S1 Supporting Information Highly Selective Synthesis of 6-Substituted Benzothiophenes by Sc(OTf) 3 -Catalyzed Intermolecular Cyclization and Sulfur Migration Xiaoming Wang, Tobias Gensch, Frank Glorius* Table of content 1. General information………………………………………………………S2 2. Synthesis of N-(arylthio)succinimides………………………………....…S2 3. Sc(OTf)3-Catalyzed cyclization of N-(arylthio)succinimides with alkynes……..……………………………………………………..………S4 4. Preliminary mechanism studies……….......................................…….….S12 5. X-ray crystal structure analysis of compound 3a……………...…...…...S20 6. For details on the calculations………………………………….…….......S22 7. References………………………………………………………….……...S29 8. NMR spectra of the benzo[b]thiophenes………….….…………..……...S30 Electronic Supplementary Material (ESI) for Organic Chemistry Frontiers. This journal is © the Partner Organisations 2016