Cascade radical cyclizations of benzannulated enyne - allenes. Unusual cleavage of a benzene ring leading to twisted 1,1′-dialkyl-9,9′-bifluorenylidenes and spiro[1H-cyclobut[a]indene-1,9′-[9H]fluorenes]

Article abstract of DOI:10.1021/jo030147j

Treatment of the benzannulated enediynyl propargylic alcohol 16 (isomer ratio = 2:1) with thionyl chloride induced a sequence of reactions leading to the twisted 1,1′-dipropyl-9,9′-bifluorenylidene 17, the polycyclic compounds 18 and 19, and the spiro[1H-

Full text of DOI:10.1021/jo030147j

Ca sca d e Ra d ica l Cycliza tion s of Ben za n n u la ted En yn e-Allen es.
Un u su a l Clea va ge of a Ben zen e Rin g Lea d in g to Tw isted
1,1′-Dia lk yl-9,9′-biflu or en ylid en es a n d
Sp ir o[1H-cyclobu t[a ]in d en e-1,9′-[9H]flu or en es]
Yonghong Yang, J effrey L. Petersen,† and Kung K. Wang*
Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045
kung.wang@mail.wvu.edu
Received April 28, 2003
Treatment of the benzannulated enediynyl propargylic alcohol 16 (isomer ratio ) 2:1) with thionyl
chloride induced a sequence of reactions leading to the twisted 1,1′-dipropyl-9,9′-bifluorenylidene
17, the polycyclic compounds 18 and 19, and the spiro[1H-cyclobut[a]indene-1,9′-[9H]fluorene] 20
(trans/cis ) 5:1). The transformation from 16 to the unexpected 17 presumably involved an initial
formation of the benzannulated enyne-allene 21 followed by a C2-C6 cyclization reaction and an
intramolecular radical-radical coupling reaction, giving rise to the formal Diels-Alder adduct 23.
Repeat of this sequence then furnished 24. Cleavage of the bond connecting the two carbons having
the propyl substituent afforded 25. A subsequent rotation of the carbon-carbon bond joining the
two central five-membered rings then gave the trans isomer 26. Oxidation of 26, presumably by
oxygen, followed by hydrolysis then produced 17. Interestingly, the pathway leading to 17 involved
an unusual cleavage of a benzene ring. The X-ray crystal structure of 17 reveals that it has a twist
angle of 45.2° for the carbon-carbon double bond connecting the two bifluorenylidene fragments.
The spiro[1H-cyclobut[a]indene-1,9′-[9H]fluorene] 20 apparently was produced via two intramo-
lecular [2 + 2] cycloaddition reactions of the benzannulated enyne-allene moieties, generated in
situ from the benzannulated enediynyl propargylic alcohols. The twisted 1,1′-dimethyl-9,9′-
bifluorenylidene 33 and the spiro[1H-cyclobut[a]indene-1,9′-[9H]fluorene] 39 (trans/cis ) 3:1) were
likewise produced from 32 and 38, respectively.
In tr od u ction
way. Interestingly, in addition to 8, a minor amount of
the [2 + 2] cycloaddition adduct 9 (12%) as a derivative
of spiro[1H-cyclobut[a]indene-1,9′-[9H]fluorene] was also
isolated. This synthetic strategy was adopted for the
synthesis of a C44H26 hydrocarbon having a carbon
framework represented on the surface of C60.5 Further-
more, by employing a system containing two units of the
benzannulated enyne-allene moiety, three highly twisted
4,5-diarylphenanthrenes were obtained.6
We were interested in further exploring the use of
molecules having two benzannulated enyne-allene units
for the synthesis of polycyclic aromatic compounds. It was
quite unexpected that this strategy led to the formation
of highly twisted 1,1′-dialkyl-9,9′-bifluorenylidenes.
Because of overcrowding, the two fluorenylidene frag-
ments of 9,9′-bifluorenylidenes are severely twisted.7 The
We recently reported the use of thionyl chloride to
induce an SNi′ reaction of the benzannulated enediynyl
propargylic alcohol 2, derived from condensation between
9-fluorenone and the lithium acetylide 1 (Scheme 1).1 It
provided a convenient pathway to produce in situ the
benzannulated enyne-allene 4. A subsequent C2-C6
cyclization reaction (Schmittel cyclization) then generated
the biradical 5, which in turn underwent an intramo-
lecular radical-radical coupling to give the formal Diels-
Alder adduct 6. Tautomerization followed by hydrolysis
then afforded 8 in 74% yield. Although the transforma-
tion from 4 to 6 could also be regarded as a concerted
Diels-Alder reaction, the mechanistic,2 theoretical,3 and
DNA-cleaving4 studies suggest a two-step biradical path-
* To whom correspondence should be addressed. Phone: (304) 293-
3068, ext 6441. Fax: (304) 293-4904.
(3) (a) Engels, B.; Hanrath, M. J . Am. Chem. Soc. 1998, 120, 6356-
6361. (b) Engels, B.; Lennartz, C.; Hanrath, M.; Schmittel, M.;
Strittmatter, M. Angew. Chem., Int. Ed. 1998, 37, 1960-1963. (c)
Schreiner, P. R.; Prall, M. J . Am. Chem. Soc. 1999, 121, 8615-8627.
(d) Wenthold, P. G.; Lipton, M. A. J . Am. Chem. Soc. 2000, 122, 9265-
9270. (e) Musch, P. W.; Engels, B. J . Am. Chem. Soc. 2001, 123, 5557-
5562. (f) Stahl, F.; Moran, D.; Schleyer, P. v. R.; Prall, M.; Schreiner,
P. R. J . Org. Chem. 2002, 67, 1453-1461.
† To whom correspondence concerning the X-ray structures should
be addressed. Phone: (304) 293-3435, ext 6423. Fax: (304) 293-4904.
E-mail: jeffrey.petersen@mail.wvu.edu.
(1) Li, H.; Zhang, H.-R.; Petersen, J . L.; Wang, K. K. J . Org. Chem.
2001, 66, 6662-6668.
(2) (a) Schmittel, M.; Strittmatter, M.; Kiau, S. Angew. Chem., Int.
Ed. Engl. 1996, 35, 1843-1845. (b) Schmittel, M.; Strittmatter, M.;
Vollmann, K.; Kiau, S. Tetrahedron Lett. 1996, 37, 999-1002. (c)
Schmittel, M.; Maywald, M. Chem. Commun. 2001, 155-156. (d)
Schmittel, M.; Strittmatter, M.; Kiau, S. Tetrahedron Lett. 1995, 36,
4975-4978.
(4) Schmittel, M.; Maywald, M.; Strittmatter, M. Synlett 1997, 165-
166.
(5) Zhang, H.-R.; Wang, K. K. J . Org. Chem. 1999, 64, 7996-7999.
(6) Li, H.; Petersen, J . L.; Wang, K. K. J . Org. Chem. 2001, 66,
7804-7810.
10.1021/jo030147j CCC: $25.00 © 2003 American Chemical Society
Published on Web 06/26/2003
5832
J . Org. Chem. 2003, 68, 5832-5837

Cascade Radical Cyclizations of Benzannulated Enyne-Allenes
SCHEME 1
Resu lts a n d Discu ssion
The diketone 15 was synthesized by treatment of 138
with 4-octyne to form 14 followed by two intramolecular
acylation reactions (Scheme 2). Condensation between 15
and 2 equiv of 1 then provided the benzannulated
enediynyl propargylic alcohol 16 as a mixture of the trans
and cis isomers (isomer ratio ) 2:1). Upon treatment with
thionyl chloride, four products, including the 1,1′-dipro-
pyl-9,9′-bifluorenylidene 17, the polycyclic compounds 18
and 19, and the spiro[1H-cyclobut[a]indene-1,9′-[9H]-
fluorene] 20 as a mixture of the trans and cis isomers
(trans/cis ) 5:1), were isolated. The structures of 17, 19,
and the trans isomer of 20 were established by X-ray
structure analysis.
The formation of the products 17, 18, and 19 was
unexpected. Apparently in the case of 17, the intramo-
lecular radical-radical coupling of the initially formed
biradical 22 involved the central benzene ring having the
two propyl substituents to form 23 (Scheme 3). It was
originally anticipated that such a coupling would occur
on one of the peripheral benzene rings, which is sterically
less crowded. However, molecular modeling suggests that
this pathway suffers from nonbonded steric interactions
between the chloro substituent and the neighboring
propyl group on the central benzene ring. The effect of
such a steric interaction in dictating the course of the
reaction was observed previously.1 A second formal
intramolecular Diels-Alder reaction, again promoted by
thionyl chloride, then led to 24. Cleavage of the bond
connecting the two carbons having the propyl substituent
then gave the valence tautomer 25a , which could also
be regarded as a resonance structure of 25b having a
carbon-carbon single bond joining the two central five-
membered rings. Rotation of the carbon-carbon bond
joining the two central five-membered rings then gave
the trans isomer 26. The temperature-dependent NMR
studies have also shown that the rotational barriers of
the cis-trans isomerization of several sterically con-
gested 1,1′-disubstituted 9,9′-bifluorenylidenes are rela-
tively low, allowing rapid interconversion to occur at
ambient temperature.9 Oxidation of 26, presumably by
oxygen, followed by hydrolysis then produced 17. The
X-ray crystal structure reveals that it has a twist angle
of 45.2° for the carbon-carbon double bond connecting
the two bifluorenylidene fragments (Figure 1). This
carbon-carbon double bond has a bond length of 1.380
Å, which is unusually long for a carbon-carbon double
bond indicating a partial diradical character for the bond.
It is worth noting that transformation from 16 to 17
involves a rare occurrence of cleavage of a benzene ring.
However, the loss of the resonance energy is more than
compensated for with the eventual formation of two new
benzene rings in 17.
crystal structure of the parent compound 10a shows a
twist angle of ca. 42° while the more crowded 1,1′-
disubstituted 9,9′-bifluorenylidene 10b exhibits a higher
twist angle of ca. 52°.7a Remarkable twist angles of 55°
and 66° were recently reported for the octachlorobifluo-
renylidene 11 and the perchlorobifluorenylidene 12,
respectively.7b The reported synthetic methods for 9,9′-
bifluorenylidenes generally involve coupling of two fluo-
renyl fragments.7
The chlorosulfite 27, derived from 23, could also
undergo a different SNi′ reaction involving the carbon-
carbon double bond substituted with a propyl group to
produce the chloride 18 (Scheme 4). The structure of 18
1
was tentatively assigned on the basis of the MS and H
(7) (a) Bailey, N. A.; Hull, S. E. Acta Crystallogr., Sect. B 1978, 34,
3289-3295. (b) Molins, E.; Miravitlles, C.; Espinosa, E.; Ballester, M.
J . Org. Chem. 2002, 67, 7175-7178. (c) Ballester, M.; Castan˜er, J .;
Riera, J .; de la Fuente, G.; Camps, M. J . Org. Chem. 1985, 50, 2287-
2292. (d) Lemmen, P.; Lenoir, D. Chem. Ber. 1984, 117, 2300-2313.
(e) Lenoir, D.; Lemmen, P. Chem. Ber. 1980, 113, 3112-3119. (f)
Gosnay, I.; Bergmann, E. D.; Rabinovitz, M.; Agranat, I. Isr. J . Chem.
1972, 10, 423-437.
NMR spectra. It was observed by 1H NMR that the
(8) White, D. M. J . Org. Chem. 1974, 39, 1951-1952.
(9) (a) Gault, I. R.; Ollis, W. D.; Sutherland, I. O. Chem. Commun.
1970, 269-271. (b) Agranat, I.; Rabinovitz, M.; Weitzen-Dagan, A.;
Gosnay, I. J . Chem. Soc., Chem. Commun. 1972, 732-733.
J . Org. Chem, Vol. 68, No. 15, 2003 5833

Yang et al.
SCHEME 2
SCHEME 3
majority of 18 in the crude reaction mixture was con-
verted to 19 after purification by silica gel column
chromatography. Presumably, a 1,2-migration of the
propyl group to the adjacent carbon having a chloro
substituent occurred to give 28, which upon hydrolysis
then produced 19.
Two intramolecular [2 + 2] cycloaddition reactions with
the two chlorinated allenes derived from 16 could account
for the formation of 20 as a mixture of the trans and cis
isomers. A single crystal of the trans isomer suitable for
X-ray structure analysis was obtained.
The diketone 31 was likewise synthesized by two
intramolecular acylation reactions of 30, derived from
condensation between 13 and 1,4-dichloro-2-butyne to
form 29 followed by reduction with tributyltin hydride
(Scheme 5). Treatment of 31 with 2 equiv of 1 then
afforded the diol 32 also as a mixture of the trans and
cis isomers (isomer ratio ) 2:1). On exposure to thionyl
5834 J . Org. Chem., Vol. 68, No. 15, 2003

Cascade Radical Cyclizations of Benzannulated Enyne-Allenes
radical-radical coupling reaction involved one of the
peripheral benzene rings. Apparently, the central naph-
thyl ring with its higher resonance energy is more
resistant to being attacked at the ring junction because
such an attack would result in the loss of the entire
naphthyl aromaticity. The reaction pathway leading to
the alcohol 40 is similar to the one described for 8. It
was previously observed that treatment of the chloride
7 and other analogous compounds with NaOH under air
produced the corresponding ketones in excellent yields.11
A similar reaction could likewise give rise to the ketone
41.
Con clu sion s
The transformations from 16 and 32 to the highly
twisted 1,1′-dialkyl-9,9′-bifluorenylidenes 17 and 33,
respectively, represent a novel synthetic pathway to these
highly twisted compounds. The cascade sequence involves
an unusual cleavage of a benzene ring. Alternatively, the
intramolecular [2 + 2] cycloaddition reactions of the
benzannulated enyne-allenes lead to the spiro[1H-
cyclobut[a]indene-1,9′-[9H]fluorenes] 20 and 39-41.
F IGURE 1. ORTEP drawing of the crystal structure of the
1,1′-dipropyl-9,9′-bifluorenylidene 17 with hydrogen atoms
omitted for clarity.
SCHEME 4
Exp er im en ta l Section
Diester 14. A mixture of 0.174 g (0.500 mmol) of 2,5-
dicarbomethoxy-3,4-diphenylcyclopentadienone (13)8 and 0.10
mL (0.68 mmol) of 4-octyne in 3 mL of mesitylene in a sealed
tube was heated to 190 °C for 12 h. The solvent was removed
in vacuo. Flash column chromatography (silica gel/10% ethyl
acetate in hexanes) afforded 0.109 g of 14 (0.253 mmol, 50%)
as a waxlike white solid: mp 105-108 °C; IR 1728, 1200, 702
cm-1; 1H (270 MHz) δ 7.13-7.06 (6 H, m), 7.03-6.96 (4 H, m),
3.43 (6 H, s), 2.62 (4 H, t, J ) 8.3 Hz), 1.65 (4 H, sextet, J )
7.7 Hz), 1.02 (6 H, t, J ) 7.3 Hz); 13C (67.9 MHz) δ 170.0, 138.3,
137.0, 136.8, 136.3, 130.0, 127.3, 126.7, 51.7, 33.0, 24.9, 14.9;
MS m/z 430 (M+), 415, 399, 367, 337.
Dik eton e 15. To a flask containing 0.088 g (0.205 mmol)
of 14 was added 4 mL of concentrated sulfuric acid. The
mixture was swirled periodically until the solid was dissolved
in the sulfuric acid at rt. After 3 h, the reaction mixture was
poured into an ice-water mixture and then was extracted with
diethyl ether. The combined organic extracts were washed with
water, dried over magnesium sulfate, and concentrated. Re-
crystallization of the crude yellow solid from 95% ethanol
afforded 0.059 g of 15 (0.161 mmol, 79%) as bright-yellow
chloride, 32 was also transformed to the 1,1′-dimethyl-
9,9′-bifluorenylidene 33 and the polycyclic compounds 34
and 35. The structure of 34 was tentatively assigned on
1
the basis of the MS and H NMR spectra. Compared to
1
crystals: mp 182-184 °C; IR (KBr) 1700, 757, 721 cm-1; H
the case of 16, elimination of a molecule of hydrogen
chloride from 34 to form 35 appears to occur more readily
than 1,2-migration of the adjacent methyl group. The
structure of 35 was established by X-ray structure
analysis. The [2 + 2] cycloaddition adduct was not
detected in this case.
(270 MHz) δ 8.09 (2 H, d, J ) 7.7 Hz), 7.75 (2 H, d, J ) 7.4
Hz), 7.59 (2 H, td, J ) 7.5, 1.0 Hz), 7.38 (2 H, t, J ) 7.4 Hz),
3.12 (4 H, t, J ) 8.0 Hz), 1.55 (4 H, sextet, J ) 7.6 Hz), 1.10
(6 H, t, J ) 7.3 Hz); 13C (67.9 MHz) δ 193.8, 146.0, 143.0, 136.9,
135.9, 135.4, 134.7, 129.1, 124.5, 123.5, 28.3, 24.4, 14.6; MS
m/z 366 (M+), 351, 337.
Condensation between 13 and benzyne,10 generated in
situ from anthranilic acid, eventually led to the diketone
37 and subsequently the diol 38 as a mixture of the trans
and cis isomers (isomer ratio ) 3:1) (Scheme 6). Treat-
ment of 38 with 2 equiv of thionyl chloride produced the
[2 + 2] cycloaddition adduct 39 as a mixture of the trans
and cis isomers (trans/cis ) 3:1). In addition, the alcohol
40 as a mixture of the trans and cis isomers (isomer ratio
) 2:1) and the ketone 41 were also isolated. The structure
of the trans isomer of 39 was established by X-ray
structure analysis. Unlike the cases of 16 and 32, the
formation of 40 and 41 indicated that the intramolecular
Diol 16. To a solution of 0.18 g (0.89 mmol) of 1-(2-
ethynylphenyl)-2-phenylethyne6 in 10 mL of diethyl ether
under a nitrogen atmosphere at 0 °C was added 0.31 mL of a
2.5 M solution of n-butyllithium (0.78 mmol) in hexanes. The
reaction mixture was then allowed to warm to rt. After 30 min
at rt, a solution of 0.099 g (0.271 mmol) of 15 in 40 mL of
diethyl ether was introduced via cannula. After an additional
12 h, 5 mL of water was introduced, and the reaction mixture
was extracted with diethyl ether. The combined organic
extracts were washed with brine and water, dried over sodium
sulfate, and concentrated. Flash column chromatography
(silica gel/30% diethyl ether in hexanes) provided 0.197 g of
16 (0.256 mmol, 94%, a mixture of the trans and cis isomers,
(11) Zhang, H.-R. Ph.D. Thesis, Department of Chemistry, West
Virginia University, May 2000.
(10) Mallakpour, S. E. Indian J . Chem. 1997, 36B, 354-356.
J . Org. Chem, Vol. 68, No. 15, 2003 5835

Yang et al.
SCHEME 5
SCHEME 6
isomer ratio ) 2:1) as a soil-colored solid: mp 107-113 °C; IR
3528, 3426, 2215, 753 cm-1; 1H (270 MHz) δ 8.24 (2 H, d, J )
7.9 Hz), 7.85 (2 H, d, J ) 7.4 Hz), 7.51-7.4 (6 H, m), 7.4-7.09
(16 H, m), 3.32-3.13 (2 H, m), 3.13-2.98 (2 H, m), 2.48 (2 H,
br), 1.92-1.76 (2 H, m), 1.76-1.52 (2 H, m), 1.03 (6 H, t, J )
7.2 Hz); 13C (67.9 MHz) δ 148.6, 146.9, 140.9, 138.5, 132.7,
131.9, 131.8, 131.7, 129.2, 128.4, 128.1, 127.8, 125.9, 124.9,
124.5, 123.1, 93.3, 93.2, 87.9, 82.0, 75.5, 31.1, 25.0, 15.2; MS
m/z 770 (M+), 753, 736; HRMS calcd for C58H42O2 770.3185,
found 770.3160.
Hz), 7.70-7.26 (16 H, m), 7.21 (2 H, td, J ) 7.3, 1.0 Hz), 7.12
(2 H, td, J ) 7.7, 1.2 Hz), 5.96 (2 H, d, J ) 7.7 Hz), 3.55 (2 H,
br), 2.64 (2 H, m), 1.25 (4 H, m), 0.49 (6 H, t, J ) 6.8 Hz); 13
C
(67.9 MHz) δ 193.7, 149.3, 144.2, 143.7, 141.5, 141.2, 140.7,
138.6, 138.3, 137.6, 136.9, 135.6, 134.1, 130.2, 129.4, 129.1,
128.94, 128.87, 128.7, 128.2, 127.0, 126.7, 123.7, 123.5, 35.1,
25.1, 14.3; MS m/z 769 (MH+), 768; HRMS calcd for C58H40O2
768.3028, found 768.3021. Recrystallization of 17 from
CH2Cl2/2-propanol produced a crystal suitable for X-ray struc-
ture analysis. Compound 18: IR 1447, 753, 691 cm-1; 1H (270
MHz) δ 8.73 (1 H, d, J ) 7.2 Hz), 8.40 (1 H, d, J ) 6.9 Hz),
8.29 (1 H, d, J ) 7.4 Hz), 7.85 (1 H, d, J ) 7.2 Hz), 7.67-7.16
(19 H, m), 7.01 (1 H, t, J ) 7.5 Hz), 6.86 (1 H, t, J ) 7.7 Hz),
5.48 (1 H, d, J ) 7.7 Hz), 2.32-2.22 (1 H, m), 2.2-2.0 (1 H,
m), 1.8-1.4 (4 H, m), 1.12-0.96 (1 H, m), 0.9-0.8 (1 H, m),
0.69 (3 H, t, J ) 7.3 Hz), 0.46 (3 H, t, J ) 7.1 Hz); MS m/z
790, 771 (M+ - Cl), 728. Compound 19: mp 275-277 °C; IR
Com p ou n d s 17-20. To a flask containing 0.05 mL (0.7
mmol) of thionyl chloride in 10 mL of diethyl ether under a
nitrogen atmosphere at 0 °C was added 0.08 mL (1.0 mmol)
of pyridine in 5 mL of diethyl ether via cannula. After 10 min,
0.094 g (0.122 mmol) of 16 in 20 mL of diethyl ether was
introduced slowly via cannula. After 5 h at 0 °C, the reaction
mixture was allowed to warm to rt. After an additional 2 h at
rt, 10 mL of water was introduced, and the organic layer was
separated. The aqueous layer was back extracted with meth-
ylene chloride. The combined organic layers were washed with
water, dried over sodium sulfate, and concentrated. Flash
column chromatography (silica gel/50% methylene chloride in
hexanes) provided 0.008 g of 17 (0.010 mmol, 8%) as a pink
solid, 0.0030 g of 18 (0.0037 mmol, 3%) as a dark solid, 0.026
g of 19 (0.035 mmol, 28%) as a dark brown solid, and 0.029 g
of 20 (0.036 mmol, 30%, trans/cis ) 5:1) as an orange solid.
1
(KBr) 2211, 1695, 761 cm-1; H (270 MHz) δ 9.44 (1 H, dd, J
) 6.9, 1.7 Hz), 8.64 (1 H, dd, J ) 6.9, 1.5 Hz), 8.38 (1 H, d, J
) 7.7 Hz), 7.78 (1 H, d, J ) 7.4 Hz), 7.68 (1 H, d, J ) 7.2 Hz),
7.64-7.31 (16 H, m), 7.26 (1 H, td, J ) 7.5, 1.0 Hz), 7.17 (1 H,
td, J ) 7.4, 0.7 Hz), 7.03 (1 H, td, J ) 7.7, 1.2 Hz), 6.96 (1 H,
td, J ) 7.4, 0.7 Hz), 5.20 (1 H, d, J ) 7.7 Hz), 2.71 (2 H, m),
2.12 (2 H, m), 1.02 (4 H, sextet, J ) 7.9 Hz), 0.68 (6 H, t, J )
7.3 Hz); 13C (67.9 MHz) δ 193.8, 153.3, 145.3, 145.0, 144.4,
144.3, 141.2, 140.0, 139.4, 137.2, 137.0, 136.5, 136.3, 135.2,
134.2, 132.4, 132.0, 131.8, 131.6, 130.7, 130.1, 129.1, 128.94,
128.87, 128.6, 128.5, 128.4, 128.2, 128.1, 127.7, 126.9, 126.1,
1
Compound 17: mp 266-269 °C; IR 1701, 749 cm-1; H (270
MHz) δ 9.35 (2 H, dd, J ) 7.9, 1.2 Hz), 7.93 (2 H, d, J ) 7.2
5836 J . Org. Chem., Vol. 68, No. 15, 2003

Cascade Radical Cyclizations of Benzannulated Enyne-Allenes
125.8, 125.3, 125.0, 124.3, 123.7, 123.6, 123.1, 120.5, 118.5,
102.6, 93.7, 89.0, 88.4, 51.6, 42.5, 18.5, 14.1; MS m/z 753
(MH+), 752, 709; HRMS calcd for C58H40O 752.3079, found
752.3048. Recrystallization of 19 from CH2Cl2/2-propanol
produced a crystal suitable for X-ray structure analysis.
Ack n ow led gm en t. The financial support of the
National Science Foundation (CHE-9618676) and the
Petroleum Research Fund, administered by the Ameri-
can Chemical Society, to K.K.W. is gratefully acknowl-
edged. J .L.P. acknowledges the support (CHE-9120098)
provided by the Chemical Instrumentation Program of
the National Science Foundation for the acquisition of
a Siemens P4 X-ray diffractometer in the Department
of Chemistry at West Virginia University.
Compound 20: mp >340 °C; IR 1640, 1424, 1196, 753 cm-1
;
1H (270 MHz) δ (trans isomer) 8.67 (2 H, d, J ) 7.7 Hz), 7.87
(2 H, t, J ) 7.4 Hz), 7.56-7.20 (22 H, m), 2.54 (2 H, m), 2.42
(2 H, m), 1.27 (2 H, m), 1.03 (2 H, m), 0.44 (6 H, t, J ) 7.2 Hz);
13C (67.9 MHz) δ (trans isomer) 152.4, 148.8, 148.1, 145.7,
144.0, 141.1, 140.4, 139.3, 134.9, 131.9, 130.2, 129.3, 129.0,
128.5, 128.2, 127.8, 127.3, 125.0, 124.5, 123.7, 123.2, 120.0,
111.5, 65.6, 30.2, 25.2, 14.5; 13C (67.9 MHz) δ (cis isomer,
partial) 151.9, 149.0, 145.9, 144.01, 140.97, 139.2, 135.0, 132.1,
130.0, 129.4, 128.8, 127.6, 120.1, 112.0, 65.55, 14.54; MS m/z
807 (MH+), 763, 720; HRMS calcd for C58H41Cl2 807.2585,
found 807.2569. Recrystallization of 20 from CH2Cl2/2-propanol
produced a crystal of the trans isomer suitable for X-ray
structure analysis.
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures and spectroscopic data for 29-35 and 37-41; 1H and/
or 13C NMR spectra for 14-20, 29-35, and 37-41; and
ORTEP drawings and tables of crystallographic data for the
X-ray diffraction analyses of 17, 19, 20, 35, and 39. This
material is available free of charge via the Internet at
http://pubs.acs.org.
J O030147J
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