Reactions of Cyclopalladated Benzylidene‐aniline Schiff's Base Complexes. Selective Synthesis of 2′‐Substituted Schiff's Base Derivatives and the X‐Ray Crystal Structure of the Dimer [Pd(μ‐OAc)(5′‐OCH₃C₆H₃CHNC₆H₄‐4‐CH₃)]₂

Abstract

The 2′‐cyclopalladated imine complex , reacts with CO in MeOH to afford the 2′‐substituted aryl imine 2′‐CO2CH3‐5′‐OCH3C6H3CHNTol (Tol = C6H4‐4‐CH3). The product of this reaction can be altered by changing the bridging ligand from AcO to Cl, in which case only the 5‐membered ring heterocyclic compound is obtained. [Pd(μ‐OAc)(1a)]2 with 2 equiv. of Ph3P and CO (1 atm) gives the heterocyclic which arises from two CO insertion reactions, whereas [PdX(1a)]2 (X = AcO, Cl) with 4 equiv. of CNBut and 4 equiv. of Ph2PCH2CH2PPh2 affords the heterocyclic ketenimine [PdCl(1a)]2 reacts with CH2CHCO2CH2CH3 to afford 2′(CHCHCO2CH2CH3)‐5′‐OCH3C6H3CHO, and [Pd(μ‐OAc)(1a)]2 with I2 to give 2′‐I‐5′‐OCH3C6H3CHO. Excess CH3O2CCCCO2CH3 reacts with various substituted cyclopalladated Schiff's bases in MeOH to afford which we formulate as possessing two PdC bonds, and one coordinated ester O atom. The X‐ray crystal structure of [Pd(μ‐OAc)(1a)]2 has been determined; relevant bond lengths [Å] and bond angles [°] are: PdO(1), 2.139(6), PdO(2), 2.026(6), PdN, 2.039(6), PdC(2′), 1.951(8), PdPd, 3.113(1), NPdC(2′), 80.9(3), NPdO(1), 97.5(2), C(2′)PdO(2), 91.7(3), O(1)PdO(2), 89.2(2).

Synthesis and reactivity towards carbon monoxide of an optically active endo five-membered ortho-cyclopalladated imine: X-ray molecular structure of trans-(μ-Cl)2[Pd(κ2-C,N-(R)-C6H4-CHN-CHMe-Ph)]2

“…Finally, it should be noted that the selectivity change in the carbonylation products of compounds 2 and 3, when the acetato ligands are replaced by chloro ligands in the starting endo five-membered ortho-cyclopalladated imine, is remarkable and reproduces well the results previously reported [17][18][19]59]. …”

“…Scheme 2 shows the mechanism proposed for the carbonylation reaction of endo five-membered ortho-cyclopalladated imines in methanol, leading to methyl 2-formylbenzoates or 3-methoxy-2-(aryl or benzyl)isoindolin-1-ones, including the compounds prepared in this work by the carbonylation reaction of compounds 2 and 3 [18]. Compounds 2 and 3 were treated in methanol at room temperature with carbon monoxide at 1.6 bar in a glassware reactor for 6 and 24 h, respectively (Scheme 1).…”

“…1), with the aim of obtaining this type of compound in a diastereoselective form [17][18][19]. For this purpose, we prepared the optically active endo five-membered orthocyclopalladated imines 2 and 3 (Scheme 1) and studied their reactivity towards carbon monoxide in methanol.…”

Cyclometallated Pd(ii) azido complexes containing 6-phenyl-2,2′-bipyridyl or 2-phenylpyridyl derivatives: synthesis and reactivity toward organic isocyanides and isothiocyanates

“…Although many studies on the isocyanide insertion for organopalladium aryl complexes to form palladium imidoyl compounds have been reported, the insertion of isocyanide into the palladium aryl compounds containing pseudo-halogen ligands has not been reported. 17,[24][25][26][27][28][29][30][31][32][33][34] IR spectra of imidoyl Pd(II) azido complexes 23-27 show a stretch band at 2031-2038 cm −1 due to the m(N 3 ), which is slightly shifted to lower values compared to that (2040-2051 cm −1 ) of starting materials. Interestingly, 1 H NMR spectra of each methyl group (-CH(CH 3 ) 2 ) in the 2,6-diisopropylarylimidoyl group of complexes 23-26 display four doublets coupled with the proton of the isopropyl group (-CH(CH 3 ) 2 ), which indicate the magnetically inequivalent methyl groups in solution.…”

Cyclometallated complexes promoted asymmetric insertion and hydrophosphination reactions

“…Insertion reactions of isocyanides into Pd-C bonds are involved in the synthesis of aminoisoindolinium salts, 123,124 3-imino-2-phenylindazolines, 125 2-cyano-1-arylazonaphthalenes, 3-amino-2-arylbenzoindazoles, 126 ketenimines, 127,128 2,3-dihydroisoindol-1-ones, 129 and 20 other N-heterocycles, 130 or N-functionalized arenes. 129,131 The insertion reactions of isocyanides into the aryl-palladium bond to give iminoacyl complexes are well-known.…”