79677-62-6Relevant articles and documents
RA-XXV and RA-XXVI, Bicyclic Hexapeptides from Rubia cordifolia L.: Structure, Synthesis, and Conformation
Hitotsuyanagi, Yukio,Hirai, Masahito,Odagiri, Masumi,Komine, Miho,Hasuda, Tomoyo,Fukaya, Haruhiko,Takeya, Koichi
, p. 205 - 215 (2019)
Two RA-series bicyclic hexapeptides, RA-XXV (4) and RA-XXVI (5), which have no N-methyl group at Tyr-5, were isolated from the roots of Rubia cordifolia L. Their amino acid compositions and sequences were determined by interpretation of MS, and 1D and 2D NMR data and their relative structures were elucidated by XRD analysis of 4 and RA-XXVI acetate (6). The absolute stereochemistry of 4 was established by the total synthesis of 4, and that of 5, by the chemical correlation with 4. Peptides 4 and 5 exhibited cytotoxicity toward human promyelocytic leukemia HL-60 (IC50=0.062 and 0.066 μm, respectively) and human colonic carcinoma HCT-116 (IC50=0.028 and 0.051 μm, respectively) cell lines. Analysis of the conformational structures of 4 and 6 in the crystalline state and those of 4 and 5 in solution revealed that the N-methyl group at Tyr-5 functions to make this series of peptides preferentially adopt the active conformation.
Formal Total Synthesis of Diazonamide A by Indole Oxidative Rearrangement
David, Nadège,Pasceri, Raffaele,Kitson, Russell R. A.,Pradal, Alexandre,Moody, Christopher J.
supporting information, p. 10867 - 10876 (2016/07/27)
A short formal total synthesis of the marine natural product diazonamide A is described. The route is based on indole oxidative rearrangement, and a number of options were investigated involving migration of tyrosine or oxazole fragments upon oxidation of open chain or macrocyclic precursors. The final route proceeds from 7-bromoindole by sequential palladium-catalysed couplings of an oxazole fragment at C-2, followed by a tyrosine fragment at C-3. With the key 2,3-disubstituted indole readily in hand, formation of a macrocyclic lactam set the stage for the crucial oxidative rearrangement to a 3,3-disubstituted oxindole. Notwithstanding the concomitant formation of the unwanted indoxyl isomer, the synthesis successfully delivered, after deprotection, the key oxindole intermediate, thereby completing a formal total synthesis of diazonamide A.
The diazo route to diazonamide A: Studies on the tyrosine-derived fragment
Palmer, Francine N.,Lach, Franck,Poriel, Cyril,Pepper, Adrian G.,Bagley, Mark C.,Slawin, Alexandra M. Z.,Moody, Christopher J.
, p. 3805 - 3811 (2007/10/03)
Various approaches to the tyrosine-derived fragment of the marine secondary metabolite diazonamide A are described. Initial efforts were focused on the originally proposed structure of the natural product, and a feasibility study established that a model
