All cross coupling reactions were carried out in oven-dried Schlenk glassware using septa and syringes under nitrogen or argon atmosphere. THF and 1,4-dioxane were dried using MBraun system MB-SPS-800, and triethylamine was refluxed under argon atmosphere over ketyl sodium, distilled and stored in a Schlenk flask over potassium hydroxide pellets under argon atmosphere. Dry methanol was purchased from Sigma-Aldrich Chemie GmbH. 4,4,5,5-Tetramethyl-1,3,2-dioxaborolane (pinacolborane) was

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... from Sigma-Aldrich Chemie GmbH and used as supplied. Tetrakis(triphenylphosphane)palladium(0) and cesium carbonate were purchased from Merck Serono KGaA. Commercial grade reagents were used as supplied without further purification and were purchased from Acros Organics, Compounds 1h-1i, 1k-1n and 3a-3q are commercially available (see Table 1 ). Compounds 1a-1c, [1] 1d-1g [2] and 1j [3] were prepared according to the literature procedures. The purification of products was performed on silica gel 60 (0.015-0.040 mm) from Merck Serono KGaA Darmstadt using flash technique and under pressure of 2 bar. The crude mixtures were adsorbed on Celite ® 545 (0.02-0.10 mm) from Merck Serono KGaA Darmstadt before chromatographic purification. The reaction progress was monitored qualitatively using TLC Silica gel 60 F 254 5 x 7.5 cm aluminium sheets obtained by Merck Serono KGaA Darmstadt. The spots were detected with UV light at 254 nm and using aqueous potassium permanganate solution. Supplementary Material (ESI) A solution of iodine (25.7 g, 101 mmol) in 180 mL DMF was dropped to the solution of 7-azaindole (12.1 g, 100 mmol) and potassium hydroxide (16.5 g, 250 mmol) in 180 mL DMF at room temperature and the mixture was stirred for 45 min. The reaction mixture was then poored on 1 L ice water containing 1 % ammonia and 0.2 % sodium disulfite. The precipitate was filtered, washed with ice water and dried in vacuo to obtain 23.7 g (97.2 mmol, 97 % yield) of a yellow solid. The obtained solid was used without further purification for the next step. It was suspended in 180 mL dichloromethane, 4-dimethylaminopyridine (1.21 g, 9.72 mmol) was added and di-tert-butyl dicarbonate (32.8 g, 146 mmol), dissolved in 180 mL dichloromethane, was added dropwise for 30 min. The mixture was stirred for 30 min. at room temperature, washed with 200 mL 0.1 N HCl, and the aqueous phase was extracted with dichloromethane (2 x 100 mL). The combined organic layers were dried with sodium sulphate, the solvents were removed under reduced pressure and the residue was adsorbed onto Celite ® and purified chromatographically on silica gel with petroleum ether (boiling range 40-60 °C)/ethyl acetate (PE-EtOAc = 5:1, R f (PE-EtOAc = 20:1): 0.14) to give 31.6 g (91.8 mmol, 94 % yield; 92 % total yield over two