The invention relates to methods for CC bond formation using organolithium compounds under continuous flow conditions in a micro or mesoreactor system, wherein an organic substrate is reacted with an alkyl lithium compound in the presence of a donor solvent to form a Li intermediate, which can be reacted in situ or subsequently in a second reaction step with an electrophile to form an organic secondary product, the organolithium compound RLi being used as a solution in a hydrocarbon or hydrocarbon mixture and the RLi concentration being at least 3 M, preferably at least 4 M.