Isolation of the antibiotic pseudopyronine B and SAR evaluation of C3/C6 alkyl analogs
作者:Leah M. Bouthillette、Catherine A. Darcey、Tess E. Handy、Sarah C. Seaton、Amanda L. Wolfe
DOI:10.1016/j.bmcl.2017.04.067
日期:2017.6
for antibacterial activity againstGram-positive and Gram-negative bacteria. We found a direct relationship between antibacterial activity and C3/C6 alkyl chain length. For inhibition of Gram-positive bacteria, alkyl chain lengths between 6 and 7 carbons were found to be the most active (IC50=0.04-3.8µg/mL) whereas short alkyl chain analogs showed modest activity against Gram-negative bacteria (IC50=223-304µg/mL)
Regioselective C-alkylations at the intercarbonyl positions C-4 and C-2 of the polyketide model methyl 3,5-dioxohexanoate, 1, have been acomplished through reactions of its cobalt(II), 4a, and copper(II), 4b, complexes respectively. Some examples of double alkylations at both positions are presented. Cyclizations of the regioselectively substituted diketoesters so prepared gave triacetic acid lactone
Copper complex protection in the regioselective alkylation of methyl 3,5-dioxohexanoate. Preparation of 3-alkyl derivatives of 4-hydroxy-6-methyl-2-pyrone
Protection of the diketone moiety of the polyketide model methyl 3,5-dioxohexanoate by copper(II) complex formation followed by alkylation of the free C-2 position results in overall regioselectivealkylation of the diketoester to afford methyl 2-alkyl-3,5-dioxohexanoates, which under cyclization afford 3-alkyl derivatives of triacetic acid lactone.
A simple and effective method for the reduction of acyl substituted heterocyclic 1,3-dicarbonyl compounds to alkyl derivatives by zinc - acetic acid - hydrochloric acid
3-Acyl-4-hydroxy-2(1H)-quinolones (1a–k) were reduced in good yields (66–97%) to 3-alkyl-4-hydroxy-2(1H)-quinolinones (2a–k) using zinc powder (particle size <45 μm) in acetic acid/hydrochloric acid. This method could be transformed to 3-acetyl-4-hydroxy-coumarin (1l), 3-acetyl-4-hydroxy-2-pyranone (3a) and 3-acetyl-4-hydroxy-2(1H)-pyridinone (3b), which yielded the 3-ethyl derivatives 2l, 4a and 4b, respectively
Iridium catalyzed acceptor-less dehydrogenative coupling of alcohols and 4-hydroxy-6-methyl-2-pyrone under microwave conditions
作者:Mitchell Proud、Visuvanathar Sridharan
DOI:10.1016/j.tetlet.2015.10.034
日期:2015.11
Iridium catalyzed acceptor-less dehydrogenative coupling of benzyl type alcohols and 4-hydroxy-6-methyl-2-pyrone under microwave conditions afforded 3,3'-(arylmethylene)bis(4-hydroxy-6-methyl-2H-pyran-2-ones) in good yields. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.