Dioxomolybdenum Complexes as Excellent Catalysts for the Deoxygenation of Aryl Ketones to Aryl Alkenes

Reactivity of metal dioxo complexes

Metal dioxo chemistry and its diverse reactivity are presented with an emphasis on the mechanisms of reactivity. Work from approximately the last decade is surveyed and organized by metal. In particular, the chemistry of cis-dioxo metal complexes is discussed at length. Reactions are grouped by generic type, including addition across a metal oxo bond, oxygen atom transfer, and radical atom transfer reactions. Attention is given to advances in deoxygenation chemistry, oxidation chemistry, and reductive transformations.

Triflic Acid/Silane Promoted Deoxygenative Transformation of Ketones via Carbocations

Deoxygenative transformation of ketones into value-added products often suffers from precious-metal-based catalysts or complicated operational conditions. Triflic acid and silane serve as a cooperative reductant to transform ketones via carbocations that undergo β-H elimination much faster than hydride transfer from silane to produce alkenes with high selectivity. Alternatively, the presence of indoles would incept the protonated ketones to generate carbocations, allowing access to Csp2-Csp3 bond formation with high reactivity and selectivity in "one pot".

Depolymerization of P4HB and PBS Waste and Synthesis of the Anticancer Drug Busulfan from Plastic Waste

Sustainable synthesis of pharmaceuticals is one of the main challenges for the pharmaceutical industry. Production of these compounds from plastic waste can provide an innovative and ecological approach to their sustainable synthesis. In this context, plastic waste can be regarded as a potential cheap resource for the production of compounds of interest to the pharmaceutical industry. In this work, the first methodologies for the reductive depolymerization of poly(4-hydroxybutyrate) (P4HB) and polybutylene succinate (PBS) plastic waste are reported using the catalyst systems MoO2Cl2(H2O)2/silane, MoO2Cl2(H2O)2/borane and KOH/PhSiH3 with moderate to excellent yields. We also developed the first synthetic strategy for the synthesis of a drug, the anticancer busulfan, from P4HB and PBS plastic waste with moderate overall yields.

Phosphonate Decomposition-Induced Polyoxomolybdate Dumbbell-Type Cluster Formation: Structural Analysis, Proton Conduction, and Catalytic Sulfoxide Reduction

The reaction of MoO₄^2- with a number of phosphonic acids [bis(phosphonomethyl)glycine, R,S-hydroxyphosphonoacetic acid, 1-hydroxyethane-1,1-diphosphonic acid, phenylphosphonic acid, aminotris(methylene phosphonic acid), and 1,2-ethylenediphosphonic acid] under oxidizing (H₂O₂) hydrothermal conditions at low pH leads to rupture of the P-C bond, release of orthophosphate ions, and generation of the octanuclear, phosphate-bridged, polyoxometalate molybdenum cluster (NH₄)₅[Mo₈(OH)₂O₂₄(μ₈-PO₄)](H₂O)₂ (POMPhos). This cluster has been fully characterized and its structure determined. It was studied as a proton conductor, giving moderate values of σ = 2.13 × 10^-5 S·cm^-1 (25 °C) and 1.17 × 10^-4 S·cm^-1 (80 °C) at 95% relative humidity, with E_a = 0.27 eV. The POMPhos cluster was then thermally treated at 310 °C, yielding (NH₄)_2.6(H₃O)_0.4(PO₄Mo₁₂O₃₆) together with an amorphous impurity containing phosphate and molybdenum oxide. This product was also studied for its proton conductivity properties, giving rise to an impressively high value of σ = 2.43 × 10^-3 S·cm^-1 (25 °C) and 6.67 × 10^-3 S·cm^-1 (80 °C) at 95% relative humidity, 2 orders of magnitude higher than those corresponding to the "as-synthesized" solid. The utilization of POMPhos in catalytic reduction of different sulfoxides was also evaluated. POMPhos acts as an efficient homogeneous catalyst for the reduction of diphenyl sulfoxide to diphenyl sulfide, as a model reaction. Pinacol was used as a low-cost, environmentally friendly, and highly efficient reducing agent. The effects of different reaction parameters were investigated, namely the type of solvent and reducing agent, presence of acid promoter, reaction time and temperature, loading of catalyst and pinacol, allowing to achieve up to 84-99% yields of sulfide products under optimized conditions. Substrate scope was tested on the examples of diaryl, alkylaryl, dibenzyl, and dialkyl sulfoxides and excellent product yields were obtained.