title: MoCl5 as an effective chlorinating agent towards α-amino acids: synthesis of α-ammonium-acylchloride salts and α-amino-acylchloride complexes.
abstract: The reactivity of MoCl5 with α-amino acids was investigated for the first time by choosing CH2Cl2 as the reaction medium. The interaction of MoCl5 with l-proline proceeded with Cl/O interchange and led to the formation of [NH2(CH2)3CHC(O)Cl][MoOCl4], 1, in 63% yield. The reactions of MoCl5 with l-phenylalanine, sarcosine, N,N-dimethylglycine and N,N-dimethyl-l-phenylalanine afforded the α-amino-acylchloride complexes MoOCl3[O[double bond, length as m-dash]C(Cl)CH(R)N(R')(R'')] (R = CH2Ph, R' = R'' = H, 2a; R = R' = H, R'' = Me, 2b; R = H, R' = R'' = Me, 2c R = CH2Ph, R' = R'' = Me, 2d), in ca. 70% yields. According to DFT studies, 2a,d are mononuclear Mo(v) octahedral complexes bearing a N,O-coordinated α-amino-acylchloride ligand. The presumed species formed during the first stages of the MoCl5/l-phenylalanine interaction were DFT-elucidated, thus the calculated Gibbs free energy profile for the multi-step reaction of MoCl5 with l-phenylalanine was traced. [NH3CH(CH2Ph)C(O)Cl][MoOCl4], 3, acting as an intermediate in the course of the formation of 2a, was isolated by combination of [NH3CH(CH2Ph)C(O)Cl][Cl] with MoOCl3.
authors.affiliation: Ca' Foscari University of Venezia, Dipartimento di Scienze Molecolari e Nanosistemi, Dorsoduro 2137, I-30123 Venezia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bortoluzzi
authors.forename: Giulio
authors.initials: G
authors.lastname: Bresciani
authors.forename: Fabio
authors.initials: F
authors.lastname: Marchetti
authors.forename: Guido
authors.initials: G
authors.lastname: Pampaloni
authors.forename: Stefano
authors.initials: S
authors.lastname: Zacchini
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D054879:Halogenation; D008982:Molybdenum / Q000737:chemistry*; D012492:Salts / Q000737:chemistry
chemical_list: D000596:Amino Acids; D002712:Chlorides; D012492:Salts; D008982:Molybdenum; C085192:molybdenum chloride