Lewis acid-catalyzed ring-opening functionalizations of 1,4-epoxy-1,4-dihydronaphthalenes

Article abstract of DOI:10.1002/adsc.201200771

Since 1,4-epoxy-1,4-dihydronaphthalenes are smoothly converted to 1-naphthol derivatives via unstable cation intermediates formed by the acid-catalyzed ring-opening reaction of the 1,4-epoxy moiety of 1,4-epoxy-1,4-dihydronaphthalenes, their nucleophilic functionalization using the cation intermediates as an active species is extremely difficult. We have accomplished the Lewis acid-catalyzed carboncarbon and carbon-nitrogen bond formations associated with the ring-opening of 1,4-epoxy-1,4-dihydronaphthalenes using nucleophiles such as allyltrimethylsilanes, trimethylsilyl cyanide and trimetylsilyl azide, by using the stabilization effect of the cation intermediate based on the introduction of appropriate substituents into the bridgehead positions of 1,4-epoxy-1,4-dihydronaphthalenes to give the corresponding unique and multifunctionalized naphthalene derivatives. The present reactions could provide excellent regioselective functionalization methods using unsymmetrical substrates, which are quite difficult to achieve using transition metal-induced procedures.

Full text of DOI:10.1002/adsc.201200771

FULL PAPERS
DOI: 10.1002/adsc.201200771
Lewis Acid-Catalyzed Ring-Opening Functionalizations of
1,4-Epoxy-1,4-dihydronaphthalenes
Yoshinari Sawama,a,* Yuta Ogata,a Koichi Kawamoto,b Hiroyuki Satake,b
Kyoshiro Shibata,a Yasunari Monguchi,a Hironao Sajiki,a and Yasuyuki Kitab,*
a
Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196; Japan
Fax : (+81)-58-230-8109; e-mail: sawama@gifu-pu.ac.jp
College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
b
E-mail: kita@ph.ritsumei.ac.jp
Received: August 28, 2012; Revised: November 28, 2012; Published online: February 1, 2013
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201200771.
Abstract: Since 1,4-epoxy-1,4-dihydronaphthalenes intermediate based on the introduction of appropri-
are smoothly converted to 1-naphthol derivatives via ate substituents into the bridgehead positions of 1,4-
unstable cation intermediates formed by the acid-cat- epoxy-1,4-dihydronaphthalenes to give the corre-
alyzed ring-opening reaction of the 1,4-epoxy moiety sponding unique and multifunctionalized naphtha-
of 1,4-epoxy-1,4-dihydronaphthalenes, their nucleo- lene derivatives. The present reactions could provide
philic functionalization using the cation intermedi- excellent regioselective functionalization methods
ates as an active species is extremely difficult. We using unsymmetrical substrates, which are quite diffi-
have accomplished the Lewis acid-catalyzed carbon- cult to achieve using transition metal-induced proce-
carbon and carbon-nitrogen bond formations associ- dures.
ated with the ring-opening of 1,4-epoxy-1,4-dihydro-
naphthalenes using nucleophiles such as allyltrime- Keywords: carbon-carbon and carbon-nitrogen bond
thylsilanes, trimethylsilyl cyanide and trimetylsilyl formation; Lewis acids; naphthalenes; regioselectivi-
azide, by using the stabilization effect of the cation ty; ring-opening reaction
Introduction
report related to the acid-catalyzed nucleophilic reac-
tion of 1. The 1,4-epoxy moiety of 1 can be cleaved
1,4-Epoxy-1,4-dihydronaphthalenes (1) are easily pre- under Brønsted acid or Lewis acid (LA) conditions to
pared by the Diels–Alder reaction between various form unstable cation intermediates (A) and only the
benzynes and furans, and are utilized as valuable syn- corresponding 1-naphthols (2) are generated by the
thetic precursors to construct highly functionalized fast hydride shift[1d] (R2 =H) and subsequent aromati-
naphthalene backbones.[1–9] Whereas the ring-opening zation even in the presence of nucleophiles
substitution reactions of 1 have been extensively de- (Scheme 1).[1,2]
veloped using alkyllithium[3] or transition metal re-
Meanwhile, we have recently developed the unpre-
agents[4] (Fe,[5] Cu,[6] Pd,[7] Rh,[8] Ni[9]) to afford 2-sub- cedented gold-catalyzed allylative and azidative ring-
stituted 1,2-dihydronaphthalen-1-ols, there is no opening reactions of monocyclic 2-aryldihydrofurans
Scheme 1. Acid-catalyzed ring-opening of 1,4-epoxy-1,4-dihydronaphthalenes (1).
Adv. Synth. Catal. 2013, 355, 517 – 528
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Scheme 2. Our previous work: gold-catalyzed allylative and azidative ring-opening of 2-aryldihydrofurans.
into acyclic products which might proceed via the presence of catalytic HAuCl4·3H2O[15] (5 mol%) in
zwitterionic intermediate (B) comprising a benzyl CH2Cl2 at À408C (Table 1, entry 1). However, the de-
cation and anionic aurate substructures (Scheme 2).[10] sired allylated product was never obtained due to the
Our next goal was the application of this acid-cata- fast hydride shift[1d] of the intermediate A, and only 1-
lyzed method to the ring-opening nucleophilic func- naphthol (2a) was isolated in 53% yield. 1,4-Epoxy-
tionalizations of 1,4-epoxy-1,4-dihydronaphthalenes 1,4-dihydro-1-methylnaphthalene (1b: R1 =Me, R2 =
(1) containing
a 2-aryldihydrofuran substructure H), which could stabilize the cation intermediate A
within the fused-ring molecule (Scheme 1). We now by the electron-donating property of the methyl
report the unprecedented direct conversions of 1 to 2- group, was also converted to 4-methyl-1-naphthol
allylated naphthalenes (3 and 5)[11,12] using allylsilanes, (2b) (entry 2). To prevent the hydride shift of the in-
2-cyanonaphthalenes (8)[13] using TMSCN and cis-2- termediary A, 1,4-epoxy-1,4-dihydro-1,4-dimethyl-
azido-1-hydroxy-1,2-dihydronaphthalenes (9)[14] with naphthalene (1c: R1, R2 =Me) possessing methyl
TMSN3 in the presence of gold or iron catalysts as groups at both of the bridgehead positions was then
a Lewis acid by the stablization of A resulting from used as a substrate. Consequently, the reaction of 1c
the introduction of appropriate substitutions at the with allylTMS smoothly proceeded to form the de-
1,4-bridgehead positions.
sired 2-allylnaphthalene (3c) in 82% yield as the sole
product via the regioselective nucleophilic attack of
allylTMS at the C-2 position of A and the subsequent
aromatization (entry 3).[16] Therefore, the Lewis acid
efficiencies in the transformation of 1c to 3c were
Results and Discussion
We first examined the allylative ring-opening reaction next investigated at À408C as the starting reaction
of the unsubstituted 1,4-epoxy-1,4-dihydronaphtha- temperature (Table 2).
lene (1a: R1, R2 =H) using allylTMS (4 equiv.) in the
While the reaction using NaAuCl4·2H2O gave
a mixture of 3c and the unique diastereomerically
pure tricyclic tetrahydrofuran (4c)[17] (entry 2), an im-
proved yield of 3c (93%) was obtained using AuCl3
(entry 3) and even a decrement of the AuCl3 loading
(2 mol%) and allylTMS (2 equiv.) efficiently gave 3c
in excellent yield (98%, entry 4). The AuCl3-catalyzed
reaction was strongly influenced by the solvent and
no conversion was observed in CHCl3, toluene, THF
or MeOH. Other gold catalysts (AuBr3, Ph3PAuCl/
AgSbF6) or traditional Lewis acids such as FeCl3,
Table 1. Gold-catalyzed ring-opening of 1,4-epoxy-1,4-dihy-
dronaphthalenes.
TMSOTf and In
ly lower yields of 3c were obtained (entries 5–9). In
contrast, Sc(OTf)2, Cu(OTf)2, AgSbF6 and AlBr3 re-
ACHTUNGRTEN(NUNG OTf)3 were also effective, but slight-
A
ACHTUNGTRENNUNG
sulted in obviously low yields of 3c or no reaction (en-
tries 10–13), and TFA as a Brønsted acid produced
a complex mixture (entry 14).
Encouraged by the efficient reactivity of the AuCl3-
catalyzed allylative ring-opening of 1c, the optimized
conditions (Table 2, entries 3 and 4) were adapted for
the allylation using various unsymmetrical 1,4-epoxy-
1,4-dihydronaphthalenes (1d–1l) (Table 3). The transi-
tion metal-catalyzed regioselective substitution reac-
tions of the unsymmetrical 1 bearing some functional-
ities on the aromatic ring were still difficult[4–9] be-
cause the 1,4-epoxy-1,4-dihydrobenzene ring of 1 was
not strongly controlled by the electron or steric prop-
Entry Substrate
R1
Time [h] Product: yield [%][a]
R2
1
1a: H
H
H
Me
1
1
2
2a: 53, 3a: 0
2b: 82, 3b: 0
2c: 0, 3c: 82
2
1b: Me
1c: Me
3[b]
[a]
[b]
Isolated yields.
3c was obtained in a slightly lower isolated yield (77%)
at the elevated reaction temperature (08C), although the
starting substrate (1c) was consumed only for 0.5 h.
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Lewis Acid-Catalyzed Ring-Opening Functionalizations of 1,4-Epoxy-1,4-dihydronaphthalenes
Table 2. Lewis acid efficiencies for allylative ring-opening of
1c.[a]
the reactivity and regioselectivity was observed. Sub-
strates possessing a substituent at the proximal posi-
tion (1h–1k) are less reactive under the AuCl3-cata-
lyzed reaction conditions and the addition of AgSbF6
was required to afford the desired allylated products
in high yields (entries 5–8). A clear distinction of the
reactivity is observed between substrates 1d and 1h
each bearing a methoxy group at the distal or proxi-
mal position (entry 1 vs. 5). The allylation of 1i, a di-
methoxy-substituted substrate, also gave a high yield
and regioselectivity (entry 6), while the reaction with-
out AgSbF6 was never completed and the tricyclic
compound 4i was obtained as a side-product with per-
fect regio- and stereoselectivities.[17] It is particularly
noteworthy that substrate 1j bearing a weak electron-
donating methyl group at the proximal position un-
derwent a highly regioselective allylative ring-opening
reaction in excellent yield (entry 7). The reaction of
the sterically hindered substrate (1k) also gave the al-
lylated phenanthrene (3k) in perfect regioselectivity
and moderate yield, accompanied by the tetracyclic
product (4k).[21] Additionally, 1l containing two differ-
ent substituents (Ph and Me) at the bridgehead posi-
tions gave only an allylated naphthalene product (3l)
in a high yield and regioselectivity.
Entry Lewis acid
Time [h] Yield [%] of 2c/3c/4c
1
2
HAuCl4·3H2O
NaAuCl4·2H2O
AuCl3
AuCl3
AuBr3
2
3
2
4
3
0/82/0
0/34/22
0/93/0
0/98/0
0/60/0
3[b]
4[c]
5
The electronic properties of a substituent on the ar-
omatic ring obviously affects the formation and the
regioselectivity of the benzyl cation intermediate (A),
which is derived by the regioselective cleavage of the
1,4-epoxy moiety of the substrate (Scheme 3). For ex-
ample, intermediate A’ derived from substrate 1d pos-
sessing a methoxy group at the 6-position was effi-
ciently generated due to the stabilization of the
benzyl cation by the electron-donationg effect of the
methoxy group. The intermediate A is regioselectively
attacked by the allylTMS at the C-2 position to afford
the b-silylcation intermediate (C). The subsequent
cleavage of the carbon-silicon bond leads to the allyl-
naphthol derivative (D) and the following aromatiza-
tion accompanied by TMSOH elimination gives the
2-allylnaphthalene (3c). The tricyclic tetrahydrofuran
6
7
8
9
10
11
12
13
14
Ph3P·AuCl/AgSbF6 3.5
0/77/0
0/89/0
0/82/0
30/70/0
15/23/8
0/40/0
no reaction
no reaction
complex mixture
FeCl3
2
TMSOTf
3
In
Sc
Cu
AgSbF6
AlBr3
TFA
G
6
E
18
24
24
24
18
ACHTUNGTRENNUNG
[a]
[b]
[c]
Reaction conditions: Lewis acid (5 mol%) and allylTMS
(4 equiv.) in CH2Cl2 at À40 to 08C.
Reactions in CHCl3, toluene, THF, MeOH led to no con-
version.
2 mol% of AuCl3 and 2 equiv. of allylTMS were used.
erties of the substituents on the aromatic ring.[18] The (4c) could be converted to 3c in the presence of
regioselectivity of the gold-catalyzed allylative ring- AuCl3 [Eq. (1)], which indicated that the side-product
opening of 1 was found to be strongly substrate-de- 4c derived by the trapping of the b-silylcation (C)[22]
pendent.[19] Compound 1d posessing an electron-do- by the oxygen atom is also the precursor of the 2-al-
nating methoxy group on the distal[20] position (R1) of lylnaphthalene (3c).
the aromatic ring underwent the allylation with a per-
The present allylative ring-opening reaction of 1c
fect regioselectivity and high yield (entry 1). The in- was generally applicable for the diverse allylTMS de-
troduction of a bromo substituent on the aromatic rivatives (Table 4). 2-Phenyl- or methylallylTMS (6a
ring (1e) also preferred the regioselective functionali- and 6b) were effectively reacted with 1c to afford the
zation to 3e (entry 2), whereas substrates 1f and 1g disubstituted alkene products (7a and 7b) in high
bearing an electron-withdrawing group, such as ester yields (entries 1 and 2), while a mixture of the desired
or trifluoromethyl group, gave a low regioselectivity brominated alkene (7ca) and the corresponding
even though the allylation products were obtained in ketone product (7cb), which might be generated by
high total yields (entries 3 and 4). In addition to these the hydrolysis of 7ca during the aqueous work-up pro-
electronic effects, a strong steric effect by the proxi- cess, were obtained using 2-bromoallylTMS (6c)
mal[20] substituent on the benzene ring (R2) toward (entry 3). Interestingly, the allylative ring-opening
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Table 3. Regioselective allylative ring-opening of unsymmetrical 1,4-epoxy-1,4-dihydronaphthalenes (1).
Entry
Substrate
Time [h]
Product [%] (3:5)
R1
R2
1[a]
2[b]
3[b]
4[c]
5[c]
6[c,d]
7[c]
1d: MeO
1e: Br
1f: MeO2C
1g: F3C
1h: H
1i: MeO
1j: H
H
H
H
H
MeO
MeO
Me
0.5
2.5
4
4
4
88 (100:0)
81 (88:12)
85 (31:69)
94 (50:50)
93 (100:0)
93 (100:0)
99 (91:9)
1
3
8[c]
4
9[a]
0.5
[a]
AuCl3 (2 mol%), allylTMS (2 equiv.).
AuCl3 (5 mol%), allylTMS (4 equiv.).
AuCl3 (5 mol%), AgSbF6 (15 mol%), allylTMS (4 equiv.).
32% of 3j and 32% of 4i were obtained when the reaction was performed without AgSbF6 [only AuCl3 (5 mol%), al-
lylTMS (4 equiv.)].
Tetracyclic compound 4k was also obtained in 36% yield as a single diastereomer.
[b]
[c]
[d]
[e]
using 3-phenylallylsilane (6d) as an allylative reagent and 3). The reaction of 1k condensed with a benzene
gave a mixture of regioisomers of the tetracyclic prod- ring and 1l containing two different substituents (Ph
uct (7d) (entry 4).[23]
and Me) on each bridgehead carbon also afforded the
We next studied the introduction of TMSCN as 2-cyanated phenanthrene (8k) and biaryl product (8l)
a type of carbon nucleophile to intermediate A de- in a perfect regioselectivity (entries 4 and 5).
rived from 1, since aromatic cyanides are important
Furthermore, it is noted that the present intermedi-
units in the medicinal and agrichemical fields,[13] as ate (A) could be applicable to the azidation as a C N
a useful precursor to be converted to acyl, formyl, bond formation using TMSN3, since the azido
amino, carboxylic acid and tetrazole functionalities.[24] group[26] is a useful functionality to be converted into
The HAuCl4·3H2O-catalyzed cyanative ring-opening the corresponding amine by the reduction, or triazole
reaction of 1c using TMSCN in the presence of under Huisgen reaction conditions[27] and so on.
À
À
AgSbF6 as an additive smoothly proceeded to form 2- While the ring-opening C C bond formation using
cyano-1,4-dimethylnaphthalene (8c) in 40% yield 1 and allylTMS or TMSCN afforded the 2-substited
(Table 5, entry1).[25] The cyanation was also adaptable naphthalenes, the azidation of 1c using gold catalysts,
to the unsymmetrical substrates bearing a methoxy such as AuCl3 and HAuCl4·3H2O, in CH2Cl2 stereose-
group on the aromatic ring (1d and 1h) to afford the lectively proceeded to give the cis-2-azido-1,2-dihy-
corresponding 2-cyanonaphthalenes with high regiose- dro-1-naphthol (9c)[14] even in 35 and 40% yields
lectivities and moderate yields, respectively (entries 2 without the formation of the 2-azido-1,4-dimethyl-
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Lewis Acid-Catalyzed Ring-Opening Functionalizations of 1,4-Epoxy-1,4-dihydronaphthalenes
a catalytic Lewis acid gave the non-azidated 2,4-di-
methyl-1-naphthol (2c) (entry 4). Meanwhile, FeCl3
and ZnCl2 effectively catalyzed the ring-opening azi-
dation of 1c in CH2Cl2 to give 9c in high yield (en-
tries 5 and 6). CHCl3 was also an effective solvent for
the ring-opening azidation of 1c (entries 7 and 8).
NaN3 and diphenylphosphoryl azide (DPPA) as nucle-
ophilic azido sources and toluene, THF and MeOH as
solvents facilitated no FeCl3-catalyzed azidation.
The ring-opening azidation of unsymmetrical sub-
strates proceeded in a completely regioselective
manner to give the corresponding cis-2-azido-1,2-di-
hydronaphth-1-ols in moderate to excellent yields
(Table 7, entries 1–5).[28,29] Meanwhile, the highly con-
jugated substrate (1k) was found to be converted to
the thermodynamically stable 2-azidated 1,4-dimeth-
yl-phenanthrene (10k) resulting from the nucleophilic
azidation and the subsequent aromatization associat-
ed with the dehydration (entry 6).[30]
The generation of only the 1,2-cis-isomer in
a Lewis-acid-catalyzed ring-opening azidation obvi-
ously indicates that the reaction may proceed in the
concerted pathway (Scheme 4, route a), because the
stepwise pathway via the zwitterion intermediate (A)
should provide the diastereo mixture due to the flexi-
Scheme 3. Proposed reaction mechanism.
naphthalene (10c) (Table 6, entries 1 and 2). The addi- ble conformation of A (route b). The nucleophilic
tion of AgSbF6 to the AuCl3-catalyzed reaction mix- attack of TMSN3 can stereoselectively take place at
ture was not effective in the case of the azidative the sterically open face of 1c to afford only the TMS-
ring-opening (entry 3), and the use of TMSOTf as protected cis-isomer as an intermediate. The subse-
Table 4. Variety of allylation reagents employed.
Entry
1[a]
Allylation reagent
Product
Time [h]
0.5
Yield [%]
85
2[a,b]
1
2
93
3[c]
47+23
4[c]
1
78
[a]
AuCl3 (5 mol%), AgSbF6 (15 mol%), allylsilane (4 equiv.).
The reaction was carried out at À308C.
[b]
[c]
AuCl3 (5 mol%), allyl silane (4 equiv.).
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Table 5. Ring-opening cyanation using TMSCN.
Table 7. Regioselective ring-opening azidation of unsymmet-
rical 1,4-epoxy-1,4-dihydronaphthalenes (1).
Entry Substrate
Product
Time
[h]
Yield
[%]
Entry Substrate
1[a]
Product
Time [h] Yield [%]
1
2
3
1
1
1
40
60
52
1
86
63
2[a]
24
3[a]
4[a]
5[b]
3
1
1
4
90
69
91
46
4
4
1
51
42
5[a]
[a]
The reaction was carried out without AgSbF6.
6[a,c]
Table 6. Lewis acid efficiencies for azidative ring-opening of
1c.
[a]
Reaction conditions: FeCl3 (5 mol%), TMSN3 (2 equiv.)
in CHCl3 at À408C to room temperature.
[b]
[c]
Reaction conditions: ZnCl2 (5 mol%), TMSN3 (2 equiv.)
in CHCl3 at À408C to room temperature.
A mixture of regioisomers (86:16) was obtained. The
principal product (10k) is shown.
Entry Lewis acid
Time [h] Yield [%] of 9c/10c/2c
quent and smooth cleavage of the TMS group by the
acidity of FeCl3 and/or HCl generated during the
aqueous work-up produces 9c. Since the electron-do-
nating azido group might decrease the acidity at the
C-2 position, the aromatization accompanied by the
elimination of TMSOH or H2O becomes suppressed.
Furthermore, the ring-opening functionalization of
the nitrogen-bridged substrate (11) prepared by the
Diels–Alder reaction of benzyne and N-methoxycar-
bonylpyrrole was investigated (Scheme 5). While the
allylation using AuCl3-allylTMS and cyanation using
HAuCl4·3H2O/AgSbF6-TMSCN led to complex mix-
tures, the azidative ring-opening reaction using FeCl3-
1
2
3
4
AuCl3
HAuCl4·3H2O 24
AuCl3/AgSbF6 0.5
TMSOTf
FeCl3
ZnCl2
FeCl3
24
35/0/0
40/0/0
complex mixture
0/0/80
64/6/0
86/0/1
63/0/14
86/0/0
24
4.5
15
8
5
6
7[a,b,c]
8[a]
ZnCl2
20
[a]
The reaction was carried out in CHCl3 instead of CH2Cl2.
The use of NaN3 or DPPA as an azido source led to no
reaction.
The reaction performed in toluene, THF and MeOH as
the solvent gave no conversion.
[b]
[c]
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Lewis Acid-Catalyzed Ring-Opening Functionalizations of 1,4-Epoxy-1,4-dihydronaphthalenes
spectrometer at room temperature in CDCl3 as a solvent
and internal standard (1H NMR: d=7.27; 13C NMR: d=
77.0). IR spectra were recorded by the diffuse reflectance
measurement of samples dispersed in KBr powder with
a JASCO FT/IR-4200 spectrometer or a Brucker FT-IR
ALPHA. FAB high-resolution mass spectra (HR-MS) were
measured by the JEOL JMS-D300 or JEOL JMS-600. ESI-
LC/TOF mass spectra were taken on a Shimazu hybrid IT-
TOF mass spectrometer.
Scheme 4. Proposed reaction mechanism.
General Procedure of Allylative, Cyanative or
Azidative Ring-Opening
To a solution of the substrate (1; 0.2 mmol) in CH2Cl2
(2 mL) were added allylTMS, TMSCN or TMSN3
(0.4 mmol) and a Lewis acid (0.01 mmol) [and AgSbF6
(0.03 mmol)] at À408C under argon. After being stirred
with a naturally rising reaction temperature until the reac-
tion was completed, the reaction mixture was quenched with
water and extracted with CH2Cl2 (ꢁ2). The combined organ-
ic layer was dried over Na2SO4 and concentrated under
vacuum after filtration. The residue was purified by silica
gel column chromatography using hexane-AcOEt as the
eluent to give the corresponding naphthalene derivative (3,
5, 7–9).
Scheme 5. Ring-opening functionalizations using nitrogen-
bridged substrate (11).
Spectroscopic Data of Products
TMSN3 efficiently proceeded to give the correspond-
ing cis-1-methoxycarbonylamino-2-azide-1,2-dihydro- 2-Allyl-1,4-dimethylnaphthalene (3c): colorless oil; IR
(KBr): n=3073, 2973, 2866, 1943, 1637, 1511, 1442, 1386,
naphthalene (12) in 80% yield.
1
1267, 1164, 1072, 992 cmÀ1; H NMR (400 MHz, CDCl3): d=
8.07 (1H, dd, J=7.2, 1.2 Hz), 7.98 (1H, dd, J=7.2, 1.2 Hz),
7.52–7.46 (2H, m), 7.15 (1H, s), 6.05–5.97 (1H, m), 5.06
(1H, dt, J=10.0, 1.6), 5.00 (1H, dq, J=17.2, 1.6 Hz), 3.57
(2H, dt, J=6.4, 1.6), 2.66 (3H, s), 2.60 (3H, s); 13C NMR
(100 MHz, CDCl3): d=136.9, 134.2, 133.1, 131.9, 131.6,
129.4, 129.2, 125.4, 124.6, 124.5, 124.4, 115.3, 38.6, 19.2, 14.2;
FAB-HR-MS: m/z=197.1293 ([M+H]+); calcd. for C15H16:
196.1325.
Conclusions
We have established the novel Lewis acid-catalyzed
ring-opening allylation, cyanation and azidation of
1,4-disubstituted 1,4-epoxy-1,4-dihydronaphthalenes
(1) to construct unique, useful and highly functional-
ized naphthalene derivatives (3, 5, 7–9) as building
blocks. The present C C and C N bond formations
could be accomplished under mild conditions with
a high regioselectivity in high yield and additionally,
furnish products which could not be achieved by the
previous transition metal-catalyzed methods. These
methods would increase the utility of the 1,4-epoxy-
1,4-dihydronaphthalenes as synthetic precursors.
Moreover, the simplicity of these methods makes
them attractive new synthons for organic chemists.
2-Allyl-7-methoxy-1,4-dimethylnaphthalene (3d): light-
yellow oil; IR (KBr): n=3076, 2938, 2443, 1901, 1517, 1381,
À
À
1
1271, 1177, 1058 cmÀ1; H NMR (400 MHz, CDCl3): d=7.92
(1H, d, J=9.4 Hz), 7.36 (1H, d, J=2.8 Hz), 7.21 (1H, dd,
J=9.4, 2.8 Hz), 7.05 (1H, s), 6.10–6.0 (1H, m), 5.09 (1H, dd,
J=10.4, 1.6 Hz), 5.02 (1H, dd, J=17.0, 1.6 Hz), 3.98 (3H, s),
3.58 (2H, d, J=6.0 Hz), 2.66 (3H, s), 2.58 (3H, s); 13C NMR
(400 MHz, CDCl3): d=157.4, 137.0, 135.0, 134.4, 131.9,
128.1, 127.1, 126.9, 126.1, 116.4, 115.2, 103.6, 55.2, 38.7, 19.2,
14.4; FAB-HR-MS: m/z=226.1360 ([M]+); calcd. for
C16H18O: 226.1358.
2-Allyl-7-bromo-1,4-dimethylnaphthalene (3e): colorless
solid; 88:12 mixture of regioisomers (3e and 5e); IR (KBr):
n=3075, 2974, 2864, 1610, 1498, 1440, 1380, 1295, 1238,
1164, 1053 cmÀ1; spectra of only 3e: 1H NMR (400 MHz,
CDCl3): d=8.21 (1H, d, J=2.0 Hz), 7.83 (1H, d, J=8.8 Hz),
7.55 (1H, dd, J=8.8, 2.0 Hz), 7.15 (1H, s), 6.05–5.95 (1H,
m), 5.08 (1H, dd, J=10.2, 1.6 Hz), 4.98 (1H, dd, J=17.2,
1.6 Hz), 3.55 (2H, d, J=6.0 Hz), 2.63 (3H, s), 2.54 (3H, s);
spectra of mixture of 3e and 5e: 13C NMR (100 MHz,
CDCl3): d=136.6, 135.6, 134.9, 134.6, 133.0, 132.1, 131.7,
131.2, 130.3, 130.1, 129.7, 129.6, 128.7, 128.6, 127.8, 126.9,
126.8, 126.4, 126.3, 120.0, 119.0, 115.6, 115.6, 38.5, 38.5, 19.1,
Experimental Section
Materials and Methods
Substrates (1c–1l) were prepared by Diels–Alder reaction
between the in situ generated benzyne and furans.[11] All re-
actions were performed in oven-dried glassware under nitro-
gen or argon. Column chromatography was carried out with
Merck Silica Gel 60 (230–400 mesh). 1H NMR and
13C NMR spectra were recorded with a JEOL JMN-400
Adv. Synth. Catal. 2013, 355, 517 – 528
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
523

Yoshinari Sawama et al.
FULL PAPERS
19.1, 14.2, 14.2; FAB-HR-MS: m/z=274.0359 ([M]+); calcd.
for C15H15Br: 274.0357.
129.3, 128.5, 124.9, 124.3, 123.2, 123.1, 115.4, 115.3, 39.2,
38.4, 26.9, 26.2, 26.0, 19.7, 15.1; FAB-HR-MS: m/z=
210.1411 ([M]+); calcd. for C16H18: 210.1409.
2-Allyl-6-methoxycarbonyl-1,4-dimethylnaphthalene (5f):
colorless solid; 31:69 mixture of regioisomers (3f and 5f);
IR (KBr): n=3077, 2450, 2738, 1720, 1619, 1435, 1382, 1356,
2-Allyl-1,4-dimethylphenanthrene (3k): colorless solid;
mp 45–478C; IR (KBr): n=3049, 3001, 2921, 2870, 2733,
1282, 1258, 1225, 1114 cmÀ1
;
1H NMR (400 MHz, CDCl3):
1762, 1637, 1590, 1527, 1467, 1453, 1378, 1295, 992, 912 cmÀ1
;
d=8.85 (0.45H, d, J=1.6 Hz), 8.74 (1H, s), 8.08: d=8.00
(2.9H, m), 7.24 (0.45H, s), 7.20 (1H, s), 6.05: d=5.95
(1.45H, m), 5.01–5.00 (2.9H, m), 4.00 (4.35H, s), 3.57 (2.9H,
d, J=6.0 Hz), 2.72 (3H, s), 2.66 (2.7H, s), 2.59 (3H, s);
13C NMR (100 MHz, CDCl3): d=167.6, 137.1, 136.5, 136.4,
135.5, 135.2, 133.6, 132.4, 131.9, 131.6, 130.9, 130.0, 129.5,
127.6, 127.6, 126.7, 125.9, 124.8, 124.8, 124.8, 124.0, 115.7,
115.6, 52.1, 52.1, 38.6, 38.4, 19.3, 19.2, 14.3, 14.3; FAB-HR-
MS: m/z=255.1349 ([M+H]+); calcd. for C17H18O2:
254.1380.
1H NMR (400 MHz, CDCl3): d=8.87 (1H, d, J=8.4 Hz),
8.04 (1H, d, J=9.0 Hz), 7.92 (1H, dd, J=7.6, 1.6 Hz), 7.76
(1H, d, J=9.0 Hz), 7.63–7.56 (2H, m), 7.33 (1H, s), 6.12–
6.02 (1H, m), 5.11 (1H, dd, J=10.2, 1.6 Hz), 5.03 (1H, dd,
J=17.0, 1.6 Hz), 3.63 (2H, d, J=6.0 Hz), 3.11 (3H, s), 2.67
(3H, s); 13C NMR (100 MHz, CDCl3): d=136.9, 135.2,
133.1, 132.9, 132.7, 132.7, 131.8, 130.4, 129.1, 128.3, 127.6,
126.8, 125.5, 125.3, 123.5, 115.6, 38.5, 27.2, 15.2; FAB-HR-
MS: m/z=246.1408 ([M]+); calcd. for C19H18: 246.1409.
3-Allyl-4-methyl-1-phenylnaphthalene (3l): colorless oil:
IR (KBr): n=3074, 2975, 1948, 1637, 1573, 1493, 1413, 1258,
2-Allyl-7-trifluoromethyl-1,4-dimethylnaphthalene
(3g):
1
colorless oil; 50:50 mixture of regioisomers (3g and 5g); IR
(KBr): n=3081, 2927, 1912, 1637, 1607, 1478, 1442, 1384,
1026, 913 cmÀ1; H NMR (400 MHz, CDCl3): d=8.09 (1H,
d, J=8.8 Hz), 7.86 (1H, d, J=8.4 Hz), 7.52–7.34 (7H, m),
7.23 (1H, d, J=2.8 Hz), 6.06–5.97 (1H, m), 5.04 (1H, dt, J=
10.0, 1.6 Hz), 5.00 (1H, dt, J=17.2, 1.6 Hz), 3.61 (2H, dd,
J=6.0, 1.2 Hz), 2.65 (3H, s); 13C NMR (100 MHz, CDCl3):
d=140.9, 138.3, 136.7, 134.3, 133.3, 131.0, 130.6, 130.2, 129.5,
128.2, 127.0, 126.5, 125.7, 124.9, 124.2, 115.6, 38.7, 14.5;
FAB-HR-MS: m/z=258.1386 ([M]+); calcd. for C20H18:
258.1409.
1363, 1316, 1159, 1086, 993, 897, 821, 735, 675 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=8.37 (1H, s), 8.27 (1H, s),
8.16 (1H, d, J=8.8 Hz), 8.08 (1H, d, J=8.8 Hz), 7.69–7.65
(2H, m), 7.27 (1H, m), 7.25 (1H, s), 6.06–6.00 (2H, m), 5.09
(2H, m), 5.06 (2H, m), 3.58 (4H, m), 2.70 (3H, s), 2.68 (3H,
s), 2.63 (3H, s), 2.61 (3H, s); 13C NMR (100 MHz, CDCl3):
d=136.8, 136.4, 136.4, 135.8, 134.5, 132.9, 132.2, 132.1, 131.4,
130.6, 130.5, 130.4, 129.6, 127.3, 126.5, 125.6, 125.6, 122.2,
122.2, 121.0, 121.0, 120.2, 120.2, 115.8, 115.7, 38.6, 38.5, 19.2,
19.1, 14.3, 14.2; FAB-HR-MS: m/z=264.1140 ([M]+); calcd.
for C16H15F3: 264.1126.
(Æ)-{(2S,3aR,9bR)-(5,9b)-Dimethyl-2,3,3a,9b-tetrahydro-
naphthoACHTUNTRGNEU[GN 1,2-b]furan-2-ylmethyl}trimethylsilane (4c): color-
less oil; IR (KBr): n=3062, 3029, 2958, 1483, 1416, 1364,
1
1247, 1188, 1143, 1090, 1155, 1032 cmÀ1; H NMR (400 MHz,
2-Allyl-5-methoxy-1,4-dimethylnaphthalene (3h): dark
brown oil; IR (KBr): n=3075, 2963, 2837, 1673, 1597, 1510,
CDCl3): d=7.67 (1H, d, J=6.8 Hz), 7.34–7.25 (3H, m), 5.90
(1H, dd, J=6.4, 1.2 Hz), 4.24–4.16 (1H, m), 2.69–2.63 (1H,
m), 2.31–2.25 (1H, m), 2.12 (3H, s), 1.40 (3H, s), 1.37–1.29
(1H, m), 1.16–1.12 (1H, m), 0.70–0.64 (1H, m), 0.03 (9H,
s); 13C NMR (100 MHz, CDCl3): d=142.1, 131.4, 130.1,
127.6, 126.6, 126.5, 125.0, 122.5, 80.8, 74.9, 46.8, 42.4, 29.5,
25.4, 19.5, À0.8, À1.0; FAB-HR-MS: m/z=286.1751 ([M]+);
calcd. for C18H26OSi: 286.1753.
1
1436, 1338, 1243, 1179, 1112, 1038 cmÀ1; H NMR (400 MHz,
CDCl3): d=7.64 (1H, d, J=8.8 Hz), 7.40 (1H, m), 7.04 (1H,
s), 6.82 (1H, d, J=7.6 Hz), 6.07–5.98 (1H, m), 5.06 (1H, dt,
J=10.0, 1.6 Hz), 5.00 (1H, dt, J=17.4, 1.6 Hz), 3.93 (3H, s),
3.55 (2H, dd, J=6.0, 1.6 Hz), 2.87 (3H, s), 2.56 (3H, s);
13C NMR (100 MHz, CDCl3): d=158.5, 136.9, 135.7, 134.7,
132.9, 130.9, 128.8, 125.4, 124.2, 117.0, 115.3, 104.5, 55.3,
38.5, 25.3, 15.0; FAB-HR-MS: m/z=226.1356 ([M]+); Calcd
for C16H18O: 226.1358.
(Æ)-{(2S,3aR,9bR)-(6,8)-Dimethoxy-5,9b-dimethyl-
2,3,3a,9b-tetrahydronaphthoACHTNUTRGNE[UNG 1,2-b]furan-2-ylmethyl}trime-
thylsilane (4i): colorless oil; IR (KBr): n=2957, 2925, 2836,
2-Allyl-5,7-dimethoxy-1,4-dimethylnaphthalene (3i): dark
orange solid; m.p. 81–838C: IR (KBr): n=3077, 2933, 1513,
1636, 1601, 1573, 1461, 1419, 1380, 1363, 1350, 1299, 1284,
1247, 1205, 1247, 1148, 1087, 1051, 982 cmÀ1 1H NMR
;
1
1411, 1366, 1208, 1059, 994, 912 cmÀ1; H NMR (400 MHz,
(400 MHz, CDCl3): d=6.86 (1H, d, J=2.4 Hz), 6.33 (1H, d,
J=2.4 Hz), 5.61 (1H, d, J=6.8 Hz), 4.18–4.11 (1H, m), 3.83
(3H, s), 3.77 (3H, s), 2.47 (1H, m), 2.20 (3H, s), 2.14 (1H,
m), 1.31 (3H, s), 1.29 (1H, m), 1.09 (1H, dd, J=14.0,
5.2 Hz), 0.59 (1H, dd, J=14.0, 9.8 Hz), À0.03 (9H, s);
13C NMR (100 MHz, CDCl3): d=159.6, 157.4, 146.7, 130.9,
122.7, 114.3, 103.1, 97.9, 81.8, 75.6, 55.4, 55.4, 46.2, 41.1, 28.2,
25.9, 24.1, À1.0. FAB-HR-MS: m/z=346.1981 ([M]+); calcd.
for C20H30OSi : 346.1964.
CDCl3): d=6.90 (1H, s), 6.87 (1H, d, J=2.4 Hz), 6.49 (1H,
d, J=2.4 Hz), 6.06–5.96 (1H, m), 5.05 (1H, dt, J=10.0,
1.6 Hz), 4.98 (1H, dt, J=17.2, 1.6 Hz), 3.95 (3H, s), 3.90
(3H, s), 3.53 (2H, d, J=6.0 Hz), 2.81 (3H, s), 2.50 (3H, s);
13C NMR (400 MHz, CDCl3): d=159.7, 157.5, 137.0, 136.3,
135.3, 132.9, 128.8, 127.6, 120.0, 115.2, 97.2, 95.6, 55.2, 55.1,
38.7, 25.0, 15.1; FAB-HR-MS: m/z=256.1457 ([M]+); calcd.
for C17H20O2: 256.1463.
2-Allyl-5-methyl-1,4-dimethylnaphthalene (3j): colorless
solid; 91:9 mixture of regioisomers (3j and 5j); IR (KBr):
n=3076, 2974, 2869, 1598, 1459, 1387, 1295, 1227, 1148,
ACHUTGTNREN{NUG (5,11b)-Dimethyl-2,3,3a,11b-tetrahydrophenanthroACHTUNGTRENNUNG[1,2-
b]furan-2-ylmethyl}trimethylsilane (4k): colorless oil; IR
(KBr): n=3056, 2950, 1508, 1420, 1357, 1247, 1194, 1175,
1037 cmÀ1; spectra of only 3i: H NMR (400 MHz, CDCl3):
1150, 1116, 1072, 1026, 947 cmÀ1 1H NMR (400 MHz,
;
1
d=8.07 (1H, d, J=8.4 Hz), 7.47 (1H, m), 7.37 (1H, d, J=
5.6 Hz), 7.22 (1H, s), 6.20–6.10 (1H, m), 5.20 (1H, dq, J=
10.2, 1.6 Hz), 5.12 (1H, dq, J=17.2, 1.6 Hz), 3.68 (2H, dd,
J=6.0, 1.6 Hz), 3.06 (3H, s), 3.03 (3H, s), 2.70 (3H, s); spec-
tra of mixture of 3i and 5i: 13C NMR (100 MHz, CDCl3): d=
136.9, 135.8, 134.9, 133.9, 133.1, 132.1, 132.0, 130.1, 129.8,
CDCl3): d=7.90–7.84 (2H, m), 7.80 (1H, d, J=8.4 Hz), 7.57
(1H, d, J=8.4 Hz), 7.49–7.43 (2H, m), 6.40 (1H, d, J=
6.8 Hz), 3.07–3.00 (1H, m), 2.81–2.75 (1H, m), 2.29 (3H, s),
2.21–2.13 (1H, m), 2.03 (3H, s), 1.99–1.88 (1H, m), 1.34–
1.26 (1H, m), 1.02–0.97 (1H, m), 0.00 (9H, s); 13C NMR
(100 MHz, CDCl3): d=209.5, 139.7, 137.1, 136.0, 132.7,
524
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 517 – 528

Lewis Acid-Catalyzed Ring-Opening Functionalizations of 1,4-Epoxy-1,4-dihydronaphthalenes
130.4, 128.3, 127.1, 126.3, 125.8, 125.5, 125.0, 123.3, 50.5,
47.6, 36.0, 28.7, 22.7, 19.8, À0.6. FAB-HR-MS: m/z=
336.1919 ([M]+); calcd. for C17H14O2:336.1909.
mixture of isomers): d=147.3, 141.8, 136.2, 130.7, 128.3,
128.0, 127.4, 127.2, 126.5, 126.4, 125.5, 125.4, 125.4, 67.8,
57.5, 50.3, 48.9, 23.4, 22.1, 17.3, 0.0, À0.1; ESI-HR-MS: m/
z=385.1996 ([M+Na]+); calcd. for C24H30ONaSi: 385.1958.
2-Cyano-1,4-dimethylnaphthalene (8c): yellow solid; mp
1078C; IR (KBr): n=3072, 2925, 2870, 2218, 1957, 1930,
1766, 1601, 1510, 1469, 1444, 1409, 1389, 1251, 1208, 1173,
1,4-Dimethyl-2-(2-phenyl-2-propenyl)naphthalene
(7a):
pale yellow oil; IR (ATR): n=3058, 3021, 2921, 2858, 1688,
1625, 1601, 1574, 1511, 1493, 1443, 1414, 1386, 1320, 1250,
1156, 1071, 1028, 999, 897, 873, 841, 777, 752, 702, 640, 593,
571, 534, 421 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=8.11
1085, 1036, 957, 913, 885, 751, 706 cmÀ1; H NMR (400 MHz,
1
(1H, d, J=8.0 Hz), 8.01 (1H, d, J=8.0 Hz), 7.56–7.49 (4H,
m), 7.40–7.29 (3H, m), 7.20 (1H, s), 5.46 (1H, s), 4.69 (1H,
s), 3.98 (2H, s), 2.67 (3H, s), 2.60 (3H, s); 13C NMR
(100 MHz, CDCl3): d=146.5, 141.6, 134.0, 133.1, 131.8,
131.7, 130.0, 129.7, 128.3, 127.5, 125.8, 125.4, 124.7, 124.5,
113.9, 39.6, 19.3, 14.4; ESI-MS: m/z=273.1617 ([M+H]+);
calcd. for C21H21: 273.1638.
CDCl3): d=8.09 (1H, dd, J=7.8, 1.7 Hz), 8.03 (1H, dd, J=
7.8, 1.7 Hz), 7.70–7.61 (2H, m), 7.39 (1H, s), 2.90 (3H, s),
2.67 (3H, s); 13C NMR (400 MHz, CDCl3): d=139.5, 134.0,
133.8, 131.8, 128.3, 127.0, 126.6, 125.5, 124.9, 119.2, 109.3,
19.2, 17.6; ESI-HR-MS: m/z=182.0942 ([M+H]+); calcd.
for C13H12N: 182.0964.
2-Cyano-7-methoxy-1,4-dimethylnaphthalene (8d): yellow
solid; mp 88–898C; IR (KBr): n=2938, 2220, 1618, 1513,
1,4-Dimethyl-2-(2-methyl-2-propenyl)naphthalene
(7b):
pale yellow oil; IR (ATR): n=3072, 2967, 2923, 2866, 1650,
1420, 1386, 1280, 1225, 1027, 945, 912, 818, 709 cmÀ1
;
1602, 1512, 1443, 1414, 1386, 1274, 1223, 1164, 1031, 947,
1H NMR (400 MHz, CD3OD): d=8.00 (1H, d, J=9.0 Hz),
7.38 (1H, d, J=2.7 Hz), 7.34 (1H, dd, J=9.0, 2.7 Hz), 7.27
(1H, s), 3.96 (3H, s), 2.82 (3H, s), 2.62 (3H, s); 13C NMR
(400 MHz, CDCl3): d=158.2, 137.6, 133.6, 133.1, 129.3,
126.4, 124.6, 120.2, 119.3, 109.8, 104.0, 55.3, 19.2, 17.8; FAB-
HR-MS: m/z=211.0873 ([M]+); calcd. for C14H13NO:
211.0992.
890, 819, 753, 733, 670, 666, 650, 581, 490, 466, 421 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=8.08 (1H, d, J=8.0 Hz),
7.98 (1H, d, J=8.0 Hz), 7.55–7.46 (2H, m), 7.14 (1H, s),
4.82 (1H, s), 4.53 (1H, s), 3.50 (2H, s), 2.66 (3H, s), 2.58
(3H, s), 1.78 (3H, s); 13C NMR (100 MHz, CDCl3): d=
144.7, 134.3, 133.2, 131.7, 131.6, 129.9, 129.7, 125.4, 124.6,
124.60, 124.55, 124.48, 111.4, 42.5, 22.8, 19.2, 14.3; ESI-HR-
MS: m/z=210.1403 ([M]+); calcd. for C16H18: 210.1380.
2-(2-Bromo-2-propenyl)-1,4-dimethylnaphthalene (7ca):
pale yellow oil; IR (ATR): n=3072, 2922, 1626, 1602, 1512,
1442, 1415, 1387, 1309, 1249, 1193, 1159, 1107, 1076, 1031,
998, 936, 888, 850, 752, 730, 699, 652, 635, 610, 586, 573, 547,
2-Cyano-5-methoxy-1,4-dimethylnaphthalene (8h): light
yellow oil; IR (ATR): n=3072, 2934, 2858, 2220, 1595, 1578,
1510, 1494, 1458, 1439, 1415, 1392, 1266, 1242, 1218, 1200,
1181, 1162, 1115, 1062, 1041, 1007, 898, 870, 830, 805, 778,
750, 705, 670, 666, 639, 420 cmÀ1
;
1H NMR (400 MHz,
CDCl3): d=7.61 (1H, d, J=8.4 Hz), 7.49 (1H, t), 7.26 (1H,
s), 6.96 (1H, d, J=7.6 Hz), 3.94 (3H, s), 2.84 (6H, s);
13C NMR (400 MHz, CDCl3): d=158.6, 138.5, 135.2, 134.4,
128.2, 127.3, 126.8, 119.3, 117.8, 110.2, 108.0, 25.4, 18.6; ESI-
MS: m/z=211.0962 ([M]+); calcd. for C14H13NO: 211.0992.
2-Cyano-1,4-dimethyl-phenanthrene (8k): colorless solid;
mp 1338C; IR (KBr): n=2926, 2874, 2219, 1725, 1587, 1528,
1470, 1453, 1430, 1413, 1385, 1328, 1276, 1264, 1231, 1206,
526, 468, 420 cmÀ1 1H NMR (400 MHz, CDCl3): d=8.12–
;
8.07 (1H, m), 8.02–7.98 (1H, m), 7.57–7.50 (2H, m), 7.15
(1H, s), 5.50 (1H, dd, J=2.8, 2.0 Hz), 5.31 (1H, dd, J=3.6,
2.0 Hz), 3.93 (2H, s), 2.67 (3H, s), 2.59 (3H, s); 13C NMR
(100 MHz, CDCl3): d=133.1, 132.2, 132.1, 132.0, 130.5,
129.2, 125.7, 125.2, 124.7, 124.6, 117.6, 46.2, 19.3, 14.5; ESI-
HR-MS: m/z=273.0185 ([MÀH]À); calcd. for C15H14Br:
273.0284.
1
1142, 1031, 967, 943, 866, 818, 795 cmÀ1; H NMR (400 MHz,
1,4-Dimethyl-2-(2-oxopropyl)naphthalene (7cb): pale
yellow oil; IR (ATR): n=3071, 3001, 2922, 2856, 1710, 1602,
1512, 1469, 1449, 1415, 1388, 1355, 1313, 1270, 1232, 1212,
1158, 1033, 1014, 886, 755, 692, 639, 588, 537, 501, 466,
CDCl3): d=8.87 (1H, d, J=9.5 Hz), 7.99–7.95 (2H, m), 7.86
(1H, d, J=9.3 Hz), 7.71–7.67 (2H, m), 7.63 (1H, s), 3.11
(3H, s), 2.96 (3H, s); 13C NMR (100 MHz, CDCl3): d=
138.0, 134.4, 133.8, 133.1, 132.0, 131.8, 131.0, 128.7, 128.6,
128.0, 127.3, 126.2, 122.9, 119.0, 110.1, 27.1, 18.5; FAB-HR-
MS: m/z=232.1136 ([M+H]+); Calcd for C17H14N:
232.1121.
2-Cyano-1-methyl-4-phenyl-naphthalene (8l): colorless
solid; mp 74–768C; IR (KBr): n=3058, 2926, 2867, 2223,
1956, 1725, 1593, 1511, 1491, 1443, 1406, 1389, 1249, 1206,
1
421 cmÀ1; H NMR (400 MHz, CDCl3): d=8.07 (1H, dd, J=
10.0, 2.4 Hz), 7.99 (1H, dd, J=7.6, 2.4 Hz), 7.57–7.50 (2H,
m), 7.12 (1H, s), 3.89 (2H, s), 2.67 (3H, s), 2.57 (3H, s),
2.14 (3H, s); 13C NMR (100 MHz, CDCl3): d=206.55, 133.1,
132.5, 132.0, 130.4, 129.5, 129.4, 125.7, 125.1, 124.6, 124.5,
50.0, 29.2, 19.2, 14.8 ; ESI-MS: m/z=213.1285 ([M+H]+);
calcd. for C15H16O: 213.1274.
1175, 1120, 1074, 1029, 913, 887, 784, 762, 748, 703 cmÀ1
;
(Æ)-{(2S,3S,9bR)-5,9b-dimethyl-4-phenyl-2,2,3a,9b-tetra-
1H NMR (400 MHz, CDCl3): d=8.16 (1H, d, J=7.8 Hz),
7.93 (1H, d, J=8.3 Hz), 7.67–7.43 (8H, m), 2.99 (3H, s);
13C NMR (100 MHz, CDCl3): d=140.6, 139.8, 138.9, 133.1,
132.1, 129.9, 128.5, 128.4, 128.3, 127.9, 127.2, 127.0, 125.2,
119.0, 109.4, 17.9; FAB-HR-MS: m/z=244.1107 ([M+H]+);
calcd. for C18H14N: 243.1048.
hydronaphthoACHTUNGTRENNUNG[1,2-b]furan-2-ylmethyl}trimethylsilane (7d):
72:28 mixture of regioisomers; colorless oil; IR (ATR): n=
3446, 3059, 3024, 2960, 2923, 1602, 1496, 1479, 1411, 1376,
1332, 1245, 1206, 1143, 1067, 1035, 987, 958, 844, 792, 771,
752, 726, 702, 687, 671, 666, 658, 620, 591, 559, 527, 497, 466,
419 cmÀ1; spectra of major isomer: 1H NMR (400 MHz,
CDCl3): d=7.36–7.21 (6H, m), 7.16, (1H, t, J=7.6 Hz), 7.01
(1H, t, J=7.6 Hz), 6.78 (1H, t, J=7.6 Hz), 5.63 (1H, dd, J=
6.8, 1.4 Hz), 3.9–3.83 (1H, m), 3.65, (1H, d, J=10.8 Hz),
3.21 (1H, dt, J=5.4 Hz), 2.20 (3H, d, 1.4 Hz),1.13, (3H, d,
J=6.0 Hz), 0.89, (1H, dd, J=15.4, 5.4 Hz), 0.54 (1H, dd, J=
15.4, 4.8 Hz), À0.17 (9H, s); 13C NMR (100 MHz, CDCl3;
cis-2-Azido-1,4-dimethyl-1-hydroxy-1,2-dihydronaphtha-
lene (9c): colorless oil; IR (ATR): n=3447, 3033, 2976,
2925, 2098, 1643, 1485, 1452, 1357, 1307, 1246, 1175, 1096,
1067, 1048, 1035, 984, 953, 918, 862, 820, 758, 659, 583, 551,
1
524 cmÀ1; H NMR (400 MHz, CDCl3): d=7.69 (1H, d, J=
7.2 Hz), 7.36–7.30 (3H, m), 5.97 (1H, dd, J=1.2, 6.0 Hz),
3.86 (1H, d, J=6.0 Hz), 2.66 (1H, brs), 2.20 (3H, d, J=
Adv. Synth. Catal. 2013, 355, 517 – 528
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
525

Yoshinari Sawama et al.
FULL PAPERS
1.2 Hz), 1.42 (3H, s); 13C NMR (100 MHz, CDCl3): d=
141.7, 138.3, 132.4, 129.3, 127.9, 124.7, 124.2, 119.0, 73.4,
127.2, 124.8, 120.3, 73.5, 64.6, 27.0; ESI-MS: m/z=300.1107
([M+Na]+); calcd. for C17H15N3ONa: 300.1113.
2-Azido-1,4-dimethylphenanthrene (10k): 84:16 mixture
of regioisomers (10k and 11k); IR (KBr): n=2927, 2362,
2217, 1725, 1596, 1463, 1443, 1391, 1254, 1117, 1040, 913,
878, 847, 797, 752 cmÀ1; spectra of only 10k: 1H NMR
(400 MHz, CDCl3): d=1H NMR (400 MHz, CDCl3): d=
8.72–8.69 (1H, m), 7.92–7.90 (1H, m), 7.85 (1H, d, J=
8.8 Hz), 7.69 (1H, d, J=8.8 Hz), 7.62–7.56 (1H, m), 7.27
(1H, s), 2.89 (1H, s), 2.74 (1H, s); spectra of mixture of 10k
and 11k: 13C NMR (100 MHz, CDCl3): d=149.5, 136.8,
134.9, 134.7, 133.9, 133.6, 132.5, 132.1, 131.6, 131.1, 129.3,
128.5, 128.31, 128.26, 127.9, 127.3, 126.3, 126.2, 125.7, 125.6,
125.0, 123.7, 123.2, 122.7, 120.8, 117.9, 116.0, 27.3, 20.2, 19.4,
65.1,
27.2,
19.4;
ESI-MS:
m/z=215.1119 ([M]+); calcd. for C12H13N3O: 215.1053.
cis-2-Azido-1,4-dimethyl-1-hydroxy-7-methoxy-1,2-dihy-
dronaphthalene (9d): light yellow oil; IR (ATR): n=2954,
2094, 1608, 1570, 1517, 1493, 1453, 1422, 1381, 1366, 1347,
1309, 1282, 1248, 1227, 1177, 1154, 1116, 1088, 1056, 1032,
1007, 944, 900, 839, 755, 712, 694, 625, 559, 447 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=7.27–7.23 (2H, m), 6.79
(1H, dd, J=8.8, 2.8 Hz), 5.84 (dd, J=6.0, 1.2 Hz), 3.85 (3H,
s), 3.84–3.82 (1H, m), 2.73 (1H, brs), 2.16 (3H, s), 1.40 (3H,
s); 13C NMR (100 MHz, CDCl3): d=160.6, 143.9, 138.1,
125.8, 125.5, 116.4, 112.7, 110.6, 73.6, 65.4, 55.5, 27.1, 19.4;
ESI-MS m/z: 245.1193 ([M]+); calcd. for C13H15N3O2:
245.1159.
14.1; ESI-HR-MS: m/z=248.1297ACHTUNGTRNEUNG
([M+H]+); calcd. for
C14H13N3: 248.1182.
cis-2-Azido-1,4-dimethyl-5-methoxy-1-methoxycarbonyl-
amino-1,2-dihydronaphthalene (12): light yellow oil; IR
(ATR): n=3338, 2982, 2950, 2094, 1721, 1649, 1507, 1488,
1450, 1371, 1353, 1298, 1255, 1226, 1128, 1069, 1044, 986,
cis-2-Azido-7-bromo-1,4-dimethyl-1-hydroxy-1,2-dihydro-
naphthalene (9e): colorless oil; IR (ATR): n=3449, 2976,
2925, 2098, 1643, 1588, 1556, 1476, 1449, 1396, 1357, 1307,
1249, 1174, 1143, 1098, 985, 953, 894, 864, 831, 772, 733, 665,
964, 902, 866, 821, 759, 697, 670, 606, 581, 487 cmÀ1
;
542, 502, 428 cmÀ1 1H NMR (400 MHz, CDCl3): d=7.83
;
1H NMR (400 MHz, CDCl3): d=7.47 (1H, m), 7.34 (3H,
m), 5.96 (1H, dd, J=6.4, 1.2 Hz), 5.44 (1H, brs), 4.34 (1H,
d, J=6.4 Hz), 3.71 (3H, s), 2.19, (3H, d, J=1.2 Hz), 1.71
(3H, s); 13C NMR (125 MHz, CDCl3): d=156.6, 139.1,
136.8, 132.2, 129.0, 127.9, 124.7, 124.0, 119.4, 61.6, 58.5, 52.0,
24.7, 19.3; FAB-HR-MS: m/z=295.1664 ([M+Na]+); calcd.
for C14H16N4O2Na: 295.1165.
(1H, d, J=2.0 Hz), 7.42 (1H, dd, J=8.4, 2.0 Hz), 7.15 (1H,
d, J=8.4 Hz), 5.99 (1H, dd, J=6.4, 1.2 Hz), 3.85 (1H, d, J=
6.4 Hz), 2.69 (1H, d, J=1.2 Hz), 2.17 (3H, s), 1.41 (3H, s);
13C NMR (400 MHz, CDCl3): d=143.9, 137.4, 131.2, 130.8,
128.1, 125.7, 123.3, 119.3, 73.0, 64.5, 26.9, 19.1; ESI-MS: m/
z=316.0046 ([M+Na]+); calcd. for C12H12BrN3NaO:
316.0061.
cis-2-Azido-1,4-dimethyl-1-hydroxy-5-methoxy-1,2-dihy-
dronaphthalene (9h): light yellow oil; IR (ATR): n=3545,
2971, 2929, 2838, 2100, 1632, 1593, 1572, 1470, 1437, 1353,
1269, 1226, 1187, 1166, 1069, 1044, 992, 954, 909, 866, 797,
Acknowledgements
754, 733, 672, 648, 555, 528, 484, 422 cmÀ1
;
1H NMR
(400 MHz, CDCl3): d=7.33–7.28 (2H, m), 6.86 (1H, dd, J=
6.8, 2.4 Hz), 5.85 (1H, dq, J=6.4, 2.0 Hz), 3.82 (3H, s),
3.78(1H, d, J=6.8 Hz), 2.57 (1H, brs), 2.33 (3H, d, J=
1.6 Hz), 1.41 (3H, s); 13C NMR (100 MHz, CDCl3): d=
157.1, 144.2, 139.3, 130.1, 121.5, 119.1, 117.4, 111.9, 73.7,
64.9, 55.7, 26.4, 23.9; ESI-MS: m/z=245.1110 ([M]+); calcd.
for C13H15N3O2: 245.1159
This work was supported by Grand-in-Aid for Young Scien-
tists (B) from the Japan Society for the Promotion of Science
(JSPS) and Ritsumeikan Global Innovation Research Organ-
ization (R-GIRO) project.
cis-2-Azido-1,4-dimethyl-5,7-dimethoxy-1-hydroxy-1,2-di-
hydronaphthalene (9i): light yellow oil; IR (ATR): n=3477,
2965, 2929, 2837, 2103, 1600, 1574, 1519, 1457, 1420, 1364,
1320, 1280, 1232, 1205, 1150, 1087, 1044, 973, 946, 897, 830,
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526
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 517 – 528

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Adv. Synth. Catal. 2013, 355, 517 – 528
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FULL PAPERS
position after the ring-opening of 1,4-dimethyl-1,4-
epoxy-1,4-dihydronaphthalenes, see refs.[1b,c,e]
[17] The relative configurations of 4c and 4i were deter-
mined by nOe experiments.
[18] Quite a few Rh-catalyzed regioselective substitutions
of unsymmetrical substrates bearing some functionali-
ties on the aromatic ring have been reported, see
refs.[7c,8f]
product was never observed even under AuCl3 and
AgSbF6-catalyzed conditions.
[24] a) Z. Rappoport, The Chemistry of the Cyano Group,
Interscience Publishers, London, 1970; b) R. C. Larock,
Comprehensive Organic Transformations. A Guide to
Functional Group Preparations, VCH Publishers, New
York, 1989.
[25] Other gold catalysts and traditional Lewis acids were
less reactive to the ring-opening cyanation of 1c.
[26] E. F. V. Scriven, Chem. Rev. 1988, 88, 297–368.
[27] Representative reports are cited, see; a) R. Huisgen,
Angew. Chem. 1963, 75, 604–637; Angew. Chem. Int.
Ed. Engl. 1963, 2, 565–598; b) V. V. Rostovsev, L. G.
Green, V. V. Fokin, K. B. Sharpless, Angew. Chem.
2002, 114, 2708–2711; Angew. Chem. Int. Ed. 2002, 41,
2596–2599.
[28] Azidations were all investigated using FeCl3 and ZnCl2
as Lewis acids. The better results are shown in Table 7.
[29] The reaction using 1,4-diphenyl-1,4-epoxy-1,4-dihydro-
naphthalene as a substrate provided 2,4-diphenyl-1-
naphthol without the nucleophilic additions due to the
quite high migration activity of the phenyl group. On
the other hand, the reaction of 1,4-bis(hydroxymethyl)-
1,4-epoxy-1,4-dihydronaphthalene and its derivatives
gave the complex mixture or undesired products with-
out the nucleophilic addition.
[19] The regiochemistry of products obtained by the ring-
opening functionalizations of the unsymmerical sub-
strates were determined by nOe experiments.
[20] In this literature, the R1 and R2 groups in substrates 1d-
l were respectively expressed as distal and proximal
substituents on the basis of the distance from the dihy-
drobenzene ring as depicted in ref.[4c]
[21] The relative configuration of 4k could not be deter-
mined by the nOe analysis.
[22] Some examples of the formation of the cycloadducts
due to the nucleophilic trap of the b-silylcations: a) K.
Nishitani, Y. Harada, Y. Nakamura, K. Yokoo, K. Ya-
makawa, Tetrahedron Lett. 1994, 35, 7809–7812; b) Y.
Sugita, Y. Kimura, I. Yokoe, Tetrahedron Lett. 1999, 40,
5877–5880; c) S. R. Angle, D. S. Belanger, N. A. El-
Said, J. Org. Chem. 2002, 67, 7699–7705.
[23] The stabilities of tri- or tetracyclic tetrahydrofuran de-
rivatives (4c, j, k and 7d) were strongly substrate-domi-
nated. Especially, 7d was stable under the acidic condi-
tions and the formation of the corresponding allylated
[30] Highly conjugated napththale ring might facilitate the
aromatization of the intermediate of the azidated reac-
tion to form 10k.
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