The Front Cover illustrates the development of continuous flow spirocyclization of 6-alkylidenepenicillanates leading to chiral spiro-β-lactams through phosphine-catalyzed [3+2] annulation of allenoates and 1,3-dipolar cycloaddition with diphenyldiazomethane. The continuous-flow synthesis of spirocyclopropanepenicillanates through thermal ring contraction of spiro-1-pyrazolinepenicillanates was also included in the study. The reported methodology is a more sustainable approach for the scale-up production of compounds with significant biological properties in high yields. More information can be found in the Research Article by T. M. V. D. Pinho e Melo and co-workers (DOI: 10.1002/ejoc.202400689).
The Front Cover shows methanolic media as a vehicle for a green, one-pot and metal-free synthetic approach to 5- and 6-membered N-heterocycle clusters, starting with benzonitriles and different available diamines and amino alcohols. The dual role of methanol as solvent and as mediated agent is supported by mechanistic and theoretical studies. More information can be found in the Research Article by I. N. Lykakis and co-workers (DOI: 10.1002/ejoc.202400601).
The Front Cover features an abstract representation of two novel, highly reducing organophotocatalysts derived from N-arylphenothiazines and N,N-diarylphenazines, compounds widely recognized as versatile and effective photoredox catalysts. The catalysts shown are the most efficient from a library of 17 catalysts synthesized. They show remarkable performance in the addition of methanol to α-methylstyrene, which was used as a model reaction, significantly reducing the reaction time and the catalyst loading by more than 20 times. Alongside the featured catalysts, the cover shows abstract representations of photophysical and photocatalytic concepts. The authors used spectroelectrochemistry and DFT calculations to further elucidate their findings and derive structure–activity relationships that might help to further improve organophotocatalysts. More information can be found in the Research Article by H.-A. Wagenknecht and co-workers (DOI: 10.1002/ejoc.202400847).
A synthesis of the five membered iminosugar DAB and a divergent synthesis of the six membered iminosugar 1-dehydromannojirimycin (DMJ) and the corresponding sugar imino acid are reported. They involve double nucleophilic displacements of a D-xylose ditriflate by benzyl carbazate and a D-glucose ditriflate by allyl amine, respectively. They are followed by a similar protocol consisting of hydrolysis and oxidation or reduction of the resulting bicyclic glycosides. This allowed DMJ to be obtained from the cheap sugar D-glucose.
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