Lewis acid–surfactant-combined catalyzed synthesis of 4-aminocyclopentenones from glycals in water

Natural deep eutectic solvents as an efficient and reusable active system for the Nazarov cyclization

“…24 Finally, a Nazarov cyclization performed in water in the presence of surfactants (and Lewis acids) was reported. 25 Deep eutectic solvents (DESs) have emerged as a new promising class of green solvents, since they are non-flammable, nontoxic, biodegradable and very easily prepared from cheap and readily accessible components. 26 An appropriate choice of the constituents pave the way to the design of different matrix with specific physicochemical properties.…”

One‐Pot Cascade Transformation of Glucal into Structurally Diverse Drug‐Like Scaffolds

“…In 2011, Yao and Zhang disclosed that appropriately substituted glycal substrates underwent a reaction with primary anilines in the presence of InBr 3 to provide 4‐aminocyclopentenone . In continuation of our long‐held interest in the synthesis of complex scaffolds by using simple glycals as the starting material, our group has successfully developed an environmentally benign process for the construction of 4‐aminocyclopentenone 3 by utilizing a combination of Lewis acid and surfactant to facilitate the reaction of glucal with secondary anilines in water (Scheme ) . Herein, we envisioned that the treatment of protected d ‐glucal 1 and aniline 2 with a suitable Lewis acid could lead to a cascade reaction which entailed the ring‐opening of the glucal and subsequent interrupted imino‐Nazarov reaction to ultimately furnish indoline‐fused cyclopentanone 4 in a straightforward manner.…”

“…[10] In continuation of our long-held interesti nt he synthesis of complex scaffolds by using simple glycals as the startingm aterial, [11] our group has successfullyd eveloped an environmentally benign process for the construction of 4-aminocyclopentenone 3 by utilizing ac ombination of Lewis acid and surfactant to facilitate the reactiono fg lucalw ith secondary anilinesi nw ater (Scheme 1). [12] Herein, we envisioned that the treatment of protected d-glucal 1 and aniline 2 with as uitable Lewis acid could lead to ac ascade reactionw hich entailed the ring-opening of the glucal and subsequenti nterrupted imino-Nazarov reaction to ultimately furnish indoline-fused cyclopentanone 4 in a straightforward manner.T he key feature of this protocol is the practical use of readily availableb iomass-derived glucal as the startingm aterial. This precludes the use of ah ighly toxic mercury reagent in the lengthy preparationo ft he corresponding dienal, [8] thus rendering the overall process far more step-economical and environment-friendly.…”

“…Lowering reactiontemperature to 80 8Cp rovedt ob ed etrimental as the reaction yield diminished to am ere2 9% ( Table 1, entry 8). Finally,t he cascade reaction between glycal 1 and aniline 2a was tested in av ariety of other reaction solvents such as toluene, DCE, DMF,d ioxane and nitromethane ( Table 1, entries [10][11][12][13][14]. It is notable that the choice of solventiss eemingly crucial to the success of the reaction, with nitromethane being the most superior choice in term of the reaction yield obtained.…”

Atom economical synthesis of N-alkylbenzamides via the iron(iii) sulfate catalyzed rearrangement of 2-alkyl-3-aryloxaziridines in water and in the presence of a surfactant

“…The in situ generation of a combined Lewis acid--surfactant was described in some precedents, and appears to be as effective as the direct use of the Lewis acid-surfactant catalyst. 18,19 To demonstrate the generality of this method, we next investigated the scope of this reaction under the optimized Table 2. Oxaziridines 1a--k were prepared in one pot fashion from the corresponding N--alkylamines and aromatic aldehydes according to the green method developed by our group.…”