J. CHEM. RESEARCH (S), 1999 339
Experimental
Received, 18th January 1999; Accepted, 12th February 1999
Paper E/9/00444K
Allylation of Cyclohexanone 1 with 2,3-Dibromopropene.öTo a sol-
ution of the enolate of cyclohexanone, prepared from lithium
3
diisopropylamide and cyclohexanone (1.0 g, 10 mmol) in THF (4 cm )
cooled to � 75 8C, was added a solution of 2,3-dibromopropene
3
(
2.0 g, 10 mmol) in THF (4 cm ). The solution was warmed gradually
to room temperature. Column chromatography on silica gel
(
hexane^ethyl acetate, 50:1) gave ketone 2 (1.4 g, 64% yield), an oil,
H NMR (CDCl3) d 5. 61 (1H, d, J 1:5 Hz, CH), 5.44 (1H,
1
References
t, J 0:7 Hz, CH), 2.99 (1H, dd, J 14:5, 4.7 Hz, CHC), 2.68
(
(
1H, m, CHC ) and 2.46^1.22 (9 H, m). HRMS: Found m/z 137.0929
1
For reviews see: T.-L. Ho. Tandem Organic Reactions, Wiley,
New York, 1992; R. A. Bunce, Tetrahedron, 1995, 51, 13103;
L. F. Tietze, Chem. Rev., 1996, 96, 115; P. J. Parsons, C.
S. Penkett and A. J. Shell, Chem. Rev., 1996, 96, 195; M.
Malacria, Chem. Rev., 1996, 96, 289; S. Handa and G.
Pattenden, Contemp. Org. Synth., 1997, 4 196.
M
� Br). Calc. for C9H13O: (M � Br), 137.0966.
Wittig Reaction of 2.öTo a suspension of Ph3PCH2OMeCl (4.6 g,
3
1
3.5 mmol) in dry diethyl ether (27 cm ) cooled to � 858C was added
n
� 3
3
a solution of Bu Li (1.6 mol dm ; 8.4 cm , 13.5 mmol). A solution
3
of ketone 2 (1.46 g, 6.7 mmol) in dry diethyl ether (9 cm ) was then
added and the mixture was warmed gradually to room temperature.
Column chromatography gave 3E and 3Z in 83% yield and in a ratio
of 14:1. 3E: 1H NMR (CDCl3) d 5.78 (1 H, s, CHOMe), 5.52 (1H, d,
J 1:2 Hz, CH), 5.42 (1H, d, J 1.5 Hz, CH), 3.54 (3 H, s,
2
3
4
A. Fukuzawa, A. Furusaki, M. Ikura and T. Masamune, J.
Chem. Soc., Chem. Commun., 1985, 222; J. W. van Klink,
A. J. Barlow, N. B. Perry and R. T. Weavers, Tetrahedron
Lett., 1999, 40, 1409.
OMe), 2.65^1.95 (5 H, m, CH2 and CH) and 1.7^1.3 (6 H, m, CH2).
The bromoacetalization of the mixture of 3E and 3Z (1.3:1)
1
� 3
3
Z
H NMR (CDCl3) d 5.79 (1H, s, CHOMe), 5.56 (1H, d,
obtained by the Wittig reaction of 2 (0.05 mol dm ) gave
J 1.5 Hz, CH), 5.41 (1H, d, J 1.5 Hz, CH), 3.51 (3 H, s,
4a in a similar yield: B. E. Maryano¡ and A. B. Reita,
Phosphorus Sulfur, 1986, 27, 167.
OMe), 3.22 (1H, m, CH), 2.57 (2 H, m, CH2) and 2.0^1.2 (8 H,
m, CH2). HRMS (3E 3Z): Found m/z 212.0198 (M � MeOH).
Crystal Data for 4a: C14H20Br2O2, Mr 380:1, monoclinic,
Calc. for C10H13Br: (M � MeOH, 212.0201.
space group P21, a 10:519ꢁ5, b 12:038ꢁ6, c 6:463ꢁ3
3
Bromoacetalization of 3.öTo a solution of 3 (E : Z 14:1) (100 mg,
Ð, b 98:51ꢁ48, V 809:4ꢁ7 Ð , Z 2, Cu-Ka radiation,
3
� 1
0
.4 mmol) in dry CH2Cl2 (1.5 cm ) cooled to � 788C was added a sol-
l 1:54184 Ð, T 293 K, m 63:01 cm
, 1338 re£ections
3
ution of propargyl alcohol (0.5 cm ) and NBS (73 mg, 0.4 mmol) in
measured, 1216 unique re£ections, 679 observed re£ections
I > 2sꢁI, R 0:089. Full crystallographic details, excluding
structure factors, have been deposited at the Cambridge
Crystallographic Data Centre (CCDC). See Instructions for
Authors, J. Chem. Research (S), 1998, Issue 1. Any request
to the CCDC for this material should quote the full literature
citation and the reference number 423/20.
3
CH2Cl2 (0.5 cm ). Column chromatography on silica gel [22 g;
hexane^ethyl acetate (50:1)] gave 4a (86 mg, 55% yield). Compound
1
4
a, mp 45^468C (from hexane); H NMR (CDCl3) d 5.59 (1H, t,
J 1:5 Hz, CH), 5.45 (1H, s, CH), 4.65 [1H, s, HC(OMe)O], 4.42
(
2 H, d, J 2:5 Hz, CH2O), 3.66 (3 H, s, OMe), 2.93 (1H, d,
J 12:0 Hz, CHC 2.6^2.4 (2 H, m, CHC and CH), 2.50 (1H, t,
J 2:5 Hz, CꢀCH and 2.2^1.4 (8 H, m, CH2). HRMS: Found m/z
5
6
A. L. J. Beckwith and D. M. O'Shea, Tetrahedron Lett., 1986,
27, 4525.
2
99.0627 (M � Br). Calc. for C14H20BrO2 : ꢁM � Br), 299.0647.
Radical Cyclization of 4a.öA solution of 4a (30 mg, 0.08 mmol),
Y. Ueno, K. Chino, M. Watanabe, O. Moriya and M.
Okawara, J. Am. Chem. Soc., 1982, 104, 5564; Y. Ueno,
O. Moriya, K. Chino, M. Watanabe and M. Okawara, J.
Chem. Soc., Perkin Trans. 1, 1986, 1351; G. Stork, R. Mook
Jr., S. A. Biller and S. D. Rychnovsky, J. Am. Chem. Soc.,
1983, 105, 3741.
G. Stork and N. H. Baine, J. Am. Chem. Soc., 1982, 104, 2321;
N. N. Marinovic and H. Ramanathan, Tetrahedron Lett.,
1983, 24, 1871.
H. Nagano, M. Tori, M. Shiota and J. de Pascual Teresa, Bull.
Chem. Soc. Jpn., 1984, 57, 2971.
A. Srikrishna, S. Nagaraju and G. V. R. Sharma, J. Chem.
Soc., Chem. Commun., 1993, 285.
n
Bu 3SnH (93 mg, 0.32 mol) and a catalytic amount of AIBN in
3
dry diethyl ether (4 cm ) was irradiated with 400 W Xe lamp at room
temperature for 4.5 h under nitrogen. After treatment of the mixture
with potassium £uoride^water, the reaction mixture was
chromatographed on silica gel [11g; hexane^ethyl acetate (100:1)]
1
to give 6 (17 mg, 94%), H NMR (CDCl3) d 4.93 (1H, d, J 2:7Hz,
7
CH), 4.84 (1H, d, J 2:7 Hz, CH), 4.79 [1H, s, HC(OMe)O],
3
.68 (2 H, s, OCH2), 3.36 (3 H, s, OMe), 2.18 (1H, dd, J 14.0,
.4 Hz, CH), 2.10 (1H, tt, J 14:0, 2.7 Hz, CH), 2.0^1.0 (9 H,
6
8
9
1
3
m, CH2 and CH), and 0.98 (3 H, s, Me); C NMR (CDCl3) d 161.1,
1
07.7, 104.4, 78.8, 57.4, 55.2, 54.5, 46.7, 38.0, 29.4, 27.5, 26.2, 23.7
and 16.6. HRMS: Found m/z 222.1623 (M ). Calc. for C14H22O2 :
M, 222.1607.
10 No attempt was made to determine the stereochemistry of the
inseparable dibromoacetals and cyclization products.
11 The tandem radical cyclization of the homologous dibro-
moacetals derived from cycloheptanone gave three
5-exo-dig-5-exo-trig and two 5-exo-dig-6-(formal)-endo-trig
cyclization products in moderate yield. The reaction of the
1
Compound 5.ö H NMR (CDCl3) d 5.52 (1H, t, J 1:5 Hz,
CH), 5.40 (1H, t, J 2:0 Hz, CH), 5.00 (1H, t, J 2.0 Hz,
CH), 4.94 (1H, t, J 2:0 Hz, CH), 4.84 [1H, s, HC(OMe)O],
.43 [1H, dt, J 13:5, 2.0 Hz, CHO), 4.33 (1 H, dt, J 13:5, 2.0 Hz,
CHO), 3.37 (3 H, s, OMe), 2.36 (1H, d, J 14:2 Hz, CHC), 2.11
4
n
(
1H, dd, J 14:2, 11.2 Hz, CHC) and 2.05^0.85 (9 H, m, CH2
dibromoacetals derived from cyclopentanone with Bu 3SnH
and CH). HRMS: Found m/z 300.0684 (M ). Calc. for
gave two 5-exo-dig-5-exo-trig and
endo-trig cyclization products.
a 5-exo-dig-6-(formal)-
C14H21BrO2: M, 300.0725.