ORGLIST: nitro vs. cyano group - summary

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From: Witek Mozga (mozga$##$trimen.pl)
Date: Sat May 19 2001 - 15:54:41 EDT



Dear members,

Thank you for all your replies.
For all of you interested in the topic I`ve prepared the summary of
responses I received:

====================================

From: DUFRASNE FRANCOIS <dufrasne$##$ulb.ac.be>

Dear Witek, you can find these methods:

Organic Synthesis: vol. 2 p. 447- / vol. 2 p. 501- / vol 2 471- 160- /
vol. 3 56- / vol. 2 p. 130- 254- / vol. 3 p. 239- 453-

These methods use metal in acidic medium, in tese conditions are cyano
groups not reduced.
--------------------------------------------------------------------

From: "Piotr Kwiatkowski" <pkwiat$##$icho.edu.pl>

Hello Witek
I suppose you want to reduce a nitro grup to an amino grup.
I have found a few various examples of selective reduction of a nitro
grup
in compounds as you described. You can find them in references:

J.Chem.Soc.; 1947; 1502; - Fe/HCl, 50 C
J.Med.Chem.; 34; 3; 1991; 1110-1116; -H2/Raney Ni, methanol, RT
Tetrahedron Lett.; 31; 48; 1990; 7003-7006; -H2/Pd/C, EtOH, RT
Chem.Pharm.Bull.; 36; 3; 1988; 1162-1168; -Zn powder, 2M HCl
J.Chim.Phys.Phys.Chim.Biol.; 93; 4; 1996; 601-610; -electrochemical
reduction
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From: "Ashutosh" <ashujo$##$yahoo.com>

You can try using HCOONH4-Pd-C?
This is given in Jerry March, 4th edition pg.1217.
-----------------------------------------------------

From: Gilbert KIRSCH <kirsch$##$sciences.univ-metz.fr>

Hi,
Some aliphatic (cyclohexyl)nitro compounds have been reduced using
iron in acetic acid or smooth hydrogenation
conditions.See:Nielsen,J.Org.Chem.,1962,27,1998
-------------------------------------------------------

From: "Giuseppe Mangano"
<Giuseppe.Mangano$##$ico.unil.ch>

You can dissolve your nitrocompound in HCl conc. and after you add
with little portion, Sn, under stirring in an Erlenmeyer flask or Pd/C
(10%) with H2 (1 atm) in ethanol at 25C under stirring in a Schlenk flask
taking care to eliminate completely oxygen before
-----------------------------------------------------------

From: chewitt$##$sial.com

Two of our scientists have made the following suggestions:

Firstly

One of the following references should be able to help in getting the job
      done either directly or indirectly. All tolerate various functional
      groups very well.

a) JACS 1951, 73, 1293 b) Syn. Commun. 1990, 20, 459 c. JACS 1992,
114, 10181. d) TL 1987, 28, 577.


Secondly

M. Couturier from Pfizer developed a methodology using less reactive
amine-boranes as hydrogenating reagents in the presence of catalytic
amounts of Pd/C. (See Tet. Lett., 2001, 42, 2763 and Org. Lett., 2001, 3,
465). Hydrogenation is the only technique that can differentiate NO2
group from CN during reductions. This amine-borane based methodology
seems to be more selective.
------------------------------------------------------------

From: antonio regla <areglac$##$yahoo.com>

I have been doing some searching on reduction of an n-nitroso group to an
n-amino group, and thought about your question on nitro groups. There are
references on reduction of aliphatic nitro groups on Organic Synthesis
coll. vol.2, which may be of interest for you to try. I was looking for an
example of a compound containing cyano and nitro groups and couldn't find
any there, however the hydrogenation conditions for cyano containing
compounds seem a lot harsher than those for nitro groups, it may be
worthwhile giving it a look.
------------------------------------------------------------
From: Stephan Bird <pcxsjb1.Nb$##$nottingham.ac.uk>

Not too sure about the wider scope of the reaction, but CoCl2.6H2O, at low
temps was reported to reduce ArNO2 with Alk-CN present... the ref is in
the first edition of Larock, for one. Looking through March, it seems
boranes might be the way to go..?


Witek
http://www.trimen.pl/witek/



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