Bu4N[AuCl4]-Catalyzed Synthesis of Highly Substituted Furans from 2-(1-Alkynyl)-2-alken-1-ones in Ionic Liquids: An Air-Stable and Recyclable Catalytic System - Liu, Xueyuan; Pan, Zhenliang; Shu, Xingzhong; Duan, Xinhua; Liang, Yongmin (Synlett, 2006)