A. Garc ꢀı a-Torres et al. / Tetrahedron Letters 45 (2004) 2085–2088
2087
L. Velasco, H. Rios, N. Zavala, E. Hernandez and A.
Pe n~ a, for technical support.
O
DLP
Cl(CH ) Cl
reflux
1
a
+
O
I
2
2
O
MeO
O
1
4 (75%)
1
3
References and notes
Me
O
O
NC
NO2
I
NC
1
. For review of homolytic substitution see: (a) Bertrand, F.;
Le Guyader, F.; Liguori, L.; Ouvry, G.; Quiclet-Sire, B.;
Zard, S. Z. Comptes Rendus de lÕAcademie des Sciences
Series IIC Chemistry 2001, 4, 547; (b) Studer, A. In Radicals
in Organic Synthesis; Renaud, P., Sibi, M., Eds.; Wiley
VCH: Weinhem, 2001; 2, pp 62–76; see also: (c) Tate, E.;
Zard, S. Z. Chem. Commun. 2002, 1430, and references
cited therein.
N
DLP
Cl(CH ) Cl
reflux
N
+
Me
O
2
2
O
15
16
17 (35%)
Scheme 5.
2
. (a) Corey, E. J.; Estreicher, H. J. Am. Chem. Soc. 1978, 100,
294; (b) Seebach, D.; Colvin, E. W.; Weller, T. Chimia
979, 33, 1; (c) Barret, A. G. M.; Graboski, G. G. Chem.
6
1
R
O
Rev. 1986, 86, 751; (d) Rosini, G.; Ballini, R. Synthesis
1988, 833; (e) Several articles in Tetrahedron Symposia-in-
print 41, Nitroalkanes and nitroalkenes in synthesis, Tet-
rahedron 1990, 46, 7313–7598; (f) Barret, A. G. M.;
Graboski, G. G. Chem. Rev. 1991, 20, 95.
O
NO2
+
DLP
R (CH ) Cl
2
2
2
MeO
X
∆
MeO
2
1
1
b
18 R = 4-Cl( CH ) 19 R = Me
3. (a) Kohler, E. P.; Stone, J. R. J. Am. Chem. Soc. 1930, 52,
61; (b) Buckley, G. D. J. Chem. Soc. 1947, 1494; (c)
6
4
7
X = I
X = I
Buckley, G. D.; Ellery, E. J. J. Chem. Soc. 1947, 1497; (d)
Ashwood, M. S.; Bell, L. A.; Houghton, P. G.; Wright,
S. H. B. Synthesis 1988, 379; (e) Yao, C.-F.; Chen, W.-W.;
Lin, Y.-M. Tetrahedron Lett. 1996, 37, 6399; (f) Yao,
C.-F.; Kao, K.-H.; Liu, Y.-M.; Lin, W.-W.; Jang, J.-J.; Liu,
J.-Y.; Chuang, M.-C.; Shiue, J.-L. Tetrahedron 1988, 54,
2
0 R = 4-Cl( CH )
X = S( C)OEt
6
4
Scheme 6. Free radical addition/elimination process of a-iodoacetone
with b-nitrostyrene.
7
91; (g) Liu, J.-T.; Lin, W.-W.; Jang, J.-J.; Liu, J.-Y.; Yan,
ducing the expected olefin 17 in low yield as an insepa-
rable 3:1 mixture of the E and Z isomers. This result
may well be explicable as another example of a polarity-
mismatched situation.
M.-C.; Hung, C.; Kao, K.-H.; Wang, Y.; Yao, C.-F.
Tetrahedron 1999, 55, 7115.
. (a) Han, Y.; Hung, Y.-Z.; Zhou, C.-M. Tetrahedron Lett.
4
1
996, 37, 3347; (b) Yao, C.-F.; Chu, C.-M.; Liu, J.-T.
J. Org. Chem. 1998, 63, 719; (c) Chu, C.-M.; Liu, J.-T.; Lin,
W.-W.; Yao, C.-F. J. Chem. Soc., Perkin Trans. 1 1999, 47;
So far, attempts to extend the process to the a-keto
radicals derived from the iodides 18 and 19 or the
xanthate 20 and the b-nitrostyrene 1b, have failed.
The thermally sensitive iodides decompose under the
reaction conditions while the xanthate produces
complex mixtures not containing the expected enone 21
(
9
d) Yao, C.-F.; Chu, C.-M.; Liu, J.-T. Chem. J. Eur. 2003,
, 2123; See also: (e) Sebach, D.; Schafer, H.; Schmidt, B.;
Schreiber, M. Angew. Chem., Int. Ed. Engl. 1992, 31, 1587;
(f) Hu, Y.; Yu, J.; Yang, S.; Wang, J.-X.; Yin, Y. Synlett
1998, 1213; (g) Hu, Y.; Yu, J.; Yang, S.; Wang, J.-X.; Yin,
Y. Synth. Commun. 1999, 29, 1157; (h) Namboothiri, I. N.
N.; Hassner, A. J. Organomet. Chem. 1996, 518, 69.
. For a similar elimination of the nitro group see: Ouvry, G.;
Quiclet-Sire, B.; Zard, S. Z. Org. Lett. 2003, 5, 2907.
. Zard, S. Z. In Radicals in Organic Synthesis; Renaud, P.,
Sibi, M., Eds.; Wiley VCH: Weinhem, 2001; pp 90–108;
Zard, S. Z. Angew. Chem., Int. Ed. 1997, 36, 672.
. Ollivier, C.; Bark, T.; Renaud, P. Synthesis 2000, 1598.
. Typical experimental procedure: To a deaerated solution of
the iodide (1 mmol) and nitrostyrene (2 mmol) in refluxing
1,2-dichloroethane (2 mL/mmol), dilauroyl peroxide
(1.8 mmol) was added portionwise over a 15 h period. The
reaction was monitored by TLC. The solvent was removed
under reduced pressure and the crude residue purified by
chromatography on a silica gel column (ethyl acetate/
(
Scheme 6).
5
In closing, we have demonstrated that the substitution
of b-nitrostyrenes by appropriate electrophilic carbon-
centered radicals, mediated by DLP, can be effected in
preparatively useful yields. The process has the distinct
6
7
8
advantage of using near stoichiometric quantities of the
4
reagents, in contrast to the related Et
3
B method. The
results also once again demonstrate the synthetic
potential of nitrostyrenes in radical vinylation reactions,
and the products have considerable synthetic potential
for the synthesis of even more complex molecular enti-
ties. Work along these lines is underway.
hexane) to furnish the desired product. Selected spectro-
1
scopic data: 11a H NMR (200 MHz, CDCl
3
) d: 3.31 (dd,
J ¼ 1:0, 6.3 Hz, 2H), 3.53–3.7 (m, 8H), 6.31 (dt, J ¼ 6:0,
1
5.8 Hz, 1H), 6.49 (d, J ¼ 16:0 Hz, 1H), 7.22–7.39 (m, 5H).
3
1
3
C NMR (75 MHz, CDCl
) d: 169.7, 136.8, 133.0, 128.5,
Acknowledgements
ꢁ1
1
27.6, 126.2, 122.6, 66.8, 66.6, 46.3, 42.0, 37.7. IR (cm ) m:
2
966, 2920, 1632,1436, 1113. MS (EI) m=z ¼ 114 (100%;
We thank CONACYT (37312-E) for generous financial
support and Dr. Joseph M. Muchowski for many
friendly discussions. Also we thank R. Pati n~ o, J. P ꢀe rez,
þ
þ
1
3
M ), 231 (56% M ). 11b H NMR (300 MHz, CDCl ) d:
3.28 (dd, J ¼ 1:4, 6.7 Hz, 2H), 3.49–3.70 (m, 8H), 3.80 (s,
3H), 6.16 (dt, J ¼ 6:7, 16.1 Hz, 1H), 6.42 (d, J ¼ 15:8 Hz,