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Using photochemical electron transfer, N,N-dimethylnaphthylamine derivatives are added to α,β-unsaturated carboxylates. The addition takes place exclusively in the α-position of electron-deficient alkenes and mainly in the 4-position of N,N-dimethylnaphthalen-1-amine. A minor regioisomer results from the addition in the 5-position of this naphthylamine. A physicochemical study reveals that the fluorescence quenching of N,N-dimethylnaphthalen-1-amine is diffusion-controlled and that the back electron transfer is highly efficient. Therefore no transformation is observed at lower concentrations. To overcome this limitation and to induce an efficient transformation, minor amounts of water or another proton donor as well as an excess of the naphthylamine derivative are necessary. A mechanism involving a contact radical ion pair is discussed. Isotopic labeling experiments reveal that no hydrogen is directly transferred between the substrates. The hydrogen transfer to the furanone moiety observed in the overall reaction therefore results from an exchange with the reaction medium. An electrophilic oxoallyl radical generated from the furanone reacts with the naphthylamine used in excess. Concerning some mechanistic details, the reaction is compared with radical and electrophilic aromatic substitutions. The transformation was carried out with a variety of electron-deficient alkenes. Sterically hindered furanone derivatives are less reactive under standard conditions. In a first experiment, such a compound was transformed using heterogeneous electron transfer photocatalysis with TiO(2).

A stereocontrolled synthesis of 1-cytosinyl-N-malayamycin A, an N-analogue of the naturally occurring malayamycin A with fungicidal activity, is reported. The approach was designed to rely solely on substrate control for introduction of the required stereochemistry, avoiding the use of chiral reagents or auxiliaries. Formation of the N-nucleoside was achieved through the activation of a thioglycoside, proceeding via sulfonium and thionium intermediates. Ring closure metathesis was used to build the bicyclic perhydrofuropyran heterocycle.

Recently isolated himanimide C (1) can be prepared via a short, flexible, and stereoselective synthesis using a copper-mediated tandem vicinal difunctionalization of dimethyl acetylenedicarboxylate (DMAD, 8) as a key step. The flexibility of the synthesis is exemplified by the preparation of new unnatural himanimide analogues in order to investigate the fungicidal potency of this new family. [structure: see text]