Regiospecific Synthesis of 3,4-Dihydrocoumarins via Substrate-Controlled [1,3]- or [3,3]-Sigmatropic Rearrangement - Xu, Xiangsheng; Li, Xiaoqing; Yan, Xinhuan; Wang, Hanshen; Deng, Yun; Shao, Jiangbin (Synlett, 2011)