Synthesis and Conformational Analysis of Epindolidione-Derived Peptide Models for β-Sheet Formation

Article abstract of DOI:10.1021/jo00302a033

Synthesis of 2,8-diaminoepindolidione (2,8-diaminodibenzo<1,5>naphthyridine-6,12(5,11H)-dione) in 19percent yield from p-nitroaniline is reported, as well as further conversion to 2,8-bis(Boc-L-Pro-Xxx)epindolidione (Xxx=Gly, D-Ala) and then to 2,8-bis(OC(Yyy-Zzz-NMe2)-L-Pro-Xxx)epindolidione (Yyy=Gly, L-Ala, D-Ala; Zzz=Gly, L-Phe, D-Phe).The β-turn-forming tendencies of the series 2,8-bis(X-L-Pro-D-Ala)epindolidione, where X=Ac, Boc, and COGlyOEt, are assigned from 1H NMR evidence.