Palladium(0)-Catalyzed Reactions of Allylic Benzotriazoles with Enamines: A Novel Method for the Stereoselective Synthesis of (4E)-γ,δ-Unsaturated Ketones

Full text of DOI:10.1021/jo9901788

J . Org. Chem. 1999, 64, 7625-7627
7625
Notes
Sch em e 1
P a lla d iu m (0)-Ca ta lyzed Rea ction s of Allylic
Ben zotr ia zoles w ith En a m in es: A Novel
Meth od for th e Ster eoselective Syn th esis of
(4E)-γ,δ-Un sa tu r a ted Keton es
Alan R. Katritzky,* Zhizhen Huang, and Yunfeng Fang
Center for Heterocyclic Compounds, Department of
Chemistry, University of Florida, Gainesville, Florida
32611-7200
etates also react with silylated carbon nucleophiles to give
γ,δ-unsaturated ketones in moderate to good yields.10a,b
Received February 1, 1999
Palladium(0)-catalyzed nucleophilic substitution of al-
lylic compounds is an important methodology in contem-
porary organic synthesis for the preparation of many
classes of compounds.11a-c This method has also been
used to prepare γ,δ-unsaturated ketones by forming the
C(b)-C(c) bond (Scheme 1). Thus, under the catalysis of
Pd(OAc)2/PPh3, piperidinocyclohexene reacts with allylic
phenoxide to form 2-allylcyclohexanone, a γ,δ-unsatur-
ated ketone, in moderate yield.12 Palladium graphite can
also be employed as a heterogeneous catalyst in the above
reaction.13 Utilizing Pd(PPh3)4 catalysis, allyl acetate or
phenoxide reacts with various hexanone enamines to give
2-allylcyclohexanone in moderate yields.14 Under neutral
conditions, ketones and aldehydes react with 2-allyl-
isourea in the presence of a catalytic amount of a
palladium(0) complex to give γ,δ-unsaturated ketones
and aldehydes.15
In recent years, benzotriazole has been widely used as
a synthetic auxiliary.16 Structurally diversified N-allyl-
benzotriazoles have been prepared very conveniently
from allylbenzotriazole.17 In a previous paper, we re-
ported that, under the catalysis of palladium complex,
N-allylbenzotriazoles can react readily with amines as a
nitrogen nucleophile to give a wide range of allylamines
in good yields.18 Enamines are well-known carbon
In tr od u ction
γ,δ-Unsaturated ketones are common moieties in natu-
ral products.1a-c Possible synthetic approaches include
those which form (i) the C(a)-C(b) bond (cf. Scheme 1)
either by the reaction of allyl iodide and tosylmethyl
isocyanide followed by hydrolysis2 or by reacting S phenyl
thioesters or Weinreb-type amides with homoallyl Grig-
nard reagents,3a,b (ii) the C(c)-C(d) bond by conjugate
addition of either lithium vinylcuprate or alkenyl-9-BBN
to R,â-unsaturated carbonyl compounds,4a,b or (iii) the
C(d)-C(e) bond by either the reaction of γ-keto aldehydes
with Wittig reagents5a,b or anionic oxy-Claisen rearrange-
ment of enolates of R-allyloxy ketones.6 However, most
common preparations of γ,δ-unsaturated ketones are by
the formation of the C(b)-C(c) bond (Scheme 1). Such
reactions usually involve a nucleophile of type 2 and an
electrophile of type 3 as also shown in Scheme 1. Thus,
Saucy et al. report that the reaction of isopropenyl ether
(cf. 2, X ) OEt) with tertiary vinyl carbinols (cf. 3, X )
OH) under acid catalysis gives a mixture of (4E)- and
(4Z)-γ,δ-unsaturated ketones in good yields.7 Mukaiyama
et al. prepare γ,δ-unsaturated ketones by reactions of
secondary and tertiary allyl methyl ethers (cf. 3, Y )
OMe) with silyl enol ethers (cf. 2, X ) OSiR3) in the
presence of a catalytic amount of trityl perchlorate.8
Under Lewis acid catalysis, silyl enol ethers react with
some allylic halides or acetates to afford good yields of
γ,δ-unsaturated ketones.9 (R-Sulfenylmethyl)allyl ac-
(10) (a) Kudo, K.; Saigo, K.; Hashimoto, Y.; Houchigai, H.; Hase-
gawa, M. Tetrahedron Lett. 1991, 32, 4311. (b) Kudo, K.; Hashimoto,
Y.; Houchigai, H.; Hasegawa, M.; Saigo, K. Bull. Chem. Soc. J pn. 1993,
66, 848.
(11) (a) Trost, B. M.; Verhoeven, T. R. In Comprehensive Organo-
metallic Chemistry; Wilkinson, S. G., Stone, F. G. A., Abel, E. W., Eds.;
Pergamon Press: New York, 1982; Vol. 8, p 799. (b) Godleski, S. A. In
Comprehensive Organic Synthesis; Trost, B. M., Ed.; Pergamon Press:
Oxford, 1991; Vol. 4, p 585. (c) Katritzky, A. R.; Rachwal, S.; Hitching,
G. J . Tetrahedron 1991, 47, 2683.
(1) (a) Masso, T.; Portella, A.; Rus, E. Perfum. Flavor. 1990, 15, 42.
(b) Atta-ur-Rahman. In Natural Product Chemistry; Atta-ur-Rahman,
Ed.; Springer-Verlag: Berlin, 1986; p 330. (c) Schmidt, R. R. Ibid.; p
383.
(2) Rao, A. V. R.; Deshpande, V. H.; Reddy, S. P. Synth. Commun.
1984, 14, 469.
(3) (a) Fiandanese, V.; Marchese, G.; Naso, F. Tetrahedron Lett.
1988, 29, 3587. (b) Dinh, T. Q.; Armstrong, R. W. Tetrahedron Lett.
1996, 37, 1161.
(4) (a) Naf, F.; Degen, P. Helv. Chim. Acta 1971, 54, 1939. (b) J acob,
P.; Brown, H. C. J . Am. Chem. Soc. 1976, 98, 7832.
(5) (a) Kim, T. H.; Isoe, S. Chem. Commun. 1983, 730. (b) Nishiyama,
T.; Woodhall, J . F.; Lawson, E. N.; Kitching, W. J . Org. Chem. 1989,
54, 2183.
(12) Onoue, H.; Moritani, I.; Murahashi, S. I. Tetrahedron Lett. 1973,
121.
(13) Boldrini, G. P.; Savoia, D.; Tagliavini, E.; Trombini, C.; Ronchi,
A. U. J . Organomet. Chem. 1984, 268, 97.
(14) Hirio, K.; Suya, K.; Sato, S.; Yamamoto, M. Annu. Rep. Tohoku
Coll. Pharm. 1985, 32, 75.
(15) Inoue, Y.; Toyofuku, M.; Taguchi, M.; Okada, S.; Hashimoto,
H. Bull. Chem. Soc. J pn. 1986, 59, 885.
(16) Katritzky, A. R.; Lan, X.; Yang, J . Z.; Denisko, O. V. Chem.
Rev. 1998, 98, 409.
(6) Koreeda, M.; Luengo, J . I. J . Am Chem. Soc. 1985, 107, 5572.
(7) Saucy, G.; Marbet, R. Helv. Chim. Acta 1967, 50, 2091.
(8) Mukaiyama, T.; Nagaoka, H.; Ohshima, M.; Murakami, M.
Chem. Lett. 1986, 1009.
(9) Reetz, M. T.; Walz, P.; Hu¨bner, F.; Hu¨ttenhain, S. H.; Heimbach,
H.; Schwellnus, K. Chem. Ber. 1984, 117, 322.
(17) (a) Katritzky, A. R.; Xie, L.; Toader, D.; Serdyuk, L. J . Am.
Chem. Soc. 1995, 117, 12015. (b) Katritzky, A. R.; Li, J .; Malhotra, N.
Liebigs Ann. Chem. 1992, 843. (c) White, W. A.; Weingarten, H. J . Org.
Chem. 1967, 32, 213. (d) Stork, G.; Brizzolara, A.; Landesman, H.;
Szmuszkovicz, J .; Terrell, R. J . Am. Chem. Soc. 1963, 85, 207.
(18) Katritzky, A. R.; Yao, J .; Qi, M. J . Org. Chem. 1998, 63, 5232.
10.1021/jo9901788 CCC: $18.00 © 1999 American Chemical Society
Published on Web 09/10/1999

7626 J . Org. Chem., Vol. 64, No. 20, 1999
Notes
Ta ble 1. Ster eoselective Syn th esis of (4E)-γ,δ-Un sa tu r a ted Keton es by P a lla d iu m -Ca ta lyzed Rea ction
starting
benzotriazole
product
compd
no.
R1
R2
R5
R6
E/Za
96/4
5
5
5
8a
8b
8c
-(CH2)4-
CH3CH2
Ph
CH3
CH3
98/2 (98/2)
95/5
10a
10a
10b
10b
10b
11
12
12
14a
14b
14c
14d
14e
14f
14g
14h
-(CH2)4-
(CH3)2CHCH2CH2
(CH3)2CHCH2CH2
1-NpthCH2
1-NpthCH2
1-NpthCH2
H
H
H
H
H
99/1
90/10 (94/6)
97/3
96/4
95/5
90/10
99/1
98/2
CH3CH2
CH3CH2
Ph
CH3
CH3
CH3
-(CH2)4-
CH3CH2
-(CH2)4-
CH3
CH3
CH3
(CH3)2CHCH2CH2
(CH3)2CHCH2CH2
(CH3)2CHCH2CH2
(CH3)2CHCH2CH2
(CH3)2CHCH2CH2
Ph
a
The E/Z ratios were determined by GC/MS on a Hewlett-Packard 5890 Series II Gas Chromatograph HP-5 (30 m × 0.32 mm × 0.25
µm) capillary column with the temperature range from 100 to 150 °C at the rate 10 °C/min. The E/Z ratio in parentheses are taken from
the reaction using toluene as solvent.
Sch em e 2
Sch em e 3
nucleophiles in organic synthesis.19 In this paper, we
demonstrate that various allylic benzotriazoles react with
enamines under palladium catalysis in the presence of
stoichiometric zinc bromide to provide a general method
for the synthesis of γ,δ-unsaturated ketones.
act as the nucleophile to form a C-C bond by reaction
with N-cinnamylbenzotriazole 5. Qualitatively, the reac-
tion rates are in the order 6a > 6b > 6c for the three
enamines.
Resu lts a n d Discu ssion
In the presence of Pd(OAc)2/PPh3 alone, 1-(γ-phenyla-
llyl)benzotriazole 5 and enamine 6a did not react in
refluxing benzene. The departure of a benzotriazole anion
as a leaving group is well-known to be facilitated in the
presence of the Lewis acid ZnBr2.20a-c Indeed, under the
co-action of Pd(OAc)2/PPh3 and ZnBr2, 1-(E)-phenylallyl-
benzotriazole 5 reacts smoothly with enamines 6a -c to
form iminium salts 7a -c, which undergo subsequent
hydrolysis to produce the expected γ,δ-unsaturated ke-
tones 8a -c in good yields (81-91%) (Scheme 2). Com-
pound 8a is a known compound synthesized via a stannyl
enolate in 93% yield by Yasuda et al.21 The (E)-configura-
tions of products 8a -c were determined by the vicinal
coupling constants of the δ-proton signal of 16 Hz.
Efficient reaction of 5 with enamine 6a requires an excess
of 6a together with a catalytic amount of Pd(OAc)2/PPh3
and 2 equiv of ZnBr2 (the reaction was much slower with
1.2 equiv of ZnBr2). Enamine 6a derived from a cyclic,
6b from an acyclic, and 6c from an aryl ketone can each
R-Allylbenzotriazole (9) was lithiated by n-BuLi and
treated subsequently with an alkyl halide to give regi-
oselectively the R-monosubstituted allylbenzotriazoles
10a ,b in yields of 90-92% as previously reported.17b
R-Allylbenzotriazole 9 can also be used in a double-
lithiation technique with considerable flexibility: it was
sequentially twice lithiated, and two of the same or
different alkyl groups were introduced to give the R,R-
disubstituted allylbenzotriazoles 11 and 12 (Scheme 3).
Catalysis by Pd(OAc)2/PPh3 and ZnBr2 transforms
R-substituted allylbenzotriazoles 10a , 10b, 11, and 12
into cationic π-allylpalladium complex intermediates 13
(Scheme 3). The enamine 6 then attacks the γ-position
of R-substituted allylbenzotriazoles 10a , 10b, 11, and 12
which are sterically less hindered. No product from attack
at the R-position of compounds 10a , 10b, 11, and 12 was
found. Both the monosubstituted 10a ,b and the disub-
stituted allylbenzotriazoles 11 and 12 produced the
expected (E)-γ,δ-unsaturated ketones 14a -h in yields of
80-90% after hydrolysis (Table 1). The (E)-configurations
of products 14a -h were demonstrated by the value of
their vicinal coupling constants shown by the δ-proton
signal to be 15.0-15.5 Hz.
(19) Cook, A. G., Ed. Enamines: Synthesis, Structure and Reactions;
Marcel Dekker: New York, 1988.
(20) (a) Katritzky, A. R.; Wu, H.; Xie, L.; Rachwal, S.; Rachwal, B.;
J iang, J .; Zhang, G.; Lang, H. Synthesis 1995, 1315. (b) Katritzky, A.
R.; Chen, J .; Belyakov, S. A. Tetrahedron Lett. 1996, 37, 6631. (c)
Katritzky, A. R.; Wang, X.; Xie, L.; Toader, D. J . Org. Chem. 1998, 63,
3445.
The ratios of (E)-isomer to (Z)-isomer of 8a -c and
14a -h were obtained by GC/MS, in which there were
two peaks possessing the same molecular weight. The
(21) Yasuda, M.; Hayashi, K.; Katoh, Y.; Shibata, I.; Baba, A. J . Am.
Chem. Soc. 1998, 120, 715.

Notes
J . Org. Chem., Vol. 64, No. 20, 1999 7627
1.28-1.45 (m, 1H), 1.45-1.60 (m, 1H), 1.60-1.80 (m, 2H), 1.80-
2.20 (m, 6H), 2.20-2.50 (m, 4H), 5.30-5.50 (m, 2H); 13C NMR δ
22.5, 24.8, 27.5, 27.9, 30.4, 32.5, 33.2, 38.7, 42.0, 50.8, 127.2,
132.6, 212.9. Anal. Calcd for C14H24O: C, 80.71; H, 11.61.
Found: C, 80.50; H, 11.51.
analysis results show that this reaction has high stereo-
selectivities of (E)-γ,δ-unsaturated ketones ((E)-isomers
>90%).
Con clu sion
(E)-4,10-Dim eth yl-6-u n d ecen -3-on e (14b): oil; yield 83%;
1
(yield was 90% when toluene was used as solvent); H NMR δ
The structurally diversified allylic benzotriazoles 5,
10a , 10b, 11, and 12 react with various enamines
smoothly under the action of Pd(OAc)2/PPh3 and ZnBr2,
affording a general method for the stereoselective syn-
thesis of (4E)-γ,δ-unsaturated ketones 8a -c and 14a -
h . Compared with previous methods, our method has the
advantages of readily available starting materials, con-
venient manipulations, mild reaction conditions, high
regio- and stereoselectivity, and good yields.
0.86 (d, J ) 6.6 Hz, 6H), 1.00-1.18 (m, 6H), 1.18-1.30 (m, 2H),
1.48-1.55 (m, 1H), 1.90-2.10 (m, 3H), 2.25-2.40 (m, 1H), 2.40-
2.68 (m, 3H), 5.30 (dt, J ) 15.3, 6.4 Hz, 1H), 5.42 (dt, J ) 15.1,
6.4 Hz, 1H); 13C NMR δ 7.6, 16.0, 22.4, 27.4, 30.3, 34.5, 36.2,
38.6, 46.2, 126.6, 133.1, 214.7. Anal. Calcd for C13H24O: C, 79.53;
H, 12.32. Found: C, 79.30; H, 12.81.
(E)-4-Meth yl-8-(1-n a p h th yl)-6-octen -3-on e (14c): oil; yield
82%; 1H NMR δ 0.90-1.04 (m, 6H), 1.90-2.10 (m, 1H), 2.17-
2.37 (m, 3H), 2.38-2.50 (m, 1H), 3.69 (d, J ) 5.7 Hz, 2H), 5.41
(dt, J ) 15.3, 7.0 Hz, 1H), 5.74 (dt, J ) 15.3, 6.3 Hz, 1H), 7.22-
7.50 (m, 4H), 7.65 (d, J ) 7.5 Hz, 1H), 7.77 (d, J ) 6.9 Hz, 1H),
7.93 (d, J ) 7.2 Hz, 1H); 13C NMR δ 7.4, 16.0, 34.3, 35.8, 35.9,
45.7, 123.8, 125.3, 125.4, 125.5, 125.9, 126.7, 128.4, 128.8, 130.6,
131.7, 133.6, 136.4, 214.3. Anal. Calcd for C19H22O: C, 85.67;
H, 8.33. Found: C, 85.58; H, 8.53.
(E)-2-Meth yl-6-(n a p h th yl)-1-p h en yl-4-h exen -1-on e (14d ):
oil; yield 82%; 1H NMR δ 1.16 (d, J ) 6.7 Hz, 3H), 2.11-2.25
(m, 1H), 2.45-2.60 (m, 1H), 3.41-3.58 (m, 1H), 3.74 (d, J ) 5.8
Hz, 2H), 5.48 (dt, J ) 15.3, 6.9 Hz, 1H), 5.75 (dt, J ) 15.2, 6.1
Hz, 1H), 7.25 (d, J ) 7.2 Hz, 1H), 7.30-7.49 (m, 5H), 7.50-7.60
(m, 1H), 7.70 (d, J ) 7.9 Hz, 1H), 7.80-8.02 (m, 4H); 13C NMR
δ 17.0, 36.0, 36.5, 40.7, 124.0, 125.4, 125.5, 125.7, 126.0, 126.8,
128.1, 128.2, 128.6, 128.9, 130.9, 131.9, 132.8, 133.7, 136.5, 136.6,
203.8. Anal. Calcd for C23H22O: C, 87.85; H, 7.07. Found: C,
87.87; H, 7.23.
2-[(E )-3-(1-Na p h t h a le n yl)-2-p r op e n yl]cycloh e xa n on e
(14e): mp 63.5-64.5 °C; Yield 86%; 1H NMR δ 1.25-1.50 (m,
1H), 1.50-1.75 (m, 2H), 1.77-1.90 (m, 1H), 1.90-2.20 (m, 3H),
2.20-2.60 (m, 4H), 3.76 (d, J ) 6.2 Hz, 2H), 5.50 (dt, J ) 15.3,
7.0 Hz, 1H), 5.72 (dt, J ) 15.3, 6.3 Hz, 1H), 7.30-7.60 (m, 4H),
7.70 (d, J ) 8.0 Hz, 1H), 7.83 (d, J ) 6.6 Hz, 1H), 8.01 (d, J )
8.8 Hz, 1H); 13C NMR δ 24.7, 27.8, 32.4, 33.2, 36.1, 41.9, 50.4,
124.0, 125.3, 125.5, 125.6, 125.9, 126.7, 128.5, 129.5, 130.2, 131.8,
133.7, 136.7, 212.5. Anal. Calcd for C20H22O: C, 86.28; H, 7.97.
Found: C, 86.24; H, 7.97.
(E)-4,7,10-Tr im et h yl-6-u n d ecen e-3-on e (14f): oil; yield
80%; 1H NMR δ 0.79-0.98 (m, 6H), 0.99-1.18 (m, 6H), 1.18-
1.37 (m, 2H), 1.40-1.58 (m, 1H), 1.59 (s, 3H), 1.92-2.04 (m, 2H),
2.04-2.18 (m, 1H), 2.23-2.40 (m, 1H), 2.41-2.52 (m, 2H), 2.53-
2.64 (m, 1H), 5.04 (t, J ) 7.2 Hz, 1H); 13C NMR δ 7.5, 16.0, 22.4,
27.5, 29.6, 31.4, 34.4, 37.2, 37.4, 46.2, 120.9, 137.5, 214.7; HRMS
(CI) m/z calcd for C14H26O 210.1984, found 210.2056.
2-(3-I s o p e n t y l-6-m e t h y l-2-h e p t e n y l)c y c lo h e x a n o n e
(14g): oil; yield 87%; 1H NMR δ 0.84-0.97 (m, 12H), 1.18-1.37
(m, 5H), 1.43-1.60 (m, 2H), 1.60-1.68 (m, 2H), 1.80-1.90 (m,
1H), 1.90-2.06 (m, 6H), 2.07-2.20 (m, 1H), 2.20-2.35 (m, 2H),
2.35-2.50 (m, 2H), 5.04 (t, J ) 6.8 Hz, 1H); 13C NMR δ 22.5,
24.9, 27.2, 27.3, 27.7, 27.9, 28.2, 33.3, 34.8, 37.5, 37.6, 41.9, 51.2,
121.3, 141.7, 212.8; HRMS (CI) m/z calcd for C19H34O 278.2610,
found 278.2610.
5-Isop en t yl-2,8-d im et h yl-p h en yl-4-n on en -1-on e (14h ):
oil; yield 84%; 1H NMR δ 0.83-1.02 (m, 12H), 1.15-1.35 (m,
7H), 1.40-1.60 (m, 2H), 1.90-2.10 (m, 4H), 2.10-2.30 (m, 1H),
2.40-2.55 (m, 1H), 3.40-3.60 (m, 1H), 5.08 (t, J ) 7.0 Hz, 1H),
7.43-7.60 (m, 3H), 7.96 (d, J ) 7.4 Hz, 2H); 13C NMR δ 16.8,
22.5, 27.7, 28.0, 28.3, 31.8, 34.7, 37.4, 37.7, 41.2, 120.9, 128.2,
128.5, 132.7, 136.6, 142.4, 204.1. Anal. Calcd for C22H34O: C,
84.02; H, 10.90. Found: C, 83.87; H, 10.51.
Exp er im en ta l Section
Gen er a l Com m en ts. Melting points were determined on a
hot stage apparatus without correction. 1H NMR (300 MHz) and
13C NMR (75 MHz) spectra were recorded in CDCl3 with TMS
and CDCl3, respectively, as the internal reference. Compounds
5, 10a , 10b, 11, and 12 and enamines 6a -c were prepared by
the literature method.17a-d
Gen er a l P r oced u r e for th e Syn th esis of (4E)-γ,δ-Un sa t-
u r a ted Keton es 8a -c a n d 14a -i. Under argon, a mixture of
allylbenzotriazole 5, 10a , 10b, 11, or 12 (2 mmol), Pd(OAc)2 (13
mg, 0.06 mmol), PPh3 (63 mg, 0.24 mmol), and ZnBr2 (0.90 g, 4
mmol) was refluxed in benzene (10 mL) (toluene also was used
as solvent in some cases; the reaction temperature was 80-90
°C) for 15 min. Then the solution of enamine 6 (4 mmol) in
benzene (5 mL) (or toluene when toluene was used as solvent)
was added, and the reaction mixture was refluxed for 1-3 h.
After the evaporation of benzene, water (10 mL) was added and
the mixture was refluxed for 30 min. NaOH (1 N, 30 mL) was
added, and the mixture was extracted with Et2O (3 × 30 mL).
The organic phase was washed with a saturated solution of
ammonium chloride (10 mL) and dried over magnesium sulfate.
After removal of solvent, the residue was subjected to column
chromatography to produce (4E)-γ,δ-unsaturated ketones 8a -c
and 14a -h .
2-[(E)-3-P h en yl-2-p r op en yl]cycloh exa n on e (8a ): oil; yield
91%; 1H NMR δ 1.32-1.52 (m, 1H), 1.60-1.78 (m, 2H), 1.79-
1.96 (m, 1H), 1.97-2.25 (m, 3H), 2.27-2.56 (m, 3H), 2.60-2.81
(m, 1H), 6.14-6.30 (m, 1H), 6.68 (d, J ) 16.0 Hz, 1H), 7.14-
7.62 (m, 5H); 13C NMR δ 25.0, 27.9, 32.9, 33.5, 42.0, 50.6, 125.9,
126.9, 128.3, 128.4, 131.5, 137.5, 212.4. Anal. Calcd for
C
15H18O: C, 84.06; H, 8.48. Found: C, 83.63; H, 8.25.
(E)-4-Meth yl-7-p h en yl-6-h ep ten -3-on e (8b): oil; Yield 90%
1
(yield was 87% when toluene was used as solvent); H NMR δ
1.03 (t, J ) 7.3 Hz, 3H), 1.11 (d, J ) 6.9 Hz, 3H), 2.17-2.31 (m,
1H), 2.37-2.59 (m, 3H), 2.60-2.72 (m, 1H), 6.05-6.19 (m, 1H),
6.38 (d, J ) 15.7 Hz, 1H), 7.13-7.37 (m, 5H); 13C NMR δ 7.6,
16.2, 34.4, 36.3, 45.9, 125.9, 127.0, 127.4, 128.4, 131.8, 137.2,
214.2. Anal. Calcd for C14H18O: C, 83.12; H, 8.97. Found: C,
82.91; H, 9.06.
(E)-2-Meth yl-1,5-d ip h en yl-4-p en ten -1-on e (8c): oil; yield
81%; 1H NMR δ 1.18-1.38 (m, 3H), 2.28-2.45 (m, 1H), 2.65-
2.80 (m, 1H), 3.52-3.70 (m, 1H), 6.12-6.30 (m, 1H), 6.41 (d, J
) 14.3 Hz, 1H), 7.12-7.40 (m, 5H), 7.40-7.60 (m, 3H), 7.95 (t,
J ) 3.9 Hz, 2H); 13C NMR δ 17.2, 36.8, 40.9, 126.0, 127.0, 127.5,
128.2, 128.4, 128.6, 132.0, 132.9, 136.4, 137.3, 203.5. Anal. Calcd
for C18H18O: C, 86.36; H, 7.25. Found: C, 86.18; H, 7.24.
2-[(E)-6-Meth yl-2-h ep ten yl]cycloh exa n on e (14a ): oil; yield
90%; 1H NMR δ 0.87 (d, J ) 6.0 Hz, 6H), 1.18-1.28 (m, 2H),
J O9901788