691394-91-9Relevant academic research and scientific papers
Synthesis of Pentacyclic Framework of Herquline A
Kim, Thomas Taehyung,Lee, Chungwoo,Heo, Seongrok,Lee, Hee-Seung,Han, Sunkyu
supporting information, p. 3882 - 3885 (2021/10/14)
The highly strained bowl-shaped pentacyclic structure of herquline A has rendered it one of the most difficult problems in organic synthesis yet to be solved. The challenges associated with the synthesis of herquline A have been well documented in four Ph.D. dissertations and in multiple reports regarding syntheses of its structurally simpler congeners. Herein, we report the construction of the pentacyclic core of herquline A that contains both N10?C2 and C3?C3′ bonds. The key for success was the development of the tandem aza-Michael addition/enolate capture protocol that set the stage for subsequent palladium catalyzed C3(sp2)?C3′(sp2) coupling reaction. Ensuing oxidative dearomatization of the left aryl ring allowed the formation of the pentacyclic diketone core of herquline A.
Scalable Synthesis of Mycocyclosin
Zhu, Xu,McAtee, Christopher C.,Schindler, Corinna S.
supporting information, p. 2862 - 2866 (2018/05/29)
We report herein the scalable total synthesis of the secondary metabolite, mycocyclosin, initially isolated from Mycobacterium tuberculosis. Mycocylosin bears a highly strained 3,3′-dityrosine biaryl system which arises biosynthetically from an intramolec
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.
Isolation, structure determination, and synthesis of allo-RA-V and neo-RA-V, RA-series bicyclic peptides from Rubia cordifolia L.
Hitotsuyanagi, Yukio,Odagiri, Masumi,Kato, Saori,Kusano, Jun-Ichi,Hasuda, Tomoyo,Fukaya, Haruhiko,Takeya, Koichi
supporting information; experimental part, p. 2839 - 2846 (2012/04/04)
Two bicyclic hexapeptides, allo-RA-V (4) and neo-RA-V (5), and one cyclic hexapeptide, O-seco-RA-V (6), were isolated from the roots of Rubia cordifolia L. Their gross structures were elucidated on the basis of spectroscopic analysis and X-ray crystallography of compound 5. The absolute stereochemistry of compounds 4 and 5 were established by their total syntheses, and the absolute stereochemistry of compound 6 by chemical correlation with deoxybouvardin (3). Comparison of the 3D structures of highly active RA-VII (1) with less-active compounds 4 and 5 suggests that the orientation of the Tyr-5 and/or Tyr-6 phenyl rings plays a significant role in their biological activity. The isolation of peptides 4-6, along with compound 3, and the comparison of their structures seem to indicate that peptide 6 may be the common precursor to bicyclic peptides 3-5 in the plant. Allo allo: Two cycloisodityrosine-modified congeners of deoxybouvardin (RA-V) have been isolated from the roots of Rubia cordifolia. Comparison of their structures with that of RA-VII revealed that the orientation of one or both of the Tyr-5 and Tyr-6 phenyl rings plays an essential role in expressing the cytotoxic activity. Copyright
Synthesis and characterization of the arylomycin lipoglycopeptide antibiotics and the crystallographic analysis of their complex with signal peptidase
Liu, Jian,Luo, Chuanyun,Smith, Peter A.,Chin, Jodie K.,Page, Malcolm G. P.,Paetzel, Mark,Romesberg, Floyd E.
supporting information; experimental part, p. 17869 - 17877 (2012/01/05)
Glycosylation of natural products, including antibiotics, often plays an important role in determining their physical properties and their biological activity, and thus their potential as drug candidates. The arylomycin class of antibiotics inhibits bacte
Approaches to the quaternary stereocentre and to the heterocyclic core in diazonamide A using the Heck reaction and related coupling reactions
Booker, James E. M.,Boto, Alicia,Churchill, Gwydion H.,Green, Clive P.,Ling, Matthew,Meek, Graham,Prabhakaran, Jaya,Sinclair, David,Blake, Alexander J.,Pattenden, Gerald
, p. 4193 - 4205 (2008/09/19)
In model studies towards the quaternary centre at the heart of diazonamide A (early structure 2; revised structure 1), cyclisations of the alkene-substituted iodoaryls 4, 13, 18 and 23, under Heck reaction conditions, were shown to lead to the corresponding benzodihydrofuran 5, benzofuranone 14 and the oxindoles 19 and 24 respectively, in 50-80% yield. Further manipulation of the benzodihydrofuran 5 then led to the intermediates 30, 33 and 39, which make up parts of the oxazole-indole heterocyclic core in diazonamide A. Attempts to perform a corresponding 13-exo-trig Heck cyclisation from the precursor 46a, prepared from 44 and 45, leading to 47 were not successful. A similar outcome was obtained during attempts to effect Heck cyclisations from the ester 57 and the related ether 59. Treatment of the chromene-substituted iodoaryl 62 with Pd(OAc)2, PPh3 and Ag2CO3 led to the spirocycle 64 as a crystalline solid. X-Ray crystal structure analysis established that the quaternary centre in 64 had the same configuration as that present in diazonamide A (1). The Royal Society of Chemistry 2006.
