58258-01-8Relevant articles and documents
Electrochemical: N -demethylation of tropane alkaloids
Alipour Najmi, Ali,Bischoff, Rainer,Dekker, Frank J.,Permentier, Hjalmar P.,Xiao, Zhangping
supporting information, p. 6455 - 6463 (2020/11/09)
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.
A biocatalytic/reductive etherification approach to substituted piperidinyl ethers
Kuethe, Jeffrey T.,Janey, Jacob M.,Truppo, Matthew,Arredondo, Juan,Li, Tao,Yong, Kelvin,He, Shuwen
, p. 4563 - 4570 (2014/06/10)
A synthetically useful protocol has been developed for the preparation of highly functionalized piperidinyl ethers. Biocatalytic reduction of cyclhexanones 7, 10, and 14 allows for the preparation of both cis- and trans diastereomers with an extremely high degree of stereochemical control. Reductive etherification of the corresponding trimethylsilylethers with 1-(benzyloxycarbonyl)-4-piperidinone 17 in the presence of triethylsilane and catalytic TMSO-Tf provides the desired piperidinyl ethers in good to excellent yields. Finally hygrogenolysis of the nitrogen protecting group leads to piperidinyl ethers in near quantitative yields. Application of the methodology to a range of piperidinyl ethers, including the core scaffolds of diphenylpyraline and ebastine, is also described.
Process for the preparation of 1-[4-(1,1-dimethylethyl)phenyl]-4-[4-(diphenylmethoxy)-1-piperidinyl]-1-butanone and acid addition salts thereof
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Page/Page column 25-26, (2011/10/13)
The present invention describes processes for the preparation of 1-[4-(1,1-dimethylethyl)phenyl]-4-[4-(diphenylmethoxy)-1-piperidinyl]-1-butanone and acid addition salts thereof.
