- Regioselective oxidation of indoles to 2-oxindoles
-
Facile regioselective oxidation of indoles to 2-oxindoles promoted by sulfuric acid adsorbed on silica gel is reported. The demonstrated practical site-selective heterogeneous oxidation reactions conveniently take place with a broad substrate scope and functional group tolerances. The present oxidation strategy is also employed to accomplish the total synthesis of natural products donaxaridine and donaxarine. On the basis of analytical and spectral data it is evidenced that donaxarine stays in equilibrium with its hydrated ring opened form. The structural features essential for this type of oxidation and plausible mechanism are discussed in brief.
- Shelar, Santosh V.,Argade, Narshinha P.
-
p. 6671 - 6677
(2019/07/16)
-
- Collective synthesis and biological evaluation of tryptophan-based dimeric diketopiperazine alkaloids
-
A concise two one-pot synthesis of WIN 64821, eurocristatine, 15,15′-bis-epi-eurocristatine, ditryptophenaline, ditryptoleucine A, WIN 64745, cristatumin C, asperdimin, naseseazine A, and naseseazine B is detailed, based on a unique bioinspired dimerization reaction of tryptophan derivatives in aqueous acidic solution and a one-pot procedure for the construction of diketopiperazine rings. Total yields of these alkaloid syntheses were from 10 up to 27 %. In addition, 1′-(2-phenylethylene)-ditryptophenaline was synthesized by using three one-pot operations. The studies detailed herein provided synthesized natural products for inhibitory activities of ubiquitin-specific protease 7 (USP7) and foam cell formation in macrophages. The newly listed biological evaluation for tryptophan-based dimeric diketopiperazine alkaloids discovered 15,15′-bis-epi-eurocristatine, 1′-(2-phenylethylene)-ditryptophenaline, and WIN 64745 as new drug candidates. All in one: A concise synthesis of tryptophan-based dimeric diketopiperazine alkaloids (see scheme) is detailed based on a unique bioinspired dimerization reaction of tryptophan derivatives and a one-pot procedure for construction of diketopiperazine rings. Some of the synthetic alkaloids were discovered as new drug candidates for cancer or atherosclerosis therapy.
- Tadano, Shinji,Sugimachi, Yukihiro,Sumimoto, Michinori,Tsukamoto, Sachiko,Ishikawa, Hayato
-
supporting information
p. 1277 - 1291
(2016/01/25)
-
- Synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine and (±)-convolutamydines A and E, through enolization-Claisen rearrangement of 2-allyloxyindolin-3-ones
-
Claisen rearrangement triggered by enolization of 2-allyloxyindolin-3-ones with DBU was performed in order to prepare 3-allyl-3-hydroxyindolin-2-ones. Total synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine, as well as (±)-convolutamydines A
- Kawasaki, Tomomi,Nagaoka, Miyuki,Satoh, Tomoko,Okamoto, Ayako,Ukon, Rie,Ogawa, Atsuyo
-
p. 3493 - 3503
(2007/10/03)
-