An operationally straightforward organocatalytic β-azidation of α,β-unsaturated ketones is described. Reaction of the Zhdankin azidoiodane with enones in the presence of a catalytic amount of an amine provides β-azido ketones via the formation of an electron-donor-acceptor complex. The application of this protocol is demonstrated through one-step elaborations leading to the synthesis of unprecedented classes of 1,2,3-triazoles.
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http://dx.doi.org/10.1021/acs.orglett.7b02861 | DOI Listing |
Org Lett
January 2025
Taizhou Research Institute, Southern University of Science and Technology, Taizhou 318014, Zhejiang, China.
Organocatalytic enantioselective formal nucleophilic substitution reactions of α-(2-hydroxynaphthalen-8-yl)propargyl alcohols with 1-(1-indol-3-yl)naphthalen-2-ols have been established for the first time. With the aid of a suitable chiral phosphoric acid, alkynyl 8-methylenenaphthalen-2(8)-one was formed in situ from the corresponding α-(2-hydroxynaphthalen-8-yl)propargyl alcohol, followed by enantioselective 1,6-conjugate additions of 1-(1-indol-3-yl)naphthalen-2-ols to afford a number of enantioenriched (,)-2,3-disubstituted indoles in 50-80% yields with 81-93% ee and (,)-2,3-disubstituted indoles in 18-40% yields with 79-96% ee. Notably, these nucleophilic substitution products were characterized by the presence of functional groups, including indole, naphthol, and alkynyl units, while exhibiting both axial and central chirality.
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January 2025
Institute for Organic Synthesis and Photoreactivity of the Italian National Research Council, Area della Ricerca di Bologna, Via P. Gobetti, 101, 40129 Bologna, Italy.
The utilization of the homogeneous ()-2-pyrrolidine-tetrazole organocatalyst (Ley catalyst) in the self-condensation of ethyl pyruvate and cross-aldol reactions of ethyl pyruvate donor with non-enolizable pyruvate acceptors, namely the sterically hindered ethyl 3-methyl-2-oxobutyrate or the highly electrophilic methyl 3,3,3-trifluoropyruvate, is described as the key enantioselective step toward the synthesis of the corresponding biologically relevant isotetronic acids featuring a quaternary carbon functionalized with ester and alkyl groups. The transition from homogeneous to heterogeneous flow conditions is also investigated, detailing the fabrication and operation of packed-bed reactors filled with a silica-supported version of the pyrrolidine-tetrazole catalyst (SBA-15 as the matrix).
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January 2025
Laboratoire de Chimie Agro-Industrielle (LCA), Université de Toulouse, INRAE, 4 allée Emile Monso, 31030 Toulouse, France.
In organic synthesis, the solvent is the chemical compound that represents the largest proportion of the process. However, conventional solvents are often toxic and dangerous for the environment, and an interesting alternative is to replace them by water. In this context, catalyst surfactants allow both organic reagents in water to be solubilized and organic reactions to be catalyzed.
View Article and Find Full Text PDFOrg Lett
January 2025
Department of Chemistry, Memorial University, St. John's, Newfoundland and Labrador A1B 3X7, Canada.
Organocatalytic, enantioselective decarboxylative Mannich reactions of α,β-unsaturated β'-ketoacids and isatin -Boc imines, to give the corresponding 3-carbamoyl-2-oxindole derivatives, were developed. Subsequent N-deprotection and diastereoselective, intramolecular, aza-Michael reaction of the free amine provides previously unreported spiro[indoline-3,2'-piperidine]-2,4'-diones.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Université Paris-Saclay: Universite Paris-Saclay, BioCIS, UMR 8076, 17 avenue des sciences, 17 avenue des sciences, 91405, Orsay, FRANCE.
A metal-free dual photo- and organocatalytic decarbonylation of aliphatic aldehydes is described for the first time. On the one hand, a wide range of tertiary aldehydes are smoothly decarbonylated thanks to the combination of thioxanthone as photocatalyst and diphenyl disulfide as organocatalyst. On the other hand, by simply using 4-CzIPN as photocatalyst instead of thioxanthone, various secondary aldehydes readily undergo decarbonylation in an orthogonal manner, via the in situ formation of 1,4-dihydropyridines.
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