min, the complexed substrate 2a,b/4a,b (1.2 mmol) was added
as a solid followed by diethyl ether (15 ml). After 10 min, the
reaction was allowed to warm to room temperature and stirred
for 2–3.5 h. After completion, the reaction was worked up by
evaporating the solvent, washing with water and extracting with
dichloromethane. Crystallization from dichloromethane–light
petroleum yielded yellow microcrystals.
Tricarbonyl{(3R*,4R*)-3-methoxycarbonyl-2-oxo-4-phenyl-
3,4,4a,5,6,10b-hexahydro-2H-benzo[h]chromene}chromium(0)
5a. Yellow solid (mp 170–172 ЊC) (Found: C, 61.80; H, 4.35;
C25H20O7Cr requires C, 61.99; H, 4.16%); νmax/cmϪ1 1970, 1900,
1770 and 1740; δH(200 MHz; CDCl3) 2.05–2.20 (m, 1H), 2.30
(s, 3H), 2.35–2.70 (m, 2H), 2.70–2.95 (m, 1H), 3.75 (s, 3H), 3.85
(d, 1H, J 6.3), 4.15 (d, 1H, J 6.3), 5.25–5.35 (m, 2H), 5.40–5.50
(m, 1H), 5.85 (d, 1H, J 6), 7.10 (d, 2H, J 9), 7.15 (d, 2H, J 9);
δC(50.3 MHz; CDCl3) 20.9, 24.6, 26.2, 45.0, 53.0, 54.0, 86.8,
90.9, 91.2, 92.2, 96.2, 106.5, 115.3, 127.5, 129.9, 133.3, 138.0,
140.7, 162.6, 167.2, 232.7.
27.1, 28.2, 41.4, 45.3, 47.2, 89.5, 90.1, 91.6, 94.2, 97.7, 112.3,
120.0, 127.6, 129.9, 137.3, 138.8, 154.9, 198.2, 232.2.
Complex 8a. Red solid (mp 212 ЊC, decomp.) (Found: C,
67.81; H, 4.77; C24H20O4Cr requires C, 67.92; H, 4.75%); νmax
/
cmϪ1 1990, 1920 (br), 1680 and 1620; δH(200 MHz; CDCl3)
1.50–1.65 (m, 1H), 1.85–2.00 (m, 2H), 2.40 (s, 3H), 2.65–2.95
(m, 5H), 5.25 (m, 2H, J 6), 5.60 (t, 1H, J 6), 5.92 (d, 1H, J 7), 6.50
(s, 1H), 7.20 (m, 4H); δC(50.3 MHz; CDCl3) 21.2, 26.0, 29.3,
42.6, 45.4, 47.2, 89.5, 90.5, 92.1, 93.4, 95.5, 111.4, 121.9, 127.5,
129.7, 137.1, 138.7, 155.2, 197.8, 231.9.
Complex 7b. Red solid (mp 184 ЊC) (Found: C, 67.04; H, 3.90;
C23H18O4Cr requires C, 67.31; H, 4.42%); νmax/cmϪ1 1990, 1920
(br), 1680 and 1620; δH(200 MHz; CDCl3) 1.72–1.80 (m, 1H),
2.37 (s, 3H), 2.85–3.05 (m, 4H), 3.05 (m, 1H), 5.20 (d, 1H, J 7),
5.40 (t, 1H, J 6), 5.55 (t, 1H, J 6), 5.80 (d, 1H, J 7), 6.55 (s, 1H),
7.25–7.55 (m, 5H); δC(50.3 MHz; CDCl3) 21.2, 27.1, 28.2, 41.4,
45.3, 47.2, 89.5, 90.1, 91.7, 94.2, 97.7, 112.3, 120.0, 127.6, 129.8,
137.3, 138.8, 154.9, 198.3, 232.2.
Complex 5b. Yellow solid (mp 188–189 ЊC) (Found: C, 61.07;
H, 3.76; C24H18O7Cr requires C, 61.28; H, 3.86%); νmax/cmϪ1
1970, 1900, 1770 and 1740; δH(200 MHz; CDCl3) 2.05–2.30 (m,
1H), 2.35–2.70 (m, 2H), 2.75–3.00 (m, 1H), 3.85 (s, 3H), 3.90 (d,
1H, J 5), 4.20 (d, 1H, J 5), 5.30–5.60 (m, 3H), 5.90 (d, 1H, J 6),
7.20–7.50 (m, 5H); δC(50.3 MHz; CDCl3) 24.7, 26.2, 45.5, 53.0,
53.9, 86.7, 90.9, 91.1, 92.2, 96.1, 106.5, 115.1, 127.7, 128.2,
129.3, 136.5, 140.9, 162.5, 167.2, 232.6.
Complex 8b. Red solid (mp 230 ЊC, decomp.) (Found: C,
66.90; H, 4.01; C23H18O4Cr requires C, 67.31; H, 4.42%); νmax
/
cmϪ1 1990, 1920 (br), 1680 and 1620; δH(200 MHz; CDCl3)
1.25–1.50 (m, 2H), 1.90 (m, 1H), 2.50–3.00 (m, 5H), 5.25 (m, 2H,
J 7), 5.60 (t, 1H, J 6), 5.90 (d, 1H, J 7), 6.50 (s, 1H), 7.25–7.45
(m, 5H); δC(50.3 MHz; CDCl3) 27.4, 28.5, 41.6, 45.5, 46.8, 89.7,
90.5, 91.9, 94.8, 95.3, 112.5, 114.7, 126.4, 128.7, 134.1, 154.9,
159.2, 198.5, 232.9.
Tricarbonyl(3-methoxycarbonyl-2-oxo-4-phenyl-2,3,4,4a,
5,6,7,11b-octahydro[6,7]cyclohepta[b]pyran)chromium(0)
Complex 7c. Red solid (mp 166–167 ЊC) (Found: C, 65.23; H,
4.92; C24H20O5Cr requires C, 65.45; H, 4.58%); νmax/cmϪ1 1990,
1920 (br), 1680 and 1620; δH(200 MHz; CDCl3) 1.55–1.35 (m,
1H), 1.75–1.85 (m, 1H), 2.50–2.85 (m, 4H), 3.05 (m, 1H), 3.85
(s, 3H), 5.20 (d, 1H, J 7), 5.40 (t, 1H, J 6), 5.55 (t, 1H, J 6), 5.85
(d, 1H, J 7), 6.55 (s, 1H), 6.95 (d, 2H), 7.20 (d, 2H); δC(50.3
MHz; CDCl3) 26.1, 29.3, 42.9, 45.6, 46.9, 55.4, 89.4, 90.5, 92.0,
93.8, 95.5, 111.3, 114.5, 122.0, 128.6, 133.8, 155.1, 159.0, 197.8,
231.9.
Complex 8c. Red solid (mp 199 ЊC) (Found: C, 65.03; H, 4.29;
C24H20O5Cr requires C, 65.45; H, 4.58%); νmax/cmϪ1 1990, 1920
(br), 1680 and 1620; δH(200 MHz; CDCl3) 1.25–1.50 (m, 1H),
1.85–2.00 (m, 2H), 2.55–3.00 (m, 5H), 3.85 (s, 3H), 5.25 (m, 1H),
5.65 (t, 1H, J 6), 5.90 (d, 1H, J 7), 6.50 (s, 1H), 6.95 (d, 2H, J 9),
7.20 (d, 2H, J 9); δC(50.3 MHz; CDCl3) 27.1, 28.2, 41.7, 45.4,
46.8, 55.5, 89.4, 90.0, 91.6, 94.2, 94.7, 112.4, 114.6, 126.0, 128.7,
133.8, 154.9, 159.1, 198.3, 232.8.
6a.
Yellow solid (Found: C, 62.70; H, 4.76; C26H22O7Cr requires C,
62.65; H, 4.45%); νmax/cmϪ1 1970, 1900, 1770 and 1740; δH(200
MHz; CDCl3) 2.00–2.20 (m, 2H), 2.30–2.70 (m, 6H), 2.85 (m,
1H), 3.90 (s, 3H), 4.00 (d, 1H, J 5), 4.25 (d, 1H, J 5), 4.30 (s,
1H), 5.40 (m, 2H), 5.60 (t, 1H, J 7), 5.95 (d, 1H, J 6), 6.05 (d,
1H, J 6), 7.30 (br s, 4H); δC(50.3 MHz; CDCl3) 21.2, 29.2, 29.5,
30.8, 31.0, 33.1, 33.3, 46.9, 47.5, 53.3, 53.8, 54.1, 54.3, 88.9,
89.4, 92.1, 92.3, 92.5, 93.2, 93.7, 100.6, 112.5, 112.7, 120.4,
120.4, 120.8, 127.4, 127.6, 130.3, 134.4, 138.4, 141.8, 162.9,
167.6, 232.4, 232.7.
Complex 6b. Yellow solid (Found: C, 61.83; H, 4.38; C25-
H20O7Cr requires C, 61.99; H, 4.16%); νmax/cmϪ1 1970, 1900,
1770 and 1740; δH(200 MHz; CDCl3) 1.80–2.00 (m, 2H), 2.15–
2.30 (m, 2H), 2.40–2.50 (m, 1H), 2.60–2.75 (m, 1H), 3.75 (s,
6H), 3.85 (d, 1H, J 5), 4.10 (d, 1H, J 5), 4.25 (s, 1H), 5.25 (m,
2H), 5.40 (t, 1H, J 7), 5.80 (d, 1H, J 6), 5.90 (d, 1H), 6.90–7.45
(m, 5H); δC(50.3 MHz; CDCl3) 29.7, 30.2, 31.2, 31.5, 33.4, 33.6,
47.1, 47.5, 53.4, 54.0, 54.3, 54.6, 88.9, 89.4, 92.3, 92.6, 92.7,
93.4, 93.8, 100.7, 112.8, 113.0, 120.6, 120.7, 121.2, 127.5, 127.7,
130.4, 134.5, 138.6, 141.9, 162.9, 167.8, 232.7, 233.1.
General method for annulation of complexes 4a,b using ethyl
acetoacetate
Ethyl acetoacetate (260 mg, 2 mmol) was added to ButOK
(10 mmol of K in 1 ml of tert-butyl alcohol) at 0 ЊC. After 10
min, the complexed substrate 4a,b (1 mmol) was added as a
solid followed by THF (5 ml). The reaction was monitored by
TLC, and was found to be complete in 8–12 h. After completion
of the reaction, the solvent was removed under reduced pres-
sure, the reaction mixture washed with water and extracted
using dichloromethane (3 × 20 ml). The diastereomers were
separated using chromatography (gradient elution, 10% ethyl
acetate–90% light petroleum to 40% ethyl acetate–60% light
petroleum). The less polar fraction provided the yellow coloured
major isomer while the red coloured minor isomer was con-
tained in the polar fraction.
General method for annulation of complexes 2a–c using ethyl
acetoacetate
Ethyl acetoacetate (260 mg, 2 mmol) was added to ButOK (10
mmol of K in 1 ml of tert-butyl alcohol) at 0 ЊC. After 10 min,
the complexed substrate 2a–c (1 mmol) was added as solid fol-
lowed by THF (5 ml). The reaction was monitored by TLC, and
was found to reach completion in 8–12 h. After completion,
solvent was removed under reduced pressure, the reaction mix-
ture washed with water and extracted using dichloromethane
(3 × 20 ml). The diastereomers were separated using chrom-
atography (gradient elution, 10% ethyl acetate–90% light
petroleum to 40% ethyl acetate–60% light petroleum). The less
polar fraction provided the minor isomer while the major
isomer was contained in the polar fraction.
Tricarbonyl(2-oxo-4-phenyl-3,4,4a,5,6,7-hexahydro-2H-
dibenzo[a,c]cycloheptene)chromium(0) 9a. Yellow solid (mp
154 ЊC) (Found: C, 68.00; H, 4.79; C25H22O4Cr requires C,
68.49; H, 5.06%); νmax/cmϪ1 1990, 1920, 1680, 1620; δH(200
MHz; CDCl3) 1.65–2.05 (m, 4H), 2.33 (s, 3H), 2.40–2.64 (m,
1H), 2.64–3.05 (m, 4H), 3.35 (q, 1H, J 10), 5.14 (m, 2H), 5.35
(d, 1H, J 6), 5.43 (t, 1H, J 7), 6.30 (s, 1H), 7.10 (m, 4H); δC(50.3
MHz; CDCl3) 21.1, 24.7, 31.3, 33.0, 42.0, 45.4, 45.6, 87.6, 90.9,
94.5, 96.2, 110.7, 111.3, 127.2, 129.6, 130.2, 136.8, 139.7, 161.0,
168.0, 198.0, 232.5.
Tricarbonyl[3-oxo-1-(p-tolyl)-1,2,3,9,10,10a-hexahydrophen-
anthrene]chromium(0) 7a. Red solid (mp 166 ЊC) (Found: C,
67.67; H, 4.42; C24H20O4Cr requires C, 67.92; H, 4.75%);
νmax/cmϪ1 1990, 1920 (br), 1680 and 1620; δH(200 MHz; CDCl3)
1.72–1.80 (m, 1H), 2.37 (s, 3H), 2.85–3.05 (m, 4H), 3.05 (m, 1H),
5.20 (d, 1H, J 7), 5.40 (t, 1H, J 6), 5.55 (t, 1H, J 6), 5.80 (d, 1H,
J 7), 6.55 (s, 1H), 7.20 (m, 4H); δC(50.3 MHz; CDCl3) 21.2,
Complex 10a. Red solid (mp 194 ЊC) (Found: C, 67.99; H,
J. Chem. Soc., Perkin Trans. 1, 1998
981