Cyanide-Free Synthesis of Air Stable N-Substituted Li and K Cyanamide Salts from Tetrazoles. Applications toward the Synthesis of Primary and Secondary Cyanamides as Precursors to Amidines
作者:Edouard Duchamp、Stephen Hanessian
DOI:10.1021/acs.orglett.0c03085
日期:2020.11.6
A practical two-step synthesis of N,N′-disubstituted cyanamides consists in the low-temperature metalation of N-substituted 5H-tetrazoles that undergo spontaneous cycloreversion at 0 °C releasing dinitrogen, and forming N-metalated cyanamides that can be reacted in situ with a variety of electrophiles. Remarkably, the N-substituted Li and K cyanamides are air stable white solids at room temperature
three-component reaction of cyanamides, amines, and diaryliodonium triflates was developed for the synthesis of guanidines. The mild reaction accommodates both aromatic and aliphatic amines and provides the products in good yields with good functional group tolerance. Moreover, it was demonstrated that C–H activation of the arenes could be realized for the direct preparation of guanidines.
作者:Antoine Nitelet、Johan Wouters、Damien F. Dewez、Gwilherm Evano
DOI:10.1021/acs.orglett.7b02859
日期:2017.12.1
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
protocol is established for the synthesis of disubstituted cyanamides through the transition-metal free N-arylation of cyanamides by diaryliodonium triflates in aqueous media. Both alkyl and arylcyanamides are well compatible with the mild reaction conditions. The one-pot synthesis of ureas is also possible through sequential arylation and hydrolysis of cyanamides, diaryliodonium triflates and H2O
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)