A facile approach towards amidinophenylalanine derivatives as building blocks for the synthesis of non-natural peptides and peptidomimetics

N-sulfonyl peptide-hybrids as a new class of dengue virus protease inhibitors

Dengue virus (DENV) from the Flaviviridae family causes an epidemic disease that seriously threatens human life. The viral serine protease NS2B-NS3 is a promising target for drug development against DENV and other flaviviruses. We here report the design, synthesis, and in-vitro characterization of potent peptidic inhibitors of DENV protease with a sulfonyl moiety as N-terminal cap, thereby creating sulfonamide-peptide hybrids. The in-vitro target affinities of some synthesized compounds were in the nanomolar range, with the most promising derivative reaching a K_i value of 78 nM against DENV-2 protease. The synthesized compounds did not have relevant off-target activity nor cytotoxicity. The metabolic stability of compounds against rat liver microsomes and pancreatic enzymes was remarkable. In general, the integration of sulfonamide moieties at the N-terminus of peptidic inhibitors proved to be a promising and attractive strategy for further drug development against DENV infections.

Synthesis of Boronated Amidines by Addition of Amines to Nitrilium Derivative of Cobalt Bis(Dicarbollide)

A series of novel cobalt bis(dicarbollide) based amidines were synthesized by the nucleophilic addition of primary and secondary amines to highly activated B-N+≡C-R triple bond of the propionitrilium derivative [8-EtC≡N-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)]. The reactions with primary amines result in the formation of mixtures of E and Z isomers of amidines, whereas the reactions with secondary amines lead selectively to the E-isomers. The crystal molecular structures of E-[8-EtC(NMe2)=HN-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)], E-[8-EtC(NEt2)=HN-3,3'-Co(1,2- C2B9H10)(1',2'-C2B9H11)] and E-[8-EtC(NC5H10)=HN-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] were determined by single crystal X-ray diffraction.