Enantioselective Alkynylation Reactions to Substituted Benzaldehyde and Salicylaldehyde Derivatives: The Effect of Substituents upon the Efficiency and Enantioselectivity
Asymmetric alkynylation reactions to mono-, di-, and trisubstituted aromatic aldehydes have been accomplished in good yields and with a range of selectivities. For salicylaldehyde derivatives both the yield and the enantioselectivity of the alkynylation reaction appears to depend not only upon the electron-donating/ electron-withdrawing nature of substituents but also upon their position in the ring
Asymmetric alkynylation reactions to linear alkyl and substituted aromaticaldehydes have been accomplished in good yields and with a range of selectivities. For aromaticaldehydes we observed that the selectivity of the alkynylation reaction appears to depend upon the substituents on the aromatic ring. Thus with electron-withdrawing substituents both the yield and enantioselectivities were good to
O-Prenylated aromatic aldehydes undergo smooth intramolecular dominoKnoevenagelhetero-Diels-Alderreactions with 4-hydroxycoumarins in the air- and moisture-stable ionic liquid [bmim[BF 4 under mild conditions to afforda novel class of cis-annulated pyranocoumarins in high yields. The recovered ionic liquid can be reused in successive runs with consistent activity.
Bis-pyranobenzoquinones as a New Family of Reversal Agents of the Multidrug Resistance Phenotype Mediated by P-Glycoprotein in Mammalian Cells and the Protozoan Parasite <i>Leishmania</i>
作者:Sandra Jiménez-Alonso、Antonio L. Pérez-Lomas、Ana Estévez-Braun、Francisco Muñoz Martinez、Haydee Chávez Orellana、Angel G. Ravelo、Francisco Gamarro、Santiago Castanys、Matías López
DOI:10.1021/jm800403b
日期:2008.11.27
We have synthesized a set of bis-pyranobenzoquinones through a direct and highly efficient approach based on a double intramolecular domino Knoevenagel hetero Diels-Alder reaction. These bis-pyranobenzoquinone derivatives are compounds whose skeletons have similarities to those of some anticancerous and leishmanicidal drugs. Considering that these drugs are substrates for some members of the ATP-binding cassette (ABC) family of proteins that confers a multidrug resistance (MDR) phenotype, we have carried out the biological evaluation of 20 bis-pyranobenzoquinones as modulators of the MDR phenotype in mammalian cell lines overexpressing P-glycoprotein, MRP1, or BCRP. Moreover, we also tested some of these compounds as potential MDR modulators in a Leishmania tropica line overexpressing a P-glycoprotein-like transporter. Compounds 9 and 10 are, in this work, the most promising reversal agents of MDR in human cancer cell lines, while compounds 4 and 20 showed potent reversal activity of MDR phenotype in the protozoan parasite Leishmania.
Intra- and intermolecular hetero-Diels-Alder reactions. 17. Intramolecular hetero-Diels-Alder reaction of alkylidene- and benzylidenepyrazolones and benzylideneisoxazolones. Investigations toward the conformation of the transition state
作者:Lutz F. Tietze、Thomas Brumby、Martina Pretor、Gerd Remberg