Stereoselective Syntheses of trans-Anhydromevalonic Acid and trans-Anhydromevalonyl Group-Containing Natural Products.

Collective total syntheses of trans-anhydromevalonic acid (tAHMA) and trans-anhydromevalonyl (tAHM) group-containing natural products (pestalotiopin A, pestalotiopamide C, pestalotiopamide D, farinomalein E, eleutherazine B, and trichocyclodipeptide A) were achieved using tAHMA esters as key intermediates. To this end, tAHMA tert-butyl ester was newly prepared by Z-vinyltosylation of tert-butyl 3-oxo-5-((triisopropylsilyl)oxy)pentanoate followed by the Negishi cross-coupling reaction with Me2Zn. tAHMA esters were converted to the target natural products via esterification or amidation. Comparison of the spectroscopic data of synthetic and natural products confirmed the E-configuration of the tAHM moieties in the natural products.

Total Synthesis and Structure Confirmation of trans-Anhydromevalonate-5-phosphate, a Key Biosynthetic Intermediate of the Archaeal Mevalonate Pathway.

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.

Selective oxidation of alcohol-d 1 to aldehyde-d 1 using MnO2.

The selective oxidation of alcohol-d 1 to prepare aldehyde-d 1 was newly developed by means of NaBD4 reduction/activated MnO2 oxidation. Various aldehyde-d 1 derivatives including aromatic and unsaturated aldehyde-d 1 can be prepared with a high deuterium incorporation ratio (up to 98% D). Halogens (chloride, bromide, and iodide), alkene, alkyne, ester, nitro, and cyano groups in the substrates are tolerated under the mild conditions.