Access to 1,3-oxazine-2,4-diones/1,3-thiazine-2,4-diones: Via organocatalytic CO2/COS incorporation into allenamides

Article abstract of DOI:10.1039/c9ob02398d

Organocatalyzed [4 + 2] annulation of CO₂/COS with allenamides is firstly reported to synthesize 1,3-oxazine-2,4-diones and 1,3-thiazine-2,4-diones in moderate to excellent yields under mild reaction conditions. The catalytic potential of a series of Lewis base CO₂ and COS adducts are particularly noted for this process, which features high regio- A nd chemo-selectivity, step-economy, facile scalability, and easy product derivatization. This study offers the potential for the application of organocatalytic systems for CO₂ and COS chemical transformation.

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Access to 1,3-Oxazine-2,4-diones/1,3-thiazine-2,4-diones via
Organocatalytic CO2/COS Incorporation into Allenamides
Received 00th January 20xx,
Accepted 00th January 20xx
Hui Zhou,* Rui Wang, Hui Zhang, Wei Chen and Xiao-Bing Lu
DOI: 10.1039/x0xx00000x
Organocatalyzed [4+2] annulation of CO2/COS with allenamides is firstly reported to synthesize 1,3-oxazine-2,4-diones and
1,3-thiazine-2,4-diones in moderate to excellent yields under mild reaction conditions. The catalytic potential of a series of
Lewis base CO2 and COS adducts are particularly noted for this process, which features high regio- and chemo-selectivity,
step-economy, facile scalability, and easy product derivatization. This study offers the potential for the application of
organocatalytic systems for CO2 and COS chemical transformation.
www.rsc.org/
Introduction
111
The development of efficient catalytic transformation of
carbon dioxide (CO2) to high-value-added chemicals and
polymers, has received more and more attention from both
academics and industry.1 Carbonyl sulfide (COS) is another
trace gas in the atmosphere, which is easily oxidized to SO2 in
the troposphere, thus leading to significant environment
harm.2 Along with the rapid development of the modern
industry, the anthropogenic COS release is increasing obviously,
so practical attempts are being undertaken towards the
potential transformation of COS to reduce emissions.3 As CO2-
like molecules, some activation modes and catalytic systems
for COS conversion have been successfully developed with
reference of CO2-related research achievements.3-4
Six-membered heterocyclic compounds, such as 1,3-oxazine-
2,4-diones and 1,3-thiazine-2,4-diones, are important scaffolds
found in medicinal chemistry. For example, some of them have
been practically used as antiulcer agents, anticonvulsant drug,
anesthetic agent and herbicides in chemical science, as shown
in scheme 1.5 Using CO2 or COS as a useful and sustainable C1
synthon, direct [4+2] annulation to construct functionalized
O
O
O
O
S
Ar
O
COOH
O
O
N
O
NH
S
N
N
O
O
O
Et
Et
Et
n
antiulcer agent anticonvulsant drug
herbicides
anesthetic agent
Scheme 1. Representative bioactive 1,3-oxazine-2,4-diones and 1,3-
thiazine-2,4-diones.
2,4-diones/1,3-thiazine-2,4-diones in a green and sustainable
manner, is highly desired.
Lewis base-COX (X=O/S) adducts as an emerging type of
organocatalytic systems have been rapidly developed by our
group,7 especially for catalytic [3+2] annulation of COX with
propargylic compounds, such as propargylic alcohol,
propargylic amines and propargylic amides as substrates to
construct value-added five membered heterocyclic compounds
under mild reaction conditions.8 Taking inspiration from these
studies, we are curious whether suitable Lewis base-COX
adducts might display significantly catalytic activity for the
synthesis of six-membered heterocyclic compounds. Herein,
we firstly report the direct [4+2] annulation of CO2/COS with
allenamides in the presence of CO2/COS adducts of N-
heterocyclic olefins as organocatalysts, to selectively
synthesize 1,3-oxazine-2,4-diones and 1,3-thiazine-2,4-diones
under mild reaction conditions.
1,3-oxazine-2,4-diones/1,3-thiazine-2,4-diones is
a
very
promising approach. To the best of our knowledge, up to now,
the only precedent is the stoichiometric cyclization reaction of
CO2 with allenamides to synthesize 1,3-oxazine-2,4-diones in
the presence of K2CO3 or Cs2CO3, as reported by Ma et al.6
Thus, the development of a catalytic method for rapid
construction of structurally diverse substituted 1,3-oxazine-
Results and discussion
Initially, the annulation of CO2 with N-benzyl 4-methyl-2,3-
pentadienamide 2a as the model reaction was evaluated, as
shown in Table 1. A series of LB-CO2 adducts (1a-1k), including
N-heterocyclic carbenes-CO2 adducts (NHC-CO2), imidazole-
derived highly polarized alkenes-CO2 adducts (NHO-CO2), and
pyrimidine-derived highly polarized alkenes-CO2 adducts
a. State Key Laboratory of Fine Chemical, Dalian University of Technology, Dalian,
116024, PR China. E-mail: zhouhui@dlut.edu.cn
†Electronic Supplementary Information (ESI) available: Experimental spectroscopic
data for all new compounds, thermogravimetric analysis data and crystal data. See
DOI: 10.1039/x0xx00000x
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DOI: 10.1039/C9OB02398D
Table 2. LB-CO2 1k catalyzed annulation of different 2,3-allenamides with CO2.a
T
able 1. Optimization of the reaction conditions for [4+2] annulation of 2a
with CO2.a
O
R1
R3
O
O
N
R2
O
CO2
0.1 MPa
Cat.1k (5.0 mol%)
60 oC, 2 h, DMSO (0.5 mL)
R1
Bn
O
Cat.
(5 mol%)
+
O
N
O
HN
R3
O
CO2
+
HN
Bn
solvent, t, T
R2
3
2
0.1 MPa
2a
3a
Entry
1
Substrate
R1
R2
-Et
R3
Yield (%)b
93
N
R1
N
N
O
R2
R1
N
O
N
O
R2
R2
2b
2c
2d
2e
2f
-Me
-Me
-Et
-Bn
-Bn
-Bn
-Bn
-Bn
-Bn
-Bn
-nBu
-iPr
N
R1
O
O
R3
O
2
-nHex
-Et
87
A
(
) NHC-CO2
3
96
C
B
(
) THPE-CO2
(
) NHO-CO2
R1 = R2 = -
R1 = R2 = -
R1 = R2 = -iPr
1a
:
Dip
: R1 = -Me; R2 = -H
=
R1 R2 = -Me
R1 = -Bu; R2 = -H
: R1 = -Bn; R2 = -H
4
-Me
-iPr
89
1
; R2 = R3 = -Me
Dip
1h
1d
1b
:
Mes
: R = -
1
: R = -
; R2 = -Et; R3 = -Me
; R2 = -iPr; R3 = -Me
R3 = -Me
1i
:
1e
1f
Dip
Dip
R2
1c
:
5
-(CH2)5-
-(CH2)4-
-Ph
99
R1 = -
1
1j
:
Dip
:
= 2,6-diisopropylphenyl
= 2,4,6-trimethylphenyl
1k
1g
Mes
: R
=
=
6
2g
2h
2i
99
Yield (%)b
7
-Me
-Me
-Me
-Me
-Et
99
Entry
Cat.
1a
1b
1c
1d
1e
1f
Solvent
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
THF
T (oC)
25
25
25
25
25
25
25
25
25
25
25
25
25
25
t (h)
2
5
5
8
-Me
-Me
-Me
-Et
97
1
9
2j
50
17a/46c
2
3
2
19
16
11
6
2
10
11
2k
2l
-cycloHex
-CH2C≡CH
4
2
78
5
2
a
The reaction was carried out using 0.5 mmol of 2 and 5.0 mol% of Cat.1k in
DMSO with a CO2 balloon at 60 oC for 2 h. The yields were determined by 1H
NMR analysis with 1,2,4,5-tetramethylbenzene as the internal standard. c The
reaction was conducted at 100 oC for 6 h.
b
6
2
5
7
1g
1h
1i
2
13
14
6
8
2
CO2 adducts were mandatory for this carboxylic cyclization
(entry 18).
9
2
10
11
12
13
14
15
16
17
18
1j
2
The substrate scope of the reaction was then explored using
DMSO as solvent and working at 5.0 mol % 1k loading, 60 °C,
and 0.1 MPa of CO2, as standard conditions (Table 2). Variation
of R1 and R2 unit using ethyl, iso-propyl, n-hexyl, cyclo-pentyl,
cyclo-hexyl or phenyl groups resulted in no obvious influence
on the results, delivering the corresponding 3a-3h in good to
excellent yields. Then, the alteration of R3 moiety was
investigated. When the R3 group was substituted with n-butyl
group, the corresponding product 3i was afforded in 93% yield.
However, when the R3 group was changed to iso-propyl or
cyclo-hexyl group, 3j and 3k were obtained in only moderate
yields, even at 100 oC for 6h, presumably due to steric
hindrance. It is worth noting that 2,3-allenamide containing
propargyl group on the nitrogen atom (2l) was also well
tolerated to provide the corresponding 3l as the sole product,
and no five-membered oxazolidinone was detected.
36
33
5
1k
1k
1k
1k
2
2
CH3CN
DMF
2
31
15
90
91
NRc
2
1k
1k
1k
DCM
DMSO
DMSO
25
25
60
2
24
2
-
DMSO
25
2
a The reaction was carried out using 0.5 mmol of 2a and 5.0 mol% of Cat. in
DMSO (0.5 mL) with a CO2 balloon at 25 oC for 2 h. Determined by 1 H NMR
b
c
spectroscopy with 1,2,4,5-tetramethylbenzene as the internal standard. No
Reaction.
(THPE-CO2), were employed as organocatalysts for this
transformation. The catalytic runs were directly performed in
DMSO solution and monitored by H NMR spectroscopy, using
1
Having established LB-CO2 catalyzed [4+2] annulation of CO2
with allenamides, COS was further introduced for this process
in the presence of the corresponding COS adducts of LB as
organocatalysts. The experiment results indicated that LB-COS
catalyzed [4+2] annulation of COS with allenamides could
5.0 mol % loading of LB-CO2 adducts, working at 25 °C and
atmospheric pressure of CO2. For NHC-CO2 catalytic systems,
N-alkyl 1c (entry 3) showed higher activity than N-aryl 1a and
1b (entries 1 and 2), and 6-isopropyl-1,3-oxazine-2,4-dione 3a
as the desired product, was obtained in 19% yield.
Furthermore, the highly polarized alkenes-CO2 adducts were
evaluated (entries 4-11) and the most satisfactory result was
obtained with 1k (entry 11). When changing the solvent to
THF, CH3CN, DMF or DCM, the yield was decreased in different
level under the same conditions (entries 12-15). Meanwhile,
prolonging the reaction time to 24 h or increasing reaction
o
effectively carry out at 60 C and 1.0 MPa of COS. LB-COS
adduct S1j showed the highest activity to selectively obtain 6-
isopropyl-1,3-thiazine-2,4-dione 4a with 96% yield (see
Supporting Information for details). With optimal conditions in
hand, the substrate scope was then screened and the results
are demonstrated in Table 3. Variation of R1 and R2 unit had no
obvious influence on the results, and the corresponding 4b-4h
were generated in good to excellent yields. Whereas, the steric
o
temperature to 60 C could improve the yield of 3a obviously
(entries 16 and 17). Control experiments also revealed that LB-
2 | J. Name., 2012, 00, 1-3
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O
Table 3. LB-COS S1j catalyzed annulation of different 2,3-allenamides
N
R3
O
with COS.a
X
N
N
R
R1
O
O
X
R1
N
R2
R3
Cat. S1j
(5.0 mol%)
THPE-COX adduct
R1
S
N
R3HN
N
R2
O
COS
+
R1
O
O
Bn
1.0 MPa 60 oC,12 h, CH3CN
O
HN
S

R3
R2
R2
2
4
Cat. S1j
N
N
N
O
N
R
O
O
O
N
H
R
O
O
N
X
S
NBn
O
H
O
S
NBn
O
S
NBn
X
R
R3
O
X
NR3
H
O
nHex
X
N
O
NR3
O
R1
(A)
(D)
(C)

R1
R2
4b: Yield: 99%

R1
4c: Yield: 98%
4a: Yield: 96%
R2
R2
O
O
O
O
C
X
S
NBn
O
S
NBn
O
S
NBn
O
N
O
C
X
O
N
4d: Yield: 92%
4e: Yield: 93%
4f: Yield: 87%
R
X
O
H
O
O
O
(B)
X
S
NBn
O
S
NBn
O
S
NnBu
NR3
O
Ph
O

R1
4i: Yield: 32%; 99%(b)
R2
4g: Yield:64%
4h: Yield: 98%
Scheme 2. Proposed mechanism
O
O
O
S
N
S
N
S
N
Based on the mechanistic studies (Supporting Information
Scheme S1, and Figure S2-S21) and previous literatures,6,9 the
possible mechanistic pathway is shown in Scheme 2. Firstly,
THPE-COX adducts should act primarily as a base to activate
allenamides, thus generating intermediate A. Furthermore,
intermediate A may attack the carbon atom of free CO2/COS to
form carbamate/thiocarbamate B. Alternatively, intermediate
B could also be generated by intramolecular nucleophilic
attack of allenamide N-position onto the THPE-COX adduct to
form intermediate D, and followed activation of another free
COX.9 Then, the intramolecular nucleophilic addition from the
carbamate/thiocarbamate anion to the allene central carbon
and the subsequent pronation of the alkyl anion lead to the
O
O
O
4k: Yield: 0; 98%(b)
4j: Yield: 0; 94%(b)
4l: Yield:97%
O
O
O
S
N
Ts
S
N
Ts
S
N
Ts
Ph
Ph
Ph
O
O
O
Ph
4n: Yield: 99%
H
4o: Yield: 98%
4m: Yield: 98%
a
General reaction conditions: substrate 2 (0.5 mmol), THPE-COS adduct
Cat. S1j (5.0 mol%), COS (1.0 MPa), CH3CN (0.8 mL), 60 oC, 12 h. Determined
by 1H NMR spectroscopy with 1,2,4,5-tetramethylbenzene as the internal
standard. b 100 oC, DMSO (0.4 mL).
demand of the N-substituents strongly influences the reaction
rate. Only 32% yield of 4i was achieved with the N-butylated
substrate 2i, whereas no desired products were detected for
the N-isopropyl and cyclohexyl substrates. Gratifyingly, the
target products 4i-4k could be generated in high yields when
O
O
O
HO
HO
H2N
N
NBn
O
N
NBn
O
N
NBn
O
o
increasing the reaction temperature to 100 C. Noting that N-
propargyl 2l and tosylmethyl substrates (2m-2o) were well-
tolerated in this process, affording the desired products 4l-4o
in excellent yields. Moreover, the final structure proof of 4h
was unequivocally determined by single-crystal X-ray
diffraction analysis (Figure 1).
5, 95%
5
, 84%
6, 33%
2
(III)
(IV)
-NH
2
H2N
NH
H2N
OH
O
OH
(V)
(I)
(II)
O
O
2a (1.0 g, 5 mmol)
Cat. 1k (5 mol%)
2a (1.66 g, 6.64 mmol)
Cat.S1j (5 mol%)
S
NBn
NBn
O
CO2
0.1 MPa
COS
DMSO, 60 oC, 2 h
O
60 oC, 12 h,
CH3CN
1.0 MPa
4a, 91%
3a, 87%
(VI)
BnNH
(VIII)
(VII)
O
AlCl3
S
AlCl3
O
2
BnN NBn
7a, 58%
7b, 41%
O
O
+
O
NH
NH
O
O
O
O
BnHN
N
NHBn
9, 73%
8, 93%
Bn
Scheme 3. Gram-scale synthesis and chemical transformations of 3a and 4a.
III: 3a, ethanolamine, EtOH, reflux, 24 h; IV: 4a, ethanolamine, EtOH, reflux,
24 h; V: 4a, NH2NH2, EtOH, reflux, 4 h; VI: 4a, benzylamine, EtOH, reflux, 22
h; VII: 4a, AlCl3, benzene, 50 oC, 2 h; VIII: 3a, AlCl3, benzene, 50 oC, 4 h. (see
Supporting Information for detailed experimental procedures)
Figure 1. X-ray crystallographic structure of 4h.
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formation of 1,3-oxazine-2,4-diones/1,3-thiazine-2,4-diones Hz, 1H), 1.74 – 1.63 (m, 1H), 1.52 (dp, J = 14.3, 7.2VHiezw,A1rtHicl)e,O1n.l2in0e
13
DOI: 10.1039/C9OB02398D
and regeneration of free THPE-COX adducts.
(d, J = 6.9 Hz, 3H), 0.92 (t, J = 7.4 Hz, 3H). C NMR (126 MHz,
To further demonstrate the utility of the annulation CDCl3) δ 171.63, 161.49, 149.23, 135.69, 129.30, 128.55,
reaction, we conducted the gram-scale synthesis of 3a and 4a 128.07, 99.67, 44.98, 39.06, 26.53, 16.91, 11.40.
in 87% and 91%, respectively (Scheme 3. I and II). Moreover,
3c. Colorless liquid. (Following the procedure for the
the products can be easily transformed to other synthetically preparation of 3a, eluent: petroleum ether / ethyl acetate =
1
useful building blocks. When using various primary amines as 5:1) H NMR (400 MHz, CDCl3) δ 7.48 (dd, J = 7.9, 1.6 Hz, 2H),
external nucleophiles, oxazine-2,4-diones 3a and thiazine-2,4- 7.38 – 7.25 (m, 3H), 5.74 (s, 1H), 5.03 (s, 2H), 2.46 (h, J = 6.9
dione 4a were easily converted in one step to functionalized Hz, 1H), 1.71 – 1.60 (m, 1H), 1.54 – 1.37 (m, 1H), 1.28 (dd, J =
pyrimidine-2,4-diones (5-7), which are a class of the most 11.9, 5.6 Hz, 8H), 1.19 (d, J = 6.9 Hz, 3H), 0.87 (t, J = 6.9 Hz, 3H).
important heterocycles exhibiting remarkable pharmacological 13C NMR (101 MHz, CDCl3) δ 171.89, 161.53, 135.71, 129.34,
activity.10 Furthermore, the debenzylation of 3a and 4a could 128.55, 128.08, 99.52, 44.98, 37.61, 33.56, 31.62, 29.07, 26.96,
smoothly carry out to form 9 and 8 in 73% and 93%, 22.59, 17.41, 14.05. HRMS(ESI): calcd for C19H26NO3: 316.1913
respectively.
[M+H]+. Found: 316.1904 [M+H]+. IR vC=O: 1700, 1654 cm-1 (vs).
3d. Colorless liquid. (Following the procedure for the
preparation of 3a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (500 MHz, CDCl3) δ 7.47 (d, J = 7.2 Hz, 2H), 7.39 –
7.26 (m, 3H), 5.75 (s, 1H), 5.03 (s, 2H), 2.27 – 2.04 (m, 1H), 1.65
– 1.55 (m, 4H), 0.89 (t, J = 7.4 Hz, 6H). 13C NMR (126 MHz,
CDCl3) δ 170.26, 161.32, 149.30, 135.58, 129.23, 128.56,
128.06, 101.22, 47.01, 45.02, 24.71, 11.60. HRMS(ESI): calcd
for C17H21O3: 273.1491 [M+H]+. Found: 273.1438 [M+H]+. IR
vC=O: 1697, 1650 cm-1 (vs).
Conclusions
In summary, a series of LB-CO2/COS adducts are presented
as organocatalysts for [4+2] annulation of CO2/COS with
allenamides to directly construct functionalized 1,3-oxazine-
2,4-diones and 1,3-thiazine-2,4-diones under mild reaction
conditions. Notably, this reaction features high selectivity, high
atom economy, smooth scalability and easy derivation of
important structures.
3e. Colorless liquid. (Following the procedure for the
preparation of 3a, eluent: petroleum ether / ethyl acetate =
1
5:1) H NMR (500 MHz, CDCl3) δ 7.47 (d, J = 7.1 Hz, 2H), 7.31
Experimental
General information
(dd, J = 16.1, 9.0 Hz, 3H), 5.73 (s, 1H), 5.03 (s, 2H), 2.26 (p, J =
6.6 Hz, 1H), 1.95 (dq, J = 13.3, 6.5 Hz, 1H), 1.15 (d, J = 6.9 Hz,
3H), 0.95 – 0.89 (m, 6H). 13C NMR (126 MHz, CDCl3) δ 171.40,
161.42, 149.17, 135.72, 129.23, 128.54, 128.04, 100.33, 44.99,
44.10, 30.50, 20.84, 18.88, 13.81. HRMS(ESI): calcd for
Unless otherwise stated, all manipulations were performed using
standard Schlenk techniques under a dry argon atmosphere. NHC-
CO2 adducts,11 NHO-CO2 adducts,8a, 8e THPE-CO2 adducts8g,8i and 2,3-
allenamides12 were prepared according to a reported procedure.
COS and CO2 (>99%), and all other reagents were used without
further purification.
C16H20NO3: 274.1443 [M+H]+. Found: 274.1435 [M+H]+. IR vC=O
:
1700, 1650 cm-1 (vs).
3f. White solid. (Following the procedure for the preparation
1
of 3a, eluent: petroleum ether / ethyl acetate = 5:1) H NMR
General procedure for LB-CO2 adducts catalyzed [4+2] annulation
of CO2 with allenamides.
(500 MHz, CDCl3) δ 7.48 (d, J = 7.2 Hz, 2H), 7.37 – 7.25 (m, 3H),
5.72 (s, 1H), 5.02 (s, 2H), 2.29 (t, J = 9.0 Hz, 1H), 1.93 (d, J = 7.8
Hz, 2H), 1.83 (d, J = 5.9 Hz, 2H), 1.72 (d, J = 12.5 Hz, 1H), 1.40 –
1.24 (m, 5H). 13C NMR (126 MHz, CDCl3) δ 171.75, 161.66,
149.23, 135.73, 129.33, 128.53, 128.06, 98.72, 44.93, 41.26,
29.57, 25.52. HRMS(ESI): calcd for C17H20NO3: 286.1443
[M+H]+. Found: 286.1438 [M+H]+. IR vC=O: 1700, 1658 cm-1 (vs).
3g. White solid. (Following the procedure for the
preparation of 3a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (500 MHz, CDCl3) δ 7.40 (d, J = 7.1 Hz, 2H), 7.27 –
7.20 (m, 3H), 5.70 (s, 1H), 4.95 (s, 2H), 2.70 (p, J = 7.8 Hz, 1H),
1.96 – 1.80 (m, 2H), 1.69 (s, 2H), 1.59 (d, J = 11.1 Hz, 4H). 13C
NMR (126 MHz, CDCl3) δ 171.10, 161.52, 149.25, 135.73,
129.32, 128.53, 128.06, 99.06, 44.93, 42.73, 30.40, 25.41.
HRMS(ESI): calcd for C16H18NO3: 272.1287 [M+H]+. Found:
272.1283 [M+H]+. IR vC=O: 1697, 1654 cm-1 (vs).
In a glove box, a 10 mL Schlenk flask equipped with a
magnetic stir bar was charged with N-benzyl-4-methylpenta-
2,3-alkenamide 2a (0.5 mmol), LB-CO2 adduct 1k (5.0 mol%),
1,2,4,5-tetramethylbenzene (0.5 mmol) and DMSO (0.5 mL),
successively. The flask was then evacuated and filled with CO2
with a balloon and the reaction was stirred at 60 oC for 2
hours. After the reaction was completed as monitored by TLC
and quenched with 5 mL of H2O, extracted with DCM (10 mL ×
3), washed with brine, and dried over anhydrous Na2SO4. After
filtration and evaporation, the residue was purified by column
chromatography (eluent: petroleum ether / ethyl acetate =
1
5:1) to give the product 3a. White solid. H NMR (500 MHz,
CDCl3) δ 7.48 (d, J = 7.2 Hz, 2H), 7.41 – 7.20 (m, 3H), 5.75 (s,
1H), 5.03 (s, 2H), 2.79 – 2.48 (m, 1H), 1.21 (d, J = 6.9 Hz, 6H).
13C NMR (126 MHz, CDCl3) δ 172.55, 161.57, 149.16, 135.70,
129.32, 128.54, 128.07, 98.57, 44.95, 31.95, 19.27.
3b. Colorless liquid. (Following the procedure for the
preparation of 3a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (500 MHz, CDCl3) δ 7.48 (d, J = 7.1 Hz, 2H), 7.38 –
7.27 (m, 3H), 5.75 (s, 1H), 5.10 – 4.99 (m, 2H), 2.41 (h, J = 6.8
3h. White solid. (Following the procedure for the
preparation of 3a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (500 MHz, CDCl3) δ 7.44 (d, J = 7.0 Hz, 2H), 7.38 –
7.20 (m, 8H), 5.72 (s, 1H), 5.01 – 4.91 (m, 2H), 3.74 (q, J = 7.1
Hz, 1H), 1.53 (d, J = 7.2 Hz, 3H). 13C NMR (126 MHz, CDCl3) δ
4 | J. Name., 2012, 00, 1-3
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170.35, 161.42, 148.93, 139.27, 135.68, 129.38, 129.04, 1H), 1.67 – 1.46 (m, 2H), 1.21 (d, J = 6.9 Hz, 3H), 0.91 (t, J = 7.4
View Article Online
13
DOI: 10.1039/C9OB02398D
128.58, 128.14, 127.90, 127.73, 100.20, 45.05, 43.08, 18.02.
Hz, 3H). C NMR (101 MHz, CDCl3) δ 165.2, 163.8, 159.0,
3i. Colorless liquid. (Following the procedure for the 136.2, 129.3, 128.5, 127.9, 114.2, 44.7, 42.8, 28.9, 19.7, 11.7.
preparation of 3a, eluent: petroleum ether / ethyl acetate = HRMS(ESI): calcd for C15H17NO2S: 276.1053 [M+H]+. Found:
1
5:1) H NMR (500 MHz, CDCl3) δ 5.73 (s, 1H), 3.97 – 3.78 (m, 276.1051 [M+H]+. IR vC=O: 1684, 1652 cm-1 (vs).
2H), 2.76 – 2.55 (m, 1H), 1.69 – 1.57 (m, 2H), 1.43 – 1.31 (m,
4c. Yellow liquid. (Following the procedure for the
2H), 1.24 (d, J = 6.9 Hz, 6H), 0.95 (t, J = 7.3 Hz, 3H). 13C NMR preparation of 4a, eluent: petroleum ether / ethyl acetate =
1
(126 MHz, CDCl3) δ 172.36, 161.68, 149.13, 98.50, 41.74, 5:1) H NMR (400 MHz, CDCl3) δ 7.45 (d, J = 6.9 Hz, 2H), 7.28
31.90, 29.38, 20.00, 19.26, 13.67.
(dt, J = 8.4, 6.8 Hz, 3H), 6.35 (s, 1H), 5.17 (s, 2H), 2.61 – 2.40
3j. Colorless liquid. (Following the procedure for the (m, 1H), 1.61 – 1.40 (m, 2H), 1.37 – 1.13 (m, 12H), 0.87 (t, J =
preparation of 3a, eluent: petroleum ether / ethyl acetate = 6.6 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 165.2, 163.8, 159.3,
5:1) 1H NMR (500 MHz, CDCl3) δ 5.69 (s, 1H), 5.06 (dt, J = 13.8, 136.2, 129.3, 128.5, 127.8, 114.1, 44.6, 41.3, 35.9, 31.6, 29.1,
6.9 Hz, 1H), 2.63 (dt, J = 13.8, 6.9 Hz, 1H), 1.45 (d, J = 6.9 Hz, 27.1,
22.6,
20.2,
14.1.
HRMS(ESI):
calcd
for
6H), 1.23 (d, J = 6.9 Hz, 6H). 13C NMR (126 MHz, CDCl3) δ C19H17NO2S:324.1053 [M+H]+. Found: 324.1053 [M+H]+. IR
172.31, 162.15, 148.11, 98.70, 45.92, 31.77, 19.23, 18.87. vC=O: 1688, 1651 cm-1 (vs).
HRMS(ESI): calcd for C10H16NO3: 198.1130 [M+H]+. Found:
198.1121 [M+H]+. IR vC=O: 1700, 1659 cm-1 (vs).
4d. Yellow liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
3k. White solid. (Following the procedure for the 5:1) 1H NMR (400 MHz, CDCl3) δ 7.45 (d, J = 6.9 Hz, 2H), 7.38 –
preparation of 3a, eluent: petroleum ether / ethyl acetate = 7.18 (m, 3H), 6.35 (s, 1H), 5.18 (s, 2H), 2.32 – 2.12 (m, 1H), 1.73
5:1) 1H NMR (400 MHz, CDCl3) δ 5.69 (s, 1H), 4.65 (tt, J = 12.2, – 1.40 (m, 4H), 0.89 (t, J = 7.4 Hz, 6H). 13C NMR (101 MHz,
3.8 Hz, 1H), 2.67 – 2.58 (m, 1H), 2.29 (qd, J = 12.4, 3.4 Hz, 2H), CDCl3) δ 165.2, 163.5, 157.5, 136.2, 129.3, 128.5, 127.8, 115.3,
1.84 (dd, J = 13.4, 2.4 Hz, 2H), 1.68 – 1.61 (m, 3H), 1.42 – 1.26 50.9,
44.7,
27.2,
11.8.
HRMS(ESI):
calcd
for
(m, 3H), 1.23 (d, J = 6.9 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ C15H17NO2S:290.1209 [M+H]+. Found: 290.1213 [M+H]+. IR
172.26, 162.27, 148.33, 98.72, 54.02, 31.76, 28.26, 26.09, vC=O: 1689, 1651 cm-1 (vs).
25.05, 19.24. HRMS(ESI): calcd for C13H20NO3: 238.1443
4e. Colorless liquid. (Following the procedure for the
[M+H]+. Found: 328.1435 [M+H]+. IR vC=O: 1698, 1658 cm-1 (vs). preparation of 4a, eluent: petroleum ether / ethyl acetate =
3l. Colorless liquid. (Following the procedure for the 5:1) 1H NMR (400 MHz, CDCl3) δ 7.36 (d, J = 7.0 Hz, 2H), 7.29 –
preparation of 3a, eluent: petroleum ether / ethyl acetate = 7.09 (m, 3H), 6.25 (s, 1H), 5.08 (s, 2H), 2.30 – 2.04 (m, 1H), 1.73
5:1) 1H NMR (500 MHz, CDCl3) δ 5.79 (s, 1H), 4.65 (s, 2H), 2.26 – 1.57 (m, 1H), 1.09 (d, J = 7.0 Hz, 3H), 0.84 (t, J = 6.6 Hz, 6H).
(s, 1H), 2.21 (dd, J = 13.6, 6.5 Hz, 1H), 1.71 – 1.56 (, 4H), 0.92 (t, 13C NMR (101 MHz, CDCl3) δ 165.1, 163.7, 158.8, 136.2, 129.2,
J = 7.5 Hz, 6H). 13C NMR (126 MHz, CDCl3) δ 170.66, 160.21, 128.4, 127. 8, 114.5, 48.1, 44.6, 32.6, 21.1, 19.5, 17.0.
148.41, 101.01, 76.84, 71.78, 47.08, 31.01, 24.72, 11.56. HRMS(ESI): calcd for C12H15NO2S:290.1209 [M+H]+. Found:
HRMS(ESI): calcd for C12H16NO3: 222.1130 [M+H]+. Found: 290.1207 [M+H]+. IR vC=O: 1686, 1647 cm-1 (vs).
222.1122 [M+H]+. IR vC=O: 1694, 1654 cm-1 (vs).
4f. Yellow liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (400 MHz, CDCl3) δ 7.50 (d, J = 6.8 Hz, 2H), 7.41 –
7.26 (m, 3H), 6.41 (s, 1H), 5.23 (s, 2H), 2.37 (m, J = 11.0 Hz, 1H),
1.91 (m, J = 17.7, 9.9 Hz, 4H), 1.77 (d, J = 12.6 Hz, 1H), 1.49 –
1.17 (m, 5H). 13C NMR (101 MHz, CDCl3) δ 165.2, 163.9, 158.9,
136.2, 129.2, 128.4, 127.8, 113.4, 44.9, 44.5, 32.1, 25.9, 25.4.
HRMS(ESI): calcd for C17H19NO2S: 302.1209 [M+H]+. Found:
302.1211 [M+H]+. IR vC=O: 1683, 1651 cm-1 (vs).
4g. White solid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (500 MHz, CDCl3) δ 7.35 (d, J = 7.2 Hz, 2H), 7.25 –
7.11 (m, 3H), 6.29 (s, 1H), 5.08 (s, 2H), 2.78 – 2.65 (m, 1H), 1.97
– 1.85 (m, 2H), 1.74 – 1.62 (m, 2H), 1.62 – 1.46 (m, 4H). 13C
NMR (126 MHz, CDCl3) δ 164.2, 162.8, 156.9, 135.3, 128.2,
127.4, 126.8, 112.6, 45.1, 43. 6, 31.3, 24.2. HRMS(ESI): calcd
for C16H17NO2S:288.1053 [M+H]+. Found: 288.1052 [M+H]+. IR
vC=O: 1686, 1651 cm-1 (vs).
General procedure for LB-COS adducts catalyzed [4+2] annulation
of COS with allenamides.
In a glove box, a 20 mL autoclave containing a stirring bar
was charged with N-benzyl-4-methylpenta-2,3-alkenamide 2a
(0.5 mmol), LB-COS adduct S1j (5.0 mol%), 1,2,4,5-
tetramethylbenzene (0.5 mmol), and acetonitrile (0.5 mL),
successively. Then the autoclave was charged with COS (1.0
MPa). After stirring at 60 °C for 12 hours, the reaction were
stopped by cooling the autoclave in an ice bath, and unreacted
carbonyl sulfide was slowly vented. The crude reaction mixture
was purified by column chromatography (eluent: petroleum
1
ether / ethyl acetate = 5:1) to obtain 4a. Colorless liquid. H
NMR (500 MHz, CDCl3) δ 7.44 (d, J = 7.0 Hz, 2H), 7.28 (dt, J =
16.6, 4.7 Hz, 3H), 6.37 (s, 1H), 5.18 (s, 2H), 2.79 – 2.56 (m, 1H),
1.24 (d, J = 6.9 Hz, 6H). 13C NMR (126 MHz, CDCl3) δ 165.2,
164.0, 160.0, 136.3, 129.3, 128.6, 127.9, 113.4, 44.7, 35.4,
21.8. HRMS(ESI): calcd for C14H15NO2S: 262.0896 [M+H]+.
Found: 262.0897 [M+H]+. IR vC=O: 1689, 1651 cm-1 (vs).
4b. Colorless liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (400 MHz, CDCl3) δ 7.51 – 7.39 (m, 2H), 7.28 (dq, J
= 14.2, 7.0 Hz, 3H), 6.35 (s, 1H), 5.17 (s, 2H), 2.54 – 2.37 (m,
4h. White solid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (400 MHz, CDCl3) δ 7.42 (d, J = 7.1 Hz, 2H), 7.35 –
7.13 (m, 8H), 6.43 (s, 1H), 5.12 (s, 2H), 3.79 (q, J = 7.0 Hz, 1H),
1.55 (d, J = 7.2 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 164.8,
163.7, 157.6, 140.2, 136.1, 129.2, 129.0, 128.4, 127.9, 127.8,
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J. Name., 2013, 00, 1-3 | 5
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127.5, 114.4, 45.5, 44.6, 19.6. HRMS(ESI): calcd for 5:3) 1H NMR (500 MHz, CDCl3) δ 7.77 (d, J = 8.3 Hz, 2H), 7.37 (t,
View Article Online
C19H25NO2S:332.1679 [M+H]+. Found: 332.1680 [M+H]+. IR J = 7.3 Hz, 2H), 7.32 (dd, J = 7.5, 3.8 Hz, 3H), 7.24 – 7.20 (m,
DOI: 10.1039/C9OB02398D
vC=O: 1682, 1651 cm-1 (vs).
2H), 6.45 (s, 2H), 5.42 (s, 1H), 3.87 (q, J = 7.0 Hz, 3H), 2.44 (s,
4i. Yellow liquid. (Following the procedure for the 2H), 1.63 (d, J = 7.1 Hz, 3H). 13C NMR (126 MHz, CDCl3) δ 164.1,
preparation of 4a, eluent: petroleum ether / ethyl acetate = 162.2, 158.8, 145.5, 139.9, 136.2, 130.0, 129.3, 128.7, 128.3,
1
5:1) H NMR (500 MHz, CDCl3) δ 6.35 (s, 1H), 4.07 – 3.85 (m, 127.6, 113.9, 60.4, 45.8, 21.8, 19.8. HRMS(ESI): calcd for
2H), 2.78 – 2.62 (m, 1H), 1.59 (dt, J = 15.3, 7.6 Hz, 2H), 1.36 C20H19NO4S2: 402.0828 [M+H]+. Found: 402.0847 [M+H]+. IR
(dq, J = 14.8, 7.4 Hz, 2H), 1.26 (d, J = 6.9 Hz, 6H), 0.94 (t, J = 7.4 vC=O: 1698, 1658 cm-1 (vs).
Hz, 3H). 13C NMR (126 MHz, CDCl3) δ 165.0, 164.1, 159.7,
113.3, 41.8, 35.4, 29.8, 29.8, 21.8, 20.3, 13.8. HRMS(ESI): calcd
for C11H17NO2S: 228.1053 [M+H]+. Found: 228.1051 [M+H]+. IR
vC=O: 1689, 1655 cm-1 (vs).
Crystallography
Supplementary crystallographic data was deposited at the
Cambridge Crystallographic Data Centre (CCDC) under the numbers
CCDC 1859584 (4h) and can be obtained free of charge from via
www.ccdc.cam.ac.uk/data_request.cif.
4j. Colorless liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
1
5:1) H NMR (400 MHz, CDCl3) δ 6.22 (d, J = 0.7 Hz, 1H), 5.19
(hept, J = 6.9 Hz, 1H), 2.69 – 2.48 (m, 1H), 1.38 (d, J = 6.9 Hz,
6H), 1.17 (d, J = 6.9 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 164.9,
164.6, 159.7, 113.6, 77.5, 77.2, 76.8, 47.3, 35.1, 21.6, 19.4.
HRMS(ESI): calcd for C10H15NO2S: 214.0896 [M+H]+. Found:
214.0898 [M+H]+. IR vC=O: 1688, 1657 cm-1 (vs).
Conflicts of interest
There are no conflicts to declare.
4k. White solid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (400 MHz, CDCl3) δ 6.30 (s, 1H), 4.85 (tt, J = 12.2,
3.7 Hz, 1H), 2.67 (hept, J = 6.8 Hz, 1H), 2.33 (qd, J = 12.3, 3.3
Hz, 2H), 1.87 – 1.78 (m, 2H), 1.63 (dd, J = 7.7, 3.6 Hz, 3H), 1.45
– 1.27 (m, 3H), 1.25 (d, J = 6.9 Hz, 6H). 13C NMR (101 MHz,
CDCl3) δ 165.1, 164.8, 159.6, 113.6, 55.7, 35.1, 28.7, 26.4, 25.3,
21.6. HRMS(ESI): calcd for C13H19NO2S: 254.1209 [M+H]+.
Found: 254.1213 [M+H]+. IR vC=O: 1687, 1651 cm-1 (vs).
Acknowledgements
This work is supported by National Natural Science Foundation
of China (Grant No. 91856108), the Fundamental Research
Funds for the Central Universities (DUT18LK55) and the
Program for Changjiang Scholars and Innovative Research
Team in University (IRT-17R14).
4l. Yellow liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:1) 1H NMR (400 MHz, CDCl3) δ 6.39 (s, 1H), 4.76 (d, J = 2.3 Hz,
2H), 2.40 – 2.14 (m, 2H), 1.73 – 1.61 (m, 2H), 1.55 (tt, J = 14.5,
7.4 Hz, 2H), 0.93 (t, J = 7.4 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ
164.3, 162.4, 157.9, 115.0, 77.5, 71.1, 51.0, 30.5, 27.2, 27.0,
11.7. HRMS(ESI): calcd for C12H15NO2S: 238.0896 [M+H]+.
Found: 235.0895 [M+H]+. IR vC=O: 1695, 1651 cm-1 (vs).
4m. Yellow liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:3) 1H NMR (500 MHz, CDCl3) δ 7.77 (d, J = 8.3 Hz, 2H), 7.44 –
7.28 (m, 5H), 7.24 – 7.14 (m, 2H), 6.34 (s, 1H), 5.43 (s, 2H), 3.78
(s, 2H), 2.44 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 164.0, 161.9,
153.7, 145.5, 136.3, 134.0, 130.0, 129.3, 129.3, 128.7, 128.3,
115.4, 60.4, 42.2, 21.9. HRMS(ESI): calcd for C19H17NO4S2:
388.0672 [M+H]+. Found: 388.0667 [M+H]+. IR vC=O: 1698, 1656
cm-1 (vs).
4n. Yellow liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
5:3) 1H NMR (500 MHz, CDCl3) δ 7.79 (d, J = 8.3 Hz, 2H), 7.51 –
7.28 (m, 8H), 7.25 – 7.13 (m, 4H), 6.20 (d, J = 1.2 Hz, 1H), 5.44
(s, 2H), 5.15 (s, 1H), 2.44 (s, 3H). 13C NMR (126 MHz, CDCl3) δ
164.0, 161.9, 156.7, 145.4, 137.7, 136.1, 129.9, 129.1, 128.6,
128.2, 117.1, 60.4, 57.0, 21.8. HRMS(ESI): calcd for
C25H21NO4S2: 464.0985 [M+H]+. Found: 464.0983 [M+H]+. IR
vC=O: 1698, 1662 cm-1 (vs).
Notes and references
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4o. Yellow liquid. (Following the procedure for the
preparation of 4a, eluent: petroleum ether / ethyl acetate =
6 | J. Name., 2012, 00, 1-3
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Organic & Biomolecular Chemistry
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ARTICLE
Journal Name
View Article Online
DOI: 10.1039/C9OB02398D
Access to 1,3-Oxazine-2,4-diones/1,3-thiazine-2,4-diones via Organocatalytic
CO2/COS Incorporation into Allenamides
Hui Zhou,* Rui Wang, Hui Zhang, Wei Chen and Xiao-Bing Lu
Lewis base-CO2/COS adducts were firstly studied as organocatalysts for [4+2] annulation of CO2/COS with allenamides to selectively
synthesize 1,3-Oxazine-2,4-diones/1,3-thiazine-2,4-diones.
8 | J. Name., 2012, 00, 1-3
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