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Synthesis of ureas from titanium imido complexes using CO2 as a C-1 reagent at ambient temperature and pressure.

Anderson, JC; Moreno, RB; (2012) Synthesis of ureas from titanium imido complexes using CO2 as a C-1 reagent at ambient temperature and pressure. Org Biomol Chem , 10 (7) 1334 - 1338. 10.1039/c1ob06576a.

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Abstract

The coordinatively unsaturated 12-electron complex dichloro t-butylimido bispyridine titanium(IV) (2a) has been shown to react with CO(2) to give N,N-bis-t-butyl urea. Two analogous sterically hindered coordinatively saturated 14-electron complexes dichloro t-butylimido trispyridine titanium(IV) (10a) and dichloro 2,6-(i-Pr)(2)phenylimido trispyridine titanium(IV) (10b) also gave their corresponding symmetrical ureas upon treatment with CO(2). Further experiments support the intermediary of metallocycles formed from heterocumulene metathesis reactions. The unsymmetrical urea N-benzyl, N-t-butyl urea (11) was produced from treatment of 2,6-(i-Pr)(2)phenylimido trispyridine titanium(IV) (10b) with CO(2) and interception with BnNH(2). Equimolar quantities of N,N-bistrimethylsilybenzylamine or N,N-bistrimethylsilyphenethylamine were shown to promote the reaction between t-butylimido bispyridine titanium(IV) (2a) and CO(2) to give near quantitative yields of symmetrical urea. Other symmetrical ureas could be produced from TiCl(4), amine and CO(2) in moderate to quantitative yields depending on the stoichiometry of amine present.

Type:Article
Title:Synthesis of ureas from titanium imido complexes using CO2 as a C-1 reagent at ambient temperature and pressure.
Location:England
DOI:10.1039/c1ob06576a
Language:English
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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