C-Stannylated Troponoids
405
1,4-dioxan (5ꢀ0 ml) and the resulting solution was heated
at reꢃux for 20 h. The cooled reaction mixture was then
poured into water (10 ml) and CH2Cl2 (10 ml) added. The
phases were separated and the aqueous phases extracted with
CH2Cl2 (3ꢂ10 ml). The combined organic phases were then
washed with water (2ꢂ20 ml), dried (MgSO4), ꢁltered and
concentrated under reduced pressure to give a yellow oil which
was subjected to preparative t.l.c. (silica gel, 1 : 1 CH2Cl2/Et2O
elution). The single major and chromophoric band (RF 0ꢀ4)
was extracted (CH2Cl2/Et2O) to give the title compound (23)
(51 mg, 72%) as light-yellow microcrystals, m.p. 140–141ꢁC
[lit. (1991)3 140–141ꢀ5ꢁC] (Found: M+ꢃ, 212ꢀ0837. Calc. for
Hz, 1H, H 7; 6ꢀ93, dd, J 11ꢀ9, 9ꢀ1 Hz, 1H, H 6; 6ꢀ92, m, 1H,
H 3; 3ꢀ93, d, J 0ꢀ6 Hz, 3H, OCH3. 13C n.m.r. (100 MHz) see
Table 3. Mass spectrum m/z 216 (65%) 214 (68, M); 185 (89)
183 (57); 107 (71) 105 (61); 77 (100, C6H5). ꢅmax (CHCl3)
369sh, 356sh, 340, 255 nm (log ꢆ 3ꢀ58, 3ꢀ84, 3ꢀ91, 4ꢀ44).
5-Bromo-2-methoxycyclohepta-2,4,6-trien-1-one (27)
Reaction of compound (5) under the conditions speciꢁed
above aꢀorded the title compound (27) (36 mg, 100%) as a pale-
yellow solid, m.p. 134–137ꢁC [lit. (1988)5 135–137ꢁC] (Found:
M+ꢃ, 213ꢀ9630. Calc. for C8H779BrO2: M+ꢃ, 213ꢀ9629).
ꢄmax (KBr) 1607, 1591, 1568, 1496, 1276, 1253 cmꢂ1
.
1H
C
14H12O2: M+ꢃ, 212ꢀ0837). ꢄmax (KBr) 1620, 1573, 1556,
n.m.r. (400 MHz) ꢀ 7ꢀ43, dd, J6,7 13ꢀ1, J6,4 2ꢀ1 Hz, 1H, H 6;
7ꢀ41, dd, J4,3 10ꢀ7, J4,6 2ꢀ0 Hz, 1H, H 4; 7ꢀ00, d, J7,6 13ꢀ1
Hz, 1H, H 7; 6ꢀ48, d, J3,4 10ꢀ7 Hz, 1H, H 3; 3ꢀ92, s, 3H,
OCH3. 13C n.m.r. (100 MHz) see Table 3. Mass spectrum m/z
216 (71%) 214 (73, M); 185 (100) 183 (61, M ꢁ CH3O); 135
(34, M ꢁ Br); 107 (35, M ꢁ CO ꢁ Br). ꢅmax (CHCl3) 379sh,
362, 329, 308sh, 256, 247 nm (log ꢆ 3ꢀ51, 3ꢀ75, 4ꢀ02, 3ꢀ98,
4ꢀ07, 4ꢀ19).
1282, 1256, 1116, 779 cmꢂ1
.
1H n.m.r. (400 MHz) ꢀ 7ꢀ54, dd,
J6,7 12ꢀ7, J6,4 2ꢀ0 Hz, 1H, H 6; 7ꢀ49–7ꢀ36, complex m, 5H,
aromatic hydrogens; 7ꢀ33, d, J7,6 12ꢀ7 Hz, 1H, H 7; 7ꢀ27, dd,
J4,3 10ꢀ3, J4,6 2ꢀ0 Hz, 1H, H 4; 6ꢀ86, d, J3,4 10ꢀ3 Hz, 1H,
H 3; 4ꢀ00, s, 3H, OCH3. 13C n.m.r. (100 MHz) ꢀ 179ꢀ8, 164ꢀ2,
142ꢀ1, 141ꢀ6, 138ꢀ0, 137ꢀ0, 131ꢀ2, 128ꢀ9, 128ꢀ0, 127ꢀ3, 112ꢀ8,
56ꢀ3. Mass spectrum m/z 212 (100%, M); 184 (25, M ꢁ CO);
183 (53, M ꢁ H ꢁ CO); 181 (34, M ꢁ OCH3); 141 (45); 115
(45). ꢅmax (CHCl3) 337, 245 nm (log ꢆ 4ꢀ25, 4ꢀ33).
6-Bromo-2-methoxycyclohepta-2,4,6-trien-1-one (31)
Reaction of compound (7) under the conditions speciꢁed
above aꢀorded the title compound (31) (33 mg, 92%) as a pale-
yellow solid, m.p. 129–131ꢁC (lit.24 129ꢀ5–131ꢀ5ꢁC) (Found:
M+ꢃ, 213ꢀ9630. Calc. for C8H779BrO2: M+ꢃ, 213ꢀ9629).
1H n.m.r. (400 MHz) ꢀ 7ꢀ68, d, J7,5 2ꢀ0 Hz, 1H, H 7; 7ꢀ09,
ddd, J5,4 11ꢀ2, J5,7 2ꢀ0, J5,3 0ꢀ5 Hz, 1H, H 5; 6ꢀ81, dd, J4,3
10ꢀ3, J4,5 11ꢀ1 Hz, 1H, H 4; 6ꢀ61, br d, J3,4 10ꢀ0 Hz, 1H,
H 3; 3ꢀ93, d, J 0ꢀ7 Hz, 3H, OCH3. 13C n.m.r. (100 MHz) see
Table 3. Mass spectrum m/z 216 (59%) 214 (59, M); 185 (74)
183 (50, M ꢁ OCH3); 92 (44); 77 (100) (C6H5). ꢅmax (CHCl3)
367sh, 353, 340sh, 326sh, 314sh, 254sh, 250 nm (log ꢆ 3ꢀ48,
3ꢀ73, 3ꢀ80, 3ꢀ84, 3ꢀ78, 4ꢀ36, 4ꢀ38).
2-Methoxy-6-phenylcyclohepta-2,4,6-trien-1-one (24)
The C-stannylated troponoid (7) (100 mg, 0ꢀ33 mmol)
was cross-coupled with bromobenzene in the same manner
as described immediately above for the conversion (5) →
(23). Workup provided a yellow oil which was subjected to
semipreparative h.p.l.c. (ethyl acetate elution; ꢃow rate 2ꢀ0
ml/min) and concentration of the single major fraction (Rt 625
s) gave the title compound (24) (40 mg, 56%) as light-yellow
ꢄmax (KBr) 1605, 1589, 1573, 1496, 1443, 1281, 1227 cmꢂ1
.
microcrystals, m.p. 114–115ꢁC (lit.23 115ꢁC) (Found: M+ꢃ
,
212ꢀ0837. Calc. for C14H12O2: M+ꢃ, 212ꢀ0837). ꢄmax (KBr)
1619, 1592, 1579, 1566, 1470, 1231, 760 cmꢂ1 1H n.m.r. (400
.
MHz) ꢀ 7ꢀ54–7ꢀ38, complex m, 6H; 7ꢀ14–7ꢀ06, complex m,
2H; 6ꢀ72, dd, J 8ꢀ0, J 2ꢀ7 Hz, 1H, H 3; 3ꢀ96, s, 3H, OCH3.
13C n.m.r. (100 MHz) ꢀ 179ꢀ6, 165ꢀ2, 149ꢀ9, 142ꢀ4, 136ꢀ2,
131ꢀ9, 129ꢀ8, 128ꢀ7(8), 128ꢀ7(6), 127ꢀ7, 111ꢀ5, 56ꢀ3. Mass
spectrum m/z 212 (100%, M); 184 (44, M ꢁ CO); 183 (35,
M ꢁ H ꢁ CO); 181 (30, M ꢁ CH3O); 154 (33); 141 (39). ꢅmax
(CHCl3) 370sh, 356sh, 277 nm (log ꢆ 3ꢀ57, 3ꢀ75, 4ꢀ42).
Generalized Procedure for the Reaction of Stannylated
Troponoids (3), (5) and (7) with Deuterium Chloride.
Formation of Compounds (26), (28) and (32)
A magnetically stirred solution of the appropriate troponoid
(50 mg, 0ꢀ17 mmol) in CD3OD (0ꢀ5 ml) was treated with
DCl (33 ꢁl of a 20% wt solution in D2O, 0ꢀ20 mmol) and
the resulting mixture was stirred at room temperature for 16
h. The reaction mixture was then poured into water (10 ml)
and extracted with CH2Cl2 (3ꢂ15 ml). The combined organic
phases were washed with water (2ꢂ10 ml) then dried (MgSO4),
ꢁltered and concentrated under reduced pressure. The residue
was subjected to preparative t.l.c. (1 : 1 CH2Cl2/Et2O elution)
and the major chromophoric band (RF 0ꢀ4) was extracted (1 : 1
CH2Cl2/Et2O) to give the appropriate deuterated troponoid.
Reactions of Stannylated Troponoids (2)–(8) with
Electrophiles
Generalized Procedure for the Reaction of Stannylated
Troponoids (3), (5) and (7) with Pyridinium Hydrobromide
Perbromide. Formation of Compounds (25), (27) and (31)
Pyridinium hydrobromide perbromide (53 mg, 0ꢀ17 mmol)
was added to a magnetically stirred solution of the appropriate
stannane (50 mg, 0ꢀ17 mmol) in CH2Cl2 (3 ml) maintained
under a nitrogen atmosphere. The ensuing yellow solution was
stirred at 0ꢁC for 30 min and then at room temperature for
16 h. The resulting pale-yellow reaction mixture was then
poured into water (15 ml) and the phases were separated. The
aqueous phase was extracted with CH2Cl2 (2ꢂ15 ml) and the
combined organic phases were washed with HCl (2ꢂ20 ml of a
2 M aqueous solution) then water (2ꢂ20 ml) before being dried
(MgSO4), ꢁltered and concentrated under reduced pressure to
aꢀord the appropriate brominated troponoid.
2-Methoxy(4-2H)cyclohepta-2,4,6-trien-1-one (26)
Treatment of compound (3) with DCl under the conditions
deꢁned above aꢀorded a white solid which was recrystallized
(Et2O) to give the title compound (26) (15 mg, 65%) as
a crystalline solid, m.p. 35–37ꢁC (Found: M+ꢃ, 137ꢀ0587.
C81H72HO2 requires: M+ꢃ, 137ꢀ0587). ꢄmax (KBr) 2920,
1619, 1589, 1561, 1555, 1463, 1280, 1219 cmꢂ1 1H n.m.r. (400
.
MHz) ꢀ 7ꢀ28, m, 2H; 6ꢀ90, m, 1H; 6ꢀ76, br s, 1H, H 3; 3ꢀ97,
d, J 0ꢀ7 Hz, 3H, OCH3. 13C n.m.r. (100 MHz) see Table 4.
Mass spectrum m/z 137 (72%, M); 108 (48, M ꢁ H ꢁ CO); 106
(100, M ꢁ CH3O). ꢅmax (CHCl3) 352sh, 344sh, 332sh, 321sh,
310sh, 246 nm (log ꢆ 3ꢀ32, 3ꢀ64, 3ꢀ72, 3ꢀ78, 3ꢀ73, 3ꢀ98).
4-Bromo-2-methoxycyclohepta-2,4,6-trien-1-one (25)
Reaction of compound (3) with pyridinium hydrobromide
perbromide according to the generalized procedure aꢀorded the
title compound (25) (28 mg, 78%) as a pale-yellow solid, m.p.
116–118ꢁC (lit.24 m.p. 117–118ꢁC) (Found: M+ꢃ, 213ꢀ9629.
Calc. for C8H779BrO2: M+ꢃ, 213ꢀ9629). ꢄmax (KBr) 1624,
2-Methoxy(5-2H)cyclohepta-2,4,6-trien-1-one (28)
Treatment of compound (5) with DCl under the conditions
deꢁned above aꢀorded a white solid which was recrystallized
(Et2O) to give the title compound (28) (16 mg, 70%) as
a crystalline solid, m.p. 38–39ꢁC (Found: M+ꢃ, 137ꢀ0583.
1573, 1251, 1221, 1174, 884, 824 cmꢂ1 1H n.m.r. (400 MHz) ꢀ
.
7ꢀ21, ddd, J 9ꢀ1, 1ꢀ5, 0ꢀ7 Hz, 1H, H 5; 7ꢀ10, dd, J 11ꢀ9, 0ꢀ7