Regiospesific Synthesis of Polysubstituted Phenols via the Palladium-Catalyzed Enyne-Diyne [4 + 2] Cross-Benzannulation Pathway

Article abstract of DOI:10.1021/jo971817m

An efficient method for the synthesis of polysubstituted phenols via the consecutive palladium-catalyzed enyne-diyne [4 + 2] cross-benzannulation reaction and subsequent deprotection step was developed. In all cases, the reactions proceeded in a regiospecific manner affording the corresponding polysubstituted phenols in good overall yields. It was shown that a more useful one-pot methodology could be applied to the synthesis of polysubstituted phenols 4a-e. The synthetically useful p-methoxyphenylacetylene 13 and its monosilylated derivative 12 were smoothly prepared via exhaustive or partial desilylation of bis-silylated aromatic adduct 8c, respectively.

Full text of DOI:10.1021/jo971817m

1244
J . Org. Chem. 1998, 63, 1244-1247
Regiosp esific Syn th esis of P olysu bstitu ted P h en ols via th e
P a lla d iu m -Ca ta lyzed En yn e-Diyn e [4 + 2] Cr oss-Ben za n n u la tion
P a th w a y
Vladimir Gevorgyan, Long Guo Quan, and Yoshinori Yamamoto*
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, J apan
Received October 2, 1997
An efficient method for the synthesis of polysubstituted phenols via the consecutive palladium-
catalyzed enyne-diyne [4 + 2] cross-benzannulation reaction and subsequent deprotection step
was developed. In all cases, the reactions proceeded in a regiospecific manner affording the
corresponding polysubstituted phenols in good overall yields. It was shown that a more useful
one-pot methodology could be applied to the synthesis of polysubstituted phenols 4a -e. The
synthetically useful p-methoxyphenylacetylene 13 and its monosilylated derivative 12 were smoothly
prepared via exhaustive or partial desilylation of bis-silylated aromatic adduct 8c, respectively.
Phenol derivatives are omnipresent structural con-
benzannulation pathway. We have recently reported an
efficient approach to polysubstituted benzenes via the
novel palladium-catalyzed homodimerization of conju-
gated enynes3 and the enyne-diyne cross-benzannula-
tion4 reactions (eq 3).5 This methodology allowed us to
stituents in pharmacologically important molecules, and
consequently, much attention has been focused on their
syntheses. Most of the methods for preparation of
substituted phenols involve various kinds of modification
of aromatic precursors (eq 1).1 Furthermore, a number
of reports on the synthesis of phenols via construction of
the benzene skeleton from different acyclic units have
appeared in the literature during the past three decades.
Among them, perhaps two the following reactions could
be considered as the most general and synthetically
important procedures: ring closure of dienylketenes and
cycloaddition of Fisher carbenes with alkynes (eq 2).2
construct a benzene ring with several alkyl, aryl, or silyl
substituents in a regio- and in some cases4b chemospecific
manner. Encouraged by successful benzannulation of
carbon- and silyl-substituted enynes and diynes, we
intended to apply this technique to the synthesis of
synthetically useful heteroatom-substituted aromatics,
particularly phenol and its derivatives. Herein we wish
to report a novel efficient method for the synthesis of
polysubstituted phenols via the palladium-catalyzed
enyne-yne [4 + 2] cycloaddition protocol (eq 4).
To the best of our knowledge, there is no precedent for
the preparation of phenol derivatives through a [4 + 2]
(1) For a general review, see: (a) Whiting, D. A. In Comprehensive
Organic Chemistry; Stoddart, J . F., Ed.; Pergamon Press: Oxford, 1979;
Vol. 1, Chapter 4.2. For a review on aryl C-O bond-forming reactions,
see: (b) Chiu, C. K.-F. In Comprehensive Organic Functional Group
Transformations; Katritzky, A. R., Meth-Cohn, O., Rees, C. W., Eds.;
Pergamon Press: New York, 1995; Vol. 2, Chapter 2.13. For a review
on electrophilic hydroxylation, see: (c) J acquesy, J . C.; Gesson, J . P.;
J onannetand, M. P. Rev. Chem. Intermed. 1988, 9, 1-26, 5. For a
review on OH- and OR- as nucleophiles in aromatic substitution, see:
(d) The Chemistry of the Hydroxyl Group; Patai, S.; Ed.; Wiley
Interscience: New York, 1971; Vol. 1; p 83. For most recent works on
the preparation of phenols from aryl halides and aryl ethers, see: (e)
Mann, G.; Hartwig, J . F. J . Org. Chem. 1997, 62, 5413. (f) Pews, R.
G.; Lysenko, Z.; Vosejpka, P. C. J . Org. Chem. 1997, 62, 8255. (g)
Nayak, M. K.; Chakraborti, A. K. Tetrahedron Lett. 1997, 38, 8749.
(2) For reviews, see: (a) Wulff, W. D. In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: New York,
1991; Vol. 5, 1065. (b) Schore, N. E. Chem. Rev. (Washington, D.C.)
1988, 88, 1081-1119. See also: (c) Merlic, C. A.; Xu, D. J . Am. Chem.
Soc. 1991, 113, 7418. (d) Turnbull, P.; Heilman, M. J .; Moore, H. W.
J . Org. Chem. 1996, 61, 2584. (e) Koo, S. H.; Liebeskind, L. S. J . Am.
Chem. Soc. 1995, 117, 3389. (f) Covarrubias-Zu´n˜iga, A.; R´ıos-Barrios,
E. J . Org. Chem. 1997, 62, 5688. (g) Collomb, D.; Doutheau, A.
Tetrahedron Lett. 1997, 1397. (h) Barluenga, J .; Refna´ndez-Acebes, A.;
Trabanco, A. A.; Flo´rez, J . J . Am. Chem. Soc. 1997, 119, 7591.
Resu lts a n d Discu ssion
Syn th esis of P olysu bstitu ted P h en ols. The obvi-
ous impossibility of introduction of unprotected hydroxy
group into either of the partners (enynes or diynes) of
the [4 + 2] cycloaddition reaction prompted us to search
for more suitable precursors for phenol synthesis, bearing
a hydroxy group equivalent. After some work on the
design of reactants,8 we found that readily available and
(3) Saito, S.; Salter, M. M.; Gevorgyan, V.; Tsuboya, N.; Tando, K.;
Yamamoto, Y. J . Am. Chem. Soc. 1996, 118, 3970.
(4) (a) Gevorgyan, V.; Takeda, A.; Yamamoto, Y. J . Am. Chem. Soc.
1997, 119, 11313. (b) Gevorgyan, V.; Sadayori, N.; Yamamoto, Y.
Tetrahedron Lett. 1997, 38, 8603.
(5) Some data on related processes such as thermal6,7 or Lewis acid
mediated6 intramolecular enyne-yne [4 + 2] cycloaddition reactions
were recently reported.
S0022-3263(97)01817-3 CCC: $15.00 © 1998 American Chemical Society
Published on Web 01/30/1998

Synthesis of Polysubstituted Phenols
Ta ble 1. Syn th esis of P h en ols via th e
J . Org. Chem., Vol. 63, No. 4, 1998 1245
Section). Thus, 2,4-disubstituted enynes 1a ,b in the
presence of Pd(PPh3)4 (2 mol %) and (o-Tol)3P (20 mol
%)10 in THF smoothly reacted with diynes 2, producing
siloxybenzenes 3a -d in 61-83% isolated yields (method
A, entries 1, 2, 3, and 5, Table 1). Trisubstituted E-enyne
1c (with a methyl group cis-oriented toward an alkynyl
moiety) easily reacted with diyne 2b, affording penta-
substituted aromatic silyl ether 4e in 66% isolated yield
(entry 7), whereas its Z counterpart 1d did not undergo
the benzannulation reaction at all (entry 8, Table 1).12
Subsequent deprotection of 3 with TBAF afforded the
desired phenols 4 in good overall yields (eq 5, Table 1).
Practically, the simpler and more convenient one-pot
procedure B gave phenols 4c,d in even slightly higher
isolated yields, as compared to the overall yields obtained
via method A (entries 4 and 6 vs entries 3 and 5
correspondingly, Table 1). It was found that in all cases
the enyne-diyne [4 + 2] cycloaddition reaction proceeded
not only in regiospecific but also in chemospecific fashion,
affording tetra- and pentasubstituted cross-benzannula-
tion products 3, exclusively.13 No detectable amounts of
enyne dimer13 or any other regioisomers of 3 were
P a lla d iu m -Ca ta lyzed En yn e-Diyn e Ben za n n u la tion
P r otocol
1
detected by H NMR and GC-MS analyses of the crude
reaction mixtures.
Syn th esis of Alk oxyben zen es. We next attempted
to apply the palladium-catalyzed enyne-diyne benzan-
nulation method for the synthesis of polysubstituted
benzenes bearing an alkoxy group.14,15 At first, we tried
to introduce an alkoxy group in the diyne component.
However, the mono- and dialkoxy-substituted diynes
2e,f9 appeared to be unstable under the various reaction
conditions tested, and in all cases only the rapid total
decomposition of the diynes was observed. The introduc-
tion of a methoxy susbstituent at the terminal olefinic
moiety of enyne turned out to be unsuccessful, as well.
Thus, mono- and dimethoxy-substituted enynes 5 and 6
did not undergo the [4 + 2] benzannulation reaction with
a
The benzannulation reactions were carried out in the Wheaton
microreactors with 0.5 mmol of 1 and 2 in THF (1 mL) at 100 °C
in the presence of Pd(PPh3)4 (2 mol %) and (o-Tol)3P (20 mol %)
except where otherwise noted. Isolated yield. c All deprotection
b
reactions of 3 were conducted with TBAF (2 equiv) in THF (1 mL)
at room temperature. The reaction was carried ut in the presence
of Pd(PPh3)4 (5 mol %).
d
(8) The bis-silylated enyne 1e did not undergo the benzannulation
reaction. Moreover, all attempts to carry out selective deprotection of
the alkynyl-TMS group of 1e failed, perhaps due to similar reactivity
of both silyl groups toward nucleophilic reagents (e.g., MeO- and F-).9
Furthermore, we did not succeed in isolating the siloxy-substituted
enyne 1f and diyne 2d due to their low stability.
easily handled 2-siloxy-substituted enyne 1 could per-
fectly serve for this purpose (eq 5, Table 1). Two methods
(9) Brandsma, L. Preparative Acetylenic Chemistry, 2nd ed.; Elsevier:
Amsterdam, 1988.
(10) In the absence of additional phosphine ligand all benzannula-
tion reactions (even in the presence of 5 mol % of Pd(PPh3)4) proceeded
somewhat slower than in the presence of 2 mol % of Pd(PPh3)4-20
mol % of (o-Tol)3P catalyst system.11
(11) Gevorgyan, V.; Tando, K.; Uchiyama, N.; Yamamoto, Y. Un-
published results.
(12) During our study on the benzannulation of carba-substituted
enynes we found that enynes having a methyl group trans-oriented
toward the alkynyl moiety reacted much slower than the corresponding
cis-isomers.4b
(13) We have recently shown that some of palladium-catalyzed cross-
benzannulation reactions between diynes and monosubstituted enynes
were not completely chemoselective,4a accordingly, trace to notable
amounts of [4 + 2] enyne-enyne homodimer3 together with major
cross-benzannulation product were produced. For some examples on
chemospecific benzannulation of the alkyl- and aryl-substituted enynes,
see ref 4b.
(14) Alkoxy-substituted aromatics are ubiquitous structural units
in biologically important molecules and thus are of great importance
for synthetic organic chemistry. See, for example, ref 1b.
(15) Recently, Merlic and co-worker have demonstrated an example
of the construction of alkoxybenzene derivative via ruthenium-
catalyzed intramolecular cyclization of dienylalkynes; see: Merlic, C.
A.; Pauly, M. E. J . Am. Chem. Soc. 1996, 118, 11319.
were utilized for the preparation of phenols 4: the
stepwise method A and one-pot method B. According to
method A the aromatic silyl ethers 3 were isolated and
then converted into the phenols 4 by treatment with Bu4-
NF, whereas in method B the benzannulation reaction
and the deprotection step 3 f 4 were accomplished in
one-pot sequence (for details, see the Experimental
(6) Danheiser, R. L.; Gould, A. E.; Fernandez de la Predilla, R.;
Helgason, A. L. J . Org. Chem. 1994, 59, 5514.
(7) Burrell, R. C.; Daoust, K. J .; Bradley, A. Z.; DiRico, K. J .;
J ohnson, R. P. J . Am. Chem. Soc. 1996, 118, 4218.

1246 J . Org. Chem., Vol. 63, No. 4, 1998
Gevorgyan et al.
diynes 2a ,b. In contrast, the introduction of a methoxy
group into the internal olefinic position of enyne was
much more fruitful. Thus, 2-methoxy-1-buten-3-yne (7)
in the presence of Pd(PPh3)4 (5 mol %) smoothly reacted
with diyne 2, producing methoxybenzene 8 in reasonable
to good chemical yields (eq 6). The reaction of 7 with
via the partial desilylation into the monosilylated ben-
zene 12 or via the exhaustive desilylation into the
p-methoxyethynylbenzene (13) (eq 9).
Con clu sion
A synthetically useful and effective method for the
preparation of polysubstituted siloxybenzenes (3), alkoxy-
benzenes (8), and phenols (4, 11) via the palladium-
catalyzed enyne-diyne [4 + 2] cross-benzannulation
reaction was developed. It was shown that conjugated
enynes bearing a hydroxy group equivalent at internal
olefinic moiety, in contrast to enynes bearing ones at any
other positions, or correspondingly substituted diynes,
are the best substrates for the preparation of phenols and
aryl ethers. The efficient conversion of bis-silyl substi-
tuted methoxybenzene 8c into the corresponding pheny-
lacetylenes 12 and 13 was demonstrated.
diphenyldiyne 2b was chemospecific, affording the cross-
benzannulation product 8 exclusively. Unlike benzannu-
lation of 2b, the reactions of dodecadiyne 2a and bis-silyl-
diyne 2c with 7 were less chemoselective.13 In later cases,
the enyne homodimer 93 was detected by 1H NMR
analyses of the crude reaction mixtures in 18 and 36%
yields, respectively, together with the major cross-ben-
zannulation products 8a ,c (eq 6). The test experiments
indicated that, in the absence of diyne 2, the methoxy-
substituted enyne 7 smoothly underwent the [4 + 2]
homodimerization reaction (eq 7).3
Exp er im en ta l Section
Gen er a l In for m a tion . All solvents were purified and
dried before use according to standard procedures. Reactions
were performed under an argon atmosphere in oven-dried
glassware. The diynes 2a -c were purchased from Aldrich.
Silylated enynes 1a -d were obtained from the corresponding
alkynyl ketones via the standard procedures for the prepara-
tion of silyl ethers.17 All other starting materials were
prepared according to the described methods.9
Syn th esis of P h en ols 4a -e. Gen er a l P r oced u r e. Step -
w ise Meth od A. Diyne 2 (1.0 mmol) and enyne 1 (1.0 mmol)
were consecutively added at room temperature to a solution
of Pd(PPh3)4 (2 mol %) and (o-Tol)3P (20 mol %) in THF (1.0
mL) in a 5 mL Wheaton microreactor under an argon atmo-
sphere. After being stirred for 12 h at 100 °C, THF was
evaporated off, hexane was added, and the resulting mixture
was filtered through silica gel. Purification by silica gel
column chromatography using hexanes-ethyl acetate as an
eluent gave siloxybenzenes 3 in 61-83% yields. TBAF (1 M
solution in THF, 1 mmol) was added at room temperature to
a solution of 3 (0.5 mmol) in THF (2.5 mL). After being stirred
for 1 h, THF was evaporated off and the mixture was extracted
with ether-water. Purification by column chromatography
(silica gel, hexanes-ethyl acetate as an eluent) gave phenols
4 in 77-94% yields.
1
Though the dimer 9 was detected by GLC and H NMR
analyses of the crude reaction mixtures, its enol ether
moiety was not hydrolytically stable under the conditions
of column chromatography, and p-methoxyacetophenone
(10) was isolated in 52% overall yield (eq 7).
Although the alkoxy-substituted aromatics by them-
selves are synthetically useful compounds,14 they could
be also easily transformed into the corresponding phenols
using standard deprotection techniques. As an example,
16
the treatment of methoxybenzenes 8a and 8b with BBr3
afforded the phenols 11a and 11b in 75 and 81% isolated
yields, respectively (eq 8).9 Furthermore, the bis-silyl
substituted benzene 8c could be effectively transformed
On e-P ot Meth od B. After completion of the first benzan-
nulation step, which was carried out as described in method
(16) Felix, A. M. J . Org. Chem. 1974, 39, 1427.
(17) For a review, see: Brownbridge, P. Synthesis 1983, 1.

Synthesis of Polysubstituted Phenols
J . Org. Chem., Vol. 63, No. 4, 1998 1247
A, TBAF (1M solution in THF, 1 mmol) was directly added to
the reaction mixture at room temperature, and the mixture
was stirred for 1 h at room temperature. The workup similar
to that for the second step of method A gave the phenols 4c,d
in 73 and 57% overall yields, respectively.
3a : 1H NMR (CDCl3, 270 MHz) δ 6.49 (s, 2H), 2.73-2.66
(m, 4H), 2.47 (t, J ) 6.6 Hz, 2H), 1.61-1.31(m, 16H), 0.97-
0.86 (m, 18H), 0.18 (s, 6H); 13C NMR (67.8 MHz, CDCl3) δ
154.5, 146.5, 146.4, 117.8, 115.9, 95.9, 77.7, 35.1, 34.7, 32.7,
31.8, 31.2, 30.5, 29.3, 25.7, 22.6, 22.0, 19.3, 18.2, 14.1, 13.9,
13.6, -4.3; IR (neat) 2956, 2929, 2858, 1599, 1466, 1308,
0.1253, 1157, 862, 839, 665 cm-1; MS (EI) m/z 428 (M+, 100);
HRMS calcd for C28H48OSi 428.3474, found 428.3473. Anal.
Calcd for C28H48OSi: C, 78,43; H, 11.28. Found: C, 78.34; H,
11.07.
3b: 1H NMR (CDCl3, 270 MHz) δ 7.65-7.26 (m, 10H), 6.74
(d, J ) 2.7 Hz, 1H), 6.72 (d, J ) 2.7 Hz, 1H), 2.88 (t, J ) 7.7
Hz, 2H), 1.76-1.32 (m, 8H), 1.01 (s, 9H), 0.89 (t, J ) 7.0 Hz,
3H), 0.24 (s, 6H); 13C NMR (67.8 MHz, CDCl3) δ 155.4, 147.5,
146.1, 141.1, 130.9, 129.5, 128.2, 127.7, 127.5, 127.3, 124.2,
119.5, 118.8, 114.2, 94.9, 88.2, 35.4, 31.8, 30.6, 29.3, 25.7, 22.7,
18.3, 14.1, -4.3; IR (neat) 2954, 2927, 2858, 1593, 1492, 1460,
1441, 1340, 1194, 854, 754 cm-1; MS (E1) m/z 468 (M+ 100);
HRMS calcd for C32H40OSi 468.2849, found 468.2851. Anal.
Calcd for C32H40OSi: C, 81.99; H, 8.60. Found: C, 82.10; H,
8.74.
22.6, 21.8, 19.2, 14.0, 13.6; IR (neat) 3270, 2956, 2929, 2871,
2860, 1456, 1317, 1174, 771, 665 cm-1; MS (E1) m/z 306 (M+
100); HRMS calcd for C22H26O 306.1984; found 306.1983.
4d : 1H NMR (CDCl3, 270 MHz) δ 7.68-6.95 (m, 15H), 6.88
(s, 2H), 5.20 (s, 1H); 13C NMR (75.45 MHz, CDCl3) δ 155.1,
146.8, 140.7, 130.7, 129.5, 128.0, 127.8, 127.6, 127.5, 123.8,
115.6, 113.1, 94.2, 88.9; IR (KBr) 3340, 1597, 1560, 1490, 1421,
1182, 771, 692 cm-1; MS (E1) m/z 346 (M+ 100); HRMS calcd
for C26H18O 346.1358, found 346.1365.
4e: 1H NMR (CDCl3, 300 MHz) δ 7.54-7.30 (m, 5H), 6.61
(s, 1H), 4.78 (s, 1H), 2.90 (t, J ) 7.1 Hz, 2H), 2.27 (t, J ) 6.8
Hz, 2H), 2.23 (s, 3H), 1.58-1.22 (m, 8H), 0.97 (t, J ) 6.8 Hz,
3H), 0.85 (t, J ) 7.53 Hz, 3H); 13C NMR (75.45 MHz, CDCl3)
δ 152.8, 145.8, 142.9, 141.2, 129.3, 127.5, 126.9, 121.0, 114.4,
113.6, 94.5, 78.2, 32.0, 31.8, 30.7, 23.2, 21.8, 19.2, 14.0, 13.6,
11.5; IR (KBr) 3468, 2958, 2931, 2872, 2858, 1593, 1475, 1407,
1251, 702 cm-1; MS (E1) m/z 320 (M+ 100); HRMS calcd for
C
23H28O 320.2140, found 320.2146. Anal. Calcd for C23H28O:
C, 86.20; H, 8.81. Found: C, 85.82; H, 8.72.
8a : 1H NMR (CDCl3, 300 MHz) δ 7.28 (d, J ) 9.0 Hz, 1H),
6.70 (d, J ) 2.58 Hz, 1H), 6.64 (dd, J ) 9.0,2.58 Hz, 1H), 3.78
(s, 3H), 2.72 (t, J ) 7.77 Hz, 2H), 2.43 (t, J ) 6.75 Hz, 2H),
1.65-1.32 (m, 8H), 0.97-0.91 (m, 6H); 13C NMR (67.8 MHz,
CDCl3) δ 158.8, 146.4, 133.2, 115.8, 114.3, 110.9, 91.9, 79.1,
55.1, 34.6, 32.8, 31.1, 22.6, 22.0, 19.2, 14.0, 13.6; IR (neat) 2956,
1604, 1494, 1465, 1298, 1161, 1039, 808 cm-1; MS (E1) m/z
244 (M+ 100); HRMS calcd for C17H24O 244.1827, found
3c: 1H NMR (CDCl3, 270 MHz) δ 7.56-7.25 (m, 5H), 6.66
(s, 2H), 2.74 (t, J ) 7.7 Hz, 2H), 2.88 (t, J ) 6.9 Hz, 2H), 1.69-
1.32 (m, 8H), 1.04-0.93 (m, 12H), 0.86 (t, J ) 7.2 Hz, 3H), 0.2
(s, 6H); 13C NMR (67.8 MHz, CDCl3) δ 154.5, 147.2, 145.6,
141.4, 129.4, 127.6, 127.0, 119.3, 118.7, 115.0, 95.7, 78.3, 34.9,
32.7, 30.7, 25.7, 22.6, 21.8, 19.3, 18.3, 14.0, 13.6, -4.3; IR (neat)
3033, 2956, 2929, 1595, 1462, 1340, 1255, 1197, 1182, 875, 835,
244.1830. Anal. Calcd for
Found: C, 83.26; H, 9.88.
C17H24O: C, 83.55; H, 9.90.
8b: 1H NMR (CDCl3, 270 MHz) δ 7.69-7.65, 7.49-7.23 (m,
10H), 7.58 (d, J ) 8.5 Hz, 1H), 6.96 (d, J ) 2.6 Hz, 1H), 6.89
(dd, J ) 8.5, 2.6 Hz1H), 3.86 (s, 3H); 13C NMR (67.8 MHz,
CDCl3) δ 159.6, 145.5, 140.5, 134.2, 131.0, 129.2, 128.1, 127.8,
127.6, 127.5, 123.7, 114.9, 113.9, 112.9, 90.8, 89.4, 55.3; IR
(KBr) 3059, 2964, 2837, 1606, 1595, 1554, 1491, 1479, 1415,
1299, 1213, 1176, 1029, 891, 760, 698 cm-1. Anal. Calcd for
698 cm-1; MS (E1) m/z 420 (M+ 100); HRMS calcd for C28H40
-
OSi 420.2849, found 420.2856. Anal. Calcd for C28H40OSi: C,
79.94; H, 9.58. Found: C, 79.63; H, 9.80.
C
21H16O: C, 88.70; H, 5.67. Found: C, 88.36; H, 5.82. Anal.
3d : 1H NMR (CDCl3, 270 MHz) δ 7.68-6.96 (m, 15H), 6.90
(s, 2H), 1.01 (s, 9H), 0.26 (s, 6H); 13C NMR (67.8 MHz, CDCl3)
δ 155.4, 146.5, 140.9, 130.7, 129.6, 128.0, 127.7, 127.4, 123.9,
120.2, 120.1, 113.4, 94.3, 89.1, 25.7, 18.3, -4.2; IR (KBr) 2954,
2929, 2854, 1591, 1494, 1425, 1209, 954, 854, 781, 702, 688
cm-1; MS (E1) m/z 460 (M+ 100); HRMS calcd for C32H32OSi
460.2223; found 460.2223. Anal. Calcd for C32H32OSi: C,
83.43; H, 7.00. Found: C, 83.52; H, 7.09.
Calcd for C21H16O: C, 88.70; H, 5.67. Found: C, 88.36; H, 5.82.
8c: 1H NMR (CDCl3, 270 MHz) δ 7.45 (d, J ) 8.5 Hz, 1H),
7.01 (d, J ) 2.6 Hz, 1H), 6.80 (dd, J ) 8.5, 2.6 Hz, 1H), 3.79
(s, 3H), 0.38 (s, 9H), 0.24 (s, 9H); 13C NMR (67.8 MHz, CDCl3)
δ 158.9, 144.7, 134.6, 120.2, 113.4, 106.9, 95.3, 55.2, 0.0, -1.0;
IR (neat) 2956, 2150, 1589, 1556, 1477, 1463, 1286, 1182, 1139,
893, 840 cm-1; MS (E1) m/z 276 (M+ 100); HRMS calcd for
C
C
15H24OSi2 276.141 06, found 276.1375. Anal. Calcd for
15H24OSi2: C, 65.15; H, 8.74. Found: C, 65.29; H, 8.54.
11a : 1H NMR (CDCl3, 270 MHz) δ 7.24 (d, J ) 8.1 Hz, 1H),
3e: 1H NMR (CDCl3, 270 MHz) δ 7.59-7.31 (m, 5H), 6.66
(s, 3H), 2.91 (t, J ) 7.8 Hz, 2H), 2.3 (t, J ) 6.8 Hz, 2H), 2.33
(s, 3H), 1.54-0.99 (m, 20H), 0.88 (t, J ) 6.6 Hz, 3H), 0.24 (s,
6H); 13C NMR (67.8 MHz, CDCl3) δ 152.9, 145.6, 142.4, 141.6,
129.4, 127.5, 126.7, 125.9, 117.2, 115.0, 94.8, 79.0, 32.3, 31.8,
30.8, 25.8, 23.3, 21.9, 19.3, 18.3, 14.1, 13.6, 12.6, -4.01; IR
(neat) 2956, 2929, 2858, 1587, 1463, 1400, 1338, 1259, 1168,
6.64 (d, J ) 2.7 Hz, 1H), 6.57 (dd, J ) 8.1, 2.7 Hz, 1H), 4.83
(s, 1H), 2.70 (t, J ) 7.5 Hz, 2H), 1.65-1.36 (m, 8H), 0.97-0.91
(m, 6H); 13C NMR (67.8 MHz, CDCl3) δ 155.8, 146.7, 133.4,
115.9, 115.5, 112.6, 92.0, 78.9, 34.4, 32.6, 31.1, 22.6, 22.0, 19.2,
14.0, 13.7; IR (neat) 3370, 2956, 2929, 2860, 1654, 1606, 1577,
1286, 1230 cm-1; MS (EI) m/z 230 (M+, 100); HRMS calcd for
1082, 837, 698 cm-1
H, 9.74. Found C, 80.44; H, 9.79. Anal. Calcd for C29H42
OSi: C, 80.12; H, 9.74. Found: C, 80.44; H, 9.79.
. Anal. Calcd for C29H42OSi: C, 80.12;
-
C
16H22O 230.1670, found 230.1675.
11b: 1H NMR (CDCl3, 270 MHz) δ 7.55-7.24 (m, 11H), 6.89
4a : 1H NMR (CDCl3, 270 MHz) δ 6.49 (s, 2H), 4.78 (s, 1H),
2.78-2.66 (m, 4H), 2.46 (t, J ) 6.7 Hz, 2H), 1.65-1.30 (m,
16H), 0.97-0.87 (m, 9H); 13C NMR (67.8 MHz, CDCl3) δ 154.3,
147.1, 115.5, 112.9, 95.9, 35.0, 34.7, 32.7, 31.7, 31.2, 30.5, 29.3,
22.6, 22.0, 19.3, 14.1, 14.0, 13.6; IR (neat) 3350, 2956, 2927,
2858, 1106, 1458, 1147, 665 cm-1; MS (E1) m/z 314 (M+ 100);
HRMS calcd for C22H34O 314.2609, found 314.2607.
(d, J ) 2.6 Hz, 1H), 6.80 (dd, J ) 8.4, 2.6 Hz, 1H), 5.12 (s,
1H); 13C NMR (67.8 MHz, CDCl3) δ 155.6, 145.7, 140.1, 134.5,
131.1, 129.2, 128.2, 127.9, 127.7, 127.6, 116.4, 114.4, 114.2,
90.8, 89.3; IR (neat) 3388, 1604, 1595, 1492, 1197, 1114, 908,
732 cm-1; MS (EI) m/z 270 (M+, 100); HRMS calcd for C20H14
O
270.1044, found 270.1056.
12: 1H NMR (CDCl3,300 MHz) δ 7.47 (d, J ) 8.4 Hz, 1H),
7.01 (d, J ) 2.8 Hz, 1H), 6.81 (dd, J ) 8.4, 2.8 Hz, 1H), 3.82
(s, 3H), 3.13 (s, 1H), 0.37 (s, 9H); 13C NMR (67.8 MHz, CDCl3)
δ 159.0, 144.8, 134.9, 120.1, 119.2, 113.4, 85.1, 78.7, 55.2, -1.1;
IR (neat) 3309, 2956, 2100, 1589, 1463, 1288, 1234, 1037, 883,
4b: 1H NMR (CDCl3, 270 MHz) δ 7.56-7.40 (m, 10H), 6.73
(s, 2H), 5.11 (s, 1H), 2.89 (t, J ) 6.75 Hz, 2H), 1.79-1.22 (m,
8H), 0.88 (t, J ) 6.75 Hz, 3H); 13C NMR (67.8 MHz, CDCl3) δ
155.2, 148.0, 146.4, 140.8, 130.9, 129.4, 128.2, 127.7, 127.6,
127.5, 124.1, 114.8, 114.1, 113.9, 94.8, 87.9, 35.4, 31.8, 30.6,
29.4, 22.7, 14.1; IR (neat) 3369, 2954, 2927, 2856, 1595, 1493,
1454, 754, 665 cm-1; MS (E1) m/z 354 (M+ 100); HRMS calcd
839 cm-1; MS (E1) m/z 204 (M+ 100); HRMS calcd for C12H16
-
OSi 204.0971, found 204.0983.
C
26H26O 354.1984, found 354.1989.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
all new compounds (16 pages). This material is contained in
libraries on microfiche, immediately follows this article in the
microfilm version of the journal, and can be ordered from the
ACS; see any current masthead page for ordering information.
4c: 1H NMR (CDCl3, 270 MHz) δ 7.57-7.32 (m, 5H), 6.67
(d, J ) 2.5 Hz, 1H), 6.64 (d, J ) 2.5 Hz, 1H), 4.68 (s, 1H), 2.78
(t, J ) 7.75 Hz, 2H), 2.28 (t, J ) 6.75 Hz, 3H); 1.70-1.25 (m,
8H), 0.95 (t, J ) 7.25 Hz, 3H), 0.85 (t, J ) 7.25 Hz, 3H); 13C
NMR (67.8 MHz, CDCl3) δ 154.3, 147.6, 145.9, 141.1, 129.3,
127.5, 127.1, 114.6, 114.5, 113.9, 95.6, 78.0, 34.9, 32.6, 30.6,
J O971817M