X-ray structural analyses of two a,y-diketo esters and one a,y-diketo acid, which are amino acid antagonists, have shown them all to be present in the solid state in the a,ßunsaturated y-keto enolic form. The structures of the esters /3-acetyl-pyruvic acid methyl ester (1) and 2-oxo-cyclopentyl-glyoxylic acid ethyl ester (3) are stabilized by intramolecular O---H(-O) hydrogen bonds involving th...

The one-carbon bridge stereochemistry of bicyclo[3.3.1]nonane products formed in the Robinson annulation reactions of 2-substituted cyclohex-2-enones was investigated. In contrast to previous reports, it was found that the major diastereomer formed places the one-carbon bridge substituent anti to the beta-keto ester/amide unit introduced in the Robinson annulation. This stereoselectivity appear...

Labeled and unlabeled prostacyclin and 6-keto-PGF1, were infused into healthy volunteers; urine was chromatographed on different systems including high pressure liquid chromatography. The peaks obtained by the latter method were derivatized to the methoxime methyl ester trimethyl silyl ether and analyzed by gasliquid chromatography-mass spectrometry. After infusion of prostacyclin the follo...

We show a convenient decarboxylative aldol process using a scandium catalyst and a PYBOX ligand to generate a series of highly functionalized chiral α-hydroxy esters. The protocol tolerates a broad range of β-keto acids with inactivated aromatic and aliphatic α-keto esters. The possible mechanism is rationalized.

The red yeast Xanthophyllomyces dendrorhous is an established platform for the synthesis of carotenoids. It was used for the generation of novel multi oxygenated carotenoid structures. This was achieved by a combinatorial approach starting with the selection of a β-carotene accumulating mutant, stepwise pathway engineering by integration of three microbial genes into the genome and finally the ...

Silica-bonded n-propyldiethylenetriamine sulfamic acid (SBPDSA) was found as an efficient solid acid for the synthesis of coumarins. Coumarin derivatives were obtained via the Pechmann condensation reaction of phenols and β-keto-esters at 80 oC under solvent-free conditions. Also, biscoumarins were obtained via the condensation of aldehydes and 4-hydroxycoumarin in water at reflux conditions. T...

The first decarboxylative Mannich reaction employing β-keto acids, catalyzed by cinchonine-derived bifunctional thiourea catalyst has been described. The desired β-amino ketones were obtained in excellent yields and with moderate to good enantioselectivities.

The resin of Boswellia species has been used as incense in religious and cultural ceremonies and in medicines since time immemorial. Boswellia serrata (Salai/Salai guggul), is a moderate to large sized branching tree of family Burseraceae (Genus Boswellia), grows in dry mountainous regions of India, Northern Africa and Middle East. Oleo gum-resin is tapped from the incision made on the trunk of...