For quantitative flash chromatography, distilled technical grade solvents were used. THF, Et2O, toluene, hexane and CH2Cl2 were dried by passage over activated alumina under nitrogen atmosphere (H2O content < 7 ppm, Karl-Fischer titration). All chemicals were purchased and used as received unless stated otherwise. Chromatographic purification was performed as flash chromatography using Macherey-Nagel silica 40-63, 60 Å, using the solvents indicated as eluent with 0.1-0.5 bar pressure.