Gold(I)-catalyzed double migration cascades toward (1E,3E)-dienes and naphthalenes

Article abstract of DOI:10.1016/j.tet.2008.10.109

A novel gold(I)-catalyzed cascade cycloisomerization of a variety of propargylic esters leading to unsymmetrically substituted naphthalenes has been developed. This domino process involves an unprecedented tandem sequence of 1,3- and 1,2-migrations of two

Full text of DOI:10.1016/j.tet.2008.10.109

Tetrahedron 65 (2009) 1859–1870
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Gold(I)-catalyzed double migration cascades toward (1E,3E)-dienes
and naphthalenes
*
Alexander S. Dudnik, Todd Schwier, Vladimir Gevorgyan
Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, IL 60607-7061, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 30 July 2008
Received in revised form 23 October 2008
Accepted 24 October 2008
Available online 24 December 2008
A novel gold(I)-catalyzed cascade cycloisomerization of a variety of propargylic esters leading to un-
symmetrically substituted naphthalenes has been developed. This domino process involves an un-
precedented tandem sequence of 1,3- and 1,2-migrations of two substantially different migrating groups.
It is believed that this transformation proceeds via formation of 1,3-diene intermediate or its equivalent,
which, upon carbocyclization and aromatization steps, transforms into the naphthalene skeleton. In
addition, it was also demonstrated that a variety of 1,3-dienes can be accessed stereoselectively via the
1,3-migration–proton transfer cascade.
Keywords:
Gold
Propargylic esters
1,3-Dienes
Naphthalenes
Ó 2008 Elsevier Ltd. All rights reserved.
R3
1. Introduction
[Au]-cat
R2
OC(O)R3
Z
E
O
O
ð2Þ
ð3Þ
R1
80 °C
In recent years, gold catalysis received much attention.1 Partic-
ularly, increasing employment of gold catalysis in the cascade
transformations of propargylic esters2 led to the development of
diverse and versatile synthetic methods. Remarkable propensity of
propargylic esters to undergo formal 1,3-acyl migration1,2 through
the formation of activated allene equivalent allowed for efficient
and expeditious assembly of various acyclic unsaturated synthons3
and complex carbo-4 and heterocycles.5 Recently, two stereo-
selective Au(I)-catalyzed cascade isomerizations of propargylic
esters into 1,3-dienes,6 proceeding via a 1,3-migration–silicon
elimination7 (Eq. 1) or double 1,2-migration8 (Eq. 2) tandems, have
been reported. In addition, several protocols utilizing gold-cata-
lyzed transformations of propargylic9 (Eq. 3) or related allenyl-10
and homopropargylic11 systems (Eqs. 4 and 5) toward assembly of
polysubstituted benzene ring have been developed. Generally,
these benzannulation cascades proceed via initial carbocyclization
followed by elimination step.
R1
1,2-/1,2-H~
R2
R1
R1
[Au]-cat
rt
( )n
( )n
Hydrovinylation/
Elimination
R2
HO
R2
H
R4(O)CO R3
R2
R3
[Au]-cat
rt
OBn
R2
R1
OBn
ð4Þ
ð5Þ
R1
R3
OAc
R2
[Au]-cat
[Au]-cat
60 °C
OC(O)R3
rt
R3
O
O
E
ð1Þ
R1
AcO
R1
R1
1,3~ /
Si-elimination
OR4
1,3~ /
Elimination
R1
R3
SiMe3
R2
In line of our continuing effort on the development of novel
transition metal-catalyzed protocols toward carbo- and heterocy-
cles involving 1,3- or 1,2-migration steps,5d,e,12 we aimed at the
* Corresponding author. Tel.: þ1 312 355 3579; fax: þ1 312 355 0836.
E-mail address: vlad@uic.edu (V. Gevorgyan).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.10.109

1860
A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
X
to the formation of expected allene 4a in 73% yield (entry 1). Re-
X
OXO
H MG
O
O
O
O
R2
R1
markably, more electrophilic Au(I) triflate afforded target 1,3-diene
2a, a product of two formal 1,3-migrations, in 86% yield as a sole
(1E,3E)-isomer (entry 2). However, employment of Au(III) com-
plexes (entries 3 and 4), Au(I) halides (entries 5 and 6), Cu(I) and
Cu(II) triflates, as well as Brønsted or Lewis acids, resulted in no
reaction.
Next, isomerization of differently substituted propargylic esters
1a–g was examined under optimized conditions (Table 2). Thus,
the cascade transformation of propargylic esters 1a, 1c, and 1d
possessing various 1,3-migrating groups, such as phosphatyloxy-
(entry 1), acetyloxy- (entry 3), and pivaloxy- (entry 4), occurred
highly stereoselectively, affording the corresponding (1E,3E)-di-
enes 2a, 2c, and 2d in good to high yields. It was found that
R2
[Au]
R2
R1
1,3~
1,2~
R1
[Au]
MG [Au]
MG
1
- [Au]
MG
R2
R1 = Ph
- HOXO
MG
R2
OXO
R1
3
2
Scheme 1. Proposed Au-catalyzed double migration cascade.
designing a cascade transformation of propargylic systems pro-
ceeding via tandem 1,3- and 1,2-migration processes of two dif-
ferent migrating groups. Thus, we have developed two novel
gold(I)-catalyzed protocols for the expeditious assembly of multi-
substituted napthalenes13 and stereoselective synthesis of (1E,3E)-
dienes.14 Depending on the substitution pattern, propargylic esters
underwent 1,3-/1,2-migration-benzannulation cascade into naph-
thalenes13 or 1,3-migration/proton transfer tandem toward 1,3-di-
enes. Herein, we summarize our recent developments in this area,
and provide more detailed discussion on the scope and mecha-
nisms of these novel cascade transformations.
isomerization of
and 6), as well as
substrates proceeded nearly equally efficient, providing the cor-
responding 1,3-dienes 2b, 2e, 2f, and 2g in good to high yields.
However, isomerization of phosphates 1b and 1e, un-
b
-dialkyl- (entries 5 and 7), alkyl-aryl (entries 2
b
-diaryl- and -alkyl- (entry 6) substituted
a
symmetrically substituted at the
minished stereoselectivity (entries 2 and 5).
b-position, proceeded with di-
It should be noted that the analogous isomerization of prop-
argylic acetates 1 into 1,3-dienes 2 in the presence of cationic Ag
catalysts at elevated temperatures has been reported20 (Eq. 6). Al-
though, this cascade reaction was proposed to proceed via allene
intermediate 4, the entire mechanism of this transformation
2. Results and discussion
Table 2
Gold(I)-catalyzed synthesis of 1,3-dienes
2.1. Mild and stereoselective synthesis of 1,3-dienes
R2
R3
H
OXO
R3
2.5 mol%
Ph3PAuOTf
R2 E
R1
E
We anticipated that upon coordination of a cationic gold(I)
complex to the triple bond of propargylic ester 1, the latter would
undergo a formal 1,3-acyloxy- or phosphatyloxy-group migration
through the cyclic intermediate i (Scheme 1). Considering electro-
philic nature of the sp3-center2b in intermediate i, we envisioned
that incorporation of a suitable 1,2-migrating group (MG) in i
would provoke a subsequent 1,2-shift15,16 to give ii which, upon
proton transfer via proton loss–protiodeauration sequence, would
afford 1,3-diene 2. It was reasonable to propose that the latter may
R1
OXO
0.05M in
DCM, rt
1
H
2
Entry
1
Substrate
OP(O)(OEt)2
Product
Yield,a
%
Ph
Ph
1a
2a 83
OP(O)(OEt)2
OP(O)(OEt)2
OP(O)(OEt)2
undergo 6p-electrocyclization–elimination cascade into naphtha-
Ph
2
1b
2b 69b,c
lene17,18 2, analogously to the known carbocyclization of oxy-1,3,5-
Ph
Me
trienes19 (Scheme 1). To this end, a possible isomerization of
Me
Ph
propargyl phosphate 1a, possessing b-hydrogen atom as the 1,2-
migrating group, has been examined in the presence of different
catalysts (Table 1). It was found that employment of Ag triflate led
OAc
Ph
Ph
3
4
1c
2c 79
2d 86
OAc
OPiv
Ph
1d
Table 1
OPiv
Optimization of reaction conditions
Ph
OP(O)(OEt)2
OP(O)(OEt)
OP(O)(OEt)2
OP(O)(OEt)2
2
4a
2a
[Cat]
Et
Ph
1a
OP(O)(OEt)2
Et
5
6
1e
1f
2e 75b,d
or
0.05M in
DCM, rt
Me
Ph
Me
E
E
Entry
Catalyst
10% AgOTf
5% Ph3PAuCl, 5% AgOTf
5% AuCl3
5% AuCl3, 15% AgOTf
5% AuI
Time, h
Yield 4a,a
%
Yield 2a,a
%
2f 70
Ph
OAc
OAc
1
2
3
4
5
6
7
8
9
10
12
1
73
0
0
0
0
0
0
0
0
0
0
86
0
0
0
0
0
0
0
Ph
24
24
24
24
24
24
24
24
OP(O)(OEt)2
OP(O)(OEt)2
7
1g
2g 82e
5% R3PAuCl (R¼Et, Ph)
10% [CuOTf]2$PhH
10% Cu(OTf)2
a
Isolated yield; 0.5 mmol scale.
Au catalyst (5 mol %) was used.
Mixture of 4.3:1 (1E,3E)/(1E,3Z)-dienes.
Mixture of 1.3:1 (1E,3E)/(1E,3Z)-dienes.
Au catalyst (7.5 mol %) was used.
20% TMSOTf b
20% TfOHb
b
c
0
a
d
e
Isolated yield of product for reaction performed on 0.1–0.2 mmol scale.
Compound 1a decomposes at elevated temperatures in the presence of catalyst.
b

A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
1861
H(D) H(D)
remained unclear. In order to elucidate the mechanism of this
OP(O)(OEt)2
R1
R1
3
R1
D
5-7% Ph3PAu X
DCM, rt, 8-20h
transformation under Au(I)-catalysis, we first examined whether
the Au(I)-catalyzed cascade isomerization of phosphatyloxy-
substituted substrate 1a (MG¼H) involved formation of the allene
intermediate. Careful 1H NMR and GC–MS monitoring of the re-
action course at early stages revealed that the corresponding allene
intermediate 4a was initially formed and then completely iso-
merized into (1E,3E)-diene 2a (Eq. 7). In addition, independently
prepared phosphatyloxyallene 4a was quantitatively transformed
into 1,3-diene 2a in the presence of Au(I) triflate (Eq. 8). Finally, our
D-labeling studies on the isomerization of propargylic phosphate
1a-d ruled out possible involvement of alkyne–vinylidene isomer-
ization,21 thus, strongly supporting 1,3-migration path22 (Eq. 9).
1
OP(O)(OEt)2
2
R1
H(D)
2h-dn
2i-dn
R1 = Me; 93% D
1h-d:
1i-d: R1 = Ph; 77% D
d1-% d2-% d3-%
X
Yield
65%
64%
2h-dn
2i-dn
27
10
21
33
<2
0
OTf
<3
0
29
13
16
25
40% 2h-dn
89%
SbF6
BF4
2i-dn
2h-dn
2i-dn
-
-
-
-
0
28
88%
17
ð11Þ
R3
R2
We propose the following mechanism for the cascade trans-
formation of propargylic esters 1 into 1,3-dienes 2 (Scheme 2). First,
propargyl ester 1 undergoes Au(I)-catalyzed 1,3-migration27 of
R3
R2 R1
H
OAc
E
E
[Ag]
R2
R1
[Ag]
OAc
H
ð6Þ
R1
OAc
80 °C
80 °C
R3
1
4
2
R1 R2
R2
R2
R1
H
O
LAu
1,3-OXO~
O
R1
H
X
OP(O)(OEt)2
X
OP(O)(OEt)2
2.5%
Ph3PAuOTf
DCM, rt
Ph
-H
E
O
OXO
O
LAu
LAu
LAu
LAu
2a
4a
E
1a
Ph
OP(O)(OEt)2
1
Ph
86%
- LAu
+ H
- LAu
observed by GC-MS and NMR
X = CR; P(OEt)2
R2
R1
E
E
R2
ð7Þ
OXO
OXO
H
R1
4
2
H
10% AgOTf
DCM, rt
Scheme 2. Mechanistic rationale for Au(I)-catalyzed synthesis of 1,3-dienes.
5%
Ph3PAuOTf
>99%
ð8Þ
Ph
1a
2a
OP(O)(OEt)2
73%
4a
acyloxy- or phosphatyloxy-group to give cyclic intermediate iii
which, upon elimination of Au(I) catalyst, produces allene in-
termediate 3. A direct elimination of the b-proton from iii produces
a vinyl gold intermediate iv, which upon protiodeauration furnishes
1,3-diene 2 and regenerates the Au(I) catalyst (Scheme 2).
D 99%
E
OP(O)(OEt)2
E
5% Ph3PAuOTf
0.05M in DCM,
rt, 1.5h
Ph
Ph
OP(O)(OEt)2
99+%
D
2a-d
77%
1a-d
2.2. Synthesis of naphthalenes
ð9Þ
In light of the recent observations that eventual Brønsted acids
Targeting at the development of 1,3-/1,2-double migration tan-
dem, we hypothesized that successful incorporation of a 1,2-shift
into this cascade can only be achieved when a 1,2-migrating group
resides at a ‘proton-free’ quaternary C-4 center.16 Accordingly,
isomerization of acetate 1j, possessing strained cyclobutane ring,
was examined. Gratifyingly, a tandem 1,3-migration and the ring
expansion via a 1,2-alkyl shift occurred furnishing 1,3-diene 2j in
54% yield (Eq. 12). Moreover, cyclopentyl-substituted analogs 1k
and 1l underwent further cycloisomerization with ring expansion
to give the benzannulation products, naphthalenes 3k and 3l, re-
spectively (Eq. 13), thus providing a proof of concept for this cas-
cade transformation.28
are the true catalysts in some transition metal-catalyzed trans-
formations,23 we investigated what role, if any, Brønsted or Lewis
acids may play in the herein described isomerization reaction.
Accordingly, our optimization studies (Table 1, entries 9 and 10)
revealed that isomerization of propargyl phosphate 1a in the
presence of TfOH or TMSOTf provided no 1,3-diene 2a. In addition,
it was found that isomerization of allene 4a in the presence of
Brønsted or Lewis acids even at elevated temperatures provided
trace amounts of 2a only (Eq. 10).
20% TMSOTf
E
E
Ph
or HOTf
Ph
OP(O)(OEt)2
OP(O)(OEt)2
traces
DCE, rt or
100 °C
AcO
4a
2a
10% Ph3PAuOTf
E
ð12Þ
ð10Þ
DCE, rt
54%
Ph
Ph
1j
2j
OAc
Aiming at distinguishing the nature of elementary processes in
the second step, isomerization of D-labeled phosphates 1h-d and
1i-d was investigated in the presence of different cationic Au(I)
catalysts. It was found that, along with significant loss of deute-
rium label,24 the latter was scrambled between C-1 and C-2 in the
corresponding 1,3-dienes 2h-dn and 2i-dn (Eq. 11).25 In addition,
the nature of the counteranion at Au(I) complex did not signifi-
cantly affect distribution of D-label in 1,3-diene products.26 Most
importantly, absence of a deuterium label at C-3 strongly in-
dicated exclusive involvement of the proton elimination at the
second step.
AcO
10% Ph3PAuOTf
DCE, rt
R1
Ph
1
3
R1
ð13Þ
R1 Isolated yield, %
Product
3k
H
n-Hex
36
30
3l

1862
A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
phosphate 1o was less facile than that of analogous acetate 1n,
Next, the scope of this cascade transformation was examined
likely due to the increased steric hindrance (entry 3 vs 2). Notably,
a variety of substituents, such as methoxy (entry 6), trifluoromethyl
(entry 7), and 2-furyl (entry 8), were perfectly tolerated under the
reaction conditions. Unexpectedly, cycloizomerization of dime-
thylphenyl-substituted acetate 1q proceeded via exclusive 1,2-Me-
over 1,2-Ph-group migration to give naphthalene 3q in 73% yield
(entry 5). In contrast, diphenylmethyl-substituted propargylic ester
(Table 3). It was found that propargylic esters 1m–p and 1r–u
smoothly underwent a tandem acyloxy- or phosphatyloxy- and Ph-
group migration/benzannulation cascade to provide naphthalenes
3m–p and 3r–u in good to excellent yields (entries 1–4 and 6–9).
Terminal, as well as alkyl- and aryl-substituted propargylic sub-
strates were nearly equally efficient in this cascade transformation
(entry 1 vs entries 2 and 4). However, isomerization of nonterminal
Table 3
Gold(I)-catalyzed synthesis of naphthalenes
R1
H
OXO
R3
R2
10% Ar3PAuX
0.05M in DCE, rt
R2
R1 Ph
R3
1
3
Entry
1
Substrate
Catalysta
A
Product
Yield,b,c
86d
%
Ph
OP(O)(OEt)2
Ph
Ph
Ph
3m
3n
3n
Ph
OAc
Ph
Ph
Ph
Ph
Ph
Ph
2
3
A
A
94
50
Ph
OP(O)(OEt)2
Bu-n
Bu-n
Ph
Ph
Ph
Ph
Bu-n
Bu-n
Ph
OAc
Ph
Ph
4
5
A
A
3p
3q
75
73
Ph
Ph
Ph
Me
Ph
OAc
Me
Me
Me
Ph
AcO
Ph
6
7
A
A
3r
3s
90
84
Ph
Ph
OMe
Ph
C6H4-p-OMe
Ph
Ph
AcO
Ph
Ph
CF3
Ph
C6H4-p-CF3
Ph
Ph
AcO
Ph
8
9
A
A
3t
94
51
Ph
Ph
O
O
Me
OAc
Ph
Me
Ph
3u
Ph
Me
Me
Ph
OAc
Me
Me
10
B
3v
57
Ph
Ph

A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
1863
Table 3 (continued )
Entry
Substrate
Catalysta
Product
Yield,b,c
%
Me
Me
OAc
Me
Me
11
12
13
B
3w
3k
3l
77
96
75
Ph
Bu-n
Bu-n
OAc
B
B
Ph
OAc
Ph
Hex-n
Hex-n
OAc
14
B
3x
74
Ph
a
Catalyst A¼Ph3PAuOTf; catalyst B¼(F5C6)3PAuSbF6.
Isolated yield.
Reactions were performed on 0.5 mmol scale.
Au catalyst (5%) was used.
b
c
d
1u exhibited normal Ph- versus Me-group migratory aptitude upon
gold catalysis, providing 1-methyl-2-phenylnaphthalene 3u as
a sole regiosomer via exclusive 1,2-Ph-group migration (entry 9).
Moreover, the scope of 1,2-migrating groups was further extended
with the employment of a truly cationic (F5C6)3PAuSbF6 catalyst.
Thus, a variety of alkyl- and cycloalkyl-substituted substrates 1k, 1l,
and 1v–x possessing terminal, as well as internal alkyne moiety,
readily underwent migrative benzannulation cascade to give the
corresponding polysubstituted naphthalenes in good to excellent
yields (entries 10–14).
We propose the following plausible mechanisms for this
cascade cycloisomerization (Scheme 3). The Au(I)-catalyzed
1,3-acyloxy- or 1,3-phosphatyloxy-group migration transforms
propargylic ester 1 via cyclic intermediate2b,3c,5b v into allenyl in-
termediate 4. According to the path A, intermediate v undergoes
a 1,2-alkyl migration29 to give benzylic cation vi. The latter, upon
proton transfer produces oxonium intermediate vii, which upon
reversible elimination of Au(I) catalyst furnishes 1,3-diene in-
termediate 2. The direct Friedel–Crafts alkylation in vii, followed by
the aromatization and loss of Au(I) catalyst, affords naphthalene
3.30 In another scenario (path B), a direct nucleophilic attack of
nucleophilic vinyl–Au moiety at the delocalized benzyl cation in
vi31 produces Au–carbenoid intermediate viii, which upon 1,2-hy-
dride shift32 and aromatization steps gives naphthalene 3. Alter-
R2
R2
Ph
O
R1
H
X
R1
LAu
LAu
O
1
X = CMe; P(OEt)2
L = Ar3P
Ph
R3
OXO
2
R3
1,3-OXO~
+LAu
R2
-LAu
natively,
a
direct intramolecular hydroarylation of allenyl
R2
H
X
intermediate 4, followed by 1,2-shift induced by Au(I) catalyst and
proton loss in x, produces 3 (path C). Path B involving carbocycli-
zation of [1,6]-Au-dipole11 with concomitant 1,2-hydride shift to
Au–carbenoid center was not supported by the observed significant
loss of D-label during the cycloisomerization of a labeled acetate
1p-d (Eq. 14). In addition, employment of more cationic Au(I) cat-
alyst with noncoordinating hexafluoroantimonate counteranion
led to even more pronounced loss of deuterium label in 4p-
d compared to that for triflate (Eq. 14).
Proton
H
O
O
AuL
R1
AuL
OXO
R1
1,2-R2~
transfer
H
R3
R3
Ph
R1
R3
AuL
OXO
R2
+LAu
-LAu
Path B
Path A
R1 R2
R2
H
H
-LAu
R1
AuL
-H OXO
Ph
Ph
Ph
96+%
R3
OXO
4
AcO
D
R3
10% Ph3PAuX
OXO
H
D
Ph3C
-LAu
0.05M
-H
OXO
Ph
DCE, rt
Path C
ð14Þ
LAu
1p-d
3p-d
R1
R2
3
X
OTf
SbF6
Yield
D-inc,%
33
20
H
H
R2
R1
R2
R1
Proton
78%
94%
AuL
OXO
H
transfer
OXO
R3
R3
-LAu
-LAu
OXO
R3
H
AuL
-H
In order to get an additional support for the involvement of
Scheme 3. Mechanistic rationale for Au(I)-catalyzed synthesis of naphthalenes.
proposed allene 4 and 1,3-diene 2 intermediates in this cascade

1864
A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
process, we performed several mechanistic studies on cyclo-
isomerization of propargylic phosphates and acetates. Our careful
GC–MS monitoring of the reaction course at initial stages revealed
that propargylic phosphate 1m underwent facile 1,3-phosphatyl-
oxy group migration to give the corresponding allene intermediate
4m, which then was completely cycloisomerized into naphthalene
3m (Eq. 15). In addition, independently prepared phosphatyloxy-
allene 4m can be cycloisomerized into naphthalene 3m with the
same efficiency in the presence of Au(I) triflate. Furthermore, suc-
cessful cycloisomerization of 1,3-diene 2f, obtained via a 1,3-mi-
gration/proton transfer tandem, into naphthalene 3k provided an
additional support for possible intermediacy of 1,3-dienes in this
transformation (Eq. 16).33
migratory aptitudes’ are exhibited (Scheme 5). On the other hand,
reversible 1,2-migration leading to the more stable intermediate
benzylic carbocation under the thermodynamic control can also
account for the observed chemoselectivity.
Alternatively, exclusive Me- versus Ph-migration in dimethyl-
phenyl-substituted propargylic acetate 1q, as well as Ph- over Me-
migration in case of diphenylmethyl-substituted 1u, can also be
explained via path C, according to which 1,2-migration occurs after
cyclization step. Although path C cannot be completely ruled out at
this point, it is considered to be less likely since it cannot fully account
for the reactivities observed during cycloisomerization of cyclobutyl-
substituted propargylic ester 1j and benzannulation of 1,3-diene 2f.
3. Conclusions
Ph
Ph3C
5%
Ph3PAuOTf
(EtO)2P(O)O
Ph3C
Ph
Two novel Au(I)-catalyzed cascade processes for the synthesis of
multisubstituted 1,3-dienes and naphthalenes have been de-
0.05M
86%
4m
DCE, rt
OP(O)(OEt)2
observed by GC-MS
1m
3m
veloped. It was demonstrated that
b-unsubstituted propargylic
phosphates, acetates, and pivalates can undergo an exceptionally
mild and stereoselective Au(I)-catalyzed isomerization proceeding
via 1,3-migration/proton transfer cascade into the corresponding 1-
oxy-1,3-diene esters. Alternatively, a variety of densely substituted
naphthalenes can be accessed through the Au(I)-catalyzed cascade
ð15Þ
Ph
[Au]
5% Ph3PAuOTf
b-quaternary propargylic phosphates and
cycloisomerization of
acetates. This domino transformation involves an unprecedented
1,3-/1,2-migration cascade of two different migrating groups fol-
lowed by the benzannulation step. In addition, this mild protocol
allows for selective and highly efficient assembly of naphthalenes,
not available via existing methodologies.
70%
Ph
DCE, 60 °C
88%
OAc
OAc
1f
2f
3k
ð16Þ
Unexpected exclusive Me- over Ph-migration in dimethylphenyl-
substituted acetate 1q is reasonably rationalized by stereoelectronic
effect, according to which Ph-group cannot accommodate requisite
antiperiplanar orientationwith the leaving group in xi (Scheme 4).34
Therefore, migration of a methyl group is strongly favored to
4. Experimental
4.1. General
NMR spectra were recorded on Bruker Avance DRX-500
(500 MHz) and DPX-400 (400 MHz) instruments. GC–MS analyses
were performed on a Hewlett Packard Model 6890 GC interfaced
Me
Me
O
O
O
O
H
H
to
(15 mꢀ0.25 mm capillary column, HP-5MS). Column chromato-
graphy was carried out employing Silicycle silica gel (43–60 m).
a Hewlett Packard Model 5973 mass selective detector
H
H
Ph
H
Me
vs
Me
Me
H
Au
PPh3
Au
PPh3
m
H
HRMS (EI) analysis was performed on a JEOL GCmate II instrument.
All manipulations with transition metal catalysts were conducted
under inert atmosphere using a combination of glovebox and
standard Schlenk techniques. Anhydrous toluene, tetrahydrofuran,
dichloromethane, and 1,2-dichloroethane purchased from Aldrich
were additionally purified on PureSolv PS-400-4 by Innovative
Technology, Inc. purification system. All other chemicals and sol-
vents were purchased from Aldrich, Fisher, Acros Organics, TCI, and
Alfa Aesar and used without additional purification.
Scheme 4. Stereoelectronic models for cycloisomerization of 1q.
proceed via a conformationally more stable intermediate xii
(Scheme 4). The same trend is observed for cycloisomerization of
cycloalkylphenyl-substituted substrates where the migratory apti-
tudes are controlled by the stereoelectronic requirements in a cyclic-
type intermediate v (Scheme 3). It is believed that in case of bulkier
diphenylmethyl- and triphenyl-substituted propargylic esters,
required antiperiplanar orientation cannot be adopted by any of
migrating groups due to repulsion of phenyl rings with the 1,3-
dioxenium core (xiii). Accordingly,1,2-migration in these cases most
likely proceeds through the less stable open enonium intermediate
xiv where steric interactions are insignificant and, thus, ‘normal
4.2. General procedures for the synthesis of propargyl
acetates and phosphates
4.2.1. Procedure A
Neat carbonyl compound (or its solution in 15 ml of anhydrous
THF) (33 mmol) was added dropwise to an ice cooled flask con-
taining 60 ml of 0.55 M solution of ethynylmagnesium bromide in
THF (33 mmol) while stirring. After addition the reaction mixture
was allowed to warm to room temperature and stirred for an ad-
ditional 1 h. Reaction mixture was placed then in the ice-water bath
and 39.6 mmol of neat diethylchlorophosphate (5.69 ml) or acetic
anhydride (3.74 ml) was added dropwise. Reaction mixture was
allowed to warm to room temperature and was stirred until judged
complete by TLC and GC analyses. After completion, reaction mix-
ture was poured into 250 ml of saturated ammonium chloride
solution and extracted three times with ethyl acetate (150 ml).
Me
PPh3
Au
O
O
H
H
H
O
vs
Me
H
Au
PPh3
O
Scheme 5. 1,2-Migration models for trityl-substituted propargylic esters.

A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
1865
Combined organic extracts were dried over anhydrous sodium
sulfate. Solvents were removed under reduced pressure and the
residue was purified by column chromatography (EtOAc/Hex) to
give the corresponding propargyl acetate or phosphate.
5H), 5.02–5.08 (m, 1H), 3.91–4.10 (m, 4H), 3.14–3.22 (m, 1H), 2.52
(d, J¼2.20 Hz, 1H), 1.43 (d, J¼7.15 Hz, 3H), 1.22–1.29 (m, 6H); 13C
NMR (126 MHz, CDCl3) d 140.93, 128.31, 128.19, 127.09, 80.02, 75.95,
71.81, 71.76, 63.91, 63.86, 63.81, 63.76, 44.89, 44.84, 16.04.
4.2.2. Procedure B
4.2.3.3. 1-Benzylprop-2-yn-1-yl acetate (1c). Yield 67% (procedure
To the cooled ꢁ78 ꢂC flask containing 25 ml of anhydrous THF
was added 15 mmol of neat terminal acetylene, followed by drop-
wise addition of 5.8 ml of 2.61 M solution of n-BuLi in hexanes
(15 mmol). The reaction mixture was allowed to warm to room
temperature allowing for formation of ca. 0.5 M solution of corre-
sponding alkynyllithium in THF. After cooling to ꢁ78 ꢂC,15 mmol of
carbonyl compound was added dropwise. Reaction mixture was
allowed to warm to room temperature and cooled back to ꢁ78 ꢂC;
18 mmol of neat diethylchlorophosphate (2.6 ml) or acetic anhy-
dride (1.7 ml) was added to the reaction mixture dropwise. After
warming up, reaction mixture was stirred at room temperature
until judged complete by TLC and GC analyses. Reaction mixture
was poured into 250 ml of saturated ammonium chloride solution
and extracted three times with ethyl acetate (150 ml). Combined
organic extracts were dried over anhydrous sodium sulfate. Sol-
vents were removed under reduced pressure and the residue was
purified by column chromatography (EtOAc/Hex) to give the cor-
responding propargyl acetate or phosphate.
A). 1H NMR (400 MHz, CDCl3)
d
7.22–7.36 (m, 5H), 5.54 (dt, J¼6.83,
2.12 Hz, 1H), 3.09 (dd, J¼6.87, 3.07 Hz, 2H), 2.47 (d, J¼2.19 Hz, 1H),
2.06 (s, 3H); 13C NMR (101 MHz, CDCl3)
169.75, 135.64, 129.65,
d
128.38, 127.08, 80.70, 74.38, 64.30, 40.95, 20.93.
4.2.3.4. 1-Benzylprop-2-yn-1-yl pivalate (1d). Yield 58% (procedure
A). 1H NMR (500 MHz, CDCl3)
d
7.22–7.33 (m, 5H), 5.51 (dt, J¼6.88,
2.20 Hz, 1H), 3.10 (d, J¼6.97 Hz, 2H), 2.44 (d, J¼2.02 Hz, 1H), 1.15 (s,
9H); 13C NMR (126 MHz, CDCl3)
177.14, 135.83, 129.65, 128.27,
d
126.97, 80.98, 73.90, 63.99, 40.98, 38.65, 26.95.
4.2.3.5. Diethyl 1-ethynyl-2-methylbutyl phosphate (1e). Yield 59%
(procedure A). 1H NMR (500 MHz, CDCl3)
d
4.86–4.93 (m, J¼12.33,
7.34, 5.09, 2.20 Hz, 1H), 4.07–4.18 (m, 4H), 2.53 (dd, J¼3.30, 2.20 Hz,
1H), 1.72–1.86 (m, 1H), 1.48–1.70 (m, 1H), 1.31–1.36 (m, 6H), 1.21–
1.31 (m, 1H), 1.02 (dd, J¼6.79, 5.69 Hz, 3H), 0.92 (td, J¼7.47, 4.13 Hz,
3H); 13C NMR (126 MHz, CDCl3)
d 80.23, 79.54, 75.39, 75.09, 71.73,
71.69, 71.59, 71.54, 63.93, 63.88, 63.82, 63.78, 40.49, 40.45, 40.12,
40.08, 25.07, 24.39, 16.05, 14.42, 13.85, 11.44, 11.32.
4.2.3. Procedure C
To a solution of 8.6 mmol of triphenylacetaldehyde in 10 mL
anhydrous THF was added 26 mL of a 0.5 M solution of ethy-
nylmagnesium bromide in THF (13 mmol) while stirring. After ad-
dition the reaction mixture was allowed to warm to room
temperature and stirred for an additional 1 h. The reaction mixture
was poured into 50 mL of 2 M HCl(aq) and extracted three times
with ethyl acetate. The combined organic phases were dried over
anhydrous magnesium sulfate, filtered, and concentrated. The
material was filtered through silica (2:1 hexanes/ethyl acetate as
eluent) to give 2.57 g (quant.) of material of >98% purity (as judged
by NMR analysis). To a 5 ml Wheaton V-vial charged with 3 mol %
PdCl2(PPh3)2 and 5 mol % CuI, under N2 atmosphere, was added
1 mmol of the propargyl alcohol. The vial was equipped with
a Teflon septa and cap and 2 mL of anhydrous triethylamine was
added. The appropriate aryl bromide was added and the reaction
mixture heated to 80 ꢂC for several hours, until TLC analysis
showed consumption of the starting material. The reaction mixture
was filtered through a short silica plug with ethyl acetate and
concentrated. The crude material was redissolved in 2 mL anhy-
drous pyridine and 2 mmol dimethylaminopyridine was added at
once. Acetyl chloride (2 mmol) was then added dropwise and the
reaction mixture was stirred for several hours. When TLC analysis
showed the reaction had completed, the reaction mixture was
poured into 20 mL of 2 M HCl(aq) and extracted three times with
ethyl acetate. The combined organic phases were dried over an-
hydrous magnesium sulfate, filtered, and concentrated. The residue
was purified by column chromatography (silica, 3:1 hexanes/ethyl
acetate).
4.2.3.6. 1-Ethynyl-2-phenylcyclohexyl acetate (1f). Yield 71% (pro-
cedure A). Isolated as a 1.3:1 mixture of diastereomers. 1H NMR
(500 MHz, CDCl3)
d 7.34–7.40 (m, 2H), 7.23–7.34 (m, 3H), 3.07–
3.13 (m, 0.58H), 3.05 (dd, J¼13.0, 3.1 Hz, 0.48H), 2.84–2.90 (m,
0.45H), 2.76 (dd, J¼12.8, 3.7 Hz, 0.59H), 2.68 (s, 0.35H), 2.45 (s,
0.46H), 2.02–2.23 (m, 1H), 2.09 (s, 1.73H), 1.91 (s, 1.25H), 1.59–1.90
(m, 5H), 1.34–1.54 (m, 1H); 13C NMR (126 MHz, CDCl3)
d 169.0,
168.9, 141.3, 140.5, 129.6, 129.5, 127.5, 127.4, 126.9, 83.2, 80.5, 79.8,
77.7, 75.7, 74.9, 53.5, 51.7, 35.4, 29.6, 27.9, 25.8, 25.6, 23.6, 21.9,
21.7, 20.7.
4.2.3.7. 1-Cyclohexylprop-2-yn-1-yl diethyl phosphate (1g). Yield
70% (procedure A). 1H NMR (500 MHz, CDCl3)
d 4.70–4.76 (m, 1H),
4.03–4.14 (m, 4H), 2.52 (dd, J¼2.20, 0.92 Hz, 1H), 1.60–1.85 (m, 6H),
1.26–1.32 (m, 6H), 1.03–1.24 (m, 5H); 13C NMR (126 MHz, CDCl3)
d
80.06, 80.04, 75.31, 72.00, 71.95, 63.88, 63.84, 63.80, 63.76, 43.04,
43.00, 28.09, 27.58, 26.10, 25.60, 25.56, 16.08, 16.03, 15.98.
4.2.3.8. 1-(1-Phenylcyclobutyl)prop-2-ynyl acetate (1j). Yield 86%
(procedure A). 1H NMR (500 MHz, CDCl3)
d 7.31–7.36 (m, 2H), 7.23–
7.28 (m, 3H), 5.66 (d, J¼2.0 Hz, 1H), 2.42–2.51 (m, 4H), 2.38 (d,
J¼2.0 Hz, 1H), 2.10–2.20 (m, 1H), 2.06 (s, 3H), 1.84–1.95 (m, 1H); 13C
NMR (126 MHz, CDCl3)
d 170.0, 144.8, 127.6, 127.3, 126.3, 79.3, 74.4,
69.5, 48.9, 30.1, 30.0, 20.8, 15.6.
4.2.3.9. 1-(1-Phenylcyclopentyl)prop-2-ynyl acetate (1k). Yield 96%
(procedure A). 1H NMR (500 MHz, CDCl3)
d 7.38–7.43 (m, 2H),
7.30–7.34 (m, 2H), 7.22–7.27 (m, 1H), 5.55 (d, J¼2.2 Hz, 1H), 2.36 (d,
J¼2.2 Hz, 1H), 2.18–2.26 (m, 1H), 2.09–2.18 (m, 2H), 2.03–2.08 (m,
1H), 2.02 (s, 3H), 1.74–1.84 (m, 2H), 1.62–1.73 (m, 2H); 13C NMR
4.2.3.1. Diethyl 1-phenylbut-3-yn-2-yl phosphate (1a). Yield 45%
(procedure A). 1H NMR (500 MHz, CDCl3)
d
7.19–7.37 (m, 5H), 5.15
(126 MHz, CDCl3) d 169.9, 143.6, 128.1, 127.7, 126.5, 79.9, 74.4, 69.3,
(dq, J¼7.20, 6.97, 2.11 Hz, 1H), 3.98–4.14 (m, 2H), 3.82–3.98 (m, 2H),
54.5, 34.8, 34.6, 23.8, 23.5, 20.8.
3.09–3.19 (m, 2H), 2.58 (d, J¼2.02 Hz, 1H), 1.29 (td, J¼7.11, 1.01 Hz,
3H),1.23 (td, J¼7.11,1.01 Hz, 3H); 13C NMR (126 MHz, CDCl3)
d
135.4,
4.2.3.10. 1-(1-Phenylcyclopentyl)non-2-ynyl acetate (1l). Yield 78%
129.8, 128.4, 127.1, 80.7, 75.5, 68.1 (d, JCP¼5.5 Hz), 63.93 (d,
JCP¼5.5 Hz), 63.78 (d, JCP¼5.5 Hz), 42.8 (d, JCP¼6.5 Hz), 16.0 (2C, d,
JCP¼5.5 Hz).
(procedure B). 1H NMR (500 MHz, CDCl3)
d 7.37–7.43 (m, 2H),
7.31 (t, J¼7.6 Hz, 2H), 7.23 (tt, J¼7.3, 1.1 Hz, 1H), 5.55 (t,
J¼2.0 Hz, 1H), 2.18–2.27 (m, 1H), 2.15 (td, J¼7.1, 2.0 Hz, 2H),
2.01–2.13 (m, 1H), 2.00 (s, 3H), 1.72–1.87 (m, 2H), 1.56–1.73 (m,
2H), 1.40–1.52 (m, 2H), 1.22–1.38 (m, 6H), 0.91 (t, J¼7.1 Hz, 3H);
4.2.3.2. Diethyl 1-(1-phenylethyl)prop-2-yn-1-yl phosphate (1b).
Yield 55% (procedure A). 1H NMR (500 MHz, CDCl3)
d
7.18–7.33 (m,
13C NMR (126 MHz, CDCl3)
d 70.0, 144.3, 128.1, 127.5, 126.2, 87.1,

1866
A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
76.3, 70.1, 54.9, 34.9, 34.7, 31.3, 28.5, 28.4, 23.9, 23.6, 22.5, 20.9,
18.7, 14.0.
1.95 (s, 3H),1.92 (s, 3H); 13C NMR (126 MHz, CDCl3)
d 169.65,145.26,
144.65, 128.12, 127.99, 127.86, 127.78, 126.50, 79.73, 75.74, 69.14,
50.54, 24.42, 20.76.
4.2.3.11. Diethyl 1,1,1-triphenylbut-3-yn-2-yl phosphate (1g). Yield
76%, (procedure A). 1H NMR (500 MHz, CDCl3)
d
7.32–7.36 (m, 6H),
4.2.3.20. 1-(1-Methyl-1-phenylethyl)-3-phenylprop-2-yn-1-yl ace-
7.25–7.31 (m, 6H), 7.20–7.25 (m, 3H), 6.39 (dd, J¼6.6, 2.2 Hz, 1H),
3.93–4.01 (quin d, J¼7.2, 0.9 Hz, 2H), 3.57–3.67 (quin, J¼7.2, 1H),
3.46–3.56 (m, 1H), 2.53 (d, J¼2.2 Hz, 1H), 1.22 (td, J¼7.1, 1.0 Hz, 3H),
tate (1v). Yield 75% (procedure B). 1H NMR (500 MHz, CDCl3)
d
7.44–7.51 (m, 2H), 7.22–7.41 (m, 8H), 5.80 (s, 1H), 2.01 (s, 3H), 1.56
(s, 3H), 1.55 (s, 3H); 13C NMR (126 MHz, CDCl3)
d
169.89, 144.88,
1.04 (td, J¼7.1, 1.0 Hz, 3H); 13C NMR (126 MHz, CDCl3)
d
143.3, 130.0,
131.84, 128.53, 128.22, 128.04, 126.64, 126.55, 122.39, 86.11, 85.34,
71.83, 42.34, 25.10, 23.98, 20.86.
127.6, 126.6, 80.3, 78.9, 72.4 (d, JCP¼6.5 Hz), 64.0 (d, JCP¼6.5 Hz),
63.6 (d, JCP¼5.5 Hz), 61.9 (d, JCP¼7.4 Hz), 15.9 (d, JCP¼6.5 Hz).
4.2.3.21. 1-(1-Methyl-1-phenylethyl)hept-2-yn-1-yl acetate (1w).
4.2.3.12. Diethyl 1,1,1-triphenyloct-3-yn-2-yl phosphate (1n). Yield
Yield 65% (procedure B). 1H NMR (500 MHz, CDCl3)
d 7.38–7.44 (m,
82% (procedure B).1H NMR (500 MHz, CDCl3)
d
7.33 (d, J¼7.5 Hz, 6H),
2H), 7.27–7.33 (m, 2H), 7.18–7.24 (m, 1H), 5.56 (t, J¼2.02 Hz, 1H),
2.16 (dt, J¼7.02, 1.93 Hz, 2H), 1.95 (s, 3H), 1.39–1.50 (ov. m, 8H),
1.29–1.37 (m, 2H), 0.88 (t, J¼7.34 Hz, 3H); 13C NMR (126 MHz,
7.23–7.30 (m, 6H), 7.16–7.23 (m, 3H), 6.35 (dt, J¼6.1, 2.0 Hz,1H), 3.87–
4.01 (m, 2H), 3.54–3.64 (m,1H), 3.43–3.52 (m,1H),1.96–2.09 (m, 2H),
1.21 (td, J¼7.1, 0.9 Hz, 3H), 1.15–1.23 (m, 2H), 1.04–1.13 (m, 2H), 1.02
(td, J¼7.1, 1.1 Hz, 3H), 0.75 (t, J¼7.2 Hz, 3H); 13C NMR (126 MHz,
CDCl3)
d 169.90, 145.17, 127.92, 126.54, 126.32, 87.05, 76.05, 71.79,
42.07, 30.51, 25.05, 23.84, 21.84, 20.85, 18.37, 13.58.
CDCl3)
d
143.8, 130.1, 127.4, 126.4, 91.6, 73.1 (d, JCP¼6.5 Hz), 63.7 (d,
JCP¼5.5 Hz), 63.3 (d, JCP¼5.5 Hz), 62.3 (d, JCP¼9.2 Hz), 30.0, 21.5,18.4,
4.2.3.22. 1-(1-Phenylcyclohexyl)prop-2-yn-1-yl acetate (1x). Yield
15.8 (d, JCP¼5.5 Hz), 15.9 (d, JCP¼5.5 Hz), 13.4.
97% (procedure A). 1H NMR (500 MHz, CDCl3)
d 7.41–7.45 (m, 2H),
7.31–7.38 (m, 2H), 7.22–7.26 (m, 1H), 5.36 (d, J¼2.20 Hz, 1H), 2.39
(d, J¼2.20 Hz, 1H), 2.31–2.43 (m, 2H), 1.97 (s, 3H), 1.70–1.81 (m, 2H),
1.52–1.64 (m, 3H), 1.24–1.37 (m, 3H); 13C NMR (126 MHz, CDCl3)
4.2.3.13. 1,1,1-Triphenyloct-3-yn-2-yl acetate (1o). Yield 82% (pro-
cedure B). 1H NMR (500 MHz, CDCl3)
d 7.18–7.33 (m, 15H), 6.74 (t,
J¼2.0 Hz, 1H), 1.99–2.05 (m, 2H), 1.85 (s, 3H), 1.17–1.25 (m, 2H),
d 169.64, 140.18, 128.42, 128.01, 126.46, 79.37, 74.98, 71.64, 45.56,
31.70, 31.00, 26.31, 21.79, 21.72, 20.73.
1.05–1.14 (m, 2H), 0.76 (t, J¼7.2 Hz, 3H); 13C NMR (126 MHz, CDCl3)
d
169.9, 144.2, 129.9, 127.5, 126.4, 89.9, 69.3, 61.5, 30.0, 21.5, 20.9,
18.3, 13.5.
4.2.3.23. 1-Benzylprop-2-yn-1-yl diethyl phosphate-d1 (1a-d). To
the cooled ꢁ78 ꢂC flask containing 3.5 ml of anhydrous THF was
added 288.3 mg (1 mmol) of neat acetylene 1a, followed by drop-
4.2.3.14. 1,1,1,4-Tetraphenylbut-3-yn-2-yl acetate (1p). Yield 74%
(procedure B). 1H NMR (500 MHz, CDCl3)
d
7.33–7.37 (m, 6H), 7.30 (t,
J¼7.4 Hz, 6H), 7.23–7.28 (m, 4H), 7.18–7.23 (m, 2H), 7.10–7.13 (m, 2H),
6.96 (s, 1H), 1.89 (s, 3H); 13C NMR (126 MHz, CDCl3)
169.8, 144.0,
wise addition of 384 ml of 2.61 M solution of n-BuLi in hexanes
(1 mmol). The reaction mixture was stirred at ꢁ78 ꢂC allowing for
d
formation of ca. 0.3 M solution of corresponding alkynyllithium in
131.8,129.9,128.5,128.0,127.6,126.6,122.2, 88.8, 86.2, 69.4, 61.8, 20.9.
THF. After 1.5 h, 270 ml (15 mmol) of neat D2O (99.99% D) was added
dropwise. Reaction mixture was allowed to warm to room tem-
perature. After warming up, reaction mixture was stirred at room
temperature for 20 min. Reaction mixture was filtered through
a layer of flash Silica (EtOAcdeluent). Solvents were removed un-
der reduced pressure and the residue was purified by column
chromatography (EtOAc/Hex) to give 93.1 mg (32% yield) of the
corresponding deuterated propargyl phosphate 1a-d possessing
99þ% D-incorporation according to the integration of the residual
proton signals in 1H NMR.
4.2.3.15. 4-Methyl-4-phenylpent-1-yn-3-yl acetate (1q). Yield 78%
(procedure A). 1H NMR (500 MHz, CDCl3)
d 7.40–7.45 (m, 2H), 7.34
(t, J¼7.7 Hz, 2H), 7.25 (tt, J¼7.2, 1.3 Hz, 1H), 5.58 (d, J¼2.2 Hz, 1H),
2.39 (d, J¼2.0 Hz, 1H), 1.99 (s, 3H), 1.49 (d, J¼2.9 Hz, 6H); 13C NMR
(126 MHz, CDCl3)
d 169.7, 144.5, 128.0, 126.5, 126.4, 79.6, 74.4, 71.0,
41.7, 24.8, 23.7, 20.7.
4.2.3.16. 4-(4-Methoxyphenyl)-1,1,1-triphenylbut-3-yn-2-yl acetate
(1r). Yield 57% (procedure C). 1H NMR (500 MHz, CDCl3)
7.40 (d,
d
Compound 1a-d: 1H NMR (500 MHz, CDCl3)
d 7.21–7.35 (m, 5H),
J¼7.7 Hz, 6H), 7.33 (t, J¼7.5 Hz, 6H), 7.27 (t, J¼6.9 Hz, 3H), 7.09 (d,
5.11–5.19 (m, 1H), 3.98–4.14 (m, 2H), 3.82–3.98 (m, 2H), 3.09–3.19
J¼9.0 Hz, 2H), 7.02 (s, 1H), 6.76 (d, J¼8.8 Hz, 2H), 3.76 (s, 3H), 1.90 (s,
(m, 2H), 2.58 (d, J¼2.20 Hz, <0.01H), 1.29 (td, J¼7.06, 0.92 Hz, 3H),
3H); 13C NMR (126 MHz, CDCl3)
d
169.7, 159.7, 144.0, 133.2, 129.8,
1.23 (td, J¼7.06, 1.10 Hz, 3H); 13C NMR (126 MHz, CDCl3)
d 135.4,
127.5, 126.5, 114.2, 113.6, 88.8, 84.8, 69.5, 61.8, 55.1, 20.8.
129.8, 128.4, 127.1, 80.3, 75.2 (t, JCD¼38.1 Hz), 68.1 (d, JCP¼5.5 Hz),
63.9 (d, JCP¼5.5 Hz), 63.8 (d, JCP¼5.5 Hz), 42.8 (d, JCP¼6.5 Hz), 16.0
4.2.3.17. 1,1,1-Triphenyl-4-(4-(trifluoromethyl)phenyl)but-3-yn-2-yl
(d, JCP¼6.5 Hz); 2H NMR (76.8 MHz, CDCl3)
d 2.58.
acetate (1s). Yield 85%, (procedure C). 1H NMR (500 MHz, CDCl3)
d
7.47 (d, J¼8.1 Hz, 2H), 7.23–7.37 (m, 15H), 7.20 (d, J¼7.9 Hz, 2H),
4.2.3.24. Diethyl 1-isopropylprop-2-yn-1-yl phosphate-d1 (1h-d).
Compound 1h-d was prepared according to the general procedure
A from the known 2-methylpropanal-d1 in 56% yield. Integration of
the residual proton signals in 1H NMR indicated 93þ% D-
incorporation.
6.97 (s, 1H), 1.91 (s, 3H); 13C NMR (126 MHz, CDCl3)
d
169.8, 143.9,
132.0, 130.3 (q, JCF¼32.4 Hz), 129.8, 127.8, 126.7, 126.0, 125.0 (q,
JCF¼3.7 Hz), 123.8 (q, JCF¼272.0 Hz), 88.8, 87.4, 69.3, 61.8, 20.9.
4.2.3.18. 4-(Furan-2-yl)-1,1,1-triphenylbut-3-yn-2-yl acetate (1t).
Compound 1h-d: 1H NMR (500 MHz, CDCl3)
d
4.80 (dd, J¼7.61,
Yield 64% (procedure C). 1H NMR (500 MHz, CDCl3)
d
7.22–7.37
(m, 16H), 7.00 (s, 1H), 6.34 (d, J¼3.3 Hz, 1H), 6.29 (dd, J¼3.2,
2.1 Hz, 1H), 1.88 (s, 3H); 13C NMR (126 MHz, CDCl3)
169.7, 143.7,
2.11 Hz, 1H), 4.08–4.20 (m, 4H), 2.54 (d, J¼2.20 Hz, 1H), 2.01–2.09
(m, 0.07H), 1.31–1.38 (m, J¼7.11, 7.11, 3.03, 0.92 Hz, 5H), 1.04 (s, 3H),
d
1.00 (s, 3H); 13C NMR (126 MHz, CDCl3)
d 79.7, 75.2, 72.6 (d,
143.6, 136.1, 129.8, 127.9, 127.7, 126.6, 116.3, 110.7, 90.4, 79.2, 69.2,
61.6, 20.8.
JCP¼5.5 Hz), 63.9 (d, JCP¼6.5 Hz), 63.8 (d, JCP¼6.5 Hz), 32.9–33.6 (m),
17.7, 16.9, 16.0 (d, JCP¼2.8 Hz), 16.1 (d, JCP¼3.7 Hz); 2H NMR
(76.8 MHz, CDCl3)
d 2.05 (m).
4.2.3.19. 1-(1,1-Diphenylethyl)prop-2-yn-1-yl acetate (1u). Yield
95% (procedure A). 1H NMR (500 MHz, CDCl3)
d
7.26–7.31 (m, 8H),
4.2.3.25. 1-(Diphenylmethyl)prop-2-yn-1-yl diethyl phosphate-d1
7.20–7.25 (m, 2H), 6.12 (d, J¼2.20 Hz, 1H), 2.41 (d, J¼2.20 Hz, 1H),
(1i-d). Known [(2,2-diphenylvinyl)oxy](trimethyl)silane (2.80 g,

A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
1867
10.44 mmol) was dissolved in 50 ml of anhydrous THF. Solution of
3.17 g of anhydrous CsF (20.88 mmol) in D2O (99.99% D) was added
and reaction mixture was vigorously stirred for 30 min. Formed
2,2-diphenylacetaldehyde-d1 was extracted with anhydrous hex-
anes. Combined organic extracts were dried over anhydrous so-
dium sulfate. Solvents were removed under reduced pressure and
the residue was used without purification in the next step.
acetic anhydride (1 mL, 10 mmol) was added and the reaction
mixture was stirred for several hours. The solution was poured into
50 mL 2 M HCl(aq) and extracted three times with 50 mL of ethyl
acetate. The combined organic phases were dried with anhydrous
magnesium sulfate, filtered, and concentrated. Purification by col-
umn chromatography gave 1.47 g (70%) of 1-(triphenylmethyl)-3-
phenylprop-2-yn-1-yl acetate-d1. Integration of the residual proton
signals in 1H NMR indicated >96% D-incorporation.
Following procedure A, 1-(diphenylmethyl)prop-2-yn-1-yl
diethyl phosphate-d1 (1i-d) was synthesized from a crude 2,2-
diphenylacetaldehyde-d1 in 39% overall yield. Integration of the
residual proton signals in 1H NMR indicated 77% D-incorporation.
Compound 1p-d1: 1H NMR (500 MHz, CDCl3)
d 7.33–7.37 (m,
6H), 7.30 (t, J¼7.4 Hz, 6H), 7.23–7.28 (m, 4H), 7.18–7.23 (m, 2H),
7.10–7.13 (m, 2H), 6.94 (m, 0.04H), 1.89 (s, 3H); 13C NMR (126 MHz,
Compound 1i-d: 1H NMR (500 MHz, CDCl3)
d
7.38–7.42 (m, 2H),
CDCl3) d 169.8, 144.0, 131.8, 129.9, 128.5, 128.0, 127.6, 126.6, 122.2,
7.36 (dd, J¼8.16, 1.01 Hz, 2H), 7.27–7.33 (m, 4H), 7.19–7.25 (m, 2H),
5.65–5.72 (m, 1H), 4.39 (d, J¼9.17 Hz, 1H), 3.96–4.12 (m, 2H), 3.59–
3.69 (m, 1H), 3.45–3.55 (m, 1H), 2.51 (d, J¼2.20 Hz, 1H), 1.28 (td,
J¼7.11, 1.01 Hz, 3H), 1.05 (td, J¼7.06, 1.10 Hz, 3H); 13C NMR
88.8, 86.2, 69.3 (br m), 61.8, 20.9; 2H NMR (76.8 MHz, CDCl3)
d 6.94.
4.3. Optimization of reaction conditions: test and
mechanistic experiments
(126 MHz, CDCl3)
d 139.0–140.5, 128.7, 128.5, 128.5, 127.1, 127.0,
80.3, 76.6, 69.5–69.9 (m), 64.0 (d, JCP¼6.5 Hz), 63.6 (d, JCP¼5.5 Hz),
To a foiled 3–5 ml Wheaton V-vial charged with catalyst and
2 ml of anhydrous dichloromethane or 1,2-dichloroethane was
added propargyl acetate or phosphate (0.1 mmol) under N2 or ar-
gon atmosphere and the reaction mixture was stirred at room
temperature until judged complete by TLC and GC–MS analysis. The
reaction mixture was filtered through a layer of flash Silica
(EtOAcdeluent), the solvents were removed in vacuo, and the
residue was analyzed by 1H NMR using dibromomethane as an
internal standard.
57.0 (d, JCP¼7.4 Hz), 56.3–56.8 (m), 16.0 (d, JCP¼6.5 Hz), 15.9 (d,
JCP¼7.4 Hz); 2H NMR (76.8 MHz, CDCl3)
d 4.39.
4.2.3.26. 1-(Triphenylmethyl)-3-phenylprop-2-yn-1-yl acetate-d1 (1p-
d1). Triphenylacetic acid (4.3 g, 15 mmol), bromoethane (1.3 mL,
18 mmol), and a solution of tetrabutylammonium fluoride in
THF (1.0 M, 18 mL, 18 mmol) were added successively to a 50 mL
flask. The reaction mixture was stirred for 15 h and TLC analysis
judged the reaction complete. The reaction mixture was poured
into 50 mL 2 M HCl(aq) and extracted three times with 25 mL of
ethyl ether. The organic phases were combined, dried over anhy-
drous magnesium sulfate, filtered, and concentrated to give 4.74 g
(99%) of ethyl triphenylacetate, which required no additional
purification.
Ethyl triphenylacetate (2.665 g, 8.4 mmol) was dissolved in an-
hydrous THF (25 mL) and the solution was cooled to 0 ꢂC. LiAlD4
(177 mg, 4.2 mmol) was added as solid portions and the reaction
mixture was kept at 0 ꢂC for an additional hour after complete
addition. The reaction mixture was stirred for another 24 h at room
temperature before being poured into 100 mL of 2 M H2SO4(aq).
The aqueous layer was extracted five times with 25 mL ethyl ether,
the organic extracts were combined, dried over anhydrous mag-
nesium sulfate, filtered, and concentrated to give 1.96 g (84%) of
2,2,2-triphenylethanol-d2.
4.4. General procedure for the synthesis of 1,3-dienes and
naphthalenes
A foiled 25 ml flask with septa was charged with a catalytic
amount of 1:1 mixture of Au(PPh3)Cl and AgOTf specified below
and 10 ml of anhydrous dichloromethane or 1,2-dichloroethane.
After stirring of the reaction mixture for 15 min, propargyl acetate
or phosphate (0.5 mmol) was added under argon atmosphere and
stirring was continued at room temperature until the reaction was
judged complete. The reaction mixture was then filtered through
a layer of flash Silica (EtOAcdeluent), the solvents were removed in
vacuo, and the residue was purified by column chromatography
(EtOAc/Hex: for 1,3-dienes, PhH/Hex: for naphthalenes).
4.4.1. Diethyl (1E,3E)-4-phenylbuta-1,3-dienyl phosphate (2a)
Yield 83%, 2.5 mol % Au, 0.5 mmol scale, 1 h. 1H NMR (500 MHz,
CDCl3) d 7.36 (s, 2H), 7.28–7.33 (m, 2H), 7.19–7.24 (m, 1H), 6.83 (dd,
To a 200 mL flask equipped with a stirbar was added anhydrous
dichloromethane (50 mL) and the flask was cooled to ꢁ78 ꢂC.
Oxalyl chloride (720
m
L, 8.5 mmol) was added via syringe, followed
J¼11.92, 6.42 Hz, 1H), 6.64 (dd, J¼15.77, 11.00 Hz, 1H), 6.52 (d,
by the dropwise addition of dimethylsulfoxide (1 mL, 14.2 mmol).
The solution was allowed to stir at ꢁ78 ꢂC for 30 min before a so-
lution of 2,2,2-triphenylethanol-d2 (1.96 g, 7.1 mmol) dissolved in
anhydrous dichloromethane (20 mL) was added slowly via cannula.
The reaction mixture was stirred for another 30 min before tri-
ethylamine (4 mL, 28.4 mmol) was added. The reaction mixture
was stirred a further 30 min before being brought to room tem-
perature. After several hours, the reaction mixture was poured into
100 mL 2 M HCl(aq) and extracted three times with 25 mL
dichloromethane. The organic phases were combined, dried with
anhydrous magnesium sulfate, filtered, and concentrated. Purifi-
cation by column chromatography gave 1.64 g (85%) of triphenyl-
acetaldehyde-d1.
J¼15.77 Hz, 1H), 6.21 (t, J¼11.46 Hz, 1H), 4.15–4.24 (m, 4H), 1.37 (td,
J¼7.11, 1.01 Hz, 6H); 13C NMR (126 MHz, CDCl3)
d 139.7 (d,
JCP¼5.5 Hz), 137.1, 132.0, 128.6, 127.5, 126.1, 122.9, 118.0 (d,
JCP¼11.1 Hz), 64.6 (d, JCP¼5.5 Hz), 16.1 (d, JCP¼5.5 Hz); HRMS (EI)
calcd for C14H19O4P: 282.10210, found: 282.10225.
4.4.2. Diethyl (1E,3E)-4-phenylpenta-1,3-dien-1-yl phosphate (2b)
Yield 69%, 5 mol % Au, 0.5 mmol scale, 1 h (4.3:1 (1E,3E)/(1E,3Z)).
1H NMR (500 MHz, CDCl3)
d
7.17–7.44 (m, 5H), 6.82 (dd, J¼11.46,
6.14 Hz, 0.2H), 6.71 (dd, J¼11.65, 5.78 Hz, 0.8H), 6.43 (t, J¼11.65 Hz,
0.2H), 6.32 (d, J¼11.55 Hz, 0.2H), 6.09 (t, J¼11.65 Hz, 0.8H), 5.99 (d,
J¼11.55 Hz, 0.8H), 4.03–4.26 (m, 4H), 2.09–2.15 (two ov. s, 3H),
1.29–1.42 (m, 6H); 13C NMR (126 MHz, CDCl3)
d 141.16, 138.91,
Phenylacetylene (660
m
L, 6 mmol) was dissolved in 5 mL anhy-
138.66, 138.61, 128.32, 128.20, 128.08, 127.11, 127.06, 125.50, 120.57,
115.59, 115.51, 64.56, 64.52, 64.43, 64.38, 25.46, 16.09, 16.04; HRMS
(EI) calcd for C15H21O4P: 296.11775, found: 296.1182.
drous THF and the solution was cooled to ꢁ78 ꢂC. A solution of
butyllithium in hexanes (2.5 M, 2.1 mL, 5.5 mmol) was added
dropwise and the reaction mixture was stirred at ꢁ78 ꢂC for 1 h.
Meanwhile, triphenylacetaldehyde-d1 (1.37 g, 5 mmol) was dis-
solved in anhydrous THF (5 mL) and the solution was added via
cannula to the lithium acetylide at ꢁ78 ꢂC. The reaction mixture
was stirred for 30 min before being warmed to 0 ꢂC. After 10 min,
4.4.3. (1E,3E)-4-Phenylbuta-1,3-dien-1-yl acetate (2c)
Yield 79%, 2.5 mol % Au, 0.5 mmol scale, 2 h. 1H NMR (500 MHz,
CDCl3)
d
7.53 (d, J¼12.29 Hz, 1H), 7.29–7.41 (m, 4H), 7.20–7.25 (m,
1H), 6.71 (dd, J¼15.50, 11.28 Hz, 1H), 6.55 (d, J¼15.59 Hz, 1H), 6.21

1868
A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
(m, 1H), 2.18 (s, 3H); 13C NMR (126 MHz, CDCl3)
137.15, 132.30, 128.63, 127.50, 126.15, 123.64, 115.88, 20.68; HRMS
(EI) calcd for C12H12O2: 188.0837, found: 188.0836.
d
167.70, 138.73,
124.30, 123.42, 33.04, 31.82, 31.07, 30.45, 29.66, 25.63, 23.43, 23.04,
22.71, 14.16.
4.4.11. 1,2-Diphenylnaphthalene (3m)
4.4.4. (1E,3E)-4-Phenylbuta-1,3-dien-1-yl pivalate (2d)
Yield 86%, 5 mol % Ph3PAuOTf, 0.5 mmol scale, 1 h. 1H NMR
Yield 86%, 2.5 mol % Au, 0.5 mmol scale, 4 h. 1H NMR (500 MHz,
(500 MHz, CDCl3)
d
7.94 (dd, J¼8.25, 4.95 Hz, 2H), 7.69 (d,
CDCl3)
d
7.53 (d, J¼12.29 Hz, 1H), 7.29–7.42 (m, 4H), 7.20–7.25 (m,
J¼8.44 Hz, 1H), 7.60 (d, J¼8.62 Hz, 1H), 7.48–7.53 (m, 1H), 7.42 (dt,
1H), 6.73 (dd, J¼15.68, 11.10 Hz, 1H), 6.54 (d, J¼15.77 Hz, 1H), 6.24
J¼8.44, 6.97, 1.28 Hz, 1H), 7.27–7.35 (m, 3H), 7.14–7.24 (m, 7H); 13C
(t, J¼11.65 Hz, 1H), 1.28 (s, 9H); 13C NMR (126 MHz, CDCl3)
NMR (126 MHz, CDCl3)
d 142.01, 139.02, 138.35, 137.64, 132.79,
d
175.26, 139.23, 137.24, 131.95, 128.62, 127.43, 126.14, 123.83,
132.68, 131.46, 130.14, 128.30, 127.89, 127.81, 127.60, 126.84, 126.73,
126.23, 126.20, 125.69.
115.68, 38.77, 26.94; HRMS (EI) calcd for C15H18O2: 230.1307,
found: 230.1308.
4.4.12. 4-Butyl-1,2-diphenylnaphthalene (3n)
4.4.5. Diethyl (1E,3E)-4-Methylhexa-1,3-dien-1-yl phosphate (2e)
Yield 75%, 5 mol % Au, 0.5 mmol scale, 4 h (1.3:1 (1E,3E)/(1E,3Z)).
Yield 94%, 10 mol % Ph3PAuOTf, 2 h. 1H NMR (500 MHz, CDCl3)
d
8.15 (d, J¼8.4 Hz, 1H), 7.72 (d, J¼8.4 Hz, 1H), 7.54 (ddd, J¼8.3, 6.9,
1H NMR (500 MHz, CDCl3)
d
6.55–6.64 (m, 1H), 6.18–6.28 (m, 1H),
1.3 Hz, 1H), 7.47 (s, 1H), 7.41 (ddd, J¼8.4, 6.9, 1.2 Hz, 1H), 7.27–7.34
(m, 3H), 7.13–7.24 (m, 7H), 3.15–3.21 (m, 2H), 1.82–1.90 (m, 2H),
1.51–1.61 (m, 2H), 1.03 (t, J¼7.4 Hz, 3H); 13C NMR (126 MHz, CDCl3)
5.60–5.70 (m,1H), 4.11–4.21 (m, 4H), 2.10 (q, J¼7.64 Hz,1H), 2.05 (q,
J¼7.40 Hz, 1H), 1.75 (s, 1.5H), 1.69 (s, 1.5H), 1.34 (tt, J¼7.06, 1.19 Hz,
6H), 1.00 (t, J¼7.52 Hz, 1.5H), 0.98 (t, J¼7.61 Hz, 1.5H); 13C NMR
d
142.3, 139.3, 138.4, 137.9, 135.9, 133.1, 131.7, 131.2, 130.1, 128.3,
(126 MHz, CDCl3)
d
141.14, 140.83, 137.48, 137.44, 117.63, 116.59,
127.8, 127.6, 127.6, 126.6, 126.1, 125.7, 125.4, 123.8, 33.0, 33.0, 23.1,
14.1; HRMS (EI) calcd for C26H24: 336.1878, found: 336.1880.
114.79, 114.71, 114.37, 114.29, 64.37, 64.32, 32.48, 25.30, 23.19, 16.51,
16.09, 16.04, 12.75, 12.39.
4.4.13. 1,2,4-Triphenylnaphthalene (3p)
4.4.6. (E)-2-(2-Phenylcyclohex-1-enyl)vinyl acetate (2f)
Yield 75%, 10 mol % Ph3PAuOTf, 12 h. 1H NMR (500 MHz, CDCl3)
Yield 70%, 2.5 mol % Au, 0.5 mmol scale, 5 h. 1H NMR (500 MHz,
d
7.99–8.06 (m, 1H), 7.76–7.80 (m, 1H), 7.60–7.65 (m, 2H), 7.59 (s,
1H), 7.51–7.56 (m, 2H), 7.41–7.50 (m, 3H), 7.27–7.38 (m, 5H), 7.14–
7.25 (m, 5H); 13C NMR (126 MHz, CDCl3)
141.86, 140.64, 139.81,
CDCl3)
7.13–7.16 (m, 2H), 6.12 (d, J¼12.7 Hz, 1H), 2.25–2.41 (m, 4H), 2.07 (s,
3H), 1.72–1.81 (m, 4H); 13C NMR (126 MHz, CDCl3)
168.2, 143.1,
d
7.33–7.37 (m, 2H), 7.32 (d, J¼6.6 Hz, 1H), 7.24–7.28 (m, 1H),
d
d
139.09, 137.92, 137.17, 133.10, 131.58, 130.98, 130.21, 130.16, 129.39,
128.34, 127.88, 127.62, 127.37, 127.21, 126.79, 126.26, 126.06, 125.76.
138.9, 134.4, 128.6, 128.1, 126.8, 126.5, 116.0, 32.9, 25.5, 23.0, 22.4,
20.7; HRMS (EI) calcd for C16H18O2: 242.1307, found: 242.1303.
4.4.14. 1,2-Dimethylnaphthalene (3q)
4.4.7. (1E)-3-Cyclohexylideneprop-1-en-1-yl diethyl
phosphate (2g)
Yield 73%, 10 mol % Ph3PAuOTf, 1 h. 1H NMR (500 MHz, CDCl3)
d
8.05 (d, J¼8.44 Hz, 1H), 7.81 (d, J¼8.07 Hz, 1H), 7.63 (d, J¼8.25 Hz,
1H), 7.46–7.53 (m, 1H), 7.42 (t, J¼7.24 Hz, 1H), 7.31 (d, J¼8.25 Hz,
1H), 2.62 (s, 3H), 2.50 (s, 3H); 13C NMR (126 MHz, CDCl3)
133.12,
Yield 82%, 7.5 mol % Au, 0.5 mmol scale, 4 h. 1H NMR (500 MHz,
CDCl3)
d
6.59 (dd, J¼11.74, 5.87 Hz, 1H), 6.25 (t, J¼11.65 Hz, 1H), 5.59
d
(d, J¼11.55 Hz, 1H), 4.09–4.19 (m, 4H), 2.04–2.23 (m, 4H), 1.45–1.56
132.82, 132.24, 131.12, 129.00, 128.40, 125.70, 125.67, 124.45, 123.70,
20.78, 14.51.
(m, 6H), 1.33 (t, J¼7.15 Hz, 6H); 13C NMR (126 MHz, CDCl3)
d 143.56,
137.62, 137.58, 114.98, 114.02, 113.94, 64.36, 64.31, 37.23, 29.18,
28.40, 27.61, 26.66, 16.09, 16.04.
4.4.15. 4-(4-Methoxyphenyl)-1,2-diphenylnaphthalene (3r)
Yield 90%, 10 mol % Ph3PAuOTf, 2 h. 1H NMR (500 MHz, CDCl3)
4.4.8. (E)-2-(2-Phenylcyclopent-1-enyl)vinyl acetate (2j)
d
8.08 (d, J¼7.9 Hz, 1H), 7.80 (dd, J¼8.2, 1.2 Hz, 1H), 7.60 (s, 1H), 7.57
Yield 54%, 10 mol % Au, 0.2 mmol scale, 12 h. 1H NMR (500 MHz,
(d, J¼8.6 Hz, 2H), 7.43–7.50 (m, 2H), 7.28–7.39 (m, 5H), 7.17–7.27 (m,
CDCl3)
d
7.42 (dt, J¼12.5, 1.1 Hz, 1H), 7.36–7.40 (m, 2H), 7.29–7.33
5H), 7.10 (d, J¼8.6 Hz, 2H), 3.94 (s, 3H); 13C NMR (126 MHz, CDCl3)
(m, 2H), 7.26–7.28 (m, 1H), 6.51 (d, J¼12.5 Hz, 1H), 2.84 (t, J¼7.4 Hz,
d 159.0, 141.9, 139.4, 139.1, 137.9, 136.8, 133.1, 132.9, 131.5, 131.2,
2H), 2.67 (t, J¼7.4 Hz, 2H), 2.16 (s, 3H), 1.98–2.06 (m, 2H); 13C NMR
131.1, 130.1, 129.3, 127.8, 127.6, 127.1, 126.7, 126.2, 126.0, 126.0, 125.6,
113.8, 55.3; HRMS (EI) calcd for C29H22O: 386.1671, found:
386.1670.
(126 MHz, CDCl3)
d 168.0, 141.4, 137.9, 137.7, 131.8, 128.2, 127.9,
126.9, 111.5, 37.8, 33.9, 21.9, 20.7.
4.4.9. 1,2,3,4-Tetrahydrophenanthrene (3k)
4.4.16. 1,2-Diphenyl-4-(4-(trifluoromethyl)phenyl)-
naphthalene (3s)
Yield 36%, 10 mol % Ph3PAuOTf, 0.5 mmol scale, 16 h; 96%,
10 mol % (F5C6)3PAuSbF6, 0.5 mmol scale, 2.5 h. 1H NMR (500 MHz,
Yield 84%, 10 mol % Ph3PAuOTf, 2 h. 1H NMR (400 MHz, CDCl3)
CDCl3)
d
7.98 (d, J¼8.44 Hz, 1H), 7.81 (d, J¼8.07 Hz, 1H), 7.63 (d,
d
7.89–7.93 (m, 1H), 7.69–7.82 (m, 5H), 7.55 (s, 1H), 7.42–7.50 (m,
2H), 7.30–7.38 (m, 3H), 7.23–7.27 (m, 2H), 7.13–7.22 (m, 5H); 13C
NMR (101 MHz, CDCl3) 144.3, 141.5, 138.7, 138.2, 137.9, 133.1, 131.4,
J¼8.44 Hz, 1H), 7.51 (ddd, J¼8.39, 6.83, 1.47 Hz, 1H), 7.41–7.47 (m,
1H), 7.22 (d, J¼8.44 Hz, 1H), 3.14 (t, J¼6.33 Hz, 2H), 2.93 (t,
J¼6.14 Hz, 2H), 1.95–2.04 (m, 2H), 1.85–1.94 (m, 2H); 13C NMR
d
130.6, 130.5, 130.1, 129.7, 129.4, 127.9, 127.7, 127.4, 126.9, 126.4,
126.3, 126.1, 125.5, 125.3 (q, JCF¼3.7 Hz), 125.1 (q, JCF¼272.0 Hz);
HRMS (EI) calcd for C29H19F3: 424.1439, found: 424.1440.
(126 MHz, CDCl3)
d 134.35, 132.56, 132.07, 131.52, 128.39, 128.30,
125.78, 125.62, 124.69, 122.80, 30.49, 25.71, 23.28, 22.99.
4.4.10. 9-Hexyl-1,2,3,4-tetrahydrophenanthrene (3l)
4.4.17. 2-(3,4-Diphenylnaphthalen-1-yl)furan (3t)
Yield 30%, 10 mol % Ph3PAuOTf, 0.5 mmol scale, 20 h; 75%,
Yield 94%, 10 mol % Ph3PAuOTf, 2 h. 1H NMR (500 MHz, CDCl3)
10 mol % (F5C6)3PAuSbF6, 0.5 mmol scale, 2.5 h. 1H NMR (500 MHz,
d
8.57 (d, J¼8.4 Hz, 1H), 7.94 (s, 1H), 7.82 (d, J¼8.6 Hz, 1H), 7.73 (dd,
CDCl3)
d
7.98–8.06 (m, 2H), 7.45–7.53 (m, 2H), 7.07 (s, 1H), 3.11 (t,
J¼1.7, 0.7 Hz, 1H), 7.63 (ddd, J¼8.5, 6.9, 1.3 Hz, 1H), 7.52 (ddd, J¼8.4,
6.9, 1.2 Hz, 1H), 7.34–7.43 (m, 4H), 7.27–7.33 (m, 4H), 7.21–7.27 (m,
2H), 6.87 (dd, J¼3.3, 0.6 Hz, 1H), 6.69 (dd, J¼3.3, 1.8 Hz, 1H); 13C
J¼6.33 Hz, 2H), 2.98–3.06 (m, 2H), 2.90 (t, J¼6.14 Hz, 2H), 1.94–2.02
(m, 2H), 1.85–1.92 (m, 2H), 1.71–1.80 (m, 2H), 1.44–1.52 (m, 2H),
1.32–1.41 (m, 4H), 0.90–0.97 (m, 3H); 13C NMR (126 MHz, CDCl3)
NMR (126 MHz, CDCl3)
d 153.3, 142.5, 141.6, 138.9, 138.0, 138.0,
d
136.34, 133.93, 132.99, 130.59, 129.61, 128.23, 125.30, 124.46,
133.3, 131.4, 130.0, 129.8, 128.6, 128.2, 127.8, 127.6 127.4, 126.8,

A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
1869
126.3, 126.2, 126.2, 125.5, 111.4, 109.5; HRMS (EI) calcd for C26H18O:
346.1358, found: 346.1357.
4.4.25. 1,2,4-Triphenylnaphthalene-dn (3p-dn)
Yield 78%, 10 mol % Ph3PAuOTf, 0.2 mmol, 3 h. 1H NMR
(500 MHz, CDCl3)
7.66 (m, 2H), 7.61 (s, 0.67H), 7.55 (t, J¼7.4 Hz, 2H), 7.42–7.51 (m, 3H),
7.28–7.40 (m, 5H), 7.13–7.26 (m, 5H). Note: no loss of D-label in 3p-
dn in the presence of 10 mol % of Ph3PAuOTf catalyst and 1 equiv of
AcOH was observed within 12 h.
d
8.05 (d, J¼8.3 Hz, 1H), 7.78–7.82 (m, 1H), 7.62–
4.4.18. 1-Methyl-2-phenylnaphthalene (3u)
Yield 51%, 10 mol % Ph3PAuOTf, 7 h. 1H NMR (500 MHz, CDCl3)
d
8.11–8.14 (m, 1H), 7.90 (dt, J¼8.07, 0.73 Hz, 1H), 7.77 (d, J¼8.44 Hz,
1H), 7.57–7.61 (m, 1H), 7.51–7.55 (m, 1H), 7.45–7.50 (m, 2H), 7.38–
7.44 (m, 4H), 2.63 (s, 3H); 13C NMR (126 MHz, CDCl3)
142.73,
d
139.06, 132.95, 132.73, 130.81, 129.81, 128.47, 128.31, 128.08, 126.76,
126.20, 125.84, 125.47, 124.57, 16.29.
4.4.26. Diethyl 4-phenylbuta-1,2-dien-1-yl phosphate (4a)
To a foiled 10 ml flask with septa charged with 10 mol % of
AgOTf and 6 ml of anhydrous 1,2-dichloroethane was added
propargyl phosphate 1a (0.3 mmol) under argon atmosphere and
the reaction mixture was stirred at room temperature overnight.
The reaction mixture was then filtered through a layer of flash
Silica (EtOAcdeluent), the solvents were removed in vacuo, and
the residue was purified by column chromatography (EtOAc/
hexanes) to give 73% of allene 4a (5:1 mixture together with
unreacted 1a).
4.4.19. 1,2-Dimethyl-4-phenylnaphthalene (3v)
Yield 57%, 10 mol % (F5C6)3PAuSbF6, 0.5 mmol scale, 2.5 h. 1H NMR
(500 MHz, CDCl3)
7.55 (m, 7H), 7.29 (s, 1H), 2.67 (s, 3H), 2.54 (s, 3H); 13C NMR (126 MHz,
CDCl3) 141.04, 137.93, 133.10, 132.64, 130.73, 130.38, 130.17, 130.12,
d
8.12 (d, J¼8.62 Hz,1H), 7.88 (d, J¼8.44 Hz,1H), 7.35–
d
128.16, 127.00, 126.50, 125.64, 124.57, 123.96, 20.75, 14.63.
4.4.20. 4-Butyl-1,2-dimethylnaphthalene (3w)
Compound 4a: 1H NMR (400 MHz, CD3CN)
d
7.32 (t, J¼7.3 Hz,
Yield 77%, 10 mol % (F5C6)3PAuSbF6, 0.5 mmol scale, 2.5 h. 1H
2H), 7.20–7.28 (m, 3H), 6.70–6.76 (m, J¼7.8, 5.7, 1.9, 1.9 Hz, 1H),
6.04–6.12 (m, J¼7.1, 7.1, 5.6, 2.9 Hz, 1H), 4.02–4.13 (m, 4H), 3.46 (dd,
J¼7.0, 1.8 Hz, 2H), 1.28 (t, J¼7.0 Hz, 6H); 13C NMR (101 MHz, CD3CN)
NMR (500 MHz, CDCl3)
d
8.05 (ddd, J¼15.68, 8.25, 1.19 Hz, 2H),
7.43–7.53 (m, J¼21.85, 8.28, 6.74, 1.47 Hz, 2H), 7.17 (s, 1H), 3.00–3.07
(m, 2H), 2.59 (s, 3H), 2.48 (s, 3H), 1.70–1.78 (m, 2H), 1.43–1.53 (m,
d
196.7 (d, JCP¼10.2 Hz), 139.9, 129.7, 129.5, 127.5, 113.5 (d,
2H), 0.99 (t, J¼7.34 Hz, 3H); 13C NMR (126 MHz, CDCl3)
d
136.33,
JCP¼5.9 Hz), 107.0, 65.3 (d, JCP¼5.9 Hz), 37.3, 16.5 (d, JCP¼6.6 Hz).
Compound 4a underwent quantitative transformation into 2a in
the presence of 5 mol % of 1:1 mixture of Ph3PAuCl/AgOTf catalyst
under standard conditions (0.1 mmol scale).
133.26,132.65,130.62,129.23,129.12,125.22,124.39,124.30,124.20,
33.28, 32.73, 22.98, 20.76, 14.46, 14.04.
4.4.21. 8,9,10,11-Tetrahydro-7H-cyclohepta[a]naphthalene (3x)
Yield 74%, 10 mol % (F5C6)3PAuSbF6, 0.5 mmol scale, 2.5 h. 1H
4.5. Monitoring Au-catalyzed transformation of 1a into 2a
NMR (500 MHz, CDCl3)
d
8.12–8.16 (m, 1H), 7.83 (dt, J¼8.07, 0.73 Hz,
1H), 7.63 (d, J¼8.25 Hz, 1H), 7.46–7.52 (m, 1H), 7.39–7.43 (m, 1H),
An NMR tube, fitted with a rubber septa, was evacuated and
7.30 (d, J¼8.25 Hz, 1H), 3.25–3.31 (m, 2H), 2.99–3.04 (m, 2H), 1.90–
backfilled with argon. A solution of 14 mg 1a dissolved in 600
anhydrous CDCl3 was injected into the tube and a 1H spectrum was
recorded. The sample was removed and 50 L of a solution of
2.4 mg Ph3PAuCl and 1.2 mg AgOTf in 100 L anhydrous CDCl3 was
mL
1.96 (m, 2H),1.67–1.75 (m, 4H); 13C NMR (126 MHz, CDCl3)
d 140.92,
138.55, 132.60, 131.67, 128.62, 128.37, 125.85, 125.67, 124.33, 123.34,
36.64, 32.45, 28.06, 27.65, 26.88.
m
m
injected. The tube was quickly shaken and after 1 min the 1H
spectrum was recorded. Spectra were obtained at t¼0, 1, 2, 4, 6, 8,
10, 12, 14, 16, 18, 20, and 40 min (at which time no starting material
or allene was present). Analysis of the spectra concluded that the
allene and diene were the sole components observable under the
reaction conditions and no other diene isomers formed in detect-
able quantities.
4.4.22. Diethyl (1E,3E)-4-phenylbuta-1,3-dien-1-yl phosphate-d1
(2a-d)
Yield 77%, 5 mol % Ph3PAuOTf, 0.1 mmol scale, 1.5 h. 1H NMR
(500 MHz, CDCl3)
d 7.34–7.39 (m, 2H), 7.28–7.34 (m, 2H), 7.19–7.24
(m, 1H), 6.83 (m, <0.02H), 6.60–6.70 (m, 1H), 6.47–6.55 (m, 1H),
6.20 (d, J¼10.82 Hz, 1H), 4.16–4.23 (m, 4H), 1.37 (td, J¼7.11, 1.01 Hz,
8H); 13C NMR (126 MHz, CDCl3)
d 139.1–139.7 (m), 137.1, 132.0,
Allene intermediate 4a was also observed during GC–MS mon-
itoring of 1a isomerization reaction course.
128.6, 127.5, 126.1, 122.9, 117.9 (d, JCP¼10.2 Hz), 64.5 (d, JCP¼5.5 Hz),
16.1 (d, JCP¼6.5 Hz); 2H NMR (76.8 MHz, CDCl3)
d 6.85.
4.4.23. Diethyl (1E)-4-methylpenta-1,3-dien-1-yl phosphate-dn
(2h-dn)
4.6. Monitoring Au-catalyzed transformation of 1m into 3m
Yield 65%, 7 mol % Ph3PAuOTf, 0.5 mmol scale, 20 h. 1H NMR
4.6.1. Diethyl 4,4,4-triphenylbuta-1,2-dien-1-yl phosphate (4m)
To a foiled 10 ml flask with septa charged with 10 mol % of AgOTf
and 6 ml of anhydrous 1,2-dichloroethane was added propargyl
phosphate 1m (0.3 mmol) under argon atmosphere and the re-
action mixture was stirred at room temperature overnight. The
reaction mixture was then filtered through a layer of flash Silica
(EtOAcdeluent), the solvents were removed in vacuo, and the
residue was purified by column chromatography (EtOAc/Hexanes)
to give 99þ% of allene 4m (2:1 mixture together with unreacted
1m).
(500 MHz, CDCl3)
d
6.59 (dd, J¼11.65, 5.78 Hz, 0.73H), 6.22 (t,
J¼11.55 Hz, 0.79H), 5.63–5.71 (m, 0.98H), 4.10–4.22 (m, 4H), 1.77 (s,
3H), 1.70 (s, 3H), 1.35 (td, J¼7.06, 0.92 Hz, 6H); 13C NMR (126 MHz,
CDCl3)
d
137.3 (d, JCP¼5.5 Hz), 135.4, 118.2, 114.7 (d, JCP¼11.1 Hz),
64.4 (d, JCP¼5.5 Hz), 26.0, 18.2, 16.1 (d, JCP¼6.5 Hz); 2H NMR
(76.8 MHz, CDCl3)
d 6.61, 6.25, 5.68.
4.4.24. (1E)-4,4-Diphenylbuta-1,3-dien-1-yl diethyl phosphate
(2i-dn)
Yield 64%, 5 mol % Ph3PAuOTf, 0.5 mmol scale, 8 h. 1H NMR
Compound 4m: 1H NMR (500 MHz, CDCl3)
d 7.19–7.39 (m), 7.05–
(500 MHz, CDCl3)
d
7.37–7.42 (m, 2H), 7.32–7.37 (m, 1H), 7.17–7.31
7.15 (m), 6.89 (dd, J¼5.50, 2.38 Hz), 6.73–6.77 (m), 6.39 (dd, J¼6.51,
(m, 7H), 6.90 (dd, J¼11.92, 6.05 Hz, 0.9H), 6.54–6.62 (m, 1H), 6.13
2.11 Hz), 3.91–4.16 (m), 3.46–3.69 (m), 2.53 (d, J¼2.02 Hz),1.18–1.32
(td, J¼11.74, 1.10 Hz, 0.67H), 4.11–4.20 (m, 4H), 1.34 (td, J¼7.11,
(m), 1.04 (td, J¼7.06, 1.10 Hz); 13C NMR (126 MHz, CDCl3)
d 195.6 (d,
1.01 Hz, 6H); 13C NMR (126 MHz, CDCl3)
d
142.7, 142.0, 140.6 (d,
JCP¼11.1 Hz), 145.1, 130.1, 129.9, 127.8, 127.6, 126.7, 115.5 (d,
JCP¼5.5 Hz), 114.9, 80.3, 79.0, 72.4 (d, JCP¼6.5 Hz), 64.2 (t, J¼6.9 Hz),
64.0 (d, JCP¼6.5 Hz), 63.6 (d, JCP¼5.5 Hz), 62.0 (d, JCP¼8.3 Hz), 16.0
(d, JCP¼6.5 Hz), 15.9 (d, JCP¼6.5 Hz).
JCP¼5.5 Hz), 139.4, 130.3, 128.3 (d, JCP¼5.5 Hz), 127.4 (d, JCP¼3.7 Hz),
127.4, 121.4–121.9 (ov. s), 116.1 (d, JCP¼11.1 Hz), 64.5 (d, JCP¼5.5 Hz),
16.1 (d, JCP¼6.5 Hz); 2H NMR (76.8 MHz, CDCl3)
d 6.94, 6.17.

1870
A.S. Dudnik et al. / Tetrahedron 65 (2009) 1859–1870
16. For review on 1,2-alkyl migrations in cascade reactions catalyzed by
see: Crone, B.; Kirsch, S. F. Chem.dEur. J. 2008, 14, 3514.
p-acids,
Allene 4m was observed as a sole intermediate during GC–MS
monitoring of 1m cycloisomerization reaction course.
17. For recent review on naphthalene syntheses, see: de Koning, C. B.; Rousseau, A. L.;
van Otterlo, W. A. L. Tetrahedron 2003, 59, 7.
18. For selected examples, see: (a) Dyker, G.; Hilderbrandt, D.; Liu, J.; Merz, K.
Angew. Chem., Int. Ed. 2003, 42, 4399; (b) Zhao, J.; Hughes, C. O.; Toste, F. D.
J. Am. Chem. Soc. 2006, 128, 7436; (c) Asao, N.; Takahashi, K.; Lee, S.; Kasahara, T.;
Yamamoto, Y. J. Am. Chem. Soc. 2002, 124, 12650; (d) Asao, N.; Sato, K. Org. Lett.
2006, 8, 5361.
Acknowledgements
The support of the National Institutes of Health (Grant GM-
64444) is gratefully acknowledged.
19. Hamura, T.; Morita, M.; Matsumoto, T.; Suzuki, K. Tetrahedron Lett. 2003, 44, 167
and references therein.
20. (a) Saucy, G.; Marbet, R.; Lindlar, H.; Isler, O. Helv. Chim. Acta 1959, 42, 1945; (b)
Schlossarczyk, H.; Sieber, W.; Hesse, M.; Hansen, H.-J.; Schmid, H. Helv. Chim.
Acta 1973, 56, 875; (c) Cookson, R. C.; Cramp, M. C.; Parsons, P. J. J. Chem. Soc.,
Chem. Commun. 1980, 197.
21. Seregin, I. V.; Gevorgyan, V. J. Am. Chem. Soc. 2006, 128, 12050.
22. Correa, A.; Marion, N.; Fensterbank, L.; Malacria, M.; Nolan, S. P.; Cavallo, L.
Angew. Chem., Int. Ed. 2008, 47, 718.
23. There has been a recent discussion on the role of Brønsted acids in homoge-
nous transition metal-catalyzed reactions. For selected examples, see: (a)
Hashmi, A. S. K. Catal. Today 2007, 122, 211; (b) Li, Z.; Zhang, J.; Brouwer, C.;
Yang, C.-G.; Reich, N. W.; He, C. Org. Lett. 2006, 8, 4175; (c) Rosenfeld, D. C.;
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(d) Rhee, J. U.; Krische, M. J. Org. Lett. 2005, 7, 2493.
24. Generally, significant loss of deuterium label is common for trans-
formations involving elimination of the label as deuteron during the re-
action course.
25. Reversible protonation at C-1 of 1,3-dienyl phosphates 2h-dn and 2i-dn under
the prolonged reaction times is the most likely reason for the observed notable
incorporation of D at C-1. A reversible Au-catalyzed 1,2-migration of phos-
phatyloxy group in 1,3-diene product with the formation of C1–Au bond could
also trigger this process.
26. For selected examples on counteranion effect in gold-catalyzed trans-
formations, see: (a) Markham, J. P.; Staben, S. T.; Toste, F. D. J. Am. Chem. Soc.
2005, 127, 9708; (b) Zhang, Z.; Liu, C.; Kinder, R. E.; Han, X.; Qian, H.; Wi-
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29. For selected examples, see: (a) Dudnik, A. S.; Gevorgyan, V. Angew. Chem., Int.
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7. Wang, S.; Zhang, L. Org. Lett. 2006, 8, 4585.
30. Au(I)-catalyzed 6
p-electrocyclization of 1,3-diene 2 followed by elimination
can also account for the observed overall carbocyclization. For example, see:
Menz, H.; Kirsch, S. F. Org. Lett. 2006, 8, 4795.
31. See, for example: (a) Luzung, M. R.; Mauleo´n, P.; Toste, F. D. J. Am. Chem. Soc.
2007, 129, 12402; (b) See also Refs. 4a and b.
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32. For selected examples, see: (a) Gorin, D. J.; Davis, N. R.; Toste, F. D. J. Am. Chem.
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Soc. 2005, 127, 10500.
11. Wang, S.; Zhang, L. J. Am. Chem. Soc. 2006, 128, 14274.
12. Dudnik, A. S.; Sromek, A. W.; Rubina, M.; Kim, J. T.; Kel’in, A. V.; Gevorgyan, V.
J. Am. Chem. Soc. 2008, 130, 1440.
33. Unfortunately, 1,3-dienes such as 2a and 2i did not cyclize into corre-
sponding naphthalenes upon prolonged reaction times even at elevated
temperatures. This observation suggests that formation of the naphthalene
13. Dudnik, A. S.; Schwier, T.; Gevorgyan, V. Org. Lett. 2008, 10, 1465.
14. Dudnik, A. S.; Schwier, T.; Gevorgyan, V. J. Organomet. Chem. 2008. doi:10.1016/
j.jorganchem.2008.08.010
core most likely does not proceed via
pathway.
34. For similar considerations, see: Aggarwal, V. K.; Sheldon, C. G.; Macdonald, G. J.;
a simple 6p-electrocyclization
15. For general review, see: (a) Ducrot, P. H. In One or More CH and/or CC Bond(s)
Formed by Rearrangement; Katritzky, A. R., Taylor, R. J. K., Eds.; Comprehensive
Organic Functional Group Transformations II; Elsevier: Oxford, UK, 2005; vol. 1,
pp 375–426.
Martin, W. P. J. Am. Chem. Soc. 2002, 124, 10300.