3.1.1. General Procedure

All the reactions were carried out in a round-bottomed flask with an appropriate number of necks and side arms connected to a three-way stopcock and/or a rubber septum cap under an argon atmosphere. All vessels were first evacuated by rotary pump and then flushed with argon prior to use. Solutions and solvents were introduced by hypodermic syringe through a rubber septum. During the reaction, the vessel was kept under a positive pressure of argon. Dry THF was freshly prepared by distillation from benzophenone ketyl before use. Anhydrous CH2Cl2, DMF, ethanol, MeCN, methanol, pyridine, and toluene were purchased from Kanto Chemical Co. Inc. Infrared (IR) spectra were recorded on a JASCO FT/IR-4100 spectrophotometer using a 5 mm KBr plate. Wavelengths of maximum absorbance are quoted in cm−1. 1H-NMR spectra were recorded on a JEOL ECA–400 (400 MHz), Bruker AV-400N (400 MHz), and Bruker AV–500 (500 MHz) in CDCl3. Chemical shifts are reported in parts per million (ppm), and signals are expressed as singlet (s), doublet (d), triplet (t), multiplet (m), broad (br), and overlapped. 13C-NMR spectra were recorded on a JEOL ECA–400 (100 MHz), Bruker AV–400N (100 MHz), and Bruker AV–500 (125 MHz) in CDCl3. Chemical shifts are reported in parts per million (ppm) (see Supplementary Materials). High resolution mass (HRMS) spectra were recorded on a Thermo Scientific Exactive. All melting points were measured with a Yanaco MP-500D. Analytical thin layer chromatography (TLC) was performed using 0.25 mm E. Merck Silica gel (60F-254) plates. Reaction components were visualized phosphomolybdic acid or ninhydrin or *p*-anisaldehyde in 10% sulfuric acid in ethanol. Kanto Chem. Co. Silica Gel 60N (particle size 0.040–0.050 mm) was used for column chromatography.
