Artigo Revisado por pares

Insertion Reactions on Carbopalladated Benzyne: From Eight- to Nine- and Ten-Membered Palladacycles. Applications to the Synthesis of N-Heterocycles

2014; American Chemical Society; Volume: 33; Issue: 22 Linguagem: Inglês

10.1021/om500772p

ISSN

1520-6041

Autores

María‐José Oliva‐Madrid, José-Antonio Garcı́a-López, Isabel Saura‐Llamas, Delia Bautista, José Vicente,

Tópico(s)

Catalytic Alkyne Reactions

Resumo

The ortho-metalated complexes [Pd{C,N-C6H2CH2CH2NH2-2,(OMe)2-4,5}(μ-Br)]2 (A) and [Pd{C,N-C6H4CH2CMe2NH2-2}(μ-Cl)]2 (B), derived from homoveratrylamine and phentermine, respectively, react with benzyne generated in situ, to afford the previously reported eight-membered palladacycles 1a and 1b, respectively, arising from the insertion of one molecule of the aryne into the Pd–Caryl bond. Complexes 1 react with isocyanides RNC (R = Xy, tBu) in 1:4 molar ratio to give the nine-membered iminoacyl palladacycles [Pd(C,N-C(═NR)-C6H4{C6H2CH2CH2NH2-2(OMe)2-4,5)-2′})Br(CNR)] (R = Xy (2a), R = tBu (3a)) and [Pd(C,N-C(═NXy)-C6H4{C6H4CH2CMe2NH2-2)-2′})Cl(CNR)] (R = Xy (2b), R = tBu (3b)). Complex 2a decomposes in refluxing toluene to afford palladium(0) and 7,8-dihydro-10,11-dimethoxy-5-[(2,6-dimethylphenyl)imino]dibenzo[c,e]azocinium triflate (4a). When 1b reacts with TlOTf and XyNC (molar ratio 1:2:2), 7,8-dihydro-5-[(2,6-dimethylphenyl)imino]-7,7-dimethyldibenzo[c,e]azocinium triflate (4b) is obtained, resulting from an isocyanide insertion/C–N reductive coupling sequence. The amidinium triflates 4a and 4b present E/Z isomerism in CHCl3 solution. The stoichiometric carbonylation of dinuclear complexes 1 renders, after depalladation, the lactams 7,8-dihydro-10,11-dimethoxydibenzo[c,e]azocin-5(6H)-one (5a) and 7,8-dihydro-7,7-dimethyldibenzo[c,e]azocin-5(6H)-one (5b) or the previously reported ester derivative [2′-MeO2CC6H4C6H2CH2CH2NH3-2-(OMe)2-4,5]Br (6a) or [2′-MeO2CC6H4C6H4CH2CMe2NH3-2]Cl (6b), depending on the reaction conditions. The eight-membered palladacycles 1 react with alkenes to afford complexes [PdCl2(biarylamine)2] (7a, 7b, 8b), containing the Heck-type functionalized phenethylamines. The reaction of 1b with tBuOK in toluene at 95 °C, under a N2 atmosphere, affords 6,7-dihydro-6,6-dimethyl-5H-dibenz[b,d]azepine (9b), resulting from a C–N reductive coupling process. The crystal structures of compounds [Pd(C,N-C(═NXy)-C6H4{C6H2CH2CH2NH2-2(OMe)2-4,5)-2′})Br(CNXy)]·CH2Cl2·1/2H2O (2a·CH2Cl2·1/2H2O), [Pd(C,N-C(═NXy)-C6H4{C6H4CH2CMe2NH2-2)-2′})Cl(CNXy)]·0.72Et2O·0.28CHCl3 (2b·0.72Et2O·0.28CHCl3), and 7,8-dihydro-10,11-dimethoxydibenzo[c,e]azocin-5(6H)-one (5a) have been determined by X-ray diffraction studies.

Referência(s)
Altmetric
PlumX