*3.1. General Information*

All reactions were performed under an argon atmosphere with dry solvents, unless otherwise stated. Dry tetrahydrofuran (THF) and methylene chloride (CH2Cl2) were obtained from Ultimate Solvent Purification System (JC Meyer Solvent System, Laguna Beach, CA, USA). Other dry solvents were purchased as anhydrous grade. All glassware is oven-dried and/or flame-dried before use. All commercially available reagents were purchased and used without further purification. Reactions were monitored by thin-layer chromatography (TLC) on silica gel plates (Merck TLC Silica Gel 60 F254, Darmstadt, Germany) using UV light, PMA (an ethanolic solution of phosphomolybdic acid) or ANIS (an ethanolic solution of para-anisaldehyde) as visualizing agent. Purification of products was conducted by column chromatography through silica gel 60 (0.060−0.200 mm). Melting points of all solid compounds were determined by Buchi M-565. NMR spectra were obtained on Bruker AVANCE III 500 MHz (Bruker Corporation, Billerica, MA, USA) at 20 ◦C using residual undeuterated solvent or TMS (tetramethylsilane) as an internal reference. High-resolution mass spectra (HR-MS) were recorded on a JEOL JMS-700 (JEOL, Tokyo, Japan) using EI (electron impact).

#### *3.2. General Procedure of Ti(Oi Pr)4/pyridine Mediated Knoevenagel Condensation* (**4, 5a-e**)

To a stirred solution of 1-methyl-2-oxindole (**1**) (1.0 mmol) and the corresponding acetophenone or chalcone (**2**) (1.0 mmol, 1.0 equiv.) in THF (10 mL) were added pyridine (0.17 mL, 2.0 mmol, 2.0 equiv.) and Ti(O*<sup>i</sup>* Pr)4 (0.90 mL, 3.0 mmol, 3.0 equiv.). The reaction mixture was stirred at rt for 24 h, Then, the mixture was diluted with EtOAc (100 mL) and 1 N aq. HCl solution (30 mL). The organic layer was separated and washed with sat. aq. NaHCO3 (30 mL) and brine (30 mL). The remained organic layer was dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude residue was purified by column chromatography to afford Knoevenagel product **5** or 1,4-addition adduct **4**.
