Development of small-molecule P-gp inhibitors of the N-benzyl 1,4-dihydropyridine type: Novel aspects in SAR and bioanalytical evaluation of multidrug resistance (MDR) reversal properties
Novel series of N-benzyl 1,4-dihydropyridines have been prepared by facilesyntheses. All relevant substituents of the molecular scaffold have been varied. The resulting compounds were biologically evaluated as P-glycoprotein (P-gp) inhibitors. Substitutions of the N-benzyl residue favour biological activity beside respective 3-ester functions. Most active compounds were further evaluated as multidrug
Aprotic pyridinium ions incorporating electron-withdrawing substituents on the aromatic ring are powerful catalysts for the acetalization of aldehydes and the formation of dithianes, dithiolanes, dioxanes, and dioxolanes. Under optimum conditions the best catalyst can be used at a loading as low as 0.1 mol% and can outperform a Brønsted acid catalyst with a pK a of 2.2.
含有吸电子取代基的非质子吡啶盐是醛的乙缩醛化反应以及二硫烷、二硫醇烷、二噁烷和二噁烷形成反应的强大催化剂。在最佳条件下,最佳催化剂的使用量可低至0.1 mol%,并能够胜过pK a 值为2.2的布朗斯特酸催化剂。
Diastereoselective trifunctionalization of pyridinium salts to access structurally crowded azaheteropolycycles
作者:Zhaohui Cui、Kuan Zhang、Lijie Gu、Zhanwei Bu、Junwei Zhao、Qilin Wang
DOI:10.1039/d1cc03478b
日期:——
A highly diastereoselective dearomative trifunctionalization of pyridinium salts with multifunctional o-hydroxy aromatic azomethine ylides has been established to assemble challenging and architecturally crowded fused pentacycles.
Asymmetric Hydrogenation of 3-Substituted Pyridinium Salts
作者:Marc Renom-Carrasco、Piotr Gajewski、Luca Pignataro、Johannes G. de Vries、Umberto Piarulli、Cesare Gennari、Laurent Lefort
DOI:10.1002/chem.201601501
日期:2016.7.4
equivalent amount of an organic base leads to high enantiomeric excess in the asymmetric hydrogenation of N‐benzylated 3‐substituted pyridiniumsalts into the corresponding piperidines. Indeed, in the presence of Et3N, a Rh‐JosiPhos catalyst reduced a range of pyridiniumsalts with ee values up to 90 %. The role of the base was elucidated with a mechanistic study involving the isolation of the various reaction
Catalytic enantioselective synthesis of 1,4-dihydropyridines <i>via</i> the addition of C(1)-ammonium enolates to pyridinium salts
作者:Calum McLaughlin、Jacqueline Bitai、Lydia J. Barber、Alexandra M. Z. Slawin、Andrew D. Smith
DOI:10.1039/d1sc03860e
日期:——
addition of C(1)-ammonium enolates – generated in situ from aryl esters and the isothiourea catalyst (R)-BTM – to pyridinium salts bearing an electron withdrawing substituent in the 3-position allows the synthesis of a range of enantioenriched 1,4-dihydropyridines. This represents the first organocatalytic approach to pyridine dearomatisation using pronucleophiles at the carboxylic acid oxidation level. Optimisation