Total syntheses of the highly potent anti-cancer polyacetylenes, (S)-18-hydroxyminquartynoic acid, (S)-minquartynoic acid and (E)-15,16-dihydrominquartynoic acid

Anti-oral common pathogenic bacterial active acetylenic acids from Thesium chinense Turcz

Discovery of agents for oral infectious diseases is always encouraged in natural products chemistry. A bioassay-guided isolation led to the isolation of two new acetylenic acids (1, 2) along with seven known ones (3-9) from the ethanol extract of Thesium chinense Turcz, a commonly used oral anti-bacterial and anti-inflammatory herb. Their structures were elucidated on the basis of spectroscopic and chemical evidence. Exocarpic acid (3) demonstrated the most promising activity against three tested oral pathogenic bacterial strains, Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mutans, with minimum inhibitory concentration values of 0.86, 3.43, and 13.70 μg/mL, respectively. Compounds 1, 2, 4, 5 and 7 also showed potential activities against periodontal bacteria (P. gingivalis, F. nucleatum).

Dual stereocontrolled alkylation of aldehydes with polystyrene-supported nickel complexes derived from α-amino amides

Nickel(ii) complexes derived from α-amino amide ligands anchored to gel-type and monolithic polymers act as efficient catalysts for the enantioselective addition of dialkylzinc reagents to aldehydes.

Asymmetric reduction of diynones and the total synthesis of (S)-panaxjapyne A

The asymmetric transfer hydrogenation of a series of diynones has been achieved in high conversion and enantiomeric induction. When R(1) is a phenyl group, a competing alkyne reduction takes place; however, when R(1) is an alkyl group, this side-reaction is not observed. The application of the reduction to the total synthesis of the natural product (S)-panaxjapyne A in high enantiomeric excess is described.

Asymmetric catalytic alkynylation of acetaldehyde: application to the synthesis of (+)-tetrahydropyrenophorol

By controlling the kinetics of alkynylation over aldolisation (by slowing adding the acceptor), the challenging asymmetric catalytic alkynylation of acetaldehyde has been realized. This protocol yields the corresponding attractive synthons in good to excellent enantiocontrol and shows broad tolerance and applicability. This was highlighted by its application to the synthesis of several natural products such as the rapid construction of the macrocyclic diolide (+)-tetrahydropyrenophorol.