No abstract

A range of reported methods have been assessed for the synthesis of two coumarin fluorophores containing azides, 1a and 2, for subsequent "click" modification. In the case of 1a reported methods were successfully applied, but the resulting azide proved to be rather unstable and appears more suited to in-situ generation and conversion to the "click" triazole. In the case of 2, reported methods for the synthesis of precursor 5 were ineffective in two cases and resulted in either no bromination -to the carbonyl or the formation of multiple unwanted side-products, some of which were isolated, 6-13. The use of CuBr 2 in excess or Br 2 in 50% HBr in acetic acid did result in the isolation of 5, which could be efficiently converted to 2 using excess NaN 3 in THF.

A Mild, Copper-Catalyzed Amide Deprotection Strategy: Use of tert-Butyl as a Protecting Group. -A catalytic amount of Cu(OTf) 2 can be used to affect a mild de-tert-butylation of N,N-disubstituted amides, e.g. (I), (III), and (V). This protocol can also be applied to di-Boc-protected amino acids (VIII). -(EVANS, V.; MAHON, M. F.; WEBSTER*, R. L.; Tetrahedron 70 (2014) 41, 7593-7597, http://dx.doi.org/10.1016/j.tet.2014.07.080 ; Univ. Bath, Bath BA2 7AY, UK; Eng.) -M. Paetzel 10-058