Synthesis of .delta.-lactones via radical carbon-carbon bond formation using chiral radical precursors

Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents

“…A Giese reaction can be performed where the radical adds to an electron-poor alkene and this gives the alkylated compounds 85. 99,100 The use of vinyl sulfones in combination with a carbon-centred radical led to the formation of vinyl compounds 86 (following loss of the sulfonyl radical) 101,102 The use of ethynyl-benziodoxolone (EBX) reagents allowed for the preparation of alkyne compounds 87 with carbon-centred radicals under mild conditions. 103 Carboncentred radicals were used in the Minisci reaction, with functionalised heterocycles 88 being produced.…”

Biocatalysis in Organic Synthesis: The Use of Nitrile- and Amide-hydrolyzing Microorganisms

“…2) In contrast, they are conventionally prepared by introduction of one carbon as cyanide ion (eN 3) two carbon homologation by the use of a cyanoacetate equivalent,4) and three carbon homologation with acrylonitrile as the Michael acceptor of radical species. 5 ) Hydrolysis of nitriles* 1 proceeds in two steps. In the step to amides, proton (H +) and/or metal cationic species (M+) work to activate the carbon-nitrogen triple bond, which facilitates the addition of water molecules.…”

Synthèse des (−)‐(6R)‐et(+)‐(6S)‐tétrahydro‐6‐[(Z)‐pent‐2‐ényl]‐2H‐pyran‐2‐one, lactones de Jasminum grandiflorum L. et de Polianthes tuberosa L.

“…Les 8-hydroxyesters (5R)et (5s)-8 sont saponifies au moyen de KOH/EtOH. La lactonisation des 8-hydroxyacides bruts en (6R)et (6S)-9 est rtaliste dans MeCN en presence d'dmherlyst 15 (H') et de tamis moleculaire 4 A [9]. L'hydrogtnation dans l'hexane sur Pd/BaSO, empoisonnk par la…”