Hu Yimin, Hu Yadong, Hu Qiong, Ma Jie, Lv Shuang, Liu Baohua, Wang Shaowu
Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Key Laboratory of Functional Molecular-Based Materials, Institute of Organic Chemistry, School of Chemistry and Materials Science, Anhui Normal University, Wuhu, Anhui, 241000, P. R. China.
Chemistry. 2017 Mar 23;23(17):4065-4072. doi: 10.1002/chem.201605785. Epub 2017 Feb 6.
A facile method for the synthesis of fused, multifunctionalized salicylaldehydes and salicylketones by a one-pot, three-step cascade hexadehydro-Diels-Alder (HDDA) reaction of tetraynes followed by an intermolecular aldehyde/ketone reaction and hydroxylation is reported. Target compounds were prepared by the condensation of malonates with 3-bromo-1-propyne, and the resulting 2,2-di(1-propyn-3-yl)malonates underwent cross-coupling with phenylethynyl bromides to afford 2,2-di(5-phenyl-2,4-pentadiynyl)malonates, which underwent intramolecular cyclization to produce bicyclic salicylaldehydes. The overall transformation involves the formation of four new C-C bonds and one new C -O bond through both intramolecular and intermolecular reactions. The reaction is easy to perform, proceeds under mild conditions, and exhibits excellent regioselectivity. Water, a simple and readily available reagent, was employed as the OH source. A plausible reaction mechanism is proposed for this new annulation based on isotopic substitution experiments.
报道了一种简便的方法，通过四炔的一锅三步串联六脱氢狄尔斯-阿尔德（HDDA）反应，随后进行分子间醛/酮反应和羟基化反应，合成稠合的、多官能化的水杨醛和水杨酮。目标化合物通过丙二酸酯与3-溴-1-丙炔缩合制备，所得的2,2-二（1-丙炔-3-基）丙二酸酯与苯乙炔基溴进行交叉偶联，得到2,2-二（5-苯基-2,4-戊二炔基）丙二酸酯，其进行分子内环化生成双环水杨醛。整个转化过程通过分子内和分子间反应形成四个新的C-C键和一个新的C-O键。该反应易于进行，在温和条件下进行，并表现出优异的区域选择性。水，一种简单且易于获得的试剂，被用作OH源。基于同位素取代实验，为这种新的环化反应提出了一个合理的反应机理。
