ORGANIC
LETTERS
2000
Vol. 2, No. 3
397-399
Reduction of Azides to Amines
Mediated by Tin
Bis(1,2-benzenedithiolate)
Imma Bosch, Anna M. Costa, Manuel Mart´ın, Fe`lix Urp´ı,* and Jaume Vilarrasa*
Departament de Qu´ımica Orga`nica, Facultat de Qu´ımica, UniVersitat de Barcelona,
08028 Barcelona, Catalonia, Spain, EU
Received December 16, 1999
ABSTRACT
A procedure for the conversion of azides to amines, which uses NaBH and catalytic amounts of tin(IV) 1,2-benzenedithiolate, is disclosed.
4
Primary, secondary, tertiary, aromatic, and heteroaromatic azides are reduced in excellent yields under very mild conditions.
Reduction of azides to amines is a reaction of paramount
importance in organic synthesis; therefore, a great deal of
reagents have been reported to effect this transformation.1
In fact, there has been always considerable interest in
searching for more efficient and chemoselective azide-
reducing agents.2
Years ago we reported on new tin(II) complexes of the
general formula [Et3NH][Sn(SR)3],3 which reduce azides and
nitro compounds but not carbonyl groups. Azides, even the
most hindered ones, react completely within a few minutes
at room temperature in a plethora of solvents, to afford
amines in practically quantitative yields. These tin reagents
can be readily obtained (i) by adding RSH and Et3N to
insoluble, polymeric Sn(SR)2,3a,b (ii) by mixing SnCl2, RSH,
and Et3N in a 1:3:3 ratio,3c and (iii) by treating phos-
(1) Reviews: (a) Marson, C. M.; Hobson, A. D. In ComprehensiVe
Organic Functional Group Transformations; Ley, S. V., Ed.; Pergamon-
Elsevier: Oxford, U.K., 1995; Vol. 2, p 297. (b) Gilchrist, T. L. In
ComprehensiVe Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
Pergamon: Oxford, U.K., 1991; Vol. 8, p 381. (c) Hassner, A. In Houben-
Weyl Methods of Organic Chemistry, 4th ed.; Georg-Thieme Verlag:
Stuttgart, Germany, 1990; Vol. E16a, Part 2, p 1243. (d) Scriven, E. F. V.;
Turnbull, K. Chem. ReV. 1988, 88, 298.
(2) For methods reported in the last 5 or 6 years, see the following. (a)
NaBH4/CuSO4: Rao, H. S. P.; Siva, P. Synth. Commun. 1994, 24, 549. (b)
Zn(BH4)2: Ranu, B. C.; Sarkar, A.; Chakraborty, R. J. Org. Chem. 1994,
59, 4114. (c) Aminoborohydrides: Alvarez, S. G.; Fisher, G. B.; Singaram,
B. Tetrahedron Lett. 1995, 36, 2567. (d) HBCl2: Salunkhe, A. M.; Brown,
H. C. Tetrahedron Lett. 1995, 36, 7987. (e) Hexamethyldisilathiane:
Capperucci, A.; Innocenti, A. D.; Funicello, M.; Mauriello, G.; Scafato,
P.; Spagnolo, P. J. Org. Chem. 1995, 60, 2254. (f) SmI2: Benati, L.;
Montevecchi, P. C.; Manni, D.; Spagnolo, P.; Volta, M. Tetrahedron Lett.
1995, 36, 7313. (g) SmI2: Goulaouic-Dubois, C.; Hesse, M. Tetrahedron
Lett. 1995, 36, 7427. (h) Tetrathiomolybdate ion: Ramesha, A. R.; Bhat,
S.; Chandrasekaran, S. J. Org. Chem. 1995, 60, 7682. (i) Fe/NiCl2: Baruah,
M.; Boruah, A.; Prajapati, D.; Sandhu, J. S.; Chosh, A. C. Tetrahedron
Lett. 1996, 37, 4559. (j) Fe/NH4Cl: Cho, S.-D.; Choi, W.-Y.; Lee, S.-G.;
Yoon, Y.-J.; Shin, S. C., Tetrahedron Lett. 1996, 37, 7059. (k) H2S/pyr:
Inoue, I.; Saneyoshi, M.; Adachi, T.; Yamada, Y. Synthesis 1997, 45. (l)
Zn/NiCl2: Boruah, A.; Baruah, M.; Prajapati, D.; Sandhu, J. S. Synlett 1997,
1253. (m) Sm/I2: Huang, Y.; Zhang, Y.; Wang, Y. Tetrahedron Lett. 1997,
38, 1065. (n) Baker’s yeast: Kamal, A.; Laxminarayana, B.; Gayatri, N.
L. Tetrahedron Lett. 1997, 38, 6871. (o) TMSCl/NaI: Kamal, A.; Rao, N.
V.; Laxman, E. Tetrahedron Lett. 1997, 38, 6945. (p) Bu3SnH-catalyzed:
Hays, D. S.; Fu, G. C. J. Org. Chem. 1998, 63, 2796. (q) In/NH4Cl: Reddy,
G. V.; Rao, G. V.; Iyengar, D. S. Tetrahedron Lett. 1999, 40, 3937. (r)
MCM-silylamine-Pd complex/H2: Kantam, M. L.; Chowdari, N. S.;
Rahman, A.; Choudary, B. M. Synlett 1999, 1413. (s) Organouranium
complexes/H2: Peters, R. G.; Warner, B. P.; Burns, C. J. J. Am. Chem.
Soc. 1999, 121, 5585.
(3) (a) Bou, V. Master Thesis, Universitat de Barcelona, 1987. (b) Bartra,
M.; Urp´ı, F.; Vilarrasa, J. Tetrahedron Lett. 1987, 28, 5941. (c) Bartra, M.;
Bou, V.; Garcia, J.; Urp´ı, F.; Vilarrasa, J. J. Chem. Soc., Chem. Commun.
1988, 270. (d) Bartra, M.; Romea, P.; Urp´ı, F.; Vilarrasa, J. Tetrahedron
1990, 46, 587. (e) Bosch, I. Master Thesis, Universitat de Barcelona, 1992.
(f) For remarkable applications of the SnII/PhSH complex in the field of
natural products, see: Nicolaou, K. C.; Caulfield, T. J.; Kataoka, H.;
Stylianides, N. A. J. Am. Chem. Soc. 1990, 112, 3693. Forrest, A. K.;
O’Hanlon, P. J.; Walker, G. Tetrahedron 1994, 50, 19739. Kick, E. K.;
Ellman, J. A. J. Med. Chem. 1995, 38, 1427. Urban, D.; Skrydstrup, T.;
Riche, C.; Chiaroni, A.; Beau, J.-M. J. Chem. Soc., Chem. Commun. 1996,
1883. Lee, C. E.; Kick, E. K.; Ellman, J. A. J. Am. Chem. Soc. 1998, 120,
9735. Urban, D.; Skrydstrup, T.; Beau, J.-M. J. Org. Chem. 1998, 63, 2507.
Lee, J. W.; Fuchs, P. L. Org. Lett. 1999, 1, 179.
10.1021/ol991359z CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/20/2000