A Recyclable Palladium-Catalyzed Synthesis of 2-Methylene-2,3-Dihydrobenzofuran-3-ols by Cycloisomerization of 2-(1-Hydroxyprop-2-ynyl)phenols in Ionic Liquids
A Recyclable Palladium-Catalyzed Synthesis of 2-Methylene-2,3-Dihydrobenzofuran-3-ols by Cycloisomerization of 2-(1-Hydroxyprop-2-ynyl)phenols in Ionic Liquids
Acid-Catalysed or Radical-Promoted Allylic Substitution of 2-Methylene-2,3-dihydrobenzofuran-3-ols with Thiol Derivatives: a Novel and Expedient Synthesis of 2-(Thiomethyl)benzofurans
The 2-thiomethylbenzofuran derivatives 3 are conveniently prepared in good yields through the reactions between the readily available 2-methylene-2,3-dihydrobenzofuran-3-ols 1 and the thiolderivatives 2 (including alkyl thiols, thiophenol, and thioacetic acid). The allylicsubstitution process may be either acid-catalysed or promoted by radical initiators. In the first case, the reactions are carried
通过易得的2-亚甲基-2,3-二氢苯并呋喃-3-醇1和硫醇衍生物2(包括烷基硫醇、苯硫酚和硫代乙酸)之间的反应,可以方便地以良好的产率制备2-硫甲基苯并呋喃衍生物3。烯丙基取代过程可以由酸催化或由自由基引发剂促进。在第一种情况下,反应在作为质子源的 H 2 SO 4 存在下,在 1,2-二甲氧基乙烷 (DME) 作为溶剂中,在 90 °C 下进行。在偶氮双(异丁腈)(AIBN)或过氧化苯甲酰(BP)作为自由基引发剂的存在下,自由基促进反应发生在 90 °C 的 DME 中。
A Novel Synthesis of 2-Functionalized Benzofurans by Palladium-Catalyzed Cycloisomerization of 2-(1-Hydroxyprop-2-ynyl)phenols Followed by Acid-Catalyzed Allylic Isomerization or Allylic Nucleophilic Substitution
furans 3 and 2-alkoxymethylbenzofurans 4-6, based on palladium-catalyzed cycloisomerization of 2-(1-hydroxyprop-2-ynyl)phenols 1 under basic conditions to give 2-methylene-2,3-dihydrobenzofuran-3-ols 2, followed by acid-catalyzed isomerization or allylic nucleophilic substitution with alcohols as nucleophiles, is reported. Cycloisomerization reactions leading to 2 (80-98% yields) were carried out at
A Recyclable Palladium-Catalyzed Synthesis of 2-Methylene-2,3-Dihydrobenzofuran-3-ols by Cycloisomerization of 2-(1-Hydroxyprop-2-ynyl)phenols in Ionic Liquids
作者:Raffaella Mancuso、Bartolo Gabriele
DOI:10.3390/molecules180910901
日期:——
A recyclable palladium-catalyzed synthesis of 2-methylene-2,3-dihydrobenzofuran-3-ols 2 by heterocyclization of 2-(1-hydroxyprop-2-ynyl)phenols 1 in an ionic liquid medium (BmimBF4) is presented. The process takes place under relatively mild conditions (100 °C, 5 h) in the presence of catalytic amounts (2 mol %) of PdI2 in conjunction with KI (5 equiv with respect to PdI2) and an organic base, such as morpholine (1 equiv with respect to 1), to give 2 in high yields (70%–86%). The PdI2-KI catalytic system could be recycled up to six times without appreciable loss of activity. Moreover, products 2 could be easily converted in a one-pot fashion into 2-hydroxymethylbenzofurans 3 (52%–71%, based on 1) and 2-methoxymethylbenzofurans 4 (52%–80%, based on 1) by acid-catalyzed allylic isomerization or allylic nucleophilic substitution.