1837-73-6Relevant articles and documents
Benzylic C-H isocyanation/amine coupling sequence enabling high-throughput synthesis of pharmaceutically relevant ureas
Krska, Shane W.,Lin, Shishi,Nkulu, Leah E.,Stahl, Shannon S.,Suh, Sung-Eun
, p. 10380 - 10387 (2021/08/12)
C(sp3)-H functionalization methods provide an ideal synthetic platform for medicinal chemistry; however, such methods are often constrained by practical limitations. The present study outlines a C(sp3)-H isocyanation protocol that enables the synthesis of diverse, pharmaceutically relevant benzylic ureas in high-throughput format. The operationally simple C-H isocyanation method shows high site selectivity and good functional group tolerance, and uses commercially available catalyst components and reagents [CuOAc, 2,2′-bis(oxazoline) ligand, (trimethylsilyl)isocyanate, andN-fluorobenzenesulfonimide]. The isocyanate products may be used without isolation or purification in a subsequent coupling step with primary and secondary amines to afford hundreds of diverse ureas. These results provide a template for implementation of C-H functionalization/cross-coupling in drug discovery.
One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger-aza-Wittig reaction
Carnaroglio, Diego,Martina, Katia,Palmisano, Giovanni,Penoni, Andrea,Domini, Claudia,Cravotto, Giancarlo
supporting information, p. 2378 - 2386 (2014/01/06)
A fast and efficient protocol for the synthesis of N,N'-disubstituted urea derivatives from alkyl halides and primary or secondary amines has been developed. The synthetic pathway combines nucleophilic substitutions and a Staudinger-aza-Wittig reaction in the presence of polymer-bound diphenylphosphine under 14 bar of CO2 pressure and has been performed in a one-pot two-step process. The protocol has been optimized under microwave irradiation and the scale-up experiment has been conducted under conventional conditions in a Parr reactor. The final compounds were isolated after simple filtration in almost quantitative overall yields which makes this procedure facile and rapid to execute.
N-methylimidazole-catalyzed synthesis of carbamates from hydroxamic acids via the lossen rearrangement
Yoganathan, Sabesan,Miller, Scott J.
, p. 602 - 605 (2013/04/11)
An efficient, one-pot, N-methylimidazole (NMI) accelerated synthesis of aromatic and aliphatic carbamates via the Lossen rearrangement is reported. NMI is a catalyst for the conversion of isocyanate intermediates to the carbamates. Moreover, the utility of arylsulfonyl chloride in combination with NMI minimizes the formation of often-observed hydroxamate-isocyanate dimers during the sequence. Under the present conditions, lowering of temperatures is also possible, enabling a mild protocol.
