Metal-involving generation of aminoheterocycles from N-substituted cyanamides: Toward sustainable chemistry (a Minireview)

Copper-Catalyzed, Ligand-Controlled N(sp3)- or N(sp)-Selective Arylation of Cyanamides

Cyanamides possess both nucleophilic and electrophilic centers, and their arylation reactions are known to proceed at N(sp3) and C(sp) sites, leading to N-aryl cyanamides or amidines. N(sp) selectivity has also been reported only in the presence of amines, thus leading to guanidines. Herein, we report a general copper-catalyzed ligand-controlled Chan-Lam-Evans arylation of cyanamides proceeding regioselectively at the N(sp3) or N(sp) atoms and leading to either N-aryl cyanamides or dissymmetric carbodiimides. The nature of the ligand, either a bipyridine or a diamine, controls the product distribution and thus offers a divergent entry to useful building blocks from readily available cyanamides.

Copper(II) Prevents the Saccarine-Dialkylcyanamide Coupling by Forming Mononuclear (Saccharinate)(Dialkylcyanamide)copper(II) Complexes

The reaction in the system CuII/sacNa(H)/NCNR2 (sacNa(H) = sodium saccharinate (saccharin); R = Me, Et) results in the formation of the complexes [Cu(sac)2(NCNR2)(H2O)2] (R = Me 1, Et 2) instead of the expected products derived from the saccharin–cyanamide coupling. Complexes 1, 2, and hydrate 1·2H2O were characterized by IR, AAS (Cu%), TGA, and also by single-crystal X-ray diffraction for 1 and 1·2H2O. An integrated computational study of model structure 1 in the gas phase demonstrates that the Cu–Ncyanamide and Cu–Nsac coordination bonds exhibited a single bond character, polarized toward the N atom and almost purely electrostatic, with the calculated vertical total energies for the Cu–Ncyanamide and Cu–Nsac of 43.6 and 156.4 kcal/mol, respectively. These data confirmed that the copper(II) completely blocks the nucleophilic centers of ligands via coordination, thus preventing the saccharin–cyanamide coupling.

Copper-Catalyzed Alkenylation of Cyanamides

An efficient procedure for the copper-catalyzed cross-coupling between a broad range of cyanamides and iodoalkenes is reported. Upon reaction with catalytic amounts of copper(I) iodide and 2,2'-bisimidazole in the presence of cesium carbonate in DMF at 80 °C, a fast, regioselective, and stereoretentive cross-coupling occurs. This reaction, which was found to have a broad substrate scope, provides the first general entry to N-alkenylcyanamides, building blocks that hold great synthetic potential.

A novel family of homoleptic copper(i) complexes featuring disubstituted cyanamides: a combined synthetic, structural, and theoretical study

Homoleptic copper(i) complexes featuring disubstituted cyanamides were obtained and characterized using experimental methods and their properties were studied theoretically.