Synthesis of new 2-substituted 2,5-dihydrofuranone derivatives and their chemical transformations

摘要: 2,5-Dihydrofuran-2-ones having functional substituents in the 3-position constitute structural fragments of many natural and synthetic biologically active compounds [1–5]. One most general convenient methods synthesis functionally substituted furan2(5H)-ones is based on reactions α-hydroxy ketones with containing an activated methylene group [6–8]. In continuation our studies this field, present communication we report chemical transformations a new class compounds, 2,5-dihydrofuran-2-imines readily accessible ketones. We found that, contrary to published data [9], tertiary react malononitrile give mixtures corresponding I products their subsequent reaction second molecule, 2-(2,5-dihydrofuran-2-ylidene)malononitriles II, which were formed good yields. Detailed examination view find optimal conditions showed that process occurs even absence catalyst upon mixing reactants alcohol or benzene. General procedures for malononitrile. a. The ketone malononitrile, 50 mmol each, added solution 0.115 g (5 mmol) metallic sodium 25 ml anhydrous ethanol. mixture was kept 15–20 h at room temperature, solvent distilled off under reduced pressure, residue dissolved benzene, precipitate filtered recrystallized from ethanol–water (2 : 1) isolate compound IIa IIb. benzene diluted four volumes hexane, heptane. thus isolated Ia Ib. b. A ethanol temperature. then treated as described above c. partially