Fluorinated butanolides and butenolides. Part 5. Synthesis and nucleophilic reactions of 3-chloro-2-fluoro-2-buten-4-olide as tetronic acid analogue. Conjugate addition of hard nucleophiles and vinylic halogen displacement with soft phosphorus nucleophiles
作者:Oldřich Paleta、Andrei Volkov、Jiřı́ Hetflejš
DOI:10.1016/s0022-1139(99)00235-3
日期:2000.3
addition to 1-bromo-1,2,3,4-tetrachloro-1,2-difluorobutane (10). Fuming sulfuric acid affected CH2–Br bond in 6a to afford 4-bromo-3,4-dichloro-3,4-difluorobutan-1-ol (8), while with 10 bearing stable terminal CH2–Cl group the reaction took place at the trihalomethyl group to give 2,3,4-trichloro-2-fluorobutanoic acid (11a). Its sodium salt (11b) cyclized in solution or thermally in the solid state
从1,2-二溴-1开始,通过六步合成法制备了3-氯-2-氟丁-2-烯-4-酸酐(13)和2-氟丁-2-烯-4-酸酐(14), 2-二氯-1,2-二氟乙烷(5)。紫外线引发的向乙烯中添加5,得到1,4-二溴-1,2-二氯-1,2-二氟丁烷(6a),很容易将其脱氯化氢成4-溴-3,4-二氯-3,4-二氟丁- 1-烯(7),然后通过氯加成1-溴-1,2,3,4-四氯-1,2-二氟丁烷(10)。发烟硫酸在6a中影响CH 2 -Br键,得到4-溴-3,4-二氯-3,4-二氟丁烷-1-醇(8),而与10带有稳定的CH 2 -Cl端基的反应在三卤甲基上发生,得到2,3,4-三氯-2-氟丁酸(11a)。它的钠盐(11b)在溶液中或以固态形式热循环成2,3-二氯-2-氟丁丹-4-油酸酯(12),然后用叔胺脱氯化氢得到新的丁烯内酯13或用2-氟丁酸二氯脱氯-2-烯-4-丙交酯(14)。硬亲核试剂(如甲醇和哌啶