Ecocatalysis for 2H-chromenes synthesis: an integrated approach for phytomanagement of polluted ecosystems

Abstract

A direct, general and efficient method to synthesize 2H-chromenes (2H-benzo[b]pyrans), identified as environmentally friendly pesticides, has been developed. This approach lays on the new concept of ecocatalysis, which involves the use of biomass from phytoextraction processes, as a valuable source of metallic elements for chemical synthesis. This methodology is similar or superior to known methods, affording 2H-chromenes with good to excellent yields (60-98%), including the preparation of precocene I, a natural insect growth regulator, with 91% yield. The approach is ideal for poor reactive substrates such as phenol or naphthol, classically transformed into 2H-chromenes by methodologies associated with environmental issues. These results illustrate the interest of combining phytoextraction and green synthesis of natural insecticides.

From Conventional Lewis Acids to Heterogeneous Montmorillonite K10: Eco‐Friendly Plant‐Based Catalysts Used as Green Lewis Acids

“…The yield of the reaction was 91 % and the selectivity of products A/B was 95/5 if Eco‐Zn was used without a support. In the presence of MK10, the yield was 62 % and the selectivity of A/B was 95/5 . This yield and selectivity obtained by using the plant‐based Zn catalyst were higher than those of other conventional Lewis acids, such as Zn(OTf) 2 (49 % yield), ZnCl 2 (23 % yield), or Mn(OTf) 2 (12 % yield).…”

“…The yellow solution is concentrated under vacuum then filtered through a pad of Celite if a purification step is necessary. The resulting solid residue, stored in a desiccator, may be used as an ecocatalyst or may be supported on silica or MK10 …”

“…Recently, heterogeneous, eco‐friendly, plant‐based catalysts were proposed to catalyze the synthesis of precocene I (Scheme ) and then substituted 2 H ‐chromenes (Table ) . The catalysts were obtained from Zn hyperaccumulating plants derived from N. caerulescens (Brassicaceae).…”

“…The catalysts were obtained from Zn hyperaccumulating plants derived from N. caerulescens (Brassicaceae). After calcination, acid treatment, filtration, and evaporation steps, the resulting ecocatalyst was mixed (or not) with MK10 before organic synthesis was undertaken . The mineral composition of Eco‐Zn showed the presence of many cations, such as Al (1.74 wt %), Ca (35.81 wt %), Cd (0.35 wt %), Fe (1.80 wt %), Mg (3.76 wt %), Mn (0.071 wt %), Pb (0.73 wt %), and Zn (6.57 wt %) …”

Ecological Recycling of a Bio-Based Catalyst for Cu Click Reaction: a New Strategy for a Greener Sustainable Catalysis

“…The polymetal systems obtained from the biomass produced by phytoextraction are original (unusual oxidation levels, new associated chemical species, effects of synergy). They can be used as heterogeneous catalysts in synthetic transformations giving access to molecules with high added value for fine and industrial chemicals (perfumes and cosmetics, medicines and oligomers of biological interest, highly functionalised aromatic heterocyclic compounds, key intermediaries of varied industrial chemical processes and biopesticides) …”