Transfer of Carbamate Group to Epoxides

Other metal-amides, such as TiCp(NMe2)3, W2(NMe2)s and W(NMe2)s [77b], or EtZn(NPh2) and Et2Al(NPh2) [77c], have also been used in the synthesis of trans-2-hydroxycyclohexyl N,N-disubstituted carbamates through the same route. 

Monocarbamates of 1,2-diols can be obtained also by the direct reaction of epoxide with primary or secondary aliphatic amines in the presence of C02 

five- and six-membered cyclic carbamates have been synthesized by the reaction of 2-(l-haloalkyl)-oxiranes with C02 and primary aliphatic amines [81]. Notably, 5-substituted 2-oxazolidinones have been prepared in good yield (51-94%) by reacting 2-aminomethyloxiranes with C02 (0.1 MPa), in MeOH, at room temperature [82]. 

The use of oxetanes has been also explored. Both primary and secondary aliphatic amines react with oxetanes, under C02 (4MPa), at 373-393 K, in the absence of any catalyst, to afford monocarbamates of 1,3-propanediols, together with amino alcohols as side products [84]. 

The transfer of a carbamate moiety to olefins has been documented only in very few cases, using activated unsaturated substrates. For example, Yoshida and Inoue reported the selective (100%) formation of 1-ethoxyethyl N,N-dialkylcarbamate esters by the reaction of C02 (5 MPa) with ethyl vinyl ether and secondary amines R2NH (R = Me, Et) in the absence of any catalyst (Equation 6.11) [85]. 

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