Manganese(II) Sulfate Powder is an Efficient Catalyst for the Synthesis of Coumarins from <i>In Situ</i> Generated Stabilized Phosphorus Ylides in Solvent-Free Conditions
reactive 1:1 intermediates, produced in the reactionbetweentriphenylphosphine and dialkyl acetylenedicarboxylates, by phenols (1-hydroxynaphthalene, 2-hydroxynaphthalene, and 4-bromophenol) leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitutionreaction with conjugate base to produce corresponding stabilized phosphorus ylides. Manganese(II) sulfate powder was found
摘要 三苯基膦与二烷基乙炔二羧酸酯反应产生的高反应性 1:1 中间体,由苯酚(1-羟基萘、2-羟基萘和 4-溴苯酚)质子化生成乙烯基三苯基鏻盐,与共轭物发生芳香族亲电取代反应。生成相应的稳定磷叶立德。发现硫酸锰 (II) 粉末可在 90°C 的无溶剂条件下催化稳定的磷叶立德转化为香豆素,原因是 1 小时的高转化率。还发现在无溶剂条件下,在无溶剂条件下,在硫酸锰 (II) 粉末存在下,微波可在 1 分钟内以 1 KW 的微波功率催化相同的反应。
Silica Gel Catalyzed Conversion of Dialkyl 2-(2-Hydroxy-1-naphthyl)-3-(1,1,1-triphenyl-λ 5 -phosphanylidene) Succinates to Alkyl 3-Oxo-3 H -benzo[ f ]chromene-1-carboxylates in Solvent-free Conditions
作者:Ali Ramazani、Ali Souldozi
DOI:10.1080/10426500307901
日期:2003.6
Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by 2-hydroxynaphthalene leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with conjugate base to produce dialkyl 2-(1-hydroxy-2-naphthyl)-3-(1,1,1-triphenyl-lambda(5)-phosphanylidene) succinates. Silica gel was found to catalyze conversion of dialkyl 2-(1-hydroxy-2-naphthyl)-3-(1,1,1-triphenyl-lambda(5)-phosphanylidene) succinates to alkyl 3-oxo-3H-benzo[f]chromene-1-carboxylates in solvent-free conditions at 60degreesC in fairly good yields.