SnCl4-catalyzed reaction of o-benzoquinones and aryl acetylenes: An unprecedented one-pot synthesis of tropone derivatives

Article abstract of DOI:10.1021/jo016098x

Highly substituted tropone derivatives were obtained as a result of SnCl₄-catalyzed cycloaddition of 3-methoxy-substituted o-benzoquinones with aryl acetylenes and subsequent rearrangement of the adducts with concomitant decarbonylation.

Full text of DOI:10.1021/jo016098x

4
Sn Cl -Ca ta lyzed Rea ction of
o-Ben zoqu in on es a n d Ar yl Acetylen es: An
Un p r eced en ted On e-P ot Syn th esis of
Tr op on e Der iva tives
Vijay Nair,*,† D. Sethumadhavan, Smitha M. Nair,
†
†
‡
§
Nigam P. Rath, and Guenter K. Eigendorf
Organic Chemistry Division, Regional Research Laboratory
F IGURE 1.
SCHEME 1
(CSIR), Trivandrum-695019, India, Department of
Chemistry, University of MissourisSt. Louis, Missouri
3121-4499,and Department of Chemistry, The University of
British Columbia, Vancouver, V6T 1Z1, Canada
6
vijaynair_2001@yahoo.com
Received September 8, 2001
Abstr a ct: Highly substituted tropone derivatives were
obtained as a result of SnCl4-catalyzed cycloaddition of
absorption at 1686 cm- . In the H NMR spectrum, the
singlet due to the methoxy protons was present at δ 2.99.
The benzylic protons were discernible at δ 5.93 and 6.10
as singlets. In the 13C NMR spectrum, benzylic carbons
resonated at δ 51.23 and 52.52. The methoxy carbon
signal was visible at δ 59.94 and the carbonyl carbon at
δ 184.52. Final proof for the structure of 5 was obtained
by single-crystal X-ray analysis.
1
1
3
-methoxy-substituted o-benzoquinones with aryl acetylenes
and subsequent rearrangement of the adducts with con-
comitant decarbonylation.
The chemistry of o-quinones, especially their cyclo-
1
additions, has been the subject of considerable interest.
Our own studies have uncovered novel facets of the
2
Although the reaction did not proceed along the
expected lines, the facility of the reaction and the interest
in tropones and tropolones prompted us to explore the
cycloadditions of o-quinones. A reaction of particular
interest has been the Diels-Alder cycloaddition of o-
benzoquinones and aryl acetylenes leading to bicyclo-
7
chemistry further. In this context, it is noteworthy that
there are only two useful methods available for the
conversion of o-benzoquinones to tropone derivatives, viz.,
the reaction of bismuthonium ylides with quinones and
the Lewis acid-promoted rearrangement of homo-o-ben-
zoquinones to R-tropolones;8b the homo-o-benzoquinones
themselves are obtained by a multistep process from
cyclohexadiene derivatives.
[2.2.2]octenediones; the latter have been shown to un-
dergo facile photolytic decarbonylation, thus constituting
3
an efficient synthesis of polysubstituted aromatics. Dur-
8
a
ing the course of some related investigations, we encoun-
tered a novel tropone synthesis, and it is described here.
Our investigations commenced with an attempt at the
Diels-Alder cycloaddition of quinone 1 with phenylacety-
lene. In the event, bicycloadducts 2 and 3 (Figure 1) were
obtained albeit in very low yields; the major product was
a dimer of quinone 1.
4
The SnCl -catalyzed cycloaddition of o-quinones was
investigated with different aryl acetylenes. Results simi-
lar to that described above were obtained, and these are
presented in Table 1.
Although the exact mechanism of the tropone forma-
tion is not known with certainty, a rationalization along
the following lines can be invoked. Conceivably the first
step will be a Lewis acid-catalyzed Diels-Alder reaction
of o-bezoquinone 1 and phenylacetylene to form the
bicyclo[2.2.2] adduct 2. This adduct can undergo a Lewis
To enhance the efficiency of the reaction, an attempt
4
was made to catalyze it with SnCl ; the catalytic effect
4
of Lewis acids in Diels-Alder reactions is well-known
5
since the original work of Yates and Eaton. A facile
reaction occurred, but to our surprise the major product
formed was a tropone derivative 5 (Scheme 1). The [3.2.1]
adduct 6 was obtained as a minor product; formation of
has precedence in our earlier work.6
6
The product 5 was characterized by spectroscopic
methods. IR spectrum of 5 showed a very weak carbonyl
(
4) (a) Santelli, M and Pons, J .-M. In Lewis Acids and Selectivity in
Organic Synthesis; CRC Press: Boca Raton, 1996; Chapter 6, pp 267-
28. (b) Danishefsky, S.; Kerwin, J . F., J r.; Kobayashi, S. J . Am. Chem.
3
*
To whom correspondence should be addressed. E-mail: gvn@
Soc. 1982, 104, 358. (c) Grieco, P. A.; Nunes, J . J .; Gaul, M. D. J . Am.
Chem. Soc. 1990, 112, 4595.(d) Kobayashi, S. Synlett 1994, 689. (e)
Kagan, H. B.; Riaut, O. Chem. Rev. 1992, 92, 1007. (f) Oppolzer, W.
Angew. Chem., Int. Ed. Engl. 1984, 23, 876. (g) Hubbard, R. D.; Miller,
B. L. J . Org. Chem. 1998, 63, 4143. (h) Nair, V.; Davis, M.; Treesa, P.
M.; Rath, N. P.; Eigendorf, G. K. Synthesis 2000, 850. (I) Sinder, B.
B.; Rodini, D. J .; Conn, R. S. E.; Sealfon, S. J . Am. Chem. Soc. 1979,
101, 5283.
(5) Yates, P.; Eaton, P. J . Am. Chem. Soc. 1960, 82, 4436.
(6) Nair, V.; Anilkumar, G.; Eigendorf, G. K.; Willard, P. G.
Tetrahedron Lett. 1996, 37, 8271.
(7) Tropones and Tropolones have attracted considerable interest
due to their novel structure and presence in a number of natural
products. Consequently, a large number of methods have been devel-
oped for the synthesis of this ring system. A few selected references
are given here. (a) Silverton, J . V.; Kabuto, C.; Buk, K. T.; Cava, M. P.
csrrltrd.ren.nic.in, Fax: 91-471-491712.
†
Regional Research Laboratory (CSIR).
University of MissourisSt. Louis.
The University of British Columbia.
‡
§
(1) Finley, K. T. In The Chemistry of Quininoid Compounds, Patai.
S.; Rappoport, Z., Eds.; J ohn Wiley & Sons: New York, 1988; Vol. 2,
pp 636-645.
(2) (a) Nair, V.; Kumar, S. Synlett 1996, 1143 and references cited
therin. (b) Nair, V.; Kumar, S. J . Chem. Soc., Chem. Commun. 1994,
341. (c).Nair, V.; Kumar, S.; Willard, P. G. Tetrahedron Lett. 1995,
5, 1605. (d). Nair, V.; Kumar, S.; Rath, N. P.; Morton, G. O. Chem.
Lett. 1995, 383. (e) Nair, V.; Kumar, S.; Anilkumar, S.; Nair, J . S.
Tetrahedron 1995, 51, 9155. (f) Nair, V.; Kumar, S. J . Chem. Soc.,
Perkin Trans.1 1996, 443.
1
3
(3) Thomas, A.; Anilkumar, G.; Nair, V. Tetrahedron 1996, 52, 2481.
1
0.1021/jo016098x CCC: $22.00 © 2002 American Chemical Society
Published on Web 09/14/2002
J . Org. Chem. 2002, 67, 7533-7536
7533

TABLE 1: Rea ction of O-ben zoqu in on es 1, 7, a n d 8 w ith Ar yl Acetylen es 4-f
SCHEME 2
SCHEME 3
6
acid-catalyzed rearrangement to form a [3.2.1] adduct
7, which spontaneously eliminates a molecule of carbon
monoxide to form the tropone derivative 5 (Scheme 2).
The above mechanistic pathway was supported by the
following findings. We treated the adducts 2 and 3
In conclusion, we have uncovered a simple and efficient
one-pot synthesis of highly substituted tropone deriva-
tives.
2
Exp er im en ta l Section
independently with SnCl
was found that 2 was converted to 5 exclusively, whereas
produced only 6. Also the [3.2.1] adduct 6, when heated
4
under identical conditions. It
3
-Methoxycatechol, montmorillonite K-10, sodium periodate,
3
and tin(IV) chloride were purchased. Aryl acetylenes used in the
above its melting point, eliminated a molecule of CO to
9
experiments were either purchased or synthesized.
form another tropone derivative 28 which is isomeric with
Exp er im en ta l P r oced u r e for th e Syn th esis of Qu in on e
1. 3-Methoxycatechol (2 g, 0.014 mol) and benzhydrol (5.78 g,
0.031 mol) were dissolved in dry dichloromethane (30 mL). To
this mixture, 5.78 g of montmorillonite K-10 (pre heated to 80
5
6
(Scheme 3). The ease of decarbonylation of 27 vis a vis
may be attributed to the release of steric strain in the
former.
°
C and cooled under moisture free conditions) was added and
stirred for 12 h. The reaction mixture was then filtered, and the
filtrate was subjected to silica gel column chromatography using
hexane-ethyl acetate mixture (85:15) to afford the substituted
catechol (4.85 g, 72%). To this catechol (dissolved in 20 mL
dichloromethane) was added a solution of sodium periodate (6.6
g, 0.030 mol in 20 mL water) and stirred for 10 h. The two layers
were separated, and the water layer was extracted with dichlo-
romethane (10 mL × 2). The combined extracts were dried over
sodium sulfate and subjected to silica gel column chromatogra-
phy using hexane-ethyl acetate mixture to afford the quinone
1 (3.86 g, 80%).
J . Am. Chem. Soc. 1977, 99, 6708. (b) Boger, D. L.; Brotherton, C. E.
J . Am. Chem. Soc. 1986, 108, 6713. (c) Nair, V.; Powell, D. W.; Suri,
S. C. Synth. Commun. 1987, 17, 1897. (d) Suri, S. C.; Nair, V. Synthesis
1
990, 695. (e) Davies, H. M. L.; Clark, T. J .; Kimmer, G. F. J . Org.
Chem. 1991, 56, 6440 and references therein. (f) Banwell, M. G.;
Corbett, M.; Mackay, M. F.; Richards, S. L. J . Chem. Soc., Perkin Trans.
1
1992, 1329. (g) Boger, D. L.; Zhu, Y. J . Org. Chem. 1994, 59, 1329.
(h) Dygutsch, D. P.; Neumann, W. P.; Peterseim, M. Synlett 1994, 1329.
i) Lee, J . C.; J in, S.; Cha, J . K. J . Org. Chem. 1998, 63, 2804.(j)
(
Nenajdenko, V. G.; Baraznenok, I. L.; Balenkova, E. S.; J . Org. Chem.
1
1
998, 63, 6132. (k) Lee, J . C.; Cho, S. Y.; Cha, J . K. Tetrahedron Lett.
999, 40, 7675. (l) Sendelbach, S.; Schwetzler-Raschke, R.; Radl, A.;
Kaiser, R.; Henle, G. H.; Korfant, H.; Reiner, S.; Fohlisch, B. J . Org.
Chem, 1999, 64, 3398.
(
8) (a) Rahman, M. M.; Matano, Y.; Suzuki, H.; J . Chem. Soc., Perkin
(9) (a) Muller, S.; Liepold, B.; Roth, G. J .; Bestman, H. J . Synlett
1996, 521. (b) Wang, Z.; Yin, J .; Campagna, S.; Pesti, J . A.; Fortunak,
J . M. J . Org. Chem. 1999, 64, 6918.
Trans. 1 1999, 1533. (b) Banwell, M. G.; Collis, M. P. J . Chem. Soc.,
Chem. Commun. 1991, 1343.
7
534 J . Org. Chem., Vol. 67, No. 21, 2002

Sp ectr a l Da ta for th e Qu in on e 1. Dark brown solid; mp:
7-49 °C; IR (KBr) νmax: 700, 745, 979, 1064, 1309, 1449, 1493,
600, 1666, 3026, 3059 cm-1; H NMR: δ 3.81(s, 3H), 5.40 (s,
H), 5.73 (s, 1H), 6.38 (d, 1H, J ) 1.2 Hz), 6.91-7.00 (m, 8H),
.15-7.26 (m, 12H). 13C NMR: δ 48.19, 49.03, 60.41, 126.59,
27.10, 127.92, 128.34, 128.58, 128.64, 128.69, 137.77, 139.76,
40.41, 140.58, 140.85, 148.50, 176.95, 178.46. HRMS Calcd for
1582, 1614, 1686, 2867, 2961 cm-1; 1H NMR: δ 1.27 (m, 18H),
4
1
1
7
1
1
1.31 (m, 18H), 3.02 (s, 3H), 5.89 (s, 1H), 5.98 (s, 1H), 6.70-6.74
1
13
(m, 8H), 6.90 (s, 1H), 7.07 (s, 1H), 7.16-7.42 (m, 13H);
C
NMR: δ 26.92, 31.44, 34.32, 34.40, 50.50, 51.65, 60.07, 125.01,
125.25, 128.03, 128.14, 128.93, 129.03, 129.09, 139.28, 139.43,
140.44, 141.07, 146.75, 148.68, 149.17, 151.29, 157.85, 184.19.
Anal. Calcd for C56
H, 8.45.
64 2
H O : C, 87.45; H, 8.39. Found: C, 87.19;
C
33
H
26
O
3
: 470.1882. Found: 470.1876.
Exp er im en ta l P r oced u r e for th e Syn th esis of Tr op on e
1,6-Bis(b is(4-t er t -b u t ylp h e n yl)m e t h yl)-5-m e t h oxy-3-
ph en ylbicyclo[3.2.1]oct-3,6-dien e-2,8-dion e 19. Colorless crys-
tals, recrystallized from hexane-dichloromethane; mp: 194-
196 °C; IR (KBr) νmax: 820, 1138, 1257, 1432, 1512, 1688, 1769,
2962 cm ; H NMR: δ 1.21 (s, 9H), 1.26 (s, 9H), 1.33 (s, 9H),
1.34 (s, 9H), 3.52 (s, 3H), 4.55 (s, 1H), 4.90, (s, 1H), 5.70, (s, 1H),
6.43, (s, 1H), 6.71-7.24 (m, 21H); 13C NMR: δ 31.27, 31.30,
31.38, 34.10, 34.35, 48.03, 52.88, 55.27, 64.93, 99.18, 124.30,
124.62, 124.84, 125.38, 126.20, 126.36, 127.57, 127.92, 128.42,
128.55, 129.38, 130.78, 136.05, 136.24, 136.39, 137.70, 137.77,
137.91, 147.08, 148.42, 149.01, 149.28, 149.63, 165.47, 188.47,
Der iva tives a n d Bicycloa d d u cts. The general procedure for
the synthesis of tropone derivatives and bicycloadducts is
exemplified by the synthesis of 5 and 6. To a stirred mixture of
-
4
-1 1
o-benzoquinone 1 (0.20 g, 4.25 × 10 mol) and phenylacetylene
-
4
(
0.052 g, 5.10 × 10 mol) in dry dichloromethane (2 mL) was
added SnCl (0.851 mL, 1 molar solution of SnCl in heptane)
4
4
and stirred for 2 h under an atmosphere of argon at room
temperature. The reaction mixture was then quenched with
water (5 mL) and extracted with dichloromethane (2 × 10 mL).
The organic extract was concentrated and the crude product
subjected to column chromatography on silica gel using hexane-
ethyl acetate mixture (90:10) to afford the tropone derivative 5
198.02. Anal. Calcd for C57
86.06; H, 8.31.
64 3
H O : C, 85.89; H, 8.09. Found: C,
(
0.139 g, 60%) and the [3.2.1] adduct 6 (0.044 g, 18%). Tropone
4-Meth oxy-3-(4-m eth ylp h en yl)-5,7-bis(d ip h en ylm eth yl)-
2,4,6-cycloh ep ta tr ien -1-on e 11. Pale yellow crystals, recrys-
tallized from hexane-ethyl acetate; mp: 160-162 °C; IR (KBr)
derivative 14 and bicycloadduct 23 were separated by column
chromatography using hexane-dimethoxyethane (95:5) mixture.
Sp ectr a l Da ta for Tr op on e Der iva tives a n d Bicycloa d -
d u cts. 4-Methoxy-3-phenyl-5,7-bis(diphenyl methyl)-2,4,6-cy-
cloheptatrien-1-one 5. Pale yellow crystals, recrystallized from
hexane-dichloromethane; mp: 200-202 °C; IR (KBr) νmax: 689,
ν
max: 699, 743, 994, 1153, 1368, 1447, 1492, 1572, 1601, 1689,
-
1 1
2931, 3024 cm ; H NMR: δ 2.38 (s, 3H), 2.99 (s, 3H), 5.93 (s,
1H), 6.09 (s, 1H), 6.84-6.87 (m, 8H), 6.93 (s, 1H), 7.06 (s, 1H),
7.12-7.36 (m, 16 H); 13C NMR: δ 21.32, 51.36, 52.63, 60.01,
126.32, 126.59, 128.29, 128.54, 128.90, 129.06, 129.27, 129.33,
137.36, 138.06, 138.25, 140.30, 140.59, 142.34, 142.42, 146.89,
7
52, 989, 1151, 1201, 1439, 1489, 1551, 1686, 2930, 3030 cm-1
;
1
H NMR: δ 2.99 (s, 3H), 5.93 (s, 1H), 6.10 (s, 1H), 6.84-6.85
m, 5H), 6.95 (s, 1H), 7.07 (s, 1H), 7.13-7.45 (m, 20 H); 13
NMR: δ 51.23, 52.52, 59.94, 126.22, 126.49, 128.06, 128.18,
(
C
151.00, 158.44, 184.71; HRMS Calcd for C41
Found: 558. 2553.
34 2
H O : 558.2558.
1
1
28.43, 129.00, 129.13, 129.20, 138.11, 140.09, 140.26, 140.66,
42.15, 142.24, 146.81, 150.99, 158.12, 184.52. Anal. Calcd for
1,6-Bis(d ip h en ylm eth yl)-5-m eth oxy-3-(4-m eth ylp h en yl)-
bicyclo[3.2.1]oct-3,6-d ien e-2,8-d ion e 20. Pale yellow crystals,
recrystallized from hexane-ethyl acetate; mp: 167-169 °C; IR
(KBr) νmax: 689, 1022, 1146, 1177, 1448, 1493, 1686, 1775, 2947,
C
40
H
32
O
2
: C, 88.20: H, 5.92. Found C, 88.28; H, 6.04.
,6-Bis(d ip h e n ylm e t h yl)-5-m e t h oxy-3-p h e n ylb icyclo-
3.2.1]oct-3,6-d ien e-2,8-d ion e 6. Colorless crystals, recrystal-
lized from hexane-dichloromethane; mp: 132-134 °C; IR (KBr)
1
-
1 1
[
3025 cm ; H NMR: δ 2.24 (s, 3H), 3.53 (s, 3H), 4.71 (s, 1H),
4.96 (s, 1H) 5.71 (s, 1H), 6.39 (s, 1H), 6.80-6.97 (m, 13 H), 7.22-
-
1
1
13
ν
max: 1032, 1151, 1238, 1438, 1494, 1669, 1781, 2949 cm . H
7.24 (m, 11 H); C NMR: δ 21.15, 49.18, 53.24, 55.32, 64.51,
NMR: δ 3.54 (s, 3H), 4.67 (s, 1H), 4.97 (s, 1H), 5.72 (s, 1H), 6.41
99.22, 125.92, 126.02, 126.31, 126.55, 126.87, 127.26, 127.64,
128.15, 128.51, 128.64, 128.83, 129.21, 129.65, 130.77, 134.63,
137.30, 138.37, 138.44, 139.23, 139.62, 140.30, 147.11, 165.37,
(s, 1H), 6.80-6.87 (m, 4H), 6.96-6.98 (m, 8H), 7.05-7.13 (m,
4
9
1
1
1
8
H), 7.21-7.24 (m, 9H); 13C NMR: δ 49.29, 53.61, 55.53, 64.69,
9.29, 126.09, 126.45, 126.68, 126.99, 127.38, 127.73, 127.93,
28.27, 128.43, 128.77, 128.96, 129.32, 129.81, 130.86, 137.49,
37.58, 138.57, 139.31, 139.53, 140.42, 147.40, 165.25, 188.54,
188.51, 197.92. Anal. Calcd for C42
Found: C, 85.92; H, 6.04.
34 3
H O : C, 85.98; H, 5.84.
4-Me t h oxy-3-(4-m e t h ylp h e n yl)-5,7-b is(b is(4-m e t h yl-
p h en yl)m eth yl)-2,4,6-cycloh ep ta tr ien -1-on e 12. Pale yellow
crystals, recrystallized from hexane-ethyl acetate; mp: 83-85
°C; IR (KBr) νmax: 766, 996, 1153, 1204, 1368, 1510, 1572, 1594,
98.00. Anal. Calcd for C41
6.26; H, 5.85.
32 3
H O : C, 85.99; H, 5.63. Found: C,
4
-Meth oxy-3-ph en yl-5,7-bis(bis(4-m eth ylph en yl)m eth yl)-
-
1
1
2
,4,6-cycloh ep ta tr ien -1-on e 9. Pale yellow crystals, recrystal-
1611, 2921, 3020 cm ; H NMR: δ 2.31 (s, 6H), 2.35 (s, 6H),
2.40 (s, 3H), 3.00 (s, 3H), 5.85 (s, 1H), 6.03 (s, 1H), 6.74-6.76
lized from hexane-dichloromethane; mp: 189-191 °C; IR (KBr)
1
3
ν
1
2
7
max: 764, 805, 996, 1153, 1242, 1370, 1445, 1510, 1576, 1613,
683, 2921, 3020 cm-1; H NMR: δ 2.29 (s, 6H), 2.33 (s, 6H),
.97 (s, 3H), 5.83 (s, 1H), 6.00 (s, 1H), 6.72-6.76 (m, 8H), 6.92-
(m, 4H), 6.94-7.38 (m, 14H), 7.06 (s, 1H), 7.20 (s, 1H);
C
1
NMR: δ 21.10, 21.29, 50.62, 51.98, 59.98, 128.87, 129.08, 129.13,
129.16, 135.44, 135.82, 137.46, 138.09, 138.49, 139.58, 139.64,
140.16, 140.40, 146.83, 151.29, 158.11, 184.82. Anal. Calcd for
.00 (m, 8H), 7.04 (s, 1H), 7.25 (s, 1H), 7.36-7.45 (m, 5H); 13
C
NMR: δ 21.02, 50.52, 51.89, 59.94, 128.00, 128.14, 128.79, 129.01,
C
45
H
42
O
2
: C; 87.91; H; 6.89. Found: C; 87.68, H; 7.15.
1
1
H
29.07, 135.38, 135.76, 138.55, 139.42, 139.49, 140.13, 140.23,
40.49, 146.77, 151.31, 157.82, 184.68. Anal. Calcd for C44
1,6-Bis(b is(4-m e t h ylp h e n yl)m e t h yl)-5-m e t h oxy-3-(4-
-
m eth ylp h en yl)bicyclo[3.2.1]oct-3,6-d ien e-2,8-d ion e 21. Col-
orless crystals, recrystallized from hexane-dichloromethane;
mp: 120-122 °C; IR (KBr) νmax: 807, 1020, 1145, 1245, 1439,
40
O
2
: C; 87.96; H; 6.71. Found: C; 88.05, H, 6.69.
1
,6-B i s (b i s (4-m e t h y lp h e n y l)m e t h y l)-5-m e t h o x y -3-
-
1
1
ph en ylbicyclo[3.2.1]oct-3,6-dien e-2,8-dion e 18. Colorless crys-
tals, recrystallized from hexane-dichloromethane; mp: 177-
1676, 1776, 2987 cm ; H NMR: δ 2.20 (s, 3H), 2.25 (s, 3H),
2.27 (s, 3H), 2.35 (s, 3H), 2.36 (s, 3H), 3.52 (s, 3H), 4.64 (s, 1H),
4.87 (s, 1H), 5.70 (s, 1H), 6.36 (s, 1H), 6.66 (d, 2H, J ) 7.8 Hz),
1
2
3
6
2
1
1
1
79 °C; IR (KBr) νmax: 746, 1151, 1259, 1438, 1510, 1680, 1781,
-
1 1
13
937 cm ; H NMR: δ 2.19 (s, 3H), 2.28 (s, 3H), 2.35 (s, 3H),
6.75-7.10 (m, 18 H); C NMR: δ 20.97, 21.11, 21.16, 21.27,
.54 (s, 3H), 4.60 (s, 1H), 4.88 (s, 1H), 5.71 (s, 1H), 6.39 (s, 1H),
48.45, 52.23, 55.41, 64.53, 99.36, 125.98, 126.42, 128.31, 128.41,
128.51, 128.78, 128.83, 129.08, 129.39, 129.49, 130.66, 134.86,
135.24, 135.75, 135.92, 136.27, 136.54, 136.63, 137.13, 137.25,
137.66, 138.43, 147.15, 165.72, 188.83, 198.05. Anal. Calcd for
1
3
.67-6.88 (m, 10H), 6.99-7.09 (m, 11H); C NMR: δ 21.06,
1.25, 48.58, 52.65, 55.60, 64.73, 99.42, 126.41, 126.51, 127.90,
28.46, 128.57, 128.90, 128.95, 129.20, 129.51, 129.68, 130.00,
35.36, 135.86, 136.02, 136.35, 136.60, 136.73, 136.97, 137.39,
37.77, 137.80, 147.48, 165.53, 188.83, 198.11. Anal. Calcd for
C
46
H
42
O
3
: C, 85.95; H, 6.59. Found: C, 86.24; H, 6.70.
4-Met h oxy-3-(4-m et h ylp h en yl)-5,7-b is(b is(4-ter t-b u t yl-
C
45
H
40
O
3
: C, 85.95; H, 6.41. Found: C, 86.13; H, 6.59.
p h en yl)m eth yl)-2,4,6-cycloh ep ta tr ien -1-on e 13. Pale yellow
crystals, recrystallized from hexane-ethyl acetate; mp: 115-
117 °C; IR (KBr) νmax: 996, 1018, 1109, 1268, 1364, 1406, 1510,
4
-Met h oxy-3-p h en yl-5,7-b is(b is(4-ter t-b u t ylp h en yl)m e-
th yl)-2,4,6-cycloh ep ta tr ien -1-on e 10. Pale yellow crystals,
recrystallized from hexane-ethyl acetate; mp: 130-132 °C; IR
-
1
1
1573, 1610, 1685, 2878, 2903 cm ; H NMR: δ 1.26 (s, 18H),
(KBr) νmax: 575, 699, 821, 997, 1018, 1155, 1268, 1364, 1508,
1.31 (s, 18H), 2.37 (s, 3H), 3.02 (s, 3H), 5.88 (s, 1H), 5.98 (s, 1H),
J . Org. Chem, Vol. 67, No. 21, 2002 7535

6
.90-6.74 (m, 7H), 6.87 (s, 1H), 7.05 (s, 1H), 7.15-7.35 (m, 13H);
C NMR: δ 21.30, 26.95, 31.46, 34.35, 34.43, 50.51, 51.64, 60.07,
25.02, 125.26, 128.78, 128.95, 129.05, 137.60, 137.99, 139.08,
39.33, 139.49, 140.94, 141.08, 147.04, 148.67, 149.16, 151.45,
1H), 6.13 (s, 1H), 6.85-6.89 (m, 8H), 6.98 (s, 1H), 7.13-7.22 (m,
1
3
13
13H), 7.36-7.65 (m, 9H); C NMR: δ 51.25, 52.60, 60.11, 126.26,
1
1
1
7
126.51, 126.72, 126.97, 127.56, 128.21, 128.45, 128.78, 129.14,
129.18, 129.44, 138.19, 139.00, 140.15, 140.32, 140.43, 141.07,
142.15, 142.22, 146.56, 150.95, 158.23, 184.74. Anal. Calcd for
58.06, 184.27; HRMS Calcd for C57
82.50568.
66 2
H O : 782.50628; Found:
C
46
H
36
O
2
: C, 89.00; H, 5.85. Found: C, 88.78; H, 5.68.
1
,6-Bis(b is(4-ter t-b u t ylp h en yl)m et h yl)-5-m et h oxy-3-(4-
1
,6-Bis(d ip h en ylm eth yl)-5-m eth oxy-3-(4-p h en ylp h en yl)-
m eth ylp h en yl)bicyclo[3.2.1]oct-3,6-d ien e-2,8-d ion e 22. Col-
orless crystals, recrystallized from hexane-dichloromethane;
mp: 203-205 °C; IR (KBr) νmax: 578, 825, 1149, 1269, 1363,
1
1
4
bicyclo[3.2.1]oct-3,6-d ien e-2,8-d ion e 25. Colorless crystals,
recrystallized from hexane-ethyl acetate; mp: 166-168 °C; IR
(
3
5
KBr) νmax: 837, 1031, 1150, 1449, 1493, 1599, 1679, 1775, 3029,
510, 1692, 1770, 2867, 2961 cm-1
;
1
H NMR: δ 1.21 (s, 9H).
-
1 1
057 cm ; H NMR: δ 3.54 (s, 3H), 4.72 (s, 1H), 4.99 (s, 1H),
.79 (s, 1H), 6.48 (s, 1H), 6.84-6.87 (m, 2H), 6.92-7.03 (m, 8H),
.26 (s, 9H), 1.30 (s, 9H), 1.33 (s, 9H), 2.23 (s, 3H), 3.49 (s, 3H),
.58 (s, 1H), 4.89 (s, 1H), 5.69 (s, 1H), 6.43 (s, 1H), 6.72-6.74
1
3
1
3
7.23-7.48 (m, 19 H); C NMR: δ 49.31, 53.56, 55.33, 64.83,
(m, 4H), 6.83-6.97 (m, 8H), 7.13-7.23 (m, 8H); C NMR: δ
9
1
1
1
9.41, 126.05, 126.16, 126.58, 126.69, 126.83, 126.95, 126.99,
27.37, 127.65, 127.73, 127.88, 128.23, 128.74, 128.86, 128.88,
29.26, 129.78, 130.71, 136.34, 137.46, 138.24, 139.23, 139.28,
40.20, 140.28, 141.32, 147.32, 164.97, 188.51, 197.99. Anal-
2
9
1
1
1
8
1.10, 31.28, 31.38, 31.48, 34.09, 34.36, 48.16, 52.81, 55.09, 65.10,
9.44, 124.36, 124.52, 124.92, 125.44, 126.07, 126.28, 127.68,
28.31, 128.44, 128.59, 129.40, 130.27, 134.95, 135.87, 136.41,
36.46, 137.73, 138.09, 146.83, 148.44, 149.20, 149.43, 149.78,
.
Calcd for C47
4-Meth oxy-3-(2-n a p h th yl)-5,7-bis(d ip h en ylm eth yl)-2,4,6-
cycloh ep ta tr ien -1-on e 17. Pale yellow crystals, recrystallized
from hexane-ethyl acetate; mp: 192-194 °C; IR (KBr) νmax
820, 993, 1153, 1205, 1237, 1375, 1448, 1490, 1565, 1594, 1612,
36 3
H O : C, 87.01; H, 5.59. Found: C, 87.18; H, 5.71.
65.73, 188.61, 198.26. Anal. Calcd for C58
.2O. Found: C, 86.02; H, 8.44.
66 3
H O : C, 85.88; H,
4
-Met h oxy-3-(4-n -p en t ylp h en yl)-5,7-bis(d ip h en ylm et h -
yl)-2,4,6-cycloh ep ta tr ien -1-on e 14. Pale yellow crystals, re-
crystallized from pentane; mp: 103-105 °C; IR (KBr) νmax: 698,-
7
2
1
:
-
1
1
42, 994, 1030, 1152, 1205, 1368, 1447, 1492, 1571, 1594, 1613,
2999, 3023, 3059 cm ; H NMR: δ 2.98 (s, 3H), 5.98 (s, 1H),
6.14 (s, 1H), 6.87-6.89 (m, 8H), 7.00 (s, 1H), 7.14-7.24 (m, 13H),
7.50-7.59 (m, 3H), 7.83-7.89 (m, 3H), 7.96 (d, 1H, J ) 1.5 Hz);
-
1 1
952, 3024 cm . H NMR: δ 0.89 (t, 3H), 1.30-1.35 (m, 4H),
.58-1.68 (m, 2H), 2.63 (t, 2H), 2.99 (s, 3H), 5.95 (s, 1H), 6.11
(
(
s, 1H), 6.83-6.88 (m, 8H), 6.94 (s, 1H), 7.08 (s, 1H), 7.13-7.21
13
C NMR: δ 51.25, 52.58, 60.17, 126.29, 126.35, 126.54, 126.64,
1
3
m, 14H), 7.35-7.38 (m, 2H); C NMR: δ 14.01, 22.50, 30.96,
1
1
1
8
26.98, 127.45, 127.56, 128.04, 128.24, 128.48, 129.16, 129.20,
32.87, 132.97, 137.84, 138.38, 140.50, 140.89, 142.16, 142.23,
3
1
1
1.48, 35.63, 51.31, 52.65, 60.00, 126.30, 126.54, 128.20, 128.27,
28.49, 128.91, 129.26, 137.39, 138.01, 140.30, 140.45, 142.29,
42.36, 143.37, 146.99, 150.84, 158.51, 184.89. Anal. Calcd for
46.97, 151.02, 158.34, 184.74. Anal. Calcd for C44
8.86; H, 5.76. Found: C, 88.57; H, 5.93.
34 2
H O : C,
C
45
H
42
O
2
: C, 87.91; H, 6.89. Found: C, 87.66; H, 7.05.
,6-Bis(diph en ylm eth yl)-5-m eth oxy-3-(4-n -pen tylph en yl)-
bicyclo[3.2.1]oct-3,6-d ien e-2,8-d ion e 23. Colorless crystals,
recrystallized from pentane; mp: 136-138 °C; IR (KBr) νmax
68, 698, 745, 1031, 1151, 1450, 1494, 1679, 1776, 2922, 2954
1
,6-Bis(d ip h e n ylm e t h yl)-5-m e t h oxy-3-(2-n a p h t h yl)-
1
bicyclo[3.2.1]oct-3,6-d ien e-2,8-d ion e 26. Colorless crystals,
recrystallized from hexane-ethyl acetate; mp: 157-159 °C; IR
:
(
KBr) νmax: 816, 892, 1033, 1150, 1219, 1448, 1494, 1680, 1773,
6
-
1
1
-
1
1
3007, 3028, 3068 cm ; H NMR: δ 3.55 (s, 3H), 4.76 (s, 1H),
cm ; H NMR: δ 0.89 (s, 3H), 1.20-1.36 (m, 4H), 1.46-1.56
5
7
.00 (s, 1H), 5.82 (s, 1H), 6.53 (s, 1H), 6.83-7.04 (m, 10 H), 7.23-
(m, 2H), 2.48 (t, 2H), 3.52 (s, 3H), 4.71 (s, 1H), 4.97 (s, 1H), 5.74
13
.30 (m, 11H), 7.43-7.46 (m, 2H), 7.57-7.74 (m, 4H); C NMR:
(
s, 1H), 6.43 (s, 1H), 6.77-7.01 (m, 13H), 7.22-7.25 (m, 11H);
1
3
δ 49.33, 53.48, 55.35, 64.80, 99.45, 123.88,126.06, 126.10, 126.58,
C NMR: δ 14.02, 22.50, 30.93, 31.24, 35.52, 49.30, 53.47, 55.32,
4.74, 99.40, 125.92, 126.02, 126.36, 126.66, 126.91, 127.34,
27.65, 127.78, 127.94, 128.22, 128.73, 128.89, 129.27, 129.74,
30.78, 134.81, 137.55, 138.33, 139.29, 139.53, 140.34, 143.60,
1
1
26.61, 126.70, 126.84, 126.98, 127.39, 127.56, 127.67, 127.70,
27.73, 128.09, 128.26, 128.75, 128.91, 129.30, 129.6,130.71,
6
1
1
1
8
132.61, 134.83, 137.47, 138.23, 139.12, 139.44, 140.32, 147.30,
47.15, 165.46, 188.65, 198.12. Anal. Calcd for C46
5.95; H, 6.59. Found: C, 85.71; H, 6.40.
H
42
O
3
: C,
165.25, 188.49, 198.02. Anal. Calcd for C45
5.50. Found: C, 86.87; H, 5.62.
34 3
H O : C, 86.79; H,
4
-Meth oxy-3-(4-ch lor op h en yl)-5,7-bis(d ip h en ylm eth yl)-
Exp er im en ta l P r oced u r e for th e Syn th esis of Tr op on e
Der ivative 28. 4-Meth oxy-2-ph en yl-5,7-bis(diph en ylm eth yl)-
2
,4,6-cycloh ep ta tr ien -1-on e 15. Pale yellow crystals, recrys-
tallized from hexane-ethyl acetate; mp: 189-191 °C; IR (KBr)
2
,4,6-cycloh ep ta tr ien -1-on e 28. Bicycloadduct 6 (0.110 g, 2.01
10 mol) was taken in a Schlenk tube under an atmosphere
ν
1
1
7
5
1
1
max: 835, 993, 1014, 1090, 1154, 1204, 1448, 1496, 1571, 1594,
614, 3011, 3024, 3060 cm-1; H NMR: δ 3.00 (s, 3H), 5.94 (s,
H), 6.09 (s, 1H), 6.82-6.87 (m, 8H), 6.98 (s, 1H), 7.04 (s, 1H),
.14-7.24 (m, 12 H), 7.34-7.42 (m, 4H). 13C NMR: δ 51.32,
2.67, 60.20, 126.39, 126.66, 128.32, 128.43, 128.57, 129.19,
29.25, 130.45, 134.56, 138.53, 138.64, 140.52, 140.56, 142.10,
-4
×
1
of argon. It was then heated at 150 °C for 30 min. The product
obtained was subjected to column chromatography on silica gel
using hexane-ethyl acetate mixture (90:10) to afford the product
2
8 (0.099 g, 94%).
Pale yellow crystals, recrystallized from hexane-ethyl acetate;
42.17, 145.89, 151.26, 157.84, 184.63. Anal. Calcd for C40
ClO
1
bicyclo[3.2.1]oct-3,6-d ien e-2,8-d ion e 24. Colorless crystals,
recrystallized from hexane-ethyl acetate; mp: 155-157 °C; IR
KBr) νmax: 698, 749, 1090, 1151, 1448, 1492, 1593, 1678, 1776,
31
H -
mp: 152-154 °C; IR (KBr) νmax: 738, 1026, 1092, 1152, 1208,
2
: C, 82.96; H, 5.40. Found: C, 83.17; H, 5.55.
-1 1
1
441, 1487, 1571, 1613, 1697, 3024, 3061 cm ; H NMR: δ 3.82
,6-Bis(d ip h en ylm eth yl)-5-m eth oxy-3-(4-ch lor op h en yl)-
(s, 3H), 5.17 (s, 1H), 6.17 (s, 1H), 6.51-6.53 (m, 4H), 6.78 (s,
1
7
H), 6.84-6.86 (m, 4H), 6.93-6.96 (d, 1H, J ) 6.76 Hz), 7.09-
.30 (m, 16 H); 13C NMR: δ 51.60, 56.66, 59.00, 126.42, 126.53,
(
3
5
(
(
-
1
1
127.67, 127.93, 128.17, 128.26, 128.44, 129.32, 138.86, 139.64,
40.35, 141.77, 141.98, 142.24, 144.95, 151.22, 161.86, 180.68.
052 cm ; H NMR: δ 3.52 (s, 3H). 4.60 (s, 1H), 4.97 (s, 1H),
.71 (s, 1H), 6.43 (s, 1H), 6.78 (d, 2H, J ) 8.4 Hz), 6.81-6.85
1
Anal. Calcd for C40
H, 5.90.
32 2
H O : C, 88.20; H, 5.92. Found: C, 88.48;
m, 2H), 6.97-7.05 (m, 7H), 7.06 (d, 2H, J ) 8.4 Hz), 7.20-7.27
13
m, 11H); C NMR: δ 49.31, 53.56, 55.40, 64.64, 99.42, 126.31,
1
1
1
26.56, 126.76, 127.07, 127.44, 127.66, 127.71, 128.05, 128.16,
28.28, 128.78, 128.87, 129.26, 129.74, 130.71, 134.56, 135.82,
37.25, 138.20, 139.07, 140.16, 147.50, 163.98, 188.32, 197.74.
Ack n ow led gm en t. D.S. thanks the Council of Sci-
ence and Industrial Research, New Delhi, for research
fellowship.
Anal. Calcd for C41
H, 5.44.
3
H31ClO : C, 81.11; H, 5.15. Found: C, 81.38;
4
-Meth oxy-3-(4-p h en ylp h en yl)-5,7-bis(d ip h en ylm eth yl)-
Su p p or tin g In for m a tion Ava ila ble: ORTEP diagram
and X-ray data for the tropone derivative 5. This material is
available free of charge via the Internet at http://pubs.acs.org.
2
,4,6-cycloh ep ta tr ien -1-on e 16. Pale yellow crystals, recrys-
tallized from hexane-ethyl acetate; mp: 187-189 °C; IR (KBr)
ν
1
max: 844, 993, 1077, 1153, 1207, 1241, 1370, 1447, 1491, 1566,
595, 1613, 3023, 3055 cm-1; H NMR: δ 3.05(s, 3H), 5.96 (s,
1
J O016098X
7
536 J . Org. Chem., Vol. 67, No. 21, 2002