Reaction of Carbodiimides with trifluoromethanesulfonic acid
摘要:
Carbodiimides RN=C=NR (R = i-Pr, c-C6H11, Ph) react with trifluoromethanesulfonic acid with successive formation of O-triflyl isoureas RNHC(OTf)=NR, the isomeric N-triflyl ureas RN(Tf)C(O)NHR, and symmetrically substituted ureas RNHC(O)NHR. Carbodiimide Me3SiN=C=NSiMe3 in the reaction with TfOH undergoes desilylation to afford ester CF3SO2OSiMe3 and unsubstituted carbodiimide (cyanamide), which gives the products of di- and trimerization and urea.