Reactions of β-fluorovinamidinium salt with activated methylene compounds
摘要:
beta-Fluoro vinamidinium salt (1) reacted with 1.1 equiv. of methylene compounds activated with carbonyl or cyano groups in the presence of lithium diisopropylamide or sodium hydride and triethylamine in tetrahydrofuran at room temperature to give monofluorinated multifunctional dienaminones (3) and dienaminonitriles (5) in moderate to good yields. The reactions of 1 with 2.2 equiv. of enolates derived from beta-keto esters at 80 degrees C gave the cyclization products, fluorinated isophthalates (6) in good yields, while a similar reaction with 2.2 equiv. of cyanoacetate and malononitrile produced the non-cyclic 1,3-dienecarbonitriles (7) in excellent yields. (C) 1998 Elsevier Science Ltd. All rights reserved.