Practical synthesis of chiral β-telluro amines by ring-opening reaction of aziridines

Article abstract of DOI:10.1016/j.jorganchem.2008.09.025

A set of chiral β-tellurium amines and their selenium and sulfur-containing derivatives have been efficiently synthesized in good to excellent yields via the ring-opening reaction of chiral aziridines by chalcogen nucleophilic species.

Full text of DOI:10.1016/j.jorganchem.2008.09.025

Journal of Organometallic Chemistry 694 (2009) 122–126
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Journal of Organometallic Chemistry
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Note
Practical synthesis of chiral b-telluro amines by ring-opening reaction of aziridines
*
Fabricio Vargas , João V. Comasseto
Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, 05508-900 São Paulo SP, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
A set of chiral b-tellurium amines and their selenium and sulfur-containing derivatives have been effi-
ciently synthesized in good to excellent yields via the ring-opening reaction of chiral aziridines by chal-
cogen nucleophilic species.
Received 15 August 2008
Received in revised form 23 September
2008
Accepted 23 September 2008
Available online 27 September 2008
Ó 2008 Elsevier B.V. All rights reserved.
Keywords:
Tellurium
Ring-opening reaction
Aziridines
Chiral
1. Introduction
ophiles, resulting in interesting b-substituted nitrogenated
compounds [16–20].
Organotellurium chemistry is a very broad and exciting field
with many opportunities for research and development of applica-
tions in organic synthesis [1,2]. Many different classes of organo-
tellurium compounds have been prepared to date, and vinylic
tellurides are certainly the most extensively studied ones, in view
of their usefulness in a wide range of applications in organic syn-
thesis [3] and in the total synthesis of natural products [4–6]. In
addition to their utility in this field, the toxicological and pharma-
cological aspects of organotellurium compounds have also been re-
cently reviewed [7].
In this way, following our current interest in the development
and application of functionalized organotellurium compounds in
organic synthesis [8–12], we report herein the preparation of a
modular series of nitrogen-containing organotellurium compounds
and their selenium and sulfur analogues via the ring-opening reac-
tion of easily available aziridines, as depicted in Fig. 1.
2. Results and discussion
Aiming to evaluate the performance of tellurium nucleophiles
in the ring-opening reaction, aziridine 1a was chosen as a model
substrate, in order to determine the optimum conditions for the
present study. Initially, the process was carried out in the presence
of [BuTeH], easily gererated in situ by reaction of elemental tellu-
rium and n-BuLi in THF and EtOH as a proton source. Under these
conditions, the tellurium atom was efficiently introduced by
regioselective nucleophilic ring-opening at the less hindered car-
bon of aziridine 1a, furnishing the b-telluro amine 2a in 89% yield
(Scheme 1, conditions A). The reaction was also performed in the
presence of butyltellurolate anion, generated by reduction of
BuTeTeBu with NaBH4 in EtOH. However, no improvement could
be observed, since the corresponding product 2a was obtained in
lower yield and after a longer reaction time (Scheme 1, conditions
B). The reaction was also studied in the presence of BuTeMgBr as a
nucleophilic source of tellurium. However, only traces of the corre-
sponding product, starting aziridine 1a and dibutyl ditelluride as
by-product were observed in the present reaction (Scheme 1, con-
ditions C).
Among the several classes of organotellurium compounds the
functionalized alkyl tellurides are still scarcely studied. Recently,
our research group has been working in the preparation and appli-
cation of hydroxy tellurides in the tellurium/lithium exchange
reaction. These compounds have been efficiently used as alterna-
tive organometallic sources of 1,4-dianion intermediates in the
synthesis of diols [8], spiroketals [9], bioactive butenolides [10],
and in the synthesis of natural products, such as ( )-frontalin
[11] and (+)-endo-brevicomin [12]. The interesting results obtained
with oxygen-containing organotellurium compounds served as
inspiration for the design and application of many other function-
alized organotellurium compounds.
On the other hand, aziridines, biologically relevant heterocycles
widely found in natural products [13,14], represent a versatile and
useful class of nitrogen-containing compounds in organic transfor-
mations [15], exemplified by the ring-opening reaction with nucle-
* Corresponding author. Tel.: +55 11 3091 1180; fax: +55 11 3815 5579.
E-mail address: fvargas@iq.usp.br (F. Vargas).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.09.025

F. Vargas, J.V. Comasseto / Journal of Organometallic Chemistry 694 (2009) 122–126
123
R1
Condition
R1
TeBu
NHBoc
2a
TeR
NHPG
N
Boc
r. t.
+
RTe
N
PG
1a
β
-telluro amine
Conditions A:
n-BuLi/Te°, THF/EtOH, 2 h
89%
Fig. 1. Retrosynthetic analysis of the chiral b-telluro amines.
Conditions B: BuTeTeBu/NaBH4, EtOH, 3h
Conditions C: BuTeMgBr, THF, 24 h
81%
traces
Scheme 1. Ring-opening reaction of aziridine 1a.
Table 1
Preparation of chiral b-telluro amines by ring-opening reaction of aziridines
R1
R1
[RTeLi], THF
TeR
NHPG
N
PG
EtOH, r. t.
2 h
2a-h
1a-f
Entry
1
Aziridine
RTeLi
Product
Yielda (%)
89
BuTeLi
TeBu
NHBoc
N
Boc
2a
1a
2
1a
1a
2-ThTeLi
74
S
Te
NHBoc
2b
TePh
NHBoc
3
4
PhTeLi
BuTeLi
80
79
2c
TeBu
N
Ts
NHTs
2d
1b
5
BuTeLi
81
TeBu
NHTs
N
Ts
1c
2e
6
7
BuTeLi
BuTeLi
BuTeLi
78
84
83
TeBu
NHTs
N
Ts
1d
2f
TeBu
NHTs
N
Ts
1e
2g
8
TeBu
N
Ts
1f
NHTs
2h
a
Isolated yield of the corresponding product.

124
F. Vargas, J.V. Comasseto / Journal of Organometallic Chemistry 694 (2009) 122–126
concerning the tellurium/lithium exchange reaction of the nitro-
gen-containing tellurium compounds prepared herein and the re-
sults will be reported in due course.
[BuYLi], THF
YBu
NHBoc
N
Boc
EtOH, r.t.
2 h
2i Y = Se, 78%
2j Y = S, 72%
4. Experimental
4.1. General
Scheme 2. Ring-opening reaction of aziridine 1a with selenium and sulfur
nucleophiles.
Elemental tellurium, selenium and sulfur (200 mesh) were pur-
chased from Sigma Aldrich. All reagents and solvents were purified
and dried using procedures described in the literature [26]. THF
was distilled under nitrogen from sodium/benzophenone just be-
fore use. N-Butyllithium was titrated using 1,10-phenanthroline
as indicator prior to use. All operations were carried out in
flame-dried glassware. Column chromatographic separations were
performed over Acros Organics silica gel (0.035–0.075 mm; pore
diameter ca. 6 nm). The melting points were determined using a
Büchi, model B-545. Optical rotations were determined on a Perkin
Elmer 343 polarimeter and IR spectra were recorded on a Bomem
MB-100 spectrophotometer. NMR spectra were recorded on Var-
ian-Inova (300 MHz, 1H; 75 MHz, 13C) or Bruker model DRX-500
(500 MHz, 1H; 125 MHz, 13C) spectrometers using CDCl3 as solvent.
The internal references were TMS (1H NMR), the central peak of the
CDCl3 signal (13C NMR), a capillary of diphenyl ditelluride 1 molꢀ1
After determining the best procedure for generating the nucle-
ophilic source of tellurium and the appropriated solvent, the ring-
opening process was further expanded to a broader range of
aziridines and tellurium anions in order to evaluate its scope and
limitations (Table 1).
As can be seen, all the b-telluro amines were obtained in good to
excellent yields from different aziridines. The ring-opening process
of N-Boc aziridine 1a was also evaluated in the presence of organo-
tellurium species attached to heteroarylic and arylic groups (Table
1, entries 2 and 3), furnishing the corresponding products 2b and
2c in 74% and 80% yields, respectively. The ring-opening reaction
was also performed in the presence of aziridines bearing a tosyl
group (PG = Ts) instead of a t-butoxycarbonyl group (PG = Boc) as
well as different lipophilic substituents (R1 = Bn, i-Pr, i-Bu, Me).
In these cases, the corresponding products 2d–g were obtained
in up to 84% yield (Table 1, entries 4–7). A very simple b-tellurium
amine 2h was also prepared in 83% yield via the ring-opening reac-
tion of N-Ts aziridine (Table 1, entry 8).
The successful ring-opening procedure with n-BuLi and elemen-
tal tellurium was also evaluated in the presence of aziridines with
R1 = Bn and containing N-benzoyl (PG = Bz) and N-benzyloxycar-
bonyl (PG = Cbz) protecting groups. However, in both cases, only
traces of the corresponding products were observed, the starting
material was recovered and dibutyl ditelluride was detected as
by-product.
(
125Te NMR) and a capillary of diphenyl diselenide 1 molꢀ1 77Se
(
NMR). High resolution mass spectroscopy was performed using a
LC–MS – Bruker Daltonics instrument at the Microanalytical Labo-
ratory of the Institute of Chemistry, University of São Paulo. Aziri-
dines 1a [27], 1b–e [28] and 1f [29] were prepared according to the
procedures described in the literature.
4.2. (S)-tert-Butyl 1-(butyltellanyl)-3-phenylpropan-2-ylcarbamate
(2a)
n-Butyllithium (1 mmol, 1.5 M in hexane) was slowly added at
At this point, it is important to emphasize that all organotellu-
rium compounds described herein are very stable to the ambient
light and can be stored and manipulated in the air. Most of them
are almost odorless or present a smell not more unpleasant them
most chemicals normally used in an organic synthesis laboratory.
Chiral organoselenium and organosulfur compounds containing
nitrogen also represent important classes of compounds in organic
synthesis. Among several applications, these compounds are useful
chiral ligands in asymmetric catalysis [21,22]. In this way, the ring-
opening reaction of aziridine 1a was also evaluated in the presence
of organochalcogen species containing selenium and sulfur. This
process is already described in the literature [23–25]. However,
in most cases, the nucleophilic species are obtained from the cor-
responding dichalcogenides which are transformed in situ into
organochalcogenolates or organochalcogenols, or by using the
bad smelling commercially available thiols. Thus, using a similar
procedure described for the preparation of the organotellurium
compounds 2a–h, the desired organoselenium 2i and organosulfur
2j compounds were obtained in 78% and 72% yields, via the in situ
generation of [BuSeLi] and [BuSLi], respectively (Scheme 2). In this
way, we avoided the preparation of the corresponding dichalcoge-
nides as well as the use of the corresponding thiol.
room temperature to
a suspension of elemental tellurium
(1.2 mmol) in dry THF (5 mL). Deoxygenated ethanol (2 mL) was
added to the light yellow solution of lithium butyl tellurolate so
formed, and the resulting red-brown mixture was stirred at room
temperature for 10 min and subsequently cooled to 0 °C. The aziri-
dine 1a (1 mmol) was added in a single portion, and the resulting
mixture was stirred for 2 h at room temperature. The mixture was
quenched with a saturated NH4Cl solution and extracted with
CH2Cl2, and the combined organic fractions were collected, dried
over MgSO4, and filtered. The solvent was removed in vacuo, yield-
ing the crude product 2a, which was purified by flash chromatog-
raphy. Yield: 89%; white solid; m.p.: 69.4–71.4 °C; ½a D24
¼ þ13:2
ꢁ
(c = 1.0, CH2Cl2); IR (KBr) 3364, 2959, 2926, 1688, 1516,
1166 cmꢀ1 1H NMR (CDCl3, 500 MHz) d 7.30–7.27 (m, 2H), 7.23–
;
7.17 (m, 3H), 4.70 (br s, 1H), 3.91 (br s, 1H), 2.86–2.74 (m, 4H),
2.63 (t, J = 7.5 Hz, 2H), 1.68 (qui, J = 7.5 Hz, 2H), 1.41 (s, 9H), 1.35
(sex, J = 7.5 Hz, 2H), 0.90 (t, J = 7.5 Hz, 3H); 13C NMR (CDCl3,
75 MHz) d 155.0, 137.7, 129.3, 128.4, 126.5, 79.3, 51.8, 41.9, 34.2,
28.3, 25.0, 13.4, 10.2, 3.7; 125Te NMR (CDCl3, 157 MHz) d 121.4;
HRMS-ESI m/z calculated for C18H29NO2Te + Na+ 441.1158, found
441.1155.
4.3. (S)-tert-Butyl 1-phenyl-3-(thiophen-2-yltellanyl)propan-2-
ylcarbamate (2b)
3. Conclusion
n-Butyllithium (2 mmol, 1.5 M in hexane) was slowly added to
a solution of thiopene (2 mmol) in dry THF (6 mL) at ꢀ78 °C. The
reaction mixture was then stirred for 30 min at this temperature
and allowed to warm to ꢀ40 °C and elemental tellurium (2 mmol)
was added in one portion and the reaction mixture was stirred for
In summary, we have described a practical and concise synthe-
sis of structurally diverse b-tellurium amines and their selenium
and sulfur analogues in good to excellent yields via the ring-open-
ing reaction of aziridines by a straightforward and flexible syn-
thetic route. Further studies are in progress in our laboratory

F. Vargas, J.V. Comasseto / Journal of Organometallic Chemistry 694 (2009) 122–126
125
an additional 1 h at this temperature. Deoxygenated ethanol
(3 mL) was added to the light yellow solution of lithium thiophen
tellurolate so formed, and the resulting red-brown mixture was
stirred at room temperature for 10 min and subsequently cooled
to 0 °C. The aziridine 1a (1 mmol) was added in a single portion,
and the resulting mixture was stirred for 2 h at room temperature.
The mixture was quenched with a saturated NH4Cl solution and
extracted with CH2Cl2, and the combined organic fractions were
collected, dried over MgSO4, and filtered. The solvent was removed
in vacuo, yielding the crude product 2b, which was purified by
flash chromatography. Yield: 74%; yellow solid; m.p.: 85.4–
32.3, 24.9, 21.5, 19.3, 17.5, 13.3, 8.9, 4.0; 125Te NMR (CDCl3,
157 MHz) d 132.0; HRMS-ESI m/z calculated for C16H27NO2STe + -
Na+ 450.0722, found 450.0718.
4.7. (S)-N-(1-(Butyltellanyl)-4-methylpentan-2-yl)-4-
methylbenzenesulfonamide (2f)
The b-telluroamine 2f was prepared according to the procedure
described to b-telluroamine 2a, however aziridine 1d was used in-
stead of aziridine 1a. Yield: 78%; yellow oil; ½a D24
¼ ꢀ8:8 (c = 1.0,
ꢁ
CH2Cl2); IR (film) 3275, 2957, 2927, 2870, 1329, 1158,
87.4 °C; ½a 2D4
ꢁ
¼ þ20:4 (c = 1.0, CH2Cl2); IR (KBr) 3371, 2973, 1690,
1092 cmꢀ1 1H NMR (CDCl3, 500 MHz) d 7.78–7.75 (m, 2H), 7.30–
;
1523, 1169, 701 cmꢀ1
;
1H NMR (CDCl3, 500 MHz) d 7.42 (dd,
7.28 (m, 2H), 5.06–5.04 (d, J = 8.5 Hz, 1H), 3.36–3.30 (m, 1H),
2.79 (dd, J = 12.5 Hz, J = 3.5 Hz, 1H), 2.58 (dd, J = 12.5 Hz, J = 6.5
Hz, 1H), 2.50 (t, J = 7.0 Hz, 2H), 2.41 (s, 3H), 1.62 (qui, J = 7.0 Hz,
2H), 1.57–1.49 (m, 1H), 1.32 (sex, J = 7.0 Hz, 2H), 1.26–1.22 (m,
2H), 0.89 (t, J = 7.0 Hz, 3H), 0.80 (d, J = 7.0 Hz, 3H), 0.69 (d,
J = 7.0 Hz, 3H); 13C NMR (CDCl3, 125 MHz) d 143.2, 138.2, 129.6,
127.0, 52.0, 45.6, 34.1, 24.9, 24.4, 22.8, 21.7, 21.4, 13.3, 12.7, 4.1;
125Te NMR (CDCl3, 157 MHz) d 113.5; HRMS-ESI m/z calculated
for C17H29NO2STe + Na+ 464.0879, found 464.0875.
J = 5.5 Hz, J = 1.5 Hz, 1H), 7.40 (dd, J = 3.5 Hz, J = 1.5 Hz, 1H), 7.31–
7.19 (m, 3H), 7.11–7.09 (m, 2H), 6.93 (dd, J = 5.5 Hz, J = 3.5 Hz,
1H), 4.62 (br s, 1H), 4.00 (br s, 1H), 3.00–2.88 (m, 3H), 2.82–2.78
(m, 1H), 1.39 (s, 9H); 13C NMR (CDCl3, 125 MHz) d 154.9, 141.6,
137.5, 134.4, 129.3, 128.7, 128.5, 126.5, 97.4, 79.4, 52.0, 41.0,
28.3, 18.5; 125Te NMR (CDCl3, 157 MHz) d 248.3; HRMS-ESI m/z cal-
culated for C18H23NO2STe + Na+ 470.0409, found 470.0406.
4.4. (S)-tert-Butyl 1-phenyl-3-(phenyltellanyl)propan-2-ylcarbamate
(2c)
4.8. (S)-N-(1-(Butyltellanyl)propan-2-yl)-4-
methylbenzenesulfonamide (2g)
The b-telluroamine 2c was prepared according to the procedure
described to b-telluroamine 2a, however PhLi was used instead of
The b-telluroamine 2g was prepared according to the procedure
described to b-telluroamine 2a, however aziridine 1e was used in-
n-BuLi. Yield: 80%; white solid; m.p.: 81.7–83.7 °C; ½a D24
¼ þ16:1 (c
ꢁ
= 1.0, CH2Cl2); IR (KBr) 3364, 2976, 1687, 1516, 1248, 1165,
stead of aziridine 1a. Yield: 84%; yellow oil; ½a D24
ꢁ
¼ þ3:3 (c = 1.0,
728 cmꢀ1
;
1H NMR (CDCl3, 300 MHz) d 7.73–7.70 (m, 2H), 7.27–
CH2Cl2); IR (film) 3271, 2958, 2870, 1326, 1158, 1093 cmꢀ1 1H
;
7.09 (m, 8H), 4.67–4.65 (m, 1H), 4.05–4.03 (m, 1H), 3.09–3.02
(m, 2H), 2.87–2.78 (m, 2H), 1.37 (s, 9H); 13C NMR (CDCl3,
75 MHz) d 154.9, 138.5, 137.5, 129.3, 129.2, 128.4, 127.7, 126.5,
111.4, 79.3, 52.0, 42.0, 28.3, 16.0; 125Te NMR (CDCl3, 157 MHz) d
372.8; HRMS-ESI m/z calculated for C20H25NO2Te + Na+ 464.0845,
found 464.0844.
NMR (CDCl3, 500 MHz) d 7.78–7.75 (m, 2H), 7.31–7.27 (m, 2H),
4.93–4.91 (br s, 1H), 3.43–3.41 (br s, 1H), 2.75 (dd, J = 12.5 Hz,
J = 4.5 Hz, 1H), 2.65 (dd, J = 12.5 Hz, J = 6.5 Hz, 1H), 2.52 (t,
J = 7.0 Hz, 2H), 2.42 (s, 3H), 1.63 (qui, J = 7.0 Hz, 2H), 1.33 (sex,
J = 7.0 Hz, 2H), 1.12 (d, J = 6.5 Hz, 3H), 0.89 (t, J = 7.0 Hz, 3H); 13C
NMR (CDCl3, 125 MHz) d 143.3, 137.9, 129.6, 127.0, 50.3, 34.0,
24.9, 22.5, 21.5, 13.3, 12.8, 4.0; 125Te NMR (CDCl3, 157 MHz) d
145.2; HRMS-ESI m/z calculated for C14H23NO2STe + Na+
422.0409, found 422.0392.
4.5. (S)-N-(1-(Butyltellanyl)-3-phenylpropan-2-yl)-4-
methylbenzenesulfonamide (2d)
The b-telluroamine 2d was prepared according to the procedure
described to b-telluroamine 2a, however aziridine 1b was used in-
4.9. N-(2-(Butyltellanyl)ethyl)-4-methylbenzenesulfonamide (2h)
stead of aziridine 1a. Yield: 79%; yellow oil; ½a D24
ꢁ
¼ ꢀ24:1 (c = 1.0,
The b-telluroamine 2h was prepared according to the procedure
described to b-telluroamine 2a, however aziridine 1f was used in-
stead of aziridine 1a. Yield: 83%; yellow oil; IR (film) 3277, 2957,
EtOH); IR (film) 3268, 2958, 2926, 1598, 1453, 1328, 1156 cmꢀ1
;
1H NMR (CDCl3, 500 MHz) d 7.58–7.56 (m, 2H), 7.21–7.16 (m,
5H), 7.01–6.98 (m, 2H), 4.80 (br s, 1H), 3.49–3.47 (m, 1H), 2.81
(dd, J = 12.5 Hz, J = 4.0 Hz, 1H), 2.74 (t, J = 7.0 Hz, 2H), 2.69 (dd,
J = 12.5 Hz, J = 6.0 Hz, 1H), 2.55 (t, J = 7.5 Hz, 2H), 2.40 (s, 3H),
1.67–1.61 (m, 2H), 1.33 (sex, J = 7.5 Hz, 2H), 0.89 (t, J = 7.0 Hz,
3H); 13C NMR (CDCl3, 75 MHz) d 143.1, 137.3, 136.8, 129.5,
128.5, 127.0, 126.6, 55.4, 42.1, 34.0, 24.9, 21.4, 13.3, 11.0, 4.3;
125Te NMR (CDCl3, 157 MHz) d 129.1; HRMS-ESI m/z calculated
for C20H27NO2STe + Na+ 498.0722, found 498.0714.
2926, 2867, 1597, 1455, 1325, 1156 cmꢀ1
;
1H NMR (CDCl3,
300 MHz)
d
7.80–7.73 (m, 2H), 7.31–7.24 (m, 2H), 3.20 (t,
J = 7.2 Hz, 2H), 2.63 (t, J = 7.2 Hz, 2H), 2.54 (t, J = 7.2 Hz, 2H), 2.42
(s, 3H), 1.83 (qui, J = 7.2 Hz, 2H), 1.32 (sex, J = 7.2 Hz, 2H), 0.88 (t,
J = 7.2 Hz, 3H); 13C NMR (CDCl3, 75 MHz) d 143.5, 137.1, 129.8,
127.1, 44.8, 34.2, 25.0, 21.5, 13.4, 3.3, 2.3; 125Te NMR (CDCl3,
157 MHz) d 192.2; HRMS-ESI m/z calculated for C13H21NO2STe + -
Na+ 408.0253, found 408.0250.
4.6. (S)-N-(1-(Butyltellanyl)-3-methylbutan-2-yl)-4-
4.10. (S)-tert-Butyl 1-(butylselanyl)-3-phenylpropan-2-ylcarbamate
methylbenzenesulfonamide (2e)
(2i)
The b-telluroamine 2e was prepared according to the procedure
described to b-telluroamine 2a, however aziridine 1c was used in-
The b-selenoamine 2i was prepared according to the procedure
described to b-telluroamine 2a, however elemental selenium was
used instead of elemental tellurium. Yield: 78%; white solid;
stead of aziridine 1a. Yield: 81%; yellow oil; ½a D24
¼ þ12:7 (c = 1.0,
ꢁ
CH2Cl2); IR (film) 3275, 2959, 2928, 2872, 1325, 1157, 1092 cmꢀ1
;
m.p.: 63.6–65.6 °C; ½a D24
ꢁ
¼ þ9:4 (c = 1.0, CH2Cl2); IR (KBr) 3362,
1H NMR (CDCl3, 500 MHz) d 7.79–7.77 (m, 2H), 7.30–7.28 (m, 2H),
5.03–5.01 (d, J = 8.0 Hz, 1H), 3.08–3.06 (m, 1H), 2.81 (dd, J = 12.5,
J = 4.5 Hz, 1H), 2.55 (dd, J = 12.5, J = 7.0 Hz, 1H), 2.47 (t, J = 7.0 Hz,
2H), 2.41 (s, 3H), 1.80–1.74 (m, 1H), 1.63–1.56 (m, 2H), 1.31 (sex,
J = 7.5 Hz, 2H), 0.89 (t, J = 7.5 Hz, 3H), 0.79 (d, J = 7.0 Hz, 6H); 13C
NMR (CDCl3, 125 MHz) d 143.2, 138.1, 129.6, 127.1, 59.5, 34.1,
2963, 2927, 1686, 1526, 1513, 1166, 703 cmꢀ1 1H NMR (CDCl3,
;
500 MHz) d 7.30–7.25 (m, 2H), 7.23–7.19 (m, 3H), 4.73 (br s, 1H),
4.04 (br s, 1H), 2.88–2.80 (m, 2H), 2.70–2.65 (m, 2H), 2.59 (t,
J = 7.0 Hz, 2H), 1.61 (qui, J = 7.0 Hz, 2H), 1.41 (s, 9H), 1.38 (sex,
J = 7.0 Hz, 2H), 0.90 (t, J = 7.0 Hz, 3H); 13C NMR (CDCl3, 75 MHz) d
155.1, 137.7, 129.4, 128.4, 126.5, 79.3, 51.4, 40.3, 32.6, 28.8, 28.3,

126
F. Vargas, J.V. Comasseto / Journal of Organometallic Chemistry 694 (2009) 122–126
24.9, 22.9, 13.5; 77Se NMR (CDCl3, 95 MHz) d 104.1; HRMS-ESI m/z
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calculated for C18H29NO2Se + Na+ 394.1261, found 394.1256.
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4.11. (S)-tert-Butyl 1-(butylthio)-3-phenylpropan-2-ylcarbamate (2j)
The b-thioamine 2j was prepared according to the procedure
described to b-selenoamine 2i, however elemental sulfur was used
instead of elemental tellurium. Yield: 72%; white solid; m.p.: 57.3–
59.3 °C; ½a 2D4
ꢁ
¼ þ7:1 (c = 1.0, CH2Cl2); IR (KBr) 3360, 2959, 2930,
1686, 1528, 1515, 1167, 703 cmꢀ1
;
1H NMR (CDCl3, 500 MHz) d
7.30–7.27 (m, 2H), 7.23–7.20 (m, 3H), 4.69 (br s, 1H), 3.99 (br s,
1H), 2.87–2.83 (m, 2H), 2.61–2.58 (m, 2H), 2.52 (t, J = 7.0 Hz, 2H),
1.53 (qui, J = 7.0 Hz, 2H), 1.45–1.35 (m, 11H), 0.90 (t, J = 7.0 Hz,
3H); 13C NMR (CDCl3, 75 MHz) d 155.2, 137.7, 129.4, 128.4,
126.4, 79.3, 51.1, 39.5, 36.0, 32.6, 31.8, 28.3, 21.9, 13.6; HRMS-
ESI m/z calculated for C18H29NO2S + Na+ 346.1817, found 346.1813.
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Acknowledgments
The authors gratefully acknowledge FAPESP and CNPq for finan-
cial support.
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