The combined carbometalation-zinc homologation-allylation reaction of the resulting stereodefined 3,3-disubstituted allylmetal species with ketones allow the preparation of allylic vicinal diol derivatives in good yields with excellent diastereomeric ratios from commercially available alkynes. Two adjacent quaternary centers are formed with the concomitant formation of three new carbon-carbon b...

Quinazolinones are interesting materials because of their valuable biological effects. In this study some new 2,3-disubstituted-4(3H)quinqzolinone derivatives were synthesized from anthranilic acid in six steps by introducing a new chiral center to the aliphatic side chain of the quinazolinone. In the last step, a single acylation on the hydrazine moiety afforded final compounds. The structures...

A variety of ortho,ortho'-disubstituted hydrobenzoin derivatives are readily accessible through a directed ortho,ortho'-dimetalation strategy in which the alcohol functions in hydrobenzoin are deprotonated by n-BuLi and the resulting lithium benzyl alkoxides serve as directed metalation groups. The optimization and scope of this reaction are discussed, and the utility of this process is demonst...

New 1,3,4-thiadiazole, 6, 7 and 1,2,4-triazole derivatives, 8, 9 containing a phenylalanine moiety have been synthesized by intramolecular cyclization of 1,4-disubstituted thiosemicarbazides, 4, 5, in acid and alkaline media, respectively; the thiosemicarbazides were obtained by reaction of hydrazide 3 with appropriate aromatic isothiocyanates. The toxicity of the synthesized compounds was eval...

A copper-free allylic arylation reaction between 3,3-disubstituted allylic halides and triazene-softened aryl Grignard reagents has been developed. This protocol presents a direct and efficient way to construct both α- or γ-isomers with high regioselectivity under environmentally benign conditions. Various functional groups can be tolerated in the reaction and the products are of high value for...

Gold-catalyzed syntheses of 2,3-disubstituted indole derivatives from N-hydroxyanilines and allenes are described; these reactions require benzaldehyde as an additive to generate nitrones in situ. Our control experiments indicate that nitrones and water were indispensable in the reactions whereas N-hydroxyanilines alone were inactive nucleophiles. This synthetic method is compatible with allene...

Aminoglycoside 2″-phosphotransferases are the major aminoglycoside-modifying enzymes in clinical isolates of enterococci and staphylococci. We describe a novel aminoglycoside 2″-phosphotransferase from the Gram-negative pathogen Campylobacter jejuni, which shares 78% amino acid sequence identity with the APH(2″)-Ia domain of the bifunctional aminoglycoside-modifying enzyme aminoglycoside (6') a...