Addition of lithium amides (LiNR ₂ ) to carbodiimides/nitriles was achieved in sustainable solvents, under air, allowing the synthesis of guanidines/amidines.

Two series of boron derivatives with propiolamidinato ligands, [BPh2{C(C CAr)(NR)(2)}] (Ar = Ph, p-MeOPh, p-FPh, p-Me2NPh, or phen; R = iPr or p-tolyl), were synthesized and structurally characterized. The corresponding propiolamidine (or propargylamidine) proligands have been obtained through sustainable methods. One is the catalytic hydroalkynylation of diisopropylcarbodiimide with different terminal alkynes, using simple ZnEt2 as a precatalyst. Alternatively, to obtain propiolamidines with aromatic groups on the nitrogen atoms, the formation of lithiated derivatives of terminal alkynes by reaction with n-BuLi in air and at room temperature, and subsequent addition to the di-p-tolylcarbodiimide, under the same conditions and using 2-MeTHF as a sustainable solvent, has been used for the first time. After reaction with BPh3, the corresponding boron amidinates were obtained, which are emissive in the solution state. The influence of the different substituents introduced into the ligands on the photophysical properties of the boron compounds has been studied. One of the obtained compounds can be used as a ratiometric fluorescent pH sensor in the acidic range.

The modular synthesis of the guanidine core by guanylation reactions using commercially available ZnEt₂ as a catalyst has been exploited as a tool for the rapid development of antitumoral guanidine candidates. Therefore, a series of phenyl-guanidines were straightforwardly obtained in very high yields. From the in vitro assessment of the antitumoral activity of such structurally diverse guanidines, the guanidine termed ACB3 has been identified as the lead compound of the series. Several biological assays, an estimation of AMDE values, and an uptake study using Fluorescence Lifetime Imaging Microscopy were conducted to gain insight into the mechanism of action. Cell death apoptosis, induction of cell cycle arrest, and reduction in cell adhesion and colony formation have been demonstrated for the lead compound in the series. In this work, and as a proof of concept, we discuss the potential of the catalytic guanylation reactions for high-throughput testing and the rational design of guanidine-based cancer therapeutic agents.

Surpassing the tradition, experimental and DFT calculations showed the crucial role of water in the selective synthesis of tetrahydropyridines, aminoketones or enamines via allyl Grignard addition to nitriles, unmatched by dry organic solvents.

Azolium-2-thiocarboxylate zwitterion ligands have emerged as a promising class of compounds in the field of coordination chemistry due to their unique structural features and versatile applications. These ligands are characterized by a positively charged azolium ring and a negatively charged thiocarboxylate moiety, making them capable of forming stable coordination complexes with various metal ions. One of the key structural aspects that make these ligands attractive for coordination chemistry is their ability to adopt diverse coordination modes with metal centers. The nature of these ligands enables them to engage in both monodentate and bidentate coordination, resulting in the formation of chelated complexes with enhanced stability and controlled geometry or the formation of polynuclear structures. This versatility in coordination behavior allows for the design of tailored ligands with specific metal-binding preferences, enabling the creation of unique and finely tuned coordination architectures. The azolium-2-thiocarboxylate zwitterionic ligands offer a promising platform for the design of coordination complexes with diverse structural architectures.

Polydentate ligands with nitrogen donor atoms have possibly given rise to the largest group of coordination complexes described. Among these ligands, amidinates represent a nitrogenated version of carboxylates and allow the formation of complexes with most elements in the periodic table, adopting chelate or bridge coordination modes. The precursors of these ligands, amidines, can present an alkynyl group as the substituent of their central atom, R′N=C(C≡CR)NHR′, which provides an additional point of reactivity for these molecules, as well as a different electronic behavior compared to conventional amidines with alkyl groups on the central carbon atom of the amidine group. These propiolamidines have been obtained through classical stoichiometric organic synthesis procedures or, with greater atomic economy, through catalytic procedures based on Main Group, Transition, or Rare Earth metals. This work reviews these synthesis methods, as well as the reactivity in the obtention of new, more complex heterocyclic organic molecules.