A novel phosgene-free route to different isocyanates starts from CO 2 and aminosilanes (cf. silylamines) to form so-called carbamoyloxysilanes (O-silylcarbamates), i. e., compounds with the general motif R 1 R 2 NÀ COÀ OÀ SiR 3 R 4 R 5 as potential precursors. We focused on the insertion reaction of CO 2 into SiÀ N bonds of substrates with cyclic (mostly aromatic) amine substituents, i. e.