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Natural products containing an aziridine ring, such as mitomycin C and azinomycin B, exhibit antitumor activities by alkylating DNA via their aziridine rings; however, the biosynthetic mechanisms underlying the formation of these rings have not yet been elucidated. We herein investigated the biosynthesis of vazabitide A, the structure of which is similar to that of azinomycin B, and demonstrated that Vzb10/11, with no similarities to known enzymes, catalyzed the formation of the aziridine ring via sulfate elimination. To elucidate the detailed reaction mechanism, crystallization of Vzb10/11 and the homologous enzyme, AziU3/U2, in the biosynthesis of azinomycin B was attempted, and the structure of AziU3/U2, which had a new protein fold overall, was successfully determined. The structural analysis revealed that these enzymes adjusted the dihedral angle between the amino group and the adjacent sulfate group of the substrate to almost 180° and enhanced the nucleophilicity of the C6-amino group temporarily, facilitating the S

The mevalonate pathway is an upstream terpenoid biosynthetic route of terpenoids for providing the two five-carbon units, dimethylallyl diphosphate, and isopentenyl diphosphate. Recently, trans-anhydromevalonate-5-phosphate (tAHMP) was isolated as a new biosynthetic intermediate of the archaeal mevalonate pathway. In this study, we would like to report the first synthesis of tAHMP and its enzymatic transformation using one of the key enzymes, mevalonate-5-phosphate dehydratase from a hyperthermophilic archaeon, Aeropyrum pernix. Starting from methyl tetrolate, a Cu-catalyzed allylation provided an E-trisubstituted olefin in a stereoselective manner. The resulting E-olefin was transformed to tAHMP by cleavage of the olefin and phosphorylation. The structure of the synthetic tAHMP was unambiguously determined by NOESY analysis.

A facile method for deutrium incorporation into aldehydes by mild reduction of NaBD4 of aldehydes and MnO2 oxidation (98% D) is disclosed.

N-acylation reaction offers an opportunity to develop an efficient synthesis of amide group-containing molecules. We found that N-acyl carbazoles showed remarkable selectivity in transamidation. St...

The mevalonate pathway is an upstream terpenoid biosynthetic route of terpenoids for providing the two five-carbon units, dimethylallyl diphosphate, and isopentenyl diphosphate. Recently

The selective oxidation of alcohol

Conosilane A, an inhibitor of 11β-hydroxysteroid dehydrogenase type 1 isolated from Conocybe siliginea, is a tremulane sesquiterpene with highly oxygenated tetracyclic ring system. In this study, we report the synthesis of both enantiomers of conosilane A. The key steps of this synthesis involve asymmetric aldol reaction, furan-ring oxidation followed by transacetalization and intramolecular reductive Heck-type cyclization.

Strigolactones, a class of apocarotenoids, are known to function as rhizosphere semiochemicals and plant hormones. Canonical strigolactones consist of a tricyclic lactone (ABC-rings) and a butenolide moiety (D-ring), and their biosynthesis has been extensively studied. However, the process of BC-ring formation is yet to be clarified. The conversion of an 18-oxocarlactonoate derivative into racemic orobanchols was performed in the same way as in our previous study, which demonstrated that the BC-ring formation is possible “in flask” via acid-mediated cascade cyclization. The results strongly suggested that the mechanism of acid-mediated BC-ring formation may be based on the conrotatory electrocyclic reaction, and may provide significant insights into the process of BC-ring formation in strigolactone biosynthesis.

Salinipostins are cyclic enol-phosphotriesters isolated from a marine-derived Salinispora sp. as antimalarial compounds. Herein, the first enantioselective synthesis of salinipostin A was achieved. Organocatalyst-mediated asymmetric cyclopropanation and regioselective cyclopropane ring opening were the key steps.

From a gaseous mixture of Fe(CO)5 and CS2, sedimentary aerosol particles involving organometal compounds were produced under UV light irradiation at 313 nm. Chemical composition of the sedimentary aerosol particles was controlled by a magnetic field and by post-exposure with UV light. By applying a magnetic field up to 5 T, photochemical reactivity of Fe(CO)5 molecules was promoted and the amount of chemical species originating from Fe(CO)5 increased with increasing magnetic field. By irradiating UV light upon the deposited particles, solid-state photochemical reactions took place in the particles, and CO groups bonded to Fe atom were effectively evolved from the sedimentary aerosol particles. These methods can be utilized to modify chemical composition of the metal-containing sedimentary particles.