First total synthesis of the only known 2-isopropyliden-2H-benzofuran-3-one isolated from V. luetzelburgii
作者:Jorgelina L. Pergomet、Enrique L. Larghi、Teodoro S. Kaufman、Andrea B. J. Bracca
DOI:10.1039/c6ra28587b
日期:——
The first total synthesis of 5-(1-hydroxy-1-ethyl)-2-isopropyliden-2H-benzofuran-3-one, is reported in its racemic and in one of its optically active [(S)-(−)] forms. This heterocycle, isolated from Verbesina luetzelburgii, is the only known 2-isopropyliden-2H-benzofuran-3-one produced by species of Verbesina. The sequence took place in eight steps and 19% overall yield (up to 33% for the chiral form)
据报道,在其外消旋体和其中一种旋光性[(S)-(-)中,首次合成了5-(1-羟基-1-乙基)-2-异亚丙基-2 H-苯并呋喃-3-酮。] 形式。这种杂环是从Verbesina luetzelburgii分离而来的,是由Verbesina物种生产的唯一已知的2-isopropyliden-2 H -benzofuran -3-one 。该序列分八步进行,得自4'-羟基苯乙酮,总产率为19%(手性形式最高为33%)。它entailed羰基保护为1,3-二氧戊环和苯酚的邻位甲酰化,然后用氯丙酮进行威廉姆森醚化和有机催化的交叉羟醛缩合,得到2-乙酰基-2,3-二氢苯并呋喃-3-醇中间体。后者经过羰基部分的甲基格氏加成反应,然后对苄醇进行选择性氧化并脱保护,得到β-羟基二酮衍生物。MsCl辅助的叔醇脱水建立了异亚丙基基序,而合成则是通过化学或酶促(胡萝卜,芹菜酸)选择性还原外环羰基而达到的。