Propargylic and allenic carbocycle synthesis through palladium-catalyzed dearomatization reaction

Article abstract of DOI:10.1021/jo100211d

The dearomatization reaction of benzylic chlorides (1a?k), chloromethylnaphthalenes (1l?r), and naphthalene allyl chlorides (3a?d) with allenyltributyltin proceeded smoothly in the presence of Pd(PPh ₃)₄ catalyst at room temperature to give the corresponding propargylated and/or allenylated dearomatization products (5, 5′; 6, 6′; and 7, respectively) in high to fair yields. The reaction of 1a?k proceeded smoothly in the presence of TBAF, whereas it was not necessary to use TBAF as an additive in the reactions of 1l?k and 3a?d. These reactions provided a new and efficient method for the synthesis of propargylic and allenic carbocycles.

Full text of DOI:10.1021/jo100211d

pubs.acs.org/joc
Propargylic and Allenic Carbocycle Synthesis through
Palladium-Catalyzed Dearomatization Reaction
Bo Peng,† Xiujuan Feng,*,† Xin Zhang,‡ Sheng Zhang,† and Ming Bao*,†
†State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China, and
‡School Environmental Science &Technology, Dalian University of Technology, Dalian 116023, China
xiujuan.feng@163.com; mingbao@dlut.edu.cn
Received February 10, 2010
The dearomatization reaction of benzylic chlorides (1a-k), chloromethylnaphthalenes (1l-r), and
naphthalene allyl chlorides (3a-d) with allenyltributyltin proceeded smoothly in the presence of Pd(PPh3)4
catalyst at room temperature to give the corresponding propargylated and/or allenylated dearomatization
products (5, 50; 6, 60; and 7, respectively) in high to fair yields. The reaction of 1a-k proceeded smoothly in
the presence of TBAF, whereas it was not necessary to use TBAF as an additive in the reactions of 1l-k
and 3a-d. These reactions provided a new and efficient method for the synthesis of propargylic and allenic
carbocycles.
Introduction
Among the methods developed, the dearomatization reaction
of arenes has become a simple and useful tool for the prepara-
tion of alicyclic compounds since the aromatic compounds
are stable and widely available. Over the past four decades,
many types of dearomatization reaction, including oxida-
tion,1 reduction,2 photocycloaddition,3 [2,3]-σ-rearrangement,4
Development of efficient methods for the synthesis of
alicyclic compounds has attracted considerable attention
because the aliphatic carbocycle moieties frequently appear
in the molecules of natural products and bioactive compounds.
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DOI: 10.1021/jo100211d
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Published on Web 03/24/2010
J. Org. Chem. 2010, 75, 2619–2627 2619
2010 American Chemical Society

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JOCArticle
SCHEME 1. Allylative Dearomatization Reactions of Benzylic
Chlorides 1 and Naphthalene Allyl Chlorides 3 with Allyltributyl-
tin Catalyzed by Pd
SCHEME 2. Palladium-Catalyzed Dearomatization Reactions
of Benzylic Chlorides 1a-k, Chloromethylnaphthalenes 1l-r, and
Naphthalene Allyl Chlorides 3a-d with Allenyltributyltin
electrophilic addition,5 nucleophilic addition,6 and other
reactions,7 have been developed for breaking up the con-
jugated π-system. The complexation of the aromatic system
to transition metals leads to activation of arenes and thus
facilitates the electrophilic addition of [M(η2-arene)] (M =
Os, Re, Mo, and W) complexes and the nucleophilic addition
of [M(η6-arene)] (M = Cr, Mn, and Ru) complexes.
TABLE 1. Optimization of Pd-Catalyzed Dearomatization Reaction of
1a with Allenyltributyltina
In our previous study, we found benzylic chlorides 1 reacted
with allytributyltin in the presence of palladium catalyst to
give para allylated dearomatization products 2 (Scheme 1,
eq 1).8 Furthermore, we found the reaction of naphthalene
allyl chlorides 3 with allytributyltin in the presence of palla-
dium catalyst furnished ortho allylated products 4 (Scheme 1,
eq 2).9 In the two cases the corresponding Stille cross-coupling
products were not observed at all.
In this paper, we report that the reaction of benzylic
chlorides 1a-k and chloromethylnaphthalenes 1l-r with
allenyltributyltin gave the propargylic and allenic dearoma-
tization products 5, 50and 6, 60 (Scheme 2, eqs 3 and 4).
However, the reaction of naphthalene allyl chlorides 3a-d
entry
Pd source/ligand/solvent/additive
yield [%]b,c
1
2
3
4
5
6
7
8
Pd2(dba)3/PPh3/acetone/none
Pd(acac)2/PPh3/acetone/nones
Pd(OAc)2/PPh3/acetone/none
PdCl2(CH3CN)2/PPh3/acetone/none
Pd(PPh3)4/none/acetone/none
Pd(PPh3)4/none/CH3CN/none
Pd(PPh3)4/none/CH2Cl2/none
Pd(PPh3)4/none/THF/none
Pd(PPh3)4/none/ethyl ether/none
Pd(PPh3)4/none/CH2Cl2/KF
Pd(PPh3)4/none/CH2Cl2/TBAF
Pd(PPh3)4/none/CH2Cl2/DIPEA
11 (86/14)
16 (80/20)
17 (50/50)
NRd
35 (76/24)
24 (93/7)
36 (86/14)
7 (46/54)
NRd
9
10
11
12
66 (45/55)
82 (98/2)
23 (75/25)
(5) For reviews, see: (a) Keane, J. M.; Harman, W. D. Organometallics
2005, 24, 1786–1798. (b) Harman, W. D. Coord. Chem. Rev. 2004, 248, 853–
aReaction conditions: 0.5 mmol of 1a, 0.6 mmol of allenyltributyl-
tion, 5 mol % Pd, 10 mol % ligand, and 2.0 equiv of additive in 5 mL of
solvent under nitrogen atmosphere at room temperature for 12 h. bThe
yield was determined by 1H NMR using 4-bromobenzaldehyde as an
€
866. (c) Pape, A. R.; Kaliappan, K. P.; Kundig, E. P. Chem. Rev. 2000, 100,
2917–2940. See also: (d) Delafuente, D. A.; Myers, W. H.; Sabat, M.;
Harman, W. D. Organometallics 2005, 24, 1876–1885.
(6) Arenes were activated by electron-withdrawing groups; see: (a)
c
internal standard. The ratio of 5a to 5a0 is indicated in parentheses.
dNR: no reaction.
ꢀ
ꢀ
Ramallal, A. M.; Fernandez, I.; Ortiz, F. L.; Gonzalez, J. Chem.;Eur. J. 2005,
11, 3022-3031 and references therein. (b) Wang, Z.; Xi, Z. Synlett 2006, 1275–
1277. (c) Clayden, J.; Knowles, F. E.; Baldwin, L. R. J. Am. Chem. Soc. 2005,
127, 2412–2413. (d) Clayden, J.; Turnbull, R.; Helliwell, M.; Pinto, I. Chem.
Commun. 2004, 2430–2431. (e) Clayden, J.; Tumbull, R.; Pinto, I. Org. Lett.
2004, 6, 609–611. (f) Clayden, J.; Kenworthy, M. N.; Helliwell, M. Org. Lett.
with allenyltributyltin offered only propargylic dearomati-
zation products 7 (Scheme 2, eq 5).
ꢀ
2003, 5, 831–834. (g) Barluenga, J.; Nandy, S. K.; Laxmi, Y. R. S.; Suarez,
Results and Discussion
ꢀ
J. R.; Merino, I.; Florez, J.; García-Granda, S.; Montejo-Bernardo, J. Chem.;
Eur. J. 2003, 9, 5725–5736. Arenes were activated by complexation to transition
metals; see: (h) Zhou, L.; Wu, L. Z.; Zhang, L. P.; Tung, C. H. Organometallics
2006, 25, 1707–1711. (i) K€undig, E. P.; Bellido, A.; Kaliappan, K. P.; Pape, A. R.;
Radix, S. Org. Biomol. Chem. 2006, 4, 342–351. (j) Pigge, F. C.; Coniglio, J. J.;
Dalvi, R. J. Am. Chem. Soc. 2006, 128, 3498–3499. (k) Pigge, F. C.; Coniglio,
J. J.; Rath, N. P. Org. Lett. 2003, 5, 2011–2014. . See also ref 6c.
(7) For organolanthanide-induced dearomatization, see: (a) Liu, R.;
Zhang, C.; Zhu, Z.; Luo, J.; Zhou, X.; Weng, L. Chem.;Eur. J. 2006, 12,
6940–6952. For radical addition, see: (b) Crich, D.; Sannigrahi, M. Tetra-
hedron 2002, 58, 3319–3322. (c) Boivin, J.; Yousfi, M.; Zard, S. Z. Tetra-
hedron Lett. 1997, 38, 5985–5988. For a dearomatization involving
naphthylborate anions, see: (d) Negishi, E.; Merrill, R. E. J. Chem. Soc.,
Chem. Commun. 1974, 860–861.
In our initial studies, we chosen the reaction of 4-methyl
benzylic chloride (1a) with allenyltributyltin as a model
reaction to screen the reaction conditions, and the results
are shown in Table 1. When the reaction of 1a with allenyl-
tributyltin was carried out under similar conditions as
employed in the allylative dearomatization of 1a with allyl-
tributyltin,8 a 86/14 mixture of 5a and 5a0 was obtained in
only 11% yield (entry 1). The use of Pd(acac)2, Pd(OAc)2,
and PdCl2(CH3CN)2 as Pd source, instead of Pd2(dba)3, did
not give the desired products in high yields (entries 2-4).
Slightly increased yield was obtained when the reaction was
performed in the presence of Pd(PPh3)4 as a catalyst in
(8) Bao, M.; Nakamura, H.; Yamamoto, Y. J. Am. Chem. Soc. 2001, 123,
759–760.
(9) Lu, S.; Xu, Z.; Bao, M.; Yamamoto, Y. Angew. Chem., Int. Ed. 2008,
47, 4366–4369.
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acetone, CH3CN, or CH2Cl2 (entries 5-7, 35%, 24%,
and 36%, respectively). However, the yield was decreased
to 7% and 0%, when the solvent was changed to tetrahydro-
furan (THF) or diethyl ether (entries 8 and 9). It was thought
that the lower yields of the desired products 5a and 5a0 would
be due to lower reactivity of allenyltributyltin. It has been
described that fluoride additives could be employed to activate
organotin reagents.10 Indeed, the reaction yield was dramati-
cally increased when potassium fluoride (KF) or tetrabuty-
lammonium fluoride (TBAF) was added in the reaction
mixture (entries 10 and 11, 66% and 82%, respectively).
However, the use of N,N-diisopropylethylamine (DIPEA)11
as an additive did not improve the yield (entry 13, 23%). Under
the above conditions examined, 5a was usually obtained as a
major product. The highest ratio of 5a to 5a0 was 98/2, as
shown in entry 11. Therefore, in the subsequent studies, the
reactions of benzylic chlorides 1a-k with allenyltributyltin
were performed in the presence of Pd(PPh3)4 as a catalyst using
TBAF as an additive in CH2Cl2.
reaction time (48 h); perhaps this is due to the steric hin-
drance of a tert-butyl group at the reaction site. Reaction of
substrate 1j having two benzene rings occurred selectively on
the electron-richer benzene ring to give propargylic and
allenic products 5j and 5j0 in total 63% yield with a ratio of
62/28 (entry 10). The propargylic and allenic products 5k and
5k0 were obtained in total 48% yield with a ratio of 83/17
from the reaction of substrate 1k, which has a structure
similar to 1j. The desired reaction occurred selectively on the
sterically less hindered benzene ring (entry 11).
We then examined the reactions of chloromethylnaphtha-
lene derivatives 1l-r with allenyltributyltin to expand the scope
of this type dearomatization reaction, and the results are shown
in Table 3. Comparison of the result of entry 1 (85% yield with
a ratio of 20/80) with that of entry 2 (89% yield with a ratio of
18/82) leads to a conclusion that the reaction of chloromethyl
naphthalene 1l did not need TBAF to activate allenyltributyl-
tin. Therefore, in the following examples, we carried out the
reactions of 1m-r in the absence of TBAF. Only allenic
product 6m0 could be isolated in 89% yield from the reaction
of 1m (entry 3). When a mixture of substrate 1n, bearing a
hydroxymethyl group on the para position of the chloromethyl
group, and allenyltributyltin was treated as usual for 12 h, the
expected product was not obtained and the starting materials
were decomposed (entry 4). As expected, when the hydroxy-
methyl group of 1n was protected by tert-butyldimethylsilyl
group (TBS), the desired reaction proceeded to give pro-
pargylic and allenic products 6o and 6o0 in total 94% yield
with a ratio of 39/61 (entry 5). We then examined deprotection
reaction of the product 6o by using TBAF as a deprotection
reagent, and the desired product 9 was obtained in 76% yield
(Scheme 3). However, under the same deprotection reaction
conditions, 6o0 underwent polymerization reaction. The reac-
tion of substrate 1p bearing a phenyl group on the para position
of the chloromethyl group gave a propargylic product 6p as a
sole isolated product in 65% yield (entry 6). Allenyl group
could be introduced into 9-(chloromethyl)anthracene (1q) to
offer allenic product 6q0 in an excellent yield (entry 7, 96%).
Finally, we examined the reaction of substrate 1r, which had an
ester as a leaving group (OCOR) and a hydrogen atom beta to
the OCOR group, and found that this reaction proceeded more
slowly than those of 1l-q to provide propargylic product 6r in
71% yield,12 without the formation of any β-hydride elimina-
tion product (entry 8).13
The reactions of various benzylic chlorides 1a-k with
allenyltributyltin were performed under optimized condi-
tions, and the results are summarized in Table 2. After the
reaction of 1a was completed, only the major product 5a
could be isolated in 71% yield (entry 1). Although the
1
formation of 5a0 was detected by H NMR analysis of a
product mixture in entry 11, Table 1, 5a0 was not isolated; it
was considered that the formation of 5a0 was too small.
Products 5b and 5b0 were obtained in total 67% yield with a
ratio of 75/25 from the reaction of 1b (entry 2). The sub-
strates 1c and 1d having one or two methoxy groups on
aromatic ring also smoothly underwent the dearoamtization
reaction to offer the propargylic compounds 5c and 5d in
82% and 78% yield, respectively (entries 3 and 4). The
reaction of 4-chlorobenzyl chloride (1e) gave product 5e
bearing two propargyl groups on the para position of the
exocyclic methylene group in 92% yield (entry 5). It was
considered that the product 5e would be formed through the
second propargylation of the intermediate 8, which was
given by the first propargylation, as ordinarily observed.
However, the substrate 1f possessing two chlorine atoms on
the aromatic ring could not undergo the dearomatization
reaction (entry 6); perhaps this is due to the fact that the
electron-deficient benzene ring of 1f could not generate a
stable π-benzylpalladium chloride intermediate.8 A similar
result was observed when 4-formylbenzyl chloride (1g) was
treated with allenyltributyltin (entry 7). Interestingly, an
excellent yield was obtained when the formyl group of 1g
was protected by ethylene glycol (entry 8, 92%). A lower
yield was obtained from the reaction of 4-tert-butylbenzyl
chloride (1i) with allenyltributyltin even under the prolonged
A plausible mechanism for the dearomatization reactions
of benzylic chlorides and chloromethylnaphthalenes is
shown in Scheme 4. The oxidative addition of 1 to a Pd0
(12) The connection and configuration of products 6r and 7a were
obtained from 1H-1H COSY and NOESY spectrum.
(10) Fluoride additives have been utilized to activate organotin reagents.
See: (a) Mee, S. P. H.; Lee, V.; Baldwin, J. E. Chem.;Eur. J. 2005, 11,
3294-3308 and references therein. TBAF was also employed as an additive to
activate organosilane reagents. See: (b) Fernandes, R. A.; Yamamoto, Y. J. Org.
Chem. 2004, 69, 735–738. (c) Nakamura, K.; Nakamura, H.; Yamamoto, Y.
J. Org. Chem. 1999, 64, 2614–2615.
(11) It has been reported that organotin reagents could be activated by
intramolecular coordination of nitrogen atom to Sn(IV). See: (a) Vedejs, E.;
Haight, A. R.; Moss, W. O. J. Am. Chem. Soc. 1992, 114, 6556–6558.
(b) Brown, J. M.; Pearson, M.; Jastrzebski, J. T. B. H.; van Koten, G.
J. Chem. Soc., Chem. Commun. 1992, 1440–1441. (c) Jensen, M. S.; Yang, C.;
Hsiao, Y.; Rivera, N.; Wells, K. M.; Chung, J. Y. L.; Yasuda, N.; Hughes,
D. L.; Reider, P. J. Org. Lett. 2000, 2, 1081–1084. (d) Sebahar, H. L.;
Yoshida, K.; Hegedus, L. S. J. Org. Chem. 2002, 67, 3788–3795.
(13) In the Stille cross-coupling reaction of C(sp3)-X electrophiles, the β
hydride elimination often gave alkenes in preference to coupling products;
ꢀ
see: (a) Cardenas, D. J. Angew. Chem. 2003, 115, 398-401; Angew. Chem.,
Int. Ed. 2003, 42, 384-387. (b) Luh, T. Y.; Leung, M. k.; Wong, K. T. Chem. Rev.
2000, 100, 3187–3204.
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TABLE 2. Dearomatization Reaction of Benzylic Chlorides 1a-k with Allenyltributyltina
aA mixture of benzylic chloride (0.5 mmol), allenyltributyltion (0.6 mmol), Pd(PPh3)4 (5 mol %), and TBAF (1.0 mmol) in dichloromethane (5 mL)
was stirred at room temperature under nitrogen atmosphere for the period indicated in the table. bThe ratio of 5 to 50 is indicated in parentheses. cNR: no
reaction. The starting material, benzylic chloride, was recovered, and the allenyltributyltin was decomposed.
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TABLE 3. Dearomatization Reaction of Chloromethylnaphthalene Derivatives 1l-1s with Allenyltributyltina
aA mixture of chloromethylnaphthalene (0.5 mmol), allenyltributyltion (0.6 mmol), and Pd(PPh3)4 (5 mol %) in dichloromethane (5 mL) was stirred
at room temperature under nitrogen atmosphere for the period indicated in the table. bThe ratio of 6 to 60 is indicated in parentheses. cOne millimole of
TBAF was used as an additive.
species would produce the η3-allylpalladium chloride inter-
mediate A, which would react with allenyltributylstannane
to generate a η3-allyl-η3-propargylpalladium intermediate B
upon ligand exchange. The isomerization of B would occur
to give (η3-allyl)allenylpalladium intermediate C and/or
(η3-allyl)propargylpalladium intermediate D, which could
undergo reductive elimination to form the dearomatization
products 5, 6 and 50, 60, respectively, and regenerate Pd0
catalyst.14
We finally investigated the reactions of naphthalene
allyl chlorides 3a-d with allenyltributyltin, and the results
are summarized in Table 4. Similar to the chloromethyl
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SCHEME 3. Deprotection Reaction of Propargylic Product 6o
TABLE 4. Dearomatization Reaction of Naphthalene Allyl Chlorides
3a-d with Allenyltributyltina
naphthalene derivatives 1l-r, naphthalene allyl chlorides
3a-d also exhibited high reactivities in the dearomatization
reaction. All of the reactions of 3a-d with allenyltributyltin
proceeded smoothly in the absence of TBAF activator to
provide propargylic products in satisfactory yields. For
example, the reaction of substrate 3a completed within 4 h
to give propargylic product 7a in 93% yield (entry 1).12 The
reaction of substrate 3b bearing a bromine atom in the para
position of the chloroallyl group gave the desired product 7b
in 75% yield. A bromine atom remained on the product 7b,
suggesting that further manipulation may produce a useful
compound. The substrate 3c bearing a methyl group, an
electron-donating group, underwent the dearomatization,
but the reaction progress was slightly slow compared to the
reactions of 3a and 3b, and the product 7c was obtained in a
good yield (entry 3, 84%). Obviously, the substrate 3d
exhibited a reactivity lower than that of substrates 3a-c.
Product 7d was obtained in 62% yield after 24 h (entry 4).
A plausible mechanism for the dearomatization reaction
of naphthalene allyl chlorides is shown in Scheme 5. Naph-
thalene allyl chloride 3a reacts with Pd0 to produce the η3-
allylpalladium chloride intermediate D, which would react
with allenyltributylstannane to generate a η3-allyl-η3-pro-
pargylpalladium intermediate E upon ligand exchange. The
isomerization of E would give η3-allyl-η1-allenylpalladium
intermediate F, which could undergo reductive elimination
to form the dearomatization product 7a and regenerate Pd0
catalyst.14
aA mixture of naphthalene allyl chloride (0.5 mmol), allenyltributyl-
tion (0.6 mmol), and Pd(PPh3)4 (5 mol %) in dichloromethane (5 mL)
was stirred at room temperature under nitrogen atmosphere for the
period indicated in the table.
Conclusions
In conclusion, we have expanded the scope of palladium-
catalyzed allylative dearomatization reaction to the propargy-
lative and allenylative dearomatization of benzylic chlorides,
chloromethyl naphthalenes, and naphthalene allyl chlorides by
using allenyltributyltin as a reaction partner, instead of allyl-
tributyltin. The reactivity of benzylic chlorides with allenyltri-
butyltin was different from those of benzylic chlorides with
allyltributytin previously reported; the former needed an
activator (TBAF) to promote the reaction, producing the
propargylic isomer as the major product. However, chloro-
methyl naphthalenes and naphthalene allyl chlorides could
react with allenyltributyltin in the absence of TBAF, which
might be due to higher reactivities of them than benzylic
chlorides. All of the reactions of chloromethylnaphthalene
derivatives, except for the reactions of 1p and 1r, afforded
allenic derivatives as major products or as a sole isolated
product. In the reactions of naphthalene allyl chlorides, pro-
pargylic products were isolated exclusively, and the reason why
the allenic products could not be formed is not clear at present.
We believe that these reactions reported herein provided a new
and efficient method for the synthesis of propargylic and
allenic carbocycles.
(14) This proposed mechanism is primarily based on the analogy of the
allylative dearomatization (see ref 8). After our allylative deaaromatization
paper appeared in 2001, Ariafared and Lin reported DFT studies on the
mechanism of the allylative dearomatization, and the computational result
suggested that an alternative mechanism would be more appropriate than
our originally proposed mechanism (see: Ariafard, A.; Lin, Z. J. Am. Chem.
Soc. 2006, 128, 13010–13016. ); σ-allyl-hapto-3-exo-benzyl palladium is a key
intermediate, in which a 1,3-allyl migration from palladium to the C-4
position of the six-membered ring takes place to lead to the dearomatization
product. We believe this is a plausible and interesting mechanism. We are not
sure whether a similar 1,3-rearrangement easily takes place in the case of the
allenyl-system. It is an interesting point whether such 1,3-rearrangement
takes place equally or more easily in the σ-allenyl than in the σ-allyl
palladium intermediate. Accordingly, there is possibility that a mechanism
proposed by Ariafared and Lin may be operative in the present case.
Experimental Section
Representative Procedure for the Palladium-Catalyzed Dear-
omatization Reaction of 1a-k with Allenyltributyltin. To a
mixture of Pd(PPh3)4 (28.9 mg, 0.025 mmol) and TBAF (261.5
mg, 1.0 mmol) in dichloromethane (3 mL) at room temperature
were added benzylic chloride 1a (70.0 mmg, 0.5 mmol) and
allenyltributyltin (197.5 mg, 0.6 mmol), and then the mixture
was stirred under a N2 atmosphere. The reaction progress was
monitored by TLC. After the allenyltributyltin was consumed,
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SCHEME 4. Proposed Mechanism for the Dearomatization Reaction of Benzylic Chlorides with Allenylributyltin
(neat) 3295, 2968, 2928, 1694, 1669, 1586, 1382, 798, 657 cm-1
;
HRMS (EI) calcd for C12H14: 158.1096 [M]þ; found: 158.1101.
1,6-Dimethyl-3-methylene-6-(propa-1,2-dienyl)cyclohexa-1,4-
diene (5b0). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 6.14 (d,
J = 9.6 Hz, 1H), 6.00 (s, 1H), 5.62 (d, J = 9.6 Hz, 1H), 5.05 (t,
J = 6.4 Hz, 1H), 4.82 (d, J = 6.4 Hz, 2H), 4.74 (d, J = 8.8 Hz,
2H), 1.80 (s, 3H), 1.23 (s, 3H); 13C NMR (100 MHz, CDCl3) δ
207.2, 142.0, 138.4, 137.3, 124.9, 124.0, 110.2, 97.4, 77.4, 41.6,
24.8, 18.9; IR (neat) 2967, 2925, 1951, 1667, 1586, 1375, 876, 796,
652 cm-1; HRMS (EI) calcd for C9H11: 119.0861 [M - C3H3]þ;
found: 119.0863.
SCHEME 5. Proposed Mechanism for the Dearomatization
Reaction of Naphthalene Allyl Chlorides with Allenylributyltin
3-Methoxy-6-methylene-3-(prop-2-ynyl)cyclohexa-1,4-diene
(5c). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 6.52 (d, J =
9.6 Hz, 2H), 5.75 (d, J = 9.6 Hz, 2H), 5.15 (s, 2H), 3.09 (s, 3H),
2.51 (d, J = 2.4 Hz, 2H), 2.02 (d, J = 2.4 Hz, 1H); 13C NMR
(100 MHz, CDCl3) δ 136.6, 131.1, 130.2, 118.2, 79.6, 73.8, 70.5,
51.9, 31.9; IR (neat) 3298, 2933, 2121, 1940, 1729, 1587, 1245,
1089, 1065, 685 cm-1; HRMS (EI) calcd for C11H12O: 160.0888
[M]þ; found: 160.0882.
1,6-Dimethoxy-3-methylene-6-(prop-2-ynyl)cyclohexa-1,4-
diene (5d). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.46 (d,
J = 7.6 Hz, 1H), 6.89 (d, J = 7.6 Hz, 1H), 6.85 (s, 1H), 4.44 (s,
2H), 3.84 (s, 3H), 3.55 (d, J = 2.8 Hz, 2H), 3.38 (s, 3H), 2.16 (t,
J = 2.8 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 157.0, 138.4,
128.8, 124.1, 119.9, 109.4, 82.1, 74.8, 70.4, 58.2, 55.5, 19.2; IR
(neat) 3292, 2923, 2119,1940, 1719, 1586, 1463, 1262, 1192, 1154,
817, 639 cm-1; HRMS (EI) calcd for C12H14O2: 190.0994 [M]þ;
found: 190.0999.
6-Methylene-3,3-di(prop-2-ynyl)cyclohexa-1,4-diene (5e). Color-
less oil; 1H NMR (400 MHz, CDCl3) δ 6.32 (d, J = 10.0 Hz, 2H),
5.84 (d, J= 1.0 Hz, 2H), 4.93 (s, 2H), 2.45 (d, J= 2.8 Hz, 4H), 2.05
(t, J = 2.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ 137.4, 133.1,
128.3, 114.0, 80.2, 71.2, 41.1, 29.7; IR (neat) 3296, 2923, 2117, 1586,
1428, 1384, 945, 803, 636 cm-1; HRMS (EI) calcd for C13H12:
168.0939 [M]þ; found: 168.0941.
2-(4-Methylene-1-(prop-2-ynyl)cyclohexa-2,5-dienyl)-1,3-di-
oxolane (5h). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 6.43
(d, J = 10.0 Hz, 2H), 5.80 (d, J = 10.0 Hz, 2H), 4.95 (s, 2H), 4.90
(s, 1H), 3.97-3.85 (bm, 4H), 2.46 (d, J = 2.8 Hz, 2H), 1.97 (t,
J = 2.8 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 137.3, 129.75,
129.72, 114.3, 106.4, 80.3, 70.4, 65.5, 46.4, 26.0; IR (neat) 3399,
3291, 1665, 1383, 1145, 1079, 1051, 945, 809, 690 cm-1; HRMS
(EI) calcd for C10H9: 129.0704 [M - C3H5O2]þ; found: 129.0707.
3-tert-Butyl-6-methylene-3-(prop-2-ynyl)cyclohexa-1,4-diene
(5i). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 6.39 (d,
J = 10.0 Hz, 2H), 5.77 (d, J = 10.0 Hz, 2H), 4.87 (s, 2H),
2.42 (d, J = 2.8 Hz, 2H), 1.89 (t, J = 2.8 Hz, 1H), 0.92 (s, 9H);
the solvent was removed under a reduced pressure. The product
was filtered through a short basic alumina column with pentane
to remove palladium residue and then was purified with a basic
alumina column using pentane as eluent, giving propargylic
product 5a in 71% yield (51.1 mg) as a colorless liquid.
3-Methyl-6-methylene-3-(prop-2-ynyl)cyclohexa-1,4-diene
(5a). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 6.22 (d, J =
10.0 Hz, 2H), 5.76 (d, J = 10.0 Hz, 2H), 4.87 (s, 2H), 2.25 (d, J =
2.4 Hz, 2H), 2.03 (t, J = 2.4 Hz, 1H), 1.20 (s, 3H); 13C NMR (100
MHz, CDCl3) δ 137.5, 135.9, 126.5, 112.5, 80.5, 70.5, 38.4, 32.2,
27.0; IR (neat) 3295, 2924, 2044, 2025, 1652, 1506, 1456, 1280,
1083, 838, 636 cm-1; HRMS (EI) calcd for C11H12: 144.0939
[M]þ; found: 144.0946.
3-Methyl-6-methylene-3-(propa-1,2-dienyl)cyclohexa-1,4-
diene (5a0). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 6.18 (d,
J = 8.0 Hz, 2H), 5.69 (d, J = 8.0 Hz, 2H), 5.09 (t, J = 8.0 Hz,
1H), 4.68 (s, 2H), 4.81 (d, J = 8.0 Hz, 2H), 1.21 (s, 3H); 13C
NMR (100 MHz, CDCl3) δ 206.7, 137.3, 136.1, 125.3, 112.4,
98.1, 77.6, 38.8, 27.7; IR (neat) 2965, 1950, 1663, 1584, 1384,
1061, 870, 657 cm-1; HRMS (EI) calcd for C10H9: 129.0704
[M - CH3]þ; found: 129.0708.
1,6-Dimethyl-3-methylene-6-(prop-2-ynyl)cyclohexa-1,4-
diene (5b). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 6.23 (d,
J = 12.0 Hz, 1H), 6.06 (s, 1H), 5.74 (d, J = 12.0 Hz, 1H), 4.76 (d,
J = 8.0 Hz, 2H), 2.36 (d, J = 8.0 Hz, 2H), 1.97 (s, 1H), 1.82 (s,
3H), 1.21 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 141.0, 138.5,
136.7, 126.3, 125.3, 110.5, 81.1, 70.1, 41.3, 30.2, 25.8, 18.5; IR
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13C NMR (100 MHz, CDCl3) δ 137.8, 132.9, 129.1, 112.7, 82.4,
69.9, 48.2, 37.8, 26.1, 25.8; IR (neat) 3308, 2967, 1664, 1584,
1367, 1193, 871, 629 cm-1; HRMS (EI) calcd for C14H18:
186.1409 [M]þ; found: 186.1417.
7.76-7.74 (m, 1H), 7.42-7.39 (m, 1H), 7.31-7.27 (m, 1H),
7.24-7.20 (m, 1H), 6.36 (d, J = 10.0 Hz, 1H), 5.74 (d, J = 10.0
Hz, 1H), 5.68 (s, 1H), 5.30 (t, J = 6.8 Hz, 1H), 5.04 (s, 1H),
4.91-4.87 (m, 2H), 1.45 (s, 3H); 13C NMR (100 MHz, CDCl3) δ
206.7, 141.8, 137.2, 135.4, 130.4, 128.14, 128.12, 126.4, 126.3,
123.1. 109.5, 99.7, 78.0, 40.4, 29.4; IR (neat) 2925, 1952, 1695,
1590, 1455, 870, 775, 755 cm-1; HRMS (EI) calcd for C15H14:
194.1096 [M]þ; found: 194.1100.
Methyl 4-Methylene-1-(propa-1,2-dienyl)-1,4-dihydronaphthalene-
1-carboxylate (6m0). Colorless oil; 1H NMR (400 MHz, CDCl3)
δ 7.79-7.77 (m, 1H), 7.42-7.39 (m, 1H), 7.30-7.27 (m, 2H),
6.55 (d, J = 10.0 Hz, 1H), 5.91 (d, J = 8.0 Hz, 1H), 5.86 (d, J =
6.8 Hz, 1H), 5.77 (s, 1H), 5.16 (s, 1H), 4.82-4.71 (m, 2H),
3.65 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 207.7, 173.1, 136.3,
134.9, 130.7, 128.9, 128.7, 128.3, 127.6. 127.3, 123.5, 111.7,
96.4, 78.8, 53.1, 52.4; IR (neat) 3063, 2950, 1956, 1731, 1592,
1482, 1229, 772 cm-1; HRMS (EI) calcd for C16H14O2: 238.0994
[M]þ; found: 238.1002.
tert-Butyldimethyl((4-methylene-1-(prop-2-ynyl)-1,4-dihydro-
naphthalen-1-yl)methoxy)silane (6o). Colorless oil; 1H NMR
(400 MHz, CDCl3) δ 7.83 (d, J = 8.4 Hz, 1H), 7.53 (d, J =
7.2 Hz, 1H), 7.35-7.29 (m, 2H), 6.60 (d, J = 10.0 Hz, 1H), 6.01
(d, J = 10.0 Hz, 1H), 5.74 (s, 1H), 5.11 (s, 1H), 3.71-3.65 (m,
2H), 2.90-2.70 (bm, 2H), 1.90 (s, 1H), 0.90 (s, 9H), 0.00 (s, 6H);
13C NMR (100 MHz, CDCl3) δ 137.7, 137.6, 132.1, 131.4, 129.6,
127.6, 127.0, 126.7, 123.2, 109.8, 81.5, 70.1, 70.0, 45.3, 27.7, 25.8,
18.2, -5.5, -5.6; IR (neat) 3310, 2953, 1471, 1388, 1254, 1100,
776 cm-1; HRMS (EI) calcd for C21H28OSi: 324.1909 [M]þ;
found: 324.1906.
tert-Butyldimethyl((4-methylene-1-(propa-1,2-dienyl)-1,4-di-
hydronaphthalen-1-yl)methoxy)-silane (6o0). Colorless oil; 1H
NMR (400 MHz, CDCl3) δ 7.75 (d, J = 7.6 Hz, 1H), 7.41 (d,
J = 7.6 Hz, 1H), 7.29-7.21 (m, 2H), 6.48 (d, J = 10.0 Hz, 1H),
5.87 (d, J = 10.0 Hz, 1H), 5.67 (s, 1H), 5.51 (t, J = 6.4 Hz, 1H),
5.04 (s, 1H), 4.82-4.74 (m, 2H), 3.73-3.66 (m, 2H), 0.78 (s, 9H),
-0.09 (s, 3H), -0.15 (s, 3H); 13C NMR (100 MHz, CDCl3) δ
207.6, 138.3, 137.5, 131.9, 131.8, 128.4, 128.3, 127.6, 126.5,
122.9. 109.5, 95.7, 77.3, 71.1, 46.3, 25.7, 18.1, -5.5, -5.6; IR
(neat) 2953, 1593, 1471, 1387, 1255, 1104, 839, 775 cm-1; HRMS
(EI) calcd for C21H28OSi: 324.1909 [M]þ; found: 324.1898.
4-Methylene-1-phenyl-1-(prop-2-ynyl)-1,4-dihydronaphtha-
lene (6p). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.79 (d,
J = 7.6 Hz, 1H), 7.30-7.25 (m, 4H), 721-7.12 (bm, 3H), 6.96
(d, J = 8.0 Hz, 1H), 6.56 (d, J = 9.6 Hz, 1H), 5.96 (d, J = 10.0
Hz, 1H), 5.77 (s, 1H), 5.15 (s, 1H), 3.16-2.95 (bm, 2H), 1.90 (t,
J = 2.4 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 145.7, 140.8,
137.1, 134.0, 131.2, 129.0, 128.3, 128.2, 127.6. 127.5, 126.5,
126.4, 123.1, 110.4, 80.0, 71.2, 48.3, 31.5; IR (neat) 3291, 2924,
1591, 1493, 1035, 910, 753, 698 cm-1; HRMS (EI) calcd for
C20H16: 256.1252 [M]þ; found: 256.1253.
1-Chloro-4-((4-methyl-4-(prop-2-ynyl)cyclohexa-2,5-dienyl-
idene)methyl)benzene (5j). Colorless oil; 1H NMR (CDCl3, 400
MHz) δ 7.30-7.24 (m, 4H), 6.72 (d, J = 10.4 Hz, 1H), 6.26 (dd,
J = 1.6, 9.2 Hz, 1H), 6.22 (s, 1H), 5.90 (d, J = 10.0 Hz,1H), 5.82
(dd, J = 1.6, 9.2 Hz, 1H), 2.30 (d, J = 2.8 Hz, 2H), 2.04 (t, J =
2.8 Hz, 1H), 1.25(s, 3H); 13C NMR (CDCl3, 100 MHz) δ 138.3,
135.7, 135.6, 132.4, 131.4, 130.2, 128.47, 128.72, 125.6, 121.8,
80.7, 70.6, 39.1, 32.2, 27.0; IR (neat) 3302, 2922, 1658, 1488,
1273,1013, 866, 796, 661 cm-1; HRMS (EI) calcd for C14H12Cl:
215.0628; [M - C3H3]þ; found: 215.0635.
1-Chloro-4-((4-methyl-4-(propa-1,2-dienyl)cyclohexa-2,5-
1
dienylidene)methyl)benzene (5j0). Colorless oil; H NMR (400
MHz, CDCl3) δ 7.30-7.23 (m, 4H), 6.68 (d, J = 10.0, 1H),
6.22-6.20 (m, 2H), 5.83 (d, J = 10.0, 1H), 5.75 (d, J = 10.0,
1H), 5.12 (t, J = 6.4, 1H), 4.83 (d, J = 6.4, 2H), 1.25 (s, 3H); 13
C
NMR (100 MHz, CDCl3) δ 206.7, 138.5, 135.9, 135.7, 132.4,
131.2, 130.2, 128.4, 127.4, 125.6, 120.6, 97.8, 77.4, 39.5, 27.7; IR
(neat) 2921, 1950, 1488, 1089, 1012, 847, 796, 657 cm-1; HRMS
(EI) calcd for C17H15Cl: 254.0862 [M]þ; found: 254.0869.
1-tert-Butyl-4-((4-methyl-4-(prop-2-ynyl)cyclohexa-2,5-dienyl-
1
idene)methyl)benzene (5k). Colorless oil; H NMR (400 MHz,
CDCl3) δ 7.36-7.34 (m, 2H), 7.28-7.25 (m, 2H), 6.82 (d,
J = 10.4, 1H), 6.28-6.25 (m, 2H), 5.86-5.83 (m, 1H), 5.79-
5.76 (m, 1H), 2.29 (d, J = 2.8, 2H), 2.03 (t, J = 2.8, 1H), 1.32 (s,
9H), 1.24 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 149.7, 137.3,
134.8, 134.3, 130.5, 128.8, 128.7, 127.1, 125.1, 122.3, 80.9, 70.5,
38.9, 34.5, 32.4, 31.3, 27.1; IR (neat) 3304, 3023, 2962, 1653,
1507, 1363, 1268, 1123, 796, 661 cm-1; HRMS (EI) calcd for
C21H24: 276.1878 [M]þ; found: 276.1880
1-tert-Butyl-4-((4-methyl-4-(propa-1,2-dienyl)cyclohexa-2,5-
1
dienylidene)methyl)benzene (5k0). Colorless oil; H NMR (400
MHz, CDCl3) δ 7.35-7.33 (m, 2H), 7.28-7.25 (m, 2H), 6.78 (d,
J = 10.0, 1H), 6.25 (s, 1H), 6.22 (d, J = 10.0, 1H), 5.77 (d, J =
10.0, 1H), 5.70 (d, J = 10.0, 1H), 5.12 (t, J = 8.4, 1H), 4.81 (d,
J = 8.4, 2H), 1.32 (s, 9H), 1.24 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ 206.7, 149.7, 137.5, 135.0, 134.3, 130.3, 128.7, 127.7,
127.0, 125.1, 121.2, 98.1, 77.6, 39.4, 34.5, 31.3, 27.8; IR (neat)
2962, 1950, 1362, 1268, 906, 845, 796 cm-1; HRMS (EI) calcd
for C21H24: 276.1878, found: 276.1885.
Representative Procedure for the Palladium-Catalyzed
Dearomatization Reaction of 1l-r and 3a-d with Allenyltributyltin.
To a solution of Pd(PPh3)4 (28.9 mg, 0.025 mmol) in dichloro-
methane (3 mL) at room temperature were added chloromethyl-
naphthalene 1l (95.3, 0.5 mmol) and allenyltributyltin (197.5 mg,
0.6 mmol), and then the mixture was stirred under a N2 atmo-
sphere. The reaction progress was monitored by TLC. After the
allenyltributyltin consumed, the solvent was removed under a
reduced pressure. The product was filtered through a short basic
alumina column with hexane to remove palladium residue and
then was purified with a basic alumina column using hexane as
eluent, giving propargylic and allenic products 6l and 6l0 in 17%
(16.4 mg) and 68% yield (66.7 mg), respectively.
1-Methyl-4-methylene-1-(prop-2-ynyl)-1,4-dihydronaphtha-
lene (6l). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.78-7.76
(m, 1H), 7.43-7.40 (m, 1H), 7.33-7.29 (m, 1H), 7.26-7.22 (m,
1H), 6.44 (d, J = 10.0 Hz, 1H), 5.90 (d, J = 10.0 Hz, 1H), 5.68 (s,
1H), 5.05 (s, 1H), 2.55 (t, J = 2.4 Hz, 2H), 1.93 (t, J = 2.4 Hz,
1H), 1.48 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 141.1, 137.4,
134.9, 131.2, 128.1, 127.5, 126.4, 126.3, 123.3, 109.6, 81.3, 70.3,
39.6, 34.2, 28.7; IR (neat) 3294, 2967, 1590, 1481, 776, 755, 638
cm-1; HRMS (EI) calcd for C15H14: 194.1096 [M]þ; found:
194.1098.
10-Methylene-9-(propa-1,2-dienyl)-9,10-dihydroanthracene
1
(6q0). Colorless oil; H NMR (400 MHz, CDCl3) δ 7.70-7.68
(m, 2H), 7.39-7.37 (m, 2H), 7.32-7.26 (m, 4H), 5.68 (s, 2H),
5.20 (dt, J = 5.6, 6.8 Hz, 1H), 4.69 (dd, J = 2.0, 6.8 Hz, 2H), 4.65
(d, J = 7.6 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 207.9,
141.4, 137.3, 135.2, 128.0, 127.9, 127.0, 124.5, 110.0. 95.6, 76.6,
46.0; IR (neat) 3060, 2922, 1952, 1478, 1032, 892, 779 cm-1
;
HRMS (EI) calcd for C15H11: 191.0861 [M - C3H3]þ; found:
191.0867.
(E)-1-Methyl-4-pentylidene-1-(prop-2-ynyl)-1,4-dihydronaph-
thalene (6r). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.70
(d, J = 8.0 Hz, 1H), 7.39 (d, J = 8.0 Hz, 1H), 726-7.19 (m, 2H),
6.71 (d, J = 10.4 Hz, 1H), 6.16 (t, J = 7.6 Hz, 1H), 5.92 (d, J =
10.0 Hz, 1H), 2.52 (d, J = 1.6 Hz, 2H), 2.34 (dt, J = 6.8, 6.8 Hz,
2H), 1.94 (t, J = 2.4 Hz, 1H), 1.51-1.34 (m, 4H), 0.93 (t, J = 7.2
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 140.4, 134.4, 132.9,
129.1, 126.9, 126.3, 126.1, 125.7, 122.3, 122.1, 81.3, 70.2, 39.2,
34.1, 31.9, 28.5, 27.4, 22.4, 14.0; IR (neat) 3307, 2956, 2116,
1-Methyl-4-methylene-1-(propa-1,2-dienyl)-1,4-dihydronaph-
thalene (6l0). Colorless oil; 1H NMR (400 MHz, CDCl3) δ
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1480, 1370, 1044, 753 cm-1; HRMS (EI) calcd for C19H22:
250.1722 [M]þ; found: 250.1729.
(d, J = 11.2 Hz, 1H), 5.33 (d, J = 16.8 Hz, 1H), 5.25 (d, J = 10.0
Hz, 1H), 4.17 (t, J = 7.2 Hz, 1H), 2.43 (dd, J = 2.8, 7.2 Hz, 2H),
1.99 (t, J = 2.8 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 138.9,
137.0, 132.8, 132.3, 131.1, 129.3, 128.7, 127.4, 127.2, 127.1,
127.0, 119.3, 82.3, 71.3, 40.1, 29.2; IR (neat) 3299, 3024, 1805,
1616, 1486, 1294, 903, 794, 749 cm-1; HRMS (EI) calcd for
C16H14: 206.1096 [M]þ; found: 206.1099.
Procedure for the Deprotection of 6o. To a solution of 6o (45.0
mg, 0.14 mmol) in THF (3.0 mL) at 0 °C was added TBAF (39.2
mg, 0.15 mmol). After the mixture was stirred for 5 h, the solvent
was removed under reduced pressure, and the residue was
purified by basic alumina column chromatography (eluent:
hexane/ethyl acetate = 5/1) to give 9 in 76% yield (22.1 mg).
(4-Methylene-1-(prop-2-ynyl)-1,4-dihydronaphthalen-1-yl)-
methanol (9). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.81
(d, J = 8.0 Hz, 1H), 7.45 (d, J = 7.6 Hz, 1H), 7.37-7.27 (m, 2H),
6.65 (d, J = 10.0 Hz, 1H), 5.95 (d, J = 10.0 Hz, 1H), 5.74 (s, 1H),
5.11 (s, 1H), 3.87-3.71 (bm, 2H), 2.74-2.60 (bm, 2H), 1.95 (t,
J = 2.4 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 137.3, 137.0,
132.9, 131.2, 130.9, 128.5, 127.3, 126.2, 123.9, 111.0, 80.6, 71.0,
70.3, 45.8, 28.6; IR (neat) 3292, 2925, 2117, 1720, 1591, 1481,
1457, 1429, 1281, 1055, 878, 778, 757, 639 cm-1; HRMS (EI)
calcd for C15H14O: 210.1045 [M]þ; found: 210.1045.
(E)-1-Allylidene-2-(prop-2-ynyl)-1,2-dihydronaphthalene (7a).
Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.55-7.52 (m, 1H),
7.21-7.19 (m, 2H), 7.04-7.02 (m, 1H), 6.88-6.79 (bm, 1H),
6.61 (d, J = 11.2 Hz, 1H), 6.50 (d, J = 5.6 Hz, 1H), 6.21-6.18
(m, 1H), 5.42-5.38 (m, 1H), 5.29-5.27 (m, 1H), 3.83-3.77 (m,
1H), 2.34-2.21 (m, 2H), 1.96 (t, J = 2.4 Hz, 1H); 13C NMR (100
MHz, CDCl3) δ 137.3, 133.1, 132.5, 132.0, 130.1, 128.5, 128.1,
127.8, 127.3. 126.8, 124.2, 119.4, 81.9, 69.9, 36.1, 25.1; IR (neat)
3296, 3031, 2923, 1616, 1480, 1453, 906, 757 cm-1; HRMS (EI)
calcd for C16H14: 206.1096 [M]þ; found: 206.1101.
(E)-1-Allylidene-4-bromo-2-(prop-2-ynyl)-1,2-dihydronaph-
thalene (7b). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.59
(d, J = 7.6 Hz, 1H), 7.51 (d, J = 7.6 Hz, 1H), 7.32-7.25 (m, 2H),
6.84-6.75 (bm, 1H), 6.61-6.57 (m, 2H), 5.43 (d, J = 16.4 Hz,
1H), 5.32 (d, J = 10.0 Hz, 1H), 3.83 (dd, J = 7.2, 7.2 Hz, 1H),
2.38-2.20 (m, 2H), 1.97 (t, J = 2.4 Hz, 1H); 13C NMR (100
MHz, CDCl3) δ 135.7, 134.2, 131.9, 131.8, 131.2, 129.8, 129.2,
128.5, 127.4, 124.6, 121.8, 120.6, 81.3, 70.7, 38.7, 24.5; IR (neat)
3296, 3028, 1620, 1319, 985, 830, 758, 640 cm-1; HRMS (EI)
calcd for C16H13Br: 284.0201 [M]þ; found: 284.0206.
(E)-1-Allylidene-4-methyl-2-(prop-2-ynyl)-1,2-dihydronaph-
thalene (7c). Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.54 (d,
J = 7.2 Hz, 1H), 7.27-7.22 (m, 3H), 6.90-6.80 (m, 1H), 6.56 (d,
J = 11.2 Hz, 1H), 6.02 (d, J = 6.0 Hz, 1H), 5.38 (d, J = 16.4 Hz,
1H), 5.26 (d, J = 10.0 Hz, 1H), 3.78-3.71 (m, 1H), 2.30-2.16
(bm, 2H), 2.08 (s, 3H), 1.94 (t, J = 2.8 Hz, 1H); 13C NMR (100
MHz, CDCl3) δ 138.2, 134.0, 133.6, 132.2, 131.6, 128.3, 128.2,
127.6, 127.1, 124.6, 123.5, 119.2, 82.3, 70.7, 36.1, 24.9, 19.5; IR
Acknowledgment. We are grateful to the National Natural
Science Foundation of China (20972021) for financial
support. This work was partly supported by the Program
for Changjiang Scholars and Innovative Research Teams in
Universities (IRT0711).
(neat) 3297, 2970, 2116, 1620, 1479, 1378, 984, 758, 633 cm-1
;
HRMS (EI) calcd for C17H16: 220.1252 [M]þ; found: 220.1261.
(E)-2-Allylidene-1-(prop-2-ynyl)-1,2-dihydronaphthalene (7d).
Colorless oil; 1H NMR (400 MHz, CDCl3) δ 7.30 (d, J = 7.2 Hz,
1H), 7.21-7.15 (m, 2H), 7.10 (d, J = 7.2 Hz, 1H), 6.87-6.78
(m, 1H), 6.41 (d, J = 9.6 Hz, 1H), 6.23 (d, J = 9.6 Hz, 1H), 6.18
Supporting Information Available: Experimental proce-
dures, characterization data for all new compounds, and
NMR spectra for the corresponding products. This mate-
rial is available free of charge via the Internet at http://pubs.
acs.org.
J. Org. Chem. Vol. 75, No. 8, 2010 2627