New chemoselective metalating agents for solid-phase synthesis

Development of new soluble, chemoselective metalating reagents is essential for exploring solid-phase organometallic chemistry. Cuprates and zincates were expected to be potentially usable for solid-phase chemistry, and we started to investigate chemoselective solid-phase halogen-metal exchange reactions using ate complexes. At 0°C, the 1alogen-zinc exchange reactions proceeded smoothly in the presence of 2.2 equiv of LTBZ, and the subsequent reaction with an electrophile followed by cleavage with NaOMe/MeOH-THF gave the desired product in an excellent yield. The immobilized organozincate on polymer support was also transformed into the immobilized organocuprate by treatment with lithium cyanothienylcuprate. The palladium-catalyzed cross-coupling reaction of the immobilized organozincate with iodobenzene proceeded smoothly at room temperature to give an unsymmetrical biaryl. This methodology is considered to provide a new chemoselective method for solid-phase carbon-carbon bond formation.