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Author: Subject: von Braun Cyanogen Bromide Reaction alternative
Mush
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[*] posted on 28-5-2018 at 03:20
von Braun Cyanogen Bromide Reaction alternative


I'm looking for an alternative to von Braun Cyanogen Bromide reaction , that uses less/non toxic reagents.

I've found an alternative option (Comprehensive Organic Functional Group Transformations, Volume 6, p444) but it utilizes phosgene what is even more toxic.
von Braun phosgene.png - 103kB
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Chemi Pharma
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[*] posted on 28-5-2018 at 04:50


The only know (by me) alternative to do this kind of N-dealkylation is using alkyl or aryl chloroformates, which are all as toxic as BrCN, followed by heating with methyl alcohol at reflux.





[Edited on 28-5-2018 by Chemi Pharma]
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[*] posted on 28-5-2018 at 07:54


Quote: Originally posted by Chemi Pharma  
The only know (by me) alternative to do this kind of N-dealkylation is using alkyl or aryl chloroformates, which are all as toxic as BrCN, followed by heating with methyl alcohol at reflux.
[Edited on 28-5-2018 by Chemi Pharma]


Thanks! I've just found this article based on your advice.

New, Useful Reactions of Novel Haloformates and Related Reagents
Article in Pure and Applied Chemistry 60(11):1715-1724 · January 1988 
N-demethylation with haloformates.png - 135kB
Attachment: 10.1.1.567.5857_New, useful reactions of novel haloformates.pdf (792kB)
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See also :
A new reagent for the selective, high-yield N-dealkylation of tertiary amines: improved syntheses of naltrexone and nalbuphine
R. A. Olofson, Jonathan T. Martz, Jean Pierre Senet, Marc Piteau, and Thierry Malfroot
J. Org. Chem., 1984, 49 (11), pp 2081–2082
DOI: 10.1021/jo00185a072
Publication Date: June 1984

[Edited on 28-5-2018 by Mush]
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Chemi Pharma
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[*] posted on 28-5-2018 at 11:17


Thank you either @Mush for the paper.

I didn't know acetaldehyde, phosgene and catalytic PTC with chloride ion afford alfa chloroethyl chloroformate, which is really an useful reagent.

Do you think the easier to achieve tert butil ammonium chloride (TBAC) could be used instead PhCH2N(nBu)3Cl (BTBAC), in this synthesis ?

Edited: TBAC - tetra butyl ammonium chloride, no tert butil. I apologize. Thanks @Outer for the correction. Tert butyl alcohol were in my head.

[Edited on 28-5-2018 by Chemi Pharma]
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[*] posted on 28-5-2018 at 12:29


TBAC is tetra butyl ammonium chloride, and not tert-butyl ammonium chloride. Yes, it can be tried as well.
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[*] posted on 14-1-2019 at 16:18


New Methodology for the N-Demethylation of Opiate Alkaloids
Zemin Dong, and Peter J. Scammells*
Department of Medicinal Chemistry, Victorian College of Pharmacy, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
J. Org. Chem., 2007, 72 (26), pp 9881–9885
DOI: 10.1021/jo071171q

Tetrasodium 5,10,15,20-tetra(4-sulfophenyl)-porphyrinatoiron(II)


jo071171qn00001.gif - 13kB

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