 (8b) and 1-methylindenols 14−24. The catalytic reaction of [Hg(R1)2] with PhC⋮CPh and CuCl2 in the presence of Q2[Pd2Cl6] (1:6:2:0.05; Q = Me4N, PhCH2PPh3) gives the indenol 3 in 62% yield with respect to the group R present in the mercurial compound. When a similar reaction (Q = PhCH2PPh3) is carried out under nitrogen, the spirocyclic compound 10-formyl-6,7-dimethoxy-1,2,3,4-tetraphenylspiro[4.5]1,3,6,9-decatetraen-8-one (26) is obtained.

Cyclometallation of phenylhydrazones: Synthesis, reactivity, crystal structure analysis and novel trinuclear palladium(II) cyclometallated compounds with [C,N,N′] terdentate ligands

“…The angles between adjacent atoms in the coordination sphere of palladium are close to the expected value of 90°with the most noticeable distortions corresponding to the N(2)-Pd(1)-N(3) angle of 78.85 (8) is longer than Pd(1)-N(2) distance, showing the stronger trans influence of the C(1) carbon atom as compared to the Cl(1) chlorine. The Pd(1)-C(1) bond distance of 1.980(3) Å is somewhat shorter than the value predicted from their covalent radii [31] but similar to values found earlier [21,23,[28][29][30].…”

Synthesis and Reactivity of Ortho-Mercuriated and Ortho-Palladated Arylacetals and Cyclic and Acyclic Aryldithioacetals. New Examples of the Rearrangement of Acyclic Dithioacetal Aryl- to Dithioether Alkyl-Palladium Complexes

“…22 We have reported the synthesis of ortho-palladated complexes by transmetalation reactions, using arylmercurials, by oxidative additions of the corresponding haloarenes to palladium(0) species, or through orthopalladation processes. The first method has allowed us to prepare aryl-palladium complexes bearing CHO, [23][24][25] etamidic acids, 39 and with CO to give aroyl-palladium complexes, [28][29][30][31]37, 39 3-methylenephthalides and 3-ethoxy-3-methyl-3H-isobenzofuran-1-one 39 or, in the presence of O 2 , palladium benzoate complexes. 28,29 We have reported that certain 2,3,4-trimethoxy-6-formylphenylpalladium complexes undergo a rare rearrangement, involving a positional change between the formyl group and the palladium moiety with breaking and reforming of C-C and C-Pd bonds, to give the corresponding 3,4,5-trimethoxy-2-formylphenylpalladium isomers (Chart 1).…”

Cyclometallated complexes derived from pyrimidin- and pyridazinehydrazones: Structural evidence of intermolecular “chelate metal ring” π–π interactions

“…32,47,56,57]. The Pd-N(3) bond length shows the greater trans influence of the C(1) carbon as compared to the P(1) phosphorus.The coordination sphere around palladium [Pd(1), C(1), N(2), N(3), P(1)] is planar (r.m.s.…”