- Synthesis of (nor)tropeine (di)esters and allosteric modulation of glycine receptor binding
-
(Hetero)aromatic mono- and diesters of tropine and nortropine were prepared. Modulation of [3H]strychnine binding to glycine receptors of rat spinal cord was examined with a ternary allosteric model. The esters displaced [3H]strychnine binding with nano- or micromolar potencies and strong negative cooperativity. Coplanarity and distance of the ester moieties of diesters affected the binding affinity being nanomolar for isophthaloyl-bistropane and nortropeines. Nortropisetron had the highest affinity (KA ~ 10 nM). Two esters displayed negative cooperativity with glycine in displacement, while three esters of low-affinity and nortropisetron exerted positive cooperativity with glycine.
- Maksay, Gabor,Nemes, Peter,Vincze, Zoltan,Biro, Timea
-
-
Read Online
- Electrochemical: N -demethylation of tropane alkaloids
-
A practical, efficient, and selective electrochemical N-demethylation method of tropane alkaloids to their nortropane derivatives is described. Nortropanes, such as noratropine and norscopolamine, are important intermediates for the semi-synthesis of the medicines ipratropium or oxitropium bromide, respectively. Synthesis was performed in a simple home-made electrochemical batch cell using a porous glassy carbon electrode. The reaction proceeds at room temperature in one step in a mixture of ethanol or methanol and water. The method avoids hazardous oxidizing agents such as H2O2 or m-chloroperbenzoic acid (m-CPBA), toxic solvents such as chloroform, as well as metal-based catalysts. Various key parameters were investigated in electrochemical batch or flow cells, and the optimized conditions were used in batch and flow-cells at gram scale to synthesize noratropine in high yield and purity using a convenient liquid-liquid extraction method without any need for chromatographic purification. Mechanistic studies showed that the electrochemical N-demethylation proceeds by the formation of an iminium intermediate which is converted by water as the nucleophile. The optimized method was further applied to scopolamine, cocaine, benzatropine, homatropine and tropacocaine, showing that this is a generic way of N-demethylating tropane alkaloids to synthesize valuable precursors for pharmaceutical products.
- Alipour Najmi, Ali,Bischoff, Rainer,Dekker, Frank J.,Permentier, Hjalmar P.,Xiao, Zhangping
-
p. 6455 - 6463
(2020/11/09)
-
- Contra-thermodynamic Hydrogen Atom Abstraction in the Selective C-H Functionalization of Trialkylamine N-CH3 Groups
-
We report a simple one-pot protocol that affords functionalization of N-CH3 groups in N-methyl-N,N-dialkylamines with high selectivity over N-CH2R or N-CHR2 groups. The radical cation DABCO+?, prepared in situ by oxidation of DABCO with a triarylaminium salt, effects highly selective and contra-thermodynamic C-H abstraction from N-CH3 groups. The intermediates that result react in situ with organometallic nucleophiles in a single pot, affording novel and highly selective homologation of N-CH3 groups. Chemoselectivity, scalability, and recyclability of reagents are demonstrated, and a mechanistic proposal is corroborated by computational and experimental results. The utility of the transformation is demonstrated in the late-stage site-selective functionalization of natural products and pharmaceuticals, allowing rapid derivatization for investigation of structure-activity relationships.
- Barham, Joshua P.,John, Matthew P.,Murphy, John A.
-
supporting information
p. 15482 - 15487
(2016/12/09)
-
- The synthesis of anticholinergically active N-alkylnorscopolamines and their quaternary salts with particular consideration of the bronchospasmolytic compound (-)-N-ethylnorscopolamine methobromide (Ba 253 BR)
-
The synthesis of anticholinergic N-alkylnorscopolamines and their quaternary salts, especially the synthesis of (-)-N-ethylnorscopolamine methobromide (Ba 253 BR), is reported. (-)-N-Ethylnorscopolamine methobromide differs from the stereoisomeric (-)-N-ethylscopolammonium bromide not only by its physico-chemical, but also by its pharmacological properties. (-)-N-Ethylnorscopolamine methobromide represents an anticholinergic bronchodilator with long duration of action.
- Banholzer,Pook
-
p. 217 - 228
(2007/10/02)
-