S-1 Supporting Information for: Pyridine Activation via Copper(I)-Catalyzed Annulation toward Indolizines José Barluenga,* Giacomo Lonzi, Lorena Riesgo, Luis A. López, and Miguel Tomás* Instituto Universitario de Química Organometálica “Enrique Moles”, Unidad Asociada al CSIC, Universidad de Oviedo, Julián Clavería 8, 33071 Oviedo, Spain barluenga@uniovi.es ; mtl@uniovi.es General Methods: 1 H NMR and 13 C NMR spectra were recorded at room temperature in CDCl 3 , on a Bruker AC-300 (300 and 75.5 MHz), a Bruker AMX-400 (400 and 100 MHz) or a Bruker AV-600 spectrometers. Chemical shifts are given in ppm relative to TMS ( 1 H, 0.0 ppm) or CDCl 3 ( 13 C, 77.0 ppm). Carbon multiplicities were assigned by DEPT techniques. High-resolution mass spectra (HRMS) were determined by Universidad de Oviedo, Universidad de Burgos and Universidad de Vigo (CACTI) with a Finnigan Mat95 and a VG AutoSpec M Mass Spectrometers respectively. TLC was performed on aluminum-backed plates with silica gel 60 with F 254 indicator. All reactions were carried out under nitrogen using standard Schlenck techniques. CH 2 Cl 2 was distilled from CaH 2 . Flash column chromatography was carried out on silica gel (230-240 mesh). This study was carried out using pyridine derivatives 1a-v and vinyldiazoacetates 2a-d (Figure 1). Vinyldiazoacetates were prepared according to literature procedures. 1 4-