A modular synthesis of teraryl-based α-helix mimetics, part 1: Synthesis of core fragments with two electronically differentiated leaving groups

摘要

Teraryl-based α-helix mimetics have proven to be useful compounds for the inhibition of protein-protein interactions (PPI). We have developed a modular and flexible approach for the synthesis of teraryl-based α-helix mimetics. Central to our strategy is the use of a benzene core unit featuring two leaving groups of differentiated reactivity in the Pd-catalyzed cross-coupling used for terphenyl assembly. With the halogen/diazonium route and the halogen/triflate route, two strategies have successfully been established. The synthesis of core building blocks with aliphatic (Ala, Val, Leu, Ile), aromatic (Phe), polar (Cys, Lys), hydrophilic (Ser, Gln), and acidic (Glu) amino acid side chains are reported. Turn on: Teraryl-based α-helix mimetics can be effectively produced by sequential Suzuki coupling of a central core fragment featuring electronically differentiated leaving groups with aryl boronic pinacol esters (see scheme; dppf=1,1′-bis(diphenylphosphino) ferrocene, DME=dimethoxyethane, Pin=pinacol, Tf=trifluoromethanesulfonyl). With a set of only 2×18 building blocks, all permutations of α-helix mimetics can be produced.