1,3-Dipolar cycloadditions of MeOPEG-bounded azides

One-Pot Parallel Synthesis of 5-(Dialkylamino)tetrazoles

Two protocols for the combinatorial synthesis of 5-(dialkylamino)tetrazoles were developed. The best success rate (67%) was shown by the method that used primary and secondary amines, 2,2,2-trifluoroethylthiocarbamate, and sodium azide as the starting reagents. The key steps included the formation of unsymmetrical thiourea, subsequent alkylation with 1,3-propane sultone and cyclization with azide anion. A 559-member aminotetrazole library was synthesized by this approach; the overall readily accessible (REAL) chemical space covered by the method exceeded 7 million feasible compounds.

1,2,3-Triazoles

Rapid progress in the synthetic application of benzotriazole derivatives in the last 20 years has resulted in over 1000 scientific papers on the subject. This fact is reflected in Section 5.01.7, which involves almost a half of the volume of this chapter. The section is arranged according to hybridization of the C-α atom and atomic numbers of the atoms in positions β and γ to allow an easy access to the material of interest. Recent discovery of copper catalysis in [3+2] cycloadditions of azides to acetylenes, the so-called ‘click chemistry’, which boosted application of the 1,2,3-triazole derivatives, especially in medicinal chemistry, is presented in Section 5.01.9. From the point of view of practical applications, Section 5.01.11 is organized according to the number, position, and combination of the substituents at the aromatic rings. Another novel feature that has no precedence in the previous editions of Comprehensive Heterocyclic Chemistry is an addition of triazole and benzotriazole complexes with various transitions metals to Section 5.01.4.

C-Terminally PEGylated hGH-derivatives

A two-step strategy was used for the preparation of C-terminally PEGylated hGH-derivatives. In a first step a CPY-catalyzed transpeptidation was performed on hGH-Leu-Ala, introducing reaction handles, which were used in the second step for the ligation of PEG-moieties. Both oxime-ligation and copper(I) catalyzed [2+3]-cycloaddition reactions were used for the attachment of PEG-moieties. The biological data show a dependency of the potency of the hGH-derivatives on both size as well as shape of the PEG-group.