LETTER
Iodine-Catalysed Bohlmann–Rahtz Cyclodehydration Reactions
651
Table 3 Catalytic Cyclodehydration of 3a–h
(9) Bagley, M. C.; Hughes, D. D.; Lloyd, R.; Powers, V. E. C.
Tetrahedron Lett. 2001, 42, 6585.
(10) Hughes, D. D.; Bagley, M. C. Synlett 2002, 1332.
11) (a) Bagley, M. C.; Dale, J. W.; Ohnesorge, M.; Xiong, X.;
Bower, J. J. Comb. Chem. 2003, 5, 41. (b) Bashford, K. E.;
Burton, M. B.; Cameron, S.; Cooper, A. L.; Hogg, R. D.;
Kane, P. D.; MacManus, D. A.; Matrunola, C. A.; Moody, C.
J.; Robertson, A. A. B.; Warne, M. R. Tetrahedron Lett.
Entry
3
a
b
c
d
e
f
R
R¢
4
a
b
c
d
e
f
Yield (%)a
>98
>98
>98
92b
(
1
2
3
4
5
6
7
Et
Me
Me
Ph
t-Bu
Et
2
003, 44, 1627.
(12) (a) Bagley, M. C.; Xiong, X. Org. Lett. 2004, 6, 3401.
b) Adamo, M. F. A.; Adlington, R. M.; Baldwin, J. E.;
Pritchard, G. J.; Rathmell, R. E. Tetrahedron 2003, 59,
197. (c) Adlington, R. M.; Baldwin, J. E.; Catterick, D.;
Pritchard, G. J.; Tang, L. T. J. Chem. Soc., Perkin Trans. 1
000, 2311. (d) Baldwin, J. E.; Catterick, D.; Pritchard, G.
Et
4-MeOC H
6
4
4
(
Et
4-ClC H
>98
97
6
4
2
t-Bu
t-Bu
t-Bu
Ph
2
g
h
4-MeOC H
g
h
>98
92
6
J.; Tang, L. T. J. Chem. Soc., Perkin Trans. 1 2000, 303.
(e) Moody, C. J.; Bagley, M. C. Synlett 1998, 361.
8
4-ClC H
6
4
(
13) (a) Moody, C. J.; Bagley, M. C. Synlett 1998, 361.
a
Isolated yield of pure 4 after an aqueous work up.
Not isolated yield of pyridine 4d but from analysis of H NMR
(
b) Bagley, M. C.; Bashford, K. E.; Hesketh, C. L.; Moody,
b
1
C. J. J. Am. Chem. Soc. 2000, 122, 3301. (c) Moody, C. J.;
Bagley, M. C. Chem. Commun. 1998, 2049.
14) Bagley, M. C.; Dale, J. W.; Jenkins, R. L.; Bower, J. Chem.
Commun. 2004, 102.
15) (a) Bagley, M. C.; Dale, J. W.; Xiong, X.; Bower, J. Org.
Lett. 2003, 5, 4421. (b) Bagley, M. C.; Chapaneri, K.; Dale,
J. W.; Xiong, X.; Bower, J. J. Org. Chem. 2005, 70, in
review.
spectrum which showed that dienone 3d (8%) was also present.
(
(
References
(
(
(
1) Bohlmann, F.; Rahtz, D. Chem. Ber. 1957, 90, 2265.
2) Bagley, M. C.; Dale, J. W.; Bower, J. Synlett 2001, 1149.
3) Bagley, M. C.; Lunn, R.; Xiong, X. Tetrahedron Lett. 2002,
(16) Bagley, M. C.; Glover, C.; Merritt, E. A.; Xiong, X. Synlett
2004, 811.
4
3, 8331.
(17) General Procedure for the Catalytic Cyclodehydration
of Aminodienones 3 Using I2.
(
(
(
(
(
4) Bagley, M. C.; Dale, J. W.; Hughes, D. D.; Ohnesorge, M.;
Phillips, N. G.; Bower, J. Synlett 2001, 1523.
5) Bagley, M. C.; Chapaneri, K.; Xiong, X. Tetrahedron Lett.
A solution of aminodienone 3 (0.2 mmol, 1 equiv) and
iodine (0.04 mmol, 20 mol%) in EtOH (4 mL) was stirred at
r.t. for 30 min and an aq solution of Na S O (10% w/v, 10
2
004, 45, 6121.
6) Bagley, M. C.; Dale, J. W.; Bower, J. Chem. Commun. 2002,
682.
2
2
3
mL) was added. The mixture was extracted with CH Cl
2
2
1
(3 × 20 mL) and the organic extracts were combined, dried
7) Bagley, M. C.; Hughes, D. D.; Sabo, H. M.; Taylor, P. H.;
Xiong, X. Synlett 2003, 1443.
8) Bagley, M. C.; Brace, C.; Dale, J. W.; Ohnesorge, M.;
Phillips, N. G.; Xiong, X.; Bower, J. J. Chem. Soc., Perkin
Trans. 1 2002, 1663.
(Na SO ) and evaporated in vacuo to give pyridine 4.
2
4
(18) Pyridines 4a–h exhibited physical and spectroscopic
properties that were in agreement with literature data (see
refs. 1, 8, 11a, and 15b for detailed information).
Synlett 2005, No. 4, 649–651 © Thieme Stuttgart · New York