Palladium-catalyzed three-component assembling of allenes, organic halides, and arylboronic acids

Article abstract of DOI:10.1021/jo010637g

An efficient method for the construction of two carbon-carbon bonds in a regio- and stereoselective fashion via palladium-catalyzed assembling of allenes, organic halides, and arylboronic acids is described. Organic halides (RI = C₆H₅I, o-, m-, and p-CH₃OC₆H₄I, p-C₂H₅OCOC₆H₄I, p-CH₃COC₆H₄I, p-CH₃C₆H₄I, p-CH₃C₆H₄Br, p-CH₃C₆H₄Cl, p-NO₂C₆H₄I, p-NO₂C₆H₄Br, p-NO₂C₆H₄Cl, p-IC₆H₄Cl, 1-iodonaphthalene, 2-iodothiophene, 3-iodo-2-cyclopenten-1-one, 3-iodo-5,5-dimethyl-2-cyclohexen-1-one, C₆H₅(Br)C=CH₂ and ICH₂CO₂C₂H₅), and arylboronic acids (ArB(OH)₂, Ar = C₆H₅, p-CH₃-OC₆H₄, m-NO₂C₆H₄, p-FC₆H₄, 1-C₁₀H₇, and o-, m-, and p-CHOC₆H₄) undergo Suzuki-type three-component assembling with 1,1-dimethylallene to give the corresponding allylic derivatives, (CH₃)₂=CRCH₂Ar, in DMF at 70°C in the presence of CsF using Pd(dba)₂ as the catalyst. Higher yields of products were obtained for aryl iodides than for the corresponding aryl bromides and chlorides. This three-component assembling is highly regioselective, with the organic group on halides adding to the middle carbon and the aryl group on arylboronic acids to the unsubstituted terminal carbon of allenes. Monosubstituted allenes 1b-e (cyclopentylallene, cyclohexylallene, tertbutylallene, and n-butylallene) also undergo similar assembling reaction with organic halides and arylboronic acids to afford the corresponding products 7a-i with high regio- and stereoselectivity. Based on the known palladium chemistry, a mechanism is proposed to account for the catalytic reaction and the stereochemistry.

Full text of DOI:10.1021/jo010637g

J . Org. Chem. 2002, 67, 99-105
99
P a lla d iu m -Ca ta lyzed Th r ee-Com p on en t Assem blin g of Allen es,
Or ga n ic Ha lid es, a n d Ar ylbor on ic Acid s
Tai-Hsiang Huang, Hao-Ming Chang, Ming-Yuan Wu, and Chien-Hong Cheng*
Department of Chemistry, Tsing Hua University, Hsinchu, Taiwan
chcheng@mx.nthu.edu.tw
Received J une 22, 2001
An efficient method for the construction of two carbon-carbon bonds in a regio- and stereoselective
fashion via palladium-catalyzed assembling of allenes, organic halides, and arylboronic acids is
described. Organic halides (RI ) C6H5I, o-, m-, and p-CH3OC6H4I, p-C2H5OCOC6H4I, p-CH3COC6H4I,
p-CH3C6H4I, p-CH3C6H4Br, p-CH3C6H4Cl, p-NO2C6H4I, p-NO2C6H4Br, p-NO2C6H4Cl, p-IC6H4Cl,
1-iodonaphthalene, 2-iodothiophene, 3-iodo-2-cyclopenten-1-one, 3-iodo-5,5-dimethyl-2-cyclohexen-
1-one, C6Η5(Br)CdCH2 and ICH2CO2C2H5), and arylboronic acids (ArB(OH)2, Ar ) C6H5, p-CH3-
OC6H4, m-NO2C6H4, p-FC6H4, 1-C10H7, and o-, m-, and p-CHOC6H4) undergo Suzuki-type three-
component assembling with 1,1-dimethylallene to give the corresponding allylic derivatives,
(CH3)2dCRCH2Ar, in DMF at 70 °C in the presence of CsF using Pd(dba)2 as the catalyst. Higher
yields of products were obtained for aryl iodides than for the corresponding aryl bromides and
chlorides. This three-component assembling is highly regioselective, with the organic group on
halides adding to the middle carbon and the aryl group on arylboronic acids to the unsubstituted
terminal carbon of allenes. Monosubstituted allenes 1b-e (cyclopentylallene, cyclohexylallene, tert-
butylallene, and n-butylallene) also undergo similar assembling reaction with organic halides and
arylboronic acids to afford the corresponding products 7a -i with high regio- and stereoselectivity.
Based on the known palladium chemistry, a mechanism is proposed to account for the catalytic
reaction and the stereochemistry.
Sch em e 1
In tr od u ction
Organoboronic acids are widely used in the palladium-
catalyzed Suzuki cross-coupling with aryl or vinylic
halides providing a very efficient route for carbon-carbon
bond formation.1 A practical advantage of the Suzuki
reaction relative to many other cross-coupling processes
is the mild nature of boronic acids that are readily
prepared, nontoxic and thermally, air-, and moisture-
stable, as well as compatibility with diverse functional
groups.2 While the cross coupling of organoboronic acids
with aryl or vinylic halides has been well studied,1,3 the
application of these mild reagents in other reactions is
much less documented.4 Scattered reports on the aryla-
tion or alkenylation by organoboronic acids of palladium1a,5
and nickel6 π-allyl complexes are known. An extension
of Suzuki cross coupling is the Suzuki-type three-
component assembling reaction (Scheme 1).7 The devel-
opment of an efficient and general method for this three-
component assembling reaction is highly attractive in
view of the power to form two carbon-carbon bonds in a
single reaction.8
Recently, much attention has been drawn to the
chemistry of allenes,9 a class of unsaturated organic
(4) (a) Miyaura, N.; Yamada, K.; Suginome, H.; Suzuki, A. J . Am.
Chem. Soc. 1985, 107, 972-980. (b) Miyaura, N.; Tanabe, Y.; Suginome,
H.; Suzuki, A. J . Organomet. Chem. 1982, 233, C13-C16. (c) Yatagai,
H. Bull. Chem. Soc. J pn. 1980, 53, 1670-1676. (d) Miyaura, N.; Yano,
T.; Suzuki, A. Tetrahedron Lett. 1980, 21, 2865-2868. (e) Miyaura,
N.; Suginome, H.; Suzuki, A. Tetrahedron Lett. 1984, 25, 761-764. (f)
Kobayashi, Y.; Ikeda, E. J . Chem. Soc., Chem. Commun. 1994, 1789-
1790. (g) Parrish, C. A.; Buchwald, S. L. J . Org. Chem. 2001, 66, 3820-
3827. (h) LeBlond, C. R.; Andrews, A. T.; Sun, Y.; Sowa, J . R., J r.,
Org. Lett. 2001, 3, 1555-1557. (i) Hartwig, J . F. Angew. Chem., Int.
Ed. 1998, 37, 2046-2067. (j) Wolfe, J . P.; Wagaw, S.; Marcoux, J .-F.;
Buchwald, S. L. Acc. Chem. Res. 1998, 31, 805-818.
(1) For reviews, see: (a) Miyaura, N.; Suzuki, A. Chem. Rev. 1995,
95, 2457-2483. (b) Suzuki, A. J . Organomet. Chem. 1999, 576, 147-
168. (c) Miyaura, N. In Advances in Metal-Organic Chemistry, Liebe-
skind, L. S., Ed.; J AI: London, 1998; Vol. 6, pp 187-243. (d) Suzuki,
A. In Metal-Catalyzed Cross-Coupling Reactions; Diederich, F., Stang,
P. J ., Eds.; Wiley-VCH: New York, 1998; Chapter 2. (e) Stanforth, S.
P. Tetrahedron 1998, 54, 263-303.
(2) (a) Littke, A. F.; Dai, C.; Fu, G. C. J . Am. Chem. Soc. 2000, 122,
4020-4028. (b) Occhiato, E. G.; Trabocchi, A.; Guarna, A. J . Org. Chem.
2001, 66, 2459-2465. (c) Davies, M. W.; J ohnson, C. N.; Narrity, J . P.
A. J . Org. Chem. 2001, 66, 3525-3532.
(5) Snieckus, V. Chem. Rev. 1990, 90, 879-939.
(6) (a) Saito, S.; Oh-tani, S.; Miyaura, N. J . Org. Chem. 1997, 62, 2,
8024-8030. (b) Saito, S.; Sakai, M.; Miyaura, N. Tetrahedron Lett.
1996, 37, 2993-2996. (c) Galland, J .-C.; Savignac, M.; Geneˆt, J .-P.
Tetrahedron Lett. 1999, 40, 2323-2326. (d) Lipshutz, B. H.; Sclafani,
J . A.; Blomgren, P. A. Tetrahedron 2000, 56, 2139-2144. (e) Indolese,
A. F. Tetrahedron Lett. 1997, 38, 3513-3516.
(3) (a) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 1998, 37,
3387-3388. (b) Grushin, V. V.; Alper, H. Chem. Rev. 1994, 94, 1047-
1062. (c) Stu¨rmer, R. Angew. Chem., Int. Ed. 1999, 38, 3307-3308.
(d) Kocovsky, P.; Vyskocil, S.; Cisarova, I.; Sejbal, J .; Tislerova, I.;
Smrcina, M.; Lloyd-J ones, G. C.; Stephen, S. C.; Butts, C. P.; Murray,
M.; Langer, V. J . Am. Chem. Soc. 1999, 121, 7714-7715. (e) Beller,
M.; Fischer, H.; Herrmann, W. A.; Ofele, K.; Brossmer, C. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1848-1849.
(7) (a) Chatani, N.; Amishiro, N.; Murai, S. J . Am. Chem. Soc. 1991,
113, 7778-7780. (b) Ikeda, S. I.; Sato, Y. J . Am. Chem. Soc. 1994, 116,
5975-5976. (c) Ikeda, S. I.; Cui, D. M.; Sato, Y. J . Org. Chem. 1994,
59, 6877-6878. (d) Nakamura, H.; Shim, J . G.; Yamamoto, Y. J . Am.
Chem. Soc. 1997, 119, 8113-8114.
(8) Tsuji, J .; Shimizu, I. Chem. Lett. 1984, 233-236.
(9) Zimmer, R.; Dinesh, C. U.; Nandanan, E.; Khan, F. A. Chem.
Rev. 2000, 100, 3067-3125.
10.1021/jo010637g CCC: $22.00 © 2002 American Chemical Society
Published on Web 12/08/2001

100 J . Org. Chem., Vol. 67, No. 1, 2002
Huang et al.
Ta ble 1. Effect of Rea ction Con d ition s on th e Yield s of
th e Th r ee-Com p on en t Assem blin g of 1,1-Dim eth yla llen e,
p-Iod oa n isole, a n d P h en ylbor on ic Acid a
substrates with unique reactivity in the three-component
assembling reaction.10 An allene can insert rapidly into
a metal-carbon bond from oxidative addition of an
organic halide to the metal catalyst to give a π-allyl
species that is reasonably stable to â-hydride elimina-
tion.11 Attack of the π-allyl species by a nucleophile led
to the three-component assembling product.12 Several
types of electrophile including acyl, aryl, and vinylic
halides and nucleophiles such as amines, alkoxides, and
stable carbon anions are known13 in this palladium-
catalyzed addition to allenes,9 but low stereo- and regi-
oselectivity were encountered in most cases.14 Our inter-
est in the palladium-catalyzed allene reactions has led
us to successfully develop several regio- and stereoselec-
tive three-component assembling reactions of allenes.10,12
In view of the ability of arylboronic acids as nucleophiles
to attack palladium π-allyl species, we investigated the
three-component assembling of organic halides, allenes,
and arylboronic acids catalyzed by palladium complexes.
The key to the success of the reaction lies on the choice
of a proper base and solvent that can activate organobo-
ronic acids15 but without deprotonating the palladium
π-allyl species to give the diene products.12a In this paper,
we wish to report that by using Pd(dba)2 as catalyst in
the presence of CsF in DMF, the Suzuki-type three-
component assembling proceeds smoothly. The reaction
is compatible with various functional groups and provides
an efficient method for preparing several types of organic
compounds such as dienes, dienenones, and various
substituted allylic species. Moreover, the reaction con-
structs two carbon-carbon bonds chemo-, regio-, and
stereoselectively under mild conditions.
yield (%)b
temp (°C)
entry
Pd catalyst
base, solvent
time (h) 4d
5
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Pd(OAc)2
PdCl2(PPh3)2
Pd(dba)2
Pd(dba)2/1PPh3 CsF/DMF
Pd(dba)2/2PPh3 CsF/DMF
Pd(dba)2/4PPh3 CsF/DMF
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
Pd(dba)2
CsF/DMF
CsF/DMF
CsF/DMF
70/7
70/7
70/7
70/7
70/7
70/7
70/48
70/12
70/7
67 - - 10
17 - - 53
88 - - - -
57 - - - -
40 - - - -
- - - - - -
- - - - - -
51 14 10
- - 12 63
- -/DMF
K2CO3/DMF
NaOH/DMF
Cs2CO3/DMF 70/12
Na2CO3/DMF 70/12
Li2CO3/DMF 70/12
CsF/DMF
CsF/DMF
CsF/DMF
CsF/CH3CN
CsF/THF
46
37 10
- -
9
- -
8
- -
9
rt/24
50/17
90/7
- - - - - -
51 - - 10
80
8
- -
70/24
12 - - 23
reflux/24 20 - - 32
70/48
reflux/24
70/48
CsF/Toluene
CsF/CH2Cl2
CsF/Et3N
26 - - 10
- - - - - -
- - 15 44
a
All reactions were carried out under the following conditions:
1,1-dimethylallene (1a , 1.00 mmol), p-iodoanisole (2d , 0.50 mmol),
phenylboronic acid (3a , 0.750 mmol), Pd complex (0.0250 mmol),
b
base (1.50 mmol), and solvent (2.5 mL). Isolated yields are based
on p-iodoanisole.
The yield of product 4d depends greatly on the pal-
ladium catalyst, ligand, base, solvent, and temperature
employed. Table 1 summarizes the results of these
studies. Of the several solvents tested, DMF gave the
highest yield of 4d . The other solvents including CH3-
CN, THF, toluene, CH2Cl2, and Et3N showed either low
chemoselectivity or low yield of product 4d . Two side
products 512a and 6 from the reaction were detected
depending on the solvent used (eq 1). The three-
Resu lts a n d Discu ssion
Rea ction Con d ition s for Th r ee-Com p on en t As-
sem blin g. Treatment of 1,1-dimethylallene (1a ) with
p-iodoanisole (2d ) and phenylboronic acid (3a ) in the
presence of CsF catalyzed by Pd(dba)2 in DMF at 70 °C
for 7 h gave three-component assembling product 4d in
88% isolated yield. No other product was observed,
indicating that the reaction is highly chemo- and regi-
oselective. Spectral data of this product showed that the
p-MeOC6H4 and C6H5 groups were added to the middle
and unsubstituted terminal carbons, respectively, of the
allene moiety.
(10) (a) Cheng, C. H.; Wu, M. Y.; Yang, F. Y. J . Org. Chem. 1999,
64, 2471-2474. (b) Cheng, C. H.; Yang, F. Y.; Wu, M. Y. Tetrahedron
Lett. 1999, 40, 6055-6058. (c) Chang, H. M.; Cheng, C. H. J . Chem.
Soc., Perkin Trans. 2000, 1, 3799-3807. (d) Yang, F, Y.; Wu, M. Y.;
Cheng, C. H. J . Am. Chem. Soc. 2000, 122, 7122-7123. (e) Yang, F,
Y.; Cheng, C. H. J . Am. Chem. Soc. 2001, 123, 761-762.
(11) (a) Besson, L.; Gore´, J .; Cazes, B. Tetrahedron Lett. 1995, 36,
3853-3856. (b) Anie`s, C.; Cazes, B.; Gore´, J . J . Chem. Res. (S) 1996,
116-117. (c) Vicrat, N.; Cazes, B.; Gore´, J . Tetrahedron 1996, 52,
9101-9110. (d) Yamamoto, Y.; Al-Masum, M.; Asao, N. J . Am. Chem.
Soc. 1994, 116, 6019-6020. (e) Larock, R. C.; Tu, C.; Pace, P. J . Org.
Chem. 1998, 63, 6859-6866. (f) Larock, R. C.; He, Y.; Leong, W. W.;
Han, X.; Refvik, M. D.; Zenner, J . M. J . Org. Chem. 1998, 63, 2154-
2160.
(12) (a) Chang, H. M.; Cheng, C. H. J . Org. Chem. 2000, 65, 1767-
1773. (b) Chang, H. M.; Cheng, C. H. Org. Lett. 2000, 2, 3439-3442.
(13) Malleron, J .-L.; Fiaud, J .-C.; Legros, J .-Y. Handbook of Pal-
ladium-Catalyzed Organic Reactions; Academic Press: San Diego,
1997.
(14) Grigg, R.; Sansano, J . M.; Santhakumar, V.; Sridharan, V.;
Thangavelanthum, R.; Thornton-Pett, M.; Wilson, D. Tetrahedron
1997, 53, 11803-11826.
component assembling reaction requires the presence of
a base (entries 3 and 7) to promote the reactivity of
boronic acid 3a .15 However, a strong base such as NaOH
greatly increases the direct coupling product 6 and diene
512a (entry 9). The use of weaker base such as K2CO3,
Cs2CO3, or Na2CO3, improves the yield of 4d , but side
products 5 and 6 are still produced in substantial
amount. Of the bases tested, CsF appears to be the best
giving product 4d with essentially no side products 5 and
6 detected. The effect of palladium complex and ligand
on the catalytic activity was also investigated (entries
1-6). Phosphine-free palladium complexes Pd(OAc)2 and
Pd(dba)2 catalyze this reaction smoothly, but the latter
appears superior over the former in view of the selectivity
of product 4d (entry 3). The presence of PPh3 inhibits
the catalytic reaction; the yield of product 4d decreases
with increasing PPh3/Pd ratio.
(15) (a) Suzuki, A. Acc. Chem. Res. 1982, 15, 178-184. (b). Miyaura,
N.; Ishiyama, T.; Ishikawa, M.; Suzuki, A.; Sasaki, H.; Satoh, M. J .
Am. Chem. Soc. 1989, 111, 314-321. (c) Suzuki, A. Pure Appl. Chem.
1994, 66, 213-222.

Pd-Catalyzed Three-Component Assembling
J . Org. Chem., Vol. 67, No. 1, 2002 101
Ta ble 2. Resu lts of Th r ee-Com p on en t Assem blin g of
1,1-Dim eth yla llen e, Or ga n ic Ha lid es, a n d P h en ylbor on ic
Acid a
Sch em e 2
Cl, p-IC6H4Cl, and 1-iodonaphthalene react smoothly
with 1,1-dimethylallene (1a ) and phenylboronic acid (3a )
to yield the corresponding three-component assembling
products in good to excellent yields (Table 2, entries
1-14). It is noteworthy that an electron-withdrawing or
electron-donating substituent on aryl iodides does not
significantly affect the product yield. However, aryl
iodides with an ortho-substitutent such as o-iodoanisole
and 1-iodonaphthalene clearly give lower yields of the
assembling products. Aryl bromides also react with 1a
and 3a efficiently to provide the expected products, but
the yields are slightly lower than those of the corre-
sponding aryl iodides (entries 8 and 11). The reaction of
most aryl chlorides with 1a and 3a was very slow, and
low yields of the desired products were obtained (entries
9 and 12). For aryl chlorides, the presence of an electron-
withdrawing substituent (entry 12) improves the yields
of assembling products significantly. These results may
be understood based on the fact that an electron-with-
drawing group on aryl halide generally enhances the rate
of oxidative addition to the palladium center.16 As ex-
pected, the reaction of 1-chloro-4-iodobenzene (2m ) with
1a and 3a gave product 4i with the 4-chlorophenyl in-
stead of 4-iodophenyl group attached to the middle carbon
of the 1,1-dimethylallene moiety, a result of the fact that
cleavage of C-I bond is much faster than that of the
C-Cl bond. Heterocyclic compound, 2-iodothiophene, also
undergoes assembling reaction with 1a and 3a to give
product 4k in 91% yield (entry 15). A number of alkenyl
iodides including 3-iodo-2-cyclopenten-1-one, 3-iodo-5,5-
dimethyl-2-cyclohexen-1-one, and R-bromostyrene were
also tested for the assembling reactions with 1a and 3a
(entries 17-19). All these reactions proceed smoothly to
give in 62-68% yield the corresponding dienones or
dienes that are known to be very useful in organic
synthesis. An example of alkyl iodide, ethyl 2-iodoacetate
(2p ), was used in the three-component assembling with
1a and 3a (entry 16). The reaction went on readily to
give the expected product albeit in only 42% yield.
Under similar reaction conditions, arylboronic acids
3b-h (ArB(OH)2, Ar ) C6H5, p-CH3OC6H4, m-NO2C6H4,
p-FC6H4, 1-C10H7, and o-, m-, and p-CHOC6H4) also react
efficiently with 1,1-dimethylallene (1a ) and p-iodoanisole
(2d ) (Scheme 2) to give the corresponding three-compo-
nent assembling products in moderate to excellent yields.
a
All reactions were carried out under the following conditions:
1a (1.00 mmol), organic halide 2 (0.500 mmol), 3a (0.750 mmol),
5 mol % Pd(dba)2 (0.0250 mmol), CsF (1.50 mmol), and DMF (2.5
b
mL), and reaction time, 7 h. Isolated yields are based on organic
halide. c Reaction time is 12 h.
Th r ee-Com p on en t Assem blin g of 1,1-Dim eth yla -
llen e, Or ga n ic Ha lid es, a n d Ar ylbor on ic Acid s. The
three-component assembling can be successfully extended
to a variety of organic halides by carrying out the
reactions in DMF at 70 °C in the presence of CsF. Thus,
aryl iodides including C6H5I, o-, m-, and p-CH3OC6H4I,
p-C2H5OCOC6H4I,p-CH3COC6H4I,p-CH3C6H4I,p-CH3C6H4-
Br, p-CH3C6H4Cl, p-NO2C6H4I, p-NO2C6H4Br, p-NO2C6H4-
(16) Tsuji, J . In Palladium Reagents and Catalysts: Innovations in
Organic Synthesis; J ohn Wiley & Sons: Chichester, 1995.

102 J . Org. Chem., Vol. 67, No. 1, 2002
Huang et al.
Ta ble 3. Th r ee-Com p on en t Assem blin g of
n-Butylboronic acid (3i), however, failed to give the
desired products suggesting that alkylboronic reagents
are difficult to react with π-allylpalladium(II) complexes.1a
Th r ee-Com p on en t Assem b lin g of Mon osu b st i-
tu ted Allen es. Monosubstituted allenes including cy-
clopentyl- (1b), cyclohexyl- (1c), tert-butyl- (1d ), and
n-butylallene (1e) undergo this Suzuki-type three-
component assembling with organic iodides (2a and 2d )
and arylboronic acids (3a -c and 3l) efficiently, producing
highly regioselective and stereoselective allylic deriva-
tives 7a -i in 69-85% yields (eq 2). The results of these
Mon osu bstitu ted Allen es w ith Ar yl Iod id es a n d
Ar ylbor on ic Acid sa
studies are listed in Table 3. The stereoselectivity of these
products depends greatly on the substituent on the
allene. A bulkier substituent on the allene gives products
with higher E/Z ratios. In all cases, the E isomer was
observed as the major product. For example, the reaction
of tert-butylallene (1d ), p-iodoanisole (2d ), and p-fluo-
rophenylboronic acid (3c) gave product 7f with a E/Z ratio
of 97/3 (entry 6). Other three-component assembling
reactions of monosubstituted allenes, aryl iodides, and
arylboronic acids afforded allylic derivatives with the E/Z
ratios between 73/27 and 96/4.
The stereochemistry of these three-component as-
1
sembling products was determined using the typical H
NMR NOE technique. For instance, there are two iso-
mers (E)-7c and (Z)-7c isolated from the reaction of 1c,
2a , and 3a (Scheme 3). The minor product (Z)-7c exhibits
1H NMR signals at 3.59 and 5.32 ppm for the methylene
(Ha) and olefin proton (Hb), respectively. Irradiation at
Ha signal led to an increase of the Hb intensity by 5.97%.
Similarly, irradiation at the Hb signal resulted in an
increase of the Ha intensity by 5.96%. In contrast,
irradiation at the methylene (Hc) and the olefin proton
(Hd) signals of the major product, (E)-7c, showed es-
sentially no change of the intensity of Hd and Hc signals,
respectively. These NOE results unambiguously deter-
mine the stereochemistry of these two stereoisomers.
Other pairs of E/Z isomers are also established by similar
techniques.
a
All reactions were carried out using allene (1, 1.00 mmol), aryl
iodide (2, 0.50 mmol), arylboronic acid (3, 0.750 mmol), Pd(dba)2
(0.0250 mmol), CsF (1.500 mmol), and DMF (2.5 mL); reaction time
is 7 h. Isolated yields are based on aryl iodide. c The E/Z ratio
b
was calculated from NMR peak intensities.
Sch em e 3
The formation of E isomers from monosubstituted
allenes is surprising in view of the fact that most
carbopalladation reactions of monosubstituted allenes
reported gave E and Z isomeric products with low
selectivity.11 To account for the present stereoselectivity,
a mechanism based on face-selective coordination of
allenes to the palladium center is proposed.10d The
terminal double bond of allene is coordinated to the
palladium moiety at the face opposite to the substituents
R1 favorably to avoid steric congestion (Scheme 4).
Coordination of the terminal double bond at the other
face or coordination of the internal double bond to the
palladium center will lead to a great increase of steric
repulsion and is less favorable. As shown in Scheme 4,
the face-selective coordination results in a π-allylpalla-
dium species with the R1 group anti to the organic moiety
R. Further reaction with arylboronic acid 3 affords
product with E stereochemistry. It is necessary that the
latter step is faster than the syn-anti rearrangement of
π-allylpalladium species to obtain high E selectivity.
The presence of phosphorus ligand in the catalytic
reaction immensely effects on the stereo- and regioselec-
tivity of the three-component assembling product. Several
phosphorus ligands, P(o-tol)3, P(OPh)3, PPh2Me, and dppe

Pd-Catalyzed Three-Component Assembling
J . Org. Chem., Vol. 67, No. 1, 2002 103
Sch em e 4
Ta ble 4. Effect of P h osp h or u s Liga n d s on th e
Sch em e 5
Th r ee-Com p on en t Assem blin g of Cycloh exyla llen e w ith
Iod oben zen e a n d P h en ylbor on ic Acid a
entry
ligand
- -
P(o-tol)3
P(OPh)3
2 PPh3
PPh2Me
dppe
yield (%)b
product ratio (E-7c/Z-7c/7′)c
1
2
3
4
5
6
7
85
70
68
40
50
30
- -
75/25/- -
64/35/1
60/39/1
50/18/32
84/12/4
70/20/10
- -
2 dppe
a
All reactions were carried out using cyclohexylallene (1c, 2.00
mmol), iodobenzene (2a , 1.00 mmol), phenylboronic acid (3a , 1.50
mmol), 5 mol % Pd(dba)2 (0.0500 mmol), ligand (0.0500-0.1000
mmol), CsF (4.50 mmol), and DMF (5.0 mL); reaction time is 7 h.
b
Isolated yields are based on iodobenzene. c The E/Z ratio was
calculated from NMR spectra of the reaction mixture.
(1,2-bis(diphenylphosphino)ethane), were tested in the
reaction of cyclohexylallene (1c) with 2a and 3a (eq 3)
Mech a n ism . On the basis of the known palladium
chemistry,15 we propose a catalytic cycle as illustrated
in Scheme 5 to account for the present Suzuki-type three-
component assembling. The catalytic reaction is initiated
by oxidative addition of organic halide to palladium(0)
to give Pd(II) intermediate. Allene insertion to the
organopalladium complex produces a π-allylpalladium
intermediate. Transmetalation with arylboronic reagent
with the assistance of a base18 followed by reductive
elimination provides the observed product and regener-
ates the palladium(0) catalyst. The observation that
phosphorus ligands diminish the yield of the three-
component-coupling products may be understood in view
of the fact that strong donor ligands are known to impede
olefin coordination/insertion, which is central to the
success of the present three-component assembling reac-
tion.
catalyzed by Pd(dba)2. The yields and E/Z ratios of these
reactions are summarized in Table 4. It is clear that Pd-
(dba)2 in the absence of a phosphorus ligand is most
active and most regio- and stereoselective. The reaction
required 7 h for completion at 70 °C using Pd(dba)2 alone
and gave product 7c in 85% yield with a E/Z ratio of 75/
25. Addition of phosphorus ligands to the reaction
mixture greatly decreased the product yields and E/Z
ratios of the products. In addition to the E/Z stereoiso-
mers 7c, regioisomer 7c′, in which a phenyl group and
the cyclohexyl group are both attached to the same
carbon, was also observed. The decrease in E/Z ratio for
monosubstituted allenes in the presence of a phosphorus
ligand may be explained based on the fact that donor
ligands readily promote anti-syn rearrangement of π-al-
lylpalladium species via a σ-allylpalladium intermedi-
ate.17 The anti and syn forms of π-allylpalladium com-
plexes (Scheme 4) are responsible for the formation of E
and Z isomers of allylic derivatives, respectively.
Con clu sion
We have successfully developed a palladium-catalyzed
three-component assembling of allenes, organic halides,
and arylboronic acids for the preparation of various types
of organic compounds. A wide range of organic halides,
arylboronic acids, and allenes may be used in this
reaction. The catalysis assembles three different organic
fragments together, constructing two carbon-carbon
(18) (a) Onak, T. Organoborane Chemistry; Academic: New York,
1975. (b) Mikhailov, B. M.; Bubnov, Y. N. Organoboron Compounds
in Organic Synthesis; Harwood Academic Pub.: Amsterdam, 1983. (c)
Pelter, A.; Smith, K.; Brown, H. C. Borane Reagents; Academic: New
York, 1988. (d) Wright, S. W.; Hageman, D. L.; McClure, L. D. J . Org.
Chem. 1994, 59, 6095-6097.
(17) (a) Tibbets, D. L.; Brown, T. L. J . Am. Chem. Soc. 1970, 92,
3031-3034. (b) Powell, J .; Shaw, B. L. J . Chem. Soc. (A) 1967, 1839.

104 J . Org. Chem., Vol. 67, No. 1, 2002
Huang et al.
(s), 145.26 (s), 159.07 (s); HRMS calcd for C18H20O 252.1514,
found 252.1511.
bonds in a regio- and stereoselective fashion. Further
application of this powerful method in complicated
organic compounds is in progress.
1-(1-Ben zyl-2-m et h yl-1-p r op en yl)-4-m et h oxyb en zen e
1
(4d ). H NMR (400 MHz, CDCl3) δ 1.56 (s, 3 H), 1.91 (s, 3 H),
3.71 (s, 2 H), 3.76 (s, 3 H), 6.76 (d, J ) 8.8 Hz, 2 H), 6.92 (d,
J ) 8.8 Hz, 2 H), 7.05-7.25 (m, 5 H); 13C NMR (100 MHz,
CDCl3) δ 20.84 (q), 22.29 (q), 40.52 (t), 55.10 (q), 113.13 (d),
125.55 (d), 128.09 (d), 128.48 (d), 129.33 (s), 130.00 (d), 132.91
(s), 136.09 (s), 140.46 (s), 157.59 (s); IR (neat) 3062, 3048, 2983,
1605, 1505, 1417, 1251, 1177, 1034, 913, 915 cm-1; HRMS calcd
for C18H20O 252.1514, found 252.1510.
Exp er im en ta l Section
Gen er a l Com m en ts. All reactions were carried out under
a nitrogen atmosphere unless otherwise mentioned and in
oven-dried glassware. All solvents were dried according to
known methods and distilled prior to use.19 PdCl2(PPh3)2,20 Pd-
(dba)2,21 1,1-dimethylallene,22 cyclohexylallene,23 cyclopenty-
lallene,23 n-butylallene,23 tert-butylallene,23 3-iodo-2-cyclopenten-
1-one,24 and 3-iodo-5,5-dimethyl-2-cyclohexen-1-one24 were
prepared by procedures previously reported. Other reagents
were commercially available and used as purchased.
Gen er a l P r oced u r e for th e Th r ee-Com p on en t As-
sem blin g of Allen es, Or ga n ic Ha lid es, a n d Ar ylbor on ic
Acid s. A 25-mL round-bottom flask containing Pd(dba)2
(0.0144 g, 0.0250 mmol), arylboronic acid (0.750 mmol), organic
halide (0.500 mmol), and CsF (0.455 g, 1.50 mmol) was purged
with nitrogen gas several times. To the flask were added DMF
(2.50 mL) and allene (1.00 mmol). The reaction mixture was
heated with stirring at 70 °C for 7 h. The solution changed
color from purple red to black in 2 h and maintained at the
same color during the reaction. As the reaction approached
completion, a black precipitate of palladium metal surrounding
the wall of the flask appeared gradually. At the end of the
reaction, the solution was diluted with ether (30 mL) and
extracted with ether and water. The organic layer was collected
and dried over MgSO4. After solvent removal by a rotary
evaporator, the residue was separated on a silica gel column
using hexane and ethyl acetate as eluent to give the desired
product.
2-(1-Ben zyl-2-m et h yl-1-p r op en yl)t h iop h en e (4k ). 1H
NMR (300 MHz, CDCl3) δ 1.87 (s, 3 H), 1.95 (s, 3 H), 3.78 (s,
2 H), 6.65-7.28 (m, 8 H); 13C NMR (75 MHz, CDCl3) δ 21.40
(q), 22.82 (q), 41.04 (t), 123.68 (d), 125.82 (d), 126.26 (d), 126.37
(d), 128.19 (d), 128.35 (d), 133.35 (s), 140.01 (s), 145.25 (s); IR
(neat) 3026, 2918, 1601, 1493, 1445, 1375, 1225, 1114, 1029,
849, 697, 526 cm-1; HRMS calcd for C15H16S 228.0972, found
228.0975.
Eth yl 3-Ben zyl-4-m eth yl-3-p en ten oa te (4l). 1H NMR
(400 MHz, CDCl3) δ 1.21 (t, J ) 7.2 Hz, 3 H), 1.81 (s, 3 H),
1.87 (s, 3 H), 2.99 (s, 2 H), 3.54 (s, 2 H), 4.06 (q, J ) 7.2 Hz, 2
H), 7.13-7.29 (m, 5 H); 13C NMR (100 MHz, CDCl3) δ 14.13
(q), 20.91 (q), 37.26 (t), 38.35 (t), 60.32 (t), 124.28 (s), 125.92
(d), 128.29 (d), 128.61 (d), 130.84 (s), 140.05 (s), 172.14 (s); IR
(neat) 3029, 2942, 1733, 1598, 1493, 1449, 1262, 1164, 1032,
703 cm-1; GC-EIMS m/z (rel intensity) 232 (M+, 100), 186 (25),
142 (24), 116 (10); HRMS calcd for C15H20O2 232.1458, found
232.1471.
3-(1-Be n zyl-2-m e t h yl-1-p r op e n yl)-2-cyclop e n t e n -1-
1
on e (4m ). H NMR (400 MHz, CDCl3) δ 1.80 (s, 3 H), 1.83 (s,
3 H), 2.22-2.25 (m, 2 H), 2.45-2.49 (m, 2 H), 3.56 (s, 2 H),
5.83 (s, 1 H), 7.00-7.19 (m, 5 H); 13C NMR (100 MHz, CDCl3)
δ 21.16 (q), 22.44 (q), 31.25 (t), 34.49 (t), 36.46 (t), 125.77 (d),
127.59 (d), 128.07 (d), 128.87 (s), 131.64 (d), 134.59 (s), 138.70
(s), 178.88 (s), 209.55 (s); IR (neat) 3026, 2921, 1697, 1593,
1493, 1444, 1277, 1177, 701 cm-1; GC-EIMS m/z (rel intensity)
227 (M+ + 1, 100), 208 (8), 141 (15), 91 (11); HRMS calcd for
Compounds 4a -v and 7a -i were prepared according to this
method. Product yields of these reactions are listed in Table 2
and Table 3, while important spectral data of these allylic
compounds are shown below or listed in Supporting Informa-
tion.
C
16H18O 226.1353, found 226.1352.
1-(1-Ben zyl-2-m eth yl-1-p r op en yl)ben zen e (4a ). 1H NMR
(400 MHz, CDCl3) δ 1.65 (s, 3 H), 1.93 (s, 3 H), 3.73 (s, 2 H),
6.99-7.25 (m, 10 H); 13C NMR (100 MHz, CDCl3) δ 20.80 (q),
22.25 (q), 40.43 (t), 125.59 (d), 125.81 (d), 127.74 (d), 128.10
(d), 128.47 (d), 128.98 (d), 129.52 (s), 133.46 (s), 140.31 (s),
143.77 (s); IR (neat) 3059, 3025, 2916, 1600, 1492, 1447, 1072,
1029, 1013, 702, 582 cm-1; GC-EIMS m/z (rel intensity) 222
(M+, 100), 207 (38), 143 (20), 129 (25); HRMS calcd for C17H18
222.1404, found 222.1413.
3-(1-Ben zyl-2-m eth yl-1-p r op en yl)-5,5-d im eth yl-2-cyclo-
h exen -1-on e (4n ). 1H NMR (300 MHz, CDCl3) δ 0.93 (s, 6
H), 1.73 (s, 3 H), 1.82 (s, 3 H), 2.07 (s, 2 H), 2.13 (s, 2 H), 3.52
(s, 2 H), 5.67 (s, 1 H), 7.05-7.26 (m, 5 H); 13C NMR (75 MHz,
CDCl3) δ 20.66 (q), 22.04 (q), 28.21 (q), 33.65 (s), 37.11 (t), 43.72
(t), 50.98 (t), 126.12 (d), 127.32 (d), 128.35 (d), 128.38 (d),
129.98 (s), 132.96 (s), 139.30 (s), 163.08 (s), 184.58 (s); HRMS
calcd for C19H24O (M+ + 1) 269.1905, found 269.1905.
1-[3-Meth yl-2-(1-p h en ylvin yl)-2-bu ten yl]ben zen e (4o).
1H NMR (300 MHz, CDCl3) δ 1.81 (s, 3 H), 1.98 (s, 3 H), 3.45
(s, 2 H), 4.76 (s, 1 H), 5.75 (s, 1 H), 7.08-7.38 (m, 10 H); 13C
NMR (75 MHz, CDCl3) δ 20.44 (q), 22.23 (q), 37.81 (t), 114.77
(t), 125.55 (d), 126.50 (d), 127.34 (d), 128.00 (d), 128.27 (d),
128.71 (d), 130.27 (s), 133.37 (s), 140.00 (s), 140.56 (s), 148.61
(s); IR (neat) 3024, 2905, 1496, 1456, 1377, 1308, 1074, 1031,
908, 782, 728, 702 cm-1; HRMS calcd for C19H20 248.1565,
found 248.1564.
1-(1-Ben zyl-2-m et h yl-1-p r op en yl)-2-m et h oxyb en zen e
(4b). H NMR (300 MHz, CDCl3) δ 1.54 (s, 3 H), 1.92 (s, 3 H),
1
3.55 (d, J ) 13.9 Hz, 1 H), 3.73 (s, 3 H), 3.84 (d, J ) 13.9 Hz,
1 H), 6.73-6.84 (m, 3 H), 7.01-7.19 (m, 6 H); 13C NMR (75
MHz, CDCl3) δ 20.48 (q), 22.22 (q), 39.22 (t), 55.38 (q), 110.72
(d), 120.00 (d), 125.33 (d), 127.38 (d), 127.84 (d), 128.66 (d),
129.95 (s), 130.51 (s), 131.20 (d), 132.06 (s), 140.77 (s), 156.59
(s); IR (neat) 2906, 2830, 1600, 1575, 1488, 1459, 1243, 1117,
1056, 1034, 759, 709 cm-1; HRMS calcd for C18H20O 252.1514,
found 252.1511.
1-(1-Ben zyl-2-m et h yl-1-p r op en yl)-3-m et h oxyb en zen e
(4c). H NMR (300 MHz, CDCl3) δ 1.62 (s, 3 H), 1.91 (s, 3 H),
3.69 (s, 3 H), 3.70 (s, 2 H), 6.50-6.73 (m, 3H), 7.06-7.22 (m,
6 H); 13C NMR (75 MHz, CDCl3) δ 20.78 (q), 22.31 (q), 40.40
(t), 55.04 (q), 111.30 (d), 114.68 (d), 121.57 (d), 125.62 (d),
127.19 (s), 128.11 (d), 128.52 (d), 128.70 (d), 129.54 (s), 133.40
1-[2-(4-Meth oxyph en yl)-3-m eth yl-2-bu ten yl]-3-n itr oben -
1
zen e (4q). H NMR (300 MHz, CDCl3) δ 1.66 (s, 3 H), 1.92 (s,
3 H), 3.74 (s, 3 H), 3.79 (s, 2 H), 6.75 (dd, J 1 ) 2.4 Hz, J 2 ) 9.8
Hz, 2 H), 6.89 (dd, J 1 ) 2.4 Hz, J 2 ) 9.8 Hz, 2 H), 7.30-7.35
(m, 2 H), 7.92-8.01 (m, 2 H); 13C NMR (75 MHz, CDCl3) δ
20.83 (q), 22.28 (q), 40.12 (t), 55.13 (q), 113.46 (d), 120.90 (d),
123.30 (d), 128.87 (d), 129.98 (d), 130.72 (s), 131.81 (s), 134.76
(d), 135.06 (s), 142.65 (s), 148.30 (s), 157.93 (s); HRMS calcd
for C18H19NO3 297.1365, found 297.1363.
1
(19) Perrin, D. D.; Armarego, W. L. F. In Purification of Laboratory
Chemicals, 3rd ed.; Pergamon Press: New York, 1988.
(20) Heck, R. F. Palladium Reagents in Organic Syntheses; Academic
Press: New York, 1978.
(21) Takahashi, Y.; Ito, T.; Sakai, S.; Ishii, Y. J . Chem. Soc., Chem.
Commun. 1970, 1065-1066.
(22) Pasto, D. J .; Warren, S. E.; Morrison, M. A. J . Org. Chem. 1981,
46, 2837-2841.
(23) Brandsma, L.; Verkruijisse, H. D. Synthesis of Acetylenes,
Allenes and Cumulenes; Elsevier: New York, 1981.
(24) Piers, E.; Grierson, J . R.; Lau, C. K.; Nagakura, I. Can. J . Chem.
1982, 60, 210-223.
4-[2-(4-Meth oxyp h en yl)-3-m eth yl-2-bu ten yl]ben za ld e-
h yd e (4v). 1H NMR (300 MHz, CDCl3) δ 1.63 (s, 3 H), 1.90 (s,
3 H), 3.74 (s, 3 H), 3.76 (s, 2 H), 6.74 (d, J ) 7.5 Hz, 2 H), 6.87
(d, J ) 7.5 Hz, 2 H), 7.20 (d, J ) 8.0 Hz, 2 H), 7.69 (d, J ) 8.0
Hz, 2 H), 9.91 (s, 1 H); 13C NMR (75 MHz, CDCl3) δ 20.87 (q),
22.29 (q), 40.86 (t), 55.12 (q), 113.35 (d), 129.16 (d), 129.74 (d),
129.96 (d), 130.23 (s), 132.07 (s), 135.47 (s), 148.15 (s), 157.84
(s), 167.43 (s), 192.02 (d); IR (neat) 3013, 2970, 1698, 1604,
1509, 1244, 1016, 938, 857 cm-1; HRMS calcd for C19H20O2
280.1463, found 280.1463.

Pd-Catalyzed Three-Component Assembling
J . Org. Chem., Vol. 67, No. 1, 2002 105
1-[(Z)-1-Ben zyl-2-cyclop en t yl-1-et h en yl]-4-m et h oxy-
ben zen e (Z-7a ). H NMR (400 MHz, CDCl3) δ 1.19-1.76 (m,
(s), 159.49 (s), 162.72 (s); IR (neat) 2945, 2846, 1605, 1509,
1465, 1291, 1242, 1179, 1156, 1035, 827, 505 cm-1; HRMS calcd
for C20H23FO 298.1733, found 298.1734.
1
8 H), 2.37-2.43 (m, 1 H), 3.58 (s, 2 H), 3.75 (s, 3 H), 5.38 (d,
J ) 10.0 Hz, 1 H), 6.75-7.59 (m, 9 H); 13C NMR (75 MHz,
CDCl3) δ 25.50 (t), 34.15 (t), 39.68 (d), 45.73 (t), 55.10 (d),
113.21 (d), 114.19 (d), 125.76 (d), 126.72 (d), 128.13 (s), 128.94
(d), 129.60 (d), 133.57 (s), 137.73 (s), 140.15 (s), 158.02 (s); IR
(neat) 2952, 2858, 1607, 1513, 1459, 1294, 1274, 1182, 1038,
839, 767, 701 cm-1; HRMS calcd for C21H24O 292.1841, found
292.1845.
(Z)-1,2-Dip h en yl-2-h ep ten e (Z-7i). 1H NMR (400 MHz,
CDCl3) δ 0.82 (t, J ) 7.0 Hz, 3 H), 1.22-1.33 (m, 4 H), 1.94-
1.99 (m, 2 H), 3.63 (s, 2 H), 5.48 (t, J ) 7.6 Hz, 1 H), 7.04-
7.27 (m, 10 H); 13C NMR (100 MHz, CDCl3) δ 13.62 (q), 21.96
(t), 28.37 (t), 31.91 (t), 45.35 (t), 125.52 (d), 126.03 (d), 127.52
(d), 127.78 (d), 128.21 (d), 128.72 (d), 129.27 (d), 139.50 (s),
139.61 (s), 140.74 (s); IR (neat) 3026, 2957, 2862, 1729, 1600,
1493, 1452, 1276, 1072, 774, 699 cm-1; GC-EIMS m/z (rel
intensity) 250 (M+, 100), 193 (43), 179 (18), 159 (22), 129 (27),
117 (62); HRMS calcd for C19H22 250.1716, found 250.1727.
(E)-1,2-Dip h en yl-2-h ep ten e (E-7i). 1H NMR (400 MHz,
CDCl3) δ 0.90 (t, J ) 7.0 Hz, 3 H), 1.35-1.47 (m, 4 H), 2.24 (q,
J ) 7.2 Hz, 2 H), 3.87 (s, 2 H), 5.98 (t, J ) 6.8 Hz, 1 H), 7.12-
7.33 (m, 10 H); 13C NMR (100 MHz, CDCl3) δ 13.66 (q), 22.15
(t), 28.34 (t), 31.54 (t), 35.37 (t), 125.41 (d), 125.88 (d), 126.17
(d), 127.81 (d), 127.99 (d), 130.98 (d), 136.77 (s), 139.61 (s),
142.67 (s); IR (neat) 3059, 3025, 2956, 2925, 2862, 1600, 1493,
1451, 1378, 1074, 1030, 753, 722, 696 cm-1; GC-EIMS m/z (rel
intensity) 250 (M+, 23), 249 (M+-1, 100), 192 (37), 172 (21),
158 (38), 129 (47), 105 (22); HRMS calcd for C19H22 250.1716,
found 250.1712.
1-[(E)-1-Ben zyl-2-cyclop en t yl-1-et h en yl]-4-m et h oxy-
1
ben zen e (E-7a ). H NMR (400 MHz, CDCl3) δ 1.25-1.90 (m,
8 H), 2.72-2.83 (m, 1 H), 3.74 (s, 3 H), 3.86 (s, 2 H), 5.82 (d,
J ) 9.6 Hz, 1 H), 6.74 (d, J ) 6.8 Hz, 2 H), 7.09-7.25 (m, 7
H); 13C NMR (75 MHz, CDCl3) δ 25.45 (t), 33.91 (t), 35.93 (t),
39.88 (d), 55.21 (q), 113.52 (d), 125.72 (d), 127.25 (d), 128.18
(d), 128.30 (d), 134.87 (s), 135.13 (d), 135.45 (s), 140.24 (s),
158.34; IR (neat) 2942, 1605, 1511, 1245, 1165, 1020, 668 cm-1
HRMS calcd for C21H24O 292.1841, found 292.1845.
;
1-[(E)-1-Ben zyl-2-cycloh exyl-1-eth en yl]-4-m eth oxyben -
zen e (E-7d ). 1H NMR (300 MHz, CDCl3) δ 1.12-1.30 (m, 6
H), 1.62-1.71 (m, 4 H), 2.36-2.39 (m, 1 H), 3.74 (s, 3 H), 3.86
(s, 2 H), 5.74 (d, J ) 9.4 Hz, 1 H), 6.75 (d, J ) 6.7 Hz, 2 H),
7.10-7.27 (m, 7 H); 13C NMR (75 MHz, CDCl3) δ 25.91 (t),
26.04 (t), 33.36 (t), 35.76 (t), 37.89 (q), 55.18 (q), 113.49 (d),
125.70 (d), 127.30 (d), 128.19 (d), 128.29 (d), 134.48 (s), 135.33
(s), 135.55 (d), 140.19 (s), 158.35 (s); IR (neat) 2922, 2849, 1606,
1511, 1494, 1449, 1287, 1246, 1179, 1037, 969, 896, 832, 746,
700, 536 cm-1; HRMS calcd for C22H26O 306.1984, found
306.2001.
Ack n ow led gm en t. We thank the National Science
Council of the Republic of China (NSC 89-2119-M-007-
010) for support of this research.
1-[(E)-1-(4-F lu or ob en zyl)-3,3-d im et h yl-1-b u t en yl]-4-
m eth oxyben zen e (E-7f). H NMR (300 MHz, CDCl3) δ 1.20
(s, 9 H), 3.73 (s, 3 H), 3.98 (s, 2 H), 5.88 (s, 1 H), 6.68-7.20
(m, 8 H); 13C NMR (75 MHz, CDCl3) δ 31.43 (q), 33.07 (s), 34.99
(t), 55.18 (q), 113.45 (d), 114.78 (d), 115.06 (d), 127.59 (d),
129.71 (d), 129.82 (d), 135.56 (s), 136.63 (s), 140.66 (d), 158.34
Su p p or tin g In for m a tion Ava ila ble: Spectral data for
1
1
compounds 4e-j, 4p , 4r -u and 7b-c, 7e, 7g-h and H NMR
spectra of products 4a -v and 7a -i. This material is available
free of charge via the Internet at http://pubs.acs.org.
J O010637G