1170
H.-H. Lin et al. / Tetrahedron Letters 47 (2006) 1167–1171
OTMS
O
1.
I
R1
R1
R2
2. t-BuLi
NaI
m-CPBA
3. CuCN, HMPA
4. TMSCl, Et3N
R2
12a R = H, R = H
13a-c
1
2
12b R = H, R = CH
1
2
3
12c R = CH , R = H
1
3
2
I
O
O
I
O
I
I
R1
R1
R1
AlCl3, ICl
Cl
Cl
+
I
CH2Cl2, 0oC
R2
R2
R2
15a-c
16a-c
14a, 64% (two steps)
14b, 59% (two steps)
14c, 32% (two steps)
15a + 16a, 87% (1 : 1)a
15b + 16b, 86% (1.8 : 1)a
15c + 16c, 81% (2.2 : 1)a
aRatio of the products was determined from the 1H NMR spectra of products.
Scheme 4.
T. Tetrahedron Lett. 1998, 39, 7357; (i) Kitagawa, O.;
Suzuki, T.; Inoue, T.; Watanabe, Y.; Taguchi, T. J. Org.
Chem. 1998, 63, 9470; (j) Kitagawa, O.; Suzuki, T.;
Fujiwara, H.; Taguchi, T. Tetrahedron Lett. 1999, 40,
2549; (k) Kitagawa, O.; Suzuki, T.; Fujiwara, H.; Fujita,
M.; Taguchi, T. Tetrahedron Lett. 1999, 40, 4585; (l)
Kitagawa, O.; Fujiwara, H.; Suzuki, T.; Taguchi, T.; Shiro,
M. J. Org. Chem. 2000, 65, 6819.
allenyl groups was detected (Table 1, entries 1–9). In
the cases of 14a–c, addition of chloride ion to the iodo-
nium moieties became much faster than cyclization and
afforded 15a–c and 16a–c as a mixture of products.
In summary, we have developed a convenient iodocar-
bocyclization reaction of a-iodocycloalkanones bearing
an allenyl side chain. This reaction provides a new
method to prepare spirocyclic ketones 5 and 6 bearing
allylic iodide moieties. Selective formation of either 5
or 6 as the major product is achieved through control-
ling the reaction temperature. Furthermore, this ionic
iodocarbocyclization reaction is complementary to our
photo-cyclization method6 reported earlier. This ionic
cyclization occurred at the central carbon of the allene
group whereas the photo-induced cyclization reacted
at the proximal carbon of the allene group.
2. Toru, T.; Kawai, S.; Ueno, Y. Synlett 1996, 539.
3. (a) Curran, D. P.; Chen, M.-H.; Kim, D. J. Am. Chem. Soc.
1986, 108, 2489; (b) Curran, D. P.; Kim, D. Tetrahedron
Lett. 1986, 27, 5821; (c) Curran, D. P.; Chang, C.-T.
Tetrahedron Lett. 1987, 28, 2477; (d) Curran, D. P.; Chang,
C.-T. J. Org. Chem. 1989, 54, 3140; (e) Curran, D. P.
Synthesis 1988, 417, 489; (f) Jasperse, C. P.; Curran, D. P.;
Fevig, T. L. Chem. Rev. 1991, 91, 1237.
4. (a) Marek, I.; Chakraborty, A. Chem. Commun. 1999, 2375;
(b) Marek, I. J. Chem. Soc., Perkin Trans. 1 1999, 535;
(c) Oshima, K.; Yorimitsu, H.; Nakamura, T.; Shinokubo,
H. J. Org. Chem. 1998, 63, 8604; (d) Curran, D. P.; Chang,
C.-T. Tetrahedron Lett. 1990, 31, 933.
Acknowledgements
5. Sha, C.-K.; Lee, F.-C.; Lin, H.-H. Chem. Commun. 2001,
39.
6. Sha, C.-K.; Lin, H.-H.; Chang, W.-S.; Luo, S.-Y. Org. Lett.
2004, 6, 3289.
7. Sha, C.-K.; Young, J.-J.; Jean, T.-S. J. Org. Chem. 1987, 52,
3919.
We thank the National Science Council for financial
support of this research through the grant NSC93-
2113-M-007-025.
8. A representative procedure for iodocarbocyclization: To a
solution of compound 4a (100 mg, 0.36 mmol) in CH2Cl2
(4.0 mL) was added AlCl3 (70 mg, 0.54 mmol) at À78 ꢁC, or
0 ꢁC, or 30 ꢁC. The mixture was stirred at À78 ꢁC, or 0 ꢁC,
or 30 ꢁC for 15 min. A solution of ICl in CH2Cl2 (1 M,
0.43 mL, 0.43 mmol) was added dropwise at À78 ꢁC, or
0 ꢁC, or 30 ꢁC. The reaction mixture was stirred at À78 ꢁC,
or 0 ꢁC, or 30 ꢁC for 5 min and then quenched with H2O
(20 mL), saturated Na2S2O3 solution (13 mL) and saturated
NaHCO3 solution (13 mL). The mixture was extracted with
EtOAc (15 mL · 3). The combined organic layers were
washed with brine and dried (MgSO4). Concentration and
silica gel column chromatography (EtOAc/hexane = 1:150)
gave products 5a and 6a (80 mg, 83%) as a pale yellow
liquid.
References and notes
1. (a) Kitagawa, O.; Inoue, T.; Taguchi, T. Tetrahedron Lett.
1992, 33, 2167; (b) Kitagawa, O.; Inoue, T.; Hirano, K.;
Taguchi, T. J. Org. Chem. 1993, 58, 3106; (c) Kitagawa, O.;
Inoue, T.; Taguchi, T. Tetrahedron Lett. 1994, 35, 1059; (d)
Inoue, T.; Kitagawa, O.; Kurumizawa, S.; Ochiai, O.;
Taguchi, T. Tetrahedron Lett. 1995, 36, 1479; (e) Inoue, T.;
Kitagawa, O.; Ochiai, O.; Shiro, M.; Taguchi, T. Tetrahe-
dron Lett. 1995, 36, 9333; (f) Inoue, T.; Kitagawa, O.; Oda,
Y.; Taguchi, T. J. Org. Chem. 1996, 61, 8256; (g) Inoue, T.;
Kitagawa, O.; Saito, A.; Taguchi, T. J. Org. Chem. 1997,
62, 7384; (h) Kitagawa, O.; Suzuki, T.; Inoue, T.; Taguchi,