diastereoselectivity of the [4+2] cycloadditions: the number of fluorine atoms attached to the double bond and the number and the bulkiness of alkyl substituents at the 5-position of the furan-2(5H)-onesystem. The monofluorinated furan-2(5H)-one 1 was generally more reactive than the difluorinated furan-2(5H)-ones 2–4. While the reactions of the furan-2(5H)-ones 2–4 with isobenzofuran exclusively
A novel rearrangement induced by the addition of organyllithium reagents to 2,3-difluoro-4,4-dimethylbut-2-enolide
作者:Oldrich Paleta、Andrew Pelter、Josef Kebrle
DOI:10.1016/0040-4039(94)88482-x
日期:1994.12
Addition of O-nucleophiles and Grignard reagents in the presence of copper(I) bromide-dimethyl sulphide to 2,3-difluoro-4,4-dimethylbut-2-enolide proceeds by 1,4-addition and expulsion of a fluoride anion to give 4-substituted butenolides. Organolithium reagents, however, react to give furan(2H)-3-ones in a novel oxygen rearrangement reaction.
New fluorinated nucleoside analogues with 2-butenolide rings prepared by nucleophilic vinylic fluorine displacement in 4,4-dialkyl-2,3-difluorobut-2-en-4-olides
作者:Oldřich Paleta、Zdeněk Duda、Antonín Holý
DOI:10.1070/mc2001v011n01abeh001377
日期:——
Fluorine-Containing Butanolides and Butenolides. Vinylic Fluorine Displacement in 4,4-Dialkyl-2,3-difluoro-2-buten-4-olides and a Novel Rearrangement Induced by Organolithium Addition to a Carbonyl Group
3-substituted derivatives (4–24). Softer Grignard reagents in the form of a copper (I) bromide-dimethyl sulfide complex reacted in the same way as O-nucleophiles to afford 3-alkyl- or 3-aryl derivatives (25–26). Harder organolithium reagents attacked the carbonyl group to give unstable hydroxy compounds that rearranged spontaneously to furan(2H)-3-ones (27–29) in a novel oxygen rearrangement reaction.