Gold versus silver-catalyzed amination of allylic alcohols

Article abstract of DOI:10.1016/j.jorganchem.2010.09.072

Direct substitution of the hydroxy group in allylic alcohols by different nitrogenated nucleophiles is performed using low loadings of cationic gold(I) or silver salts as catalysts. Sulfonamides, carbamates and aromatic amines can be used as nucleophiles. Comparative studies between the best catalysts, cationic (triphenylphosphite)gold(I) complex and silver triflate, demonstrate that the former catalyst shows, in general, better performance than silver, working at lower loadings, in shorter reaction times and at lower temperatures. Representative allylic alcohols are used giving good γ-regioselectivity, specially in the case of penta-1,4-dien-3-ol and (E)-1-phenylbut-2-en-1-ol affording the corresponding allylic sulfonamides with total regio and stereoselectivity by a hydroamination mechanism. In the case of crotyl alcohol and (E)-4-phenylbut-3-en-2-ol mainly and exclusively α-substituted sulfonamides were obtained, respectively, by a cationic mechanism.

Full text of DOI:10.1016/j.jorganchem.2010.09.072

Journal of Organometallic Chemistry 696 (2011) 357e361
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Gold versus silver-catalyzed amination of allylic alcohols
Xavier Giner, Paz Trillo, Carmen Nájera*
Departamento de Química Orgánica, Facultad de Ciencias, and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo 99, 03080 Alicante, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 17 August 2010
Received in revised form
Direct substitution of the hydroxy group in allylic alcohols by different nitrogenated nucleophiles is
performed using low loadings of cationic gold(I) or silver salts as catalysts. Sulfonamides, carbamates and
aromatic amines can be used as nucleophiles. Comparative studies between the best catalysts, cationic
27 September 2010
(
triphenylphosphite)gold(I) complex and silver triflate, demonstrate that the former catalyst shows, in
general, better performance than silver, working at lower loadings, in shorter reaction times and at lower
temperatures. Representative allylic alcohols are used giving good -regioselectivity, specially in the case
Accepted 28 September 2010
Available online 8 October 2010
g
Dedicated to Professor Maria Teresa Chicote
on occasion of his 60th birthday
of penta-1,4-dien-3-ol and (E)-1-phenylbut-2-en-1-ol affording the corresponding allylic sulfonamides
with total regio and stereoselectivity by a hydroamination mechanism. In the case of crotyl alcohol and
(
E)-4-phenylbut-3-en-2-ol mainly and exclusively
a-substituted sulfonamides were obtained, respec-
Keywords:
tively, by a cationic mechanism.
Gold(I) complexes
Silver triflate
Ó 2010 Elsevier B.V. All rights reserved.
Allylic alcohols
amination
nucleophilic substitution
1. Introduction
2. Results and discussion
Direct nucleophilic substitutions using allylic alcohols as elec-
trophilic substrates and nitrogenated compounds as nucleophiles
constitute a straightforward access to allylic amines. This strategy is
a green atom economy process, which use ready available starting
materials and generates water as by-product [1]. In order to activate
the hydroxy function as leaving group Brønsted acids such as
sulfonic acids [2] and Lewis acids such as iodine [3], transition
metal complexes or salts from Pd(0) [4], Pt(II) [5], Mo(VI) [6], Bi(III)
The reaction between (E)-1,3-diphenylprop-2-en-1-ol (1a) with
p-toluenesulfonamide (2a) as a model reaction was studied using
different cationic gold(I) complexes and silver salts at room
temperature during 1 h (Table 1). The first experiment was carried
out with 0.5 mol% of (Ph
3
P) AuCl/AgOTf as catalyst in dioxane giving
the expected product 3aa in 75% yield (Table 1, entry 1). The same
experiment described by Liu et al. [8a] in THF afforded product 3aa in
76% yield but after 12 h and with 5 mol% catalyst loading. Using
[7], Au(III) [8], and Au(I) [8,9] have been used as catalysts. Inter and
3
dioxane as solvent the complex [(PhO) P] AuCl/AgOTf (0.5 mol%)
intramolecular gold-catalyzed reactions have been performed with
p-toluenesulfonamide and different anilines as nucleophiles [8] as
well as with 1-methylimidazolidin-2-one and related nucleophiles
gave higher 93% yield than the former one (Table 1, compare entry 1
and 2). Again, triphenyl phosphite formed a more cationic gold(I)
complex than triphenylphosphine [10]. When AgOTf was used as
catalyst even with 2 mol% loading only 45% crude yield was obtained
[9]. However, the nucleophilic substitution of allylic alcohols with
nitrogenated nucleophiles using silver salts as catalysts has not
been described. We recently reported that cationic (triphenyl-
phosphite) gold(I) complexes [10] and silver triflate [11] are good
catalysts for the challenging intermolecular hydroamination of
alkenes and dienes. In this paper we describe comparative studies
about the intermolecular amination of allylic alcohols with
different nitrogenated compounds using gold and silver catalysts.
(Table 1, entry 3). Both reactions were performed with [(PhO)
3
P]
AuCl/AgSbF and AgSbF , respectively, instead of AgOTf giving better
6
6
yield only in the last case (Table 1, entries 4 and 5). Comparison
studies with other solvents such as acetonitrile or nitromethane
using either [(PhO) P] AuCl/AgOTf or AgOTf, lower yields were
3
obtained with the cationic gold complex. However, in the case of
employing AgOTf in acetonitrile a better 78% yield than in dioxane
was obtained (Table 1, entries 6e9). In general, cationic gold
complexes and specially the triphenylphosphite derivative showed
better catalytic performance than silver salts, which needed higher
loading under the same reaction conditions.
*
Corresponding author. Tel.: þ34 96 5903728; fax: þ34 96 5903549.
E-mail address: cnajera@ua.es (C. Nájera).
0
022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.09.072

358
X. Giner et al. / Journal of Organometallic Chemistry 696 (2011) 357e361
ꢀ
Table 1
benzyl carbamate (2f) the amination was carried out at 25 C using
mol% of both catalysts affording product 3af in 93% and 40% yield
Table 2, entries 11 and 12, respectively). Electron-poor anilines are
Amination of 1,3-diphenylprop-2-en-1-ol (1a) with p-toluenesulfonamide catalyzed
2
(
by Au(I) or AgX.a
Au(I) or AgX
appropriate reagents for this nucleophilic substitution, thus
p-chloroaniline (2g) reacted at 50 C to afford product 3ag in good
yields using 2 mol% of both catalysts (Table 2, entries 13 and 14). In
the case of p-nitroaniline (2h) the substitution with gold as catalyst
Ph
Ph
OH
Ph
Ph
+
TsNH2
ꢀ
solvent, rt, 1 h
2a
NHTs
1
a
3aa
was performed at rt and with only 0.5 mol% loading (Table 2, entry
ꢀ
1
5). However, AgOTf needed 2 mol% loading and 50 C to reach the
Entry
Cat (Mol %)
(Ph P)AuCl/AgOTf (0.5)
[(PhO) P]AuCl/AgOTf (0.5)
AgOTf (2)
Solvent
Yield (%)b
same yield than the gold complex (Table 2, entry 16). In the case of
the electron-rich p-toluidine (2i) high catalyst loadings, 2 and 5 mol
for gold and silver, respectively, 1 d reaction time and heating at
0 C were necessary to afford moderate 45 and 44% yields (Table 2,
1
2
3
4
5
6
7
8
9
3
dioxane
dioxane
dioxane
dioxane
dioxane
75
93
45
77
63
65
78
74
70
3
%
5
ꢀ
[(PhO)
3
P]AuCl/AgSbF
(2)
6
(0.5)
AgSbF
[(PhO)
6
entries 17 and 18).
3
P]AuCl/AgOTf (0.5)
CH
CH
CH
CH
3
CN
3
CN
3
NO
3
NO
Different representative allylic alcohols 1b-1f were submitted to
direct amination with p-toluenesulfonamide (2a) in dioxane and in
AgOTf (2)
[(PhO) P]AuCl/AgOTf (0.5)
AgOTf (2)
3
2
2
the presence of either [(PhO)
3
P]AuCl/AgOTf or AgOTf as catalysts
(
Table 3). Aliphatic alcohols such as (E)-but-2-en-1-ol (1b) and
a
Reaction conditions: allyl alcohol 1a (1 mmol), TsNH
2
2a (1.5 mmol), cat. (see
penta-1,4-dien-3-ol (1c) needed higher temperatures and catalysts
loading than (E)-1,3-diphenylprop-2-en-1-ol (1a). Crotyl alcohol
ꢀ
column) and solvent (2 mL), 25 C, 1 h.
b
Isolated yield of the crude product (calculated from 1H-NMR).
(1b) afforded a 1:2 mixture of the g and a-substituted allylic
sulfonamides 3ba and 3’ba in 50% overall yield using 1 mol% of the
Next, different type of nucleophiles were essayed using
,3-diphenylprop-2-en-1-ol (1a) as allylic substrate and either
gold complex and 5 mol% of AgOTf under rather high temperature
85 and 110 C, respectively (Table 3, entries 1 and 2). When penta-
ꢀ
1
[
(PhO) P] AuCl/AgOTf or AgOTf as catalysts (Table 2). The reactions
3
1,4-dien-3-ol (1c) was submitted to react with 2a the g-substituted
were performed with 2 eq. of sulfonamides, benzyl carbamate and
anilines in dioxane, catalyst loading and reaction conditions being
optimized for each nucleophile. Electron-rich sulfonamides 2ae2c
reacted at rt in the presence of either the gold (0.5 mol%) or the
silver (2 mol%) catalyst (Table 2, entries 1e6). However p-nitro-
product 3ca was regio and stereoselectively obtained, although
with moderate yields even working with 5 mol% of catalysts at 50
ꢀ
and 85 C (Table 3, entries 3 and 4, respectively). Similar results
were obtained when cyclohex-2-en-1-ol (1d) was allowed to react
with p-toluenesulfonamide (2a) in the presence of the gold and the
silver catalysts (Table 3, entries 5 and 6). Product 3da was isolated
in both cases in 67% yield using 1 and 2 mol% of each catalyst at 50
benzenesulfonamide (2d) afforded 3ad in very good yields using
ꢀ
2
8
mol% of catalyst loading during 1 d at 50 C (Table 2, entries 7 and
ꢀ
). Methanesulfonamide (2e) needed also the reaction to be heated
at 50 C and to increase the cationic gold complex to 2 mol% to
and 100 C, respectively. In the case of the regioisomeric alcohols
ꢀ
(E)-4-phenylbut-3-en-1-ol (1e) and (E)-1-phenylbut-2-en-1-ol (1f)
the same product 3ea was regio and stereoselectively obtained
provide 3ae in good yields (Table 2, entries 9 and 10). In the case of
Table 2
a
Amination of (E)-1,3-diphenylprop-2-en-1-ol (1a) with different nucleophiles catalyzed by Au(I) or AgX.
Au(I) or AgX
Ph
Ph
OH
1
2
Ph
Ph
+
R R NH
dioxane, T (ºC), t
1
2
2
NR R
1
a
3aa-3ai
1
2
ꢀ
Yield (%)b
Entry
R R NH (No.)
Cat. (mol%)
[(PhO) P]AuCl/AgOTf (0.5)
AgOTf (2)
[(PhO) P]AuCl/AgOTf (0.5)
AgOTf (5)
[(PhO) P]AuCl/AgOTf (0.5)
AgOTf (2)
[(PhO) P]AuCl/AgOTf (2)
AgOTf (2)
[(PhO) P]AuCl/AgOTf (0.5)
AgOTf (2)
[(PhO) P]AuCl/AgOTf (2)
AgOTf (2)
[(PhO) P]AuCl/AgOTf (2)
AgOTf (2)
[(PhO) P]AuCl/AgOTf (0.5)
AgOTf (2)
[(PhO) P]AuCl/AgOTf (2)
AgOTf (5)
T ( C)
Time
Product No.
1
2
3
4
5
6
7
8
9
p-MeC
p-MeC
p-MeC
p-MeC
p-MeOC
p-MeOC
p-NO
p-NO
MeSO
MeSO
BnCO
BnCO
p-ClC
p-ClC
p-NO
p-NO
p-CH
p-CH
6
6
6
6
4
H SO
4
H SO
4
H SO
4
H SO
2
2
2
2
NH
NH
NHMe(2b)
NHMe(2b)
2
2
(2a)c
(2a)c
3
25
25
25
25
25
25
50
50
50
50
25
25
50
50
25
50
50
50
1 h
1 h
3aa
3aa
3ab
3ab
3ac
3ac
3ad
3ad
3ae
3ae
3af
3af
3ag
3ag
3ah
3ah
3ai
84 (93)
78 (77)
70 (95)
50 (58)
65 (87)
(85)
77 (80)
96 (98)
82 (82)
75 (85)
93 (95)
40 (75)
90 (95)
80 (84)
90 (95)
94 (95)
45 (47)
44 (45)
d
3
90 min
25 h
40 min
24 h
24 h
24 h
4 h
1 h
1 h
8 h
24 h
24 h
7 h
24 h
24 h
24 h
6
H
H
4
SO
SO
2
NH
NH
2
(2c)
(2c)
3
6
4
2
2
2
C
C
6
H
H
4
4
2
2
SO
SO
(2e)
(2e)
(2f)
(2f)
2
NH
NH
2
2
(2d)
(2d)
3
2
6
2
2
NH
NH
3
10
11
12
13
14
15
16
17
18
2
2
NH
NH
2
3
2
2
6
H
6
H
4
NH
NH
2
(2g)
(2g)
3
4
2
2
C
C
6
H
4
NH
NH
2
(2h)
(2h)
(2i)
3
2
6
H
4
2
3
C
C
6
H
H
4
NH
NH
2
3
3
6
4
2
(2i)
3ai
a
b
c
1 2
Reaction conditions: allyl alcohol 1a (1 mmol), R R NH 2 (2 mmol), cat. (see column) and dioxane (2 mL).
Isolated yield after column chromatography. In parenthesis isolated crude yield determined by 1H-NMR.
2
1.5 equiv of TsNH were used.
d
In acetonitrile.

X. Giner et al. / Journal of Organometallic Chemistry 696 (2011) 357e361
359
Table 3
Gold(I) versus Ag-catalyzed amination of allylic alcohols with p-toluenesulfonamide.
a
ꢀ
Yield (%)b
Entry
Alcohol (No.)
Cat. (mol%)
T ( C)
Time (h)
48
Product (No.)
(
3’ba)
1
[(PhO)
3
P]AuCl/AgOTf (1)
85
50c (54c)
(1b)
(
3ba)
2
3
4
(1b)
AgOTf (5)
110
50
24
24
24
(3ba)
48c (50c)
36 (37)
40
3
[(PhO) P]AuCl/AgOTf (5)
(
3ca)
(1c)
(1c)
AgOTf (5)
85
5
[(PhO)
3
P]AuCl/AgOTf (1)
50
8
67 (70)
(
1d)
(3da)
(3da)
6
7
8
9
(1d)
AgOTf (2)
100
25
50
25
50
8
24
24
24
24
67
[(PhO)
3
P]AuCl/AgOTf (2)
84 (90)
90 (95)
84 (95)
94 (98)
(1e)
(3ea)
(3ea)
(1e)
AgOTf (5)
[(PhO)
3
P]AuCl/AgOTf (2)
(3ea)
(3ea)
(1f)
10
(1f)
AgOTf (5)
a
b
c
Reaction conditions: allyl alcohol 1 (1 mmol), p-toluenesulfonamide (2a) (342 mg, 2 mmol), cat. (see column) and dioxane (2 mL).
Isolated yield after flash chromatography (hexaneeEtOAc). In parenthesis isolated crude yield (calculated from 1H-NMR).
Combined yield of a 1:2 mixture of 3ba and 3’ba.
(
Table 3, entries 7e10). Surprisingly, 1e gave the
product and 1f the -substituted, respectively under similar high
yields and reaction conditions (Table 3, compare entry 7 and 9 with
and 10). The gold-catalyzed reactions needed 2 mol% loading and
a
-substituted
This type of
Maseras for the gold(I)-catalyzed isomerisation of allylic ethers
[12]. This mechanism can explain the -attack of the nucleophile 2a
to alcohol 1f to afford product 3ea. Metal-coordinate alcohol 1f,
complex I, can suffer anti-hydroamination to afford intermediate II,
p-activation has been also proposed by Paton and
g
g
8
was performed at rt, whereas the silver-catalyzed amination
a higher 5 mol% loading and heating at 50 C must be used.
ꢀ
2
which after anti-elimination of H O and further decoordination of
The regiochemical outcome of the gold- or silver-catalyzed
amination of allylic alcohols can be explained using alcohols 1e and
the catalyst afforded product 3ea. This proposed pathway can also
explain the formation of products 3ba and 3ca.
1
f as model substrates (Scheme 1). According to experimental
studies performed by Mukherjee and Widenhoefer [9] in the gold
I)-catalyzed amination of allylic alcohols with cyclic ureas as
Forthetransformationofalcohol1eintothea-substitutedproduct
3ea two different isomerisation mechanisms have been proposed [9].
One possible explanation is the isomerisation of alcohol 1e into 1f
mediated by the gold- or silvercatalyst acting asLewis acids involving
carbocationic intermediates (Scheme 2, eq. (1)). Thisprocesshas been
observed in the case of 3-methylbut-2-en-1-ol, which isomerizes
under the presence of a cationic gold(I) catalyst into 2-methylbut-3-
(
nucleophiles two main possible mechanisms can be proposed. The
first proposed mechanism is shown in Scheme 1 involving
a hydroamination reaction of the CeC double bond instead of
a concerted S
0
N
2 substitution by
s
-activation of the hydroxyl group.
This pathway seems to be more plausible due to the low oxophi-
en-2-ol [9]. The same authors found out isomerisation of the
g- to the
licity of gold(I) and silver against
p-activation of the double bond.
a-aminated product. In the case of alcohol 1e, it can be proposed that
once the g-substitution takes place to give product 3’ea further gold-
or silver-catalyzed isomerisation would form 3ea (Scheme 2, eq. (2)).
These processes can explain the formation of product 3’ba as well.
+
[M+]
[
M ]
+
[
M ]
TsNH
2
Ph
Ph
Ph
HO
+
[
M ]
Ph
Ph
Ph
OH
OH
.
+ TsNH2
eq. 1
.
.
1
f
I
HNHTs
Ph
NHTs
OH
OH
1e
1f
[M+]
3ea
[M]
Ph
HO
Ph
-
H O
2
+
[M ]
Ph
Ph
TsNH2
[M+]
Ph
+
H
.
N.
.
HTs
-[M+]
.
.
.
.
NHTs
.
HO
NHTs
3ea
eq. 2
.
H
OH
e
NHTs
NHTs
1
II
III
3'ea
3ea
Scheme 1. Proposed mechanism for the
g-substitution of allylic alcohol 1f.
Scheme 2. Proposed mechanisms for the a-substitution of allylic alcohol 1e.

360
X. Giner et al. / Journal of Organometallic Chemistry 696 (2011) 357e361
3
. Conclusions
4.2.1. (E)-N-(1,3-Diphenylallyl)-4-methoxybenzenesulfonamide
3ac)
f
White solid; m.p. 118 C; R (hexane/ethyl acetate: 4/1) 0.28; n
(
ꢀ
We can conclude that the intermolecular amination of allylic
alcohols can be carried out not only in the presence of catalytic
amounts of thecationic (triphenylphosphite)gold(I)complex butalso
with silver triflate. This process can be carried out using different
nitrogenated compounds such as sulfonamides, benzyl carbamate
and aromatic amines. Electron-deficient anilines and electron-rich
sulfonamides are the best nucleophiles for these metal-based
nucleophilic substitutions. In general AgOTf-catalyzed aminations
neededhigherloadings, temperatures,andlongerreactiontimesthan
(KBr) 3267, 3082, 3024, 2999, 2839, 1589, 1495, 1444, 1423, 1267,
ꢂ1
1147, 1089, 1049, 825, 741, 687, 676 cm
H
; d (300 MHz) 3.75 (s, 3H),
5.06e5.10 (m, 2H), 6.1 (dd, J ¼ 15.7, 6.3 Hz, 1H), 6.4 (d, J ¼ 15.7 Hz,
1H), 6.8 (d, J ¼ 8.8 Hz, 2H), 7.20e7.23 (m, 10H), 7.7 (d, J ¼ 8.8 Hz,
2H);
d
C
(75 MHz) 55.5, 59.8, 113.9, 126.5, 127.0, 127.9, 128.2, 128.4,
þ
128.7, 132.1, 132.2, 139.6, 162.7; m/z(EI): 379 [M , 2%], 209 (17), 208
(100), 207 (15), 204 (40),192 (10),115 (17),104 (28), 91 (13), 77 (20).
gold-catalyzed ones. The substitution seems to occur through a
activation pathway of the double bond followed by hydroamination
and elimination of H O and the cationic catalyst affording the
substituted product. Alternatively, the formation of -substituted
products can be explained by isomerisation of the initially formed
p
-
4.2.2. (E)-N-(1,3-Diphenylallyl)-4-nitrobenzenesulfonamide (3ad)
ꢀ
Yellow solid; m.p. 160 C; R
f
(hexane/ethyl acetate: 4/1) 0.34;
n
2
g-
(KBr) 3278, 3100, 3057, 3021, 1607, 1524, 1415, 1339, 1310, 1154,
ꢂ1
a
1086, 1024, 846 cm
H
; d (400 MHz) 5.06e5.51 (m, 2H), 6.08 (dd,
g-
J ¼ 15.8, 6.7 Hz, 1H), 6.40 (d, J ¼ 15.8 Hz, 1H), 7.05e7.51 (m, 10H),
substituted product or by alcohol isomerisation, both processes being
catalyzed by Au(I) or Ag(I) involving cationic intermediates.
7.85 (d, J ¼ 9.0 Hz, 2H), 8.10 (d, J ¼ 9.0 Hz, 2H);
d
C
(100 MHz) 29.7,
60.2, 123.9, 126.4, 127.1, 127.3, 128.3, 128.4, 128.6, 128.9, 133.0, 135.4,
þ
1
38.7, 146.6, 149.6; m/z (EI) 394 [M , 4%], 209 (10), 208 (64), 207
4
. Experimental
(59), 206 (100), 193 (13), 192 (26), 181 (12), 178 (13), 165 (11), 130
21), 122 (10), 115 (29), 105 (15), 104 (63), 103 (18), 91 (25), 77 (23).
(
4.1. General
4
.2.3. (E)-N-(1,3-Diphenylallyl) methanesulfonamide (3ae)
ꢀ
Unless otherwise noted all commercials reagents and dry
White solid; m.p. 127 C; R
f
(hexane/ethyl acetate: 4/1) 0.30;
n
solvents were used without further purification. All reactions were
carried out in absence of light and under argon atmosphere.
Melting points were determined with a Reichert Thermovar hot
plate apparatus. IR spectra were recorded on a Nicolet 510 P-FT
(KBr) 3293, 3032, 3006, 2930, 1495, 1459, 1430, 1415, 1314, 1042,
ꢂ1
966, 759, 745, 698 cm
H
; d (300 MHz) 2.77 (s, 3H), 4.97 (d,
J ¼ 6.8 Hz, 1H), 5.30 (t, J ¼ 6.8 Hz, 1H), 6.32 (dd, J ¼ 15.7, 6.8 Hz, 1H),
6.62 (d, J ¼ 15.7 Hz, 1H), 7.31e7.40 (m, 10H);
d
C
(75 MHz) 42.2, 59.7,
1
13
spectrophotometer. H-NMR (300 or 400 MHz) and C-NMR (75 or
00 MHz) spectra were obtained on a Bruker AC-300 and Bruker
AC-400, respectively, using CDCl as solvent and TMS as internal
126.6, 127.1, 128.2, 128.3, 128.4, 128.7, 129.0, 132.5, 135.8, 139.8; m/z
þ
1
(EI) 287 [M , 6%], 208 (47), 207 (48), 206 (100), 192 (27), 191 (12),
3
178 (11), 165 (10), 130 (17), 115 (22), 104 (43), 103 (13), 91 (14), 77
(15).
standard. Low-resolution electron impact (EI) mass spectra were
obtained at 70 eV on an Agilent 5973 Network. Analytical TLC was
performed on Merck aluminium sheets with silica gel 60 F254. Silica
gel 60, (0.04e0.06 mm) was employed for flash chromatography.
Gas chromatographic analyses were performed on an Agilent
4.2.4. (E)-Benzyl 1,3-diphenylallylcarbamate (3af)
ꢀ
White solid; m.p. 110 C; R
f
(hexane/ethyl acetate: 4/1) 0.39;
n
(KBr) 3412, 3318, 3263, 3191, 3086, 3057, 3031, 2948, 1959, 1694,
ꢂ1
6
890N instrument equipped with a WCOT HPe1 fused silica
1604, 1528, 1448, 1342, 1288, 1234, 1064, 962, 727 cm
; d
H
capillary column.
(300 MHz) 5.15 (t, J ¼ 7.1 Hz, 1H), 5.54 (s, 1H), 6.33 (dd, J ¼ 15.9,
6
.0 Hz, 1H), 6.56 (d, J ¼ 16 Hz, 1H), 7.10e7.49 (m, 15H);
d
C
(75 MHz)
4.2. General procedure for the gold(I)- and silver(I)-amination of
66.9, 126.5, 127.0, 127.7, 128.1, 128.2, 128.5, 128.8, 129.0, 131.2, 135.2,
þ
allylic alcohols
136.5, 140.9, 142.1, 156.7; m/z (EI): 343 [M , 2%], 253 (19), 252 (96),
235 (16), 209 (30), 208 (12), 206 (25), 193 (17), 192 (28), 191 (86),
To a (1:1) mixture of gold catalyst or silver salt (see, Tables 1e3)
and nucleophile (1.5e2 mmol, see Tables 1e3) in dry solvent (2 mL)
was added the alcohol (1 mmol) with magnetic stirring under
argon atmosphere in the dark. After the corresponding reaction
time under the conditions indicated in Tables 1e3, water (2 mL) and
brine (2 drops) were added to the reaction mixture. The organic
layer was separated and the aqueous phase was extracted with
ethyl acetate (2 ꢁ 10 mL). All organic phases were mixed, dried with
181 (14), 178 (14), 165 (13), 130 (14), 115 (32), 108 (12), 105 (10), 104
(43), 103 (17), 91 (100), 79 (17), 77 (28), 65 (12).
Acknowledgments
We thank the financial support from the Spanish Ministerio de
Ciencia e Innovación (MICINN) (projects CTQ 2007-62771/BQU and
Consolider Ingenio 2010, CSD2007-00006), the Generalitat Valenci-
ana (PROMETEO 2009/039), FEDER and the University of Alicante.
MgSO
flash chromatography.
The compound
benzenesulfonamide (3’ba) is commercially available. The
following compounds (E)-N-(1,3-diphenylallyl)-4-methyl-
4
and evaporated (15 Torr). Pure products were obtained by
(E)-N-(but-2-enyl)-4-methyl-
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(
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