In situ <i>Grignard</i> Metalation Method, Part II: Scope of the One‐Pot Synthesis of Organocalcium Compounds

Abstract

Abstract The in situ Grignard Metalation Method ( i GMM) is a straightforward one‐pot strategy to synthesize alkaline‐earth metal amides in multi‐gram scale with high yields via addition of bromoethane to an ethereal suspension of a primary or secondary amine and magnesium (Part I) or calcium (Part II). This method is highly advantageous because no activation of calcium is required prior to the reaction. Contrary to the magnesium‐based i GMM, there are some limitations, the most conspicuous one is the large influence of steric factors. The preparation of Ca(hmds) 2 succeeds smoothly within a few hours with excellent yields opening the opportunity to prepare large amounts of this reagent. Side reactions and transfer of the i GMM to substituted anilines and N‐heterocycles as well as other H‐acidic substrates such as cyclopentadienes are studied. Bulky amidines cannot be converted directly to calcium amidinates via the i GMM but stoichiometric calciation with Ca(hmds) 2 enables their preparation.