A highly reactive form of calcium was prepared by the reduction of Ca (I1) salts with preformed lithium biphenylide. Remarkably, this activated calcium undergoes oxidative addition to organic bromides, chlorides, or even fluorides to form the organocalcium reagents under very mild conditions in high yields. The resulting organocalcium compounds undergo Grignard-type reactions. Transmetalation with Cu (1) salts forms calcium cuprate ...