1: boron trifluoride diethyl etherate; 1,1,1,2,2,2-hexabutyl-distannane / acetonitrile / 2 h / 20 °C / UV-irradiation 2: triethyl borane; tri-n-butyl-tin hydride / hexane; acetonitrile / 2 h / 20 °C / Darkness View Scheme