One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger?aza-Wittig reaction

DIEGO CARNAROGLIO; KATIA MARTINA; GIOVANNI PALMISANO; ANDREA PENONI; CLAUDIA DOMINI; GIANCARLO CRAVOTTO

BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY

BEILSTEIN-INSTITUT

Lugar: Frankfurt; Año: 2013 vol. 9 p. 2378 - 2386

1860-5397

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.