Oxidative Carbonylation of Arylamines

N -Disubstituted ureas find their applications in areas such as pharmaceuticals, pesticides and dyes. Whites group has shown the 

3 Ihiolative Lactonization of Alkynes with Double CO Incorporation 

Catalysis works best when some amount of phosphine particularly 1,2-bis(diphenylphosphino)ethane (DPPE) is used as additive along with [Co2(CO)gj. Yield of the thio lactone is susceptible to the amoxmt of solvent used. Reaction goes very well in higher dilution. Yields of double CO inserted products vary with type of thiols and acetylenes used. Reaction works best with ethanethiol (70% yields). Aromatic thiols were less effective and monocarbonylation product forms in major byproduct [43]. 

Further lowering of the pressure leads to decrease in yields. Reactions of substituted phenyl ring shows that electron-donating substituents seem to have no influence on the product yield, whereas electron-withdrawing substituents like the CF group lead to lower yields. This observation might be explained by the lower nucleophilicity of acceptor substituted alkynes. 

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