An efficient transition-metal-based heterogeneous catalyst free procedure for obtaining the oxidative amidation of benzaldehyde using quinones as oxidizing agents in low molar proportions is described here.

The reaction mechanism for the chlorination and bromination of 2-naphthol with PIDA or PIFA and AlX₃ (X = Cl, Br), previously reported by our group, was elucidated via quantum chemical calculations using density functional theory. The chlorination mechanism using PIFA and AlCl₃ demonstrated a better experimental and theoretical yield compared to using PIDA. Additionally, the lowest-energy chlorinating species was characterized by an equilibrium of Cl–I(Ph)–OTFA–AlCl₃ and [Cl–I(Ph)][OTFA–AlCl₃], rather than PhICl₂ being the active species. On the other hand, bromination using PIDA and AlBr₃ was more efficient, wherein the intermediate Br–I(Ph)–OAc–AlBr₃ was formed as active brominating species. Similarly, PhIBr₂ was higher in energy than our proposed species. The reaction mechanisms are described in detail in this work and were found to be in excellent agreement with the experimental yield. These initial results confirmed that our proposed mechanism was energetically favored and therefore more plausible compared to halogenation via PhIX₂.

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The chlorination and bromination reaction mechanisms of 2-naphthol under the previously reported PIDA- or PIFA-AlX₃ (X= Cl, Br) systems by our research group, was elucidated via quantum chemical calculations within the density functional theory. The studied chlorination mechanism using PIFA and AlCl₃ demonstrated better experimental and theoretical yields than when PIDA was used. Additionally, the lowest-in-energy chlorinating species involve an equilibrium between the Cl-I(Ph)-OTFA-AlCl₃ and [Cl-I(Ph)+] [-OTFA-AlCl₃] species more than the PhICl₂ formation. On the other hand, the bromination mechanism was more efficient using PIDA and AlBr₃ to form the intermediate Br-I(Ph)-OAc-AlBr₃ as the brominating active species. Similarly, the PhIBr₂ is higher-in-energy than our proposal. The detailed reaction mechanisms described in this work are in excellent agreement with the experimental yields. These initial results confirm that such mechanisms are energetically more likely to occur, forming the equilibrium species than in the presence of the corresponding halogenating PhIX₂.

The induction of chirality to obtain enantiopure products of high synthetic value is of great importance across various scientific fields, particularly in the medical area, as it has been demonstrated that the different enantiomers of drugs interact differently with biological receptors. In this context, asymmetric catalysis focuses on the design of catalysts that are easy to synthesize, capable of efficiently and enantioselectively forming C–C bonds, and suitable for reuse in multiple catalytic processes. This work describes the application of a Pd(II) complex coordinated with the R and S forms of proline in direct Aldol, Morita–Baylis–Hillman, and Heck coupling reactions. The catalytic system efficiently promoted the aldol reaction, achieving yields of 80–95%, excellent diastereoselectivities (1:69 syn/anti), and enantiomeric excesses greater than 99%. From a mechanistic perspective, the formation of a transition state is proposed in which a proline molecule generates an enamine that, upon coordination with the metal center, is stabilized through interaction with the intermediate’s double bond. Moreover, the study of the Morita–Baylis–Hillman and Heck coupling reactions highlights the versatility of this type of catalyst.