AlCl<sub>3</sub>-Mediated Direct Carbon−Carbon Bond-Forming Reaction of α-Hydroxyketene-<i>S</i>,<i>S</i>-acetals with Arenes and Synthesis of 3,4-Disubstituted Dihydrocoumarin Derivatives
作者:Cheng-Ri Piao、Yu-Long Zhao、Xiao-Dan Han、Qun Liu
DOI:10.1021/jo702414y
日期:2008.3.1
α-hydroxyketene-S,S-acetals and various arenes via direct substitution of the hydroxy group in alcohols has been developed. On the basis of this C−C coupling reaction, a series of bio- and pharmacologically important 3,4-disubstituted dihydrocoumarins, difficult to obtain by other methods, were prepared in high yields by a sequential Friedel−Crafts alkylation and intramolecular annulation reaction of α-hydroxyketene
Asymmetric hydrogenation of esters through homogeneous catalysis is a significantly important transformation in organic synthesis. The systems developed so far mainly focused on chiral iridium and ruthenium catalysts, which required a base to facilitate the activity. Herein, we present a palladium-catalyzed asymmetric hydrogenation of lactones under base-free conditions through dynamic kinetic resolution
Inhibitors of Sir2: Evaluation of Splitomicin Analogues
作者:Jeff Posakony、Maki Hirao、Sam Stevens、Julian A. Simon、Antonio Bedalov
DOI:10.1021/jm030473r
日期:2004.5.1
Splitomicin (1) and 41 analogues were prepared and evaluated in cell-based Sir2 inhibition and toxicity assays and an in vitro Sir2 inhibition assay. Lactone ring or naphthalene (positions 7-9) substituents decrease activity, but other naphthalene substitutions (positions 5 and 6) are well-tolerated. The hydrolytically unstable aromatic lactone is important for activity. Lactone hydrolysis rates were used as a measure of reactivity; hydrolysis rates correlate with inhibitory activity. The most potent Sir2 inhibitors were structurally similar to and had hydrolysis rates similar to 1.
The Reaction between Methylated Quinones and Sodium Enolates. VIII. Mechanism. The Addition of Sodium Malonic Ester to a Methylene Quinone<sup>1</sup>