solo
International Hazard
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Acylation of the amine group in Amino Acids....
It's been said in *March's text that the method to acylate Nh2 group in amino acids is to reflux with acidic anhydride and a strong base,
pyridine or sodium acetate( has been shown to work ). In order to protect the COOH from being acylated it's converted to an ester ( a simple
reflux in methanol with some HCl). Once the amino Acid has been acylated the protective ester can be **hydrolysed with a reflux in aqueous NaOH.
The question is can acylation be accomplished with refluxing the aminoacid ester with plain acetic acid in sodium acetate to get the same acylated
amino acid ester? Or is there another method with easier OTC materials?
REf.
*March's 5th ed. Pg.812. "replacement of a Carboxyl group by an acetyl grpup"
**Organic chemistry-McMurry 3rd. ed., Pg1058,"Peptide Synthesis"
Note : found this in the Archives of the Hive...
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psychokitty
Member posted 01-06-99 04:12 PM
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Here's my little contribution although I don't have the references with me presently to back it up:
Phenylalanine is either refluxed with formic acid under a dean-stark trap or mildly reacted with acetyl-chloride or acetic-anhydride to form the
formyl or acetyl amide, respectively. Then phenylalanine or any of the amides mentioned above are reduced with sodium borohydride and iodine in THF to
form the aminoalcohol or its N-alkylated version. Yes, you read right! In an analogue to the reduction of phenylalanine using sodium
borohydride/sulfuric acid formerly posted -- I think -- at the beginning of this thread, amides of phenylalanine are successfully reduced into their
respective N-alkylated aminoalcohols in about 85-95%, if I remember correctly. |
Ref:JOC 1993,58,3568-3571 "A Convenient Reduction of Amino Acids and Their Derivitives".
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A Convenient Reduction of Amino Acids and
Their Derivatives
Marc J. McKennon and A. I. Meyers'
J. Org. Chem. 1993,58, 3568-3571
Direct Link URL: http://home.ripway.com/2004-11/211899/AConvenientReductionof...
Short URL: http://h1.ripway.com/solo/AConvenientReductionofAminoAcidsan...
......from the text
Excerp
Reduction of N-Acyl-a-amino Acids
Since the earlier report using NaBH4-12 indicated that
carboxylic acids could be reduced to alcohols in the
presence of ester groups,9 we anticipated that the reduction of N-acylamino acids would lead to the formation of N-acylamino alcohols. Surprisingly,
the N-acyl group was completely reduced affording N-alkylamino alcohols as the only products.
Gee...I think I almost answered my own question......however in using a similar method to reduce the COOH to the OH one wonders if the folowing
method will also reduce the amide of the amino acid......
Transition Metal Compound Mediated Reduction of
-Amino Acids to 1,2-Amino Alcohols with NaBH4 in
Water
Ayhan S. DEM_IR, _Idris M. AKHMEDOV, ¨O. S ES ENO GLU
Turk J. Chem. (1999),23,2123-126
Direct Link URL: http://home.ripway.com/2005-1/247174/TransitionMetalCompound...
Short URL: http://h1.ripway.com/java/TransitionMetalCompoundMediatedRed...
Abstract
A new efficient and cost-effective method for the preparation of 1,2-amino alcohols is described.
The reactions of amino acids with NaBH4 in the presence of NiCl 2 or MoO3 in water give 1,2-amino alcohols in high yield. When optically pure amino
acids were used, optically pure 1,2-amino alcohols were obtained.
both methods will reduce the COOH to OH , the first documents it's effect on amides where's the second focuses on the COOH reduction but I
feel they both wil recude the amide to a primary amine ........any thoughts?........solo
[Edited on 26-11-2005 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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solo
International Hazard
Posts: 3967
Registered: 9-12-2002
Location: Estados Unidos de La Republica Mexicana
Member Is Offline
Mood: ....getting old and drowning in a sea of knowledge
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Well searching I found the classic method .....to methylate the amine group on the amino acid phenylalanine.....solo
The Action of Formaldehyde on Amines and Amino Acids'
BYH . T.C LARKEH, . B. GILLESPIAEN D S. 2. WEISSHAUS
JACS 55, 4571-4587, Nov. 1933.
http://rapidshare.de/files/8211760/The_Action_of_Formaldehyd...
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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