Pseudoesters and Derivatives. XXXI1. Synthesis of 5-Ethylthio-, 5-Ethylsulfinyl- and 5-Ethylsulfonylfuran-2(5H)-ones
摘要:
Convenient syntheses of 5-(ethylthio)furan-2(5H)-ones 2a-k from the appropriate 5-methoxyfuran-2(5H)-one 1a-g are described. The oxidation to the corresponding sulfoxides 5a-c and sulfones 6a-f is also reported.
Polycyclic Hydroxyquinones. Part 29. Regioselective Reactions of 5-sulphur-substituted furan-2(5H)-one anions with naphthoquinone monoketals. Application to the synthesis of anthracyclinone precursors
afford exclusively the C-5 substituted Michael adducts in good yield. The annelation reactions of the anions generated from furanones 30 and 33 with naphthoquinone monoketals 11 and 12 lead to 2-sulphur-substituted 1,4-anthraquinones 32, 35 and 36. Diels-Alder reaction of the 1,4-anthraquinones 41 and 42 with (E)-1,3-bis[(trimethylsilyl)oxy]buta-1,3-diene (37) affords ABCD tetracyclic systems related