Efficient synthesis of β-aminoacrylates and β-enaminones catalyzed by Zn(OAc)2·2H2O

Article abstract of DOI:10.1135/cccc20051943

The direct condensation of amines with β-ketoesters and β-diketones to produce functional enamine derivatives has been investigated with zinc Lewis acid catalysts. Zn(OAc)₂·2H₂O shows good catalytic activity and leads to a chemo- and stereoselective formation of (Z)-enamine derivatives from aliphatic primary amines and ring-substituted anilines under mild conditions.

Full text of DOI:10.1135/cccc20051943

Synthesis of β-Aminoacrylates and β-Enaminones
1943
EFFICIENT SYNTHESIS OF β-AMINOACRYLATES AND β-ENAMINONES
CATALYZED BY Zn (OAc)2·2H2O
1
2,
3,
Ramandeep Kaur VOHRA , Jean-Luc RENAUD * and Christian BRUNEAU *
Institut de Chimie, UMR 6509, Organométalliques et Catalyse, Université de Rennes 1,
1
Campus de Beaulieu-35042 Rennes Cedex, France; e-mail: raman_vohra@yahoo.com,
2
3
jean-luc.renaud@univ-rennes1.fr, christian.bruneau@univ-rennes1.fr
Received Jun e 10, 2005
Accepted Septem ber 13, 2005
Th e direct con den sation of am in es with β-ketoesters an d β-diketon es to produce fun ction al
en am in e derivatives h as been in vestigated with zin c Lewis acid catalysts. Zn (OAc)2·2H2O
sh ows good catalytic activity an d leads to a ch em o- an d stereoselective form ation of (Z)-
en am in e derivatives from aliph atic prim ary am in es an d rin g-substituted an ilin es un der m ild
con dition s.
Keywords: Zin c catalysts; β-Am in oacrylates; β-En am in on es; Acrylates; En am in es; Lewis acids;
Am in es; β-Ketoesters.
β-Fun ction alized en am in e derivatives are useful precursors in syn th esis, as
th ey com bin e n ucleoph ilicity of th e en am in e an d electroph ilicity of th e
en on e m otives. Such derivatives are valuable in term ediates for th e syn th e-
sis of biologically active com poun ds, such as α-1 an d β-am in o acids2, alka-
loids3, peptides4, an d h eterocycles5. Th ey exh ibit a wide ran ge of biological
activities, an d h ave foun d application s as an ti-in flam m atory6, an titum or6a,7
,
an ticon vulsan t agen ts6a,8. β-En am in on es an d β-am in oacrylates can be ob-
tain ed eith er via th e addition of ester or am ide en olates to n itriles (m eth od
A)9, tosylim in es (m eth od B)10 an d im idoyl h alides (m eth od C)11, or th e ad-
dition of en am in es12 or ketim in es13 to activated carboxylic acid derivatives
(m eth od D) (Sch em e 1). More fun ction al derivatives substituted at th e C2
position of acrylates h ave been prepared from active m eth ylen e com poun ds
an d am ide acetals.14
Th e m ost com m on ly used route in volves a direct con den sation of am in es
with β-dicarbon yl com poun ds in an arom atic solven t with azeotropic re-
m oval of water at h igh tem perature (Sch em e 2)15,16
.
Altern atively, prim ary am in es also react with β-dicarbon yl com poun ds in
water to give en am in on es17. Som e im proved procedures h ave been reported
usin g Al2O3 18, SiO2 19, K10-m on tm orillon ite20, NaAuCl4 21, or m icro-
Collect. Czech. Chem. Commun. (Vol. 70) (2005)
doi:10.1135/cccc20051943

1944
Vohra, Renaud, Bruneau:
NR3
R2
NR3
R2
OM
OM
OR1
+
+
OR1
Cl
Method B
Method C
R3
R2
NH
O
Y
R3 = H, Ts
Y = OR1, R
Method A
Method D
NR3
R2
NHR3
R2
OM
OR1
R2
N
+
or
+
RCOX
X = Cl, Imidazole
R = Et, Bn, Imidazole
SCHEME 1
waves22. However, th ese m eth ods suffer from low selectivity (due to tran s-
form ation of th e β-ketoester in to β-ketoam ide), un satisfactory yields, an d
h arsh con dition s. Th erefore, due to th e im portan ce of th ese derivatives in
organ ic ch em istry, th e developm en t of a m ore efficien t procedure was de-
sired.
R2
R3
R1
R4
O
O
N
O
R2
TsOH, toluene, ∆
NH
R1
+
R3
OEt
OEt
-H2O
R4
SCHEME 2
Lewis acid-catalyzed reaction are n ow of great in terest because of th eir
un ique reactivity an d selectivity un der m ild con dition s23. Recen tly,
26
Zn ClO4·6H2O 24, Bi(TFA)3 in water25a or m olten salt25b, an d CeCl3·7H2O
,
were foun d to be very active for th e syn th esis of β-en am in on es or β-am in o-
acrylates.
As a part of our program directed toward th e preparation of optically active
am in e com poun ds via en an tioselective h ydrogen ation 2,27, we in vesti-
gated th e use of an efficien t Lewis acid catalyst for th e syn th esis of N-substi-
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

Synthesis of β-Aminoacrylates and β-Enaminones
1945
tuted β-am in oacrylates 3 via direct con den sation of prim ary or secon dary
am in es 2 with β-ketoester 1 (Sch em e 3).
R2
R3
R1
O
O
N
O
Lewis acid
R2
NH
R1
+
R3
OEt
OEt
R4
R4
1
2
3
SCHEME 3
RESULTS AND DISCUSSION
Th e Lewis acid-catalyzed con den sation of am in es with β-ketoesters or
β-diketon es h as recen tly been described24–26. With th e objective of carryin g
out en am in e form ation an d h ydrogen ation in on e pot, we were in terested
in a ch eap an d efficien t catalyst th at could be safely used un der reductive
con dition s in th e presen ce of h ydrogen . Th us, we tested th e activity of
various zin c salts (5 m ole %) for th e direct form ation of am in oacrylate 4
from ben zylam in e 2a (1.5 equivalen ts) an d eth yl 2-oxocyclopen tan e-
1-carboxylate 1a (1 equivalen t) in dich lorom eth an e at room tem perature in
th e presen ce of m agn esium sulfate (Table I).
O
BnNH
O
Zn salt, MgSO4
CH2Cl2, r.t.
O
+
PhCH2NH2
OEt
OEt
2a
1a
4
TABLE I
Reaction of ben zylam in e (2a) with eth yl 2-oxocyclopen tan e-1-carboxylate (1a) in th e presen ce
of zin c catalysta
Lewis Acid
Yield, %
Zn (ClO4)2·6H2O
Zn (OAc)2·2H2O
Zn (citrate)·2H2O
Zn Br2
74
90
80b
50
13
0
Zn (D-glucon ate)2·3H2O
Zn SO4·7H2O
a
Con dition s: 0.75 m m ol of ben zylam in e 2a, 0.5 m m ol of carboxylate 1a, dried MgSO4 an d
b
zin c salt (5 m ole %) in 5 m l of CH2Cl2, 2 days; 3 days.
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

1946
Vohra, Renaud, Bruneau:
It is n otable th at th e reaction does n ot occur with out a catalytic am oun t
of previously dried m agn esium sulfate, an d is very slow in th e presen ce of
sole m agn esium sulfate. Th e n ecessity of th e presen ce of such a deh ydrat-
in g agen t m igh t be related to in situ form ation of an active zin c species. In -
deed, th e required am oun t of m agn esium sulfate depen ds on ly on th e
am oun t of water presen t in th e startin g zin c salt (30 m ole % of MgSO4 for
Zn (ClO4)2·6H2O; 10 m ole % for Zn (OAc)2·2H2O).
Am on g th e differen t salts, Zn (ClO4)2·6H2O, Zn (OAc)2·2H2O, Zn Br2, an d
Zn (citrate)·2H2O appear to be th e m ost efficien t catalysts. Zn (OAc)2·2H2O,
wh ich provided th e expected am in oacrylate in 90% yield, is also th e ch eap-
est zin c salt. In addition , th is Lewis acid n ot on ly prom otes th e con den sa-
tion reaction sm ooth ly but also ch em oselectively28, as we n ever observed
th e form ation of a β-ketoam ide or β-en am in oacrylam ide.
We exten ded th is con den sation reaction of an alkylam in e to a variety of
β-ketoesters (1a–1c) an d β-diketon es (1d , 1e) with Zn (OAc)2·2H2O as th e
Lewis acid catalyst (Table II). In dich lorom eth an e at reflux, in th e presen ce
of 5 m ole % Zn (OAc)2·2H2O an d 10 m ole % MgSO4, am in oacrylate 8 was
isolated in a good yield (73%). With com poun ds 1a, 1b an d 1d , a lower
tem perature could be used. Am in oacrylates 4–7 an d 9 were obtain ed in
h igh yields (73–98%) by perform in g th e con den sation at room tem pera-
R1
Zn(OAc)·2H2O (5 mole %)
MgSO4 (10 mole %)
O
O
NH
O
R1NH2
+
R2
R4
R2
R4
CH2Cl2, r.t. or reflux
R3
1a–1e
R3
4–10
2a–2b
TABLE II
Zin c-catalyzed con den sation of alkylam in es with β-ketoesters an d β-diketon esa
Dicarbon yl
com poun d
Yield
%
R2
R3
R4
Am in e
R1
Product
Tem perature
1a
1a
1a
1a
1b
1b
1c
1d
1e
(CH2)3
(CH2)3
(CH2)3
(CH2)3
OEt
OEt
OEt
OEt
OEt
OEt
OEt
CH3
Ph
2a
2a
2b
2b
2a
2b
2a
2a
2a
Bn
Bn
4
4
r.t.
50b
r.t.
90
95b
(S)-Ph CHCH3
5
r.t.
(S)-Ph CHCH3
5
r.t.
95
CH3
CH3
Ph
H
H
H
H
H
Bn
6
r.t.
78
(S)-Ph CHCH3
7
r.t.
79
Bn
Bn
Bn
8
reflux
r.t.
73
CH3
Ph
9
98
10
reflux
n o reaction
a
Con dition s: 0.75 m m ol of am in e, 0.5 m m ol of carboxylate 1, dried MgSO4 (10 m ole %)
b
an d zin c acetate (5 m ole %) in 5 m l of CH2Cl2, 16 h . Zin c brom ide (5 m ole %) was used.
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

Synthesis of β-Aminoacrylates and β-Enaminones
1947
ture. As a lim itation of th is process, th e reaction between diketon e 1e an d
various alkylam in es did n ot occur. Th is absen ce of reactivity m igh t be due
to th e con jugation of th e carbon yl an d ph en yl groups, wh ich lead to a dra-
m atic decrease in th e electroph ilic ch aracter of th e carbon yl m oiety.
1
Th e n ucleoph ilicity of th e en am in es can be assessed by H or 13C NMR.
In deed, th e vin ylic proton s of com poun ds 6–9 are located in th e h igh -field
area (aroun d 4.3–5.0 ppm , com pared with th e usual vin ylic proton : δ >
5.5 ppm ) an d th e correspon din g carbon s in th e 13C spectra are presen t at
83–96 ppm (110–120 ppm for a usual C(sp2)).
It is n otable th at, based on literature data29, th e en am in o esters an d
en am in o keton es were isolated exclusively as th e h ydrogen -bon ded (Z)-
1
isom ers. Th us, in th e H NMR spectrum of com poun d 6, on ly a CH3 sign al
at 1.90 ppm , ch aracteristic of th e (Z)-isom ers was observed, wh ereas n o sig-
n al was detected at a lower field (δ > 2.2 ppm for th e (E)-isom ers).
In order to exten d th e scope of th e reaction , we in vestigated th e addition
of arom atic am in es 2c–2f to th e carbon yl reagen ts 1a–1e (Table III). All ex-
perim en ts were con ducted in dich lorom eth an e at reflux usin g 1 equivalen t
R1
Zn(OAc)2·2H2O (5 mole %)
MgSO4 (10 mole %)
O
O
NH
O
R1NH2
+
R2
R4
R2
R4
CH2Cl2, reflux
R3
1a–1e
TABLE III
Zin c-catalyzed con den sation of arom atic am in es with β-ketoesters an d β-diketon esa
R3
2c–2f
11–22
Dicarbon yl
com poun d
Reaction
tim e, days
Yield
%
R2
R3
R4
Am in e
R1
Product
1a
1a
1a
1a
1b
1b
1b
1b
1c
1c
1d
1e
(CH2)3
(CH2)3
(CH2)3
(CH2)3
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
CH3
Ph
2c
2d
2e
2f
2c
2d
2e
2f
2c
2f
2c
2c
Ph
11
12
13
14
15
16
17
18
19
20
21
22
2
4
3
5
2
2
2
2
4
4
2
5
99
3,4,5-(MeO)3C6H2
75
2,4,6-Me3C6H2
45
4-IC6H4
36
CH3
CH3
CH3
CH3
Ph
H
H
H
H
H
H
H
H
Ph
57
3,4,5-(MeO)3C6H2
55
2,4,6-Me3C6H2
69
4-IC6H4
Ph
21
53
Ph
4-IC6H4
Ph
42
CH3
Ph
86
Ph
n o reaction
a
Con dition s: 0.75 m m ol of am in e, 0.5 m m ol of carboxylate 1, dried MgSO4 (10 m ole %)
an d zin c acetate (5 m ole %) in 5 m l of CH2Cl2.
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

1948
Vohra, Renaud, Bruneau:
of β-ketoesters 1a–1c or β-diketon es 1d , 1e, 1.5 equivalen ts of an am in e in
th e presen ce of 5 m ole % of Zn (OAc)2·2H2O, an d previously dried MgSO4
(10 m ole %). As sh own in Table III, th e yields were usually lower th an th ose
obtain ed with alkyl am in es. Th ey ran ged from 21% for 18 to 86% for 21
an d 99% for 11. Th e steric h in dran ce on th e arom atic rin g h as n o real in -
fluen ce on th e yield (cf., e.g., th e yields in th e syn th esis of 15, 18 or 19).
Th e in fluen ce of electron ic properties seem s to be m ore im portan t. Th us,
with an ilin e, th e an ilin oacrylates were produced in up to 99% yields (11,
15, 19, 21), wh ereas, with 4-iodoan ilin e, th e correspon din g products (14,
18, 20) were isolated in m oderate yields ran gin g from 21 to 42%. As also
previously observed with alkylam in es, n o reaction occurred between an ar-
om atic am in e an d th e diketon e 1e.
CONCLUSION
We h ave sh own th at Zn (OAc)2·2H2O, an in expen sive zin c salt, was able to
catalyze th e con den sation of prim ary alkylam in es an d rin g-substituted an i-
lin es with β-ketoesters an d β-diketon es un der safe an d m ild con dition s, pro-
vidin g a straigh tforward an d selective route to am in oacrylate an d en am in -
on e derivatives in m oderate to very good yields.
EXPERIMENTAL
1H an d 13C NMR spectra were recorded on 200 MHz Bruker AC 200 spectrom eters. Ch em ical
sh ifts are reported in ppm (δ-scale) referen ced to th e residual proton reson an ces of th e sol-
ven ts. Couplin g con stan ts (J) are given in Hz. Mass spectra (MS) were obtain ed on a GC-MS
Hewlett–Packard HP 5971 apparatus. Th in -layer ch rom atograph y (TLC) was perform ed on
Merck silica gel 60 F 254 plates. Silica gel Merck Geduran SI (40–63 µm ) was used for colum n
ch rom atograph y. For com poun ds 5, 19, 20, th e proton of th e am in e was n ot observed in
th e proton NMR spectrum .
Gen eral Procedure for th e Preparation of Am in oacrylates
Magn esium sulfate was first h eated at 200 °C un der vacuum over 15 m in . To th is previously
dried m agn esium sulfate (10 m ole %), zin c acetate (5 m ole %), dich lorom eth an e
(5 m l/m m ol), th e dicarbon yl derivative (1 equiv.), an d fin ally a prim ary am in e (1.5 equiv.)
were successively added un der argon . Th e reaction m ixture was stirred at room tem perature
or at reflux un til com pletion , as detected by TLC an alysis. Th e solution was th en filtered
th rough Celite, an d con cen trated un der vacuum . Th e crude oily m ixture was purified on
silica gel by flash ch rom atograph y (eluen t: h eptan e/eth yl acetate, 7:3).
Ethyl 2-(benzylamino)cyclopent-1-ene-1-carboxylate (4). 1H NMR (200.13 MHz, CDCl3):
1.26 t, 3 H, J = 7.1; 1.78 quin t, 2 H, J = 7.7; 2.53 m , 4 H; 4.15 q, 2 H, J = 7.1; 4.35 d, 2 H, J =
6.3; 7.15–7.40 m , 5 H; 7.84 br s, 1 H (NH). 13C NMR (50.3 MHz, CDCl3): 14.4, 20.5, 28.8,
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

Synthesis of β-Aminoacrylates and β-Enaminones
1949
31.6, 47.9, 53.2, 93.0, 126.3 (2 C); 126.8, 128.3 (2 C); 138.9, 164.1, 168.0. HRMS: calculated
for C15H19NO2: 245.14158, foun d: 245.1409.
Ethyl 2-[((S)-1′-phenylethylamino)]cyclopent-1-ene-1-carboxylate (5). 1H NMR (200.13 MHz,
CDCl3): 1.26 t, 3 H, J = 7.2; 1.46 d, 3 H, J = 6.8; 1.72 m , 2 H; 2.25 m , 1 H; 2.48 t, 2 H, J =
7.4; 2.55 m , 1 H; 4.18 q, 2 H, J = 6.8; 4.52 q, 1 H, J = 7.2; 7.24 m , 5 H; 7.82 br s, 1 H (NH).
13C NMR (50.3 MHz, CDCl3): 14.8, 20.9, 24.9, 28.9, 32.3, 54.3, 58.5, 93.5, 125.5 (2 C);
127.0, 128.7 (2 C); 145.3, 164.2, 168.6. HRMS: calculated for C16H21NO2: 259.15723, foun d:
259.1577.
Ethyl 3-(benzylamino)but-2-enoate17,20 (6). 1H NMR (200.13 MHz, CDCl3): 1.25 t, 3 H, J =
7.1; 1.90 s, 3 H; 4.10 q, 2 H, J = 7.1; 4.40 d, 2 H, J = 6.4; 4.55 s, 1 H; 7.31 m , 5 H; 8.98 s,
1 H (NH). 13C NMR (50.3 MHz, CDCl3): 14.4, 19.1, 46.6, 58.1, 83.0, 126.7 (2 C); 127.1,
128.5 (2 C); 138.6, 161.6, 170.3. IR (ν, cm –1): 1658, 1600. HRMS: calculated for C13H17NO2:
219.12593, foun d: 219.1244.
Ethyl 3-[((S)-1′-phenylethylamino)]but-2-enoate (7). 1H NMR (200.13 MHz, CDCl3): 1.28 t,
3 H, J = 7.1; 1.52 d, 3 H, J = 6.8; 1.78 s, 3 H; 4.18 q, 2 H, J = 7.1; 4.50 s, 1 H; 4.62 q, 1 H, J =
7.1; 7.31 m , 5 H; 8.99 s, 1 H (NH). 13C NMR (50.3 MHz, CDCl3): 15.1, 20.1, 25.4, 53.3, 58.8,
83.6, 125.8 (2 C); 127.5, 129.2 (2 C); 145.4, 161.9, 171.1.
Ethyl 3-(benzylamino)-3-phenylacrylate (8). 1H NMR (200.13 MHz, CDCl3): 1.28 t, 3 H, J =
7.1; 4.21 q, 2 H, J = 7.1; 4.30 d, 2 H, J = 6.5; 4.70 s, 1 H; 7.29 m , 10 H; 8.91 br s, 1 H (NH).
13C NMR (50.3 MHz, CDCl3): 14.5, 48.3, 58.8, 86.2, 126.8 (2 C); 127.1, 127.8 (2 C); 128.3
(2 C); 129.0 (2 C); 129.2, 136.0, 139.2, 164.7, 170.3. HRMS: calculated for C18H19NO2:
281.14158, foun d: 281.1408.
4-(Benzylamino)pent-3-en-2-one20 (9). 1H NMR (200.13 MHz, CDCl3): 1.91 s, 3 H; 2.03 s,
3 H; 4.43 d, 2 H, J = 6.4; 5.03 s, 1 H; 7.31 m , 5 H; 8.91 br s, 1 H (NH). 13C NMR (50.3 MHz,
CDCl3): 19.3, 29.3, 47.1, 96.3, 127.1 (3 C); 128.0, 129.2 (2 C); 138.4, 164.0.
Ethyl 2-anilinocyclopent-1-ene-1-carboxylate (11). 1H NMR (200.13 MHz, CDCl3): 1.32 t, 3 H,
J = 7.2; 1.87 quin t, 2 H, J = 7.6; 2.60 t, 2 H, J = 7; 2.82 t, 2 H, J = 7.5; 4.22 q, 2 H, J = 7.1;
7.08 m , 3 H, J = 6.8; 7.29 m , 2 H, J = 7.9; 9.68 br s, 1 H (NH). 13C NMR (50.3 MHz, CDCl3):
15.1, 22.2, 29.2, 34.1, 59.4, 98.1, 121.1 (2 C); 123.5, 129.6 (2 C); 141.1, 160.8, 168.9.
Ethyl 2-(3,4,5-trimethoxyanilino)cyclopent-1-ene-1-carboxylate (12). 1H NMR (200.13 MHz,
CDCl3): 1.24 t, 3 H, J = 6.0; 1.97 m , 2 H; 2.35 m , 2 H; 2.55 m , 1 H; 2.80 m , 1 H; 3.81 s, 3 H;
3.82 s, 6 H; 4.18 q, 2 H, J = 6.0; 6.30 s, 2 H; 10.21 s, 1 H (NH). 13C NMR (50.3 MHz, CDCl3):
14.6, 22.2, 29.1, 34.0, 56.0 (2 C); 59.4, 61.4, 97.8, 99.3 (2 C); 135.1 (2 C); 153.3 (2 C); 161.0,
168.9. HRMS: calculated for C17H23NO5: 321.15762, foun d: 321.1579.
Ethyl 2-(2,4,6-trimethylanilino)cyclopent-1-ene-1-carboxylate (13). 1H NMR (200.13 MHz,
CDCl3): 1.28 t, 3 H, J = 7.1; 1.80 quin t, 2 H, J = 7.3; 2.25 m , 2 H; 2.28 s, 6 H; 2.30 s, 3 H;
2.60 t, 2 H, J = 7.2; 4.24 q, 2 H, J = 7.1; 6.85 s, 2 H; 8.47 br s, 1 H (NH). 13C NMR
(50.3 MHz, CDCl3): 15.1, 18.4 (2 C); 21.0, 21.1, 29.4, 32.8, 59.6, 98.9, 127.1 (2 C); 129.1
(2 C); 136.6, 140.1, 164.3, 168.6. HRMS: calculated for C17H23NO2: 273.17288, foun d:
273.1724.
Ethyl 2-(4-iodoanilino)cyclopent-1-ene-1-carboxylate (14). 1H NMR (200.13 MHz, CDCl3):
1.28 t, 3 H, J = 7.1; 1.90 quin t, 2 H, J = 7.4; 2.58 t, 2 H, J = 7.4; 2.80 t, 2 H, J = 7.4; 4.20 q,
2 H, J = 7.1; 6.80 d, 2 H, J = 8.7; 7.58 d, 2 H, J = 8.7; 9.61 s, 1 H (NH). 13C NMR (50.3 MHz,
CDCl3): 15.0, 22.2, 29.1, 34.0, 59.5, 99.8, 122.6 (2 C); 129.9, 138.4 (2 C); 140.9, 154.3,
159.9.
Ethyl 3-anilinobut-2-enoate17,20,22 (15). 1H NMR (200.13 MHz, CDCl3): 1.21 t, 3 H, J = 6.4;
1.99 s, 3 H; 4.10 q, 2 H, J = 6.4; 4.78 s, 1 H; 7.10 m , 5 H; 10.35 s, 1 H (NH). 13C NMR
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

1950
Vohra, Renaud, Bruneau:
(50.3 MHz, CDCl3): 14.6, 20.4, 58.7, 86.1, 124.4 (2 C); 124.9, 129.3 (2 C); 139.4, 159.0,
170.4. HRMS: calculated for C12H15NO2: 205.11028, foun d: 205.1118.
Ethyl 3-(3,4,5-trimethoxyanilino)but-2-enoate (16). 1H NMR (200.13 MHz, CDCl3): 1.24 t,
3 H, J = 6.0; 1.97 s, 3 H; 3.81 s, 3 H; 3.82 s, 6 H; 4.18 q, 2 H, J = 6.4; 4.62 s, 1 H; 6.30 s, 2 H;
10.21 s, 1 H (NH). 13C NMR (50.3 MHz, CDCl3): 14.6, 20.3, 56.2 (2 C); 58.8, 61.1, 85.7, 92.7
(2 C); 135.1 (2 C); 153.3 (2 C); 159.2, 171.0. HRMS: calculated for [M – CH3]+ (m ain peak)
C
14H18NO5: 280.11850, foun d: 280.1193.
Ethyl 3-(2,4,6-trimethylanilino)but-2-enoate (17). 1H NMR (200.13 MHz, CDCl3): 1.28 t, 3 H,
J = 7.2; 1.62 s, 1 H; 2.20 t, 6 H, J = 5.5; 2.31 s, 2 H; 4.18 q, 2 H, J = 7.1; 4.72 s, 1 H; 6.80 s,
2 H; 6.95 s, 3 H; 9.71 s, 1 H (NH).
Ethyl 3-(4-iodoanilino)but-2-enoate (18). 1H NMR (200.13 MHz, CDCl3): 1.29 t, 3 H, J = 7.1;
2.02 s, 3 H; 4.15 q, 2 H, J = 7.1; 4.78 s, 1 H; 6.86 d, 2 H, J = 8.4; 7.65 d, 2 H, J = 8.4.
13C NMR (50.3 MHz, CDCl3): 14.4, 19.1, 59.4, 87.6, 89.5, 117.7 (2 C); 126.3, 138.5 (2 C);
139.7, 161.6, 170.3.
Ethyl 3-anilino-3-phenylacrylate (19). 1H NMR (200.13 MHz, CDCl3): 1.28 t, 3 H, J = 7.0;
4.21 q, 2 H, J = 7.0; 4.99 s, 1 H; 6.65 d, 2 H, J = 6.8; 6.98 t, 1 H, J = 7.3; 7.11 t, 2 H, J = 7.5;
7.30 m , 3 H; 7.49 t, 1 H; 7.98 d, 1 H, J = 7.1. 13C NMR (50.3 MHz, CDCl3): 14.9, 59.7, 91.6,
122.6 (2 C); 126.4, 128.6 (2 C); 128.8 (2 C); 128.9 (2 C); 129.9, 136.4, 140.8, 159.5, 170.5.
Ethyl 3-(4-iodoanilino)-3-phenylacrylate (20). 1H NMR (200.13 MHz, CDCl3): 1.31 t, 3 H, J =
7.1; 4.21 q, 2 H, J = 7.2; 5.02 s, 1 H; 6.42 d, 2 H, J = 8.7; 7.23–7.50 m , 5 H; 7.98 d, 2 H, J =
7.1. 13C NMR (50.3 MHz, CDCl3): 14.9, 59.9, 92.7, 124.2 (2 C); 126.4, 128.9 (2 C); 129.0
(2 C); 130.1, 134.2, 137.9 (2 C); 140.7, 158.7, 170.4.
4-Anilinopent-3-en-2-one17,20 (21). 1H NMR (200.13 MHz, CDCl3): 1.98 s, 3 H; 2.11 s, 3 H;
5.19 s, 1 H; 7.22 m , 5 H. 13C NMR (50.3 MHz, CDCl3): 20.3, 29.6, 98.0, 125.2 (2 C); 125.9,
129.5 (2 C); 139.1, 160.6, 196.6.
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