Novel syntheses of 1,2-diarylprop-2-en-1-ones

Full text of DOI:10.1021/jo981725c

J . Org. Chem. 1998, 63, 9983-9986
9983
Notes
Sch em e 1
Novel Syn th eses of
1,2-Dia r ylp r op -2-en -1-on es
Alan R. Katritzky,* Dorin Toader,‡ and
Christophe Chassaing
Center for Heterocyclic Compounds,
Department of Chemistry, University of Florida,
Gainesville, Florida 32611-7200
Received August 24, 1998
In tr od u ction
1,2-Diarylprop-2-en-1-ones have found wide use in the
synthesis of a variety of heterocyclic substrates, many
of which show biological activity. The epoxides derived
from 1,2-diarylpropenones show herbicidal activity;1 1,4-
addition of nucleophiles produces fungicidal 1,2-diaryl-
propanones,2 which also display central nervous system
activity.3 Nazarov cyclization of such propenones leads
to indanones.4 Pyrazolinecarboxamides5 as well as other
pyrazolines,6 both classes used as insecticides, can be
made via 1,2-diarylpropenones. 2,3-Diaryl-1-pyrroline
1-oxides are synthesized from 1,2-diarylpropenones.7
The direct insertion of an R-methylene group into
ketones is the most often encountered approach to 1,2-
diarylpropenones. Piperidine in the presence of formal-
dehyde,8 N-methylaniline trifluoroacetate9 in the pres-
ence of trioxane, and N,N,N′,N′-tetramethylmethane-
diamine10 all produce 1,2-diarylpropenones starting from
the corresponding deoxybenzoins.
diarylpropanone. These substrates are synthesized by one
of the following approaches: (i) insertion of chlorometh-
ylcarbene into the C-H bond of deoxybenzoins;11 (ii)
conjugate addition of anions of protected cyanohydrins
to â-nitrostyrenes followed by hydrolysis;12 (iii) tin(II)
induced R-bromomethylation of silyl enol ethers;13 (iv)
addition of methoxymethyl methyl sulfate to diaryl-
alkynes;14 (v) reduction of enamino ketones obtained from
deoxybenzoins and N,N-dimethylformamide dimethylace-
tal;15 (vi) a Pre´vost reaction performed upon 1,1-diaryl-
allyl alcohols.16
Organometallic reagents have been used for the syn-
thesis of 1,2-diarylpropenones: (i) Watanabe’s coupling
of aroyl chlorides with phenylketene in the presence of
Pd(0) catalyst;17 (ii) ruthenium-catalyzed alkylidene cou-
pling of R-diazo ketones.18 Several miscellaneous methods
have been used to produce 1,2-diarylpropenones: (i) from
aryllead tricarboxylates;19 (ii) by the reaction of R-aryl-
alkenyl Grignard reagents with nitriles;20 (iii) hyperva-
lent iodine oxidation of allenes.21
The second largest group of methods consists of base-
induced â-eliminations of a 3-heteroatom-substituted 1,2-
‡ Present address: Zeneca Pharmaceuticals, 1800 Concord Pike, PO
Box 15437, Wilmington, DE 19850-5437.
(1) Rempfler, H.; Kunz, W. U.S. Patent 4,894,083, 1990; Chem.
Abstr. 1990, 113, 40432.
(2) Schaller, R.; Mildenberger, H.; Handte, R.; Hartz, P.; Sachse, B.
German Patent 3,527,334, 1987; Chem. Abstr. 1987, 106, 115241.
(3) (a) Moffett, R. B.; Hester, J . B. J . Med. Chem. 1972, 15, 1243.
(b) Takahashi, K.; Shimizu, S.; Ogata, M. Synth. Commun. 1987, 17,
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(4) (a) Suzuki, T.; Ohwada, T.; Shudo, K. J . Am. Chem. Soc. 1997,
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J . Med. Chem. 1978, 21, 437.
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Rowson, G. P. European Patent 227,055, 1987; Chem. Abstr. 1987, 107,
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M.; Udagawa, T. J apanese Patent 62 56,476 [87 56, 476], 1987; Chem.
Abstr. 1988, 108, 75392. (c) J acobson, R. M. European Patent 153,-
127, 1985; Chem. Abstr. 1986, 105, 42787.
In connection with our use of benzotriazole as a
synthetic auxiliary,22 we have recently shown that 1,2-
diarylpropenones can be obtained by fluoride ion vicinal
elimination of silicon in substrates of type 3 (Scheme 1).23
The synthetic value of this synthesis of 4 (Scheme 1)
(11) Makrandi, J . K.; Grover, S. K. Tetrahedron Lett. 1976, 22, 3179.
(12) Ferrin˜o, S. A.; Maldonado, L. A. Synth. Commun. 1980, 10, 717.
(13) Hayashi, M.; Mukaiyama, T. Chem. Lett. 1987, 1283.
(14) Lebedev, M. Yu.; Balenkova, E. S. Zh. Org. Khim. 1991, 27,
1388.
(15) SanMart´ın, R.; Martinez de Marigorta, E.; Dom´ınguez, E.
Tetrahedron 1994, 50, 2255.
(6) (a) Ozawa, K.; Nakajima, Y.; Tsugeno, M.; Ishii, S.; Hatanaka,
M.; Hirose, M.; Kudo, M. European Patent 58,424, 1982; Chem. Abstr.
1983, 98, 16679. (b) Giles, D. P.; Willis, R. J . European Patent 113,-
213, 1984; Chem. Abstr. 1984, 101, 230572. (c) Van Daalen, J . J .;
Mulder, R. German Patent 2,529,689, 1976; Chem. Abstr. 1976, 84,
164772. (d) Grosscurt, A. C.; van Hes, R.; Wellinga, K. J . Agric. Food
Chem. 1979, 27, 406.
(7) Black, D. St. C.; J ohnstone, L. M. Aust. J . Chem. 1984, 37, 95.
(8) Fiesselmann, H.; Ribka, J . Chem. Ber. 1956, 89, 27.
(9) Gras, J .-L. Tetrahedron Lett. 1978, 24, 2111.
(10) (a) deSolms, S. J . J . Org. Chem. 1976, 41, 2650. (b) Ogata, H.;
Matsumoto, H.; Tawara, K.; Ueda, M.; Kimoto, S.; Tsutsumiuchi, M.
J apanese Patent 61 53,239 [86 53, 239], 1986; Chem. Abstr. 1986, 105,
190663.
(16) Ciganek, E.; Calabrese, J . C. J . Org. Chem. 1995, 60, 4439.
(17) (a) Mitsudo, T.-A.; Kadokura, M.; Watanabe, Y. Tetrahedron
Lett. 1985, 26, 5143. (b) Mitsudo, T.-A.; Kadokura, M.; Watanabe, Y.
J . Org. Chem. 1987, 52, 3186.
(18) Akita, M.; Hua, R.; Knox, S. A. R.; Moro-oka, Y.; Nakanishi,
S.; Yates, M. I. Chem. Commun. (Cambridge) 1997, 51.
(19) Kopinski, R. P.; Pinhey, J . T. Aust. J . Chem. 1983, 36, 311.
(20) Dickens, J . P.; McKay, W. R. U. S. Patent 4,628,104, 1986;
Chem. Abstr. 1987, 106, 102288.
(21) Moriarty, R. M.; Hopkins, T. E.; Vaid, R. K.; Vaid, B. K.; Levy,
S. G. Synthesis 1992, 847.
(22) Katritzky, A. R.; Lan, X.; Yang, Z. J .; Denisko, O. V. Chem.
Rev. 1998, 98, 409.
(23) Katritzky, A. R.; Toader, D. J . Am. Chem. Soc. 1997, 119, 9321.
10.1021/jo981725c CCC: $15.00 © 1998 American Chemical Society
Published on Web 11/25/1998

9984 J . Org. Chem., Vol. 63, No. 26, 1998
Ta ble 1. P r ep a r a tion of 2,3-Dia r ylp r op en on es 4
Notes
3, 4
Ar1
Ar2
yield 3 (%)
reacn conditions 3 f 4: acid/solvent/time (h)
yield 4 (%)
a
4-MeC6H4
4-MeOC6H4
93
p-TsOH/MeOH/72
TFA/CH2Cl2/0.3
TFA/CH2Cl2/1
98
99
88
76
94
72
76
82
75
b
c
d
e
f
2-MeC6H4
2-FC6H4
4-FC6H4
2-ClC6H4
2-MeC6H4
4-MeC6H4
4-MeOC6H4
4-FC6H4
4-ClC6H4
72
83
86
98
91
90
88
TFA/CH2Cl2/6
4-MeOC6H4
2-MeC6H4
4-MeC6H4
2-MeC6H4
2,4,6-(Me)3C6H2
TFA/CH2Cl2/1.1
p-TsOH/MeOH/2a
TFA/CH2Cl2/1
TFA/CH2Cl2/1
TFA/CH2Cl2/0.5
g
h
a
The reaction was performed at reflux.
Sch em e 2
was limited by the formation of significant amounts
of chalcone byproducts as a result of an anionic rear-
rangement.23,24 We now show that the vicinal elimina-
tion of silicon in 3 can be accomplished under acidic
conditions making this approach valuable for the syn-
thesis of 4.
Resu lts a n d Discu ssion
Reagents 1a -d were prepared as previously des-
cribed.23 Addition of the carbanions derived from 1 to
acid chlorides afforded adducts 3a -h in excellent yields,
after the elimination of chloride anion, as the tempera-
ture of the reaction mixture rose from -78 °C to room
temperature. The analogous reaction of esters or nitriles
did not afford the desired ketones 3 (Scheme 1). All our
attempts to utilize enolizable acyl halides failed to give
the corresponding ketone probably due to the hardness
of the anion derived from 1. The reaction of the carban-
ions derived from 1 with aroyl chlorides works well
regardless of the electronic character of the reagents 1
or the chlorides 2. Thus, electron-rich 1e, 2f as well as
electron poor 1c, 2d all give excellent yields of the
corresponding 3a -h . Steric effects, which are expected
to play a role in the case of reagents 1a ,f and acid
chlorides 2a ,e, do not influence the outcome of the
reaction. It is worth mentioning that substrates 3a -h
did not undergo nucleophilic addition at the carbonyl
when treated with n-BuLi probably due to the steric
congestion. Ketones 3a -h are all glassy compounds
which tend to retain solvent and are therefore difficult
to obtain in pure state. However, when these compounds
were kept under high vacuum for 1 day, satisfactory
NMR spectra and in some cases combustion analyses
were obtained.
Vicinal elimination of silicon was accomplished by
stirring adduct 3a -h with acid in the appropriate solvent
at room temperature (Scheme 1 and Table 1). The
presence of a catalytic amount of p-toluenesulfonic acid
in methanol promoted the elimination reaction in 3a and
afforded 4 in 98% yield. Under these conditions, the
reaction was slow and complete transformation of 3a
required 72 h. Use of 2 equiv of trifluoroacetic acid (TFA)
in methylene chloride accelerated the reaction, and 4a
was obtained in 99% yield after 0.3 h. The rate of the
transformation 3 f 4 depends on the electronic character
of Ar1. Thus in the presence of TFA, electron-rich 3h
undergoes elimination in 0.5 h while electron deficient
3c necessitates 6 h for the same transformation to be
completed. Steric congestion due to a substituent in the
ortho position of the phenyl group has little effect upon
the elimination conditions as was the case with 3b,f-h .
The extreme case 3e, where both phenyl groups possess
a bulky ortho substituent, was reluctant to undergo
elimination at room temperature in the presence of TFA.
The transformation was accomplished in 72% yield upon
reflux in methanol with catalytic amount of p-toluene-
sulfonic acid. After simple washing with water and
extraction of the byproduct benzotriazole into dilute
aqueous sodium hydroxide, the 1,2-diarylpropenones
4a -h were obtained in high yields.
This new approach to structures of type 4 possesses
significant advantages when compared to the previously
described methods. Thus, a large pool of readily available
starting materials allows for a wide diversity of the two
aryl groups by combining arylmethyl halides, aroyl
chlorides, and (chloromethyl)trimethylsilane (Scheme 2).
To demonstrate this concept, a 9:1 mixture of ((1- and
((2-benzotriazolyl)methylene)arene 6 was prepared in
almost quantitative yield by the displacement of halogen
in 4-chlorobenzyl chloride (5) (Scheme 2). The mixture 6
was deprotonated and reacted with (chloromethyl)tri-
methylsilane at -78 °C, allowed to reach room temper-
ature and cooled to -78 °C, deprotonated, and reacted
with benzoyl chloride. The crude mixture after work up
was subjected to acid hydrolysis with TFA in methylene
chloride to afford 7 in 48% overall yield. Thus, benzo-
triazole acts as an useful auxiliary for building 7 from a
large variety of 2 and 5 without the need for separation
of intermediates.
In summary a new and general method for the syn-
thesis of 1,2-diarylprop-2-en-1-ones has been presented.
This new approach allows for the use of a large pool of
available reagents, utilizes mild reaction conditions, is
insensitive to electronic and steric effects, and proceeds
in high yields.
Exp er im en ta l Section
Gen er a l Meth od s. Melting points were determined with a
(24) Katritzky, A. R.; Voronkov, M.; Toader, D. J . Chem. Soc., Perkin
Trans. 2 1998, in press.
capillary melting point apparatus equipped with
a digital

Notes
J . Org. Chem., Vol. 63, No. 26, 1998 9985
thermometer. H and 13C NMR spectra were collected on a 300
MHz NMR spectrometer (300 and 75 MHz, respectively) using
CDCl3 as solvent. Tetrahydrofuran (THF) was distilled under
nitrogen immediately before use from sodium/benzophenone.
(Chloromethyl)trimethylsilane was purchased from Gelest, Inc.
Column chromatography was conducted with silica gel grade
230-400 mesh. The chromatographic technique was flash chro-
matography as described by Still25 with a 3:1 hexanes/ethyl ether
mixture unless otherwise stated. All organometallic reactions
were carried out under argon in oven-dried glassware. All other
reagents were reagent grade and were used without purification.
Gen er a l P r oced u r e for th e P r ep a r a tion of Com p ou n d s
3a -h . n-BuLi in hexanes (1.43 M, 2.14 mL, 0.003 mol) was
added to the appropriate 1a -e (0.003 mol) dissolved in THF (50
mL), and the mixture was cooled at -78 °C. After 30 min the
appropriate aroyl chloride 2a -f (0.003 mol) was added, and the
reaction mixture was allowed to reach room temperature in 16
h. Aqueous ammonium chloride saturated solution was added
(40 mL), and the mixture was stirred at room temperature for
1 h. The aqueous layer was extracted with ethyl ether (2 × 30
mL), and the combined organic layers were washed with brine
(2 × 30 mL), dried (MgSO4), and had the solvent removed to
give a residue which was subjected to flash column chromatog-
raphy.
20.2, 21.8, 28.0, 80.5, 113.1, 119.8, 123.6, 124.1, 125.8, 125.9,
126.7, 128.7, 128.9, 129.8, 131.1, 133.3, 133.5, 135.6, 136.9, 137.1,
137.7, 146.8, 201.4. HRMS (EI) (m/e): calcd for C26H29N3OSi,
427.2080; found, 427.2094.
2-(1H -1,2,3-Ben zot r ia zol-1-yl)-2-(2-m et h ylp h en yl)-1-(4-
m eth ylp h en yl)-3-(tr im eth ylsilyl)p r op a n -1-on e (3 g): color-
less glass; 1H NMR δ -0.18 (s, 9H), 2.35 (s, 3H), 2.44 (s, 3H),
2.35-2.62 (m overlapped, 2H), 6.51 (d, J ) 7.7 Hz, 1H), 6.72-
6.81 (m, 2H), 7.06-7.10 (m, 2H), 7.18-7.32 (m, 6H), 8.03 (d, J
) 8.2 Hz, 1H); 13C NMR δ -0.1, 20.2, 21.0, 30.7, 78.8, 112.9,
119.8, 123.5, 125.3, 126.6, 128.1, 129.0, 129.8, 130.9, 133.4, 134.5,
136.7, 137.3, 138.5, 146.6, 201.8. HRMS (EI) (m/e) calcd for
C26H29N3OSi, 427.2080; found, 427.2195.
2-(1H-1,2,3-Ben zotr ia zol-1-yl)-2-[4-(m eth yloxy)p h en yl]-
1-(2,4,6-t r im et h ylp h en yl)-3-(t r im et h ylsilyl)p r op a n -1-on e
(3h ): colorless glass; 1H NMR δ -0.04 (s, 9H), 2.11 (s, 6H), 2.22
(s, 3H), 2.75 (d, J ) 14.8 Hz, 1H), 2.85 (d, J ) 14.8 Hz, 1H),
4.05 (s, 3H), 6.63 (br s, 2H), 6.75 (d, J ) 8.5 Hz, 2H), 7.10 (d, J
) 8.2 Hz, 2H), 7.22 (t, J ) 7.7 Hz, 1H), 7.34-7.38 (m, 2H), 8.13
(d, J ) 7.9 Hz, 1H); 13C NMR δ -0.1, 20.3, 20.5, 31.6, 55.2, 80.3,
113.5, 113.8, 119.4, 123.0, 125.7, 127.9, 128.0, 129.2, 133.2, 133.4,
136.5, 138.0, 146.4, 159.6, 207.8. Anal. Calcd for C28H33N3O2Si:
C, 71.30; H, 7.05; N, 8.91; found, C, 71.75; H, 7.06; N, 8.79.
Gen er a l P r oced u r e for th e P r ep a r a tion of Com p ou n d s
4a -h . p-Toluenesulfonic acid monohydrate (0.1 mmol) or tri-
fluoroacetic acid (2 mmol) was added to a solution of 3 (1 mmol)
in methanol (5 mL) or methylene chloride (4 mL), and the
mixture was stirred at room temperature or heated under reflux
for the time indicated in Table 1. In the case of 4a ,e methanol
was removed under reduced pressure, and the residue was
dissolved in methylene chloride (20 mL). In all cases the solution
in methylene chloride was washed with water, extracted with
aqueous sodium hydroxide solution (5%, 2 × 20 mL) and brine
(2 × 20 mL), and then dried (MgSO4). The residue was subjected
to flash chromatography.
1
2-(1H-1,2,3-Ben zotr ia zol-1-yl)-1-[4-(m eth yloxy)p h en yl]-
2-(4-m eth ylp h en yl)-3-(tr im eth ylsilyl)p r op a n -1-on e (3a ): the
physical data for this compound have been previously reported.23
2-(1H -1,2,3-Ben zot r ia zol-1-yl)-1-(4-flu or op h en yl)-2-(2-
m eth ylp h en yl)-3-(tr im eth ylsilyl)p r op a n -1-on e (3b): color-
less glass; 1H NMR δ -0.24 (s, 9H), 2.11 (s, 3H), 2.40-2.45 (m,
2H), 6.89 (t, J ) 8.1 Hz, 2H), 7.02-7.04 (m, 2H), 7.14 (t, J ) 7.4
Hz, 1H), 7.24-7.31 (m, 4H), 7.56 (t, J ) 5.7 Hz, 2H), 8.03 (d, J
) 6.6 Hz, 1H); 13C NMR δ -0.1, 22.0, 27.6, 78.7, 113.0, 115.1 (d,
J ) 21.9 Hz), 120.0, 123.9, 125.5, 127.2, 128.0, 128.7, 132.2 (d,
J ) 8.9 Hz), 133.3, 133.4, 137.3 (d, J ) 38.5 Hz), 146.8, 164.7
(d, J ) 255.4 Hz), 195.0. Anal. Calcd for C25H26FN3OSi: C, 69.57;
H, 6.07; N, 9.74; found, C, 69.32; H, 6.44; N, 10.07.
1-[4-(Met h yloxy)p h en yl]-2-(4-m et h ylp h en yl)p r op -2-en -
1-on e (4a ): the physical data for this compound have been
previously reported.23
2-(1H -1,2,3-Ben zot r ia zol-1-yl)-1-(4-ch lor op h en yl)-2-(2-
flu or op h en yl)-3-(tr im eth ylsilyl)p r op a n -1-on e (3c): colorless
glass; H NMR δ -0.19 (s, 9H), 2.44 (d, J ) 14.7 Hz, 1H), 2.55
1-(4-F lu or op h en yl)-2-(2-m et h ylp h en yl)p r op -2-en -1-on e
1
(4b): colorless oil; H NMR δ 2.19 (s, 3H), 5.98 (s, 1H), 5.99 (s,
1
1H), 7.07-7.18 (m, 3H), 7.20-7.28 (m, 3H), 7.89-7.93 (m, 2H);
13C NMR δ 20.3, 115.3 (d, J ) 21.9 Hz), 126.0, 127.4, 128.3,
129.6, 130.2, 132.2 (d, J ) 9.2 Hz), 133.3 (d, J ) 3.0 Hz), 135.4,
138.1, 149.0, 165.3 (d, J ) 254.3 Hz), 194.6. Anal. Calcd for
C16H13FO: C, 79.98; H, 5.45. Found: C, 79.58; H, 5.64.
1-(4-Ch lor op h en yl)-2-(2-flu or op h en yl)p r op -2-en -1-on e
(4c): colorless oil; 1H NMR δ 5.89 (s, 1H), 6.14 (s, 1H), 7.04 (t, J
) 8.5 Hz, 1H), 7.18 (t, J ) 7.4 Hz, 1H), 7.30-7.43 (m, 4H), 7.83
(d, J ) 8.4 Hz, 2H); 13C NMR δ 115.7 (d, J ) 21.6 Hz), 124.4 (d,
J ) 3.5 Hz), 126.0, 128.6, 130.0 (d, J ) 3.3 Hz), 130.4 (d, J )
8.3 Hz), 135.1, 139.2, 143.3, 159.4 (d, J ) 247.3 Hz), 194.6. Anal.
Calcd for C15H10ClFO: C, 69.11; H, 3.87. Found: C, 68.78; H,
3.75.
2-(4-F lu or op h en yl)-1-[4-(m eth yloxy)p h en yl]p r op -2-en -1-
on e (4d ): colorless oil; 1H NMR δ 3.86 (s, 3H), 5.55 (s, 1H), 5.96
(s, 1H), 6.92 (d, J ) 8.9 Hz, 2H), 7.03 (t, J ) 8.7 Hz, 2H), 7.38-
7.43 (m, 2H), 7.90 (d, J ) 8.9 Hz, 2H); 13C NMR δ 55.4, 113.6,
115.4 (d, J ) 21.7 Hz), 119.1, 128.6 (d, J ) 8.2 Hz), 129.6, 132.3,
133.2 (d, J ) 3.3 Hz), 147.1, 162.6 (d, J ) 247.9 Hz), 163.7, 195.9.
Anal. Calcd for C16H13FO2: C, 74.99; H, 5.11. Found: C, 74.84;
H, 5.29.
(d, J ) 14.8 Hz, 1H), 6.66 (t, J ) 7.4 Hz, 1H), 7.01 (t, J ) 7.4
Hz, 1H), 7.12-7.20 (m, 4H), 7.30-7.35 (m, 5H), 8.10 (d, J ) 5.9
Hz, 1H); 13C NMR δ -0.0, 27.5, 75.6 (d, J ) 4.0 Hz), 112.6, 116.8
(d, J ) 23.4 Hz), 120.2, 123.8, 124.3, 126.6 (d, J ) 12.0 Hz),
127.8, 127.9 (d, J ) 3.3 Hz), 128.6, 130.3, 130.6 (d, J ) 9.0 Hz),
133.1, 133.4, 138.9, 146.9, 160.1 (d, J ) 248.6 Hz), 192.7. Anal.
Calcd for C24H23ClFN3OSi: C, 63.77; H, 5.31; N, 9.30; found, C,
63.53; H, 5.24; N, 9.20.
2-(1H -1,2,3-Ben zot r ia zol-1-yl)-2-(4-flu or op h en yl)-1-[4-
(m eth yloxy)p h en yl]-3-(tr im eth ylsilyl)p r op a n -1-on e (3d ):
1
colorless glass; H NMR δ -0.18 (s, 9H), 2.43 (d, J ) 14.9 Hz,
1H), 2.49 (d, J ) 15.0 Hz, 1H), 3.73 (s, 3H), 6.66 (d, J ) 9.0 Hz,
2H), 6.99-7.05 (m, 3H), 7.22-7.33 (m, 4H), 7.50 (d, J ) 9.3 Hz,
2H), 8.02-8.04 (m, 1H); 13C NMR δ 0.2, 31.0, 55.3, 76.8, 112.0,
113.5, 115.0 (d, J ) 21.6 Hz), 120.0, 123.9, 127.4, 130.0 (d, J )
7.8 Hz), 131.9, 133.2, 135.1, 146.7, 162.2 (d, J ) 247.0 Hz), 163.1,
193.9. Anal. Calcd for C25H26FN3O2Si: C, 67.09; H, 5.85; N, 9.39;
found, C, 66.97; H, 6.11; N, 9.32.
2-(1H -1,2,3-Ben zot r ia zol-1-yl)-1-(2-ch lor op h en yl)-2-(2-
m eth ylp h en yl)-3-(tr im eth ylsilyl)p r op a n -1-on e (3e): color-
less glass; 1H NMR δ -0.11 (s, 9H), 2.33 (s, 3H), 2.77 (d, J )
14.8 Hz, 1H), 2.95 (d, J ) 15.0 Hz, 1H), 6.68 (d, J ) 7.8 Hz, 1H),
6.76 (d, J ) 7.9 Hz, 1H), 6.97 (t, J ) 7.3 Hz, 1H), 7.20-7.30 (m,
4H), 7.40-7.46 (m, 3H), 7.61 (d, J ) 7.9 Hz, 1H), 8.20 (d, J )
7.2 Hz, 1H); 13C NMR δ -0.1, 19.9, 25.6, 78.9, 113.8, 119.9, 124.1,
124.4, 126.3, 126.8, 127.3, 129.0, 129.5, 130.3, 131.6, 131.8, 132.7,
2-(2-Ch lor op h en yl)-1-(2-m eth ylp h en yl)p r op -2-en -1-on e
1
(4e): colorless oil; H NMR δ 2.46 (s, 3H), 5.98 (s, 1H), 6.13 (s,
1H), 7.19-7.40 (m, 7H), 7.58 (d, J ) 7.5 Hz, 1H); 13C NMR δ
20.1, 124.9, 126.9, 129.4, 129.5, 129.6, 130.5, 131.2, 131.3, 133.0,
137.0, 137.8, 148.9, 197.2. HRMS (EI) (m/e) calcd for C16H13OCl,
256.0655; found, 256.0672.
133.1, 135.4, 136.3, 138.3, 146.8, 196.8. Anal. Calcd for C25H26
-
2-(2-Me t h ylp h e n yl)-1-(4-m e t h ylp h e n yl)p r op -2-e n -1-
on e (4f): white prisms, mp 43.3-44.0 °C; 1H NMR δ 2.27 (s,
3H), 2.43 (s, 3H), 5.99 (s, 1H), 6.10 (s, 1H), 7.12-7.28 (m, 6H),
7.35 (t, J ) 7.5 Hz, 1H), 7.45 (d, J ) 7.6 Hz, 1H); 13C NMR δ
19.9, 20.2, 124.9, 125.7, 128.1, 128.4, 129.6, 130.0, 130.1, 131.0,
131.6, 135.8, 136.9, 137.4, 138.2, 150.4, 198.3. Anal. Calcd for
C17H16O: C, 86.40; H, 6.82. Found: C, 86.32; H, 7.02.
1-(2-Me t h ylp h e n yl)-2-(4-m e t h ylp h e n yl)p r op -2-e n -1-
on e (4 g): colorless oil; 1H NMR δ 2.34 (s, 3H), 2.45 (s, 3H),
5.66 (s, 1H), 6.10 (s, 1H), 7.15-7.23 (m, 4H), 7.32-7.34 (m, 3H),
ClN3O2Si: C, 67.02; H, 5.85; N, 9.38; found, C, 66.60; H, 6.04;
N, 9.39.
2-(1H -1,2,3-Ben zot r ia zol-1-yl)-1-(2-m et h ylp h en yl)-2-(4-
m eth ylp h en yl)-3-(tr im eth ylsilyl)p r op a n -1-on e (3f): colorless
1
glass; H NMR δ -0.20 (s, 9H), 2.04 (s, 3H), 2.29 (s, 3H), 2.54
(s, 2H), 6.66-6.71 (m, 3H), 6.99 (br s, 2H), 7.13-7.27 (m, 5H),
7.34-7.38 (m, 1H), 7.92 (d, J ) 7.8 Hz, 1H); 13C NMR δ -0.3,
(25) Still, W. C.; Kahn, M.; Mitra, A. J . Org. Chem. 1978, 43, 2923.

9986 J . Org. Chem., Vol. 63, No. 26, 1998
Notes
7.43 (d, J ) 7.4 Hz, 1H); 13C NMR δ 20.2, 21.1, 125.2, 125.8,
127.7, 129.0, 129.3, 130.5, 131.1, 133.9, 137.3, 138.1, 138.5, 149.4,
199.6. Anal. Calcd for C17H16O: C, 86.40; H, 6.82. Found: C,
86.09; H, 7.24.
2-[4-(Meth yloxy)p h en yl]-1-(2,4,6-tr im eth ylp h en yl)p r op -
2-en -1-on e (4h ): light yellow prisms, mp 84.8-85.9 °C; 1H NMR
δ 2.21 (s, 6H), 2.31 (s, 3H), 3.84 (s, 3H), 5.78 (s, 1H), 6.17 (s,
1H), 6.86 (s, 2H), 6.93 (d, J ) 8.6 Hz, 2H), 7.44 (d, J ) 8.5 Hz,
2H); 13C NMR δ 19.1, 21.0, 55.2, 113.6, 128.2, 128.4, 129.0, 29.7,
134.2, 137.2, 138.3, 148.6, 159.7, 201.7. Anal. Calcd for
C19H20O: C, 81.40; H, 7.19. Found: C, 81.56; H, 7.45.
P r oced u r e for th e P r ep a r a tion of 2-(4-Ch lor op h en yl)-
1-p h en ylp r op -2-en -1-on e (7): Benzotriazole (0.325 g, 2.72
mmol) and 4-chlorobenzyl chloride (0.337 g, 2.10 mmol) in dry
toluene (3.5 mL) were stirred under reflux for 2 days. The cooled
mixture was sequentially washed with aqueous sodium car-
bonate solution (10%, 2 × 10 mL) and aqueous hydrogen chloride
solution (1 N, 2 × 10 mL). The organic layer was dried (MgSO4),
and the solvent was removed under reduced pressure to afford
a white solid (0.500 g, 2.05 mmol). The solid was dissolved in
THF (20 mL), and the mixture was cooled to -78 °C. n-BuLi in
hexanes (1.55 M, 1.26 mL, 1.95 mmol) was added, and after the
mixture was stirred for 30 min (chloromethyl)trimethylsilane
(0.272 mL, 1.95 mmol) was added; the reaction mixture was
allowed to reach room temperature in 16 h. The mixture was
cooled to -78 °C, and n-BuLi in hexanes (1.55 M, 1.33 mL, 2.05
mmol) was added. After 30 min benzoyl chloride (0.238 mL, 2.05
mmol) was added, and the mixture was allowed to reach room
temperature in 9 h. The solution was washed with saturated
aqueous ammonium chloride solution (50 mL) and extracted with
ethyl acetate (2 × 30 mL). The combined organic layers were
dried (MgSO4), and the solvent was removed under reduced
pressure to afford a pale yellow solid. This solid was dissolved
in dry methylene chloride (8 mL), and trifluoroacetic acid (0.316
mL, 4.11 mmol) was added dropwise under stirring. The result-
ing mixture was allowed to react overnight. The reaction mixture
was washed with aqueous sodium hydroxide solution (5%, 2 ×
20 mL), was extracted with methylene chloride, and was dried
(MgSO4), and the solvent was removed under reduced pressure.
The residue was subjected to flash chromatography on silica gel
to afford 7 as light yellow prisms (0.244 g, 48%): mp 181.4-
1
183.4 °C; H NMR δ 5.67 (s, 1H), 6.07 (s, 1H), 7.31 (d, J ) 8.8
Hz, 2H), 7.36 (d, J ) 8.8 Hz, 2H), 7.44 (t, J ) 7.3 Hz, 2H), 7.56
(t, J ) 7.3 Hz, 1H), 7.88 (d, J ) 7.3 Hz, 2H); 13C NMR δ 121.8,
128.4, 128.8, 129.9, 133.2, 134.4, 135.4, 136.9, 147.1, 201.21.
Anal. Calcd for C15H11ClO: C, 74.22; H, 4.58. Found: C, 74.23;
H, 4.71.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra of compounds 3f-h , and 4e,g (10 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.
J O981725C