Synthesis of Spiroketals by Synergistic Gold and Scandium Catalysis

An ultrafast synthesis of spiroketals by synergistic gold­(I) and Sc­(III) catalysis has been reported. Diverse 5,6-benzannulated spiroketals were rapidly constructed by the diastereoselective [4 + 2] cycloaddition between gold-generated enol ether and Sc­(III)-catalyzed o-quinone methide intermediates. Ultrafast reaction rate, ambient reaction temperature, general scope, high yields, excellent diastereoselectivity, and good scalability are attractive features of this method.本研究报道了一种通过一价金（gold(I)）与三价钪（Sc(III)）协同催化实现螺环缩酮（spiroketals）超快合成的方法。通过金催化生成的烯醇醚（enol ether）与三价钪催化生成的邻醌甲基化物（o-quinone methide）中间体之间的非对映选择性[4+2]环加成反应，可快速构建多种5,6-苯并稠合螺环缩酮类化合物。该方法具有反应速率超快、常温反应、底物适用范围广、产物收率高、非对映选择性优异以及可放大性良好等突出优势。