Enantioselective Synthesis and Biological Activity of (3S,4R)- and (3S,4S)-3-Hydroxy-4-hydroxymethyl- 4-butanolides in Relation to PGE2

A Cooperative Ternary Catalysis System for Asymmetric Lactonizations of α-Ketoesters

A general and enantioselective N-heterocyclic carbene (NHC)-catalyzed lactonization of simple enals and α-ketoesters has been discovered using a new ternary cooperative catalytic system. The highly selective annulation was achieved by using a combination of a chiral NHC, a hydrogen-bond donor, and a metal salt, facilitating self-assembly of the reactive partners. A proposed model for this new mode of NHC chiral relay catalysis is supported by experimental and computational mechanistic studies.

Naturally occurring hybrids derived from γ-amino acids and sugars with potential tail to tail ether-bonds

The basic substances of life include various amino acids and sugars. To search such molecules is the precondition to understand the essential nature. Here we reported four unprecedented hybrids of γ-amino acids and sugars from the roots of Ranunculus ternatus, which possess potential tail to tail ether-connected (6,6-ether-connected) modes in the sugar moiety. The structures of these hybrids were elucidated by extensive analyses of spectra and calculated electronic circular dichroism (ECD) method.

Secondary Metabolites from the Fungus Emericella Nidulans

A new polyketide derivative koninginin H (1), has been isolated from the fungus Emericella nidulans, together with koninginin E (2), koninginin A (3), trichodermatide B (4), citrantifidiol (5), (4 S,5 R)-4-hydroxy-5-methylfuran-2-one (6), the glycerol derivatives gingerglycolipid B (7), (2 S)-bis[9 Z,12 Z]-1- O, 2- O-dilinoleoyl-3- O-[α-D-galactopyranosyl-(1″→6′)β-D-galactopyranosyl]glycerol (8), (2 S)-bis[9 Z,12 Z]-1- O, 2- O-dilinoleoyl-3- O-β-D-galactopyranosylglycerol (9), the cerebroside flavuside B (10), and the known sterols β-sitosterol glucoside and ergosta-5,7,22-trien-3-ol. Their structures were established by extensive NMR studies (1H NMR, 13C NMR, DEPT, 1H–1H COSY, HSQC, HMBC) and mass spectrometry. The antibacterial, antimalarial, antifungal and antileishmanial activities of compounds 1–10 were examined and the results indicated that compound 4 showed good antifungal activity against Cryptococcus neoformans with an IC50 value of 4.9 μg/mL.

Prins-Type Synthesis and SAR Study of Cytotoxic Alkyl Chloro Dihydropyrans

A series of functionalized tetrahydropyran and dihydropyran derivatives was synthesized by means of a Prins-type cyclization between unsaturated alcohols and several aldehydes. An unprecedented dimer bearing two 4-chloro-5,6-dihydro-2H-pyran scaffolds was obtained in high yield. A panel of three representative human solid tumor cells from diverse origin was used to assess the cytotoxicity of the compounds. Overall, the results show the relevance of the chlorovinyl group in the biological activity, and 2-alkyl-4-chloro-5,6-dihydro-2H-pyrans represent interesting leads for further chemical modifications and biological studies.