Reactivity of Eight-Membered Palladacycles Arising from Monoinsertion of Alkynes into the Pd–C bond of Ortho-Palladated Phenethylamines toward Unsaturated Molecules. Synthesis of Dihydro-3-Benzazocinones, N 7 -amino Acids, N 7 -amino Esters, and 3-Benzazepines
2013; American Chemical Society; Volume: 33; Issue: 1 Linguagem: Inglês
10.1021/om4010059
ISSN1520-6041
AutoresMaría‐José Oliva‐Madrid, José-Antonio Garcı́a-López, Isabel Saura‐Llamas, Delia Bautista, José Vicente,
Tópico(s)Cyclopropane Reaction Mechanisms
ResumoFrom the reactions of isocyanides R3NC with some eight-membered palladacycles arising from the insertion of one molecule of alkyne into the Pd–C bond of the palladacycles derived from homoveratrylamine and phentermine it is possible to isolate three different types of mononuclear complexes containing (1) coordinated R3NC, (2) coordinated and inserted R3NC, or (3) an unprecedented η3-allyl ligand involving a ketenimine moiety. These complexes decompose under the appropriate conditions to afford metallic palladium and the corresponding eight-membered azacycles arising from C–N coupling processes. The eight-membered palladacycles react with CO in MeOH to yield Pd(0) and amino esters. A singular isomerization process from a fumarate to a maleate was observed and studied by DFT. When the reaction with CO is carried out in the presence of TlTfO, N7-amino acid derivatives can be obtained. This synthetic method can also be used to prepare the N5-amino acids derived from the ortho-metalated homoveratrylamine or phentermine. Finally, the treatment of one eight-membered palladacycle derived from phentermine with KtBuO in refluxing toluene, followed by addition of HTfO, afforded Pd(0) and a dihydro-3-benzazepinium salt. Crystal structures of every type of compound have been determined by X-ray diffraction studies.
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