The above two articles are now available in HTML at my page:
Reduction of Azides to Amines or Amides with Zinc and Ammonium Chloride as Reducing Agent
W. Lin, X. Zhang, Z. He, Y. Jin, L. Gong, A. Mi
Synthetic Communications 32(21), 3279 (2002) (https://www.thevespiary.org/rhodium/Rhodium/chemistry/azide2amine.zn-nh4cl.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/azide2amine.zn-nh4cl.html)
Abstract
Alkyl azides and acyl azides were reduced to the corresponding amines and amides with zinc and ammonium chloride as reducing agent under mild conditions in good to excellent yield.
____ ___ __ _
Zinc/ammonium formate: a new facile system for the rapid and selective reduction of oximes to amines
K. Abiraj and D. Channe Gowda
Journal of Chemical Research (Synopses) 6, 332-334 (2003) (https://www.thevespiary.org/rhodium/Rhodium/chemistry/oxime2amine.zn-af.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/oxime2amine.zn-af.html)
Abstract
Various oximes, both aldoximes and ketoximes, are selectively reduced to corresponding amines employing low cost zinc dust and ammonium formate despite presence of other functional groups such as halogens, -OH, -OCH3, -COOH, -CN, >C=C< and -CH3.
This is reference 8 from endo1's post above. The excess of reagents, along with the use of anhydrous THF, is probably overkill. The above, more recent, reduction system uses only a slight excess of zinc, and is tolerant of water.
The Effective Chemoselective Reduction of Azides to Primary Amines
Anima Boruah, Mukulesh Baruah, Dipak Prajapati and Jagir S. Sandhu*
Synlett, 1997, 1253-1254
Abstract
Reduction of azides to amines or amides occurs in excellent yields upon treatment with a novel reduction system consisting of Zn-NiCl2*6H2O-THF
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
Although the experimental from reference 5b in endo1's post is archived at Synthesis and Reduction of Azides (https://www.thevespiary.org/rhodium/Rhodium/chemistry/azide.rxns.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/azide.rxns.html), the full paper demonstrates the excellent selectivity of the method:
Cobalt(II) Chloride-Catalyzed Chemoselective Sodium Borohydride Reduction of Azides in Water
Francesco Fringuelli, Ferdinando Pizzo,* Luigi Vaccaro
Synthesis, 2000 (5), 646-650
Abstract
Reduction of azides to amines and amides was carried out with NaBH4/CoCl2•6H2O in sole water at 25°C under catalytic heterogeneous conditions. A broad spectrum of azides was reduced in a short time, chemoselectively in high yield and purity.
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
This is reference 10, the reduction of azides with Fe/NH4Cl:
Chemoselective Reduction of Highly-functionalized Azidopyridazines to Corresponding Aminopyridazines Using Fe/NH4Cl in Organic Solvent-Water Two-phase Solution
Su-Dong Cho, Woo-Yong Choi, Sang-Gyeong Lee, Yong-Jin Yoon*, and Sung Chul Shin*
Tetrahedron Letters, 37 (39), 7059-7060, 1996
Abstract
Highly functionalized azidopyridazines can be reduced chemoselectively to the corresponding amines in excellent yields.
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
HI is remarkably selective under certain conditions, and can be used to reduce azides to amines:
Simple and facile reduction of azides to amines: synthesis of DNA interactive pyrrolo[2,1-c][1,4]benzodiazepines
Ahmed Kamal,* P. S. M. M. Reddy and D. Rajasekhar Reddy
Tetrahedron Letters, 43 (2002), 6629–6631
Abstract
The reduction of aromatic azido compounds to the corresponding amines with hydriodic acid has been investigated andfound to result in high yields. This reductive methodology which proceeds under non refluxing condition has been extended for the synthesis of DNA-interactive pyrrolo[2,1-c][1,4] benzodiazepine antibiotics.
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
Finally, here is a route to make alkyl azides from alkyl halides, similar to the method used by Ritter in MDA from Bromosafrole Using a PTC and an Azide Intermediate (https://www.thevespiary.org/rhodium/Rhodium/chemistry/mda.azide.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/mda.azide.html):
Phase Transfer Catalysis; Preparation of Alkyl Azides
W. Preston Reeves, Martin L. Bahr
Synthesis, 1976, 823
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
Yet another great article from India, referenced in the CoCl2/NaBH4 reduction of azides posted above:
Facile Reduction of Azides with Sodium Borohydride/Copper (II) Sulfate System
H. Surya Prakash Rao* and P. Siva
Synthetic Communications, 24(4), 549-555 (1994)
Abstract
Sodium borohydride/copper (II) sulfate reduces alkyl and aryl azides to primary amines and aroyl azides to amides under mild conditions.
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
This was a reference from the above paper, which deserves its own post: look what else this system is capable of!
Reduction of Organic Compounds with Sodium Borohydride-Copper Sulfate (II) System
Sung-eun Yoo*, Sang-hee Lee
Synthesis, 1990, 419-420
Abstract
The reduction of various groups was investigated using sodium borohydride-copper (II) sulfate. Ketones, aliphatic esters, olefins, nitriles and aliphatic and aromatic nitro groups were reduced, but amides, aliphatic and aromatic carboxylic acids were inert. Rate of reaction was different for the various functional groups, allowing selective reductions to be peformed.
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
Edit: Here's a bonus article, as the CuSO4-NaBH4 system doesn't reduce carboxylic acids or amides to their respective alcohols or amines. For this, and for high-yielding reductions of oximes to amines (for which it is referenced in Post 54080 (https://www.thevespiary.org/talk/index.php?topic=9541.msg5408000#msg5408000)
(Sonson: "High-yielding synthesis of MDA from MDP2P", Methods Discourse)), TiCl4-NaBH4 can be used:
Reduction of Some Functinal Groups with Titanium (IV) Chloride/Sodium Borohydride
Shinzo Kano, Yasuyuki Tanaka, Eiichi Sugino, Satoshi Hibino
Synthesis, 1980, 695-697
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
Here are two more high-yielding reductions of azides. The first looks similar to a quote by from Total Synthesis II, posted by psyloxy in Post 108887 (missing)
(psyloxy: "Re: Sodium Azide route", Novel Discourse):
Facile Conversion of Azides to Amines
Samarendra N. Maiti, Maya P. Singh and Ronald G. Micetich
Tetrahedron Letters, 27(13), 1423-1424, 1986
Summary
A simple method for the reduction of azides to primary amines is described
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)
The second article uses a simple CTH method for the azide to amine reduction:
Reduction D'Azides En Amines Par Le Formiate D'Ammonium Par ''Transfert D'Hydrogene Catalyse'' (CTH)
T. Gartiser, C. Selve* et J.-J. Delpuech
Tetrahedron Letters, 24(15), 1609-1610, 1983
Summary
The azides are reduced to amines in very good yields by ''Catalytic Transfer Hydrogenation'' (CTH) using ammonium formate
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/pdf.gif)