Synthesis of 2-(5H)-furanones by cyclization of alkyl allene carboxylates in triflic acid
作者:Oussama Abdelhamid Mammeri、Ilia M. Baranov、Alexandr Yu Ivanov、Irina A. Boyarskaya、Aleksander V. Vasilyev
DOI:10.1016/j.tet.2023.133649
日期:2023.10
(triflic acid, TfOH) at room temperature or 70 °C for 30 min are cyclized to form 2-(5H)-furanones in yields up to 83%. The reaction cationic intermediates, O-monoprotonated [R2(R3)C=C=C(R1)–C(=O+H)OAlk] and O,C-diprotonated [R2(R3)C+–CH=C(R1)–C(=O+H)OAlk] forms of starting allenes, have been studied experimentally by NMR and theoretically by DFT calculations. It has been found that the cyclization proceeds
烷基丙二烯羧酸盐 [R 2 (R 3 )C=C=C(R 1 )–C(=O)OAlk] 在 Brønsted 超强酸 CF 3 SO 3 H(三氟甲磺酸,TfOH)中,室温或 70 °C 30 min 环化形成 2-(5 H )-呋喃酮,产率高达 83%。反应阳离子中间体,O-单质子化 [R 2 (R 3 )C=C=C(R 1 )–C(=O + H)OAlk] 和 O,C-二质子化 [R 2 (R 3 )C + – CH=C(R 1 )–C(=O + H)Olk] 形式的起始丙二烯,已通过 NMR 进行了实验研究并在理论上通过 DFT 计算。已发现环化通过起始丙二烯的O,C-二质子化形式进行。