G. Srini6as, M. Periasamy / Tetrahedron Letters 43 (2002) 2785–2788
2787
TiCl4
.
.
R1
..
R1
R1
R
R
R
+
R1
-
R
N
N
N
:
N
Cl
TiCl4
TiCl4
TiCl3
H
(A)
(B)
HTiCl3
.
.
R1
..
R1
R
R
1
R + R
N
N
..
N
-
Cl
Et3N
2TiCl4/Et3N
H
or
H
O2/workup
+
Et3NH Cl-
H
(C)
(D)
Et3N
TiCl4
HTiCl3
TiCl2
2TiCl3
+
Et3NH Cl-
Scheme 1.
References
13. Ballini, R.; Bosica, G.; Marcantoni, E.; Vita, P. J. Org.
Chem. 2000, 65, 5854.
1
. (a) Reetz, M. T. Organotitanium Reagents in Organic
Synthesis; Springer: Berlin, 1986; (b) Mukaiyama, T.
Angew. Chem., Int. Ed. Engl. 1977, 16, 817.
. (a) Crimmins, M. T.; King, B. W.; Tabet, E. A. J. Am.
Chem. Soc. 1997, 119, 7883; (b) Crimmins, M. T.; Chaud-
hary, K. Org. Lett. 2000, 2, 775; (c) Han, Z.; Uehira, S.;
Tsuritani, T.; Shinokubo, H.; Oshima, K. Tetrahedron
14. (a) Periasamy, M.; Srinivas, G.; Bharathi, P. J. Org.
Chem. 1999, 64, 4204; (b) Periasamy, M.; Bharathi, P.
Org.Lett. 1999, 1, 857; (c) Periasamy, M.; Srinivas, G.;
Karunakar, G. V.; Bharathi, P. Tetrahedron Lett. 1999,
2
40, 7577; (d) Periasamy, M.; Bharathi, P. Organometallics
2000, 19, 5511; (e) Periasamy, M.; Jayakumar, K. N.;
Bharathi, P. J. Org. Chem. 2000, 65, 3548; (f) Periasamy,
M.; Dharma Rao, V. Tetrahedron: Asymmetry 2000, 11,
2
001, 57, 987; (d) Harrison, C. R. Tetrahedron Lett. 1987,
2
8, 4135.
1151; (g) Periasamy, M.; Jayakumar, K. N.; Bharathi, P.
3. Tsuritani, T.; Ito, S.; Shinokubo, H.; Oshima, K. J. Org.
Chem. 2000, 65, 5066.
Chem. Commun. 2001, 1728; (h) Periasamy, M.; Srinivas,
G.; Suresh, S. Tetrahedron Lett. 2001, 42, 7123.
4
. (a) Shi, M.; Feng, Y. S. J. Org. Chem. 2001, 66, 406; (b)
Kataoka, T.; Kinoshita, H.; Kinoshita, S.; Iwamura, T.;
Watanabe, S. Angew.Chem., Int. Ed. Engl. 2000, 39, 2358;
15. Typical experimental procedure: Dichloromethane (20
mL), the enamine (5 mmol) and Et N (17 mmol) were
3
taken under N . TiCl4 (12 mmol 2.64 mL of a 1:1
2
(c) Shi, M.; Jiang, J. K.; Cui, S. C.; Feng, Y. S. J. Chem.
solution of TiCl /CH Cl ) in dichloromethane (10 mL)
4
2
2
Soc., Perkin Trans. 1 2001, 390; (d) Shi, M.; Jiang, J. K.;
Feng, Y. S. Org. Lett. 2000, 2, 2397.
was added dropwise under N at 0°C for 15 min. The
2
reaction mixture was stirred for 0.5 h at 0°C and stirred
further for 7–8 h at 25°C. It was quenched with saturated
5
. (a) Matsumara, Y.; Nishimura, M.; Hiu, H.; Watanabe,
M.; Kise, N. J. Org. Chem. 1996, 61, 2809; (b) Kise, N.;
Kumada, K.; Terao, Y.; Ueda, N. Tetrahedron 1998, 54,
K CO3 solution (15 mL). The organic layer was sepa-
2
rated and the aqueous layer was extracted with
dichloromethane (2×25 mL). The combined organic
extract was washed with brine (10 mL) and dried over
anhydrous K CO . The solvent was removed and the
2
697; (c) Zhou, L.; Zhang, Y. Tetrahedron 2000, 56, 2953
and references cited therein.
6
7
8
. Han, Z.; Shinokubo, H.; Oshima, K. Synlett 2001, 1421.
. Balme, G.; Gore, J. J. Org. Chem. 1983, 48, 3336.
. Chandrashekar, S.; Ramachandar, T.; Venkat Reddy,
M.; Takhi, M. J. Org. Chem. 2000, 65, 4729.
2
3
residue was chromatographed on a silica gel column
using 0.5% EtOAc/hexane mixture as eluent.
13
1
6. Physical constants and spectroscopic data C NMR (50
9
. Ding, Y.; Hu, J. J. Chem. Soc., Perkin Trans. 1 2000,
MHz, CDCl ) for compounds 2a–2g. Compound 2a: mp
1
651.
3
7
13
5
1
0–52°C (lit 51–54°C), C NMR (l ppm) 49.44, 67.00,
1
0. Desai, P.; Schildknegt, K.; Agrios, K. A.; Mossman, C.;
13
15.80, 120.10, 129.25, 151.41. Compound 2b: C NMR
Milligan, G. L.; Aube, J. J. Am. Chem. Soc. 2000, 122,
(
l ppm) 24.90, 52.80, 111.61, 121.43, 124.36, 124.89,
7
226.
13
1
1
1. Langer, P.; Albrecht, U. Synlett 2000, 526.
2. Concellon, J. M.; Bernard, P. L.; Riego, E.; Garcia-
Granda, S.; Forcen-Acebal, A. J. Org. Chem. 2001, 66,
125.60, 126.00, 128.35, 135.15, 147.86. Compound 2c:
C
NMR (l ppm) 24.27, 25.60, 50.93, 116.72, 119.54, 129.10,
13
152.00. Compound 2d: C NMR (l ppm) 14.37, 25.88,
2
764.
50.80, 60.62, 114.00, 115.60, 117.66, 130.98, 131.63,