5(4H)-Oxazolones. Part X. Acid and base effects on the translactonization reaction of 4-(2-Oxa-alkylidene)-5(4H)-oxazolones: New synthesis of 5-alkylidene-3-benzoylamino-2(5H)-furanones
作者:Maria Luisa Gelmi、Francesca Clerici、Alessandra Melis
DOI:10.1016/s0040-4020(96)01101-5
日期:1997.2
4-(2-Oxa-alkylidene)-5(4H)-oxazolones (azlactones) 1 can be transformed in acidic conditions (anhydrous HBr/CHCl3) into 5-alkylidene-3-benzoylamino-2(5H)-furanones 2 which have Z configuration at the exocyclic double bond. The same reaction conducted in acetic acid as solvent gives, besides the alkylidene-furanones 2, the furanyl acetates 5. The result of azlactone transformation in the presence of
可以在酸性条件下(无水HBr / CHCl 3)将4-(2-Oxa-亚烷基)-5(4 H)-恶唑酮(azlactones)1转化为5-亚烷基3-苯甲酰基氨基-2(5 H)-呋喃酮在环外双键处具有Z构型的2。在乙酸中作为溶剂进行的相同反应,除了亚烷基-呋喃酮2以外,还产生了呋喃乙酸酯5。在碱(DBU)存在下氮杂内酯转化的结果取决于起始材料中的空间位阻。受阻越少的恶唑酮1a,b产生的缩合产物8越受阻的a唑酮1c生成呋喃酮2c或在烷基化剂存在下生成呋喃酮2d。