Zinc reagents carbamates

Carbonates, like esters, can be cleaved by basic hydrolysis, but generally are much less susceptible to hydrolysis because of the resonance effect of the second oxygen. In general, carbonates are cleaved by taking advantage of the properties of the second alkyl substituent (e.g., zinc reduction of the 2,2,2-trichloroethyl carbonate). The reagents used to introduce the carbonate onto alcohols react readily with amines as well. As expected, basic hydrolysis of the resulting carbamate is considerably more difficult than basic hydrolysis of a carbonate. 

Other reagents are available for introducing the 2-oxo group. Thus, 2-amino-3-pyridyl phenyl ketone, ethyl carbamate, and zinc chloride, fused for 45 min at 230°C, gave a good yield of 4-phenylpyrido[2,3-d ] pyrimidin-2-one (see 3). In addition, 2-ferf-butylamino-3-pyridylphenylketonimine, phosgene, and triethylamine, stirred in cold benzene for 10 min, produced... 

---