M. Petrini, E. Torregiani / Tetrahedron Letters 47 (2006) 3501–3503
7. Petrini, M. Chem. Rev. 2005, 105, 3949–3977.
3503
NH2
NHCHO
NO2
8. (a) Xu, X.; Furukawa, T.; Okino, T.; Miyabe, H.;
Takemoto, Y. Chem. Eur. J. 2006, 12, 466–476; (b)
Bernardi, L.; Fini, F.; Herrera, R. P.; Ricci, A.; Sgarzani,
V. Tetrahedron 2006, 62, 375–380; (c) Palomo, C.;
1. SmI2 THF-MeOH
2. HCl, MeOH
70%
NH2
3b
4
´
Oiarbide, M.; Halder, R.; Laso, A.; Lopez, R. Angew.
Chem., Int. Ed. 2005, 44, 117–120; (d) Jacobsen, E. N.;
Yoon, T. P. Angew. Chem., Int. Ed. 2005, 44, 466–468; (e)
Nugent, B. M.; Yoder, R. A.; Johnston, J. N. J. Am.
Chem. Soc. 2004, 126, 3418–3419.
Scheme 3.
NHCHO
OHCHN
9. (a) Petrini, M.; Seri, M. Tetrahedron 2006, 62, 960–967; (b)
Bu3SnH, AIBN
C6H6, reflux 1h
NO2
´
Palomo, C.; Oiarbide, M.; Laso, A.; Lopez, R. J. Am.
Chem. Soc. 2005, 127, 17622–17623; (c) Fini, F.; Sgarzani,
V.; Pettersen, D.; Herrera, R. P.; Bernardi, L.; Ricci, A.
Angew. Chem., Int. Ed. 2005, 44, 7975–7978; (d) Foresti,
E.; Palmieri, G.; Petrini, M.; Profeta, R. Org. Biomol.
Chem. 2003, 1, 4275–4281; (e) Ballini, R.; Petrini, M.
Tetrahedron Lett. 1999, 40, 4449–4452.
R
R
3l R = H
3m R = p-MeOC6H4
5a R = H, 80%
5b R = p-MeOC6H4, 84%
Scheme 4.
10. Greene, T. W.; Wuts, P. G. M. Protective Groups in
Organic Synthesis; Wiley: New York, 1999.
checked on a couple of tertiary N-formylamido nitro
derivatives 3l,m, which upon heating in a benzene solu-
tion in the presence of 2 equiv of Bu3SnH and a catalytic
amount of a radical initiator (AIBN) give the corre-
sponding formylamides 5 in good yield (Scheme 4).
11. (a) Liu, H.; Zhang, H.-L.; Wang, S.-J.; Mi, A.-Q.; Jiang,
Y.-Z.; Gong, L.-Z. Synlett 2005, 615–618; (b) Zhang,
H.-L.; Liu, H.; Cui, X.; Mi, A.-Q.; Jiang, Y.-Z.; Gong,
L.-Z. Tetrahedron: Asymmetry 2005, 16, 2901–2907; (c)
Rossen, K.; Jakubec, P.; Kiesel, M.; Janik, M. Tetra-
hedron Lett. 2005, 46, 1819–1821; (d) Frantz, D. G.;
Morency, L.; Soheili, A.; Murry, J.; Grabowski, E. J. J.;
Tillyer, R. D. Org. Lett. 2004, 6, 843–846; (e) Dahmen, S.;
Bra¨se, S. J. Am. Chem. Soc. 2002, 124, 5940–5941; (f)
Hermanns, N.; Dahmen, S.; Bolm, C.; Bra¨se, S. Angew.
Chem., Int. Ed. 2002, 41, 3692–3694.
In conclusion, N-formylaryl sulfones 1 promptly react
with nitroalkanes 2 in the presence of NaH giving the
corresponding aza-Henry adducts 3 in good yield and
high anti-diastereoselectivity. Reduction of the nitro
group and hydrolysis of the formyl protection from N-
formylamido nitro derivatives 3 provide an entry to
1,2-diamino derivatives. Products 3 obtained by reaction
of secondary nitroalkanes are particularly prone to
radical induced reduction that allows the preparation
of denitrated product 5.
12. Sisko, J.; Mellinger, M.; Sheldrake, P. W.; Baine, N. H.
Tetrahedron Lett. 1996, 37, 8113–8116.
13. General procedure for aza-Henry reaction on N-formyl-
aryl sulfones 1: To
a stirred suspension of NaH
(3.0 mmol) in dry THF (15 mL) the appropriate nitro-
alkane 2 (1.5 mmol) was added at room temperature.
After stirring for 30 min, sulfone 1 (1.0 mmol) dissolved in
dry THF (5 ml) was added dropwise and the white
suspension was stirred for 45 min at room temperature.
The reaction mixture was then quenched with satd NH4Cl
(5 mL), extracted with CH2Cl2 (3 · 10 mL) and the
organic phase dried over MgSO4. After removal of the
solvent at reduced pressure, the crude nitro derivative
obtained was purified by column chromatography
(CHCl3/MeOH 98:2). Selected data of compounds—3d:
mp 89–90 ꢁC (ethyl acetate–hexane). IR (cmÀ1, KBr):
3290;1680:1550. 1H NMR (300 MHz, CDCl3) d: 0.99 (t,
3H, J = 7.3 Hz); 1.69–2.15 (m, 2H); 3.78 (s, 3H); 4.66–
4.84 (m, 1H); 5.41–5.60 (m, 1H); 6.54 (d, 1H, J = 9.5 Hz);
6.91 (d, 2H, J = 8.8 Hz); 7.24 (d, 2H, J = 8.8 Hz); 8.25 (s,
1H). 13C NMR (75 MHz, CDCl3) d: 10.5, 23.9, 55.5, 58.5,
92.7, 114.8, 127.5, 128.7, 160.7, 164.1. Compound 3l: Oil.
IR (cmÀ1, neat): 3310, 1688, 1555. 1H NMR (300 MHz,
CDCl3) d: 1.10–1.45 (m, 2H); 1.55–1.95 (m, 4H); 2.18–
2.24 (m, 2H); 2.40–2.55 (m, 1H); 2.60–2.80 (m, 1H); 5.40
(d, 1H, J = 10.2 Hz); 6.43 (d, 1H, J = 10.2 Hz), 7.15–7.45
(m, 5H); 8.20 (s, 1H). 13C NMR (75 MHz, CDCl3) d:
22.1, 24.3, 31.0, 57.0, 99.5, 127.6, 128.2, 131.5, 160.7,
162.9.
Acknowledgements
Financial support from University of Camerino (Na-
`
`
tional Project ‘Sintesi e Reattivita-attivita di Sistemi
Insaturi Funzionalizzati’) is gratefully acknowledged.
References and notes
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