The concept of green chemistry began in the USA in the 1990s. Since the publication of the 12 principles of this concept, many reactions in organic chemistry have been developed, and chemical products have been synthesized under environmentally friendly conditions. Lewis acid mediated synthetic transformations are by far the most numerous and best studied. However, the use of certain Lewis acids may cause risks to environmental and human health. This Review discusses the evolution of Lewis acid catalyzed reactions from a homogeneous liquid phase to the solid phase to yield the expected organic molecules under green, safe conditions. In particular, recent developments and applications of biosourced catalysts from plants are highlighted.

In western Europe, xeric sandy calcareous grasslands have been reduced to a few small and isolated fragments, as a result of sand quarrying and abandonment of agro‐pastoral practices leading to tree encroachment. The restoration of dry grasslands usually consists of reopening the land by cutting trees and removing the litter or the topsoil, relying on seed rain and soil seed bank for recolonization. We investigated whether the soil seed bank of degraded sandy grasslands can be a suitable tool in the restoration of typical sandy grassland communities. We examined the soil seed bank and the vegetation composition in a total of 20 plots of extant and recently restored sandy grasslands (Sedo‐Cerastion) in southern Belgium. Seed density ranged from 611 to 38,808 seeds/m2. Dry grassland species accounted for 42% of the soil seed bank in extant grasslands but dropped to 17% for restored sites, which were dominated by species from artificial pioneer habitats. Only a small number of the 122 species recorded in the vegetation germinated from the soil seed bank samples. Most of these were common species with large ecological amplitude (e.g., Arenaria serpyllifolia, Poa annua, and Rumex acetosella), already present in the site. The typical sandy grassland specialists (e.g., Cardaminopsis arenosa, Dianthus deltoides, Helichrysum arenarium, and Petrorhagia prolifera) were missing from the seed bank, except when present in the vegetation. Therefore, a successful restoration of degraded sandy grasslands based on local seed banks is unlikely. Additional management actions, such as active seed sowing of target species, may be necessary.

The effects of P-fertilizers (mono- and di-calcium phosphates) on the bioavailability of metals and nutrients in leaves and stems of Miscanthus × giganteus were studied in mesocosm and field experiments in order to propose a new way for the valorization of miscanthus biomass. The concentration of potentially toxic elements was generally higher in stems than in leaves. Although P-fertilizers were added to contaminated soils under sustainable conditions (from 0.022% to 0.026% w/w), the average of leaf and stem biomass generally increased in the presence of P-fertilizers due to the changes in the speciation of phosphorus. Leaves of the investigated miscanthus may be of great interest as a catalyst in organic chemistry, since the Ca concentration was up to 9000 mg kg−1 DW. Stems represent a potential biomass that can be used as renewable resource of Lewis acids, currently used in organic syntheses (the sum of Zn, Cu, Mn, Fe, Mg, Si and Al was near 1000 mg kg−1 DW). The percentage of Cd and Pb in leaves and stems of miscanthus did not significantly change with P-fertilizers. Depending on the mesocosm and field experiments, it ranged from 0.004% to 0.016% and from 0.009% and 0.034% for Cd in leaves and stems, respectively, and from 0.004% to 0.015% and from 0.009% and 0.033% for Pb in leaves and stems, respectively.

Effects of three phosphorus fertilizers on the shoot biomass and on the accumulation of alkali, alkaline earth, and transition metals in the shoots and roots of ryegrass were studied with two contaminated garden soils. Phosphates were added in sustainable quantities in order to reduce the environmental availability of carcinogenic metals (e.g., Cd and Pb) and to enhance the bioavailability of alkali and alkaline earth metals as well as micronutrients needed by plants. Addition of Ca(H2PO4)2 was the most convenient way to (i) limit the concentration of Cd and Pb, (ii) keep constant the transfer of macro- and micronutrient from the soil to the ryegrass shoots, (iii) decrease the availability of metals, and (iv) increase the ratio values between potential Lewis acids and Cd or Pb in order to produce biosourced catalysis. For instance, the real phytoavailability was reduced by 27%–57% and 64.2%–94.8% for Cd and Pb, respectively. Interestingly, the real phytoavailability of Zn was the highest in the least contaminated soils. Even if soils were highly contaminated, no visual toxicity symptoms were recorded in the growing ryegrasses. This indicates that ryegrass is suitable for the revegetation of contaminated gardens. To promote the sustainable ryegrass production on contaminated soils for production of new organic fragrance and drugs in green processes according to REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals) regulation, two processes should be recommended: assisted phytostabilization of the elements, and then assisted phytoextraction by using chelators.

A new environmentally friendly approach for the synthesis of idrocilamide (1), a marketed myorelaxant and anti‐inflammatory agent, is reported herein. The synthetic strategy involves a solvent‐free aminolysis reaction catalyzed by zinc‐containing species (ZnCl2, montmorillonite K10 (MK10) impregnated with ZnCl2 or eco‐catalysts). The latter have been prepared from the aerial parts of Lolium perenne L. plants grown on contaminated soils from northern France without and with thermal activation at 120 °C and supported on MK10 (Ecocat1 and Ecocat2, respectively). The best aminolysis catalysts in the current study (ZnCl2 and Ecocat2) were selected for additional aminolyses. Compared to ZnCl2, Ecocat2 had the advantage of being reusable over five test runs and constituted a sustainable catalyst allowing a green route to idrocilamide. Synthesized derivatives 1–4, 6 and 9 were first evaluated for their effect on reactive oxygen species (ROS) generation from macrophages and displayed antioxidant properties by preventing ROS production. Next, the analysis of the effect of molecules 1–4, 6 and 9 on macrophage migration between epithelial cells to human opportunistic fungus Candida albicans indicated that molecules 2–4, 6 and 9 exert anti‐inflammatory properties via reducing macrophage migration while the parent idrocilamide (1) did not show any significant effect. This work opens the way for the discovery of new analogues of idrocilamide with improved properties.