Au(I) Catalyzed Synthesis of Densely Substituted Pyrazolines and Dihydropyridines via Sequential Aza-Enyne Metathesis/6π-Electrocyclization

Asymmetric Auto-Tandem Catalysis with Chiral Organosuperbases: Intramolecular Cyclization/Enantioselective Direct Mannich-Type Addition Sequence

An enantioselective addition reaction of alkynyl esters with imines was developed under asymmetric autotandem catalysis with a chiral Brønsted base. A chiral bis(guanidino)iminophosphorane organosuperbase, which has much higher basicity than that of conventional chiral organic bases, efficiently promoted both the intramolecular cyclization for the construction of a benzofuran ring or a benzothiophene ring and the sequential enantioselective direct Mannich-type reaction of diarylmethane derivatives, affording enantio-enriched diarylalkane derivatives that are otherwise difficult to access.

One-Pot Synthesis of Pentasubstituted Pyridines following the Gold(I)-Catalyzed Aza-Enyne Metathesis/6π-Electrocyclization-Aromatization Sequence

The one-pot de novo synthesis of pentasubstituted pyridines was realized following the process of Au(I)-autotandem catalysis and subsequent aromatization. The process involves aza-enyne metathesis with aryl propiolates to yield 1-azabutadienes and their addition/6π-electrocyclization sequence with the other propiolate units. The resultant 1,4-dihydropyridines were aromatized to furnish the pyridines in the presence of atmospheric oxygen. The aryl propiolates were regioselectively incorporated into the ring system to afford 2-arylpyridines as the sole product.

Inhibition of gastric H+,K+-ATPase by new dihydropyrazole derivative KYY-008

The gastric proton pump (H⁺,K⁺-ATPase) responsible for the H⁺ secretion of gastric acid is an essential therapeutic target for acid-related diseases. H⁺,K⁺-ATPase belongs to a P₂-type ATPase family. Here, we examined the effects of a newly synthesized dihydropyrazole derivative KYY-008 on the H⁺,K⁺-ATPase. KYY-008 concentration-dependently inhibited the enzyme activity of the ATPase in the membrane fractions prepared from isolated hog gastric mucosa and from human kidney HEK293 cells in which gastric H⁺,K⁺-ATPase is exogenously expressed. The IC₅₀ values in these samples were 3.4 μM and 3.7 μM, respectively. In addition, KYY-008 significantly inhibited the H⁺,K⁺-ATPase-derived H⁺ uptake into the tightly sealed vesicles prepared from the hog gastric mucosa. In contrast, KYY-008 has no effect on the activities of other P₂-type ATPases such as Na⁺,K⁺-ATPase and Ca²⁺-ATPase. KYY-008 did not change the ionic currents of voltage-dependent Ca²⁺ channels, that were potential targets for some dihydropyrazole derivatives. Together, we discovered a new dihydropyrazole derivative which acts as a selective inhibitor of gastric H⁺,K⁺-ATPase.