Chemoselective Substitution in 4-Toluenesulfonamides and Carbamates by Di-tert-butyl Dicarbonate in the Presence of 4-Dimethylaminopyridine.
摘要:
Three novel derivatives of 1,2-ethylenediamine 1, 3 and 5 with 4-toluenesulfonyl and/or carbamate moieties have been prepared and submitted to reaction with a limiting amount of di-tert-butyl dicarbonate in the presence of catalytic amounts of 4-dimethylaminopyridine. All the reagents underwent completely selective substitution under these conditions and gave rise to the products 2a, 4 and 6 in 93-100% yields and the results were rationalized in terms of higher NH-acidity at the reaction sites. The products might be useful in synthesis of substituted 1,2-ethylenediamines. A similar approach might be applicable to many other diamines.
A new practical method for the synthesis of unsymmetrical ureas via high-pressure-promoted condensation of 2,2,2-trichloroethyl carbamates (Troc-carbamates) with amines
A new practical method for the synthesis of unsymmetrical ureas was achieved by condensation between 2,2,2-trichloroethyl carbamates (Troc-carbamates) and primary or secondary amines under high-pressure conditions. (c) 2005 Elsevier Ltd. All rights reserved.