Publications by authors named "Marco Antonio Barbosa Ferreira"

Advancements in synthetic organic chemistry are closely related to understanding substrate and catalyst reactivities through detailed mechanistic studies. Traditional mechanistic investigations are labor-intensive and rely on experimental kinetic, thermodynamic, and spectroscopic data. Linear free energy relationships (LFERs), exemplified by Hammett relationships, have long facilitated reactivity prediction despite their inherent limitations when using experimental constants or incorporating comprehensive experimental data.

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Herein, we report a fully detailed mechanistic study involving an organocatalyzed 1,3-dipolar cycloaddition enolate or stabilized vinylogous carbanion intermediates and azide for the synthesis of 1,2,3-triazoles. A detailed investigation of the elementary steps, intermediates, and transition states of the two organocatalyzed metal-free click reactions is supported by DFT calculations and H NMR monitoring experiments, providing detailed profiles for both reaction mechanisms. Distortion-interaction activation-strain (DIAS) analysis was also employed to further elucidate the regioselectivity in both reactions.

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Chiral molecules in nature are involved in many biological events; their selectivity and specificity make them of great interest for understanding the behavior of bioactive molecules, by providing information about the chiral discrimination. Inspired by these conformational properties, we present the design and synthesis of novel chiral platinum(II) complexes featuring phosphine and chloroquine ligands with the general formula [PtCl(P)2(CQ)]PF6 (where (P)2 = triphenylphosphine (PPh3) (5), 1,3-bis(diphenylphosphine)propane (dppp) (6), 1,4-bis(diphenylphosphine)butane (dppb) (7), 1,1'-bis(diphenylphosphine)ferrocene (dppf) (8), and CQ = chloroquine] and their precursors of the type [PtCl2(P)2] are described. The complexes were characterized by elemental analysis, absorption spectroscopy in the infrared and ultraviolet-visible (UV-vis) regions, multinuclear ((1)H, (13)C, (31)P, (15)N, and (195)Pt) NMR spectroscopy, cyclic voltammetry, and mass spectrometry (in the case of chloroquine complexes).

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