Insertion into amides of non-metallic elements

Carbon dioxide can also form carbamates by reaction with amides of non-metallic elements [78-84, 136-144]. Most examples reported in the literature deal with amides of silicon, germanium, and phosphorus. Among these, the insertion of the heterocumulene into the P-N bond of hexaalkylphosphorus triamides P(NR2)3, which affords phosphocarbamates species of formula P(NR2)3 (02CNR2) t, has received particular attention for its potential in chemical synthesis, because this reaction opens a route to the phosgeneless synthesis of carbamate esters [138,139] and ureas [140]. 

Mechanistic information on the pathway of these insertion reactions are sparse. A mechanism similar to that sununarized by (4.22a) and (4.23), and involving the intermediacy of carbamic acid formed by the action of CO2 on adventitious amine present in the reaction medium, seems to be operative for the formal insertion of 

---

See also in sourсe #XX -- [ , , ]

---