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Given the wide utility of click-chemistry reactions for the preparation of simple moieties within large architecturally complex materials, this minireview article aims at surveying papers exploring their scope in the area of π-conjugated polymers for application in organic electronics to enable advanced functional properties.

A heterogeneous fluoride catalyst was found to enable the straightforward formation of alkenyl nitriles from the reaction of aldehydes and simple or substituted acetonitriles, in the presence of commercially available silazanes and in solvent-free conditions. The protocol afforded the products in good to excellent yields with selectivity values dependent on the nature of the substrates. It represents an alternative to classic approaches using stoichiometric strong bases, and the catalyst can be easily recovered and reused for consecutive cycles.

PS-BEMP was used as a heterogeneous catalyst for the phospha-Michael addition of phosphorus nucleophiles to a variety of electron-poor alkenes. The addition reactions were generally performed with equimolar amounts of reagents under solvent free conditions. The protocol proved to be very efficient for the addition to aromatic, non-aromatic and cyclic ketones, giving good yields (78-85%) in all cases. The protocol was also extended with good results to α,β-unsaturated esters and nitriles. This demonstrates that PS-BEMP is a good catalyst for the phospha-Michael addition to electron-poor alkenes.

Green chemistry and flow chemistry are ideal partners for accessing novel chemical spaces and define highly efficient synthetic tools. In this review article contributions have been selected according to the advantages offered in terms of features that are not immediately related to classic green metrics such as minimization of reaction time, optimization for time screening, waste minimization, safety improvement, process intensification and easy scale up, energy and cost efficiency. Such features make processes in flow highly interesting in terms of developing a green and sustainable chemistry.

The novel, environmentally friendly method allows the synthesis of 2-nitroamines from aldehydes, nitroalkanes, and aromatic amines in aqueous methanol in the absence of a catalyst.

via azidolysis of epoxides under solvent-free conditions in the presence of a polystyrene-supported bisfluoride DABCO catalyst

PS-BEMP is found to promote the title reaction (Pudovik reaction) between alkyl or aryl aldehydes (I) and diethyl phosphite (II) giving the corresponding α-hydroxyphosphonates (III) in high yields and low E-Factor values.

The cyanosilylation of carbonyl compounds (I) and (IV) using TmsCN (II) and triphenylphosphine supported on polystyrene as catalyst under solvent-free conditions is described.

The new, efficient, and recoverable bifunctional supported ammonium fluoride PAS selectively catalyzes the direct and solvent-free β-azidation of the title carboxylic acids without the need to protect/deprotect the carboxylic functionality.

Optimized conditions allow the direct synthesis of title compounds from Danishefsky′s diene and N-benzylideneanilines.

Michael and hetero-Michael addition of carbon, nitrogen, and sulfur nucleophiles to α,β-unsaturated carbonyl compounds (I) is carried out in the presence of the title catalyst.

JandaJel with its greater spacing between the linear polymeric chains compared to that of polystyrene matrices, is a very efficient support for improving the catalytic activity of TBD.

Asymmetric Henry reaction of various aromatic aldehydes is achieved in good yields and moderate to good enantioselectivities in the presence of a Cu—polymer-supported BOX complex.

The reaction of β-nitroacrylates with pyrroles, under solvent- and catalyst-free conditions, allows the formation of Friedel–Crafts adducts which, after in situ treatment with Amberlyst 15 in isopropyl alcohol under reflux, provide polysubstituted indoles, via a benzannulation reaction, in a one-pot process.

Cyclocondensation of salicylic aldehydes (I) with acetoacetate proceeds under solvent-free conditions in the presence of a solid-phase catalyst to give 3-acetylcoumarins (III) [3-nitrocoumarins (X) are formed analogously].

Epoxides and water mix well together. The use of water represents an intriguing alternative to organic solvents, not only for developing green processes but also for exploring a totally new and peculiar reactivity. Epoxides react very efficiently in water with several nucleophiles, and several examples in the literature report that the use of water as reaction medium is essential for realizing processes that cannot be performed alternatively in other reaction media. This contribution is devoted to highlight the unique role of water in the ring-opening reactions of epoxides.

This report concerns Lewis acid catalyzed enantioselective sulfa-Michael addition in neutral water by using a very efficient Sc(OTf)3/bipyridine 1 catalytic system. It is noteworthy that the protocol presented employs water as a reaction medium and allows us to obtain very high stereoselectivity and satisfactory yields for β-keto sulphides deriving from aliphatic thiols. The recovery and reuse of both the aqueous medium and the catalytic system is also reported.

A variety of terminal or internal alkynes are iodinated by the NaI/CeCl3·7H2O system to give the corresponding iodoalkenes with high regioselectivity.

The optimization of the preparation of title compounds (III) by a solvent-free aldol reaction of aryl aldehydes (I) with enol ether (II) followed by desilylation is reported.

This contribution reports the results obtained in the definition of a catalytic method for the nucleophilic ring opening of epoxides by activated methylenes promoted by a polymer-supported base. The attention has been focused on the use of polymer supported bases and the best results have been obtained by using 4-(dimethylamino)pyridine (PS-DMAP) and 2- tert -butylimino-2-diethylamino-1,3-dimethyl-perhydro-1,3,2-diazaphosphorine both on polystyrene (PS-BEMP). Solvent-free conditions has been essential for reaching a sufficient reactivity to realize this process, in fact when a reaction medium is used, the processes are almost unfeasible.

We have reported that Amberlite IRA900F (Amb-F) is an efficient metal-free catalyst for the activation of Si–N and Si–O bonds and a mild base in a variety of organic transformations under solvent-free conditions, such as the addition of TMSN3 to (E)-2-aryl-1-cyano-1-nitroethenes, nitriles, α,β-unsaturated acids and their esters, and the addition of dimethylsilylketene acetal and ethyl nitroacetate to β-nitrostyrenes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

2-tert-Butylimino -2-diethylamino-1,3 -dimethylperhydro-1,3,2 -diazaphosphorine supported on polystyrene (PS-BEMP) is an efficient catalyst for the addition of nitroalkanes (1-1.5 equiv.) to α,β-unsaturated carbonyl compounds (1.0 equiv.) in the absence of a reaction medium (solvent-free conditions). The corresponding γ-nitro carbonyl compounds have been isolated in excellent yields but the catalyst can be satisfactorily recovered and used for only 3 times due to the magnetic stirring which caused crunching of the catalyst beads thus hampering its complete recovery. To optimize the catalyst's reuse and improve the environmental efficacy of solvent-free conditions, the first solvent-free cyclic continuous-flow reactor has been set up. This reactor has allowed the product to be isolated in an almost quantitative yield by using a very small amount of organic solvent, making the recovery and reuse of the catalyst efficient and reproducible.

Because of the nitrogen functionality, the azido group plays an important role in the synthesis of amines, and numerous reduction methods of azides to primary amines are reported. Recent reports have highlighted the capability of NaI as a useful reagent for this transformation when it is used in combination with a Lewis acid promoter. However, these methods often suffer from harsh reaction conditions; for this reason, the development of a simple and efficient protocol using NaI in presence of inexpensive and readily available cerium salts Lewis acids would extend the scope of this organic transformation. In continuation of our interest on the use of the CeCl3.7H2O/NaI system, in this paper we report how azides undergo reduction by NaI in the presence of CeCl3.7H2O in refluxing acetonitrile under neutral conditions to produce the corresponding primary amines. The rate and yield of the reaction are considerably improved by employing this microwave-assisted procedure, and this may be of value for the preparation of densely functionalized molecules having biological and pharmaceutical activities.