1996 ketones

ketones (acyclic compounds)P 0200

16 - 100Reaction of β-Ethylthiopropionyl Tetrafluoroborates with Alkynes.Stereospecific One-Pot Synthesis of 1-Ethylthiopenta-1,4-dien-3-ones.— β-Ethylthiopropionyl tetrafluoroborate, in situ generated from the corre-sponding acyl fluoride (II) and gaseous BF3, reacts with alkynes (I) to form thehitherto unknown products (III) of a regio- and stereospecific syn-addition ofacryloyl and ethylthio groups to the triple bond. The reaction proceeds throughformation of six-membered cyclic sulfonium salts. Interestingly, treatmentof (IIIc) with perchloric acid results in recyclization to the cyclic sulfoniumstructure (IV). — (NENAJDENKO, V. G.; LEBEDEV, M. V.; BALENKOVA,E. S.; Synlett (1995) 11, 1133-1134; Dep. Chem., Lomonosov Moscow StateUniv., Moscow 119899, Russia; EN)

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