摘要:
Silver-phosphine complexes can be utilized as highly efficient catalysts for the cyclization of 2-(1-hydroxy-3-arylprop-2-ynyl)phenols (1) to give product 2, key intermediates to synthesize aurones (4), with good yields and stereoselectivities in water-toluene mixed solvent. With fluoride as the counteranion, complete E- or Z-stereoselectivities were achieved at high temperature or room temperature, respectively. Furthermore, after removing water from the reaction mixtures, the toluene solution containing crude products 2 can be treated by MnO2 directly without further purification, to give aurones 4 in good yields.