Recently the anticancer natural products having characteristic ene-yne structures, calicheamicin (1), esperamicin (2), dynemicin A (3), and neocarzinostatin chromophore (4), has been discovered. Their characteristic ene-yne structures which can induce DNA cleavage are anticipated to deeply relate to their excellent antitumor activity. From their perspective toward developing new types of anticancer agents, extensive synthetic studies on these compounds have been carried out by employing various synthetic strategies. In this articie, these synthetic studies were introduced by classifing their methodologies employed to construct the cyclic ene-diyne or diene-diyne structures.

View full abstract

Syntheses of protected dipeptide isosteres bearing a trans carbon-carbon double bond in place of the amide linkage are described. Complete stereochemical control is employed in the synthesis of some biologically important isosteres with an alkyl group at the α-position of the δ-aminated β, γ-unsaturated esters. The synthesized isosteres have been incorporated into natural peptide analogues. The biological activites of some of alkene isosteres and peptide analogues are also presented.

View full abstract

The components in eleven kinds of citrus fruit peelings and hinoki cypress leaves were studied in order to develop the biological active substances, and eighty-six components including thirty-eight new compounds were isolated. Furthermore, several flavonoid glycosides and phenyl propanoid glycosides having a biological activity such as hypotensive or hypertensive effect were found. The important relations between the biological active substances and their structures are described. The new efficient methods were developed for the synthesis of biological active substances, for example, l-periryl alcohol, R-homocamphenilone, nojigiku alcohol, biguaiazulenone, and guaiazulenequinone from readily available, natural terpenoids, azulenoids, and the re-lated compounds.

View full abstract

Fluoride-ion induced desilylation of N, N-dialkyl-N-[(trimethylsilyl)methyl] (substituted benzyl) ammonium halides is reviewed. This new benzylammonium ylide formation reaction has the following merits : (1) the ylides are produced in quantitative yields in non-basic media at room temperature, and the ylide-anions locate on the carbons which had connected with the silyl groups, (2) the ylides initially isomerize to 5-alkylidene-6-(dialkylamino)methy1-1, 3-cyclohexadienes (isotoluene derivatives), and then they convert to Sommelet-Hauser rearrangement products and/or Stevens products, (3) although the ratios of both rearrangement products are influenced by the magnitude of electron-donating effect of the substituents, their ratios changed when the reac-tion was carried out in the presence of DBU or under irradiation by UV light.

View full abstract

Axially dissymmetric 2′-methyl- and 2′-methoxy-1, 1′-binaphthy1-2-carboxylic acid (1, 2) were effectively utilized as chiral derivatizing agents for discrimination of enantiomeric alcohols and amines by high performance liquid chromatography (HPLC) on silica gel. Especially, 2 had excellent chirality-recognizing ability, and could also be utilized for discrimination by ¹H NMR with the aid of Eu (fod)₃. The elution behavior of a pair of diastereomeric esters or amides on HPLC, as well as the NMR behavior of the diastereomers were rationally explained based on X-ray crystallographic analyses. Carbonyl cyanide derivatives of 1 and 2 were successfully applicable to resolution of β-adrenergic blocker enantiomers in biological fluids by HPLC. These diastereomeric esters were highly responsive to a fluorescence detector, the limit of detection being 200 pg and 30 pg (at a signal-to-noise ratio of 5), respectively. Also reported are convenient methods for the preparation of these reagents.

View full abstract

An efficient catalytic system is developed in the palladium (II)-induced oxidation reactions. The catalytic cycle depends on the autocycling redox of the coordinating ο-quinone ligand, trimethyl ester of coenzyme PQQ, under molecular oxygen. ο-Quinones work as a mediator to facilitate the Mn(III)TPPCl-catalyzed oxygenation reaction with hydrogen peroxide. The complex consisting of iron(II) chloride and the hetrocyclic mutidentate ligand, N, N′-bis[2-(4-imidazolyl) ethyl]-2, 6-pyridinedicarboxamide, catalyzes the epoxidation reaction of olefins with molecular oxygen in the absence of a reducing agent. Ligand and mediator play an important role in the transition metal complex induced oxidation reactions.

View full abstract