Chiral Salen–Aluminum Complexes as Catalysts for Enantioselective Aldol Reactions of Aldehydes and 5-Alkoxyoxazoles: An Efficient Approach to the Asymmetric Synthesis of syn and anti -Hydroxy--amino Acid Derivatives

Evans, David A.; Janey, Jacob M.; Magomedov, Nabi A.; Tedrow, Jason S.

doi:10.1002/1521-3773(20010518)40:10<1884::aid-anie1884>3.3.co;2-0

Cited by 42 publications

(67 citation statements)

References 1 publication

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“…66 Electron-rich aldehydes undergo slower turnover, so catalyst loading was increased to 10% to insure full conversion of aldehyde 64 to 68. Other investigators reported nearly identical results in this aldol-type reaction.…”

Section: First Convergent Approach Toward Ustiloxinmentioning

confidence: 99%

Evolution of the Total Syntheses of Ustiloxin Natural Products and Their Analogues

Evans

et al. 2008

J. Am. Chem. Soc.

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Ustiloxins A-F are antimitotic heterodetic cyclopeptides containing a 13-membered cyclic core structure with a synthetically challenging chiral tertiary alkyl-aryl ether linkage. The first total synthesis of ustiloxin D was achieved in 31 linear steps using an S N Ar reaction. An nOe study of this synthetic product showed that ustiloxin D existed as a single atropisomer. Subsequently, highly concise and convergent syntheses of ustiloxins D and F were developed by utilizing a newly discovered ethynyl aziridine ring-opening reaction in a longest linear sequence of 15 steps. The approach was further optimized to achieve a better macrolactamization strategy. Ustiloxins D, F and eight analogues (14-MeO-ustiloxin D, four analogues with different amino acid residues at the C-6 position, and three (9R, 10S)-epi-ustiloxin analogues) were prepared via the second generation route. Evaluation of these compounds as inhibitors of tubulin polymerization demonstrated that variation at the C-6 position is tolerated to a certain extent. In contrast, the S configuration of the C-9 methylamino group and a free phenolic hydroxyl group are essential for inhibition of tubulin polymerization. Antimitotic agentsAntimitotic agents have long been of interest to scientists and physicians, even before their precise mechanism of action could be articulated. Most of these compounds interfere with microtubule assembly and functions thus resulting in mitotic arrest of eukaryotic cells. There are a number of natural and synthetic compounds that interfere with tubulin function to inhibit the formation of microtubules. 1 Such antimitotic agents exhibit a broad range of biological activities and can be used for medicinal and agrochemical purposes, acting as anticancer, antifungal, or anthelmintic agents. Moreover, tubulin binding compounds are valuable for understanding basic mechanisms involved in the dynamics of the microtubule network. 2 Mitotic arrest is of importance in cancer chemotherapy, since tubulin is an established chemotherapeutic target. In addition to the widely used vinca alkaloids and taxoids, many other antimitotic agents are currently in clinical or preclinical development. 3 Newer potential targets NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript that may cause mitotic arrest are in development as well. Although cancer chemotherapy is a very important goal being extensively investigated, the mechanism of action of the naturally occurring peptides that inhibit tubulin polymerization remains a challenging problem. Attempts to establish a relationship among the tubulin binding peptides have only had limited success. [4][5][6][7][8] As a result, the mechanism of action of peptidic antimitotic agents is not completely elucidated and deserves further investigation. UstiloxinsThe first peptide shown to interact with tubulin was phomopsin A (Error! Reference source not found.). [9][10][11][12][13] Since then, a number of peptides and depsipeptides were found to disrupt cellular microtubules. These compo...

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Section: First Convergent Approach Toward Ustiloxinmentioning

confidence: 99%

Evolution of the Total Syntheses of Ustiloxin Natural Products and Their Analogues

Evans

et al. 2008

J. Am. Chem. Soc.

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“…In the aim of preparation of rigid chiral precursor in chiral Schiff base ligands, most of researchers used either pure or racemic molecular backbones [7][8][9][10][11][12][13][14][15][16][17][18]. For example, the use of a chiral biaryl diamine structure in tetradentate ligands was explored by Lions and Martin in 1957 [7] and 1960 [8].…”

Section: Introductionmentioning

confidence: 99%

Chirality at octahedral centres determined by tetradentate Schiff base ligands

Rudbari

Farsani

Lanza

et al. 2015

Comptes Rendus. Chimie

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“…cis-Oxazole (>99% ee) is also epimerized to trans-oxazole by treatment with a catalytic amount of DBU (1) (cis:trans ¼ 5 : 95, > 99% ee) [66] (Scheme 3.40).…”

Section: Isomerizationmentioning

confidence: 99%