Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India.
J Org Chem. 2023 Apr 7;88(7):4519-4527. doi: 10.1021/acs.joc.2c03097. Epub 2023 Mar 29.
A convenient protocol for the synthesis of spirobenzofuran-isobenzofurans and substituted benzofurans via a modified Hauser-Kraus reaction of 3-sulfonylphthalide with 2-formylaryl triflates is reported here. The initial reaction involved 1,2-addition of phthalide to the formyl group and intramolecular cyclization via substitution of triflate followed by a cascade of rearrangements leading to spirolactone or benzofuran derivatives. The electronic nature of substituents on aryl triflates affected the course and outcome of the reaction. The mechanism was supported by successful characterization of one of the intermediates by mass spectrometry. A medicinally relevant influenza virus type B inhibitor, benzofuroisocoumarin, was synthesized in a single step from the spiro compound, thus demonstrating the synthetic utility of our methodology.
本文报道了通过 3-磺酰基邻苯二甲酰亚胺与 2-甲酰芳基三氟甲磺酸酯的改进豪泽-克劳斯反应，方便地合成螺苯并呋喃-异苯并呋喃和取代苯并呋喃的方法。初始反应涉及邻苯二甲酰亚胺对甲酰基的 1,2-加成以及通过三氟甲磺酸酯取代的分子内环化，随后是一系列重排反应，导致螺内酯或苯并呋喃衍生物。芳基三氟甲磺酸酯上取代基的电子性质影响反应的进程和结果。通过质谱成功表征了一种中间体，从而证实了该反应机理。从螺化合物一步合成了具有医学相关性的乙型流感病毒抑制剂苯并呋喃异香豆素，从而证明了我们方法的合成实用性。
