Green chemistry is attracting increasing attention from many scientific areas proving that the development of a sustainable civilization is a common goal that can stem from numerous approaches
Within this context, chemistry certainly plays a crucial role in the design and implementation of innovative processes aimed at increasing the competitiveness and the efficiency of a modern chemical production. Organic chemistry in particular, is a pivotal research area able to contribute to the development of green chemistry in many different aspects: identification and manipulation of novel materials deriving from renewable resources, innovative and sustainable catalytic systems able to optimize known processes or access new chemical transformations, novel technologies able to increase the energy efficiency of the organic synthesis (e.g. microwave or ultrasounds irradiations, flow chemistry, …), definition of highly productive multicomponent processes, identification of new safer alternatives to replace toxic solvents. These are just some examples of the green chemistry toolbox and in this thematic issue we aim to collect original research and review articles dealing with the multidisciplinary and broad field of green organic chemistry.
Graphical Abstract
Scheme 1: Handling of azide chemistry in Tamiflu synthesis by Hayashi and co-workers [14].
Figure 1: Synthesis of compound 2 from acyl chloride 1 via Curtius rearrangement using a continuous-flow syst...
Scheme 2: Azide chemistry in the synthesis of Tamiflu.
Scheme 3: Azidation of mesyl shikimate 5.
Figure 2: Continuous-flow system for C-3 azidation of mesyl shikimate using aqueous sodium azide.
Figure 3: Mesyl shikimate azidation conversion in a continuous-flow system using NaN3.
Figure 4: Desired azide 5 selectivity in a continuous-flow system using NaN3.
Figure 5: Effect of NaN3 concentration on mesyl shikimate 4 conversion and azide 5 selectivity.
Figure 6: Regio- and stereospecific nucleophilic -N3 group attack.
Figure 7: Continuous-flow system for C-3 azidation of mesyl shikimate using DPPA or TMSA.
Figure 8: Mesyl shikimate azidation conversion in a continuous-flow system using DPPA.
Figure 9: Desired azide 5 selectivity in a continuous-flow system using DPPA.
Scheme 4: DPPA azidating mechanism in the presence of a base.
Figure 10: Effect of TEA concentration on the reaction selectivity.
Figure 11: Mesyl shikimate azidation conversion in a continuous-flow system using TMSA.
Figure 12: Desired azide 5 selectivity in a continuous-flow system using TMSA.
Figure 13: Continuous-flow system for C-3 azidation of mesyl shikimate using TBAA.
Figure 14: Continuous-flow system for C-3 azidation of mesyl shikimate using TBAA.
Scheme 5: C-5 azidation of acetamide 6 in our proposed route.
Figure 15: Continuous flow system for C-5 azidation of acetamide 6 using NaN3.
Figure 16: Continuous-flow C-5 azidation of acetamide 6 using NaN3.
Figure 17: Continuous flow C-5 azidation of acetamide 6 using various azidating agents.
Figure 18: Continuous flow synthesis of azide 7 from acetamide 6 using various azidating agents.
Graphical Abstract
Scheme 1: Palladium-catalyzed Sonogashira cross-coupling of iodobenzene (1a) and phenylacetylene (2a) in ioni...
Figure 1: Effect of catalyst precursors used in Sonogashira coupling reaction of iodobenzene (1a, 0.5 mmol) a...
Figure 2: Re-use of Pd catalyst for Sonogashira coupling of iodobenzene (1a) and phenylacetylene (2a). Reacti...
Graphical Abstract
Scheme 1: Proposed retrosynthesis of the free diol 1.
Scheme 2: Preparation of O-unprotected, trifunctionalized synthons from lactones.
Graphical Abstract
Scheme 1: [HSO3-BDBU]H2PO4-promoted oligomerization and separation.
Scheme 2: Structures of ILs used in this work.
Figure 1: Monitoring oligomerization process by 1H NMR (400 MHz, CDCl3).
Figure 2: Reusability of the IL catalyst. Reaction conditions: 10 g (30 mmol) ricinoleic acid, 190 °C, 6 h, 5...
Figure 3: 1H NMR (400 MHz, DMSO-d6) spectra of [HSO3-BDBU]H2PO4: a) Fresh one; b) used one after five cycles.
Scheme 3: Proposed mechanism for [HSO3-BDBU]H2PO4 catalyzed oligomeric ricinoleic acid synthesis.
Graphical Abstract
Scheme 1: (a) Case study 1, reaction of 4-bromotoluene; (b) case study 2, reaction of 4-bromophenylacetic aci...
Graphical Abstract
Scheme 1: The synthesis of F-1.
Figure 1: View of the crystal structure of F-1 (F-1a phase), with representation of atoms by thermal ellipsoi...
Figure 2: View of the crystal structure of F-1 (F-1a’ phase), with representation of the atoms via thermal el...
Figure 3: SEM image of F-1.
Figure 4: SEM image of F-1 with an F-1a phase.
Figure 5: TGA-DSC analysis of a sample of F-1. The TGA plot is shown in green, the DSC curve is shown in blue...
Scheme 2: Uncrystallized F-1 or F-1 with an F-1a phase promoted the two- and three-phase reactions of styrene...
Scheme 3: CAHOF F-1-promoted reactions of cyclohexene oxide (5) with alcohols and water.
Scheme 4: F-1-promoted Diels–Alder reaction.
Graphical Abstract
Figure 1: Bioactive pyrrolo[2,1-a]isoquinolines and hexahydropyrrolo[2,1-a]isoquinolines.
Scheme 1: [3 + 2] Cycloaddition with amino esters or amino acids.
Scheme 2: Scaffolds derived from the initial [3 + 2] adducts.
Scheme 3: [3 + 2] Cycloaddition with amino esters or amino acids. Conditions: 1:3:4 (1.2:1:1.1), Et3N (1.5 eq...
Scheme 4: Synthesis of pyrrolo[2,1-a]isoquinolines 9. Reaction conditions: 5 (0.5 mmol, 1 equiv), 7 (3 equiv)...
Scheme 5: Synthesis of pyrrolo[2,1-a]isoquinolines 11. Reaction conditions: 6 (0.5 mmol, 1 equiv), 7 (3 equiv...
Scheme 6: Synthesis of pyrrolo[2,1-a]isoquinolines 12. Reaction conditions: 5 or 6 (0.5 mmol, 1 equiv), cinna...
Scheme 7: Plausible mechanism for the synthesis of 9a.
Graphical Abstract
Figure 1: An approximate energy map for the electrophilic aromatic substitution mechanism.
Scheme 1: Schematic representation of the two mechanisms of Pd-catalysed C–H activation reaction considered i...
Graphical Abstract
Figure 1: FTIR analysis of βNS-CDI 1:4, before and after treatment for 4 h in H2O at 40 °C, synthesized with ...
Figure 2: Thermogravimetric analysis of β-CD-based carbonate nanosponges, obtained through solution (DMF) and...
Figure 3: Thermogravimetric analysis of α, β and γ-CD-based carbonate nanosponges, obtained through ball-mill...
Figure 4: Adsorption of organic dyes by ball-mill synthesized β-CD-based carbonate nanosponges. Conditions: a...
Figure 5: ζ-Potential of bm cyclodextrin nanosponges with relative STDev (mV).
Figure 6: Hydrolysis of the imidazoyl carbonyl group in water at 40 °C.
Figure 7: Nitrogen content in weight % in cyclodextrins NS-CDI from ball mill synthesis. a) comparison betwee...
Figure 8: Simplified schematic reaction and procedure for obtaining the dye-functionalized βNS-CDI. Surface z...
Graphical Abstract
Scheme 1: Conversion of cellulose to isosorbide.
Scheme 2: Combination of mineral acids or heteropolyacids and a supported metal catalyst to produce isosorbid...
Scheme 3: Conversion of sorbitol to isosorbide via the formation of sorbitans.
Scheme 4: Conversion of cellulose to isosorbide in the presence of heteropolyacids and metal-supported cataly...
Scheme 5: Summary of the results obtained in one-pot one step processes [21-25].
Scheme 6: Conversion of (ligno)cellulose to isosorbide in the presence of Amberlyt 70 and a Ru/C catalyst [26,27].
Scheme 7: Use of Ru-supported on mesoporous nobium phosphate (mNbPO) for the synthesis of isosorbide from cel...
Graphical Abstract
Figure 1: The benzimidazoles I–IV, dihydropyrimidinones/-thiones V–VIII, and 2-amino-4-aryl-3,5-dicarbonitril...
Scheme 1: NDL-catalyzed synthesis of i) 1,2-disubstituted benzimidazoles 3, ii) dihydropyrimidinones/-thiones ...
Figure 2: XRD pattern of the NDL catalyst.
Figure 3: FTIR spectrum of the NDL catalyst.
Figure 4: Raman spectrum of the NDL catalyst.
Figure 5: SEM images of the NDL catalyst.
Figure 6: EDAX analysis of the NDL catalyst.
Scheme 2: Unexpected formation of the bisimine I, 3h, from o-phenylenediamine (1) and salicylaldehyde (2h).
Figure 7: 1H NMR spectrum of 2,2'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis (methanylylidene))diphenol (...
Figure 8: XRD pattern of a) the fresh NDL catalyst; b) the recovered NDL catalyst after the 7th cycle of the ...
Graphical Abstract
Scheme 1: One-pot synthesis of 2,5-diarylpyrazines (A) (path a) or 2-aroyl-(4 or 5)-aryl-(1H)-imidazoles (B) ...
Scheme 2: Transformation of phenacyl bromide (1a) in ChCl/Gly into phenacyl azide (2a) and 2-benzoyl-(4 or 5)...
Scheme 3: Synthesis of 2-aroyl-(4 or 5)-aryl-(1H)-imidazoles 3. Scope of the reaction. Typical conditions: 1 ...
Scheme 4: Proposed mechanism for the formation of 2-aroyl-(4 or 5)-aryl-(1H)-imidazoles 3/3' from α-phenacyl ...
Scheme 5: Proposed mechanism for the formation of 2-benzoyl-(4 or 5)-phenyl-(1H)-imidazoles 3a/3a' and 2,4-di...
Scheme 6: Scope of the synthesis of 2,4-diaroyl-6-arylpyrimidines 7. Typical conditions: 2 (0.3 mmol), Et3N (...
Graphical Abstract
Scheme 1: Synthesis of NHC-supported catalysts.
Scheme 2: Negishi benchmark reaction.
Figure 1: Negishi reaction catalyzed by immobilized NHC–Pd complexes. Conditions: methyl 4-bromobenzoate (0.2...
Scheme 3: Synthesis of immobilized NHC–Pd–RuPhos.
Figure 2: Negishi model reaction between 5 and 6 under flow conditions catalyzed by 4b. V = 0.535 mL, 363 mg ...
Figure 3: Negishi model reaction under flow conditions catalyzed by 8a. V = 2.9 mL, 1.25 g of catalyst, resid...
Figure 4: Negishi reaction between 5 and 6 catalyzed by 8a in the presence of SILLPs. a) Yield (%) vs time fo...
Figure 5: TEM images of the polymers after the Negishi reaction between 5 and 6. a) 8a, bar scale 20 nm, PdNP...
Scheme 4: Pd species immobilized onto SILLPs. i) 1 g SILLP 10, 100 mg PdCl2 in milli-Q® water (100 mL 1% HCl,...
Figure 6: Negishi reaction between 5 and 6 catalyzed by 11. 1 equiv methyl 4-bromobenzoate (6, 0.25 mmol), 2 ...
Figure 7: Negishi reaction between 5 and 6 under flow conditions catalyzed by 8a in the presence of a scaveng...
Figure 8: Effect of the structure of the SILLP scavenger for the Negishi reaction between 5 and 6 under flow ...
Figure 9: TEM images of the polymer after the Negishi reaction between 5 and 6 under flow conditions. a) 8a + ...
Graphical Abstract
Figure 1: Radial diamond diagrams illustrating the sustainability index (SI) computed based on FVI, FVO, FVP,...
Graphical Abstract
Scheme 1: Pathway for the formation of ChNC and subsequently ChsNCs from bulk chitin.
Figure 1: TEM micrographs of (a) ChNCs and (b) ChsNCs. Both samples were stained and prepared on glow-dischar...
Scheme 2: Catalyst fabrication method for the deposition of Pd NPs onto chitin (PdNP@ChNC) and chitosan (PdNP...
Figure 2: TEM micrographs of (a) PdNP@ChNCs and (b) PdNP@ChsNCs. The samples were placed on glow discharged T...
Figure 3: High-resolution X-ray photoelectron spectroscopy of the Pd 3d region of (a) PdNP@ChNC and (b) PdNP@...
Graphical Abstract
Scheme 1: The classical Hantzsch synthesis between benzaldehyde (1a), ethyl acetoacetate (2), and ammonium ac...
Figure 1: Optimization trials with the selected solid catalysts.
Figure 2: Graphical representation of the results obtained in the reusability test.
Graphical Abstract
Figure 1: Schematic illustration for the preparation of the catalyst in this work.
Figure 2: FTIR spectra of LS, LS-FAS, and LS-FAS-Cu.
Figure 3: Thermogravimetric weight loss of the obtained materials LS-FAS and LS-FAS-Cu.
Figure 4: FSEM imagine of LS-FAS-Cu in different scale label a) 1 μm, b) 200 nm; FTEM images of LS-FAS-Cu in ...
Figure 5: XPS spectra of LS-FAS-Cu in the regions of C 1s, O 1s, Cu 2p3/2 and Cu LMM (inset).
Scheme 1: Substrate scope of LS-FAS-Cu catalyzed three-component reactions of 4-aminoindoles, alkynes and ald...
Figure 6: Recyclability of LS-FAS-Cu, LS-FM-Cu and Resin-Cu in the reaction between compounds 1a, 2a and 3a.
Graphical Abstract
Figure 1: Representative biologically active N-(hetero)aryl-4,5-unsubstituted pyrrole scaffolds.
Scheme 1: Typical routes to N-(heteroaryl)-4,5-unsubstituted pyrroles.
Scheme 2: Substrate scope of the pyrrole synthesis.
Scheme 3: Synthesis of N-heterocyclic pyrroles.
Scheme 4: Direct synthesis of pyrrole-3-carboxamide derivatives.
Scheme 5: Plausible mechanism of the three-component reaction.
Scheme 6: Synthesis of polysubstituted pyrazolo[3,4-b]pyridine derivatives.
Graphical Abstract
Scheme 1: Synthesis of α-amino-acetonitrile derivatives. Reaction conditions: Aldimine (1 equiv), TMSCN (1 eq...
Figure 1: Crystal structure of 2-phenothiazinyl-2-(p-tolylamino)acetonitrile 2a. a) ORTEP plot and b) crystal...
Figure 2: SEM images recorded at 200× for the raw reaction product 2b obtained through a) ultrasound-assisted...
Figure 3: SEM image recorded at 200× for the raw reaction product 2c obtained through a) ultrasound-assisted ...
Graphical Abstract
Scheme 1: Synthesis of biarenes via a) photogenerated triplet aryl cations and aryl radicals (PC = photocatal...
Scheme 2: Metal-free photochemical synthesis of biaryls 2 and 4.
Figure 1: Emission spectrum of compound 1e (red) and of diethyl p-tert-butylphenyl phosphate (black) in metha...
Figure 2: Emission spectrum of compound 1h (red) and of diethyl p-cyanophenyl phosphate (black) in methanol.
Figure 3: Emission spectrum of compound 3a in methanol (black) and in a methanol/TFE 4:1 mixture (red).
Figure 4: Emission spectrum of 3c in MeOH (dotted line) and in the presence of increasing amounts of TFE (up ...
Scheme 3: Photoreactivity of aryl phosphates 1 and 3 in protic media.
Graphical Abstract
Scheme 1: Benzylic addition of aldehydes to azaarenes using different catalysts.
Scheme 2: Synthesis of azaarene derivatives from different precursors.
Scheme 3: Our work: catalyst- and solvent-free benzylic addition of aldehydes to azaarenes.
Scheme 4: Large-scale experiments for the synthesis of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (...
Scheme 5: Plausible mechanism for the formation of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (3a) ...
Graphical Abstract
Scheme 1: Flow generation and transformation of 2H-azirines.
Scheme 2: Flow synthesis of 2H-azirines from vinyl azides. aThe solution of vinyl azide was re-introduced twi...
Scheme 3: Mixed flow-batch approach for the preparation of functionalized NH-aziridines from vinyl azides.
Graphical Abstract
Figure 1: Bioactive molecules containing the 2-aminoquinoline motif.
Scheme 1: C2-selective C–N bond formation of N-oxides.
Scheme 2: Substrate scope of N-sulfonyl-1,2,3-triazoles. Reaction conditions: 1a (0.2 mmol), 2 (0.24 mmol) an...
Scheme 3: Substrate scope of quinoline N-oxides. Reaction conditions: 1 (0.2 mmol), 2a (0.24 mmol) and DCE (2...
Scheme 4: Late-stage modification of natural products.
Scheme 5: Substrate scope for the reaction of substituted triazoles with isoquinoline N-oxide.
Scheme 6: Gram-scale and one-pot synthesis.
Scheme 7: Proposed mechanism.
Graphical Abstract
Figure 1: A) Tetracyclic core of steroids and possible sites of bond cleavages for secosteroids. B)The first ...
Scheme 1: Retrosynthetic analysis of 9,11-secosterols.
Scheme 2: Synthesis of starting materials. Reagents and conditions: i) NaBH4, EtOH/CH2Cl2 1:1, 2 h, rt, then ...
Scheme 3: Oxidation of diols 5 and 6 with NaOCl·5H2O.
Graphical Abstract
Figure 1: Potential classification of plastic recycling processes. The area covered by the present review is ...
Figure 2: EG produced during glycolytic depolymerisation of PET using DEG + DPG as solvent and titanium(IV) n...
Scheme 1: Simplified representation of the conversion of 1,4-PBD to C16–C44 macrocycles using Ru metathesis c...
Figure 3: Main added-value monomers obtainable by catalytic depolymerisation of PET via chemolytic methods.
Scheme 2: Hydrogenolytic depolymerisation of PET by ruthenium complexes.
Scheme 3: Depolymerisation of PET via catalytic hydrosilylation by Ir(III) pincer complex.
Scheme 4: Catalytic hydrolysis (top) and methanolysis (bottom) reactions of PET.
Scheme 5: Depolymerisation of PET by glycolysis with ethylene glycol.
Figure 4: Glycolysis of PET: evolution of BHET yield over time, with and without zinc acetate catalyst (196 °...
Scheme 6: Potential activated complex for the glycolysis reaction of PET catalysed by metallated ILs and evol...
Scheme 7: One-pot, two-step process for PET repurposing via chemical recycling.
Scheme 8: Synthetic routes to PLA.
Scheme 9: Structures of the zinc molecular catalysts used for PLA-methanolysis in various works. a) See [265], b) ...
Scheme 10: Depolymerisation of PLLA by Zn–N-heterocyclic carbene complex.
Scheme 11: Salalen ligands.
Scheme 12: Catalytic hydrogenolysis of PLA.
Scheme 13: Catalytic hydrosilylation of PLA.
Scheme 14: Hydrogenative depolymerisation of PBT and PCL by molecular Ru catalysts.
Scheme 15: Glycolysis reaction of PCT by diethylene glycol.
Scheme 16: Polymerisation–depolymerisation cycle of 3,4-T6GBL.
Scheme 17: Polymerisation–depolymerisation cycle of 2,3-HDB.
Scheme 18: Hydrogenative depolymerisation of PBPAC by molecular Ru catalysts.
Scheme 19: Catalytic hydrolysis (top), alcoholysis (middle) and aminolysis (bottom) reactions of PBPAC.
Scheme 20: Hydrogenative depolymerisation of PPC (top) and PEC (bottom) by molecular Ru catalysts.
Scheme 21: Polymerisation-depolymerisation cycle of BEP.
Scheme 22: Hydrogenolysis of polyamides using soluble Ru catalysts.
Scheme 23: Catalytic depolymerisation of epoxy resin/carbon fibres composite.
Scheme 24: Depolymerisation of polyethers with metal salt catalysts and acyl chlorides.
Scheme 25: Proposed mechanism for the iron-catalysed depolymerisation reaction of polyethers. Adapted with per...
Graphical Abstract
Scheme 1: Synthesis, functionalization and applications of triazoles.
Scheme 2: The reaction was performed using 0.2 mmol N-tosyl-1,2,3-triazole 1 and 0.2 mmol of cyclohexyl-1,3-d...
Scheme 3: Control experiments.
Scheme 4: Mechanistic proposal for the formation of β-triazolylenones.
Figure 1: Nucleophilic addition to 5- and 6-membered cyclic tosyloxyenones.
Graphical Abstract
Scheme 1: AB-mediated reductions of nitrostyrenes 3a–h.
Scheme 2: AB-mediated reductions of nitrostyrenes 1, 3a, and 3c using DESs B and D.
Scheme 3: AB-mediated reductions of nitroalkenes 5a–f.
Scheme 4: Recovery and recycling experiments in the AB-mediated reduction of nitrostyrene 3h to afford nitroa...