139481-69-9Relevant articles and documents
METHOD FOR PREPARING TRITYL CANDESARTAN
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Paragraph 0035, (2018/06/15)
The present invention uses a candesartan cyclic compound as a starting material and performs thereon a three-step reaction of forming tetrazole, hydrolysis and adding a protecting group to directly obtain trityl candesartan without separating an intermediate product via crystallization. The operating process is simple and thus is more applicable to industrial production.
PROCESS FOR PREPARATION OF CANDESART AN CILEXETIL SUBSTANTIALLY FREE OF DES-CANDESARTAN CILEXETIL IMPURITY
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Page/Page column 7, (2011/12/04)
The present invention provides a process for preparation of candeartan cilexetil substantially free of 2,3-dihydro-2-oxo-3-[[2'-(2H-tetrazol-5-yl)[l,l-biphenyl]-4- yl]methyl]-l-[[(cyclohexyloxy)carbonyl]oxy]ethylester-lH-benzimidazole-7- carboxylate (des-candesartan cilexetil) impurity.
METHOD FOR ISOLATING 5-SUBSTITUTED TETRAZOLES
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Page/Page column 4, (2009/08/18)
The invention relates to a method for isolating 5-substituted tetrazoles of general formula (I) in which R represents a substituted biphenyl radical during which the ring closure, starting from a corresponding nitrile, is carried out in organic solvents while using alkali, alkaline-earth or organotin azides. The organic phases containing the nitrile and the tetrazol are firstly mixed with water while firstly forming three liquid phases, after which the aqueous phase containing the azide and the phase containing the nitrile are separated out, and the middle organic phase containing the tetrazol is subsequently processed. In the case of ester groups to be saponified, this phase is mixed with alkali lye, after which the organic phase is separated out and the aqueous phase is acidified or otherwise, this phase is immediately acidified and purified.