Aminocarbonylations of alkenyl phosphates, chlorides, bromides, and triflates with Mo(CO)6 as a solid CO source

Article abstract of DOI:10.1016/j.tet.2009.06.101

Palladium-catalyzed aminocarbonylations of alkenyl chlorides, bromides, and triflates were investigated using Mo(CO)₆ as a solid carbon monoxide source. The reactions afforded moderate to good yields producing a wide variety of acrylamides afte

Full text of DOI:10.1016/j.tet.2009.06.101

Tetrahedron 65 (2009) 7646–7652
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Aminocarbonylations of alkenyl phosphates, chlorides, bromides, and triflates
with Mo(CO)6 as a solid CO source
*
Olof Lagerlund, Mette L.H. Mantel, Mats Larhed
Organic Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala Biomedical Center, Uppsala University, PO Box 574, SE-751 23 Uppsala, Sweden
a r t i c l e i n f o
a b s t r a c t
Article history:
Palladium-catalyzed aminocarbonylations of alkenyl chlorides, bromides, and triflates were investigated
using Mo(CO)6 as a solid carbon monoxide source. The reactions afforded moderate to good yields
producing a wide variety of acrylamides after 20 min of microwave irradiation. In addition, the ami-
nocarbonylation reaction was, for the first time, expanded to include alkenyl phosphates as starting
materials.
Received 24 March 2009
Received in revised form 9 June 2009
Accepted 25 June 2009
Available online 2 July 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Carbonylation
Microwave
Vinyl halides
Vinyl phosphates
Vinyl triflates
Alkenyl electrophiles
Palladium
Enolizable ketones
1. Introduction
[Pd], ligand
R
R
Mo(CO)6
NR1R2
+
HNR1R2
2a-f
X
Palladium(0)-catalyzed carbonylations with aryl and alkenyl
halides were first reported by Heck et al., in the early seventies.1,2
The scope of this reaction has increased dramatically and today
a wide variety of carboxylic acid derivates can readily be syn-
thesized by using different nucleophiles.3–5 A drawback for many
protocols is the use of toxic carbon monoxide gas and the need for
high-pressure reaction conditions. In recent years different
methodologies have been developed to overcome the handling of
gaseous CO,6 such as the use of formamide7,8 or metal carbonyls as
CO in situ sources,9,10 thus making it easier and safer to perform
carbonylative transformations in a small-scale synthetic labora-
tory. We have previously reported a number of standard methods
for the carbonylation of aryl halides and halide surrogates, using
Mo(CO)6 as a CO releasing solid reagent.9–17 Advantages of using
Mo(CO)6 as a replacement for gaseous CO include the fact that it is
easily manipulated and can be conveniently used on a small scale
(Scheme 1).18
DBU, THF
1a-k
O
MW, rt-190 °C
3a-x
2a
Benzylamine
X = OPO(OR3)2
2b
2c
2d
2e
2f
Hexylamine
Aniline
Cl
Br
Pyrrolidine
OTf
3-Phenylpropylamine
Tryptamine
Scheme 1. Synthesis of acrylamides from different alkenyl electrophiles.
combination with the use of sealed reaction vials, this heating
technology holds several advantages such as increased reaction
rates and a larger array of controllable reaction parameters.19
Numerous conditions and methodologies have been developed
for the aminocarbonylation of aryl halides and halide surrogates
over the years.4,20,21 However, alkenyl substrates have not been
investigated to the same extent under CO-free conditions or with
microwave heating.
Alkenyl iodides, triflates, and bromides have been used as ef-
fective reactants in carbonylative transformations utilizing CO
gas.22–25 There are a few examples with alkenyl chlorides,2,26 but
until now, no gas-free aminocarbonylations with alkenyl triflates,
bromides or chlorides have been published. Alkenyl phosphates
have not previously been used in aminocarbonylation chemistry,
The use of high-density microwave heating in organic synthesis
has increased since the arrival of dedicated microwave reactors. In
* Corresponding author. Tel.: þ46 18 471 46 67; fax: þ46 18 47 44 74.
E-mail address: Mats.Larhed@orgfarm.uu.se (M. Larhed).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.06.101

O. Lagerlund et al. / Tetrahedron 65 (2009) 7646–7652
7647
although
a
single alkoxycarbonylation has been published.27
Table 1
Aminocarbonylation of alkenyl phosphates and halides
Alkenyl phosphates have, however, proven useful as substrates in
Heck,28,29 Suzuki,30 Stille,31 and Negishi32 reactions. These alke-
nylpalladium precursors are obtained in a straightforward manner
from the corresponding ketones using LiHMDS and diphenyl or
diethyl chlorophosphate.28,33,34 We herein report a series of mi-
crowave assisted palladium catalyzed aminocarbonylation pro-
tocols utilizing Mo(CO)6 as the solid CO source. Furthermore, we
will show that alkenyl phosphates and their corresponding chlo-
ride, bromide, and triflate counterparts can successfully be applied
as coupling partners in this transformation.
Entry
Vinyl
Amine
Product
Temp Isolated
(ꢀC)
yield (%)
O
O
P
O
O
Ph
1
1a 2a
3a 170
75
O
N
H
Ph
O
2
1a 2b
3b 170
47
N
H
170
50a
O
3
4
1a 2c
1a 2e
3c 170
3d 170
42
47
2. Results and discussion
N
H
O
O
2.1. Alkenyl phosphates as coupling partners
N
H
Utilizing modified conditions previously developed in our group
for the carbonylation of aryl chlorides,17 a microwave vial charged
with 0.5 mmol of 3,3-dimethyl-1-buten-2-yl O,O-diphenyl phos-
NH
5
6
1a 2f
1b 2a
3e 170
35
62
N
H
phate (1a), benzylamine (2a) (3 equiv), Mo(CO)6 (0.5 equiv), Herr-
mann’s palladacycle35 (0.025 equiv), HP(t-Bu)3BF4
(0.05
36
equiv), DBU (3 equiv) and THF (2 mL) was heated using microwaves
for 20 min at 170 ꢀC. The product 3a was isolated in a 75% yield
(entry 1, Table 1). Attempts to increase the yield by varying reaction
time and temperature did not result in any improvements. We
decided to further investigate the scope and limitations of this
protocol (Table 1). When exchanging 2a with 2b, the isolated yield
of 3b was only 47%, despite full conversion of 2b according to GC–
MS. Doubling the reaction scale from 0.5 to 1.0 mmol afforded
a slight increase in yield (50%) (entry 2, Table 1). Other amines
tested with tert-butyl alkenyl phosphate (1a) afforded similar
yields as with 2b (entries 3–5, Table 1). Adamantyl alkenyl phos-
phate (1b) and tert-butylcyclohexenyl phosphates (1c,d) furnished
yields varying from 20% to 66% (entries 6–13, Table 1).
Secondary amines generally afforded low yields in combination
with alkenyl phosphates, here exemplified by pyrrolidine (2d)
(entry 9, Table 1). No general trend could be identified for the
primary amines, except for aniline which afforded lower yields in
most cases. Full consumption of the naphthyl phosphate (1e) re-
quired an increase in temperature to 190 ꢀC, which in turn resulted
in low isolated yields (entries 14 and 15, Table 1). The poor result
was, in part, due to the formation of an enamine by-product.37–39 In
an attempt to make the carbonylation process more efficient, we
decided to decrease the amount of amine and increase the amount
of the Mo(CO)6. Lowering the amount of amine did not significantly
influence the reaction outcome. However, enamine formation was
suppressed when the amount of Mo(CO)6 was increased to 2 equiv.
Despite the suppressed enamine formation, a lower yield of ac-
rylamide 3n was obtained (10% vs 33%) (entry 15, Table 1). Finally,
a comparison between the ethyl (1c) and phenyl (1d) phosphate
ester leaving groups were made. Both phosphate groups performed
equally well, producing 3k in 62% and 66% yield, respectively (en-
tries 11 and 13, Table 1).
O
P
O
O
O
Ph
Ph
3f
170
O
N
H
O
7
1b 2b
1b 2c
1b 2d
1c 2a
3g 170
3h 170
51
N
H
O
8
20b
27
42
N
H
O
9
3i
3j
170
170
N
Et
O
O
O
O
P
O
Et
N
10
H
O
N
H
11
12
1c 2b
1c 2c
3k 170
62
43
O
N
H
3l
170
Ph
O
O
O
O
P
O
Ph
N
H
13
1d 2b
3k 170
3m 190
66
38
O
P
O
O
Ph
O
Ph
O
14
15
1e 2a
1e 2b
N
H
2.2. Alkenyl halides as coupling partners
O
3n 190
33
N
H
10c
The reaction between 1-chloro-1-cyclopentene (1f) and benzyl
amine (2a) was chosen as a model reaction for a series of optimi-
zation experiments (entry 16, Table 1). Under the conditions de-
veloped for alkenyl phosphates, full consumption of the starting
material (1f) was achieved after 20 min at 170 ꢀC, but isolated
yields of 3o did not exceed 50%. Varying the reaction time and
temperature or adding the acyl transfer reagent 4-dimethylamino-
pyridine (DMAP)11 did not result in any improvement. Applying the
biaryl monophosphine ligand Xphos,40,41 which has previously
been used in aminocarbonylations with aryl triflates,11 completely
190
O
Cl
16
17
1f 2a
3o 170
61
N
H
47d
O
1f 2b
3p 170
61
N
H
(continued on next page)

7648
O. Lagerlund et al. / Tetrahedron 65 (2009) 7646–7652
Table 1 (continued )
Table 2
Aminocarbonylation of alkenyl triflates
Entry
Vinyl
Amine
Product
Temp Isolated
(ꢀC)
yield (%)
Entry
Vinyl-X
Amine
Product
Temp Isolated
(ꢀC) yield (%)
O
Br
N
H
18
1g 2a
3q 140
64
O
O
O
OTf
1
1i
1i
1i
1i
2a
3t
rta
69a
N
H
60 67
O
60b 73b
N
H
19
20
1g 2b
3r 140
72
73
O
O
2
3
4
2b
2c
2d
3u
3v
60
80
62
78
73
N
H
O
Br
1h 2a
3s 140
N
H
O
O
N
H
Conditions: 0.5 mmol alkenyl halide or phosphate, amine (3 equiv), Mo(CO)6
(0.5 equiv), Herrmann’s palladacylcle (0.025 equiv), HP(t-Bu)3BF4 (0.05 equiv), DBU
(3 equiv), THF (2 mL), sealed vial, 20 min microwave irradiation. 95% purity on NMR.
O
O
a
1 mmol scale.
3w 80
b
N
90% purity on NMR.
2 equiv Mo(CO)6.
c
d
2 mmol scale.
O
OTf
N
H
5
6
7
1j
1j
1j
2a
2b
2c
3j
60
60
60
54
51
55
inhibited the catalytic process and provided no product. Returning
to the original conditions from the alkenyl phosphates, but at an
increased scale of 2 mmol, the product 3o was afforded in a 61%
yield (entry 16, Table 1).
O
N
H
3k
3l
Although 1f performed well with hexylamine (2b) (entry 17,
Table 1), it failed to provide useful yields with the studied secondary
amines (dibutylamine and dibenzylamine). 1-Chloro-2-methyl-1-
propene was also examined, but the yields were low even with the
otherwise effective primary amines 2a and 2b (untabulated results).
The established reaction protocol also proved suitable applying
alkenyl bromides. In this case, the temperature could be lowered to
O
N
H
O
140 ꢀC. The reaction between
b-bromostyrene (1 g) and 2a resulted
OTf
8
1k
2a
3x
60
45
N
H
in full conversion and a good isolated yield of 3q (64%, entry 18, Table
1). A few more experiments were made to show the applicability of
the protocol and good yields were obtained with both the styrene 1g
and bromomethylenecyclohexane (1h) (entries 19 and 20, Table 1).
Conditions: 0.5 mmol alkenyl triflate, amine (3 equiv), Mo(CO)6 (0.5 equiv),
Pd(OAc)2 (0.025 equiv), Xphos (0.075 equiv), DBU (3 equiv), THF (2 mL), N2 atmo-
sphere, sealed vial, 20 min at 60–80 ꢀC, microwave irradiation. 95% purity on NMR.
a
Over-night, no microwave irradiation.
b
Without Xphos.
2.3. Alkenyl triflates as coupling partners
3. Conclusion
To increase the scope of the reaction, we decided to investigate
vinyl triflates as coupling partners. The reaction between
6-methoxy-3,4-dihydronaphthalen-1-yl triflate (1i) and benzyl-
amine (2a) was selected as a suitable test reaction (entry 1, Table 2).
Employing Xphos as the ligand instead of HP(t-Bu)3BF4 improved
the reaction outcome during our initial screening. The reaction
proceeded at only 60 ꢀC, allowing the use of less expensive
Pd(OAc)2 as the palladium source. Furthermore, this reaction could
also be carried out over-night at room temperature or without
a phosphine ligand. However, reactions with other amines were
considerably less efficient under ligand-less conditions.
The first method for aminocarbonylation of alkenyl phosphates
was developed as well as protocols for CO-free aminocarbonylation
of vinyl chlorides, bromides, and triflates. Two different palladium
based catalytic systems were used in conjunction with Mo(CO)6 as
a solid CO source. Microwave irradiation furnished modest to good
yields of various acrylamides after only 20 min of heating.
4. Experimental
During the course of the optimization, benzyl formamide was
detected as a by-product in most reactions. The formation of
4.1. General information and materials
formamide is believed to proceed through
a
carbamoyl in-
All syntheses were carried out in a Smith/EmrysÔ Synthesizer
single-mode microwave cavity producing controlled irradiation at
2450 MHz (Biotage AB, Uppsala, Sweden). GC–MS analyses were
performed on a Varian 3900 or 3800, equipped with a CP-SIL 8 CB
Low Bleed (30 mꢁ0.25 mm) respectively CP-SIL 5 CB Low Bleed
(30 mꢁ0.25 mm) capillary column using a 40–300 ꢀC temperature
gradient and EI ionization. RP-LC–MS analyses were performed
using a Gilson HPLC system with a Chromolith SpeedROD RP-18e
column (50ꢁ4.6 mm) and a Finnigan AQA quadropole mass spec-
trometer using a 4 mL/min CH3CN/H2O gradient (0.05% HCOOH)
and detection by UV (DAD) and MS (ESIþ). 1H and 13C NMR spectra
were recorded on a Varian Mercury-400 spectrometer at 400 and
100.5 MHz, respectively. Chemical shifts for 1H and 13C are
termediate, via a palladium(II)-catalyzed pathway.42,43 To avoid the
formation of catalytically active Pd(II), all the following reactions
were performed under a nitrogen atmosphere. The formamide was
not detected during the investigations of the alkenyl halides or
phosphates, possibly due to the breakdown of formamide at high
temperatures.7,44 The results of the developed Xphos/Pd(OAc)2
protocol using the alkenyl triflates (1i–k) and the amines 2a–d are
depicted in Table 2. In all entries modest to good isolated yields
(45–78%) were obtained after 20 min of microwave irradiation.
Interestingly, the use of pyrrolidine furnished a 73% yield of product
3w, a result in sharp contrast to the poor results experienced with
secondary amines and alkenyl phosphates (entry 9, Table 1).

O. Lagerlund et al. / Tetrahedron 65 (2009) 7646–7652
7649
referenced to TMS via the solvent signal. IR spectra were recorded
on a Varian 1000 FT-IR and melting points were recorded using an
electrothermal melting point apparatus.
Column chromatography was performed using Merck Silica gel
60 (0.040–0.063 mm). THF was freshly distilled over Na/benzo-
phenone. All products were >95% pure according to NMR unless
otherwise stated.
Eluent for chromatography: CH2Cl2:diethylether (80:20).
1H NMR (400 MHz, CDCl3):
7.36–7.28 (m, 5H), 5.87 (br s, 1H),
d
5.23 (s, 1H), 5.20 (s, 1H), 4.48 (d, J¼5.6 Hz, 2H), 1.21 (s, 9H).
13C NMR (100 MHz, CDCl3):
127.6, 113.0, 43.5, 35.2, 29.4.
d 171.2, 156.6, 138.6, 128.8, 127.8,
HRMS: Calculated, 218.1545. Found, 218.1541.
IR (neat): v 1646, 1619, 1527 cmꢂ1. Mp: 42–44 ꢀC.
Materials: All chemicals used were commercially available ex-
cept compounds 1i–1k, which were available in house and 1b,
which was a gift from Troels Skrydstrups group at Aarhus Univer-
sity, Denmark. Compounds 1a and 1c–1e were prepared according
to literature procedures28 by proton extraction and subsequent
treatment with diphenyl- or diethyl chlorophosphate.
4.5.2. N-Hexyl-3,3-dimethyl-2-methylenebutanamide (3b)
Following the general procedure A, 3b was prepared in a 47%
yield as a colourless oil.
Eluent for chromatography: CH2Cl2:diethylether (95:5).
1H NMR (400 MHz, CDCl3):
d 5.60 (br s, 1H), 5.16 (s, 1H), 5.15 (s,
1H), 3.26 (dt, J¼7.2, 6.0 Hz, 2H), 1.54–1.47 (m, 2H), 1.34–1.26 (m,
4.2. Procedure and characterization of the new compound 1d
6H), 1.18 (s, 9H), 0.87 (t, J¼6.8 Hz, 3H).
13C NMR (100 MHz, CDCl3):
29.7, 29.5, 26.7, 22.7, 14.1.
d 171.5, 157.1, 112.4, 39.5, 35.2, 31.6,
4.2.1. O,O-Diphenyl 4-tert-butylcyclohex-1-enylphosphonate (1d)
4-tert-Butylcyclohexanone (0.77 g, 5 mmol) was dissolved in
THF (5 mL) and then added to 1 M LiHMDS (6.5 mL) in THF at ꢂ78 ꢀC
and stirred for 25 min. Diphenyl chlorophosphate (2.01 g,
7.5 mmol) was dissolved in THF (5 mL) and then added to the re-
action mixture. The reaction was allowed to warm to room tem-
perature under continuous stirring. After 2 h, diethylether (25 mL)
was added and the reaction mixture was washed with saturated
NaHCO3 (2ꢁ20 mL), water (20 mL) and brine (20 mL). The aqueous
phase was extracted with diethylether (2ꢁ25 mL) and the com-
bined organic phases were dried with MgSO4, concentrated in
vacuo and purified with flash column chromatography using CH2Cl2
as eluent. The product was isolated in a 54% yield as a colourless oil.
HRMS: Calculated, 212.2014. Found, 212.2018.
IR (neat): v 1654, 1616, 1527 cmꢂ1
.
4.5.3. 3,3-Dimethyl-2-methylene-N-phenylbutanamide (3c)45
Following the general procedure A, 3c was prepared in a 42%
yield as a colourless solid.
Eluent for chromatography: Isohexane: CH2Cl2 (50:50).
After chromatography, the isolated compound was dissolved in
diethyl ether (25 mL) and washed with 1 M HCl (2ꢁ25 mL). The
organic phase was dried over MgSO4 and concentrated in vacuo.
1H NMR (400 MHz, CDCl3):
d
7.55 (dd, J¼8.8, 0.8 Hz, 2H), 7.33
(dd, J¼8.8, 7.6 Hz, 2H), 7.30 (br s, 1H), 7.12 (tt, J¼7.6, 0.8 Hz,1H), 5.38
1H NMR (400 MHz, CDCl3):
d
7.37–7.31 (m, 4H), 7.26–7.22 (m,
(s, 1H), 5.34 (s, 1H), 1.26 (s, 9H).
4H), 7.21–7.16 (m, 2H), 5.57–5.52 (m, 1H), 2.33–2.18 (m, 2H), 2.14–
2.05 (m, 1H), 1.91–1.80 (m, 2H), 1.36–1.22 (m, 2H), 0.86 (s, 9H).
13C NMR (100 MHz, CDCl3):
120.0, 113.6, 35.6, 29.5.
d 169.3, 157.1, 138.1, 129.2, 124.5,
13C NMR (100 MHz, CDCl3):
d
150.8 (d, J¼7.4 Hz), 150.7 (d,
HRMS: Calculated, 204.1388. Found, 204.1392.
J¼7.4 Hz), 147.9 (d, J¼9.5 Hz), 129.9, 129.9, 125.5, 125.5, 120.3
(d, J¼5.0 Hz), 120.2 (d, J¼7.4 Hz), 111.9 (d, J¼5.6 Hz), 43.4, 32.2, 28.8
(d, J¼3.7 Hz), 27.4, 25.1 (d, J¼1.2 Hz), 24.1.
IR (neat): v 1655, 1594, 1526 cmꢂ1. Mp: 94–97 ꢀC.
4.5.4. 3,3-Dimethyl-2-methylene-N-(3-phenylpropyl)-
butanamide (3d)
HRMS: Calculated, 387.1725. Found, 387.1723.
Following the general procedure A, 3d was prepared in a 47%
yield as a colourless oil.
4.3. General procedure A
Eluent for chromatography: CH2Cl2.
To
a
2–5 mL microwave vial Herrmann’s palladacycle
1H NMR (400 MHz, CDCl3):
d 7.31–7.28 (m, 2H), 7.22–7.17 (m,
(0.025 equiv), HP(t-Bu)3BF4 (0.05 equiv), Mo(CO)6 (0.5 equiv),
amine (3 equiv), alkenyl chloride, -bromide or -phosphate (1 equiv)
and THF (2 mL) were added. DBU (3 equiv) was added and the vial
was sealed with a Teflon coated septum. The vial was heated in
a single-mode microwave reactor for 20 min and then cooled to
room temperature. The reaction was concentrated in vacuo and
purified with flash column chromatography.
3H), 5.59 (br s, 1H), 5.16–5.15 (m, 1H), 5.13–5.12 (m, 1H), 3.32 (dt,
J¼6.0, 7.0 Hz), 2.69–2.65 (m, 2H), 1.91–1.83 (m, 2H), 1.19 (s, 9H).
13C NMR (100 MHz, CDCl3):
d 171.5, 157.0, 141.6, 128.6, 128.5,
126.1, 112.5, 39.1, 33.5, 31.5, 29.4.
HRMS: Calculated, 246.1858. Found, 246.1856.
IR (neat): v 1645, 1617, 1523 cmꢂ1
.
4.5.5. N-(2-(1H-Indol-3-yl)ethyl)-3,3-dimethyl-2-methylene-
butanamide (3e)
4.4. General procedure B
Following the general procedure A, 3e was prepared in a 35%
yield as a light yellow solid.
To a 2–5 mL microwave vial palladium acetate (0.025 equiv),
Xphos (0.075 equiv), Mo(CO)6 (0.5 equiv), amine (3 equiv), alkenyl
triflate (1 equiv) and THF (2 mL) were added. DBU (3 equiv) was
added, the reaction mixture was flushed with nitrogen, and sealed
with a Teflon coated septum. The vial was heated in a single-mode
microwave reactor for 20 min and then cooled to room tempera-
ture. The reaction was concentrated in vacuo and purified with
flash column chromatography.
Eluent for chromatography: CH2Cl2.
1H NMR (400 MHz, CDCl3):
d 8.04 (br s, 1H), 7.64–7.61 (m, 1H),
7.38 (dt, J¼1.0, 8.1 Hz,1H), 7.24–7.19 (m,1H), 7.15–7.11 (m,1H), 7.06–
7.04 (m, 1H), 5.65 (br s, 1H), 5.10–5.09 (m, 1H), 5.07–5.06 (m, 1H),
3.68–3.62 (m, 2H), 3.02 (dt, J¼6.7, 1.0 Hz, 2H), 1.17 (s, 9H).
13C NMR (100 MHz, CDCl3):
d 171.5, 156.9, 136.6, 122.3, 122.2,
119.6, 118.9, 113.1, 112.8, 111.4, 39.6, 35.2, 29.5, 25.6.
HRMS: Calculated, 271.1810. Found, 271.1807.
IR (neat): v 1589, 1553 cmꢂ1. Mp: 139–141 ꢀC.
4.5. Experimental data and characterization of
compounds 3a–3x
4.5.6. 2-Adamantyl-N-benzylacrylamide (3f)
Following the general procedure A, 3f was prepared in a 62%
yield as a colourless solid.
4.5.1. N-Benzyl-3,3-dimethyl-2-methylenebutanamide (3a)
Following the general procedure A, 3a was prepared in a 75%
yield as a colourless solid.
Eluent for chromatography: CH2Cl2/diethylether (95:5).

7650
O. Lagerlund et al. / Tetrahedron 65 (2009) 7646–7652
1H NMR (400 MHz, CDCl3):
d
7.37–7.26 (m, 5H), 5.84 (br s, 1H),
13C NMR (100 MHz, CDCl3):
d 168.5, 133.8, 133.2, 43.6, 39.7, 32.3,
5.20 (s, 1H), 5.12 (s, 1H), 4.48 (d, J¼6 Hz, 2H), 2.02 (br s, 3H), 1.84 (d,
31.7, 29.8, 27.3, 27.2, 26.8, 26.0, 23.8, 22.7, 14.2.
HRMS: Calculated, 266.2484. Found, 266.2487.
IR (neat): v 1663, 1618, 1537 cmꢂ1. Mp: 52–54 ꢀC.
J¼2.8 Hz, 6H), 1.74–1.67 (m, 6H).
13C NMR (100 MHz, CDCl3):
d 171.2, 157.4, 138.6, 128.9, 128.0,
127.7, 112.7, 43.6, 42.3, 41.1, 37.3, 37.2, 36.8, 28.7.
HRMS: Calculated, 296.2014. Found, 296.2009.
4.5.12. 4-tert-Butyl-N-phenylcyclohex-1-enecarboxamide (3l)
Following the general procedure A, 3l was prepared in a 43%
yield and following general procedure B, in a 55% yield as a light
brown solid.
4.5.7. 2-Adamantyl-N-hexylacrylamide (3g)
Following the general procedure A, 3g was prepared in a 51%
yield as a light yellow solid.
Eluent for chromatography: CH2Cl2.
Eluent for chromatography: CH2Cl2/diethylether (95:5).
After chromatography, the isolated compound was dissolved
in diethyl ether (25 ml) and washed with 1 M HCl (2ꢁ25 mL).
The organic phase was dried over MgSO4 and concentrated in
vacuo.
1H NMR (400 MHz, CDCl3):
d
5.61 (br s, 1H), 5.11 (d, J¼0.8 Hz,
1H), 5.04 (d, J¼0.8 Hz, 1H), 3.23 (dt, J¼7.2, 6 Hz, 2H), 1.98 (br s, 3H),
1.79 (d, J¼2.8 Hz, 6H), 1.70–1.63 (m, 6H), 1.52–1.45 (m, 2H), 1.32–
1.25 (m, 6H), 0.85 (t, J¼6.8 Hz, 3H).
1H NMR (400 MHz, CDCl3):
d 7.58–7.54 (m, 2H), 7.43 (br s, 1H),
13C NMR (100 MHz, CDCl3):
d 171.4, 157.6, 112.0, 41.0, 39.9, 37.0,
7.34–7.29 (m, 2H), 7.12–7.08 (m, 1H), 6.75–6.72 (m, 1H), 2.60–2.52
(m, 1H), 2.32–2.21 (m, 2H), 2.01–1.91 (m, 2H), 1.35–1.22 (m, 2H),
0.90 (s, 9H).
36.8, 31.5, 29.7, 28.6, 26.7, 22.6, 14.1.
HRMS: Calculated, 290.2484. Found, 290.2491.
IR (neat): v 1641, 1618, 1520 cmꢂ1. Mp: 67–70 ꢀC.
13C NMR (100 MHz, CDCl3):
d 166.7, 138.2, 134.9, 134.0, 129.1,
124.2, 120.1, 43.5, 32.3, 27.4, 27.3, 26.0, 23.8.
HRMS: Calculated, 258.1858. Found, 258.1855.
IR (neat): v 1655, 1628, 1598, 1532 cmꢂ1. Mp: 71–74 ꢀC.
4.5.8. 2-Adamantyl-N-phenylacrylamide (3h)
Following the general procedure A, 3h was prepared in a 20%
yield as a colourless solid.
Eluent for chromatography: CH2Cl2/diethylether (80:20).
4.5.13. N-Benzyl-2-(naphthalen-1-yl)acrylamide (3m)
Following the general procedure A, 3m was prepared in a 38%
yield as a light yellow solid.
1H NMR (400 MHz, CDCl3):
d 5.13 (s, 1H), 4.96 (s, 1H), 3.43 (br s,
4H), 2.00 (br s, 3H), 1.86 (br s, 4H), 1.80 (d, J¼2.8 Hz, 6H), 1.73–1.65
(m, 6H).
Eluent for chromatography: Pentane, then CH2Cl2, then
diethylether.
13C NMR (100 MHz, CDCl3):
37.4, 36.8, 28.7, 20.6, 20.4.
d 170.5, 156.0, 111.1, 40.9, 40.5, 41.4,
1H NMR (400 MHz, CDCl3):
d 7.89–7.85(m, 3H), 7.55–7.46 (m,
HRMS: Calculated, 260.2014. Found, 260.2009.
3H), 7.42 (dd, J¼7.0, 1.4 Hz, 1H), 7.07–7.04 (m, 2H), 6.77 (d, J¼2.1 Hz,
IR (neat): v 1601 cmꢂ1. Mp: 67–68 ꢀC.
1H), 5.71 (d, J¼2.1 Hz, 1H), 5.69 (br s, 1H), 4.43 (d, J¼6.0 Hz, 2H).
13C NMR (100 MHz, CDCl3):
d 166.4, 142.6, 138.1, 135.0 133.8,
4.5.9. 2-Adamantyl-1-(pyrrolidin-1-yl)prop-2-en-1-one (3i)
Following the general procedure A, 3i was prepared in a 27%
yield as a colourless solid.
131.8, 129.3, 128.6, 128.5, 128.2, 127.8, 127.5, 127.4, 127.3, 126.9,
126.6, 125.6, 43.8.
HRMS: Calculated, 288.1388. Found, 288.1392.
Eluent for chromatography: Isohexane/CH2Cl2 (50:50).
1H NMR (400 MHz, CDCl3):
d
7.54 (dd, J¼8.4, 1.2 Hz, 2H), 7.33
4.5.14. N-Hexyl-2-(naphthalen-1-yl)acrylamide (3n)
Following the general procedure A, 3n was prepared in a 33%
yield as a light brown solid.
(dd, J¼8.4, 7.6 Hz, 2H), 7.24 (br s, 1H), 7.11 (tt, J¼7.6, 1.2 Hz, 1H), 5.35
(s, 1H), 5.24 (s, 1H), 2.03 (br s, 3H), 1.89 (d, J¼2.8 Hz, 6H), 1.75–1.68
(m, 6H).
13C NMR (100 MHz, CDCl3):
d 169.3, 157.6, 138.1, 129.2, 124.5,
Eluent for chromatography: CH2Cl2, then CH2Cl2/diethylether
(90:10).
119.9, 113.1, 41.1, 37.5, 36.8, 28.7.
1H NMR (400 MHz, CDCl3):
d 7.91–7.87 (m, 2H), 7.86–7.83 (m,
HRMS: Calculated, 282.1858. Found, 282.1852.
1H), 7.54–7.47 (m, 3H), 7.40 (dd, J¼6.9, 1.3 Hz, 1H), 6.72 (d, J¼2.1 Hz,
1H), 5,65 (d, J¼2.1 Hz,1H), 5.35 (br s,1H), 3.19 (dt, J¼7.2, 6.0 Hz, 2H),
1.34–1.25 (m, 2H), 1.20–1.05 (m, 6H), 0.80 (t, J¼7.2 Hz, 3H).
4.5.10. N-Benzyl-4-tert-butylcyclohex-1-enecarboxamide (3j)
Following the general procedure A, 3j was prepared in a 42%
yield and following general procedure B, in a 54% yield as
a colourless oil.
13C NMR (100 MHz, CDCl3):
d 166.2, 142.7, 135.3, 133.8, 131.9,
129.2, 128.5, 127.6, 126.8, 126.8, 125.7, 125.6, 40.0, 31.4, 29.3, 26.5,
22.6, 14.1.
Eluent for chromatography: CH2Cl2/diethylether (50:50).
1H NMR (400 MHz, CDCl3):
d
7.36–7.26 (m, 5H), 6.68 (t, J¼2.8 Hz,
HRMS: Calculated, 282.1858. Found, 282.1863.
IR (neat): v 1643, 1611, 1538 cmꢂ1. Mp: 70–74 ꢀC.
1H), 6.00 (br s, 1H), 4.51 (d, J¼5.6 Hz, 2H), 2.48–2.42 (m, 1H), 2.26–
2.14 (m, 2H), 1.96–1.86 (m, 2H), 1.32–1.12 (m, 2H), 0.89 (s, 9H).
4.5.15. N-Benzylcyclopent-1-enecarboxamide (3o)46
13C NMR (100 MHz, CDCl3):
d 168.3, 138.7, 134.5, 132.9, 128.8,
Following the general procedure A, 3o was prepared in a 61%
yield, as a light yellow solid. Eluent for chromatography: CH2Cl2.
128.0, 127.6, 43.8, 43.5, 32.3, 27.3, 27.2, 26.0, 23.8.
HRMS: Calculated, 272.2014. Found, 272.2019.
IR (neat): v 1659, 1612, 1539 cmꢂ1. Mp: 136–138 ꢀC.
1H NMR (400 MHz, CDCl3):
d 7.29–7.18 (m, 5H), 6.50–6.47 (m,
1H), 5.88 (br s, 1H), 4.42 (d, J¼5.8 Hz, 2H), 2.51–2.45 (m, 2H), 2.44–
4.5.11. 4-tert-Butyl-N-hexylcyclohex-1-enecarboxamide (3k)
Following the general procedure A, 3k was prepared in a 60%
yield from diethyl phosphate (1c) and a 66% yield from diphenyl
phosphate (1d). It was also prepared according to general pro-
cedure B, in a 51% yield, as a colourless oil.
2.38 (m, 2H), 1.91 (q, J¼7.7 Hz, 2H).
13C NMR (100 MHz, CDCl3):
127.6, 43.6, 33.2, 31.7, 23.5.
d 165.5, 139.2, 138.6, 128.8, 128.0,
HRMS: Calculated, 202.1232. Found, 202.1235.
IR (neat): v 1640, 1603, 1532 cmꢂ1. Mp: 107–109 ꢀC.
Eluent for chromatography: CH2Cl2/diethylether (95:5).
1H NMR (400 MHz, CDCl3):
d
6.62–6.60 (m, 1H), 5.66 (br s, 1H),
4.5.16. N-Hexylcyclopent-1-enecarboxamide (3p)
Following the general procedure A, 3p was prepared in a 61%
yield as a colourless solid.
3.29 (dt, J¼7.2, 6.0 Hz, 2H), 2.43–2.38 (m, 1H), 2.24–2.10 (m, 2H),
1.95–1.85 (m, 2H), 1.55–1.48 (m, 2H), 1.36–1.11 (8H), 0.88 (t,
J¼6.8 Hz, 3H), 0.87 (s, 9H).
Eluent for chromatography: CH2Cl2.

O. Lagerlund et al. / Tetrahedron 65 (2009) 7646–7652
7651
1H NMR (400 MHz, CDCl3):
d
6.51–6.49 (m, 1H), 5.64 (br s, 1H),
Eluent for chromatography: Isohexane/ethyl acetate (80:20).
1H NMR (400 MHz, CDCl3):
3.29 (dt, J¼7.2, 7.2 Hz, 2H), 2.56–2.50 (m, 2H), 2.50–2.43 (m, 2H),
2.02–1.93 (m, 2H), 1.50–1.47 (m, 2H), 1.31–1.26 (m, 6H), 0.87 (t,
J¼6.9 Hz, 3H).
d
7.36 (d, J¼9.2 Hz, 1H), 6.73–6.71
(m, 2H), 6.34 (t, J¼4.8 Hz, 1H), 5.83 (br s, 1H), 3.80 (s, 3H), 3.38 (dt,
J¼7.2, 6.0 Hz, 2H), 2.74 (t, J¼8.0 Hz, 2H), 2.31 (dt, J¼8.0, 4.8 Hz, 2H),
1.60–1.52 (m, 2H), 1.40–1.23 (m, 6H), 0.89 (t, J¼6.8 Hz, 3H).
13C NMR (100 MHz, CDCl3):
d 165.6, 139.5, 137.8, 39.6, 33.2, 31.7,
31.6, 29.8, 26.8, 23.5, 22.7, 14.1.
13C NMR (100 MHz, CDCl3):
d 169.1, 159.2, 138.3, 136.3, 128.3,
HRMS: Calculated, 196.1701. Found, 196.1698.
126.5, 124.5, 114.2, 111.4, 55.4, 39.8, 31.6, 29.8, 28.3, 26.8, 22.9, 22.7,
14.2.
IR (neat): v 1640, 1602, 1540 cmꢂ1. Mp: 52–54 ꢀC.
HRMS: Calculated, 288.1964. Found, 288.1970.
4.5.17. N-Benzylcinnamamide (3q)47
IR (neat): v 1733, 1640, 1604, 1528 cmꢂ1. Mp: 67–70 ꢀC.
Following the general procedure A, 3q was prepared in a 64%
yield as a light brown solid.
4.5.22. 6-Methoxy-N-phenyl-3,4-dihydronaphthalene-1-
carboxamide (3v)
Following the general procedure B, 3v was prepared in a 78%
yield as a colourless solid.
Eluent for chromatography: Pentane/ethyl acetate (70:30).
1H NMR (400 MHz, CDCl3):
d
7.61(d, J¼15.7 Hz, 1H), 7.43–7.40
(m, 2H), 7.30–7.26 (m, 8H), 6.41 (d, J¼15.7 Hz, 1H), 6.27 (br s, 1H),
4.49 (d, J¼5.9 Hz, 2H).
Eluent for chromatography: Isohexane/ethyl acetate (90:10).
13C NMR (100 MHz, CDCl3):
d
166.0, 141.4, 138.4, 134.9, 129.8,
1H NMR (400 MHz, CDCl3):
d
7.60 (d, J¼7.6 Hz, 2H), 7.52 (br s,
128.9, 128.8, 128.0, 127.9, 127.6, 120.7, 43.9.
1H), 7.43 (d, J¼8.4 Hz, 1H), 7.35 (t, J¼7.6 Hz, 2H), 7.14 (t, J¼7.6 Hz,
1H), 6.76–6.73 (m, 2H), 6.55 (t, J¼4.8 Hz, 1H), 3.82 (s, 3H), 2.80 (t,
J¼8 Hz, 2H), 2.39 (dt, J¼8.0, 4.8 Hz, 2H).
HRMS: Calculated, 238.1232. Found, 238.1237.
IR (neat): v 1746, 1651, 1616, 1541 cmꢂ1. Mp: 107–109 ꢀC.
13C NMR (100 MHz, CDCl3):
d 167.0, 159.4, 138.5, 138.1, 136.4,
4.5.18. N-Hexylcinnamamide (3r)48
Following the general procedure A, 3r was prepared in a 72%
yield as a light yellow solid.
129.9, 129.2, 126.6, 124.5, 124.1, 120.0, 114.4, 111.5, 55.4, 28.2, 23.1.
HRMS: Calculated, 280.1338. Found, 280.1343.
IR (neat): v 1745, 1651, 1594, 1527 cmꢂ1. Mp: 127–131 ꢀC.
Eluent for chromatography: CH2Cl2, then
CH2Cl2/diethylether (90:10).
4.5.23. (6-Methoxy-3,4-dihydronaphthalen-1-yl)(pyrrolidin-1-
yl)methanone (3w)
Following the general procedure B, 3w was prepared in a 73%
yield as a yellow oil.
1H NMR (400 MHz, CDCl3):
d
7.62 (d, J¼15.6 Hz, 1H), 7.49–7.46
(m, 2H), 7.34–7.32 (m, 3H), 6.43 (d, J¼15.6 Hz, 1H), 5.96 (br s, 1H),
3.40–3.35 (m, 2H), 1.60–1.52 (m, 2H), 1.37–1.26 (m, 6H), 0.88 (t,
J¼7.0 Hz, 3H).
Eluent for chromatography: Isohexane/ethyl acetate (50:50).
13C NMR (100 MHz, CDCl3):
d
166.1, 140.8, 135.1, 129.7, 128.9,
1H NMR (400 MHz, CDCl3):
d
7.01 (d, J¼8.0 Hz, 1H), 6.71–6.67
127.9, 121.1, 40.0, 31.6, 29.8, 26.8, 22.7, 14.1.
(m, 2H), 6.03 (t, J¼4.8 Hz, 1H), 3.79 (s, 3H), 3.61 (t, J¼6.8 Hz, 2H),
3.27 (t, J¼6.8 Hz, 2H), 2.78 (t, J¼8.0 Hz, 2H), 2.34 (dt, J¼8.0, 4.8 Hz,
2H), 1.92 (p, J¼6.8 Hz, 2H), 1.82 (p, J¼6.8 Hz, 2H).
HRMS: Calculated, 232.1701. Found, 232.1696.
IR (neat): v 1746, 1651, 1614, 1531 cmꢂ1. Mp: 45–47 ꢀC.
13C NMR (100 MHz, CDCl3):
d 169.3, 159.2, 137.6, 136.8, 125.4,
4.5.19. N-Benzyl-2-cyclohexylideneacetamide (3s)49
Following the general procedure A, 3s was prepared in a 73%
yield as a light yellow solid.
125.3, 124.3, 114.2, 111.5, 55.4, 48.3, 45.5, 28.2, 26.1, 24.7, 22.7.
HRMS: Calculated, 258.1494. Found, 258.1489.
IR (neat): v 1745, 1603 cmꢂ1
.
Eluent for chromatography: Pentane, then pentane/ethyl acetate
(70:30).
4.5.24. N-Benzylcyclohex-1-enecarboxamide (3x)46
Following the general procedure B, 3x was prepared in a 45%
yield as a yellow solid.
1H NMR (400 MHz, CDCl3):
d 7.35–7.23 (m, 5H), 5.79 (br s, 1H),
5.51 (quint, J¼1.1 Hz, 1H), 4.45 (d, J¼5.8 Hz, 2H), 2.86–2.82 (m, 2H),
2.16–2.12 (m, 2H), 1.66–1.54 (m, 6H).
Eluent for chromatography: CH2Cl2, then CH2Cl2/ethyl acetate
(80:20).
13C NMR (100 MHz, CDCl3):
d 167.0, 158.5, 138.7, 128.8, 128.0,
127.5, 115.5, 43.4, 38.0, 29.8, 28.7, 27.9, 26.4.
HRMS: Calculated, 230.1545. Found, 230.1539.
IR (neat): v 1745, 1660, 1625 cmꢂ1. Mp: 104–106 ꢀC.
1H NMR (400 MHz, CDCl3):
d 7.36–7.27 (m, 5H), 6.68–6.64 (m,
1H), 5.93 (br s, 1H), 4.51 (d, J¼5.7 Hz, 2H), 2.28–2.22 (m, 2H), 2.19–
2.12 (m, 2H), 1.72–1.65 (m, 2H), 1.63–1.55 (m, 2H).
13C NMR (100 MHz, CDCl3):
d 168.7, 138.7, 134.0, 133.2, 128.9,
4.5.20. N-Benzyl-6-methoxy-3,4-dihydronaphthalene-1-
carboxamide (3t)
Following the general procedure B, 3t was prepared in a 73%
yield as a colourless solid.
128.0, 127.6, 43.8, 25.5, 24.5, 22.3, 21.7.
HRMS: Calculated, 216.1388. Found, 216.1384.
IR (neat): v 1745, 1659, 1625, 1531 cmꢂ1. Mp: 78–80 ꢀC.
Eluent for chromatography: Isohexane/ethyl acetate (80:20).
Acknowledgements
1H NMR (400 MHz, CDCl3):
d 7.43–7.39 (m, 1H), 7.36–7.26 (m,
5H), 6.74–6.71 (m, 2H), 6.40 (t, J¼4.8 Hz, 1H), 6.13 (br s, 1H), 4.59 (d,
We thank the group of Prof. Troels Skrydstrup at Aarhus Uni-
versity for the gift of adamantyl vinyl phosphate and Dr. Aleh
Yahorau for conducting the HR-ESI-MS measurements. We also
acknowledge the Swedish Research Council and the Knut and Alice
J¼5.8 Hz, 2H), 3.79 (s, 3H), 2.77–2.72 (m, 2H), 2.35–2.29 (m, 2H).
13C NMR (100 MHz, CDCl3):
d 168.9, 159.3, 138.4, 138.3, 136.0,
128.9, 128.9, 128.0, 127.7, 126.6, 124.4, 114.2, 111.4, 55.4, 43.9, 28.2,
23.0.
´
Wallenbergs Foundation for financial support. We also thank Dr.
HRMS: Calculated, 294.1494. Found, 294.1496.
Luke Odell and Dr. Anders T. Lindhardt for useful discussions re-
garding this manuscript.
IR (neat): v 1745, 1606, 1566, 1526 cmꢂ1
.
4.5.21. N-Hexyl-6-methoxy-3,4-dihydronaphthalene-1-
carboxamide (3u)
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Following the general procedure B, 3u was prepared in a 62%
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