Rhodium- and palladium-catalyzed 1,5-substitution reactions of 2-En-4-yne acetates and carbonates with organoboronic acids

Article abstract of DOI:10.1021/jo200201r

Two methods involving the rhodium-catalyzed reaction of 2-en-4-yne acetates and the palladium-catalyzed reaction of 2-en-4-yne carbonates with organoboronic acids were investigated; both afforded exclusively the (E)-configured vinylallenes. The coordinative interaction of the rhodium with the acetate group promoted the δ-elimination of Rh(I)-OAc from the alkenylrhodium intermediate II in both syn and anti modes, with the syn-elimination being the major path. DFT calculations revealed that a conformer of this intermediate (II), which can lead to the (E)-configured vinylallene product via the syn-elimination mode, is energetically the most favorable conformer. The rhodium-catalyzed procedure is not applicable to reactions involving (E)-configured enyne acetates, because the geometry of the alkenylrhodium intermediate that is derived from the corresponding (E)-enyne acetate would not allow such coordinative interaction to occur. The palladium-catalyzed method, which proceeds through formation of the σ-vinylallenylpalladium intermediate, B, is suitable for both the (E)- and (Z)-configured enyne carbonates and appears to have a wider scope for both organoboronic acids and enyne substrates. The palladium-catalyzed reaction of an enantiomerically enriched enyne carbonate proceeded with racemization.

Full text of DOI:10.1021/jo200201r

ARTICLE
pubs.acs.org/joc
Rhodium- and Palladium-Catalyzed 1,5-Substitution Reactions of
2-En-4-yne Acetates and Carbonates with Organoboronic Acids
†
†
†
†
‡
€
€
Muhammed Uc€unc€u, Erman Karakus, Melih Kus, G€urkan Eray Akpınar, Ozge Aksın-Artok,
)
)
)
Norbert Krause,‡ Sıla Karaca,† Nuran Elmacı,† and Levent Artok*,†
†Department of Chemistry, Faculty of Science, Izmir Institute of Technology, Urla 35430, Izmir, Turkey
‡Organic Chemistry II, Dortmund University of Technology, Otto-Hahn-Strasse 6, D-44227 Dortmund, Germany
S Supporting Information
b
ABSTRACT: Two methods involving the rhodium-catalyzed
reaction of 2-en-4-yne acetates and the palladium-catalyzed
reaction of 2-en-4-yne carbonates with organoboronic acids
were investigated; both afforded exclusively the (E)-configured
vinylallenes. The coordinative interaction of the rhodium with
the acetate group promoted the δ-elimination of Rh(I)-OAc
from the alkenylrhodium intermediate II in both syn and anti
modes, with the syn-elimination being the major path. DFT
calculations revealed that a conformer of this intermediate (II),
which can lead to the (E)-configured vinylallene product via the
syn-elimination mode, is energetically the most favorable
conformer. The rhodium-catalyzed procedure is not applicable to reactions involving (E)-configured enyne acetates, because the
geometry of the alkenylrhodium intermediate that is derived from the corresponding (E)-enyne acetate would not allow such
coordinative interaction to occur. The palladium-catalyzed method, which proceeds through formation of the σ-vinylallenylpalla-
dium intermediate, B, is suitable for both the (E)- and (Z)-configured enyne carbonates and appears to have a wider scope for both
organoboronic acids and enyne substrates. The palladium-catalyzed reaction of an enantiomerically enriched enyne carbonate
proceeded with racemization.
’ INTRODUCTION
Organoboron reagents, particularly those bearing aryl and
alkenyl units, are convenient and versatile reagents because they
are widely available, thermally stable, inert to water and oxygen,
relatively nontoxic, and tolerant to a wide range of reactive
functional groups.2 For these reasons, organoboron reagents are
often used, with convenience, in transition-metal-catalyzed CꢀC
bond-forming reactions.2a,3
Some of the leading applications in the use of organoboron
reagents as a source for soft nucleophiles are4 the rhodium(I)-
catalyzed conjugate addition of aryl- or alkenylboronic acids to
R,β-unsaturated reagents,4,5 addition of arylboronic acids to
aldehydes via Rh(I) catalysis (which is an alternative to the
commonly known Grignard reaction),6 Rh(I)-catalyzed hydro-
arylation of internal alkynes with aryl- or alkenylboronic
reagents,7 1,3-SN20-type substitution reactions of propargylic
reagents leading to allenic products,8 and Rh(I)-catalyzed ring-
opening reactions of oxabicyclic alkenes with organoborons.9
It has been previously established that conjugated enynes with
a leaving group at the allylic position undergo 1,5-(SN200)-
substitution with organometallic nucleophiles leading to vinylal-
lenes (Scheme 1).
Grignard, organocopper, organolithium, and organozinc re-
agents are traditional nucleophilic organometallic reagents that
are used for carbonꢀcarbon coupling reactions. However, these
reagents are highly moisture- and air-sensitive, have very short shelf-
lives, and can tolerate only few electrophilic groups. Hence, use of
these organometallic reagents requires protection of electrophilic
functional groups, strict anhydrous conditions, and an inert
atmosphere.
For these reasons, there has been an increasing trend toward
adopting reagents that are relatively cheap, easy-to-handle, and
tolerant to a wide range of functionalities and solvents during
CꢀC bond-forming reactions. Importantly, the rather lower
reactivity of these reagents is compensated by performing the
reactions in the presence of transition metal catalysts.
A classical example of these efforts is transition-metal-
catalyzed biaryl-forming reactions. Kumada, Negishi, Stille, and
Suzuki couplings are well-known transition-metal-catalyzed
reactions. All of them involve the coupling of aryl halides or
pseudoaryl halides with different types of organometallic re-
agents. Among them, the Suzuki reaction is the most popular and
has found wide application in industrial processes and in
laboratory syntheses since it utilizes organoboron reagents that
have several advantages over its competitors.1
Received: February 2, 2011
Published: June 12, 2011
r
2011 American Chemical Society
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Scheme 1. Reaction of 2-En-4-yne Reagents and Organometals
Table 1. Effect of Base and Water Additives on the
Rh(I)-Catalyzed Reaction of (Z)-Enyne Acetate 1.1a
with Phenylboronic Acid
Scheme 2. Palladation of 2-En-4-yne Carbonate Leading to
σ-Vinylallenylpalladium(II) Species
entry
base (equiv)
water (mL) conversion (%)a yield, 3aa (%)a
1b
2
KOH (3)
CsF (3)
0.1
0.1
0.1
0.1
0.1
78
100
100
100
95
58
55
75
85
75
20
67
42
38
50
40
3
CsF (2)
4
CsF (1.5)
CsF (1.1)
CsF (1.5)
CsF (1.5)
CsF (1.5)
KF (3)
5
Gorꢀe and Dulcere found that the reaction of 2,4-enyne halides
with methylmagnesium iodide or trimethylsilylmagnesium chlor-
ide (or trimethylsilyllithium) proceeds via an SN200-type nucleo-
philic substitution yielding an E/Z mixture of vinylallenes.10 The
method, however, is not general, since other Grignard reagents
completely failed to form the desired vinylallenes. Krause et al.
devised a more general method; they determined that (E)-2-en-
4-yne acetates can effectively undergo SN200 type alkylation
with various lithium cuprates affording an E/Z mixture of
vinylallenes.11
6
25
7
0.05
0.2
0.1
0.1
0.1
77
8
55
9
40
10
11
CsOH (1.5)
100
82
Cs2CO3 (1.5)
1
a Determined by H NMR using benzaldehyde as internal standard.
b Rhodium complex charged was [RhCl(cod)]2.
However, to the best of our knowledge, there has been no
report involving any 1,5-substitution reactions of 2,4-enynes with
organoboron reagents,12 and therefore it was our intention to
introduce the transition-metal-catalyzed organoboronic combi-
nation as a new method for the arylative and alkenylative
reactions of 2-en-4-yne reagents. A part of our related study
discloses that organoboron reagents can also be utilized as a
nucleophilic aryl source for conjugated enyne acetates in the
presence of a rhodium(I) complex to provide vinylallenes.
Another part of this report involves studies on the Pd(0)-
catalyzed reaction of organoboronic acids with conjugated en-
ynes bearing a carbonate substituent in the allylic position. We
have recently reported that the Pd(0)-catalyzed carbonylation of
carbonates of secondary (Z)-2-en-4-yne alcohols in the presence
of CO in an alcohol medium proceeded through the formation of
a σ-vinylallenylpalladium(II) complex (B) leading with high
selectivity to 2,3,5-trienoates, while showing no traces of allylic
substitution products (Scheme 2).13
Table 2. Rh(I)-Catalyzed Reaction of the (Z)-Enyne Acetate
1.1a with Arylboronic Acids
entry
Ar
product
yield (%)
1
2
3
4
5
6
7
8
9
2a Ph
3aa
3ab
3ac
3ad
3ae
3af
82
76
77
83
86
77
83
76
81
2b 4-CF3C6H4
2c 4-MeCOC6H4
2d 4-MeC6H4
2e 3-MeC6H4
2f 3-ClC6H4
It has been already shown that σ-allenylpalladium(II) species
are also reactive toward transmetalation-type reactions with
organoboronic acids leading to arylallenes.14 To this end, we
purposely investigated the Pd(0)-catalyzed 1,5-substitution
reactivity of the 2,4-enyne carbonates with organoboronic
reagents.
2g 2-MeOC6H4
2h 2-naphthyl
2i 3-thienyl
3ag
3ah
3ai
nonseparable intricate isomers of the vinylallene with unassigned
structures (Table 1, entry 1).
The reaction halted after a period of time, and the conversion
was incomplete even with higher loadings of Rh at the beginning
of the reaction, indicating that a change in the composition of the
reaction medium (possibly due to an increased concentration of
the acetate dispelled from the enyne substrate) lowered the
activity of the rhodium significantly.
The complete conversion of (Z)-1.1a could be attained by
substituting the base with CsF (entry 2) in the presence of
[RhOH(cod)]2 complex. The formation of isomeric byproducts
’ RESULTS AND DISCUSSION
Rh(I)-Catalyzed Reaction of 2-En-4-yne Acetates and Or-
ganoborons. The reaction of a (Z)-configured enyne acetate
1.1a with 3 equiv of phenylboronic acid proceeded in THF
solvent, at room temperature, and in the presence of
[RhCl(cod)]2 (6% Rh), 3 equiv of KOH, and 0.1 mL of water
to yield the desired phenyl-substituted vinylallene 3aa product,
which however was accompanied by significant amounts of
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Table 3. Rh(I)-Catalyzed Reaction of (Z)-Enyne Acetates
with Phenylboronic Acid
the dual coordinative interaction of rhodium with alkynyl and
acetate moieties (I), to afford the alkenylrhodium(I) intermedi-
ate (II) (Scheme 3).7,8 It should be noted that the application of
the rhodium-catalyzed protocol on enynes 4 and 5, which lack a
leaving group at the allylic carbon, resulted in complex mixtures
of various isomers of mono- and diarylated products.
entry
substrate
R1
R2
R3
product
isolated yield (%)
The subsequent δ-elimination of [Rh]-OAc and double bond
migration may take place concurrently via both anti and syn
modes,20 syn-deacetylation being the major path, to produce the
enantiomers of arylated vinylallene products and regenerating
the active Rh(I) catalyst for the next cycle. Alternatively, the
formation of a benzylidene-π-allylrhodium intermediate (III)
may precede the deacetylation step.12,19
1
2
3
4
5
6
(Z)-1.1b
(Z)-1.1c
(Z)-1.1d
(Z)-1.1e
(Z)-1.1f
(Z)-1.1g
Bu
Cy
Bu
Bu
Me
Me
Me
Me
Bu
Me
Me
Me
Me
Bu
3ba
3ca
3da
3ea
3fa
72
70
75
73
79
77
Ph
Me
Me
i-Pr
3ga
However, in both instances, the elimination step should be
activated via the coordination of the rhodium and the oxygen
functionality.20 Indeed, we found that the Rh-mediated protocol
is not applicable to (E)-configured enyne acetates; an analogous
reaction with (E)-1.1a furnished a dienyl acetate structure (6) as
the major product (62% NMR yield), and consequently, forma-
tion of the desired vinylallene product was less than 10%
(Scheme 4). This result indicates that the alkenylrhodium
intermediate II0, which is formed via rhodoarylation of (E)-
1.1a, could not undergo the δ-elimination of [Rh]-OAc, pre-
ferring instead demetalation to yield a hydroarylated product
(6).7 The intermediate II0 cannot maintain a suitable geometry
that is amenable to interaction with Rh(I)-OAc, this being a
suspected prerequisite to the elimination step.
For better rationalization of the observed enantioselective
outcome of the rhodium-mediated reaction of (R,Z)-1.1a with
phenylboronic acid, we performed conformational analyses by
carrying out density functional theory (DFT) calculations for
intermediate II. The conformations were investigated by con-
sidering different combinations of rotations about four different
single carbonꢀcarbon bonds (Θ1ꢀΘ4), as depicted in Figure 1,
and 81 conformers were obtained. Then, more rotations were
performed so as to achieve conformers that included the rhodium
and the acetate groups in suitable relative proximity to one other
for effective coordination (typically 2.239ꢀ2.286 Å), a necessary
condition for the subsequent Rh-OAc elimination step leading
to 3.
The overall conformational analysis yielded a minimum
energy that was associated with the conformer ES as shown in
Figure 2. Interestingly, this conformer could potentially follow a
[Rh]-OAc elimination path leading to the product (S)-3aa. The
other structures, which are assigned the identifiers ER, ZS, and
ZR (Figure 2), represent the conformers of local minimum
energies and potentially lead to the products (E,R)-, (Z,S)-, and
(Z,R)-3aa, respectively. The fact that the conformer ER had a
potential energy that is 4.1 kcal/mol higher than that of the
conformer ES may account for the resulting enantiomeric ratio of
the 3aa products. The relative energies of ZR and ZS as
compared to ES are about 6.9 and 8.8 kcal/mol higher, respec-
tively. It should be noted that no (Z)-configured vinylallene
production was observed in the course of this study.
could be minimized and thereby high yields of 3aa product could
be achieved by decreasing the CsF addition to 1.5 equiv (entries
2ꢀ5). The fine adjustment of the amount of added water seemed
highly critical for the effectiveness of the process; the arylative
substitution reaction did not proceed to completion when the
reaction medium contained less or higher than 0.1 mL of water
(entries 6ꢀ8). KF salt could not be an alternative flouride source
(entry 9), and the use of other Cs compounds instead of CsF was
useless (entries 10 and 11).15
The above-shown finding represents the first example of an
arylative SN200-type reaction for 2-en-4-yne reagents. In contrast
to their transformation with organocopper and Grignard re-
agents, the resulting vinylallene had the vinylic group exclusively
in (E)-configuration.
Having established the effective conditions, an array of sub-
stituted boronic acids were then subjected to the reactions with
the enyne acetate (Z)-1.1a (Table 2). The reaction tolerated
both electron-withdrawing and -donating groups on the meta and
para positions, giving rise to high yields of the corresponding
arylated vinylallene products 3aaꢀ3af (entries 1ꢀ6). A sterically
congested organoboronic acid (2g), 2-naphthylboronic acid, and
3-thienylboronic acid were also suitable components for the
reaction, yielding related products 3agꢀ3ai with isolated yields
in the range of 76ꢀ83% (entries 7ꢀ9).16
The scope of the arylation method was also surveyed for a
range of acetates of secondary (Z)-enynols. The method ap-
peared suitable for the enyne acetates bearing butyl ((Z)-1.1b)
or cyclohexyl ((Z)-1.1c) groups on the alkynyl moiety (R1,
Table 3, entries 1 and 2), butyl ((Z)-1.1d), or phenyl ((Z)-1.1e)
groups in the R2 position (entries 3 and 4) and butyl ((Z)-1.1f)
or isopropyl ((Z)-1.1g) groups on the allylic carbon (R3, entries
5 and 6), affording the corresponding vinylallenes in good yields
when reacted with phenylboronic acid (70ꢀ79%).17
The Rh(I)-catalyzed reaction of the acetate of an enantio-
merically enriched enynol reagent, (R,Z)-1.1a (94.5% ee) with
phenylboronic acid under the optimal conditions proceeded with
partial racemization and yielded (S)-(+)-vinylallene as the major
enantiomer (82% isolated yield, 40% ee, [R]25D = +0.33 (c 0.29,
CHCl3)) (Scheme 3).18,19
The reaction should involve the regioselective cis-1,2-addition
of the in situ generated phenylrhodium(I) species across the
carbonꢀcarbon triple bond, which should be directed through
Pd(0)-Catalyzed Reaction of 2-En-4-yne Carbonates and
Organoborons. The catalyst system used for the Pd(0)-catalyzed
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Scheme 3. Machanism and Stereochemistry of Rh(I)-Catalyzed Arylation of (R,Z)-2-En-4-yne Acetate 1.1a
Scheme 4. Rh(I)-Catalyzed Arylation of (E)-1.1a
σ-vinylallenylpalladium(II) intermediate and its subsequent trans-
metalation with the organoboronic acid (Schemes 2 and 5).
The presence of small amounts of water seems beneficial for
the reaction; with its presence, the reaction of the enyne
carbonate (Z)-1.2a with phenylboronic acid proceeded with
complete conversion to give the 3aa in high yields (entries 2
and 3). The application of a lower reaction temperature (50 °C)
significantly reduced the efficacy of the process (entry 4), and the
method can also be run at a lower Pd loading (2 mol %) (entry 5).
The scope of the Pd(0)-catalyzed method appears to be
remarkably wider for both organoboronic acid and enyne
carbonate substrate partners as compared to the Rh(I)-catalyzed
version. The reaction of (Z)-1.2a with the highly electron-
deficient p-CF3 (2b) or 3,4-difluoro substituted phenylboronic
(2j) acids and 3-pyridylboronic acid (2k) afforded moderate
yields of vinylallene products (Table 5, entries 1ꢀ3). Never-
theless the reactions with ortho-, para-, and meta-substituted
electron-rich and moderately electron-poor phenylboronic acids,
1- and 2-naphthylboronic acids (2m and 2h, respectively), as well
as 3-thienylboronic acid (2i) provided the corresponding ary-
lated vinylallene products at yields ranging between 73% and
92% within relatively short reaction times (typically 1 h) (entries
4ꢀ11). In contrast to the Rh(I)-catalyzed version, alkenylboro-
nic acids also proved to be an applicable class of organoboron
reagents for the proposed Pd(0)-catalyzed method. A divinylal-
lene structure 3an was produced at a yield of 74% when (Z)-1.2a
reacted with 1-pentenylboronic acid for 1 h (entry 12).
Figure 1. Rotational angles on the structure of intermediate II, which
was used in conformational search (hydrogen atoms are omitted for
clarity).
reactions of 2,4-enyne carbonates with organoboronic acids was
Pd2(dba)3CHCl3/PPh3, since this combination already proved its
activity for Pd(0)-catalyzed alkoxycarbonylation of conjugated (Z)-
enyne carbonates, which led to vinylallenyl esters.13 Indeed, a
related (E)-configured and phenyl-functionalized vinylallene 3aa
was produced via the reaction of a (Z)-2-en-4-yne carbonate
1.2a with phenylboronic acid in the presence of Pd2-
(dba)3CHCl3 (3 mol % Pd) and PPh3 (12 mol %) in dry
THF and at 65 °C, albeit the reaction did not proceed to completion
(Table 4, entry 1). The formation of 3aa dictates formation of a
The methodology can tolerate without problem phenyl ((Z)-
1.2h), butyl ((Z)-1.2b), cyclohexyl ((Z)-1.2c), as well as highly
bulky tert-butyl ((Z)-1.2i) groups on the alkynyl terminus of the
enyne carbonates (R1, Table 6, entries 1ꢀ4). Their reaction with
phenylboronic acid under the optimal conditions provided the
corresponding vinylallenes in good to high yields (58ꢀ88%). A
moderate yield (50%, entry 5) of the vinylallene 3ja was produced
when R1 is H ((Z)-1.2j). The product 3ja, nonetheless, was
formed at a higher yield (82%, entry 6) from the reaction of the
(Z)-enyne carbonate where R1 was a SiMe3 group ((Z)-1.2k)
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Figure 2. Optimized conformers for the intermediate II (hydrogen atoms are omitted for clarity and the energy values are relative energies).
Table 4. Effect of Reaction Conditions on the
Pd(0)-Catalyzed Reaction of the (Z)-Enyne
Carbonate 1.2a with Phenylboronic Acid
Scheme 5. Transmetalation of σ-Vinylallenylpalladium(II)
and Organoboronic Acid
group ((Z)-1.2d) had no significant effect on the activity of the
enyne carbonate substrate (80% yield, entry 7); however, the
corresponding vinylallene yields wererelatively lower whenR2 was
H ((Z)-1.2l) or a phenyl group ((Z)-1.2e) (61% and 64%, entries
8 and 9, respectively).
(Z)-1.2a THF/water
entry (mmol)
(mL)
time (h) conversion (%) yield (%)a
1
0.1
0.1
0.2
0.2
0.1
2.5:0
2.5:0.2
5:0.4
6
2
71
100
100
50
67
89
(84)b
The effect of variation of allylic substitution on the activity of
the enyne carbonate was also assessed. The method was rather
successful also for the enyne substrates in which R3 was butyl
((Z)-1.2f, 76%) or isopropyl ((Z)-1.2g, 92%) groups; how-
ever, an enyne carbonate of a primary alcohol (R3 = H) led to
a low yield of (44%) of vinylallene product 3ma (entries
10ꢀ12).
2
3
1
4c
5d
5:0.4
23
43
2.5:0.2
2
100
85
a Determined by H NMR using benzaldehyde as internal standard.
1
b Isolated yield. c 50 °C. d 2% Pd and 8% PPh3.
In contrast to the Rh-mediated procedure, the Pd-catalyzed
method was also successful when used with (E)-configured 2,4-
enyne carbonates (Table 7); (E)-1.2a afforded the vinylallene
product 3aa in a yield of 69%, which is somewhat lower than that
upon the involvement of a desilylation process (entry 6).21
Substituting the methyl group in the R2 position with a butyl
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Table 5. Pd(0)-Catalyzed Reaction of the (Z)-Enyne
Carbonate 1.2a with Organoboronic Acids
Table 7. Pd(0)-Catalyzed Reaction of the (E)-Enyne
Carbonate 1.2a with Organoboronic Acids
entry
R
time (h)
product
yield (%)
entry
R
time (h)
product
yield (%)
1
2a Ph
1
1
3aa
69
69
25
61
81
77
76
75
77
71
77
71
74
2a
3b
4
1
2b 4-CF3C6H4
2j 3,4-F2C6H4
2k 3-pyridyl
8
24
6
3ab
3aj
56
58
59
79
92
80
88
82
75
83
73
74
6
2
2b 4-CF3C6H4
2c 4-MeCOC6H4
2d 4-MeC6H4
2e 3-MeC6H4
2g 2-MeOC6H4
2l 2-FC6H4
5
3ab
3ac
3ad
3ae
3ag
3al
3
3ak
3ac
3ad
3ae
3ag
3al
5
10
1
4
2c 4-MeCOC6H4
2d 4-MeC6H4
2e 3-MeC6H4
2g 2-MeOC6H4
2l 2-FC6H4
2
6
5
1
7
1
6
1
8
1
7
1
9
1
8
1
10
11
12
13
2m 1-naphthyl
2i 3-thienyl
1
3am
3ai
9
2h 2-naphthyl
2m 1-naphthyl
2i 3-thienyl
1
3ah
3am
3ai
1
10
11
12
1
2k 3-pyridyl
10
1
3ak
3an
1
2n 1-pentenyl
2n 1-pentenyl
1
3an
a 50 °C. b RT.
Table 6. Pd(0)-Catalyzed Reaction of (Z)-Enyne Carbonates
with Phenylboronic Acid
Table 8. Pd(0)-Catalyzed Reaction of (E)-Enyne Carbonates
with Phenylboronic Acid
entry
substrate
R1
Ph
R2
R3
product
yield (%)
88
entry
substrate
R1
R2
R3
product
yield (%)
1
(Z)-1.2h
(Z)-1.2b
(Z)-1.2c
(Z)-1.2i
(Z)-1.2j
(Z)-1.2k
(Z)-1.2d
(Z)-1.2l
(Z)-1.2e
(Z)-1.2f
(Z)-1.2g
(Z)-1.2m
Me
Me
Me
Me
Me
Me
Bu
Me
Me
Me
Me
Me
Me
Me
Me
Me
Bu
3ha
3ba
3ca
3ia
1
2
3
4
5
(E)-1.2b
(E)-1.2h
(E)-1.2f
(E)-1.2g
(E)-1.2n
Bu
Me
Me
Me
Me
H
Me
Me
Bu
3ba
3ha
3fa
78
87
2
Bu
82
Ph
3
4a
Cy
67
Me
Me
Me
75
t-Bu
H
58
i-Pr
Me
3ga
3na
83
5
3ja
50
<10
6
Me3Si
Bu
3ja
82 (R1 = H)b
7
3da
3la
80
61
64
76
92
44
Scheme 6. Mechanism and Stereochemistry of Pd(0)-Cata-
lyzed Arylation of (R,Z)-2-En-4-yne Carbonate 1.2a
8
Bu
H
9
Bu
Ph
3ea
3fa
10c
11
12
Me
Me
Bu
Me
Me
Me
i-Pr
H
3ga
3ma
a 3 h. b Desilylated product. c 2 h.
obtained from its (Z)-configured isomer when reacted with
phenylboronic acid at 65 °C for 1 h (entry 1). Nevertheless, in
contrast with the reactivity of (Z)-1.2a, the same yield could also
be achieved at 50 °C (entry 2); however, at this lower reaction
temperature, the conversion was incomplete when using (Z)-
1.2a (see Table 4, entry 4). The activity of the Pd-catalysis,
however, was insufficient at room temperature; the conversion
was low and consequently gave rise to a small yield of the desired
vinylallene product (entry 3).
(E)-1.2a reacted with various electron-rich and electron-poor,
as well as sterically encumbered phenylboronic acids successfully
to produce the related vinylallenes in good yields (entries 4ꢀ9).
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1-Napthyl, heteroaryl, and alkenylboronic acids were also suita-
ble components (entries 10ꢀ13).
ethynyltrimethylsilane with a corresponding vinyl iodide reagent as
described elsewhere.13 The enyne carbonate containing a terminal
alkynyl group ((Z)-1.2j) was obtained via desilylation27 of a correspond-
ing Me3Si substituted 2,4-enynol ((Z)-4-methyl-6-(trimethylsilyl)hex-
3-en-5-yn-2-ol) and the following conversion of the hydroxyl group to
carbonate. The methods for the syntheses of all other (Z)-enyne
carbonates are described elsewhere.13 Acetates and carbonates of (E)-
2-en-4-yn-1-ols were synthesized following the described methods
starting from (E)-pent-2-en-4-yn-1-ol reagent.13 Racemic enyne acetates
and (S)-1.1a were prepared by acetylation11a of the corresponding
enynol reagents, which were synthesized as described previously.13 All
substrates were colorless oils.
The enyne reagents with butyl ((E)-1.2b) or phenyl substi-
tuent on the alkynyl carbon ((E)-1.h) and butyl ((E)-1.2f) or
isopropyl ((E)-1.2 g) groups on the allylic carbon all gave rise to
high yields of the corresponding vinylallene products when
reacted with phenylboronic acid (Table 8, entries 1ꢀ4). Inter-
estingly, however, the reaction of an (E)-enyne carbonate ((E)-
1.2n), where R2 is H, with phenylboronic acid, in contrast to its
analogue (Z)-configured substrate ((Z)-1.2l), gave rise to an
intricate mixture of products, containing less than 10% of the
corresponding phenylated vinylallene (entry 5).
(Z)-1.1a. 1H NMR (400 MHz, CDCl3) δ 5.71 (dq, J = 8.8, 6.8 Hz,
1H), 5.56 (dq, J = 8.8, 1.2 Hz, 1H), 2.01 (s, 3H), 1.97 (s, 3H), 1.81 (d, J =
1.2 Hz, 3H), 1.28 (d, J = 6.8 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ
No center-to-axis chirality transfer selectivity could be demon-
strated with the existing method, as is the reported case for the
Pd(0)-catalyzed alkoxycarbonylation applications with these
substrates.13 The relevant reaction of an enantiomerically en-
riched enyne carbonate (R,Z)-1.2a (94.5% ee) with phenylboro-
nic acid led to a racemic mixture of the product.
170.4, 134.9, 121.5, 91.7, 77.7, 70.3, 23.5, 21.5, 20.5, 4.5; IR (νmax
/
cmꢀ1) 2982, 2233, 1730, 1639, 1433, 1235, 1152, 1046; MS (EI, m/z)
166 (11, M+), 151 (37), 137 (4), 123 (100), 109 (92), 91 (98), 79 (33);
HRMS (EI) calcd for C10H14O2 (M+) 166.0988, found 166.0993.
The catalytic cycle should involve an oxidative cleavage
leading to a πꢀallylpalladium intermediate (A0) and subsequent
isomerization of this intermediate to A00 could be the basis for the
observed racemization (Scheme 6).22 The shift of palladium to
the distal alkynyl carbon yields a racemate of 3aa.
(Z)-1.1b. 1H NMR (400 MHz, CDCl3) δ 5.73 (dq, J = 8.4, 6.4 Hz,
1H), 5.56 (dq, J = 8.4, 1.4 Hz, 1H), 2.34 (t, J = 7.0 Hz, 2H), 2.02 (s, 3H),
1.83 (d, J = 1.6 Hz, 3H), 1.38ꢀ1.58 (m, 4H), 1.29 (d, J = 6.4 Hz, 3H), 0.92
(t, J = 7.2 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ 170.3, 134.9, 121.6,
96.4, 78.6, 70.4, 30.9, 23.6, 22.1, 21.5, 20.4, 19.3, 13.7; IR (νmax/cmꢀ1) 2941,
2870, 2223, 1736, 1636, 1371, 1232, 1036; MS (EI, m/z) 208 (8, M+), 193
(8), 179 (4), 165 (100), 151 (24), 137 (14), 123 (49), 109 (88), 91 (82), 79
(47); HRMS (EI) calcd for C13H20O2 (M+) 208.1458, found 208.1455.
’ CONCLUSION
In this report, the first examples of the transition-metal-
catalyzed 1,5-substitution reactions of 2-en-4-yne reagents with
a leaving group in the allylic position and organoboronic acids are
presented. The reactions produced vinylallenes with an exclu-
sively (E)-configuration in both Rh(I)- and Pd(0)-catalyzed
procedures. Rh(I)-catalyzed reactions proceeded via typically
SN200-type substitution of (Z)-2-en-4-yne acetates, which is
triggered by cis-addition of in situ formed nucleophilic
arylrhodium(I) species. The δ-elimination of Rh(I)-OAc, which
is promoted via coordinative interactions, took place in both syn
and anti modes, with the syn-elimination being the dominant
route. The (E)-configured enynes are not suitable reagents for
the Rh(I)-catalyzed method, since geometrical constraints pro-
hibit the required coordinative interactions. The Pd(0)-catalyzed
method can be employed for conjugated enynes that contain a
carbonate functionality in the allylic position and is applicable for
a wider range of organoboronic acids and both (E)- and (Z)-
configured enyne substrates. For an enantiomerically enriched
(Z)-enyne carbonate, the Pd(0)-catalyzed method led to com-
plete racemization, in contrast to the Rh(I)-catalyzed method.
(Z)-1.1c. 1H NMR (400 MHz, CDCl3) δ 5.78ꢀ5.66 (m, 1H), 5.56
(dq, J = 8.4, 0.8 Hz, 2H), 2.55ꢀ2.48 (m, 1H), 2.01 (s, 3H), 1.82 (d, J =
1.2 Hz, 3H), 1.83ꢀ1.76 (m, 2H), 1.66ꢀ1.74 (m, 2H), 1.43ꢀ1.53 (m,
3H), 1.30ꢀ1.37 (m, 3H), 1.35 (d, J = 5.6 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 170.3, 134.8, 128.6, 121.8, 100.5, 78.5, 70.3, 63.4, 32.8,
29.8, 26.0, 24.9, 23.6, 21.5, 20.4; IR (νmax/cmꢀ1) 2971, 2929, 2854,
2212, 1737, 1448, 1368, 1234, 1153, 1041; MS (EI, m/z) 234 (10, M+),
219 (12), 191 (89), 177 (19), 149 (26), 131 (31), 117 (24), 109 (100),
91 (51), 77 (25); HRMS (EI) calcd for C15H22O2 (M+) 234.1614,
found 234.1616.
’ EXPERIMENTAL SECTION
(Z)-1.1d. 1H NMR (400 MHz, C6D6) δ 6.25 (dq, J = 8.4, 6.4 Hz,
1H), 5.67 (d, J = 8.8 Hz, 1H), 2.15 (t, J = 6.8 Hz, 2H), 2.11 (t, J = 8.0 Hz,
2H), 1.69 (s, 3H), 1.56 (quint, J = 7.6 Hz, 2H), 1.42ꢀ1.31 (m, 4H), 1.38
(d, J = 6.4 Hz, 3H), 1.30ꢀ1.20 (m, 2H), 0.85 (t, J = 7.2 Hz, 3H), 0.81 (t, J
= 7.2 Hz, 3H); 13C NMR (101 MHz, C6D6) δ 169.4, 135.1, 126.7, 97.1,
78.5, 70.1, 37.4, 31.1, 30.8, 22.4, 22.2, 21.0, 20.7, 19.4, 14.1, 13.7; IR
(νmax/cmꢀ1) 2955, 2932, 2865, 2216, 1742, 1631, 1457, 1369, 1237,
1041; MS (EI, m/z) 250 (3, M+) 235 (10), 221 (3), 207 (80), 190 (28),
161 (33), 151 (68), 133 (48), 119 (51), 105 (100), 91 (98), 77 (34);
HRMS (EI) calcd for C16H26O2 (M+) 250.1927, found 250.1928.
General. The synthesized reactants and vinylallene products were
analyzed by GC and GCꢀMS and isolated by column chromatography
using a hexane/ethyl acetate eluent. The vinylallene products are
colorless or light yellow oil, and coupling constants of olefinic protons
and NOE studies confirmed (E)-configured structures. NMR spectra
were recorded within CDCl3 or C6D6 solvents.23 Infrared spectra were
obtained by ATR method with neat samples. Enantiomeric excess values
were determined by an HPLC method with an OD column (25 cm ꢁ
0.46 cm) and using hexane eluent (1 mL/min; racemic (Z)-3aa eluted at
the retention times of 4.0 (R) and 4.2 (S) minutes). The Pd2-
(dba)3CHCl3,24 [RhCl(cod)]2,25 and [RhOH(cod)]226 complexes were
synthesized in laboratory.
Preparation of the Enyne Substrates. The synthesis of
enyne carbonate (Z)-1.2k involved the Sonogashira coupling of
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1
(Z)-1.1e. 1H NMR (400 MHz, C6D6) δ 7.70ꢀ7.65 (m, 2H), 7.17ꢀ
7.04 (m, 3H), 6.42 (dq, JAB= 8.4, 6.4 Hz, 1H), 6.34 (d, JAB = 8.4 Hz, 1H),
2.18 (t, J = 6.8 Hz, 2H), 1.70 (s, 3H), 1.44ꢀ1.29 (m, 4H), 1.42 (d, J = 6.4
Hz, 3H), 0.81 (t, J = 7.2 Hz, 3H); 13C NMR (101 MHz, C6D6) δ 169.4,
138.2, 135.3, 128.7, 128.4, 126.7, 126.2, 99.2, 77.4, 70.4, 31.0, 22.3, 20.9,
20.5, 19.5, 13.7; IR (νmax/cmꢀ1) 2960, 2932, 2865, 2233, 1739, 1368, 1234,
1039, 761, 693; MS (EI, m/z) 270 (6, M+) 255 (6), 227 (63), 211 (16), 185
(42), 167 (100), 153 (94), 141 (33), 128 (34), 115 (37), 91 (23), 77 (14);
HRMS (EI) calcd for C18H22O2 (M+) 270.1614, found 270.1613.
(E)-1.1a. H NMR (400 MHz, CDCl3) δ 5.65 (d, JAB = 9.2, 1H),
5.54ꢀ5.61 (dq, JAB = 8.8, 6.4 Hz, 1H), 2.01(s, 3H), 1.93(s, 3H), 1.85 (d,
J = 0.8 Hz, 3H), 1.27 (d, J = 6.4 Hz, 3H); 13C NMR (100 MHz, CDCl3)
δ 170.4, 134.8, 121.8, 84.7, 81.8, 67.5, 21.4, 20.5, 18.2, 4.3; FTIR (νmax
/
cmꢀ1) 2980, 2918, 2228, 1731, 1638, 1443, 1370, 1234, 1154, 1040,
1015, 943, 864, 610; MS (EI, m/z) 166 (13, M+), 151 (30), 123 (100),
109 (79), 91 (87), 79 (26).
(E)-1.2a. 1H NMR (400 MHz, CDCl3) δ 5.66 (d, J = 9.2 Hz, 1H),
5.43 (dq, J = 9.2, 6.4 Hz, 1H), 3.75 (s, 3H), 1.92 (s, 3H), 1.87 (d, J =
1.2 Hz, 3H), 1.33 (d, J = 6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
(Z)-1.1f. 1H NMR (400 MHz, C6D6) δ 6.12 (dt, J = 8.4, 6.8 Hz, 1H),
5.55 (dq, J = 8.6, 1.0 Hz, 1H), 1.83ꢀ1.74 (m, 2H), 1.76 (d, J = 1.2 Hz,
3H), 1.72 (s, 3H), 1.60 (s, 3H), 1.38ꢀ1.25 (m, 4H), 0.84 (t, J = 7.2 Hz,
3H); 13C NMR (101 MHz, C6D6) δ 169.4, 134.7, 122.6, 91.8, 78.6, 73.3,
34.9, 27.6, 23.6, 22.9, 20.9, 14.2, 4.05; IR (νmax/cmꢀ1) 2958, 2922, 2857,
2232, 1738, 1634, 1363, 1371, 1234, 1018, 953; MS (EI, m/z) 208 (5,
M+), 193 (14), 165 (59), 151 (43), 123 (28), 109 (100), 91 (49), 79
(32); HRMS (EI) calcd for C13H20O2 (M+) 208.1458, found 208.1456.
155.3, 134.0, 122.4, 85.0, 81.7, 71.6, 54.7, 20.5, 18.2, 4.3; FTIR (νmax
/
cmꢀ1) 2981, 2957, 2920, 2853, 2227, 1742, 1639, 1441, 1327, 1255,
1154, 1034, 938, 898, 864, 791; MS (EI, m/z) 182 (13, M+), 167 (5), 123
(100), 107 (84), 91 (99), 79 (62).
(E)-1.2b. 1H NMR (400 MHz, CDCl3) δ 5.67 (d, J = 8.8 Hz 1H),
5.48 (dq, J = 8.8, 6.5 Hz, 1H), 3.75 (s, 3H), 2.29 (t, J = 7.0 Hz, 2H), 1.88
(s, 3H), 1.50 (quint, J = 6.8 Hz, 2H), 1.41 (sext, J = 7.6 Hz, 2H), 1.34 (d,
J = 6.4 Hz, 3H), 0.92 (t, J = 7.2 Hz, 3H); 13C NMR: (101 MHz, CDCl3)
δ 155.3, 133.9, 122.5, 89.6, 82.6, 71.7, 54.7, 30.9, 22.1, 20.5, 19.1, 18.3,
13.7; FTIR (νmax/cmꢀ1) 2958, 2933, 2873, 2220, 1743, 1638,
1441, 1326, 1257, 1154, 1036, 939, 865, 792; MS (EI, m/z) 224 (6,
M+), 182 (9), 165 (70), 149 (50), 133 (19), 119 (41), 105 (77), 91
(100), 77 (53).
(Z)-1.1g. 1H NMR (400 MHz, C6D6) δ 6.01 (dd, J = 8.8, 6.4 Hz,
1H), 5.55 (dq, J = 8.8, 0.8 Hz, 1H), 1.98 (octet, J = 6.8 Hz, 1H), 1.77 (d,
J = 1.6 Hz, 3H), 1.72 (s, 3H), 1.60 (s, 3H), 0.98 (d, J = 6.8 Hz, 3H), 0.95
(d, J = 6.8 Hz, 3H); 13C NMR (101 MHz, C6D6) δ 169.3, 132.7, 123.6,
91.7, 78.8, 77.4, 33.0, 23.8, 20.8, 18.4, 18.1, 4.10; IR (νmax/cmꢀ1) 2963,
2920, 2876, 2240, 1733, 1637, 1435, 1369, 1232, 1017, 972, 606; MS (EI,
m/z) 194 (4, M+), 179(2), 151(41), 137(8), 119(24), 109 (100), 91 (15),
79 (13); HRMS (EI) calcd for C12H18O2 (M+) 194.1301, found 194.1307.
1
(E)-1.2f. H NMR (400 MHz, CDCl3) δ 5.62 (d, J = 9.2, 1H),
5.26ꢀ5.32 (m, 1H), 3.75 (s, 3H), 1.93 (s, 1H), 1.88 (d, J = 1.2 Hz, 3H),
1.68ꢀ1.77 (m, 1H), 1.49ꢀ1.58 (s, 1H), 1.37ꢀ1.24 (m, 4H), 0.88 (t, J =
6.6 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ 155.4, 133.1, 123.2, 85.0,
(Z)-1.2j. 1H NMR (400 MHz, C6D6) δ (dq, J = 8.0, 6.5 Hz, 1H), 5.56
(d, J = 8.0 Hz, 1H), 3.34 (s, 3H), 2.80 (s, 1H), 1.58 (d, J = 1.2 Hz, 3H),
1.26 (d, J = 6.4 Hz, 3H); 13C NMR (101 MHz, C6D6) δ 155.6, 138.0,
120.4, 83.4, 81.4, 73.8, 54.1, 22.7, 20.2; FTIR (νmax/cmꢀ1) 2957, 2931,
2860, 2244, 146 1441, 1258, 1033, 944, 791, 762, 697; MS (EI, m/z) 168
(2, M+), 153(4), 109(100), 91(77), 77(44); HRMS (EI) calcd for
C9H12O3 (M+) 168.0781, found 168.0780.
82.0, 75.2, 55.0, 34.2, 27.1, 23.0, 18.4, 14.1, 4.3; FTIR (νmax/cmꢀ1
)
2957, 2930, 2862, 2222, 1743, 1638, 1441, 1380, 1321, 1259, 1152, 1091,
1036, 933, 879, 866, 791; MS (EI, m/z) 224 (4, M+), 167 (31), 148 (26),
133 (19), 123 (38), 119 (51), 105 (47), 91 (94), 77 (56).
(E)-1.2g. 1H NMR (400 MHz, CDCl3) δ 5.63 (d, J = 9.6 Hz, 1H),
5.07 (dd, J = 9.6, 7.0 Hz, 1H), 3.75 (s, 3H), 1.93 (s, 3H), 1.89 (d, J = 1.2
Hz, 3H), 0.95 (d, J = 6.8 Hz, 3H), 0.90 (d, J = 6.8 Hz, 3H); 13C NMR
(100 MHz, CDCl3) δ 155.6, 131.5, 124.0, 85.0, 81.9, 79.6, 54.8, 32.5,
18.5, 18.3, 17.9, 4.3; FTIR (νmax/cmꢀ1) 2960, 2920, 2876, 2222, 1743, 1639,
1441, 1254, 966, 934, 791; MS (EI, m/z) 210 (9, M+), 195 (3), 167 (100),
151 (85), 135 (41), 123 (42), 119 (92), 108 (71), 91 (82), 77 (59).
1
(Z)-1.2k. H NMR (400 MHz, CDCl3) δ 5.70 (dq, JAB = 8.8,
1.6 Hz, 1H), 5.62 (dq, J = 6.4, 1.2 Hz, 1H), 3.76 (s, 3H), 1.85 (d, J =
0.8 Hz, 3H), 1.37 (d, J = 6.8 Hz, 3H), 0.2 (s, 9H); 13C NMR
(100 MHz, CDCl3) δ 155.1, 136.9, 121.4, 102.7, 100.5, 74.1, 54.7,
23.0, 20.1, ꢀ0.01; FTIR (νmax/cmꢀ1) 2958, 2147, 1747, 1442, 1254,
1036, 880, 837, 791, 760, 634; MS (EI, m/z) 240 (12, M+), 225 (3),
197 (3), 181 (100), 165 (35), 149 (88), 136 (13), 121 (22), 107 (12),
97 (23), 89 (64), 73 (63), 59 (33); HRMS (EI) calcd for C12H20O3Si
(M+) 240.1176, found 240.1165.
(E)-1.2h. 1H NMR (400 MHz, CDCl3) δ 7.41ꢀ7.45 (m, 2H),
7.28ꢀ7.33 (m, 3H), 5.87 (dq, J = 8.8, 1.2 Hz, 1H), 5.50 (dq, J = 8.8, 6.4
Hz, 1H), 3.77 (s, 3H), 2.00 (d, J = 1.2 Hz, 3H), 1.39 (d, J = 6.4 Hz, 3H);
13C NMR (101 MHz, CDCl3) δ155.3, 135.5, 131.7, 128.4, 123.3, 121.9,
91.3, 88.5, 71.6, 54.8, 20.4, 18.0; FTIR (νmax/cmꢀ1) 3059, 2982, 2956,
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2923, 1741, 1489, 1441, 1328, 1255, 1142, 1036, 942, 866, 754, 690; MS
(EI, m/z) 244 (6, M+), 185 (100), 167 (90), 153 (95), 152 (88), 141
(44), 128 (38), 115 (54), 102 (22), 91 (35), 77 (36).
Hz, 1H), 2.1(s, 3H), 1.91 (s, 3H), 1.79 (dd, J = 6.8, 1.6 Hz, 3H); 1H NMR
(400 MHz, C6D6) δ7.35 (d, J = 8.4Hz, 2H), 7.20 (d, J = 8.4 Hz, 2H), 6.08
(dd, J = 15.2, 1.6 Hz, 1H), 5.50 (dq, J = 15.6, 6.4 Hz, 1H), 1.87 (s, 3H),
1.80 (s, 3H), 1.62 (dd, J = 6.8, 1.6 Hz, 3H); 13C NMR (100 MHz, CDCl3)
δ 207.8, 141.7, 128.5, 128.3 (q, J = 32 Hz), 125.9, 125.4, 125.1 (q, J = 3.9
Hz), 124.4 (q, J = 270 Hz), 102.5, 99.0, 18.3, 17.0, 15.3; 13C NMR (100
MHz, C6D6) δ 208.2, 141.9, 128.9 (q, J = 32 Hz), 128.9, 126.4, 125.5 (q, J
= 3.9 Hz), 125.0 (q, J = 263 Hz), 102.9, 99.6, 18.4, 17.0, 15.4; FTIR (νmax
/
(E)-1.2n. 1H NMR (400 MHz, C6D6) δ 5.99 (dd, JAB = 15.6, 6.8 Hz,
1H), 5.67 (d, JAB = 15.6 Hz, 1H), 5.15 (quint, J = 6.6 Hz, 1H), 3.73 (s,
3H), 1.90 (d, J = 1.6 Hz, 3H), 1.33 (d, J = 6.8 Hz, 3H); 13C NMR (100
MHz, C6D6) δ 155.0, 139.6, 112.9, 87.9, 75.4, 54.7, 20.1, 4.3; FTIR
(νmax/cmꢀ1) 2984, 2958, 2920, 2854, 2223, 1743, 1638, 1441, 1255,
1036, 941, 871, 790; MS (EI, m/z) 168 (3, M+), 153 (3), 109 (100), 91
(83), 77 (47).
cmꢀ1) 2987, 2928, 2855, 1933, 1616, 1323, 1164, 1114, 1074, 1014, 840,
607; MS (EI, m/z) 252 (100, M+), 237 (82), 222 (21), 209 (43), 197
(64), 183(26), 168 (36), 153(39), 141 (17), 128 (14), 115(13), 91(16);
HRMS (EI) calcd for C15H15F3 (M+) 252.1120, found 252.1119.
3ac. 1H NMR (400 MHz, CDCl3) δ 7.89 (d, J = 8.4 Hz, 2H), 7.43 (d,
JAB = 8.0 Hz, 2H), 6.04 (dq, JAB = 15.6, 1.6 Hz, 1H), 5.68 (dq, J = 15.2,
6.8 Hz, 1H), 2.57 (s, 3H), 2.1 (s, 3H), 1.9 (s, 3H), 1.80 (dd, J = 6.4, 1.2
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 208.3, 197.7, 143.0, 135.0,
128.43, 128.39, 125.8, 125.4, 102.4, 99.4, 26.6, 18.4, 17.0, 15.3; FTIR
(νmax/cmꢀ1) 2925, 2850, 1930, 1681, 1601, 1357, 1266, 959, 838, 646,
602; MS (EI, m/z) 226 (100, M+), 211 (57), 183 (37), 168 (43), 153
(39), 141 (24), 128 (19), 115 (21), 91 (11); HRMS (ESI) calcd for
C16H19 (MH+) 227.1430, found 227.1429.
General Method for the Rhodium-Catalyzed Synthesis of
Vinylallenes with (Z)-2-En-4-yne Acetates and Arylboronic
Acids. To an oven-dried flask containing 1.1 (0.3 mmol) and 2 (0.9
mmol, 3 equiv) was added CsF (0.45 mmol, 1.5 equiv), [RhOH(cod)]2
(6 mol % Rh), degassed water (0.1 mL), and dry THF (2.0 mL),
successively, under Ar. The reaction mixture was stirred magnetically at
room temperature for 16 h. The solvent was removed under reduced
pressure, and the residue was purified by column chromatography using
hexane/ethyl acetate as eluent to give 3.
General Method for the Palladium-Catalyzed Synthesis of
Vinylallenes with (Z)-or (E)-2-En-4-yne Carbonates and Ar-
ylboronic Acids. A mixture of Pd2(dba)3CHCl3 (3% Pd) and PPh3
(12%) in dry THF (1 mL) was stirred for 15 min under Ar. Then, the dry
THF (4 mL) solution of 1.2 (0.2 mmol), 2 (0.6 mmol, 3 equiv), and
degassed water (0.4 mL) was added successively. The mixture was
stirred magnetically in an oil bath preheated at 65 °C. The solvent was
evaporated, and the residue was purified by column chromatography on
silica gel (hexane/ethyl acetate), affording the product 3.
Computational Details. The geometry optimizations were per-
formed by using the density functional theory (DFT) with Becke three
parameter Lee, Yang, and Parr, (B3LYP)28 functional and LANL2DZ
basis set implemented in Gaussian 09 software.29 The imaginary
frequencies have been checked with the frequencies for these structures.
The geometry analysis is shown in Supporting Information for some
selected geometrical parameters. The natural Bond Orbital (NBO) and
Mulliken charges were used for the charge analysis.
3ad. 1H NMR (400 MHz, CDCl3) δ 7.24 (d, JAB = 8.0, 2H), 7.11 (d,
JAB = 8.0 Hz, 2H), 6.06 (dq, J = 16.0, 2.0 Hz, 1H), 5.64 (dq, J = 15.6, 6.4
Hz, 1H), 2.32 (s, 3H), 2.07 (s, 3H), 1.80 (s, 3H), 1.79 (dd, J = 6.8, 1.6
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 206.7, 136.1, 134.8, 129.5,
129.0, 125.7, 124.3, 101.7, 99.5, 21.1, 18.3, 17.2, 15.5; FTIR (νmax
/
cmꢀ1) 3038; 2982, 2921, 2850, 1510, 1444, 1370, 1025, 963, 816, 590;
MS (EI, m/z) 198 (100, M+), 183 (93), 168 (82), 153 (48), 141 (36),
128 (33), 115 (35), 105 (18), 91 (30), 77 (19); HRMS (ESI) calcd for
C15H19 (MH+) 199.1481, found 199.1481.
3aa. 1H NMR (400 MHz, CDCl3) δ 7.34ꢀ7.38 (m, 2H), 7.28ꢀ7.33
(m, 2H), 7.14ꢀ7.21 (m, 1H), 6.06 (dq, J = 15.6, 1.6 Hz, 1H), 5.64 (dq,
J = 16.0, 6.8 Hz, 1 H), 2.09 (s, 3H), 1.90 (s, 3H), 1.80 (dd, J = 6.8, 1.6 Hz,
3H); 1H NMR (400 MHz, C6D6) δ 7.40ꢀ7.46 (m, 2H), 7.14ꢀ7.21 (m,
2H), 7.02ꢀ7.08 (m, 1H), 6.15 (dq, J = 15.6, 1.6 Hz, 1H), 5.51 (dq, J =
15.6, 6.4 Hz, 1H), 2.02 (s, 3H), 1.85 (s, 3H), 1.63 (dd, J = 6.8, 1.2 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 207.0, 137.8, 129.2, 128.3, 126.4,
125.8, 124.5, 101.8, 99.6, 18.3, 17.1, 15.5; 13C NMR (101 MHz, C6D6) δ
207.5, 138.2, 129.9, 128.7, 126.9, 126.4, 124.5, 102.3, 100.4, 18.3, 17.3,
15.6; FTIR (νmax/cmꢀ1) 3029, 2981, 2911, 1933, 1598, 1491, 1444,
1367, 1065, 1026, 961, 757, 690, 603, 594; MS (EI, m/z) 184 (100, M+),
169 (98), 154 (86), 141 (70), 128 (51), 115 (36), 105 (19), 91 (30), 77
(15); HRMS (ESI) calcd for C14H17 (MH+) 185.1325, found 185.1324.
3ae. 1H NMR (400 MHz, CDCl3) δ 7.20ꢀ7.41 (m, 3H), 7.02ꢀ7.05
(m, 1H), 6.10 (dq, J = 15.2, 1.6 Hz, 1H), 5.67 (dq, J = 15.2, 6.4 Hz, 1H),
2.37 (s, 3H), 2.11 (s, 3H), 1.93 (s, 3H), 1.83 (dd, J = 6.8, 1.6 Hz, 3 H);
1H NMR (400 MHz, C6D6) δ 7.35 (s, 1H), 7.27ꢀ7.33 (m, 1H),
7.12ꢀ7.16 (m, 1H), 6.88ꢀ6.94 (m, 1H), 6.19 (dq, J = 15.6, 1.6 Hz, 1H),
5.50 (dq, J = 15.2, 6.4 Hz, 1H), 2.12 (s, 3H), 2.06 (s, 3H), 1.87
(s, 3H), 1.62 (dd, J = 6.8, 1.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
207.0, 138.79, 137.8, 129.4, 128.2, 127.3, 126.6, 124.3, 123.0, 101.6,
99.6, 21.6, 18.3, 17.3, 15.5; 13C NMR (100 MHz, C6D6) δ 207.5,
138.2, 138.0, 130.0, 128.7, 127.8, 127.1, 124.5, 123.6, 102.2, 100.4,
21.5, 18.4, 17.5, 15.7; FTIR (νmax/cmꢀ1) 3013, 2918, 2855, 1933,
1604, 1488, 1444, 1376, 1028, 962, 781, 696; MS (EI, m/z) 198 (100,
M+), 183 (87), 168 (78), 153 (47), 141 (37), 128 (32), 115 (34), 105
(17), 91 (32); HRMS (ESI) calcd for C15H19 (MH+) 199.1481, found
199.1481.
3ab. 1H NMR (400 MHz, CDCl3) δ 7.54 (d, JAB = 8.0 Hz, 2H), 7.44
(d, JAB = 8.0Hz, 2H), 6.05 (dq, J = 16.0, 2.0 Hz, 1H), 5.64 (dq, J = 15.6, 6.8
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3af. 1H NMR (400 MHz, CDCl3) δ 7.31ꢀ7.32 (m, 1H), 7.21ꢀ7.23
(m, 2H), 7.13ꢀ7.17 (m, 1H), 6.04 (dq, J = 15.6, 1.6 Hz, 1H), 5.67 (dq,
J = 15.6, 6.8 Hz, 1H), 2.07 (s, 3H), 1.89 (s, 3H), 1.81 (dd, J = 6.8, 1.6 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 207.3, 140.1, 134.4, 129.5, 128.9,
3aj. 1H NMR (400 MHz, C6D6) δ 7.06ꢀ7.14 (m, 1H), 6.77ꢀ6.84 (m,
1H), 6.66ꢀ6.75 (m, 1H), 6.04 (dq, J = 15.6, 1.6 Hz, 1H), 5.48 (dq, J = 15.6,
6.4 Hz, 1H), 1.80 (s, 3H), 1.76 (s, 3H), 1.61 (dd, J = 6.8, 1.6 Hz, 3H); 13C
NMR (101 MHz, C6D6) δ 207.0, 150.8 (dd, J = 236, 12.2 Hz), 149.6 (dd, J
= 246, 12.9 Hz), 135.6 (t, J = 5.0 Hz), 129.1, 125.4, 122.1 (dd, J = 6.1, 3.1
Hz), 117.2 (d, J = 16.8 Hz), 115.0 (d, J = 17.5 Hz), 18.1, 17.0, 15.2; FTIR
(νmax/cmꢀ1) 3037, 2986, 2928, 2859, 1933, 1735, 1603, 1515, 1445, 1289,
962, 817, 773; MS (EI, m/z) 220 (100, M+), 205 (82), 190 (56), 177 (55),
165 (43), 151 (33), 141 (29), 127 (21), 91 (22), 77 (6); HRMS (ESI)
calcd for C14H15F2 (MH+) 221.1136, found 221.1137.
126.5, 126.0, 125.3, 124.1, 102.5, 99.0, 18.5, 17.3, 15.6; FTIR (νmax
/
cmꢀ1) 3034, 2982, 2916, 2855, 1933, 1592, 1566, 1475, 1443, 1417,
1368, 1106, 1080, 1067, 1027, 961, 776, 748, 687, 609; MS (EI, m/z)
218 (97, M+), 203 (70), 183 (33), 175 (19), 168 (100), 153 (77), 141
(45), 128 (31), 115 (33), 102 (12), 91 (21), 77 (20); HRMS (ESI) calcd
for C14H16Cl (MH+) 219.0935, found 219.0936.
3ag. 1H NMR (400 MHz, CDCl3) δ 7.20ꢀ7.41 (m, 2H), 6.84ꢀ6.93
(m, 2H), 6.10 (dq, J = 15.6, 1.6 Hz, 1H), 5.54 (dq, J = 16.0, 6.8 Hz, 1H),
3.81 (s, 3H), 2.07 (s, 3H), 1.84 (s, 3H), 1.78 (dd, J = 6.4, 1.6 Hz, 3H); 1H
NMR (400 MHz, C6D6) δ 7.36 (dd, J = 7.6, 1.6 Hz, 1H), 7.06 (dt, J = 8.0,
1.2 Hz, 1H), 6.86 (t, J = 7.6 Hz, 1H), 6.56 (d, J = 8.4 Hz, 1H), 6.28 (dq, J
= 15.6, 1.6 Hz, 1H), 5.46 (dq, J = 15.6, 6.4 Hz, 1H), 3.33 (s, 3H), 2.22 (s,
3H), 1.88 (s, 3H), 1.64 (dd, J = 6.4, 1.6 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 207.5, 157.0, 130.1, 129.2, 128.1, 127.9, 123.4, 120.5, 111.4,
98.5, 97.2, 55.7, 19.6, 18.3, 15.7; 13C NMR (101 MHz, C6D6) δ 208.2,
157.6, 130.9, 129.9, 128.8, 127.9, 123.3, 120.9, 111.7, 99.1, 98.3, 55.2,
20.0, 18.4, 16.0; FTIR (νmax/cmꢀ1) 2924, 1596, 1578, 1491, 1434, 1245,
1029, 962, 749, 603; MS (EI, m/z) 214 (23, M+), 199 (100), 184 (38),
165 (34), 152 (25), 141 (25), 135 (78), 128 (29), 115 (34), 91 (30), 77
(28); HRMS (ESI) calcd for C15H19 (MH+) 215.1430, found 215.1430.
3ak. 1H NMR (400 MHz, C6D6) δ 8.88ꢀ8.92 (m, 1H), 8.42ꢀ8.47
(m, 1H), 7.34ꢀ7.37 (m, 1H), 6.70ꢀ7.38 (m, 1H), 6.04 (dq, J = 15.6, 1.2
Hz, 1H), 5.48 (dq, J = 15.6, 6.8 Hz, 1H), 1.86 (s, 3H), 1.76 (s, 3H), 1.6
(dd, J = 7.2, 1.2 Hz, 3H); 13C NMR (101 MHz, C6D6) δ 207.4, 148.3,
133.5, 132.6, 129.2, 125.3, 123.1, 103.0, 98.0, 18.3, 16.8, 15.4; FTIR
(νmax/cmꢀ1) 3037, 2985, 2924, 2858, 1932, 1569, 1479, 1445, 1417,
1378, 1020, 962, 806, 708, 605; MS (EI, m/z) 185 (68, M+), 170 (100),
154 (48), 142 (13), 128 (15), 115 (12), 106 (14), 91 (10), 77 (12);
HRMS (EI) calcd for C13H15N (M+) 185.1199, found 185.1199.
3al. 1H NMR (500 MHz, C6D6) δ 7.19ꢀ7.25 (m, 1H), 6.76ꢀ6.85
(m, 3H), 6.18 (d, J = 15.5 Hz, 1H), 5.46 (dq, J = 15.5, 6.5 Hz, 1H), 2.10
(s, 3H), 1.83 (s, 3H), 1.61 (d, J = 6.5 Hz, 3H); 13C NMR (126 MHz,
C6D6) δ 208.7, 160.5 (d, J = 248 Hz), 129.9, 129.6 (d, J = 3.8 Hz), 128.5
(d, J = 7.6 Hz), 128.4, 124.5, 124.2 (d, J = 3.8 Hz), 116. (d, J = 23.1 Hz),
100.5, 95.8, 19.4 (d, J = 2.0 Hz), 18.4, 15.7; FTIR (νmax/cmꢀ1) 3038,
2923, 2854, 1907, 1576, 1490, 1445, 1368, 1220, 1037, 961, 753, 601;
MS (EI, m/z) 202 (100, M+), 187 (74), 165 (57), 159 (52), 152 (50),
146 (44), 133 (35), 123 (35), 109 (30), 91 (14), 77 (9); HRMS (EI)
calcd for C14H15F (M+) 202.1152, found 202.1147.
3ah. 1H NMR (500 MHz, CDCl3) δ 7.78ꢀ7.87 (m, 2H), 7.70ꢀ7.77
(m, 2H), 7.54ꢀ7.59 (m, 1H), 7.40ꢀ7.52 (m, 2H), 6.14 (dq, J = 16.0, 1.0
Hz, 1H), 5.72 (dq, J = 15.5, 6.5 Hz, 1H), 2.25 (s, 3H), 1.97 (s, 3H), 1.85
(d, J = 5.5 Hz, 3H); 1H NMR (400 MHz, C6D6) δ 7.72ꢀ7.77 (m, 2H),
7.58ꢀ7.67 (m, 3H), 7.20ꢀ7.30 (m, 2H), 6.19 (dq, J = 15.6, 2.4 Hz, 1H),
5.54 (dq, J = 15.6, 6.8 Hz, 1H), 2.14 (s, 3H), 1.89 (s, 3H), 1.64 (dd, J = 6.4,
1.6 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ 208.0, 135.4, 133.8, 132.5,
129.3, 128.1, 127.71, 127.68, 126.2, 125.6, 125.5, 124.8, 123.5, 102.2,
100.1, 18.5, 17.4, 15.7; 13C NMR (101 MHz, C6D6) δ 208.3, 135.6, 134.4,
133.0, 129.7, 128.4, 128.2, 126.4, 125.9, 125.8, 124.8, 124.0, 102.6, 100.7,
18.4, 17.4, 15.7; FTIR (νmax/cmꢀ1) 3053, 2982, 2915, 1929, 1629, 1597,
1505, 1371, 1025, 961, 854, 817, 783, 745; MS (EI, m/z) 234 (100, M+),
219 (88), 204 (81), 189 (27), 178 (43), 165 (25), 152 (20), 141 (15);
HRMS (ESI) calcd for C18H19 (MH+) 235.1481, found 235.1481.
3am. 1H NMR (400 MHz, C6D6) δ 8.40ꢀ8.46 (m, 1H), 7.63ꢀ7.69
(m, 1H), 7.53ꢀ7.58 (m, 1H), 7.33ꢀ7.43 (m, 2H), 7.21ꢀ7.30 (m, 2H),
6.26 (dq, J = 15.6, 1.6 Hz, 1H), 5.43 (dq, J = 15.6, 6.8 Hz, 1H), 2.16 (s,
3H), 1.83 (s, 3H), 1.62 (dd, J = 6.8, 1.2 Hz, 3H); 13C NMR (101 MHz,
C6D6) δ 206.8, 138.0, 134.7, 131.8, 130.3, 128.9, 127.7, 126.2, 126.1,
126.0, 125.8, 125.5, 124.2, 99.6, 98.8, 21.7, 18.4, 15.9; FTIR (νmax
/
cmꢀ1) 3057, 2918, 2879, 2723, 1939, 1734, 1439, 1030, 960, 799, 775;
MS (EI, m/z, M+): 234 (26), 219 (100), 204 (63), 189 (32), 178 (16),
165 (26), 152 (14); HRMS (EI) calcd for C18H18 (M+), 234.1403,
found 234.1403.
3ai. 1H NMR (400 MHz, CDCl3) δ 7.20ꢀ7.23 (m, 1H), 7.01ꢀ7.05
(m, 2H), 6.27 (dq, J = 15.6, 1.6 Hz, 1H), 5.96 (dq, J = 15.6, 6.4 Hz, 1H),
2.06 (s, 3H), 1.87 (s, 3H), 1.79 (dd, J = 6.8, 1.2 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 206.8, 140.1, 129.3, 126.9, 125.2, 124.5, 118.7, 103.3,
99.1, 18.3, 17.7, 15.6; FTIR (νmax/cmꢀ1) 3103, 2987, 2922, 2855, 1929,
1442, 1368, 1247, 1183, 1026, 962, 864, 775, 644; MS (EI, m/z) 190 (95,
M+), 175 (100), 160 (45), 147 (32), 142 (59), 134 (23), 129 (17), 115
(25); HRMS (ESI) calcd for C12H15S (MH+) 191.0889, found 191.0889.
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3an. 1H NMR (400 MHz, C6D6) δ 6.08ꢀ6.23 (m, 2H), 5.53 (dt, J =
15.6, 6.8 Hz, 1H), 5.45 (dq, J = 15.6, 6.4 Hz, 1H), 2.00 (q, J = 7.2 Hz,
2H), 1.85 (s, 3H), 1.82 (s, 3H), 1.62 (dd, J = 6.8, 1.6 Hz, 3H), 1.33 (sext,
J = 7.6 Hz, 2H), 0.84 (t, J = 7.2 Hz, 3H); 13C NMR (101 MHz, C6D6) δ
209.5, 130.5, 129.5, 129.2, 123.8, 99.79, 99.75, 35.4, 23.1, 18.3, 16.1, 16.0,
13.9; FTIR (νmax/cmꢀ1) 3037, 2959, 2927, 2872, 1929, 1439, 1377,
1032, 961, 586; MS (EI, m/z, M+): 176 (51), 161 (14), 147 (42), 133
(31), 119 (100), 105 (75), 91 (59), 77 (25); HRMS (EI) calcd for
C13H20 (M+) 176.1560, found 176.1552.
3ea. 1H NMR (400 MHz, C6D6) δ 7.50ꢀ7.57 (m, 4H),
7.12ꢀ7.20 (m, 4H), 7.02ꢀ7.09 (m, 2H), 6.27 (dq, J = 15.6, 2.0
Hz, 1H), 5.96 (dq, J = 15.6, 6.8 Hz, 1H), 2.47 (t, J = 7.6 Hz, 1H), 2.46
(t, J = 7.6 Hz, 1H), 1.62 (dd, J = 6.8, 1.6 Hz, 3H), 1.54ꢀ1.65 (m,
2H), 1.31 (sext, J = 15.6, 2H), 0.82 (t, J = 15.6 Hz, 3H); 13C NMR
(101 MHz, C6D6) δ 207.7, 137.3, 137.1, 128.9, 128.8, 128.7, 127.9,
127.4, 127.2, 127.0, 126.5, 111.3, 109.1, 30.6, 30.5, 23.0, 18.5, 14.2;
FTIR (νmax/cmꢀ1) 3026, 2956, 2929, 2858, 1597, 1492, 1445, 960,
756, 692; MS (EI, m/z) 288 (8, M+), 259 (19), 246 (168), 231 (100),
215 (77), 202 (28), 165 (16), 155 (20), 128 (21), 115 (28), 91 (26),
77 (13); HRMS (EI) calcd for C22H24 (M+) 288.1873, found
288.1876.
3ba. 1H NMR (400 MHz, CDCl3) δ 7.37ꢀ7.41 (m, 2H), 7.28ꢀ7.34
(m, 2 H), 7.17ꢀ7.23 (m, 1H), 6.10 (dq, J = 15.6, 1.6 Hz, 1H), 5.67 (dq,
J = 15.6, 6.6 Hz, 1H), 2.47 (t, J = 7.6 Hz, 2H), 1.93 (s, 3H), 1.83 (dd, J =
6.6, 2.0 Hz, 3H), 1.53 (quint, J = 7.2 Hz, 2H), 1.44 (sext, J = 7.6 Hz, 2H),
0.95 (t, J = 7.4 Hz, 3H); 1H NMR (400 MHz, C6D6) δ 7.45ꢀ7.49 (m,
2H), 7.15ꢀ7.22 (m, 2H), 7.03ꢀ7.10 (m, 1H), 6.19 (dq, J = 15.6, 1.6 Hz,
1H), 5.67 (dq, J = 15.6, 6.6 Hz, 1H), 2.42 (t, J = 7.6 Hz, 2H), 1.87 (s,
3H), 1.64 (dd, J = 6.8, 1.6 Hz, 3H), 1.56 (quint, J = 7.6 Hz, 2H), 1.36
(sext, J = 7.6 Hz, 2H), 0.87 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 207.0, 137.8, 129.6, 128.4, 126.5, 126.3, 124.4, 105.1, 103.2,
30.3, 30.2, 22.6, 18.5, 15.7, 14.1; 13C NMR (101 MHz, C6D6) δ 207.3,
138.0, 129.9, 128.7, 126.9, 126.7, 124.4, 105.7, 105.6, 30.6, 30.5, 22.9,
18.4, 15.7, 14.2; FTIR (νmax/cmꢀ1) 3025, 2957, 2928, 2859, 1931, 1599,
1492, 1446, 1376, 961, 757, 693; MS (EI, m/z) 226 (13, M+), 211 (7),
197 (13), 184 (50), 169 (100), 155 (37), 141 (31), 128 (23), 115 (21),
91 (25), 77 (8); HRMS (EI) calcd for C17H22 (M+) 226.1716, found
226.1712.
3fa. 1H NMR (400 MHz, CDCl3) δ 7.37ꢀ7.43 (m, 2H),
7.31ꢀ7.36 (m, 2H), 7.21ꢀ7.24 (m, 1H), 6.08 (dt, J = 19.6, 1.6
Hz, 1H), 5.66 (dt, J = 15.6, 7.2 Hz, 1H), 2.13ꢀ2.20 (m, 2H), 2.13 (s,
3H), 1.93 (s, 3H), 1.32ꢀ1.48 (m, 4H), 0.94 (t, J = 7.6 Hz, 3H); 1H
NMR (500 MHz, C6D6) δ 7.40ꢀ7.46 (m, 2H), 7.12ꢀ7.20 (m, 2H),
7.00ꢀ7.09 (m, 1H), 6.20 (dt, J = 15.5, 1.5 Hz, 1H), 5.60 (dt, J = 12.5,
6.0 Hz, 1H), 2.00ꢀ2.10 (m, 2H), 2.03 (d, J = 3.0 Hz, 3H), 1.89 (d, J =
3.0, 3H), 1.20ꢀ1.22 (m, 4H), 0.84 (t, J = 7.5 Hz, 3H); 13C NMR
(101 MHz, CDCl3) δ 207.2, 137.8, 130.08, 128.3, 127.9, 126.4,
125.9, 101.9, 99.6, 32.7, 31.8, 22.3, 17.1, 15.5, 14.0; 13C NMR (126
MHz, C6D6) δ 207.7, 138.2, 130.2, 128.7, 128.6, 126.9, 126.4, 102.4,
100.4, 33.1, 32.1, 22.7, 17.3, 15.7, 14.2; FTIR (νmax/cmꢀ1) 3027,
2956, 2925, 2863, 1933, 1492, 1444, 1367, 1027, 963, 758, 692, 604,
596; MS (EI, m/z) 226 (38, M+), 211 (21), 197 (9), 183 (100), 168
(52), 155 (83), 141 (55), 128 (40), 115 (37), 105 (28), 91 (33), 77
(21); HRMS (ESI) calcd for C17H23 (MH+) 227.1794, found
227.1795.
3ca. 1H NMR (400 MHz, C6D6) δ 7.44ꢀ7.57 (m, 2H), 7.17ꢀ7.21
(m, 2H), 7.02ꢀ7.09 (m, 1H), 6.19 (dq, J = 15.6, 1.6 Hz, 1H), 5.54 (dq, J =
15.6, 6.8 Hz, 1H), 2.44ꢀ2.52 (m, 1H), 1.95ꢀ2.03 (m, 2H), 1.87 (s, 3H),
1.65 (dd, J = 6.8, 1.6 Hz, 3H), 1.59ꢀ1.73 (m, 3H), 1.24ꢀ1.32 (m, 4H),
1.11ꢀ1.19 (m, 1H); 13C NMR (101 MHz, C6D6) δ 207.1, 137.8, 130.2,
128.7, 127.2, 126.8, 124.2, 112.2, 104.3, 38.6, 33.3, 33.5, 27.0, 26.8, 18.4,
15.9; FTIR (νmax/cmꢀ1) 3021, 2924, 2851, 1928, 1598, 1493, 1446, 961,
764, 693; MS (EI, m/z) 252 (18, M+), 237 (18), 223 (31), 195 (26), 183
(100), 169 (50), 155 (48), 141(30), 128 (29), 115(25), 91(36), 77 (12);
HRMS (EI) calcd for C19H24 (M+) 252.1873, found 252.1871.
3ga. 1H NMR (400 MHz, C6D6) δ 7.32ꢀ7.50 (m, 2H),
7.10ꢀ7.20 (m, 2H), 7.00ꢀ7.08 (m, 1H), 6.20 (dd, J = 15.8, 1.4
Hz, 1H), 5.59 (dd, J = 15.6, 7.0 Hz, 1H), 2.21ꢀ2.32 (m, 1H), 2.03 (s,
3H), 1.89 (s, 3H), 0.956 (d, J = 7.2 Hz, 3H), 0.953 (d, J = 7.2 Hz,
3H); 13C NMR (101 MHz, C6D6) δ 207.9, 138.2, 137.0, 128.7,
126.9, 126.4, 125.9, 102.3, 100.4, 31.9, 22.7, 17.3, 15.7; FTIR (νmax
/
cmꢀ1) 3027, 2958, 2867, 1933, 1597, 1492, 1465, 1444, 1366, 1066,
1029, 964, 758, 692, 603; MS (EI, m/z) 212 (47, M+), 197 (100),
182 (32), 169 (31), 165 (29), 155 (48), 141 (36), 128 (35), 115 (29),
91 (24), 77 (15); HRMS (EI) calcd for C16H20 (M+) 212.1560,
found 212.1551.
3da. 1H NMR (400 MHz, C6D6) δ 7.46ꢀ7.53 (m, 2H), 7.16ꢀ7.23
(m, 2H), 7.03ꢀ7.09 (m, 1H), 6.14 (dd, J = 15.7, 1.6 Hz, 1H), 5.65 (dq, J
= 15.7, 6.7 Hz, 1H), 2.46 (t, J = 8.0 Hz, 2H), 2.26 (t, J = 7.6 Hz, 2H), 1.66
(dd, J = 6.8, 1.5 Hz, 3H), 1.54ꢀ1.64 (m, 4H), 1.30ꢀ1.41 (m, 4H), 0.88
(t, J = 7.2 Hz, 3H), 0.85 (t, J = 7.2 Hz, 3H); 13C NMR (101 MHz, C6D6)
δ 206.8, 138.0, 129.4, 128.7, 126.9, 126.5, 124.1, 108.7, 107.3, 30.8,
30.61, 30.60, 29.6, 23.2, 23.0, 18.6, 14.3, 14.2; FTIR (νmax/cmꢀ1) 3023,
2956, 2927, 2858, 1597, 1493, 1448, 1377, 961, 757, 692; MS (EI, m/z)
268 (2, M+), 239 (4), 226 (3), 211 (39), 183 (33), 169 (100), 155 (38),
141 (48), 128 (14), 115 (17), 91 (28), 77 (8); HRMS (EI) calcd for
C20H28 (M+) 242.1485, found 242.1485.
3ha. 1H NMR (500 MHz, C6D6) δ 7.46ꢀ7.50 (m, 4H),
7.14ꢀ7.23 (m, 4H), 7.05ꢀ7.10 (m, 2H), 6.16 (dq, J = 15.5, 1.5
Hz, 1H), 5.50 (dq, J = 15.8, 6.5 Hz, 1H), 1.84 (s, 3H), 1.61 (dd, J =
7.0, 1.5 Hz, 3H); 13C NMR (126 MHz, C6D6) δ 209.5, 137.9, 129.2,
129.1, 128.8, 127.4, 125.4, 110.2, 103.5, 18.4, 15.6; FTIR (νmax
/
cmꢀ1) 3029, 2925, 1715, 1598, 1492, 1445, 962, 900, 839, 768,
738, 695, 630; MS (EI, m/z) 246 (100, M+), 231 (24), 215 (70),
202 (27), 189 (12), 165 (17), 153 (21), 128 (10), 115 (14), 91 (9),
77 (8); HRMS (EI) calcd for C19H18 (M+) 246.14030, found
246.13960.
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The Journal of Organic Chemistry
ARTICLE
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: leventartok@iyte.edu.tr.
1
3ia. H NMR (400 MHz, C6D6) δ 7.30ꢀ7.35 (m, 2H), 7.11ꢀ
7.17 (m, 2H), 7.04ꢀ7.10 (m, 1H), 6.22 (dq, J = 15.6, 1.6 Hz, 1H), 5.42
(dq, J = 6.8, 15.6 Hz, 1H), 1.79 (s, 3H), 1.64 (dd, J = 6.4, 1.6 Hz, 3H),
1.20 (s, 9H); 13C NMR (101 MHz, C6D6) δ 204.7, 138.6, 130.8, 129.9,
128.2, 126.8, 123.6, 115.6, 101.0, 35.4, 30.3, 18.4, 16.2; FTIR
(νmax/cmꢀ1) 3018, 2965, 2902, 2866, 1442, 1361, 960, 755, 737, 698,
570; MS (EI, m/z) 226 (7, M+), 196 (6), 181 (6), 169 (100), 154 (72),
141 (25), 128 (24), 115 (19), 91 (26), 77 (12); HRMS (EI) calcd for
C17H22 (M+) 226.1716, found 226.1710.
’ ACKNOWLEDGMENT
The financial support of The Scientific and Technological
Research Council of Turkey and Federal Ministry of Education
and Research (Germany) via the Intensified Cooperation Pro-
gram (210T092), a Fellowship Program by Deutscher Akade-
mischer Austauschdienst, and a Scientific Exchange Fellowship
Program by The Scientific and Technological Research Council
of Turkey and Deutsche Forschungs Gemeinschaft to L.A. are
€
gratefully acknowledged. We thank Ms. I. Ozcelik, Mr. S.
)
€
G€unnaz, and Dr. W. Hiller for NMR analyses, Dr. H. Ozgener
for FTIR analyses, and Dr. R. Eanes for proofreading.
1
3ja. H NMR (400 MHz, C6D6) δ 7.24ꢀ7.28 (m, 2H), 7.08ꢀ
’ REFERENCES
7.15 (m, 2H), 6.90ꢀ7.04 (m, 1H), 6.23 (s, 1H), 6.12 (d, J = 15.6 Hz,
1H), 5.50 (dq, J = 15.6, 6.4 Hz, 1H), 1.82 (d, J = 2.8 Hz, 3H), 1.60 (d, J =
6.4 Hz, 3H); 13C NMR (101 MHz, C6D6) δ 208.7, 135.6, 129.1, 128.9,
127.3, 127.1, 125.2, 104.2, 99.7, 18.3, 15.5; FTIR (νmax/cmꢀ1) 3024,
2871, 1932, 1598, 1495, 1448, 960, 825, 742, 692, 631; MS (EI,
m/z) 170 (75, M+), 155 (100), 141 (24), 128 (45), 115 (36), 102
(8), 91 (28), 77 (20); HRMS (EI) calcd for C13H14 (M+), 170.1090,
found 170.1084.
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3la. 1H NMR (400 MHz, CDCl3) δ 7.42ꢀ7.36 (m, 2H), 7.35ꢀ7.28
(m, 2H), 7.22ꢀ7.16 (m, 1H), 6.15 (dt, J = 10.0, 2.8 Hz, 1H), 5.92 (ddq,
JAB = 15.2, 10.4, 1.2 Hz, 1H), 5.74 (dq, JAB = 15.2, 6.8 Hz, 1H),
2.49ꢀ2.41 (m, 2H), 1.77 (dd, J = 6.0, 1.2 Hz, 2H), 13C NMR (100 MHz,
CDCl3) δ 207.0, 137.0, 128.5, 127.9, 126.8, 126.7, 126.3, 107.1, 97.3,
30.2, 30.0, 22.6, 18.4, 14.1; FTIR (νmax/cmꢀ1) 2956, 2926, 2857, 1931,
1492, 1447, 1026, 962, 758, 692; MS (EI, m/z) 212 (5, M+), 170 (48),
155 (100), 141 (28), 128 (19), 115 (20), 91 (21), 77 (6); HRMS (EI)
calcd for C16H20 (M+) 212.1560, found 212.1554.
3ma. 1H NMR (400 MHz, C6D6) δ 7.39ꢀ7.45 (m, 2H),
7.15ꢀ7.21 (m, 2H), 7.02ꢀ7.09 (m, 1H), 6.51 (dd, J = 17.2, 10.4
Hz, 1H), 5.12 (dd, J = 17.2, 1.2 Hz, 1H), 4.99 (dd, J = 10.8, 0.8 Hz,
1H), 2.39 (t, J = 7.6 Hz, 2H), 1.84 (s, 3H), 1.51 (quint, J = 7.6 Hz,
2H), 1.33 (sext, J = 7.6 Hz, 2H), 0.86 (t, J = 7.6 Hz, 3H); 13C NMR
(101 MHz, C6D6) δ 208.3, 137.5, 136.1, 128.8, 127.0, 126.7, 112.9,
106.0, 103.9, 30.4, 30.3, 22.8, 14.9, 14.2; FTIR (νmax/cmꢀ1) 3026,
2957, 2929, 2859, 1931, 1613, 1493, 1455, 896, 759, 739, 694; MS
(EI, m/z, M+): 212 (2, M+), 197 (1), 170 (54), 155 (100), 141 (35),
128 (23), 115 (31), 91 (23), 77 (12); HRMS (EI) calcd for C16H20
(M+) 212.1560, found 212.1560.
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’ ASSOCIATED CONTENT
S
Supporting Information. Calculated DFT parameters
b
and 1H and 13C spectra of all products. This material is available
free of charge via the Internet at http://pubs.acs.org.
5970
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The Journal of Organic Chemistry
(13) Akpınar, G. E.; Kus, M.; Uc€unc€u, M.; Karakus, E.; Artok, L. Org.
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dx.doi.org/10.1021/jo200201r |J. Org. Chem. 2011, 76, 5959–5971