The behavior of the furanones 1–4 towards nitrileoxides 5–7 has been investigated, in particular with respect to the regio- and stereoselectivity. Cycloaddition of benzonitrile oxide (5) to 4,5-diethylsulphonylfuran-2(5H)-one (12) leads as sole addition product to the isoxazoline 30, that was easily aromatized to the isoxazole derivative 31, which is a useful synthon for the preparation of heteroanthracyclinone
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
Pseudoesters and Derivatives. Part 38. 1,3-Dipolar Cycloadditions of Aryl Azides and an Aziridine, via Azomethine Ylide, to 2(5H)-Furanones Substituted at the 5-Position by Methoxy and Sulfur Bearing Group
作者:M. Carmen Paredes、Gemma Gonzalez、M. Victoria Martín
DOI:10.3987/com-99-s15
日期:——
Pseudoesters and Derivatives. XXXI<sup>1</sup>. Synthesis of 5-Ethylthio-, 5-Ethylsulfinyl- and 5-Ethylsulfonylfuran-2(5<i>H</i>)-ones
作者:Francisco Fariña、M. Victoria Martín、Rosa M. Martín-Aranda、Ana Martínez de Guereñu
DOI:10.1080/00397919308009801
日期:1993.2
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.
Pseudoesters and derivatives. 29. Regioselective reactions of the 5-(ethylthio)furan-2(5H)-one anion with electrophiles