Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocycles
The complexes resulting from the 1:4 mixture of [Pd2(dba)3] and P(o-tolyl)3 in benzene react with ortho substituted-arylbromides to generate in situ the corresponding bromide dimer [Pd(Ar)(m-Br){P(o-tolyl)3)}] 2. Addition of 2 equiv. of (S)-BINAP gave the corresponding [PdBr(o-RC6H4){(S)-BINAP}] in...
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| Format: | Article |
| Language: | English |
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Sociedade Brasileira de Química
2004-01-01
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| Series: | Journal of the Brazilian Chemical Society |
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| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532004000100014 |
| _version_ | 1819210942730207232 |
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| author | Monteiro Adriano L Davis William M |
| author_facet | Monteiro Adriano L Davis William M |
| author_sort | Monteiro Adriano L |
| collection | DOAJ |
| description | The complexes resulting from the 1:4 mixture of [Pd2(dba)3] and P(o-tolyl)3 in benzene react with ortho substituted-arylbromides to generate in situ the corresponding bromide dimer [Pd(Ar)(m-Br){P(o-tolyl)3)}] 2. Addition of 2 equiv. of (S)-BINAP gave the corresponding [PdBr(o-RC6H4){(S)-BINAP}] in good yields (57-89%). The crystal structure of [PdBr(o-C6H4CH2 CON(H)Bn){(S)-BINAP}] (1) shows a square planar arrangement around palladium with the aryl ring positioned nearly perpendicular to the square-planar coordination plane. Since these complexes exhibit restricted rotation about the palladium-aryl bond and contain a chiral ligand, they exist as two distinct diastereoisomers discernable by 31P{¹H} NMR. The dynamic behavior of the complexes 1, 13CO-1, and 15N-1 in CDCl3 was studied by 31P{¹H} NMR spectroscopy. 13CO-labeled 1 was also studied by 13C{¹H} NMR. At temperatures below 0 ºC three species were detected on the 31P{¹H} and 13C{¹H} NMR time scale. They were assigned as the two diastereoisomers and the cationic complex [Pd(o-C6H4CH2 CON(H)Bn) {(S)-BINAP}]+Br. Above 40ºC only the two diastereoisomers were detectable. At higher temperatures rotation increased and at 80 ºC a coalescence of the signals was observed by 13C{¹H} NMR. However, no interconversion was observed for 1 in tol-d8 in the -35-120 ºC range on the NMR time scale. In addition, the existence of the interconversion between the two isomers was directly demonstrated by an inversion transfer 31P NMR experiment. The cyclopalladated complexes [Pd(o-C6H4CH2 CONBn)L2] [11 L2= DPPF, 68% yield; 12 L2 = (S)-BINAP, 88 yield] were obtained by treatment of the aryl bromide complexes with NaO-t-Pn. 31P{¹H} NMR spectra of the 15N labeled complexes 11 and 12 clearly showed a Pd-N bond. Decomposition of the palladacycle 12 afforded the heterocycle and the amide reduced product. |
| first_indexed | 2024-12-23T06:19:12Z |
| format | Article |
| id | doaj.art-47dfb3916b4a43dab1e2a619992d70cc |
| institution | Directory Open Access Journal |
| issn | 0103-5053 |
| language | English |
| last_indexed | 2024-12-23T06:19:12Z |
| publishDate | 2004-01-01 |
| publisher | Sociedade Brasileira de Química |
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| series | Journal of the Brazilian Chemical Society |
| spelling | doaj.art-47dfb3916b4a43dab1e2a619992d70cc2022-12-21T17:57:14ZengSociedade Brasileira de QuímicaJournal of the Brazilian Chemical Society0103-50532004-01-011518395Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocyclesMonteiro Adriano LDavis William MThe complexes resulting from the 1:4 mixture of [Pd2(dba)3] and P(o-tolyl)3 in benzene react with ortho substituted-arylbromides to generate in situ the corresponding bromide dimer [Pd(Ar)(m-Br){P(o-tolyl)3)}] 2. Addition of 2 equiv. of (S)-BINAP gave the corresponding [PdBr(o-RC6H4){(S)-BINAP}] in good yields (57-89%). The crystal structure of [PdBr(o-C6H4CH2 CON(H)Bn){(S)-BINAP}] (1) shows a square planar arrangement around palladium with the aryl ring positioned nearly perpendicular to the square-planar coordination plane. Since these complexes exhibit restricted rotation about the palladium-aryl bond and contain a chiral ligand, they exist as two distinct diastereoisomers discernable by 31P{¹H} NMR. The dynamic behavior of the complexes 1, 13CO-1, and 15N-1 in CDCl3 was studied by 31P{¹H} NMR spectroscopy. 13CO-labeled 1 was also studied by 13C{¹H} NMR. At temperatures below 0 ºC three species were detected on the 31P{¹H} and 13C{¹H} NMR time scale. They were assigned as the two diastereoisomers and the cationic complex [Pd(o-C6H4CH2 CON(H)Bn) {(S)-BINAP}]+Br. Above 40ºC only the two diastereoisomers were detectable. At higher temperatures rotation increased and at 80 ºC a coalescence of the signals was observed by 13C{¹H} NMR. However, no interconversion was observed for 1 in tol-d8 in the -35-120 ºC range on the NMR time scale. In addition, the existence of the interconversion between the two isomers was directly demonstrated by an inversion transfer 31P NMR experiment. The cyclopalladated complexes [Pd(o-C6H4CH2 CONBn)L2] [11 L2= DPPF, 68% yield; 12 L2 = (S)-BINAP, 88 yield] were obtained by treatment of the aryl bromide complexes with NaO-t-Pn. 31P{¹H} NMR spectra of the 15N labeled complexes 11 and 12 clearly showed a Pd-N bond. Decomposition of the palladacycle 12 afforded the heterocycle and the amide reduced product.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532004000100014palladiumpalladacyclesamidationheterocyclesrestricted rotation |
| spellingShingle | Monteiro Adriano L Davis William M Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocycles Journal of the Brazilian Chemical Society palladium palladacycles amidation heterocycles restricted rotation |
| title | Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocycles |
| title_full | Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocycles |
| title_fullStr | Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocycles |
| title_full_unstemmed | Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocycles |
| title_short | Synthesis and characterization in solution and in the solid State of the palladium aryl bromide complexes [Pd(Ar)Br{(S)-BINAP}]: formation of cyclopalladated complexes and direct observation of a C-N reductive elimination to form heterocycles |
| title_sort | synthesis and characterization in solution and in the solid state of the palladium aryl bromide complexes pd ar br s binap formation of cyclopalladated complexes and direct observation of a c n reductive elimination to form heterocycles |
| topic | palladium palladacycles amidation heterocycles restricted rotation |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532004000100014 |
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