N-carbonylation of lithium azaenolates of amides, formamides, ureas, and carbamates with carbon monoxide mediated by selenium

Article abstract of DOI:10.1021/jo0615908

N-Carbonylation of less nucleophilic nitrogen compounds was achieved by the reaction of the lithium azaenolates with carbon monoxide and selenium. This reaction proceeds in the cases of amides, formamides, ureas, and carbamates, leading to the formation of the corresponding carbamosele-noates in good to high yields after trapping with BuI.

Full text of DOI:10.1021/jo0615908

with carbon monoxide (Scheme 1);5 however, these processes
cannot be applied to carbonylation of less nucleophilic nitrogen
compounds.
-8
N-Carbonylation of Lithium Azaenolates of
Amides, Formamides, Ureas, and Carbamates
with Carbon Monoxide Mediated by Selenium
Recently, we have found an effective method for carbonyl-
9
9
10
10
ation of ketones, aldehydes, amides, and esters by the
reaction of the corresponding lithium enolates 1 with carbon
monoxide and selenium (eq 1).
,
†
‡
‡
Shin-ichi Fujiwara,* Kazuhiro Okada, Yasukazu Shikano,
‡
†
‡
Yoshihiko Shimizu, Tsutomu Shin-ike, Jun Terao,
,
‡
‡,§
Nobuaki Kambe,* and Noboru Sonoda
Department of Chemistry, Osaka Dental UniVersity, Hirakata,
Osaka 573-1121, Japan, and Department of Applied Chemistry,
Graduate School of Engineering, Osaka UniVersity, Suita,
Osaka 565-0871, Japan
fujiwara@cc.osaka-dent.ac.jp;
kambe@chem.eng.osaka-u.ac.jp
In addition, we have already succeeded in carbonylation of
hydrocarbons, which have pKa values ranging from 18 to 31.5.
11
These successful results prompted us to examine N-carbonyl-
ation of lithium azaenolates of less nucleophilic nitrogen
compounds for the following reasons: (1) lithium azaenolates
ReceiVed August 1, 2006
2
of amides, formamides, ureas, and carbamates have structures
similar to those of lithium enolates 1 of ketones, aldehydes,
amides, and esters, respectively; and (2) pKa values of these
nitrogen compounds may be in the range from 18 to 31.5.1
Here we describe the first examples of N-carbonylation of
lithium azaenolates with carbon monoxide mediated by selenium
2,13
(eq 2).
N-Carbonylation of less nucleophilic nitrogen compounds
was achieved by the reaction of the lithium azaenolates with
carbon monoxide and selenium. This reaction proceeds in
the cases of amides, formamides, ureas, and carbamates,
leading to the formation of the corresponding carbamosele-
noates in good to high yields after trapping with BuI.
We first examined N-carbonylation of lithium azaenolates of
amides. When a lithium azaenolate of N-methylacetamide 3a,
generated by deprotonation of 3a with LDA in the presence of
HMPA, was allowed to react with selenium at -78 °C and then
with CO (1 atm) at 20 °C, a stoichiometric amount of CO was
absorbed within 1 h. Addition of BuI and usual workup followed
by purification by column chromatography on silica gel using
Et2O gave 62% yield of carbamoselenoate 4a in pure
The use of carbon monoxide for the N-carbonylation of
nitrogen nucleophiles is an important transformation in organic
synthesis.1 However, N-carbonylation of less nucleophilic
nitrogen compounds such as amides, ureas, and carbamates
is not an easy process. We already disclosed that selenium
exhibited extremely high activity in the carbonylation of amines
2
3
4
†
Osaka Dental University.
Osaka University.
Emeritus Professor of Osaka University.
1) (a) Falbe, J. New Syntheses with Carbon Monoxide; Springer-
(5) (a) Sonoda, N.; Yasuhara, T.; Kondo, K.; Ikeda, T.; Tsutsumi, S. J.
Am. Chem. Soc. 1971, 93, 6344. (b) Sonoda, N. Pure Appl. Chem. 1993,
65, 699 and references cited therein.
(6) (a) Kondo, K.; Takarada, M.; Murai, S.; Sonoda, N. Synthesis 1979,
597. (b) Yoshida, T.; Kambe, N.; Murai, S.; Sonoda, N. J. Org. Chem.
1987, 52, 1611.
(7) Fujiwara, S.; Shikano, Y.; Shin-ike, T.; Kambe, N.; Sonoda, N. J.
Org. Chem. 2002, 67, 6275.
(8) For the related imidoylation of amines, see: Maeda, H.; Matsuya,
T.; Kambe, N.; Sonoda, N.; Fujiwara, S.; Shin-ike, T. Tetrahedron 1997,
53, 12159.
‡
§
(
Verlag: New York, 1980. (b) Colquhoun, H. M.; Thompson, D. G.; Twigg,
M. V. Carbonylation: Direct Synthesis of Carbonyl Compounds; Plenum
Press: New York, 1991. (c) Otera, J., Ed. Modern Carbonyl Chemistry;
Wiley-VCH: Weinheim, Germany, 2000. (d) Metallinos, C. In Science of
Synthesis: Compounds of Group 1 (Li‚‚‚Cs); Trost, B. M., Ed.; Georg
Thieme Verlag: Stuttgart, 2005; Vol. 8a, pp 798-803.
(
2) (a) Falbe, J.; Korte, F. Angew. Chem., Int. Ed. Engl. 1962, 1, 266.
b) Falbe, J.; Korte, F. Chem. Ber. 1962, 95, 2680. (c) Yamamoto, T.;
Igarashi, K.; Ishizu, J.; Yamamoto, A. J. Chem. Soc., Chem. Commun. 1979,
54. (d) Larock, R. C.; Fellows, C. A. J. Am. Chem. Soc. 1982, 104, 1900.
e) Roberto, D.; Alper, H. Organometallics 1984, 3, 1767. (f) Yoshida, T.;
Kambe, N.; Murai, S.; Sonoda, N. Bull. Chem. Soc. Jpn. 1987, 60, 1793.
g) Miyata, T.; Mizuno, T.; Nagahama, Y.; Nishiguchi, I.; Hirashima, T.;
(
(9) Fujiwara, S.; Nishiyama, A.; Shin-ike, T.; Kambe, N.; Sonoda, N.
Org. Lett. 2004, 6, 453.
5
(
(10) Kambe, N.; Nishiyama, A.; Fujiwara, S.; Shin-ike, T.; Sonoda, N.
Phosphorus, Sulfur Silicon Relat. Elem. 2005, 1001.
(11) (a) Maeda, H.; Fujiwara, S.; Shin-ike, T.; Kambe, N.; Sonoda, N.
J. Am. Chem. Soc. 1996, 118, 8160. (b) Maeda, H.; Fujiwara, S.; Nishiyama,
A.; Shin-ike, T.; Kambe, N.; Sonoda, N. Synthesis 1997, 342.
(12) For example, pK values of acetamide (CH C(O)NH ), formamide
(
Sonoda, N. Heteroatom Chem. 1991, 2, 473. (h) Piotti, M. E.; Alper, H. J.
Am. Chem. Soc. 1996, 118, 111.
(
alkenylureas leading to protected â-aminoacids, see: (a) Tamaru, Y.; Hojo,
M.; Higashimura, H.; Yoshida, Z. J. Am. Chem. Soc. 1988, 110, 3994. (b)
Tamaru, Y.; Kimura, M. Synlett 1997, 749.
a
3
2
3) For intramolecular palladium-catalyzed aminocarbonylation of N-
2 2 2 2
(HC(O)NH ), urea (H NC(O)NH ), and O-ethylcarbamate (EtOC(O)NH )
in DMSO are 25.5 (ref 13a), 23.5 (ref 13a), 26.9 (ref 13b), and 24.2 (ref
13c), respectively.
(13) (a) Bordwell, F. G.; Bartmess, J. E.; Hautala, J. A. J. Org. Chem.
1978, 43, 3095. (b) Bordwell, F. G.; Ji, G.-Z. J. Am. Chem. Soc. 1991,
113, 8398. (c) Bordwell, F. G.; Fried, H. E. J. Org. Chem. 1991, 56, 4218.
(
4) (a) Larksarp, C.; Alper, H. J. Org. Chem. 1999, 64, 9194. (b)
Kadnikov, D. V.; Larock, R. C. J. Org. Chem. 2004, 69, 6772.
1
0.1021/jo0615908 CCC: $37.00 © 2007 American Chemical Society
Published on Web 12/09/2006
J. Org. Chem. 2007, 72, 273-276
273

TABLE 2. N-Carbonylation of Ureasa
SCHEME 1. Selenium-Assisted Carbonylation of Amines
TABLE 1. N-Carbonylation of Amides and Formamidesa
a
Conditions: 7 (2.0 mmol), LDA (2.3 mmol), Se (2.1 mmol), THF (25
mL), -78 °C, 30 min; CO (1 atm), 0 °C, time; Bul (4.0 mmol), 0 °C to rt,
3
0 min. b In the presence of HMPA (6 mmol).
SCHEME 2. Plausible Reaction Pathways
N-Carbonylation of ureas was then examined and was found
to proceed well under similar conditions without HMPA.
Representative results are shown in Table 2. Ureas 7a-d having
a butyl, methyl, allyl, or cyclohexyl group on the nitrogen atom
afforded expected products 8a-d in high yields. When R was
a tertiary alkyl or an aryl group, the yields of carbonylation
products dropped probably due to the same reasons described
above. However, addition of 3 equiv of HMPA improved the
yields (runs 5 and 6).
Since ureas employed in this study were prepared by the
reaction of piperidine with the corresponding isocyanates, we
then examined one-pot carbonylation starting from piperidine
and butyl isocyanate, and the expected product 8a was obtained
in 54% yield (eq 3).
a
Conditions: 3 or 5 (2.0 mmol), Se (2.0 mmol), LDA (2.2 mmol),
HMPA (6.0 mmol), THF (25 mL), -78 °C, 30 min, then 20 °C, 30 min;
b
CO (1 atm), 20 °C, 1 h; Bul (4.0 mmol), 20 °C, 30 min. Yields in
parentheses are NMR yields. At 0 °C. At -23 °C. At -78 °C. f At
c
d
e
1
3.5 mmol scale.
form (run 1 in Table 1). In the absence of HMPA, 4a was not
obtained. Carbonylation at 0 and -23 °C also afforded the
product in high yields; however, carbonylation at -78 °C did
not proceed (runs 2-4). N-Methylpropionamide (3b), N-
methylbenzamide (3c), and pyrrolidone (3d) afforded the
carbonylated products (runs 5-7). However, acetamide, an
unprotected amide, gave the desired product 4e only in 5% yield
due probably to decomposition of the intermediary lithium
carbamoselenoate. The effect of the substituent at the nitrogen
atom was then examined by the use of a variety of formamides,
and the results are also summarized in Table 1. Formamides
having a primary or secondary alkyl group, 5a-e, gave the
products in good to high yields (runs 8-12). However,
introduction of a tertiary alkyl group on the nitrogen reduced
the rate of CO absorption (run 13). Carbonylation did not
proceed when phenyl-substituted formamide was used, due
probably to its low nucleophilicity.
Interestingly, carbonylation of imidazolidine (7g) gave di-
carbonylated product 8g in 40% yield under similar conditions
without the monocarbonylated product. Thus, by the use of 2
2
74 J. Org. Chem., Vol. 72, No. 1, 2007

equiv of Se and LDA, the yield of 8g was improved up to 68%
eq 4).
dropwise N-methylacetamide (2a, 2.0 mmol) in THF (5 mL) over
10 min, and stirring was continued for an additional 20 min. The
mixture temperature was then increased to 20 °C, and argon was
replaced with carbon monoxide. A clear black solution was obtained
within 1 h, and BuI (4.0 mmol) was added and stirring was
(
continued for an additional 30 min. Aqueous saturated NH
solution (100 mL) was added, and the product was extracted with
Et O (50 mL). After the organic layer was dried over MgSO
evaporation of the solvent gave a brown residue. Purification by
column chromatography on silica gel using Et O yielded 62% of
a as a brown oil: 1H NMR (270 MHz, CDCl
) δ 0.93 (t, J ) 7.3
Hz, 3 H), 1.42 (sext, J ) 7.3 Hz, 2 H), 1.69 (quint, J ) 7.3 Hz, 2
4
Cl
2
4
,
2
4
3
N-Carbonylation of carbamates also proceeded efficiently
13
H), 2.40 (s, 3 H), 2.86 (t, J ) 7.3 Hz, 2 H), 3.29 (s, 3 H);
NMR (68 MHz, CDCl ) δ 13.6, 23.2, 25.8, 26.8, 31.8, 32.2, 169.6,
72.2. Anal. Calcd for C Se: C, 40.68; H, 6.41; N, 5.93.
Found: C, 40.86; H, 6.54; N, 5.82.
Se-Butyl Methylpropionylcarbamoselenoate (4b): H NMR
270 MHz, CDCl
C
without HMPA. As shown in eq 5, N-ethyl O-ethylurethane (9a),
N-butyl O-tert-butylurethane (9b), and oxazolidine-2-one (9c)
were carbonylated to give the expected products 10a-c in high
yields.
3
1
8 2
H15NO
1
(
3
) δ 0.93 (t, J ) 7.3 Hz, 3 H), 1.18 (t, J ) 7.3
Hz, 3 H), 1.42 (sext, J ) 7.3 Hz, 2 H), 1.68 (quint, J ) 7.3 Hz, 2
H), 2.66 (q, J ) 7.3 Hz, 2 H), 2.84 (t, J ) 7.3 Hz, 2 H), 3.29 (s,
3
3
H); 13C NMR (68 MHz, CDCl
3
) δ 8.53, 13.6, 23.2, 26.6, 30.7,
Se: C, 43.20;
9 2
1.8, 31.9, 169.5, 175.9. Anal. Calcd for C H17NO
H, 6.86; N, 5.60. Found: C, 43.13; H, 6.93; N, 5.59.
Se-Butyl Benzoylmethylcarbamoselenoate (4c): mp 62.5-64.0
1
°
(
C; H NMR (270 MHz, CDCl
3
) δ 0.93 (t, J ) 7.3 Hz, 3 H), 1.43
sext, J ) 7.3 Hz, 2 H), 1.70 (quint, J ) 7.3 Hz, 2 H), 2.88 (t,
13
J ) 7.3 Hz, 2 H), 3.29 (s, 3 H), 7.43-7.56 (m, 5 H); C NMR (68
MHz, CDCl ) δ 13.6, 23.2, 26.4, 31.9, 35.7, 127.8, 128.6, 131.7,
34.7, 169.7, 173.1. Anal. Calcd for C13 Se: C, 52.34; H,
.76; N, 4.70. Found: C, 52.29; H, 5.84; N, 4.56.
Se-Butyl 2-Oxopyrrolidine-1-carboselenoate (4d): H NMR
270 MHz, CDCl
3
N-Carbonylation of lithium azaenolates may proceed through
1
5
H17NO
2
a similar mechanism we already proposed for carbonylation of
9
lithium enolates. Plausible pathways exemplified by carbonyl-
1
ation of azaenolate of formamide are depicted in Scheme 2.
Reaction of azaenolate with selenium affords selenolate 11,
which then reacts with carbon monoxide to give lithium
selenocarbonate 13, probably via formal rearrangement of 12.
HMPA may enhance the nucleophilicity of azaenolate to react
with selenium and/or that of selenolate 11 to react with carbon
monoxide. Unlike the case of lithium enolates of aldehydes,
alkylation products of 13 were not obtained at all even when
carbonylation and trapping were performed at lower tempera-
tures. This result indicates that [1,3]-rearrangement of 13 to
lithium carbamoselenoate 14 proceeds very fast or that the
nitrogen atom of lithium azaenolate attacks the central carbon
of carbonyl selenide to produce 14 directly. Finally, product 6
is obtained by trapping 14 with BuI. As for the formation of
carbamoselenoate 14 from 12, a path involving lithoxycarbene
(
3
) δ 0.92 (t, J ) 7.3 Hz, 3 H), 1.42 (sext, J ) 7.3
Hz, 2 H), 1.68 (quint, J ) 7.3 Hz, 2 H), 2.10 (quint, J ) 7.3 Hz,
2 H), 2.61 (t, J ) 7.3 Hz, 2 H), 2.87 (t, J ) 7.3 Hz, 2 H), 3.89 (t,
J ) 7.3 Hz, 2 H); 13C NMR (68 MHz, CDCl
) δ 13.6, 17.6, 23.2,
Se:
3
9 2
24.5, 32.0, 33.0, 46.4, 166.4, 175.6. Anal. Calcd for C H15NO
C, 43.55; H, 6.10; N, 5.64. Found: C, 43.52; H, 6.22; N, 5.55.
Se-Butyl Acetylcarbamoselenoate (4e): mp 106.0-108.0 °C;
1
H NMR (270 MHz, CDCl ) δ 0.93 (t, J ) 7.3 Hz, 3 H), 1.42
3
(
sext, J ) 7.3 Hz, 2 H), 1.70 (quint, J ) 7.3 Hz, 2 H), 2.24 (s, 3
13
H), 2.68 (t, J ) 7.3 Hz, 2 H), 9.64 (s, 1 H); C NMR (68 MHz,
CDCl
for C
.04; N, 6.38.
3
) δ 13.6, 23.1, 24.2, 25.4, 32.0, 169.5, 170.4. Anal. Calcd
9
H
13NO
2
Se: C, 37.85; H, 5.90; N, 6.31. Found: C, 37.84; H,
6
1
Se-Butyl Formylmethylcarbamoselenoate (6a): H NMR (270
MHz, CDCl
2 H), 1.74 (quint, J ) 7.3 Hz, 2 H), 3.06 (t, J ) 7.3 Hz, 2 H), 3.18
(s, 3 H), 9.20 (s, 1 H); 13C NMR (68 MHz, CDCl
) δ 13.5, 23.0,
27.4, 28.3, 32.2, 161.4, 170.1. Anal. Calcd for C Se: C,
3
) δ 0.95 (t, J ) 7.3 Hz, 3 H), 1.44 (sext, J ) 7.3 Hz,
1
5 as an intermediate may also be possible.
3
In conclusion, N-carbonylation of less nucleophilic nitrogen
7 2
H13NO
3
7.84; H, 5.91; N, 6.31. Found: C, 37.98; H, 6.05; N, 6.46.
Se-Butyl Butylformylcarbamoselenoate (6b): H NMR (270
compounds such as amides, formamides, ureas, and carbamates
was attained by the reaction of the corresponding lithium
azaenolates with selenium and carbon monoxide.
1
MHz, CDCl
H), 1.34 (sext, J ) 7.3 Hz, 2 H), 1.43 (sext, J ) 7.3 Hz, 2 H), 1.59
quint, J ) 7.3 Hz, 2 H), 1.73 (quint, J ) 7.3 Hz, 2 H), 3.06 (t,
3
) δ 0.94 (t, J ) 7.3 Hz, 3 H), 0.95 (t, J ) 7.3 Hz, 3
(
Experimental Section
13
J ) 7.3 Hz, 2 H), 3.68 (t, J ) 7.3 Hz, 2 H), 9.15 (s, 1 H);
NMR (68 MHz, CDCl ) δ 13.5, 13.7, 20.1, 23.0, 27.2, 30.6, 32.2,
2.5, 161.7, 169.3. Anal. Calcd for C10 Se: C, 45.45; H,
.26; N, 5.30. Found: C, 45.31; H, 7.46; N, 5.42.
C
THF was distilled from sodium benzophenone ketyl. Diisopro-
3
4
7
H19NO
2
pylamine and BuI were distilled from CaH
used as purchased. HMPA was fractionally distilled and dried over
CaH
2
. BuLi and Se were
1
. Formamides 5a-f were prepared from the corresponding
Se-Butyl Allylformylcarbamoselenoate (6c): H NMR (270
MHz, CDCl ) δ 0.94 (t, J ) 7.3 Hz, 3 H), 1.43 (sext, J ) 7.3 Hz,
2
amines and ethyl formate. Ureas 7a-f were prepared from the
3
corresponding isocyanates and piperidine.
2 H), 1.73 (quint, J ) 7.3 Hz, 2 H), 3.07 (t, J ) 7.3 Hz, 2 H), 4.32
(d, J ) 5.6 Hz, 2 H), 5.21 (dd, J ) 10.3, 2.7 Hz, 1 H), 5.23 (dd,
J ) 17.1, 2.7 Hz, 1 H), 5.80 (ddt, J ) 17.1, 10.3, 5.6 Hz, 1 H),
Se-Butyl Acetylmethylcarbamoselenoate (4a): Typical Pro-
cedure for Carbonylation of Amides and Formamides. To a THF
9.19 (s, 1 H); 13C NMR (68 MHz, CDCl
) δ 13.5, 23.0, 27.3, 32.3,
44.5, 118.2, 131.3, 161.3, 169.2. Anal. Calcd for C Se: C,
43.55; H, 6.10; N, 5.64. Found: C, 43.67; H, 6.23; N, 5.79.
Se-Butyl Formyl-trans-3-pentenylcarbamoselenoate (6d): H
NMR (270 MHz, CDCl ) δ 0.94 (t, J ) 7.3 Hz, 3 H), 1.43 (sext,
(20 mL) solution of LDA, prepared from BuLi (1.60 M in hexane,
3
1
.4 mL, 2.2 mmol) and diisopropylamine (2.2 mmol) at -78 °C,
9 2
H15NO
were added elemental selenium (2.0 mmol) and HMPA (6 mmol)
1
at -78 °C under argon. A black suspension was obtained within
3
0 min at the same temperature. To the suspension was added
3
J. Org. Chem, Vol. 72, No. 1, 2007 275

J ) 7.3 Hz, 2 H), 1.64 (d, J ) 6.2 Hz, 3 H), 1.73 (quint, J ) 7.3
Hz, 2 H), 2.27 (dt, J ) 7.3, 6.8 Hz, 2 H), 3.36 (t, J ) 7.3 Hz, 2 H),
1.12-1.92 (m, 22 H), 2.93 (t, J ) 7.3 Hz, 2 H), 3.33 (br s, 2 H),
3.65 (br s, 0.5 H), 3.87 (br s, 0.5 H); 13C NMR (100 MHz, CDCl
)
3
1
3.70 (t, J ) 7.3 Hz, 2 H), 5.33 (dt, J ) 15.3, 6.8 Hz, 1 H), 5.48
δ 13.5, 22.9, 24.1, 25.1, 25.5, 25.9, 26.5 ( JSe-C ) 59.0 Hz), 30.8,
32.7, 46.2, 57.7, 152.9, 163.0. Anal. Calcd for C H N O Se: C,
(
dq, J ) 15.3, 6.2 Hz, 1 H), 9.13 (s, 1 H); 13C NMR (68 MHz,
CDCl
17
30
2
2
3
) δ 13.5, 17.9, 23.0, 27.2, 31.6, 32.3, 42.4, 126.5, 128.4,
54.68; H, 8.10; N, 7.50. Found: C, 55.06; H, 7.96; N, 7.62.
Se-Butyl tert-Butyl(piperidine-1-carbonyl)selenocarbamate
1
61.6, 169.1. Anal. Calcd for C11
H19NO
2
Se: C, 47.82; H, 6.95; N,
5
.07. Found: C, 47.83; H, 7.01; N, 4.91.
Se-Butyl Cyclohexylformylcarbamoselenoate (6e): H NMR
1
(
8e): H NMR (400 MHz, CDCl
3
) δ 0.91 (t, J ) 7.3 Hz, 3 H),
1
1
.34-1.83 (m, 19 H), 2.88 (t, J ) 7.4 Hz, 2 H), 3.49 (br s, 4 H);
(
270 MHz, CDCl
3
) δ 0.94 (t, J ) 7.3 Hz, 3 H), 1.15-2.11 (m, 14
13
C NMR (100 MHz, CDCl
t, J ) 59.5 Hz), 28.0, 32.6, 44.4, 48.1, 59.7, 153.5, 161.7 ( JSe-C
59.5 Hz). Anal. Calcd for C15 Se: C, 51.87; H, 8.12; N,
.06. Found: C, 51.80; H, 8.08; N, 8.04.
Se-Butyl Phenyl(piperidine-1-carbonyl)selenocarbamate (8f):
3
) δ 13.5, 23.1, 24.0, 24.9, 25.5, 26.8
H), 3.00 (t, J ) 7.3 Hz, 2 H), 4.13-4.22 (m, 1 H), 9.04 (s, 1 H);
1
(
)
8
13
C NMR (68 MHz, CDCl
2.1, 56.4, 162.8, 168.5. Anal. Calcd for C12H21NO
3
) δ 13.6, 23.1, 25.1, 26.3, 27.2, 30.1,
Se: C, 49.65;
28 2 2
H N O
3
2
H, 7.31; N, 4.83. Found: C, 49.37; H, 7.22; N, 4.72.
Se-Butyl tert-Butylformylcarbamoselenoate (6f): 1H NMR
1
H NMR (400 MHz, CDCl
3
) δ 0.89 (t, J ) 7.4 Hz, 3 H), 1.36
(
3
270 MHz, CDCl ) δ 0.93 (t, J ) 7.3 Hz, 3 H), 1.42 (sext, J ) 7.3
(
2
sext, J ) 7.4 Hz, 2 H), 1.59-1.70 (m, 8 H), 2.88 (t, J ) 7.3 Hz,
Hz, 2 H), 1.57 (s, 9 H), 1.68 (quint, J ) 7.3 Hz, 2 H), 2.86 (t, J )
7
2
NO
5
13
H), 3.56 (br s, 4 H), 7.39-7.46 (m, 5 H); C NMR (100 MHz,
1
.3 Hz, 2 H), 8.98 (s, 1 H); 13C NMR (68 MHz, CDCl
3.2, 26.6, 29.5, 31.7, 61.0, 163.7, 169.4. Anal. Calcd for C10
Se: C, 45.45; H, 7.26; N, 5.30. Found: C, 45.51; H, 7.35; N,
.45.
Se-Butyl
8a): Typical Procedure for Carbonylation of Ureas and
3
) δ 13.6,
CDCl
6.6, 128.8, 128.9, 128.9, 136.7, 152.7, 165.7. Anal. Calcd for
Se: C, 55.58; H, 6.58; N, 7.63. Found: C, 55.82; H,
3
) δ 13.5, 23.0, 24.2, 25.6, 27.4 ( JSe-C ) 59.0 Hz), 32.4,
19
H -
4
2
17 24 2 2
C H N O
6.60; N, 7.63.
Butyl(piperidine-1-carbonyl)selenocarbamate
Di-Se-butyl 2-Oxoimidazolidine-1,3-dicarboselenoate (8g):
Two equivalents of Se and LDA and 4 equiv of BuI were used;
(
Carbamates. To a THF (20 mL) solution of LDA, prepared from
BuLi (1.60 M in hexane, 1.4 mL, 2.2 mmol) and diisopropylamine
1
mp 102.0-104.0 °C; H NMR (270 MHz, CDCl
3
) δ 0.93 (t, J )
.3 Hz, 6 H), 1.42 (sext, J ) 7.3 Hz, 4 H), 1.70 (quint, J ) 7.3 Hz,
H), 2.72 (t, J ) 7.3 Hz, 4 H), 4.00 (s, 4 H); 13C NMR (68 MHz,
) δ 13.6, 23.1, 25.2, 31.9, 40.4, 152.3, 166.1; HRMS (EI)
calcd for C13 Se 413.9977, found 413.9969.
7
4
(
2.2 mmol) at -78 °C, was added elemental selenium (2.0 mmol)
at -78 °C under argon. A black suspension was obtained within
0 min at the same temperature. To the suspension was added
CDCl
3
3
H N
22 2
O
3
2
dropwise N-butylpiperidylformamide (7a, 2.0 mmol) in THF (5 mL)
over 10 min, and stirring was continued for an additional 20 min.
The mixture was then warmed to 0 °C, and argon was replaced
with carbon monoxide. A clear pale brown solution was obtained
within 1.5 h, and BuI (4.0 mmol) was added and stirring was
1
Ethoxy-N-ethyl-N-(butylselenocarbonyl)formamide (10a): H
NMR (400 MHz, CDCl ) δ 0.93 (t, J ) 7.3 Hz, 3 H), 1.17 (t, J )
3
7.0 Hz, 3 H), 1.31-1.47 (m, 5 H), 1.68 (quint, J ) 7.5 Hz, 2 H),
2.81 (t, J ) 7.4 Hz, 2 H), 3.83 (q, J ) 6.9 Hz, 2 H), 4.31 (q, J )
1
3
continued for an additional 30 min. Aqueous saturated NH
solution (100 mL) was added, and the product was extracted with
Et
O (2 × 50 mL). After the combined organic layer was dried
over MgSO , evaporation of the solvent gave a brown residue.
Purification by column chromatography on silica gel using n-hex-
4
Cl
7.0 Hz, 2 H); C NMR (100 MHz, CDCl ) δ 13.6, 13.8, 14.3,
3
1
23.2, 26.1 ( J -C ) 60.9 Hz), 31.8, 40.5, 62.9, 154.3, 167.8
Se
1
2
( J -C ) 166.4 Hz). Anal. Calcd for C H NO Se: C, 42.86; H,
Se
10 19
3
4
6.83; N, 5.00. Found: C, 43.14; H, 6.81; N, 5.13.
tert-Butoxy-N-butyl-N-(butylselenocarbonyl)formamide (10b):
1
ane/Et
MHz, CDCl
.70 (m, 10 H), 2.92 (t, J ) 7.2 Hz, 2 H), 3.45 (br s, 4 H), 3.57 (br
2
O (4:1) yielded 86% of 8a as a brown oil: H NMR (400
1
H NMR (400 MHz, CDCl
3
) δ 0.92 (t, J ) 7.2 Hz, 6 H), 1.29-
3
) δ 0.90-0.94 (m, 6 H), 1.32-1.43 (m, 4 H), 1.56-
1
.68 (m, 17 H), 2.79 (t, J ) 7.6 Hz, 2 H), 3.72 (t, J ) 7.4 Hz, 2
1
13
H); C NMR (100 MHz, CDCl
3
) δ 13.6, 13.8, 20.0, 23.3, 26.0
13
s, 2 H); C NMR (100 MHz, CDCl
4.2, 25.7, 26.7 ( JSe-C ) 58.5 Hz), 30.9, 32.6, 46.5, 47.0, 154.5,
64.3 ( JSe-C ) 136.5 Hz); HRMS (EI) calcd for C15
3
) δ 13.5, 13.7, 20.1, 23.0,
1
(
(
JSe-C ) 61.3 Hz), 28.1, 30.7, 31.8, 45.3, 83.5, 153.1, 167.8
1
2
1
3
1
3
JSe-C ) 163.7 Hz); HRMS (EI) calcd for C14H27NO Se 337.1156,
1
28 2 2
H N O Se
found 337.1151.
48.1316, found 348.1324.
Se-Butyl 2-Oxooxazolidine-3-carboselenoate (10c): mp 62.5-
Se-Butyl Methyl(piperidine-1-carbonyl)selenocarbamate (8b):
1
1
64.0 °C; H NMR (270 MHz, CDCl
.42 (sext, J ) 7.3 Hz, 2 H), 1.69 (quint, J ) 7.3 Hz, 2 H), 2.91
(t, J ) 7.3 Hz, 2 H), 4.09 (t, J ) 7.8 Hz, 2 H), 4.47 (t, J ) 7.8 Hz,
2 H); 13C NMR (68 MHz, CDCl
) δ 13.6, 23.1, 25.2, 32.0, 43.3,
2.8, 153.8, 162.2. Anal. Calcd for C Se: C, 38.40; H, 5.25;
N, 5.60. Found: C, 38.39; H, 5.32; N, 5.43.
3
) δ 0.93 (t, J ) 7.3 Hz, 3 H),
H NMR (400 MHz, CDCl
sext, J ) 7.4 Hz, 2 H), 1.64-1.72 (m, 8 H), 2.92 (t, J ) 7.3 Hz,
3
H), 3.12 (s, 3 H), 3.44 (br s, 4 H); C NMR (100 MHz, CDCl )
3
) δ 0.92 (t, J ) 7.3 Hz, 3 H), 1.40
1
(
2
13
1
3
δ 13.6, 23.0, 24.2, 25.7, 26.7 ( JSe-C ) 59.0 Hz), 32.6, 33.8, 46.6,
6
8 3
H13NO
1
55.2, 165.3. Anal. Calcd for C12 Se: C, 47.21; H, 7.26;
22 2 2
H N O
N, 9.18. Found: C, 47.48; H, 7.20; N, 9.19.
Se-Butyl Allyl(piperidine-1-carbonyl)selenocarbamate (8c):
1
H NMR (400 MHz, CDCl
3
) δ 0.91 (t, J ) 7.3 Hz, 3 H), 1.40
Acknowledgment. This work was supported in part by a
Grant-in-Aid from the Ministry of Education, Science, Sports
and Culture, Japan.
(
2
sext, J ) 7.1 Hz, 2 H), 1.63-1.72 (m, 8 H), 2.93 (t, J ) 7.3 Hz,
H), 3.47 (br s, 4 H), 4.20 (d, J ) 6.3 Hz, 2 H), 5.21 (d, J ) 10.3
13
Hz, 1 H), 5.29 (d, J ) 17.1 Hz, 1 H), 5.80-5.90 (m, 1 H);
C
NMR (100 MHz, CDCl
3
) δ 13.5, 13.6, 13.7, 23.0, 24.2, 25.7, 26.8
Supporting Information Available: Characterization data of
1
(
JSe-C ) 58.5 Hz), 32.6, 46.6, 49.4, 118.9, 131.96, 131.99, 154.2,
1
13
all new compounds ( H and C NMR, IR, MS, HRMS, or elemental
analysis). This material is available free of charge via the Internet
at http://pubs.acs.org.
1
64.4. Anal. Calcd for C14 Se: C, 50.75; H, 7.30; N, 8.46.
24 2 2
H N O
Found: C, 50.74; H, 7.28; N, 8.56.
Se-Butyl Cyclohexyl(piperidine-1-carbonyl)selenocarbamate
1
(
8d): H NMR (400 MHz, CDCl
3
) δ 0.91 (t, J ) 7.3 Hz, 3 H),
JO0615908
2
76 J. Org. Chem., Vol. 72, No. 1, 2007