Studies on the reactivity of N-(3-thienyl)carbamates

Article abstract of DOI:10.1039/b003580g

Tert-Butyl 2-allyl- and N-allyl-3-thienylcarbamates were used as substrates for the preparation of thieno-[3,2-b]pyrroles 9 and 5,6-dihydrothieno[3,2-b]pyrroles 10. Pd-catalyzed cyclization of N-allyl-(2-bromo-3-thienyl)carbamates 12 has allowed access to

Full text of DOI:10.1039/b003580g

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Studies on the reactivity of N-(3-thienyl)carbamates
Delphine Brugier, Francis Outurquin and Claude Paulmier*
Laboratoire de Synthèse Thio- et Séléno-organique, IRCOF-UFR Sciences,
Université de Rouen, F-76821 Mont Saint Aignan Cedex, France
1
Received (in Cambridge, UK) 4th May 2000, Accepted 10th November 2000
First published as an Advance Article on the web 13th December 2000
tert-Butyl 2-allyl- and N-allyl-3-thienylcarbamates were used as substrates for the preparation of thieno-
[3,2-b]pyrroles 9 and 5,6-dihydrothieno[3,2-b]pyrroles 10. Pd-catalyzed cyclization of N-allyl-(2-bromo-3-
thienyl)carbamates 12 has allowed access to thienopyrroles 9. The radical route has led to the formation
of a dihydrothienopyrrole 10 or a tetrahydrothienopyridine 19 according to the β-substitution of the allyl
substituent. The nucleophilic participation of the tert-butoxycarbonyl group occurred during the selenium
or iodine-induced cyclization of tert-butyl 2-allyl- or N-allyl-3-thienylcarbamates. The formation of the
thienooxazepinone 25 and N-(3-thienyl)oxazolidinones 28 and 29 was observed.
Indole derivatives display a wide range of biological activity.1
For comparison, the study of thiophene isosteres is of great
interest. The synthesis of thieno[3,2-b]pyrroles has been
described but low yields were observed.2–4 The multistep
methods used involve cyclization of 3-aminothiophene deriv-
atives according to Reissert, Bischler or Fischer modified
procedures. More recently, Gronowitz et al. have prepared
thieno[3,2-b]pyrroles using Pd-catalyzed coupling reactions.5
Few works are devoted to 5,6-dihydrothieno[3,2-b]pyrroles5
and, in particular, to their preparation.6
We are interested in the reactivity of 3-aminothiophene 1,
3,4-diaminothiophene 2 and their carbamates: alkyl (3-thienyl)-
carbamates 3, tert-butyl (4-amino-3-thienyl)carbamate 4 and
di-tert-butyl (thiophene-3,4-diyl)dicarbamate 57 (Scheme 1).
Scheme 2
According to recent preparations of indoles and azaindoles, we
have tried to achieve the cyclization of compounds 11 in the
presence of palladium() salts9 or copper() iodide,10 but the
reactions were unsuccessful. Gronowitz et al. reported a two
step procedure with both Pd-catalyzed carbon–carbon bond
formation and cyclization.5a Our result seems to demonstrate
that carbamates 11 and 15b (R = SiMe3) were not intermediates
in this reaction.
The carbamate 11b (R = SiMe3) was treated with sodium
ethoxide in ethanol.11 The formation of thienopyrrole was not
Scheme 1
Halogenation of these compounds was recently studied and
carbamates 6–8 are now readily available.8
We now report our results concerning the access to 4-tert-
butoxycarbonylthieno[3,2-b]pyrroles
9
and 4-tert-butoxy-
carbonyl 5,6-dihydrothieno[3,2-b]pyrroles 10 from 3-amino-
thiophene derivatives. Four routes were tested (Scheme 2). The
cyclization of alkyl (2-alkynyl-3-thienyl)carbamates 11 was
studied first. Methods involving Pd-catalyzed coupling
reactions, radical and anionic cyclizations were then investi-
gated. tert-Butyl N-allyl(2-bromo-3-thienyl)carbamates 12,
tert-butyl (2-allyl-3-thienyl)carbamates 13 and tert-butyl
N-allyl(3-thienyl)carbamates 14 were considered as potential
precursors.
observed and only the 2-ethynylthiophenes 11a and 15a were
respectively obtained. This result shows that this method,
efficient for the synthesis of indoles, cannot be transposed to
the thiophene isosteres.
We then prepared several N-allylated [2-halo or 2-phenyl-
selanyl-3-thienyl]carbamates 12 with the goal to test the
palladium-catalyzed, radical and ionic routes. Compounds 12
were easily obtained by N-allylation of (2-halo or 2-phenyl-
selanyl-3-thienyl)carbamates 6 (Scheme 3, Table 1). The same
reaction was carried out on halo dicarbamates 7b, 8a and 8b
providing the bis(N-allylcarbamates) 16 and 17 in good yields
We have recently described the synthesis of alkyl (2-ethynyl-
3-thienyl)carbamates 11 by Pd-catalyzed coupling reaction
between acetylene compounds and the bromo carbamate 6a.8
DOI: 10.1039/b003580g
J. Chem. Soc., Perkin Trans. 1, 2001, 37–43
This journal is © The Royal Society of Chemistry 2001
37

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Table 1 N-Allyl 2-substituted 3-thienylcarbamates 12
Table 2 Thieno[3,2-b]pyrrole and thieno[3,2-b]pyridine derivatives 10
and 19
No.
X
R
RЈ
E:Z
Yield (%)
Entry
X
R
RЈ
Product
Yield (%)
12a
12b
12c
12d
12e
12f
Br
Br
Br
Br
I
H
H
Me
Ph
H
H
Me
H
H
H
—
—
90:10
100:0
—
—
72
87
51
50
94
68
1
2
3
4
5
6
Br
I
SePh
Br
Br
Br
H
H
H
H
Me
Ph
H
H
H
Me
H
10a
10a
10a
19
10b
10c
68
73
69
76
67
85
SePh
H
H
H
Scheme 3 Reagents and conditions: (i) nBuLi (2.5 eq.), THF, Ϫ78 ЊC
then PhSeSePh, Ϫ20 ЊC; (ii) NaH, THF then allylic halide, 20 ЊC.
Scheme 6
providing the dihydrothienopyrrole 10 with a good yield. Com-
parable results were observed for X = Br, I and SePh (compare
entries 1, 2 and 3). According to a 6-endo process, the tetra-
hydrothienopyridine 19 was the major product formed from
12b (76% yield). The corresponding dihydrothienopyrrole 20
was also present as a minor product (19–20, 95:5).
Scheme 4
(Scheme 4). Compounds 16 and 17 have given very complex 1H
and 13C NMR spectra, which indicate stabilized conformers
resulting from an important steric hindrance.
tert-Butyllithium treatment of N,N-diallylated 2-haloanilines,
in a polar solvent or in the presence of a chelating agent, allows
cyclization at room temperature.12 The mechanism involves the
successive formation of two carbanionic species. In our hand,
the lithium–bromine exchange occurred but no cyclization took
place. We have observed the quantitative formation of the
debrominated compounds 14a from 12a (R = RЈ = R1 = H,
X = Br) and 18 from 17a.
Palladium-catalyzed and radical cyclizations were unsuccess-
ful in the case of dicarbamates 16 and 17. The cleavage of the
C–X bond was never observed. Steric hindrance probably
prevents palladium insertion or radical formation.
The electrophilic selenium-induced cyclization method14 was
then considered. tert-Butyl (2-allyl-3-thienyl)carbamate 13a,
prepared in a quantitative yield by metallation–allylation of 3a,
was treated with an electrophilic selenium reagent (Scheme 7).
Using PhSeBr or N-(phenylselanyl)phthalimide (NPSP), no
reaction was observed even after several days. Phenylselanyl
The palladium-catalyzed cyclization of a tert-butyl N-allyl-
ated (2-iodo-3-thienyl)carbamate, leading to a thieno[3,2-b]-
pyrrole derivative, has been described5c but the reaction was not
extensively studied. We have applied this procedure to the
synthesis of the 6-methyl and 6-benzylthieno[3,2-b]pyrrole
derivatives 9a (R = H) and 9d (R = Ph). The iodothiophene 12e
was a better substrate than the bromo analog 12a for access to
9a (Scheme 5).
Scheme 5 Reagents and conditions: (i) Pd(PPh3)4, K2CO3, DMF, 60 ЊC.
Scheme 7 Reagents and conditions: (i) n-BuLi (2.5 eq.), THF, Ϫ78 ЊC
then allylbromide, Ϫ10 ЊC; (ii) PhSeCl (1.5 eq.), CH2Cl2, Na2CO3
(1eq.); (iii) PhSeSePh (0.6 eq.), Phl(OAc)2 (excess), CH3CN; (iv)
SiO2, CH2Cl2.
The radical cyclization13 of carbamates 12 (X = Br, I, SePh)
was also achieved (Scheme 6, Table 2). When RЈ = H, the initial
thienyl radical underwent exclusively 5-exo trigonal cyclization
38
J. Chem. Soc., Perkin Trans. 1, 2001, 37–43

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triflate † led to a complex and untractable mixture with
consumption of the substrate. The generation of PhSeϩ from
diphenyl diselenide and PhI(OAc)2 15 has led to the formation of
the regioisomeric addition products 21a and 22a (thermo-
dynamic and kinetic adducts, respectively). A slow and partial
isomerisation 22a → 21a occurred during the chromato-
graphic separation. This reaction could be considered as a
formal addition of “PhSeOAc” (Scheme 7). With PhSeCl, only
the thermodynamic adduct 21b was formed, but was not
isolated in a pure form. The cyclization occurred during silica
gel chromatography. Three heterocyclic products were formed
and isolated: the expected dihydrothienopyrrole 23, the tetra-
hydrothienopyridine 24 and the thienooxazepine 25 (ratio: 23–
24–25, 50:15:35). The formation of 23 and 24 was the result of
5- and 7-exo cyclization processes involving the thermodynamic
addition product 21b or the seleniranium ion A with respective
attacks of the nitrogen and oxygen atoms of the carbamate
functional group (Scheme 7).
We have previously studied the strong enamine character of
β-aminothiophenes 1 and 2.7 Under acid catalysis, α-alkylation
of the nucleus was efficiently achieved using an aldehyde and
PhSeH as reducing agent. We were interested in evaluating the
nucleophilicity of the α-carbon towards that of a seleniranium
ion. We have therefore prepared the N-allylated compounds
14a, 18 (already obtained by debromination of 12a and 17a),
and 27 (Scheme 8). The synthesis of the tert-butyl N-allyl-3-
providing the 2-phenylselanylthiophene derivative 30 isolated in
a good yield (Scheme 8).
To prevent the participation of the functional group, we
have applied the reaction to tertiary N-allyl amines. N-Allyl-3-
(methylamino)thiophene 3116 and N,NЈ-diallyl-3,4-bis(methyl-
amino)thiophene 32 were prepared by LiAlH4 reduction of the
N-allylated carbamates 14a and 18, respectively (Scheme 9).
Scheme 9
In each case, the reaction with PhSeCl (1.5 eq.) has not allowed
the cyclization. Complex and untractable mixtures of products
were formed. The reaction was not investigated further.
This work has shown that the synthesis of thieno[3,2-
b]pyrroles from 3-aminothiophene derivatives cannot be
achieved by the methods which are efficient for the preparation
of indoles from 2-allyl or N-allylanilines. We succeeded, how-
ever, in the synthesis of tert-butyl 6-alkylthieno[3,2-b]pyrrole-
4-carboxylates 9 by Pd-catalyzed cyclization of tert-butyl
N-allyl(2-halo-3-thienyl)carbamates 12. The radical cyclization
of the same substrates 12 (X = Br, I, SePh) has given an access
to the 5,6-dihydrothieno[3,2-b]pyrroles 10 and 4,5,6,7-tetra-
hydrothieno[3,2-b]pyridine 19 according to the nature of the
allyl substituent. The PhSe-induced cyclization of tert-butyl
2-allyl-3-thienylcarbamate 13a has shown competitive partic-
ipation of the functional group with formation of the
thienooxazepinone 25. A comparable O-nucleophilic attack
by the Boc group was observed with the formation of the the
oxazolidinones 28 and 29 during selenium- or iodine-induced
cyclization of the N-allylated thienylcarbamates 14a and 18,
respectively.
Experimental
Di-tert-butyl (thiophene-3,4-diyl)dicarbamate 5,17 tert-butyl
(4-amino-3-thienyl)carbamate 4,7e tert-butyl (2-bromo-3-
thienyl)carbamate 6a,18 the halothiophene derivatives 6–88 and
acetylene compounds 11b and 15b8 were prepared as described
elsewhere. All solvents were distilled before use and light
petroleum refers to the fraction with bp 40–60 ЊC. THF was
distilled over sodium–benzophenone and triethylamine was
dried over sodium hydride. The chromatographic separations
were achieved on silica gel (0.060–0.200 nm, pore diameter ca.
4 nm) available from ACROS. 1H and 13C NMR spectrum were
recorded on Brucker AC 200 and DPX 300 instruments.
Scheme 8 Reagents and conditions: (i) NaH, THF, allyl bromide, 5 h;
(ii) NaH, THF, allyl bromide, 20 h; (iii) PhSeCl, CH2Cl2, 20 ЊC, 12 h;
(iv) N-iodosuccinimide, CCl4, ∆, 12 h.
Attempted cyclization of 2-(trimethylsilylethynyl)thiophenes 11b
and 15b
thienylcarbamate 14a has been previously described.16 NaH
treatment of the dicarbamate 5, followed by addition of allyl
bromide, afforded the dicarbamate 18 or the thienoimidazolone
26 depending on the reaction time. The monoallyl diamine
derivative 27 was prepared, in good yield, from the amino-
carbamate 4. In the reaction of PhSeCl with the N-allylated
thienylcarbamates 14a and 18, the O-nucleophilicity of the
carbamate group was also efficient and the oxazolidinones 28
and 29a were formed respectively. An analogous reactivity was
observed in the reaction of N-iodosuccinimide with the di-
carbamate 18. The bis(oxazolidinone) 29b was obtained albeit
in a poor yield (37%).
The carbamate 11b (0.295 g, 1 mmol) was added to a freshly
prepared solution of NaOEt (5 mmol) in ethanol (10 ml). The
mixture was heated on reflux for 9 h under argon. The solvent
was eliminated and the residue was treated with water and
extracted with CH2Cl2. The organic layer was concentrated and
silica gel chromatography (eluent: AcOEt) afforded the thien-
ylacetylene 11a. With the same treatment, 15b has led to 15a.
tert-Butyl (2-ethynyl-3-thienyl)carbamate 11a. Oil. Yield =
62%. 1H NMR (CDCl3), δ: 7.61 (d, 1H, H5, J = 5.5 Hz), 7.14 (d,
1H, H4, J = 5.5 Hz), 6.91 (br s, 1H, NH), 3.63 (s, 1H, CH), 1.50
(s, 9H, CH3). Anal. calc. for C11H13NO2S: C, 59.17; H, 5.87; N,
6.27; found: C, 58.67; H, 6.02; N, 5.94%.
PhSeCl treatment of the N-allylated thiophenediamine
derivative 27 has led to an electrophilic aromatic substitution
Di-tert-butyl (2-ethynylthiophene-3,4-diyl)dicarbamate 15a.
1
Oil. Yield = 68%. H NMR (CDCl3), δ: 8.00 (br s, 1H, NH),
† The IUPAC name for triflic acid is trifluoromethanesulfonic acid.
J. Chem. Soc., Perkin Trans. 1, 2001, 37–43
39

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7.37 (s, 1H, H5), 6.54 (br s, 1H, NH), 3.58 (s, 1H, CH), 1.51
(s, 9H), 1.48 (s, 9H,). 13C NMR (CDCl3), δ: 153.8, 152.9 (CO),
132.3, 130.5 (C3, C4), 110.9 (C5, CH), 88.2 (C), 81.9, 80.2
(C(CH3)3), 28.1, 27.9 (CH3). Anal. calc. for C16H22N2O4S: C,
56.79; H, 6.55; N, 8.28; found: C, 56.55; H, 6.08; N, 8.18%.
C12H16INO2S: C, 39.46; H, 4.42; N, 3.84; found: C, 40.00; H,
4.52; N, 4.10%.
tert-Butyl N-allyl(2-phenylselanyl-3-thienyl)carbamate 12f.
1
Oil. Yield = 68%. H NMR (CDCl3), δ: 7.32–7.28 (m, 6H, Ph,
H4), 6.81 (br s, 1H, H5), 5.82–5.71 (m, 1H, Hβ), 5.11–4.96 (m,
2H, Hγ), 4.07 (m, 2H, Hα), 1.35 (s, 9H, CH3). 13C NMR
(CDCl3), δ: 154.1 (CO), 144.6 (C3), 133.7 (Cβ), 130.4 (C5), 132.5,
129.0, 127.4 (Ph), 126.7 (C4), 117.1 (Cγ), 80.9 (C(CH3)3), 52.2
(Cα), 28.0 (CH3). Anal. calc. for C18H21NO2SSe: C, 54.82; H,
5.37; N, 3.55; S, 8.13; found: C, 54.86; H, 6.05; N, 2.96; S,
8.52%.
N-Allylation of halocarbamates 6
A solution of bromocarbamate 6a (0.278 g, 1 mmol) and
sodium hydride (0.120 g, 5 mmol) in THF (50 ml) was stirred
for 30 min at room temperature. Allyl bromide (0.605 g,
5 mmol) was then added and the mixture was stirred for 5 h.
After cooling to 0 ЊC, the reaction was treated with a sat. aq.
NaCl solution (10 ml). The organic layer was dried and the
solvent was eliminated. The oily residue was chromatographed
(eluent: CH2Cl2–light petroleum, 1:1) affording N-allyl(2-
bromo-3-thienyl)carbamate 12a. The other compounds 12 were
obtained in a similar way from the corresponding carbamates
6 and the appropriate allylic bromide. The N-allylated halo-
dicarbamates 16, 17a and 17b were prepared from dicarbamates
7b, 8a and 8b respectively, using double the amount of NaH
and allyl bromide.
Di-tert-butyl
N,NЈ-diallyl(2-iodothiophene-3,4-diyl)dicarb-
1
amate 16. Oil. Yield = 80%. H NMR (CDCl3), δ: 7.17 (s, 1H,
H5), 6.05–5.65 (m, 2H, Hβ), 5.13–5.02 (m, 4H, Hγ), 4.35–3.85
(m, 4H, Hα), 1.40 (s, 9H, CH3), 1.38 (s, 9H, CH3). 13C NMR
(CDCl3), δ: 153.8, 152.9 (CO), 133.3 (Cβ), 125.9 (C5), 117.6,
116.5 (Cγ), 80.3, 80.1 (C(CH3)3), 51.9, 50.9 (Cα), 27.8 (CH3).
Anal. calc. for C20H29IN2O4S: C, 46.16; H, 5.62; N, 5.38; S, 6.16;
found: C, 46.35; H, 5.98; N, 5.66; S, 6.02%.
Di-tert-butyl
N,NЈ-diallyl(2,5-dibromothiophene-3,4-diyl)-
tert-Butyl N-allyl(2-bromo-3-thienyl)carbamate 12a. Mp =
38 ЊC, yield = 72%. 1H NMR (CDCl3), δ: 7.17 (d, 1H, H4,
J = 5.8 Hz), 6.75 (br s, 1H, H5), 5.92–5.77 (m, 1H, Hβ), 5.14–5.05
dicarbamate 17a. Oil. Yield = 91%. 1H NMR (CDCl3), δ: 5.97–
5.75 (m, 2H, Hβ), 5.14–5.02 (m, 4H, Hγ), 4.45–3.50 (m, 4H, Hα),
1.46 (s, 9H, CH3), 1.37 (s, 9H, CH3). 13C NMR (CDCl3),
δ: 152.9 (CO), 133.5, 133.0 (Cβ), 118.6, 118.0, 117.4 (Cγ), 80.9
(C(CH3)3), 50.8 (Cα), 28.0 (CH3). Anal. calc. for C20H28Br-
2N2O4S: C, 43.49; H, 5.11; N, 5.07; S, 5.80; found: C, 43.56; H,
5.16; N, 5.02; S, 5.64%.
(m, 2H, Hγ), 4.10 (d, 2H, Hα, J = 5.6 Hz), 1.37 (s, 9H, CH3). 13
C
NMR (CDCl3), δ: 153.0 (CO), 139.0 (C3), 132.9 (Cβ), 126.2 (C5),
124.0 (C4), 116.9 (Cγ), 108.7 (C2), 79.7 (C(CH3)3), 50.9 (Cα), 27.6
(CH3). Anal. calc. for C12H16BrNO2S: C, 45.29; H, 5.07; N,
4.40; S, 10.07; found: C, 45.25; H, 4.97; N, 4.60; S, 10.21%.
tert-Butyl N-(2-methylprop-2-enyl)(2-bromo-3-thienyl)carb-
amate 12b. Mp = 64 ЊC, yield = 87%. 1H NMR (CDCl3), δ: 7.14
(d, 1H, H4, J = 5.8 Hz), 6.76 (br s, 1H, H5), 4.77 (s, 2H, Hγ), 4.06
(s, 2H, Hα), 1.73 (s, 3H, CH3), 1.37 (s, 9H, CH3). 13C NMR
(CDCl3), δ: 153.3 (CO), 140.4 (Cβ), 139.2 (C3), 126.0 (C5), 123.9
(C4), 112.3 (Cγ), 108.4 (C2), 79.7 (C(CH3)3), 54.0 (Cα), 27.6
(C(CH3)3),19.6 (CH3). Anal. calc. for C13H18BrNO2S: C, 46.99;
H, 5.46; N, 4.22; found: C, 46.98; H, 5.69; N, 4.07%.
Di-tert-butyl
N,NЈ-diallyl(2,5-diiodothiophene-3,4–diyl)-
dicarbamate 17b. Mp = 105–120 ЊC, yield = 73%. 1H NMR
(CDCl3), δ: 6.03–5.80 (m, 2H, Hβ), 5.15–5.02 (m, 4H, Hγ), 4.45–
3.50 (m, 4H, Hα), 1.50 (s, 9H, CH3), 1.39 (s, 9H, CH3). 13C
NMR (CDCl3), δ: 152.7 (CO), 133.8, 133.2, 132.8 (Cβ), 118.6,
117.9, 117.4 (Cγ), 81.0, 80.9, 79.9 (C(CH3)3), 52.3, 50.9 (Cα),
28.1 (CH3). Anal. calc. for C20H28I2N2O4S: C, 37.17; H, 4.37;
N, 4.33; S, 4.96; found: C, 37.27; H, 4.64; N, 4.11; S, 4.95%.
tert-Butyl N-but-2-enyl(2-bromo-3-thienyl)carbamate 12c.
Preparation of thienopyrroles 9a and 9d
1
Oil. yield = 51%, (90:10 E:Z mixture). E Isomer: H NMR
(CDCl3), δ: 7.12 (d, 1H, H4, J = 5.8 Hz), 6.67 (br s, 1H, H5),
5.55–5.37 (m, 2H, Hβ, Hγ), 3.98 (m, 2H, Hα), 1.54 (d, 3H, Hδ,
J = 7.4 Hz), 1.32 (s, 9H, CH3). 13C NMR (CDCl3), δ: 153.5
(CO), 139.4 (C3), 128.6 (Cβ), 126.6 (Cγ), 125.9 (C5), 124.0 (C4),
109.1 (C2), 79.9 (C(CH3)3), 50.5 (Cα), 27.9 (CH3),17.4 (Cδ).
Anal. calc. for C13H18BrNO2S: C, 46.99; H, 5.46; N, 4.22;
Potassium carbonate (0.512 g, 4 mmol) and Pd(PPh3)4 (0.057 g,
0.05 mmol) were successively added to a degassed solution of
N-allyl(2-halo-2-thienyl)carbamate 12a (12d or 12e) (1 mmol)
in DMF (3 ml). The reaction mixture was stirred for 30 min at
room temperature and 5 h at 60 ЊC and then diluted with ether
(25 ml) and water (10 ml) and filtered through a Celite pad. The
organic layer was dried and evaporated. The thienopyrrole 9a
(or 9d) was isolated after silica gel chromatography of the oily
residue (eluent: light petroleum–CH2Cl2, 75:25).
1
found: C, 47.31; H, 5.72; N, 4.58%. Z isomer not isolated: H
NMR (CDCl3), δ: 7.12 (d, 1H, H4, J = 5.8 Hz), 6.67 (br s, 1H,
H5), 5.55–5.37 (m, 2H, Hβ, Hγ), 4.12 (m, 2H, Hα), 1.45 (d, 3H,
Hδ, J = 7.1 Hz), 1.32 (s, 9H, CH3).
tert-Butyl 6-methyl-4H-thieno[3,2-b]pyrrole-4-carboxylate 9a.
Oil. Yield = 55% from 12a and 70% from 12e. 1H NMR
(CDCl3), δ: 7.30 (br s, 1H, H2), 7.13 (m, 2H, H3, H5), 2.20 (s, 3H,
CH3), 1.63 (s, 9H, CH3). 13C NMR (CDCl3), δ: 148.3 (CO),
137.4 (C3a), 128.2 (C6a), 124.2 (C2), 120.8 (C5), 115.7 (C6), 114.9
(C3), 82.8 (C(CH3)3), 27.7 (CH3), 10.8 (CH3). Anal. calc. for
C12H15NO2S: C, 60.73; H, 6.37; N, 5.90; S, 13.51; found: C,
60.13; H, 6.02; N, 5.23; S, 13.54%.
tert-Butyl N-(3-phenylprop-2-enyl)(2-bromo-3-thienyl)carb-
amate 12d. Oil. Yield = 50%. E Isomer: 1H NMR (CDCl3),
δ: 7.30–7.10 (m, 6H, Ph, H4), 6.70 (br s, 1H, H5), 6.35 (d, 1H,
Hγ, J = 16 Hz), 6.16 (dt, 1H, Hβ, J = 16, 6.5 Hz), 4.14 (d, 2H,
Hα, J = 6.5 Hz), 1.34 (s, 9H, CH3). 13C NMR (CDCl3), δ: 153.4
(CO), 136.2 (Cβ), 132.3, 129.0, 127.1, 126.3, 126.2, 125.9 (CPh,
Cγ, C5), 124.0 (C4), 109.2 (C2), 80.0 (C(CH3)3), 50.5 (Cα), 27.7
(CH3). Anal. calc. for C18H20BrNO2S: C, 54.83; H, 5.11; N,
3.55; S, 8.13; found: C, 55.02; H, 5.02; N, 3.88; S, 8.56%.
tert-Butyl 6-benzyl-4H-thieno[3,2-b]pyrrole-4-carboxylate 9d.
1
Oil. Yield = 50%. H NMR (CDCl3), δ: 7.40–7.20 (m, 7H, Ph,
tert-Butyl N-allyl(2-iodo-3-thienyl)carbamate 12e. Oil. Yield =
94%. 1H NMR (CDCl3), δ: 7.17 (d, 1H, H4, J = 5.8 Hz), 6.75 (br
s, 1H, H5), 5.92–5.77 (m, 1H, Hβ), 5.14–5.05 (m, 2H, Hγ), 4.10
(d, 2H, Hα, J = 5.6 Hz), 1.37 (s, 9H, CH3). 13C NMR (CDCl3),
δ: 153.6 (CO), 133.5 (Cβ), 129.6 (C5), 123.5 (C4), 117.5 (Cγ),
116.0 (C2), 80.3 (C(CH3)3), 51.6 (Cα), 28.1 (CH3). Anal. calc. for
H2, H5), 7.11 (d, 1H, H3, J = 5.5 Hz), 4.90 (s, 2H, CH2), 1.63 (s,
9H, CH3). 13C NMR (CDCl3), δ: 148.6 (CO), 140.3, 128.3,
127.3, 125.2 (CPh), 138.4 (C3a), 128.2 (C6a), 124.9 (C2), 120.8
(C5), 114.8 (C6), 111.1 (C3), 83.3 (C(CH3)3), 32.6 (CH2), 27.7
(CH3). Anal. calc. for C18H19NO2S: C, 68.98; H, 6.11; N, 4.47; S,
10.23; found: C, 69.05; H, 6.35; N, 4.63; S, 10.22%.
40
J. Chem. Soc., Perkin Trans. 1, 2001, 37–43

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Radical cyclization of N-allyl(2-halo-3-thienyl)carbamates 12
Formal “PhSeOAc” addition to the 2-allylthiophene 13a
A degassed solution of carbamate 12 (1 mmol) in toluene (10
ml) containing AIBN (0.01 g) and tributyltin hydride (0.437 g,
1.5 mmol) was stirred under reflux for 8 h. The solvent was
evaporated and silica gel chromatography (eluent: light
petroleum–CH2Cl2, 80:20, then CH2Cl2) afforded the dihydro-
thienopyrrole 10 (or the tetrahydrothienopyridine 19 for 12b).
Diphenyl diselenide (0.375 g, 1.2 mmol) and (diacetoxy-λ3-
iodanyl)benzene (0.754 g, 2.6 mmol) were added to a solution
of 13a (0.478 g, 2 mmol) in CH3CN (6 ml). The mixture was
stirred overnight and treated with sat. aq. NaCl solution. The
organic layer was dried and evaporated. The addition products
21a and 22a were separated by silica gel chromatography (elu-
ent: light petroleum–CH2Cl2, 1:1). A partial isomerization of
22a into 21a was observed during the purification.
tert-Butyl
5,6-dihydro-6-methyl-4H-thieno[3,2-b]pyrrole-4-
1
carboxylate 10a. Oil. Yield = 68%. H NMR (CDCl3), δ: 7.16,
6.87 (2br s, 1H, H2), 7.06 (d, 1H, H3, J = 5.1 Hz), 4.47–4.37 (m,
1H, H5), 3.85–3.76 (m, 1H, H5), 3.59–3.48 (m, 1H, H6), 1.53 (s,
9H, CH3), 1.29 (d, 3H, CH3, J = 6.7 Hz). 13C NMR (CDCl3),
δ: 151.2, 150.9 (CO), 144.5, 143.7 (C3a), 128.9, 128.4 (C6a), 126.7
(C2), 116.0, 115.6 (C3), 80.2, 79.6 (C(CH3)3), 60.3, 59.8 (C5),
33.7, 33.0 (C6), 28.0, 27.7 (CH3), 21.3 (CH3). Anal. calc. for
C12H17NO2S: C, 60.22; H, 7.16; N, 5.85; found: C, 59.84; H,
tert-Butyl {2-[2-acetoxy-3-(phenylselanyl)propyl]-3-thienyl}-
carbamate 21a. Oil. Yield = 40%. H NMR (CDCl3), δ: 7.48–
1
7.44 (m, 2H, Ph), 7.24–7.19 (m, 4H, Ph, H5), 7.02 (d, 1H, H4,
J = 5.5 Hz), 6.90 (br s, 1H, NH), 4.99 (m, 1H, CHOAc), 3.12–
2.93 (m, 4H, CH2, CH2), 1.92 (s, 3H, CH3), 1.44 (s, 9H, CH3).
13C NMR (CDCl3), δ: 170.2 (CO), 152.9 (CO), 134.2, 132.6,
129.1, 128.1 (Ph), 122.4 (C5), 80.3 (C(CH3)3), 74.0 (CHOAc),
31.5 (CH2), 30.3 (CH2), 28.2 (CH3), 20.9 (CH3). IR (KBr): 3344,
3058, 2978, 2931, 1731, 1582, 1368 cmϪ1. Anal. calc. for
C20H25NO4SSe: C, 52.86; H, 5.54; N, 3.08; S, 7.05; found: C,
52.88; H, 5.65; N, 3.18; S, 6.98%.
7.02; N, 5.86%. MS (EI, 70 eV): 239 (Mϩ , 15), 183 (90), 168
ؒ
(87), 124 (81), 57 (100), 41 (69).
tert-Butyl
6-ethyl-5,6-dihydro-4H-thieno[3,2-b]pyrrole-4-
1
carboxylate 10b. Oil. Yield = 67%. H NMR (CDCl3), δ: 7.16,
6.86 (2br s, 1H, H2), 7.02 (d, 1H, H3, J = 4.8 Hz), 4.37–4.30 (m,
1H, H5), 3.88–3.82 (m, 1H, H6), 3.35–3.23 (m, 1H, H5), 1.57 (m,
tert-Butyl {2-[3-acetoxy-2-(phenylselanyl)propyl]-3-thienyl}-
1
carbamate 22a. Oil. Yield = 30%. H NMR (CDCl3), δ: 7.50–
7.48 (m, 2H, Ph), 7.25–7.19 (m, 4H, Ph, H5), 7.05 (d, 1H, H4,
J = 5.5 Hz), 6.60 (br s, 1H, NH), 4.25 (dd, 1H, CH2OAc,
J = 4.7, 11.6 Hz), 4.11 (dd, 1H, CH2OAc, J = 7.7, 11.6 Hz),
3.46–3.40 (m, 1H, CHSePh), 3.17–3.02 (m, 2H, CH2), 2.04 (s,
3H, CH3), 1.43 (s, 9H, CH3). 13C NMR (CDCl3), δ: 170.2 (CO),
152.9 (CO), 134.7, 133.5, 129.2, 128.1 (Ph), 122.4 (C5), 80.0
(C(CH3)3), 65.5 (CH2OAc), 43.9 (CHSePh), 29.2 (CH2), 28.2
(CH3), 20.8 (CH3). Anal. calc. for C20H25NO4SSe: C, 52.86; H,
5.54; N, 3.08; S, 7.05; found: C, 52.78; H, 5.73; N, 3.22; S,
6.97%.
2H, CH2), 1.49 (s, 9H, CH3), 0.94 (t, 3H, CH3, J = 7.4 Hz). 13
C
NMR (CDCl3), δ: 151.2 (CO), 145.0, 144.5 (C3a), 127.4 (C6a),
126.8 (C2), 116.1, 115.7 (C3), 80.5, 79.9 (C(CH3)3), 58.6, 58.1
(C5), 41.0, 40.2 (C6), 28.9 (CH2), 28.2 (CH3), 11.4 (CH3). Anal.
calc. for C13H19NO2S: C, 61.63; H, 7.56; N, 5.53; found: C,
62.09; H, 7.08; N, 5.74%.
tert-Butyl
6-benzyl-5,6-dihydro-4H-thieno[3,2-b]pyrrole-4-
1
carboxylate 10c. Oil. Yield = 85%. H NMR (CDCl3), δ: 7.24–
6.82 (m, 7H, Ph, H3, H2), 4.34–4.10 (m, 1H, H5), 3.95–3.76 (m,
1H, H5), 3.72–3.55 (m, 1H, H6), 2.85–2.60 (m, 2H, CH2), 1.53
(s, 9H, CH3). 13C NMR (CDCl3), δ: 151.1 (CO), 144.4 (C3a),
138.5, 128.8, 128.3, 127.2, 126.4 (CPh, C2, C6a), 115.8 (C3), 80.2
(C(CH3)3), 57.8 (C5), 41.8(CH2), 40.2 (C6), 28.2 (CH3). Anal.
calc. for C18H21NO2S: C, 68.54; H, 6.71; N, 4.44; found: C,
68.18; H, 6.44; N, 4.37%.
PhSeCl addition to the 2-allylthiophene 13a
The carbamate 13a (0.717 g, 3 mmol) in CH2Cl2 was treated
with PhSeCl (0.862 g, 4.5 mmol) in the same solvent (50 ml).
The mixture was stirred overnight and sat. aq. NaCl solution
was added. The organic layer was dried and evaporated. The
chloroselenide 21b was obtained as a mixture with the substrate
13a (21b–13a, 85:15). The chromatographic separation was
unsuccessful.
tert-Butyl 4,5,6,7-tetrahydro-6-methylthieno[3,2-b]pyridine-4-
carboxylate 19. Oil. Yield = 76%. 1H NMR (CDCl3), δ: 7.42 (br
s, 1H, H2), 6.98 (d, 1H, H3, J = 5.5 Hz), 4.00 (m, 1H, H5), 3.06
(dd, 1H, H5, J = 9.7, 12.6 Hz), 2.86 (dd, 1H, H7, J = 5.6, 16.2
Hz), 2.37 (dd, 1H, H7, J = 9.0, 16.2 Hz), 2.22–2.02 (m, 1H, H6),
1.52 (s, 9H, CH3), 0.88 (d, 3H, CH3, J = 7.7 Hz). 13C NMR
(CDCl3), δ: 152.6 (CO), 135.0 (C3a), 123.0 (C2), 121.0 (C6a),
120.3 (C3), 80.4 (C(CH3)3), 49.8 (C5), 31.2 (C7), 28.2 (CH3), 28.1
(C6), 18.1 (CH3). Anal. calc. for C13H19NO2S: C, 61.63; H, 7.56;
N, 5.53; S, 12.65; found: C, 61.47; H, 7.55; N, 5.48; S, 12.65%.
tert-Butyl
{2-[2-chloro-3-(phenylselanyl)propyl]-3-thienyl}-
1
carbamate 21b. H NMR (CDCl3), δ: 7.52–7.47 (m, 2H, Ph),
7.24–7.17 (m, 4H, Ph, H5), 7.06 (d, 1H, H4, J = 5.4 Hz), 6.60 (br
s, 1H, NH), 4.15–4.05 (m, 1H, CHCl), 3.37 (dd, 1H, J = 3.9 H,
15.7 Hz), 3.28 (dd, 1H, J = 4.7, 12.8 Hz), 3.14 (dd, 1H, J = 7.3,
15.7 Hz), 3.11 (dd, 1H, J = 9.3, 12.8 Hz), 1.43 (s, 9H, CH3). 13
C
NMR (CDCl3), δ: 153.1 (CO), 134.0, 133.2, 129.3, 127.7 (Ph),
122.6 (C5), 117.0 (C4), 80.3 (C(CH3)3), 61.8 (CHCl), 34.3 (CH2),
33.7 (CH2), 28.2 (CH3).
tert-Butyl 5,6-dihydro-6,6-dimethyl-4H-thieno[3,2-b]pyrrole-
4-carboxylate 20. Not isolated in a pure form. 1H NMR
(CDCl3), δ: 7.04 (d, 1H, H2, J = 5.1 Hz), 6.85 (d, 1H, H3, J = 5.1
Hz), 3.97 (m, 2H, H5), 1.51 (s, 9H, CH3), 1.36 (s, 6H, CH3).
Cyclization of the ꢀ-chloro phenylselenide 21b
A solution of the crude addition product 21b (0.862 g, 2 mmol)
in CH2Cl2 was stirred overnight in the presence of silica gel
(1 g). After filtration and concentration, the solid was recrystal-
lized. The oxazepine 25 was isolated as white crystals. The
solution resulting from the recrystallization was evaporated and
chromatographed (eluent: CH2Cl2–light petroleum, 50:50).
The dihydrothienopyrrole 23, tetrahydrothienopyridine 24 and
thienooxazepine 25 were successively isolated in 25, 5 and 21%
yields respectively.
Preparation of tert-butyl 2-allyl-3-thienylcarbamate 13a16
The carbamate 3a (0.398 g, 2 mmol) in THF (20 ml) was treated
with n-BuLi (2.5 M solution in hexane, 2 ml) at Ϫ78 ЊC. Allyl
bromide (0.423 g, 3 mmol) was added at Ϫ10 ЊC. The mixture
was stirred for 2 h at this temperature and quenched with sat.
aq. NaCl solution. The organic layer was evaporated and the
product 13a was purified by silica gel chromatography (eluent:
1
light petroleum–CH2Cl2, 50:50). Mp = 70 ЊC, yield = 95%. H
NMR (CDCl3), δ: 7.30 (br s, 2H, H5), 7.02 (d, 1H, H4, J = 5.4
Hz), 6.50 (br s, 1H, NH), 5.80 (m, 1H, Hβ), 5.07 (m, 2H, Hγ),
3.40 (d, 2H, Hα, J = 6.5 Hz).
tert-Butyl
5,6-dihydro-5-(phenylselanylmethyl)-4H-thieno-
[3,2-b]pyrrole-4-carboxylate 23. Oil. Yield = 25%. 1H NMR
(CDCl3), δ: 7.46–7.44 (m, 2H, Ph), 7.30 (br s, 1H, H2), 7.21–7.19
J. Chem. Soc., Perkin Trans. 1, 2001, 37–43
41

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(m, 3H, Ph), 6.97 (d, 1H, H3, J = 5.4 Hz), 3.73–3.83 (m, 1H,
H5), 3.05–2.73 (m, 4H, H6, CH2), 1.42 (s, 9H, CH3). 13C NMR
(CDCl3), δ: 153.4 (CO), 134.5, 133.3, 129.2, 127.5 (Ph), 121.5
(C2), 110.3 (C3), 71.0 (C5), 35.5 (CH2), 32.9 (CH2), 28.3 (CH3).
Anal. calc. for C18H21NO2SSe: C, 54.82; H, 5.37; N, 3.55; S,
8.13; found: C, 54.51; H, 5.56; N, 3.79; S, 7.97%.
6.14 (d, 1H, H5, J = 3.4 Hz), 6.00–5.80 (m, 1H, Hβ), 5.27–5.11
(m, 2H, Hγ), 4.09 (d, 2H, Hα, J = 5.7 Hz), 3.57 (br s, 2H, NH2),
1.44 (s, 9H, CH3). 13C NMR (CDCl3), δ: 154.0 (CO), 141.2 (C3),
133.7 (C4), 133.2 (Cβ), 117.8 (C2), 116.6 (Cγ), 99.8 (C5), 80.5
(C(CH3)3), 52.9 (Cα), 27.9 (CH3). Anal. calc. for C12H18N2O2S:
C, 56.67; H, 7.13; N, 11.01; found: C, 56.77; H, 7.02; N, 10.53%.
tert-Butyl 4,5,6,7-tetrahydro-6-(phenylselanyl)thieno[3,2-b]-
Reaction of N-allyl compounds 14a, 18 and 27 with PhSeCl
1
pyridine-4-carboxylate 24. Oil. Yield = 5%. H NMR (CDCl3),
δ: 7.50–7.48 (m, 2H, Ph), 7.31 (br s, 1H, H2), 7.21–7.19 (m, 3H,
Ph), 7.03 (d, 1H, H3, J = 5.2 Hz), 3.52 (m, 2H, H5), 3.41–3.37
(m, 1H, H6), 3.11–3.08 (m, 2H, H7), 1.42 (s, 9H, CH3). 13C
NMR (CDCl3), δ: 154.0 (CO), 134.8, 129.2, 128.1 (Ph), 62.0
(C5), 48.8 (C6), 28.3 (C7), 28.2 (CH3). Anal. calc. for
C18H21NO2SSe: C, 54.82; H, 5.37; N, 3.55; S, 8.13; found: C,
54.86; H, 5.71; N, 3.19; S, 7.92%.
N-Allylthienylcarbamate 14a (0.478 g, 2 mmol) in CH2Cl2 (30
ml) was treated with PhSeCl (0.575 g, 3 mmol) dissolved in the
same solvent (30 ml) containing sodium carbonate (0.848 g,
8 mmol). The reaction mixture was stirred overnight and sat.
aq. NaCl solution was added. The organic layer was dried and
evaporated. Silica gel chromatography afforded the oxazo-
lidinone 28 (eluent: CH2Cl2). The same procedure gave the
bis(oxazolidinone) 29a from dicarbamate 18 and the 2-(phenyl-
selanyl)thiophene derivative 30 from the monoallyl diamine
derivative 27. The chromatographic purification was achieved
on silica gel (eluent: light petroleum–CH2Cl2, 50:50).
4,5,7,8-Tetrahydro-5-oxo-7-(phenylselanylmethyl)thieno[3,2-
d][1,3]oxazepine 25. Mp = 151 ЊC, yield = 21%. 1H NMR
(CDCl3), δ: 8.67 (br s, 1H, NH), 7.49–7.46 (m, 2H, Ph), 7.23–
7.19 (m, 3H, Ph), 6.98 (d, 1H, H2, J = 5.3 Hz), 6.57 (d, 1H, H3,
J = 5.3 Hz), 4.66–4.63 (m, 1H), 3.35–3.25 (m, 2H, CH2), 3.12–
3.03 (m, 2H, CH2). 13C NMR (CDCl3), δ: 156.2 (CO), 133.4,
131.6, 129.3, 127.6 (Ph), 121.4 (C2), 117.0 (C3), 78.4 (C7), 33.0
(CH2), 31.4 (CH2). Anal. calc. for C14H13NO2SSe: C, 49.71; H,
3.87; N, 4.14; S, 9.48; found: C, 49.40; H, 4.16; N, 3.69; S,
5-(Phenylselanylmethyl)-3-(3-thienyl)-1,3-oxazolidin-2-one
1
28. Oil. Yield = 58%. H NMR (CDCl3), δ: 7.51–7.50 (m, 2H,
Ph), 7.32–7.29 (m, 5H, Ph, H4Ј, H5Ј), 6.87 (s, 1H, H2Ј), 4.71–4.64
(m, 1H, H5), 4.00 (t, 1H, H4, J = 8.8 Hz), 3.66 (dd, 1H, H4,
J = 8.8, 6.3 Hz), 3.27 (dd, 1H, CH2Se, J = 4.3, 12.9 Hz), 2.97
(dd, 1H, CH2Se, J = 9.2, 12.9 Hz). 13C NMR (CDCl3), δ: 153.8
(C2), 136.4 (C3Ј), 133.4, 129.3, 127.9 (Ph), 125.4 (C4Ј), 119.4
(C5Ј), 107.2 (C2Ј) 72.1 (C5), 51.5 (C4), 30.9 (CH2Se). Anal. calc.
for C14H13NO2SSe: C, 49.71; H, 3.87; N, 4.14; S, 9.48; found: C,
49.98; H, 3.87; N, 4.52; S, 9.58%.
9.18%. MS (EI, 70 eV): 339 (Mϩ , 18), 314 (58), 182 (50), 157
ؒ
(81), 136 (100), 124 (82), 77 (82).
N-Allylation of the amino carbamate 4 and dicarbamate 5
A mixture of amino carbamate 4 (0.214 g, 1 mmol) and NaH
(0.24 g, 10 mmol) in THF (20 ml) was stirred for 30 min. Allyl
bromide (1.21 g, 10 mmol) was added and the stirring con-
tinued for 5 h. The mixture was quenched at 0 ЊC with sat. aq.
NaCl solution. The organic layer was evaporated and silica
gel chromatography provided the monoallylated product 27
(eluent: light petroleum–CH2Cl2, 50:50). The diallylated dicarb-
amate 18 was prepared from dicarbamate 5 using double
amounts of NaH and allyl bromide, after 5 h of stirring at room
temperature. The diallyl thienoimidazolone 26 was obtained
after 20 h of reaction. All compounds were purified by silica gel
chromatography (eluent: light petroleum–CH2Cl2, 50:50).
3,4-Bis[2-oxo-5-(phenylselanylmethyl)-1,3-oxazolidin-3-yl]-
thiophene 29a. Yield = 45%. 1H NMR (CDCl3), δ: 7.48–7.46 (m,
4H, Ph), 7.22–7.19 (m, 6H, Ph), 7.03 (s, 2H, H2, H5), 4.66–4.61
(m, 2H, H5Ј), 4.02 (t, 2H, H4Ј, J = 8.6 Hz), 3.75–3.67 (m, 2H,
H4Ј), 3.27 (dd, 2H, CH2Se, J = 3.4, 12.8 Hz), 3.08–3.00 (m,
2H, CH2Se). 13C NMR (CDCl3), δ: 155.2 (C2Ј), 133.3, 132.0,
129.3, 127.8 (Ph), 128.0 (C4), 119.2 (C5), 73.1 (C5Ј), 52.5 (C4Ј),
30.7 (CH2Se). Anal. calc. for C24H22N2O4SSe2: C, 48.66; H,
3.74; N, 4.73; S, 5.41; found: C, 48.98; H, 3.72; N, 4.97; S,
5.02%.
tert-Butyl N-allyl-3-thienylcarbamate 14a.16 Oil. Yield = 51%.
1H NMR (CDCl3), δ: 7.13 (m, 1H, H5), 7.07 (m, 1H, H4), 6.97
(m, 1H, H2), 6.00–5.80 (m, 1H, Hβ), 5.27–5.11 (m, 2H, Hγ), 4.09
(d, 2H, Hα, J = 5.7 Hz), 1.44 (s, 9H, CH3). 13C NMR (CDCl3),
δ: 154.0 (CO), 127.5, 126.5, 124.6, 123.5, 113.1 (Cγ), 51.4 (Cα),
28.2.
tert-Butyl N-allyl[5-(phenylselanyl)-4-amino-3-thienyl]carb-
amate 30. Oil. Yield = 76%. 1H NMR (CDCl3), δ: 7.59–7.55 (m,
2H, Ph), 7.23–7.19 (m, 3H, Ph), 7.12 (s, 1H, H2), 5.96–5.78 (m,
1H, Hβ), 5.19–5.08 (m, 2H, Hγ), 3.91–4.11 (m, 4H, Hα, NH2),
1.43 (s, 9H, CH3). 13C NMR (CDCl3), δ: 153.9 (CO), 147.1 (C4),
133.7 (C3), 133.4, 129.0, 127.8, 125.9 (Ph), 132.9 (Hβ), 117.3
(Hγ), 53.6 (Hα), 80.8 (C(CH3)3), 28.1 (CH3). Anal. calc. for
C18H22N2O2SSe: C, 52.81; H, 5.42; N, 6.84; found: C, 53.00; H,
5.64; N, 6.42%.
Di-tert-Butyl N,NЈ-diallylthiophene-3,4-diyldicarbamate 18.
Oil. Yield = 85%. 1H NMR (CDCl3), δ: 7.00 (br s, 2H, H2, H6),
5.98–5.84 (m, 2H, Hβ), 5.17–5.09 (m, 4H, Hγ), 3.98 (d, 4H, Hα,
J = 5.7 Hz), 1.41 (s, 18H, CH3). 13C NMR (CDCl3), δ: 154.1
(CO), 134.0 (Cβ), 131.7 (C3, C4), 118.0 (C2, C5), 116.4 (Cγ), 80.1
N-Iodosuccinimide-induced cyclization of di-tert-butyl N,NЈ-
diallyl(thiophene-3,4-diyl)dicarbamate 18
(C(CH3)3), 44.7 (Cα), 28.1 (CH3). MS (EI, 70 eV): 294 (Mϩ , 2),
ؒ
NIS (0.9 g, 4 mmol) was added to N,NЈ-diallyldicarbamate 18
(0.394 g, 1 mmol) in CCl4 (20 ml). The mixture was stirred
overnight at room temperature. The oxazolidinone 29b was
isolated and purified as described for 29a.
238 (6), 194 (4), 165 (63), 57 (100), 41 (60).
N,NЈ-Diallyl-2-oxo-2,3-dihydro-1H-thieno[3,4-d]imidazole
26. Oil. Yield = 67%. 1H NMR (CDCl3), δ: 6.24 (s, 2H, H4, H6),
5.97–5.77 (m, 2H, Hβ), 5.32–5.20 (m, 4H, Hγ), 4.36 (m, 4H, Hα).
13C NMR (CDCl3), δ: 217.8 (CO), 131.7 (Cβ), 131.6 (C2a, C2b),
116.0 (Cγ), 93.8 (C3a, C6a), 44.7 (Cα). Anal. calc. for C11H12N2OS:
C, 59.98; H, 5.49; N, 12.72; found: C, 60.14; H, 5.98; N, 12.98%.
IR (KBr): 3102, 2980, 2916, 1713, 1645, 1552 cmϪ1. MS (EI, 70
3,4-Bis(5-iodomethyl-2-oxo-1,3-oxazolidin-3-yl)thiophene
29b. Yield = 37%. 1H NMR (CDCl3), δ: 7.19 (s, 1H, H2), 7.18 (s,
1H, H5), 4.80–4.61 (m, 2H, H5Ј), 4.16 (t, 2H, H4Ј, J = 8.7 Hz),
3.83–3.74 (m, 2H, H4Ј), 3.42 (d, 4H, CH2I, J = 6.4 Hz). Anal.
calc. for C12H12I2N2O4S: C, 26.99; H, 2.26; N, 5.24; found: C,
eV): 220 (Mϩ , 100), 187 (26), 179 (25), 151 (63), 136 (22), 123
ؒ
27.42; H, 2.35; N, 5.63%. MS (EI, 70 eV): 534 (Mϩ , 17), 406
ؒ
(30), 80 (39), 41 (80), 39 (78).
(30), 363 (100), 254 (75), 235 (27), 144 (50), 127 (53). MS
(desorption chemical ionisation, DCI, pos., isobutane): 585
((MH ϩ C4H9)ϩ, 100), 365 (45), 100 (43).
tert-Butyl N-allyl(4-amino-3-thienyl)carbamate 27. Oil.
Yield = 51%. 1H NMR (CDCl3), δ: 6.90 (d, 1H, H2, J = 3.4 Hz),
42
J. Chem. Soc., Perkin Trans. 1, 2001, 37–43

View Online
6 C. Galvez, F. Garcia, A. Marzal and P. Viladoms, J. Chem. Res.,
Preparation of N,NЈ-diallyl-3,4-bis(methylamino)thiophene 32
1994, 12; D. N. Reinhoudt, J. Geevers, W. P. Trompenaars, S.
Harkema and G. J. Van Hummel, J. Org. Chem., 1981, 46, 424.
7 (a) F. Outurquin and C. Paulmier, Bull. Soc. Chim. Fr., 1983, II, 153;
F. Outurquin and C. Paulmier, Bull. Soc. Chim. Fr., 1983, II, 159; (b)
F. Outurquin, P. Lerouge and C. Paulmier, Bull. Soc. Chim. Fr.,
1986, 259; F. Outurquin, P. Lerouge and C. Paulmier, Bull.
Soc. Chim. Fr., 1986, 267; (c) F. Outurquin and C. Paulmier, Tetra-
hedron Lett., 1993, 34, 5715. (d) M. Berkaoui, F. Outurquin and
C. Paulmier, J. Heterocycl. Chem., 1996, 33, 9; (e) D. Brugier,
F. Outurquin and C. Paulmier, Tetrahedron, 1997, 53, 10331.
8 D. Brugier, F. Outurquin and C. Paulmier, Tetrahedron, 2000, 56,
2985.
Dicarbamate 18 (0.394 g, 1 mmol) in dry ether (30 ml) was
added to a suspension of LiAlH4 (0.8 g, 20 mmol) in the same
solvent (20 ml). The mixture was stirred overnight, cooled to
0 ЊC and treated with sat. aq. NaCl. The aqueous solution was
extracted twice with ether and the combined organic layers were
dried and evaporated. Silica gel chromatography (eluent: light
petroleum–CH2Cl2, 80:20) afforded the diamine 32. Yield:
1
72%. H NMR (CDCl3), δ: 6.31 (s, 2H, H2, H5), 5.92–5.75 (m,
2H, Hβ), 5.25–5.12 (m, 4H, Hγ), 3.75 (d, 4H, Hα, J = 6.3 Hz),
2.68 (s, 6H, CH3). 13C NMR (CDCl3), δ: 145.2 (C3, C4), 135.3
(Cβ), 116.9 (Cγ), 104.7 (C2, C5), 56.1 (Cα), 39.0 (CH3). Anal.
calc. for C12H18N2S: C, 64.82; H, 8.16; N, 12.60; found: C,
64.97; H, 8.22; N, 12.77%.
9 M. S. Yu, L. Lopez de Leon, M. A. McGuire and G. Bothon,
Tetrahedron Lett., 1998, 39, 9347; S. Cacchi, G. Fabrizi, F. Marinelli,
L. Moro and P. Pace, Synlett, 1997, 1363; S. Cacchi, G. Fabrizi and
P. Pace, J. Org. Chem., 1998, 63, 1001.
10 J. Fujiwara, Y. Fukutani, H. Sano, K. Maruoka and H. Yamamoto,
J. Am. Chem. Soc., 1983, 105, 7177; T. Nishikawa, M. Ishikawa and
M. Isobe, Synlett, 1999, 123.
Acknowledgement
11 Y. Kondo, S. Kojima and T. Sakamoto, Heterocycles, 1996, 43, 2741.
12 (a) W. F. Bailey and X. L. Jiang, J. Org. Chem., 1996, 61, 2596; (b)
D. Zhang and L. S. Liebeskind, J. Org. Chem., 1996, 61, 2594.
13 For the preparation of indolines via radical cyclization of N-allyl-
anilines see: D. L. Boger, R. M. Garbaccio and Q. Jin, J. Org. Chem.,
1997, 62, 8875; J. Inanaga, O. Ujikawa and M. Yamaguchi,
Tetrahedron Lett., 1991, 32, 1737; Y. Hayashi, H. Shinokubo and
K. Oshima, Tetrahedron Lett., 1998, 39, 63; J. Nakao, R. Inoue,
H. Shinokubo and K. Oshima, J. Org. Chem., 1997, 62, 1910.
14 D. L. Clive, V. Farina, A. Singh, C. K. Wong, W. A. Kiel and S. M.
Menchen, J. Org. Chem., 1980, 45, 2120; K. C. Nicolaou, D. A.
Claremon, W. E. Barnette and S. P. Seitz, J. Am. Chem. Soc., 1979,
103, 3703; R. R. Weeb and S. Danishefsky, Tetrahedron Lett., 1983,
24, 1357.
We thank the “Conseil Régional de Haute-Normandie” for the
provision of a grant (D. B.).
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