Synthesis of Thio-/Selenopyrrolines via SnCl4-Catalyzed (3+2)-Cycloadditions of Donor-Acceptor Cyclopropanes with Thio-/Selenocyanates

Article abstract of DOI:10.1002/ejoc.202100846

A straightforward protocol has been developed to access thio-/selenopyrrolines through a (3+2)-cycloaddition of aryl thio-/selenocyanates with donor-acceptor cyclopropanes (DACs) in the presence of SnCl₄ as a Lewis acid catalyst. Further, good chemoselectivity was observed when DACs were treated with 3-cyano phenyl thiocyanate. These results suggest that thiocyanate is more reactive than nitrile moiety in such (3+2)-cycloaddition reactions.

Full text of DOI:10.1002/ejoc.202100846

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Synthesis of Thio-/Selenopyrrolines via SnCl4-Catalyzed (3
+2)-Cycloadditions of Donor-Acceptor Cyclopropanes with
Thio-/Selenocyanates
Prasoon Raj Singh,[a] Pratibha Kalaramna,[a] Shamsad Ali,[a] and Avijit Goswami*[a]
A straightforward protocol has been developed to access thio-/
selenopyrrolines through a (3+2)-cycloaddition of aryl thio-/
selenocyanates with donor-acceptor cyclopropanes (DACs) in
the presence of SnCl4 as a Lewis acid catalyst. Further, good
chemoselectivity was observed when DACs were treated with
3-cyano phenyl thiocyanate. These results suggest that thiocya-
nate is more reactive than nitrile moiety in such (3+2)-
cycloaddition reactions.
Introduction
During the past several decades, nitrogen-containing molecules
are an important class of heterocyclic compounds that displays
interesting applications in the field of medicinal chemistry.[1]
Among the known nitrogen-containing heterocycles, pyrrolines
are one of the most important classes of azaheterocycles found
in a variety of natural products and bioactive molecules.[2]
Furthermore, the heteroatom substituted pyrrolines have ex-
hibited a number of interesting chemical and biological
properties.[3] Literature survey has revealed that among numer-
ous protocols to access pyrroline derivatives,[2a] (3+2)-cyclo-
addition of donor-acceptor cyclopropanes (DACs) are few.[4]
Over the past decades, DACs are known as one of the most
strained rings, prompted chemists to explore their synthetic
potential due to their remarkable and unique reactivity. The
reactivity may be attributed due to both inherent strain and the
push-pull effect of substituents.[5] A wide range of cyclo-
additions with various 1,2-, 1,3-, 1,4-, dipoles including dienes,[6]
alkynes,[7] imines,[8] carbonyls,[9] have been reported using DACs
as a reactive partner; however, any heteroatom (especially
chalcogen) substituted pyrrolines has not been reported yet via
mentioned cycloaddition protocol.
Scheme 1. (3+2)-Cycloadditions of donor-acceptor cyclopropanes with
nitriles.
olactone-fused DÀ A cyclopropanes with nitriles to obtain γ-
butyrolactone-fused 1-pyrrolines (Scheme 1).[14] However, all of
these aforementioned methods are limited to alkyl or aryl
nitriles. Recently, Werz et. al. investigated Yb(OTf)3-catalyzed (3
+2) cycloaddition of DACs with ammonium thio-/selenocyanate
to achieve dihydrothio-/selenophenes.[15] Later, the same group
delineated the synthesis of pyrrolidine-2-thiones allowing the
treatment of D-A cyclopropanes with 1-methylimidazolium
thiocyanate.[16]
Herein, we report a thio-/selenocyanate source dependent
(3+2)-cycloaddition reactions protocol for the synthesis of
thio-/selenopyrrolines in the presence of SnCl4 as a Lewis acid
catalyst.
Encouraged by our previous work related to the synthesis of
sulfur-/selenium-containing heterocycles,[10] we currently devote
our attention for construction of the thiopyrrolines via cyclo-
addition strategy using DACs as one of the coupling partners.
Pioneer work in this field includes the SnCl4-promoted (3+2)-
cycloaddition reaction between DACs and nitriles reported by
Trushkov’s group[11] and Srinivasan’s group.[12] In 2014, Wang
et al. disclosed the TfOH-catalyzed (3+2)-cycloaddition reaction
of DACs with nitriles (Scheme 1).[13] Later in 2019, Srinivasan and Results and Discussion
co-workers have delineated the (3+2)-annulation of γ-butyr-
At the onset, the exploration and optimization of (3+2)-
cycloaddition reaction of donor-acceptor cyclopropane 1a with
phenyl selenocyanate 2a was carried out. An array of Lewis
acids involving Ti, Cu, Fe, Yb, In and Sn based complexes were
employed in this survey, and the results are summarized in
Table 1.
[a] P. R. Singh, P. Kalaramna, S. Ali, Dr. A. Goswami
Department of Chemistry, SS Bhatnagar Block, Main Campus, Indian
Institute of Technology Ropar,
Rupnagar, Punjab 140001, India
E-mail: agoswami@iitrpr.ac.in
Supporting information for this article is available on the WWW under
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Table 1. Optimization of the reaction conditions.a
°
Entry
Lewis acid
[equiv.]
Solvent
T C
Time
[h]
Yield
3aa [%])b
°
1
2
3
4
5
6
7
8
TiCl4 (1)
Yb(OTf)3 (1)
FeCl3 (1)
Cu(OTf)2 (1)
InCl3 (1)
TfOH (1)
TfOH (1)
TfOH (1)
AlCl3 (1)
SnCl4 (1)
SnCl4 (1)
SnCl4 (1)
SnCl4 (1)
SnCl4 (1)
SnCl4 (0.3)
SnCl4 (1.5)
TMSOTf (1)
BF3.OEt2 (1)
DCM
À 5 C to rt
24
24
24
24
24
5
5
4
6
4
5
5
5
5
2
4
5
5
–
–
–
–
°
1,2-DCE
1,2-DCE
1,2-DCE
1,2-DCE
DCM
1,2-DCE
1,2-DCE
1,2-DCE
1,2-DCE
1,2-DCE
DCM
40 C
°
40 C
°
40 C
°
40 C
–
rt
rt
trace
42
37
51
66
54
59
62
–
°
40 C
°
9
40 C
°
10
11
12
13
14
15
16
17
18
40 C
rt
°
40 C
°
CHCl3
40 C
°
Toluene
1,2-DCE
1,2-DCE
MeNO2
DCM
60 C
°
50 C
87
65
–
°
40 C
Scheme 2. SnCl4-catalyzed synthesis of various selenopyrroline derivatives 3
via (3+2)-cycloadditions.[a] [a] Reaction Conditions: 1 (0.30 mmol), 2
rt
rt
–
°
(0.36 mmol), SnCl4 (0.01 mL, 30 mol%), 1,2-DCE (2.0 mL), 50 C, inert con-
ditions, 2–3 h.
[a] Optimized reaction conditions for 3aa: 1a (78.6 mg, 0.30 mmol), 2a
°
(65.5 mg, 0.36 mmol), SnCl4 (0.01 mL, 0.3 eq.), 1,2-DCE (2.0 mL), 50 C, inert
atmosphere, 2 h. [b] Isolated yield.
The reaction of α-carbonyl selenocyanate 2i with cyclo-
propane 1a furnished selenopyrroline 3ai in 81% yield. It is
noteworthy that the yields were higher for aromatic selenocya-
nates having electron-donating substituents in the para-posi-
tion as compared to those with electron-withdrawing substitu-
ents in the position. (Scheme 2).
The cycloaddition was initially investigated with Ti, Fe, Yb,
and In-based Lewis acids; however, none of them could deliver
the expected product 3aa (Table 1, entries 1–5). Taking the lead
from the previous work,[12] the cycloaddition was performed in
the presence of TfOH in DCM at room temperature. The
cycloaddition resulted in the formation of product in trace
amount (Table 1, entry 6). Further tuning the reaction condi-
tions, the cycloaddition increased the yield up to 42% (Table 1,
entries 7–8). Unfortunately, the reaction, even with the replace-
ment of TfOH with AlCl3, was not much effective (Table 1,
entry 9). In order to achieve the product with a higher yield,
cycloaddition was further explored in the presence of SnCl4 as a
Lewis acid (Table 1, entries 10–15). To our delight, the cyclo-
addition furnished the product with 66% yield using 1 eq. of
Encouraged by the results, the scope of the protocol was
also explored for the tin (IV)-catalyzed (3+2)-cycloaddition of
DACs 1 and alkyl/arylthiocyanates 4 for the synthesis of
thiopyrroline derivatives 5, and the results are shown in
Scheme 3. At first, a number of DACs were examined. Cyclo-
propane, bears a substituent such as a methoxy at the aryl ring,
was an effective coupling partner, affording the corresponding
product 5ea in 89% yield. On the other hand, DACs bearing
nitro group at aryl ring offered the desired cycloadduct 5fa
with a relatively lower yield. Next, we focused on investigating
the scope of thiocyanates 4 with cyclopropane 1a. The reaction
proceeded smoothly to provide thiopyrrolines 5ab and 5ac in
88% and 82% yields for thiocyanates 4b and 4c bearing
methyl and methoxy group at para-position, respectively. Aryl
thiocyanates, containing electron-withdrawing substituents at
the para-position, including nitro and acetyl, were well
tolerated, and the reaction provided compounds 5ae and 5ad
in 76% and 81% yields, respectively. Treating methyl thiocya-
nate 4f with cyclopropane 1a, the corresponding cycloadduct
5af was obtained in 91% yield. The cycloaddition also
proceeded smoothly with benzyl thiocyanate, and the corre-
sponding cycloadduct 5ag was produced in 93% yield.
°
SnCl4 in DCE at 40 C for 4 h. Further optimization towards the
other reaction parameters like the amount of catalyst, solvent,
and temperature successfully delivered the product in 87%
yield (Table 1, entry 15). Other commercially available Lewis
acids, like TMSOTf, and BF3.OEt2, failed to catalyze the trans-
formation (Table 1, entries 17–18).
Employing the optimized reaction conditions, a plethora of
selenopyrrolines could be accessed exclusively (Scheme 2).
Electron-deficient (2b, 2e), and electron-rich (2a, 2g, 2h) aryl
selenocyanates reacted to deliver the selenopyrroline cyclo-
adducts in good to excellent yields. Additionally, substitutions
at ortho-positions of the aryl selenocyanates were tolerated,
giving the cycloadduct 3ae and 3ag in yield of 74% and 89%
respectively. A broad range of functional groups was compat-
ible, including bromo (3ab), iodo (3ac), ester (3ad), nitro (3ae),
and tert-butyl (3ah) groups.
In order to investigate the chemoselectivity, we embarked
on probing the reaction of thiocyanate 4h with cyclopropane
1a. To our delight, the reaction of 1 eq. of 1a with 1 eq. of 4h
delivered the separable mixture of cycloadducts 5ah and 5’’ah
in 76% and 12% yields, respectively. Increasing the equivalence
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After successfully constructing a range of heteroatom-
substituted pyrrolines, the gram-scale synthesis of selenopyrro-
line 3da was carried out using the optimized reaction
conditions. To our delight, the protocol was amenable to the
gram-scale synthesis of selenopyrroline 3da based on 5 mmol
of cyclopropane 1a with 6 mmol of phenyl selenocyanate 2a
(Scheme 5). Of note, the large-scale synthesis proceeded as
efficiently as the small-scale synthesis (Scheme 2), giving 3da in
90% yield (Scheme 5).
The versatility of the products as synthons was demon-
strated by the follow-up reaction of selenopyrroline 3aa. The
3H-pyrrole 6aa was obtained via dehydrogenation of seleno-
pyrroline 3aa. In this study, 2,3-dichloro-5,6-dicyanobenzoqui-
°
none (DDQ) was employed as an oxidant in benzene at 80 C
(Scheme 6).
Conclusion
Scheme 3. Synthesis of thiopyrroline derivatives 5 via SnCl4-catalyzed (3+2)-
cycloadditions.[a] [a] Reaction conditions: 1 (0.30 mmol), 4 (0.36 mmol), SnCl4
To conclude, we have documented a SnCl4-catalyzed (3+2)-
cycloaddition of DACs with thio-/selenocyanates for the syn-
thesis of thio-/selenopyrrolines under mild conditions. These
transformations are well tolerant to a wide range of functional
groups on aryl thio-/selenocyanate building blocks as well as D-
A cyclopropanes. The procedure provides a general, atom-
economical, and straightforward way to construct chalcogen
substituted azacycles in good to excellent yields. Further
utilization of thus obtained thio-/selenopyrrolines is underway.
°
(0.01 mL, 30 mol%), 1,2-DCE (2.0 mL), 50 C, inert conditions, 2–3 h.
of cyclopropane 1a to 2.5 eq., (3+2)-cycloaddition provided
the compounds 5ah, 5’ah and 5’’ah in 18%, 14% and 60%
yields, respectively. These results clearly indicate that thiocya-
nate moiety undergoes (3+2)-cycloaddition faster than the
nitrile group (Scheme 4).These results clearly indicate that the
aforementioned protocol has a remarkable practicable applic-
ability.
Experimental Section
General information: All the reactions were carried out under an
inert atmosphere using the Schlenk technique. All solvents were
dried and stored over molecular sieves under argon atmosphere.
All chemicals and reagents were purchased from commercial
suppliers and used without further purification. Thin-layer chroma-
tography (TLC) was performed using pre-coated plates purchased
from E. Merck (silica gel 60 PF254, 0.25 mm). Column chromatog-
raphy was performed using E. Merck silica gel 60 (100–200 mesh).
1H, 13C, and DPT-135 NMR spectra were recorded in CDCl3, on JEOL
JNM-ECS spectrometer at operating frequencies of 400 MHz (1H) or
100 MHz (13C) as indicated in the individual spectrum. Chemical
shifts (δ) are given in parts per million (ppm) relative to residual
solvent (chloroform, δ=7.26 for 1H and 77.16 for proton decoupled
13C NMR) and coupling constants (J) in Hz. Multiplicity is tabulated
as s for singlet, d for doublet, dd for doublet of doublet, t for triplet,
q for quartet, and m for multiplet. High-resolution mass spectra
(HRMS) were recorded using electron spray ionization (ESI) methods
on waters mass spectrometer (XEVO G2-XS QTOF). All cyclo-
propane-1,1-diester derivatives(1a–1h),[17] arylselenocyanates (2a–
Scheme 4. SnCl4-catalyzed chemoselectivity studies of DACs with 3-cyano
phenyl thiocyanate.[a] [a] Reaction Conditions: 1a (0.50–1.25 mmol), 4h
°
(0.50 mmol), SnCl4 (50 mol%), 1,2-DCE (2.0 mL), 50 C, inert conditions, 3 h.
[b] Isolated yield. [c] From NMR of crude mixture.
Scheme 5. Gram scale synthesis of 3da.[a][a]Reaction conditions: 1d (1.61 g,
5.00 mmol), 2a (1.09 g, 6.00 mmol) SnCl4 (0.175 mL, 50.0 mol%), 1,2-DCE
(5.0 mL),
Scheme 6. Preparation of seleno-substituted 3H-pyrrol 6aa.
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2i),[18] thiocyanates (4a–4h)[19] were synthesized according to the
reported literature procedures.
Diethyl 5-(3,4-dimethoxyphenyl)-2-(phenylselanyl)-4,5-dihydro-
3H-pyrrole-3,3-dicarboxylate (3da): Yield: 141 mg (93%); Yellow
1
viscous liquid; H NMR (400 MHz, CDCl3): δ 7.72–7.67 (m, 2H), 7.33–
General Procedure for the Synthesis of Seleno-/Thio Substituted
Pyrrolins 3 and 5: Cyclopropanediester (0.30 mmol, 1.0 eq.) and
seleno-/thiocyanate (0.36 mmol, 1.2 eq.) were dissolved in 1,2-DCE
7.29 (m, 3H), 6.78 (d, J=8.2 Hz, 1H), 6.73–6.68 (m, 2H), 5.14 (t, J=
7.6 Hz, 1H), 4.33 (q, J=7.2, 2H), 4.30–4.25 (m, 2H), 3.84 (s, 3H), 3.80
(s, 3H), 3.17 (dd, J=13.5, 7.5 Hz, 1H), 2.43 (dd, J=13.5, 7.7 Hz, 1H),
1.36 (t, J=7.1 Hz, 3H), 1.31 (t, J=7.1 Hz, 3H); 13C NMR (100 MHz,
CDCl3): δ 168.2, 167.6, 165.5, 148.9, 148.0, 135.4, 135.3, 129.2, 128.6,
128.0, 118.4, 110.9, 109.5, 75.1, 74.9, 62.7, 62.6, 55.9, 55.8, 42.2, 14.1,
°
under nitrogen atmosphere. The solution was stirred at 50 C for
two min and SnCl4 (30 mol%) was added. Reaction was continued
until TLC analysis showed complete consumption of cyclopropane.
The reaction mixture was passed through celite pad and concen-
trated in vacuo. Then the residue was purified by silica gel column
chromatography using ethyl acetate/hexane as eluent.
~
14.1; IR (neat) (v): 2988, 2941, 1750, 1520, 1384, 1229, 1136, 1080,
751 cmÀ 1; HRMS: m/z calculated for C24H28NO6Se [M+H]+ 506.1082,
found 506.1088.
Gram Scale Synthesis of 3da: Cyclopropanediester 1d (1.61 g,
5 mmol, 1.0 eq.) and selenocyanate 2a (1.10 g, 6 mmol, 1.2 eq.)
were dissolved in 1,2-DCE under nitrogen atmosphere. The solution
Diethyl
2-((4-bromophenyl)selanyl)-5-phenyl-4,5-dihydro-3H-
pyrrole-3,3-dicarboxylate (3ab): Yield: 122 mg (78%); Pale yellow
1
gum; H NMR (400 MHz, CDCl3): δ 7.53 (d, J=8.4 Hz, 2H), 7.43–7.39
°
was stirred at 50 C for two min and SnCl4 (0.175 mL, 50 mol%) was
(m, 2H), 7.38–7.33 (m, 1H), 7.29 (d, J=7.3 Hz, 1H), 7.22 (d, J=8.1 Hz,
1H), 7.14 (d, J=7.1 Hz, 2H), 5.16 (t, J=7.7 Hz, 1H), 4.30 (q, J=7.16,
2H), 4.25 (q, J=7.16, 2H), 3.15 (dd, J=13.6, 7.6 Hz, 1H), 2.42 (dd, J=
13.5, 7.9 Hz, 1H), 1.33 (t, J=7.0 Hz, 3H), 1.28 (t, J=7.1 Hz, 3H); 13C
NMR (100 MHz, CDCl3): δ 167.9, 167.6, 165.2, 142.4, 136.8, 133.5,
132.3, 128.6, 127.3, 126.4, 123.2, 75.5, 74.8, 62.8, 62.7, 42.2, 14.1,
added. Reaction was continued until TLC analysis showed complete
consumption of cyclopropane. The reaction mixture was passed
through celite pad and concentrated in vacuo. Then the residue
was purified by silica gel column chromatography using ethyl
acetate/hexane as eluent.
~
14.1; IR (neat) (v): 2983, 2923, 1740, 1584, 1458, 1376, 1250, 1175,
Synthesis of Diethyl 5-Phenyl-2-(phenylselanyl)-3H-pyrrole-3,3-
dicarboxylate (6aa): DDQ (25 mg, 0.1 mmol, 1 eq.) was added to
the solution of 3aa (44.6 mg, 0.1 mmol, 1 eq.) in benzene (3 mL)
and refluxed for 5.5 h. After full consumption of starting material,
the crude was purified by silica gel column chromatography using
ethyl acetate/hexane solution as eluent.
1063, 803 cmÀ 1; HRMS: m/z calculated for C22H23NO4SeBr [M+H]+
523.9976, found 523.9968.
Diethyl 5-((4-iodophenyl)selanyl)-2-phenyl-2H-pyrrole-4,4(3H)-di-
carboxylate (3ac): Yield: 138 mg (81%); Pale yellow gum; H NMR
1
(400 MHz, CDCl3): δ 7.63 (d, J=8.3 Hz, 2H), 7.41 (d, J=8.3 Hz, 2H),
7.32–7.28 (m, 2H), 7.26–7.23 (m, 1H), 7.20–7.14 (m, 2H), 5.18 (t, J=
7.7 Hz, 1H), 4.32 (q, J=7.2 Hz, 2H), 4.29–4.24 (m, 2H), 3.17 (dd, J=
13.6, 7.7 Hz, 1H), 2.44 (dd, J=13.5, 7.9 Hz, 1H), 1.35 (t, J=7.1 Hz,
3H), 1.30 (t, J=7.1 Hz, 3H).; 13C NMR (100 MHz, CDCl3): δ 167.9,
167.6, 165.1, 142.4, 138.3, 136.9, 128.6, 127.8, 127.3, 126.4, 95.0,
Characterization Data of Compounds
Diethyl 5-phenyl-2-(phenylselanyl)-4,5-dihydro-3H-pyrrole-3,3-di-
carboxylate (3aa): Yield: 116 mg (87%); Yellow viscous liquid; 1H
NMR (400 MHz, CDCl3): δ 7.75–7.66 (m, 2H), 7.35–7.31 (m, 3H), 7.28
(d, J=7.1 Hz, 2H), 7.25–7.22 (m, 1H), 7.18 (d, J=7.7 Hz, 2H), 5.20 (t,
J=7.7 Hz, 1H), 4.33 (q, J=7.16, 2H), 4.28 (q, J=7.12, 2H), 3.19 (dd,
J=13.5, 7.6 Hz, 1H), 2.45 (dd, J=13.0, 8.4 Hz, 1H), 1.37 (t, J=7.1 Hz,
3H), 1.31 (t, J=7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 168.1,
167.6, 165.6, 142.6, 135.3, 129.2, 128.6, 128.5, 128.0, 127.2, 126.4,
~
75.6, 74.9, 62.8, 62.7, 42.2, 14.1, 14.0.; IR (neat) (v): 2986, 2925, 1723,
1589, 1448, 1374, 1247, 1180, 1099, 984, 750 cmÀ 1; HRMS: m/z
calculated for C22H23NO4SeI [M+H]+ 571.9837, found 571.9839.
Diethyl
5-((4-(ethoxycarbonyl)phenyl)selanyl)-2-phenyl-2H-
pyrrole-4,4(3H)-dicarboxylate (3ad): Yield: 122.5 mg (79%); Yellow
viscous liquid; H NMR (400 MHz, CDCl3): δ 7.96 (d, J=8.3 Hz, 2H),
7.77 (d, J=8.2 Hz, 2H), 7.33–7.27 (m, 2H), 7.25–7.21 (m, 1H), 7.20–
7.16 (m, 2H), 5.21 (t, J=7.7 Hz, 1H), 4.38–4.27 (m, 6H), 3.18 (dd, J=
13.6, 7.6 Hz, 1H), 2.45 (dd, J=13.5, 8.0 Hz, 1H), 1.38–1.36 (m, 6H),
1.31 (t, J=7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 167.9, 167.5,
166.3, 164.7, 142.3, 134.7, 130.3, 130.0, 128.6, 127.3, 126.4, 75.7,
1
~
75.5, 74.9, 62.7, 62.6, 42.3, 14.1, 14.0; IR (neat) (v): 2981, 2931, 1729,
1587, 1444, 1250, 1186, 1094, 743, 686 cmÀ 1; HRMS: m/z calculated
for C22H24NO4Se [M+H]+ 446.0871, found 446.0864.
Diethyl 2-(phenylselanyl)-5-(p-tolyl)-4,5-dihydro-3H-pyrrole-3,3-
dicarboxylate (3ba): Yield: 122 mg (89%); Yellow solid (m.p.=99–
1
~
75.0, 62.8, 62.7, 61.2, 42.0, 14.4, 14.1, 14.0; IR (neat) (v): 2927, 2862,
°
102 C ); H NMR (400 MHz, CDCl3): δ 7.72–7.66 (m, 2H), 7.35–7.28
1723, 1590, 1458, 1266, 1176, 1103, 1013, 755 cmÀ 1; HRMS: m/z
calculated for C25H28NO6Se [M+H]+ 518.1082, found 518.1075.
(m, 3H), 7.11–7.05 (m, 4H), 5.15 (t, J=7.7 Hz, 1H), 4.32 (q, J=6.88,
2H), 4.27 (q, J=7.12, 2H), 3.16 (dd, J=13.5, 7.6 Hz, 1H), 2.43 (dd, J=
13.6, 8.0 Hz, 1H), 2.31 (s, 3H), 1.36 (t, J=7.1 Hz, 3H), 1.31 (t, J=
7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 168.1, 167.7, 165.3, 139.7,
136.8, 135.3, 129.2, 129.1, 128.6, 128.1, 126.4, 75.3, 74.9, 62.7, 62.6,
Diethyl 5-((2-nitrophenyl)selanyl)-2-phenyl-2H-pyrrole-4,4(3H)-di-
carboxylate (3ae): Yield: 108 mg (74%); Yellow viscous liquid; 1H
NMR (400 MHz, CDCl3): δ 8.25 (d, J=6.9 Hz, 1H), 8.15 (d, J=6.7 Hz,
1H), 7.51–7.46 (m, 1H), 7.40–7.32 (m, 3H), 7.29–7.27 (m, 3H), 5.36 (t,
J=7.8 Hz, 1H), 4.36–4.27 (m, 4H), 3.24 (dd, J=13.6, 7.6 Hz, 1H), 2.48
(dd, J=13.6, 8.0 Hz, 1H), 1.34–1.29 (m, 6H); 13C NMR
(100 MHz,CDCl3): δ 168.1, 167.4, 165.1, 148.2, 141.7, 134.6, 133.5,
129.7, 128.8, 127.7, 127.6, 126.6, 125.5, 76.6, 75.7, 63.1, 62.9, 41.8,
~
42.4, 21.2, 14.1, 14.0; IR (neat) (v): 3089, 2981, 2919, 1706, 1428,
1251, 1065, 720 cmÀ 1;HRMS: m/z calculated for C23H26NO4Se [M+
H]+ 460.1027, found 460.1021.
Diethyl 5-mesityl-2-(phenylselanyl)-4,5-dihydro-3H-pyrrole-3,3-di-
carboxylate (3ca): Yield: 134 mg (92%); Yellow viscous liquid; 1H
NMR (400 MHz, CDCl3): δ 7.61 (d, J=8.5 Hz, 2H), 7.34 (d, J=8.5 Hz,
2H), 7.25–7.22 (m, 1H), 7.19–7.15 (m, 2H), 5.20 (t, J=7.7 Hz, 1H),
4.32 (q, J=7.2 Hz, 2H), 4.27 (q, J=6.7 Hz, 2H), 3.17 (dd, J=13.5,
7.6 Hz, 1H), 2.44 (dd, J=13.6, 7.8 Hz, 1H), 1.36 (t, J=7.1 Hz, 3H),
1.32–1.28 (m, 12H); 13C NMR (100 MHz, CDCl3): δ 168.2, 167.6, 162.6,
136.7, 136.5, 136.0, 134.0, 130.1, 129.2, 128.8, 127.3, 74.6, 73.0, 62.6,
~
14.1, 14.0; IR (neat) (v): 2986, 2929, 1727, 1592, 1520, 1449, 1256,
1177, 1098, 1012, 734 cmÀ 1; HRMS: m/z calculated for C22H23N2O6Se
[M+H]+ 491.0721, found 491.0717.
Diethyl 5-phenyl-2-((4-(trifluoromethyl)phenyl)selanyl)-4,5-dihy-
dro-3H-pyrrole-3,3-dicarboxylate (3af): Yield: 105 mg (68%); Yel-
low solid (m.p.=80–82 C); H NMR (400 MHz, CDCl3): δ 7.63 (d, J=
8.3 Hz, 2H), 7.41 (d, J=8.3 Hz, 2H), 7.34–7.28 (m, 3H), 7.17–7.15 (m,
2H), 5.18 (t, J=7.7 Hz, 1H), 4.32 (q, J=7.16, 2H), 4.29–4.24 (m, 2H),
3.17 (dd, J=13.6, 7.6 Hz, 1H), 2.44 (dd, J=13.6, 7.9 Hz, 1H), 1.35 (t,
1
°
~
62.6, 40.1, 20.9, 20.8, 14.2, 14.2; IR (neat) (v): 3056, 2932, 1733, 1566,
1450, 1261, 1093, 1021, 730 cmÀ 1; HRMS: m/z calculated for
C25H30NO4Se [M+H]+ 488.1340 found 488.1348.
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J=7.1 Hz, 3H), 1.30 (t, J=7.1 Hz, 3H).; 13C NMR (100 MHz, CDCl3): δ
167.9, 167.5, 165.1, 142.4, 138.2, 136.9, 129.0 (q, J=4.1 Hz), 128.6,
Diethyl 2-(4-methoxyphenyl)-5-(phenylthio)-2H-pyrrole-4,4(3H)-
dicarboxylate (5ea):Yield: 114 mg (89%); 1H NMR (400 MHz, CDCl3):
δ 7.62 (d, J=8.1 Hz, 2H), 7.39–7.31 (m, 3H), 7.09 (d, J=8.6 Hz, 2H),
6.82 (d, J=8.6 Hz, 2H), 5.09 (t, J=7.5 Hz, 1H), 4.34 (q, J=7.12, 2H),
4.28 (q, J=7.12, 2H), 3.77 (s, 3H), 3.16 (dd, J=13.4, 7.3 Hz, 1H), 2.50
(dd, J=13.5, 7.8 Hz, 1H), 1.36 (t, J=7.1 Hz, 3H), 1.31 (t, J=7.2 Hz,
3H); 13C NMR (100 MHz, CDCl3): δ 168.0, 167.7, 167.3, 158.7, 134.9,
134.3, 130.1, 129.2, 129.0, 127.6, 113.8, 73.5, 73.1, 62.7, 62.5, 55.3,
127.8 (q, J=245 Hz), 127.3, 126.4, 95.0, 75.6, 74.8, 62.8, 62.7, 42.2,
19
~
14.1, 14.0.; F NMR (283 MHz, CDCl3): δ–62.6.; IR (neat) (v): 2924,
2857, 1723, 1469, 1379, 1267, 1178, 1067, 991, 806, 737 cmÀ 1; D-
Mass: m/z calculated for C23H22F3NO4Se [M+H]+ is 513.0666 found
572.9927, 571.9888, 569.9934, 446.0907, 306,1384.
Diethyl 5-(mesitylselanyl)-2-phenyl-2H-pyrrole-4,4(3H)-dicarboxy-
late (3ag): Yield: 130 mg (89%); Yellow viscous liquid; 1H NMR
(400 MHz, CDCl3): δ 7.30–7.25 (m, 2H), 7.24–7.18 (m, 1H), 7.14 (d, J=
7.0 Hz, 2H), 6.96 (s, 2H), 5.12 (t, J=7.6 Hz, 1H), 4.38–4.26 (m, 4H),
3.15 (dd, J=13.5, 7.5 Hz, 1H), 2.52 (s, 6H), 2.44 (dd, J=13.5, 7.8 Hz,
1H), 2.26 (s, 3H), 1.39 (t, J=7.2 Hz, 3H), 1.33 (t, J=7.1 Hz, 3H); 13C
NMR (100 MHz, CDCl3): δ 168.1, 168.0, 165.1, 143.4, 143.0, 139.5,
128.8, 128.4, 127.5, 126.4, 125.8, 75.2, 74.6, 62.7, 62.5, 42.8, 24.2,
~
43.4, 14.1, 14.0; IR (neat) (v): 2986, 2866, 1733, 1483, 1423, 1236,
1167, 1016, 712 cmÀ 1; HRMS: m/z calculated for C23H26NO5S [M+H]+
428.1532, found 428.1545.
Diethyl 2-(4-nitrophenyl)-5-(phenylthio)-2H-pyrrole-4,4(3H)-dicar-
1
boxylate (5fa): Yield: 89 mg (67%); Yellow viscous liquid; H NMR
(400 MHz, CDCl3): δ 8.15 (d, J=8.5 Hz, 2H), 7.65–7.60 (m, 2H), 7.43–
7.38 (m, 3H), 7.32 (d, J=8.7 Hz, 2H), 5.21 (t, J=7.7 Hz, 1H), 4.36 (q,
J=7.1 Hz, 2H), 4.31–4.26 (m, 2H), 3.26 (dd, J=13.5, 7.7 Hz, 1H), 2.49
(dd, J=13.4, 8.0 Hz, 1H), 1.38 (t, J=7.2 Hz, 3H), 1.31 (t, J=7.1 Hz,
3H); 13C NMR (100 MHz, CDCl3): δ 169.6, 167.5, 167.3, 150.2, 147.1,
134.6, 134.6, 129.5, 129.3, 127.2, 123.8, 73.1, 72.9, 62.9, 62.8, 42.7,
~
21.2, 14.2, 14.1; IR (neat) (v): 3041, 2901, 1734, 1550, 1446, 1255,
1083, 997, 935, 722 cmÀ 1. HRMS: m/z calculated for C25H30NO4Se [M
+H]+ 488.1340 found 488.1346.
Diethyl
5-((4-(tert-butyl)phenyl)selanyl)-2-phenyl-2H-pyrrole-
~
14.1, 14.0; IR (neat) (v): 2987, 2923, 1728, 1577, 1474, 1241, 1164,
4,4(3H)-dicarboxylate (3ah): Yield: 129.2 mg (86%); Yellow viscous
1032, 986, 761 cmÀ 1; HRMS: m/z calculated for C22H23N2O6S [M+H]+
1
liquid; H NMR (400 MHz, CDCl3): δ 7.61 (d, J=8.5 Hz, 2H), 7.34 (d,
443.1277, found 443.1291.
J=8.5 Hz, 2H), 7.28 (d, J=7.5 Hz, 2H), 7.25–7.21 (m, 1H), 7.17 (d, J=
7.0 Hz, 2H), 5.20 (t, J=7.7 Hz, 1H), 4.32 (q, J=7.2 Hz, 2H), 4.27 (q,
J=6.7 Hz, 2H), 3.17 (dd, J=13.5, 7.6 Hz, 1H), 2.44 (dd, J=13.6,
7.8 Hz, 1H), 1.36 (t, J=7.1 Hz, 3H), 1.32–1.28 (m, 12H); 13C NMR
(100 MHz, CDCl3): δ 168.1, 167.7, 165.9, 151.7, 142.7, 135.0, 128.5,
127.2, 126.5, 126.4, 124.5, 75.5, 74.9, 62.7, 62.6, 42.4, 34.8, 31.3, 14.1,
Diethyl 2-phenyl-5-(p-tolylthio)-2H-pyrrole-4,4(3H)-dicarboxylate
(5ab): Yield: 101 mg (82%); 1H NMR (400 MHz, CDCl3): δ 7.50 (d, J=
8.1 Hz, 2H), 7.31–7.25 (m, 2H), 7.24–7.13 (m, 5H), 5.13 (t, J=7.5 Hz,
1H), 4.34 (q, J=6.9 Hz, 2H), 4.27 (q, J=7.2 Hz, 2H), 3.19 (dd, J=13.4,
7.4 Hz, 1H), 2.52 (dd, J=13.4, 7.7 Hz, 1H), 2.33 (s, 3H), 1.36 (t, J=
7.1 Hz, 3H), 1.30 (t, J=7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ
168.0, 167.7, 142.9, 139.4, 135.5, 134.5, 130.1, 128.5, 127.2, 126.5,
~
14.0; IR (neat) (v): 3197, 3022, 2985, 2884, 1741, 1437, 1263,
1078 cmÀ 1
;
HRMS: m/z calculated for C26H32NO4Se [M+H]+
~
502.1497 found 502.1498.
73.7, 73.0, 62.7, 62.6, 43.4, 21.5, 14.2, 14.1; IR (neat) (v): 2980, 2932,
1727, 1446, 1247, 1054, 798, 687 cmÀ 1; HRMS: m/z calculated for
Diethyl
5-((2-oxo-2-phenylethyl)selanyl)-2-phenyl-2H-pyrrole-
C23H26NO4S [M+H]+ 412.1583, found 412.1591.
4,4(3H)-dicarboxylate (3ai):Yield: 118 mg (81%); Brown gum; 1H
NMR (400 MHz, CDCl3): δ 8.05–8.01 (m, 2H), 7.58–7.53 (m, 1H), 7.44–
7.34 (m, 4H), 7.32–7.27 (m, 3H), 5.22 (t, J=7.9 Hz, 1H), 4.69 (d, J=
13.8 Hz, 1H), 4.60 (d, J=13.9 Hz, 1H), 4.23 (q, J=7.1 Hz, 4H), 3.14
(dd, J=13.6, 7.4 Hz, 1H), 2.49 (dd, J=13.6, 8.4 Hz, 1H), 1.27 (td, J=
7.1, 1.1 Hz, 6H); 13C NMR (100 MHz, CDCl3): δ 196.0, 167.5, 167.5,
164.9, 142.3, 135.5, 133.6, 128.9, 128.7, 128.7, 127.5, 126.63, 75.1,
Diethyl 5-((4-methoxyphenyl)thio)-2-phenyl-2H-pyrrole-4,4(3H)-
dicarboxylate (5ac): Yield: 112 mg (88%); Colourless viscous liquid;
1H NMR (400 MHz, CDCl3): δ 7.53 (d, J=8.5 Hz, 2H), 7.29 (d, J=
7.1 Hz, 2H), 7.22–7.19 (m, 1H), 7.15 (d, J=7.1 Hz, 2H), 6.90 (d, J=
8.6 Hz, 2H), 5.12 (t, J=7.5 Hz, 1H), 4.34 (q, J=7.1 Hz, 2H), 4.26 (q,
J=7.1 Hz, 2H), 3.79 (s, 3H), 3.19 (dd, J=13.4, 7.4 Hz, 1H), 2.51 (dd,
J=13.6, 7.7 Hz, 1H), 1.37 (t, J=7.1 Hz, 3H), 1.30 (t, J=7.1 Hz, 3H).;
13C NMR (100 MHz, CDCl3): δ 168.5, 167.9, 167.7, 160.4, 142.2, 136.2,
128.4, 127.1, 126.4, 120.3, 114.8, 73.6, 72.9, 62.6, 62.5, 55.3, 43.4,
~
74.3, 62.8, 62.7, 42.5, 33.1, 14.0, 14.0; IR (neat) (v): 2988, 2929, 1730,
1584, 1446, 1257, 1170, 1090, 1002, 690 cmÀ 1; HRMS: m/z calculated
for C24H26NO5Se [M+H]+ 488.0976, found 488.0975.
~
14.1, 14.0.; IR (neat) (v): 2981, 2930, 1731, 1487, 1451, 1252, 1170,
Diethyl 2-phenyl-5-(phenylthio)-2H-pyrrole-4,4(3H)-dicarboxylate
(5aa): Yield: 102 mg (86%); Yellow viscous liquid; 1H NMR (400 MHz,
CDCl3): δ 7.66–7.61 (m, 2H), 7.40–7.33 (m, 3H), 7.31–7.26 (m, 2H),
7.22 (d, J=6.9 Hz, 1H), 7.17 (d, J=7.2 Hz, 2H), 5.15 (t, J=7.6 Hz, 1H),
4.35 (q, J=6.8 Hz, 2H), 4.28 (q, J=7.1 Hz, 2H), 3.21 (dd, J=13.3,
7.7 Hz, 1H), 2.53 (dd, J=13.6, 8.1 Hz, 1H), 1.37 (t, J=7.0 Hz, 3H), 1.31
(t, J=7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 167.9, 167.7, 167.7,
142.8, 134.3, 130.0, 129.2, 129.0, 128.5, 127.2, 126.4, 73.8, 73.1, 62.7,
1016, 935, 603 cmÀ 1; HRMS: m/z calculated for C23H26NO5S [M+H]+
428.1532 found, 428.1530.
Diethyl 5-((4-acetylphenyl)thio)-2-phenyl-2H-pyrrole-4,4(3H)-di-
1
carboxylate (5ad): Yield: 106 mg (81%); Yellow viscous liquid; H
NMR (400 MHz, CDCl3):δ 7.93 (d, J=8.2 Hz, 2H), 7.75 (d, J=8.2 Hz,
2H), 7.33–7.23 (m, 3H), 7.18 (d, J=7.1 Hz, 2H), 5.17 (t, J=7.7 Hz, 1H),
4.35 (q, J=7.16, 2H), 4.28 (q, J=7.08, 2H), 3.22 (dd, J=13.6, 7.4 Hz,
1H), 2.63–2.49 (m, 4H), 1.36 (t, J=7.1 Hz, 3H), 1.31 (t, J=7.1 Hz, 3H).;
13C NMR (100 MHz, CDCl3): δ 197.5, 167.7, 167.5, 166.5, 142.4, 136.9,
136.6, 133.5, 128.8, 128.6, 127.4, 126.4, 74.2, 73.3, 62.8, 62.7, 43.0,
~
62.6, 43.3, 14.1, 14.0; IR (neat) (v): 2979, 2928, 1718, 1446, 1368,
1267, 1096, 1011, 755, 687 cmÀ 1
HRMS: m/z calculated for
C22H24NO4S [M+H]+ 398.1426, found 398.1435.
;
~
26.7, 14.1, 14.0.; IR (neat) (v): 2987, 2926, 1733, 1680, 1588, 1442,
Diethyl
5-(phenylthio)-2-(p-tolyl)-2H-pyrrole-4,4(3H)-dicarboxy-
1358, 1251, 1174, 1082, 1014, 762 cmÀ 1; HRMS: m/z calculated for
C24H26NO5S [M+H]+ 440.1532, found 440.1523.
late (5ba): Yield: 107 (87%); Colourless viscous liquid; 1H NMR
(400 MHz, CDCl3): δ 7.66–7.59 (m, 2H), 7.39–7.29 (m, 3H), 7.10–7.05
(m„ 4H), 5.10 (t, J=7.6 Hz, 1H), 4.34 (q, J=7.16, 2H), 4.28 (q, J=7.12,
2H), 3.18 (dd, J=13.4, 7.4 Hz, 1H), 2.51 (dd, J=13.5, 7.9 Hz, 1H), 2.31
(s, 3H), 1.36 (t, J=7.1 Hz, 3H), 1.31 (t, J=7.1 Hz, 3H); 13C NMR
(100 MHz, CDCl3): δ 168.0, 167.7, 167.3, 139.8, 136.8, 134.3, 130.1,
129.1, 129.0, 126.3, 73.73, 73.2, 62.6, 62.5, 43.4, 21.2, 14.1, 14.0; IR
Diethyl 5-((4-nitrophenyl)thio)-2-phenyl-2H-pyrrole-4,4(3H)-dicar-
boxylate (5ae):Yield: 101 mg (76%); 1H NMR (400 MHz, CDCl3): δ
8.19 (d, J=8.7 Hz, 2H), 7.84 (d, J=8.8 Hz, 2H), 7.33–7.27 (m, 3H),
7.19 (d, J=7.1 Hz, 2H), 5.19 (t, J=7.7 Hz, 1H), 4.35 (q, J=7.12, 2H),
4.30 (m, 2H), 3.22 (dd, J=13.6, 7.4 Hz, 1H), 2.55 (dd, J=13.6, 8.0 Hz,
1H), 1.36 (t, J=7.2 Hz, 2H), 1.32 (t, J=7.1 Hz, 2H); 13C NMR
(100 MHz, CDCl3): δ 167.6, 167.3, 165.7, 147.6, 142.0, 139.4, 133.7,
128.7, 127.5, 126.4, 123.9, 74.3, 73.4, 62.9, 62.8, 42.7, 14.1, 14.0; IR
~
(neat) (v): 2981, 2929, 2856, 1729, 1583, 1451, 1246, 1180, 1078,
1012, 741 cmÀ 1; HRMS: m/z calculated for C23H26NO4S [M+H]+
412.1583, found 412.1589.
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~
(neat) (v): 2988, 2929, 1728, 1580, 1520, 1461, 1335, 1247, 1173,
1083 cmÀ 1; HRMS: m/z calculated for C22H23N2O6S [M+H]+ 443.1277
found, 443.1281.
Diethyl 5-phenyl-2-(phenylselanyl)-3H-pyrrole-3,3-dicarboxylate
(6aa): Yield: 36.2 mg (82%); Yellow viscous liquid; 1H NMR
(400 MHz, CDCl3):δ 7.78–7.74 (m, 4H), 7.41–7.38 (m, 3H), 7.35–7.30
(m, 3H), 6.63 (s, 1H), 4.33–4.27 (m, 4H), 1.33 (t, J=7.1 Hz, 6H); 13C
NMR (100 MHz, CDCl3):δ 173.8, 164.5, 158.2, 135.2, 132.4, 129.2,
Diethyl 5-(methylthio)-2-phenyl-2H-pyrrole-4,4(3H)-dicarboxylate
(5af): Yield: 91 mg (91%); Colourless viscous liquid; 1H NMR
(400 MHz, CDCl3): δ 7.37–7.25 (m, 5H), 5.15 (t, J=7.7 Hz, 1H), 4.34–
4.20 (m, 4 H), 3.16 (dd, J=13.5, 7.2 Hz, 1H), 2.59–2.48 (m, 4H), 1.32
(t, J=7.1 Hz, 3H), 1.28 (t, J=7.1 Hz, 3H).; 13C NMR (100 MHz, CDCl3):
δ 168.9, 168.8, 167.8, 142.8, 128.6, 127.4, 126.6, 73.6, 72.8, 62.6, 62.5,
~
128.7, 128.5, 127.3, 126.8, 114.9, 81.0, 63.1, 14.0; IR (neat) (v): 2986,
2914, 1743, 1481, 1247, 1093, 757 cmÀ 1; HRMS: m/z calculated for
C22H21NO4Se [M+H]+ 444.0714, found 444.0702.
~
43.6, 15.0, 14.1, 14.0.; IR (neat) (v) :2986, 2934, 1728, 1576, 1455,
1250, 1174, 1091, 1023, 757, 696 cmÀ 1; HRMS: m/z calculated for
C17H22NO4S [M+H]+ 336.1270 found, 336.1261.
Acknowledgements
Authors wish to acknowledge for financial support from SERB,
Department of Science and Technology, New Delhi, India and IIT
Ropar for infrastructural facilities. P.R.S. & P.K. would like to thank
IIT Ropar for their fellowships.
Diethyl 5-(benzylthio)-2-phenyl-2H-pyrrole-4,4(3H)-dicarboxylate
(5ag): Yield: 114 mg (93%); Yellow viscous liquid; 1H NMR
(400 MHz, CDCl3): δ 7.41–7.23 (m, 10H), 5.18 (t, J=7.7 Hz, 1H), 4.42–
4.33 (m, 2H), 4.30–4.18 (m, 4H), 3.16 (dd, J=13.5, 7.2 Hz, 1H), 2.53
(dd, J=13.4, 8.3 Hz, 1H), 1.29 (t, J=7.2 Hz, 3H), 1.24 (t, J=7.2 Hz,
3H); 13C NMR (100 MHz, CDCl3): δ 167.8, 167.7, 167.7, 142.7, 137.0,
129.3, 128.6, 128.5, 127.4, 127.3, 126.6, 73.7, 73.0, 62.6, 62.5, 43.4,
Conflict of Interest
~
36.5, 14.0, 14.0; IR (neat) (v): 2981, 2925, 1724, 1580, 1450, 1248,
1177, 1095, 1015, 701 cmÀ 1; HRMS: m/z calculated for C23H26NO4S
[M+H]+ 412.1583, found 412.1596.
The authors declare no conflict of interest.
Diethyl 2-((3-cyanophenyl)thio)-5-phenyl-4,5-dihydro-3H-pyrrole-
3,3-dicarboxylate (5ah): Yield (a): 154.1 mg (73%) (0.5 mmol of aryl
thiocyanate 4h and 0.5 mmol of cyclopropane 1a); Yield (b): 27 mg
(13%) (0.5 mmol of aryl thiocyanate 4h and 1.25 mmol of cyclo-
Keywords: Cyclopropanes
Selenopyrrolines · Thiopyrrolines
· Cycloaddition · Lewis acids ·
1
propane 1a); Yellow oil; H NMR (400 MHz, CDCl3):δ 7.93–7.92 (m,
1H), 7.87–7.84 (m, 1H), 7.62–7.60 (m, 1H), 7.49–7.45 (m, 1H), 7.33–
7.29 (m, 2H), 7.24–7.22 (m, 1H), 7.17–7.15 (m, 2H), 5.15 (t, J=7.7 Hz,
1H), 4.35 (q, J=7.1 Hz, 2H), 4.31–4.26 (m, 2H), 3.21 (dd, J=13.6,
7.4 Hz, 1H), 2.54 (dd, J=13.6, 7.9 Hz, 1H), 1.37 (t, J=7.1 Hz, 3H), 1.31
(t, J=7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 167.6, 167.4, 166.5,
142.2, 138.5, 137.4, 132.5, 132.4, 129.8, 128.7, 127.5, 126.4, 118.2,
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~
113.4, 74.1, 73.2, 62.9, 62.8, 42.9, 14.2, 14.1; IR (neat) (v): 2957, 2231,
1729, 1259, 1018, 700 cmÀ 1; HRMS: m/z calculated for C23H23N2O4S
[M+H]+ 423.1379, found 423.1385.
Diethyl
5-phenyl-2-(3-thiocyanatophenyl)-4,5-dihydro-3H-
pyrrole-3,3-dicarboxylate (5’ah): Yield: 23 mg (11%) (0.5 mmol of
aryl thiocyanate 4h and 1.25 mmol of cyclopropane 1a); Yellow oil;
1H NMR (400 MHz, CDCl3):δ 8.20–8.19 (m, 1H), 8.03–7.99 (m, 1H),
7.64–7.61 (m, 1H), 7.47 (t, J=8.2 Hz, 1H), 7.41–7.30 (m, 5H), 5.36–
5.32 (m, 1H), 4.34–4.25 (m, 2H), 4.19 (q, J=7.1 Hz, 2H), 3.38 (dd, J=
13.1, 7.0 Hz, 1H), 2.59 (dd, J=13.1, 8.4 Hz, 1H), 1.27 (t, J=7.1 Hz,
3H), 1.16 (t, J=7.1 Hz, 3H).; 13C NMR (100 MHz, CDCl3): δ 169.2,
168.1, 166.8, 141.9, 135.3, 131.9, 130.7, 130.4, 130.0, 128.8, 127.7,
126.8, 124.7, 110.3, 73.8, 71.2, 62.8, 62.7, 45.5, 14.1, 14.0.; IR (neat) (
v): 2981, 2187, 1752, 1236, 992, 717 cmÀ 1; HRMS: m/z calculated for
~
C23H23N2O4S [M+H]+ 423.1379, found 423.1387.
Diethyl 2-((3-(4,4-bis(ethoxycarbonyl)-2-phenyl-3,4-dihydro-2H-
pyrrol-5-yl)phenyl)thio)-5-phenyl-4,5-dihydro-3H-pyrrole-3,3-di-
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6805–6810.
carboxylate (5’’ah): Yield
: 75 mg (22%) (0.5 mmol of aryl
thiocyanate 4h and 1.25 mmol of cyclopropane 1a); Blue oil; 1H
NMR (400 MHz, CDCl3): δ 7.94–7.84 (m, 1H), 7.82–7.68 (m, 4H), 7.59
(t, J=7.7 Hz, 2H), 7.50–7.45 (m, 1H), 7.39–7.33 (m, 4H), 7.17–7.14 (m,
2H), 5.37–5.28 (m, 1H), 5.18–5.09 (m, 1H), 4.36–4.20 (m, 8H), 3.40–
3.31 (m, 1H), 3.25–3.14 (m, 1H), 2.60–2.50 (m, 2H), 1.44–1.30 (m, 8H),
1.18–1.08 (m, 4H).; 13C NMR (100 MHz, CDCl3): δ 167.9, 167.6, 167.4,
166.4, 142.2, 138.5, 137.3, 132.5, 132.4, 131.0, 129.8, 128.7, 127.5,
126.4, 118.2, 113.4, 74.0, 73.1, 68.2, 62.9, 62.8, 43.0, 38.8, 32.0, 14À.31,
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Org. Chem. 2019, 4694–4700.
~
14.2, 14.2, 14.1.; IR (neat) (v): 2927, 1728, 1258, 1066, 699 cm
;
HRMS: m/z calculated for C38H41N2O8S [M+H]+ 685.2584, found
685.2585.
[11] a) A. O. Chagarovskiy, E. M. Budynina, O. A. Ivanova, I. V. Trushkov,
Chem. Heterocycl. Compd. 2010, 46, 120–122; b) A. O. Chagarovskiy, K. L.
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4688
© 2021 Wiley-VCH GmbH

Full Papers
doi.org/10.1002/ejoc.202100846
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Compd. 2012, 48, 825–827.
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Li, J. S. Johnson, J. Am. Chem. Soc. 2008, 130, 8642–8650.
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Manuscript received: July 16, 2021
Revised manuscript received: August 9, 2021
Accepted manuscript online: August 10, 2021
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4689
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