Alkyl Transfer from Selenium(IV)
Organometallics, Vol. 28, No. 12, 2009 3433
nitrogen atmosphere and freshly distilled prior to use. Benzene was
dried over 3A molecular sieves. Chromatography was performed
with silica gel (230-400 mesh, 60 Å). Bis(ferrocenyl) diselenide,15
[[bis(1-methylethyl)amino]carbonyl]ferrocene,16,17 di-n-heptyl di-
selenide,20 di-n-hexyl diselenide,19 di-n-pentyl diselenide,18 di-n-
butyl diselenide,19 di-n-propyl diselenide,18 diisopropyl diselenide,19
1-[[bis(1-methylethyl)amino]carbonyl]-2-(butylseleno)fer-
rocene (7d),16 1-[[bis(1-methylethyl)amino]carbonyl]-2-(phenylse-
leno)ferrocene (29),16,17 and (n-hexylseleno)benzene (3)12 were
prepared by literature procedures. Concentration in vacuo was
performed on a Bu¨chi rotary evaporator. NMR spectra were
recorded on a Varian Gemini-300 or Inova 500 instrument with
residual solvent signal of CDCl3 as internal standard (δ 7.26 for
proton, δ 77.1 for carbon). Infrared spectra were recorded on a
Perkin-Elmer FT-IR instrument. Elemental analyses were conducted
by Atlantic Microlabs, Inc. The lactone products 24,22 27,23 and
2824 are known compounds, and spectral characterization is
compiled in the Supporting Information.
were washed with water, dried over Na2SO4, and concentrated in
vacuo. The crude product was purified via chromatography on SiO2
eluted with hexanes to give 412 mg (75%) of 6 as a yellow liquid:
1H NMR (500 MHz, CDCl3) δ 4.31 (t, J ) 2.0 Hz, 2H), 4.19 (t, J
) 2.0, 2H), 4.18 (s, 5H), 2.59 (t, J ) 7.5 Hz, 2H), 1.59 (m, 2H),
1.33-1.22 (m, 4H), 0.87 (t, J ) 7.5 Hz, 3H); 13C NMR (125 MHz,
CDCl3) δ 75.2, 69.6, 69.4, 31.9, 30.7, 29.9, 29.8, 28.9, 22.7, 14.2;
IR (film, NaCl) 2954, 2924, 2853, 1466, 1150, 1106, 1020, 1001,
881, 818 cm-1; HRMS (ESI) m/z 364.0387 (calcd for C17H24Fe80Se:
364.0393).
General Procedure for the Preparation of 1-[[Bis(1-methyl-
ethyl)amino]carbonyl]-2-(alkylseleno)ferrocenes 7. Preparation
of 1-[[Bis(1-methylethyl)amino]carbonyl]-2-(n-hexylseleno)fer-
rocene (7f). [[Bis(1-methylethyl)amino]carbonyl]ferrocene (1.878
g, 6.0 mmol) in ether (10 mL) was added via cannula to a solution
of TMEDA (1.55 g, 13.4 mmol) and n-BuLi (5.30 mL of a 2.5 M
solution in hexanes, 13.3 mmol) in ether (10 mL) at -78 °C under
Ar. The resulting orange-colored reaction mixture was stirred for
45 min at -78 °C. Di-n-hexyl diselenide (8.21 g, 25 mmol) was
added via syringe and stirring was continued for 15 min at -78 °C
and then 0.5 h at room temperature. During this time, the
heterogeneous reaction mixture became homogeneous. The reaction
mixture was quenched with saturated, aqueous NH4Cl solution (50
mL), and the organic products were extracted with ether (3 × 25
mL), dried over Na2SO4, and concentrated in vacuo. The crude
product was purified via chromatography on SiO2 eluted with
hexanes/ethyl acetate (95/5) to give 2.70 g (94%) of 7f as an orange
Preparation of 2-N,N-Dimethylaminobenzyl Hexyl Selenide
(4). Sodium borohydride (100 mg, 3.0 mmol) was added to bis(2-
N,N-dimethylaminobenzyl) diselenide13 (426 mg, 1.0 mmol) in
EtOH (15 mL) at 0 °C under Ar. The resulting solution was stirred
0.5 h at 0 °C. 1-Bromohexane (0.28 mL, 2 mmol) was added via
syringe and the resulting mixture was stirred for an additional 1 h.
The reaction mixture was poured into saturated NaHCO3 (50 mL),
and the organic products were extracted with ether (4 × 10 mL).
The combined organic extracts were washed with water, dried over
Na2SO4, and concentrated in vacuo. Selenide 4 was obtained as a
1
oil: H NMR (500 MHz, CDCl3) δ 4.37 (m, 1H), 4.31 (s, 5H),
1
4.28 (m, 1H), 4.18 (t, J ) 3 Hz, 1H), 3.59 (br s, 1H), 3.48 (br s,
1H), 2.70 (t, J ) 7.5 Hz, 2H), 1.68-1.62 (m, 2H), 1.51 (br s, 1H),
1.43-1.24 (m, 8H), 1.09 (br s, 6H), 0.88 (t, J ) 7.5 Hz, 3H); 13C
NMR (125 MHz, CDCl3) δ 167.0, 89.8, 74.9, 72.8, 71.1, 67.3, 67.1,
65.7, 50.2 (br), 45.8 (br), 31.2, 30.4, 30.3, 29.4, 28.5, 22.4, 20.9,
15.2, 13.9; IR (film, NaCl) 1637 cm-1; HRMS (ESI) m/z 477.1222
(calcd for C23H35NOFe80Se: 477.1228).
colorless liquid (508 mg, 85%). H NMR (500 MHz, CDCl3) δ
7.41 (m, 1H), 7.23 (m, 1H), 7.12 (m, 2H), 3.49 (s, 2H), 2.78 (t, J
) 6.8 Hz, 2H), 2.23 (s, 6H), 1.72 (m, 2H), 1.48-1.16 (m, 6H),
0.86 (t, J ) 6.9 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 139.9,
133.9, 130.4, 129.7, 127.6, 125.5, 64.3, 45.0, 31.3, 29.8, 29.7, 26.8,
22.6, 14.0; HRMS (ESI) m/z 299.1146 (calcd for C15H25N80Se:
299.1146).
Preparation of 1-[[Bis(1-methylethyl)amino]carbonyl]-2-(n-
propylseleno)ferrocene (7c). Propyl selenide 7c was prepared as
described for 7f using [[bis(1-methylethyl)amino]carbonyl]ferrocene
and di-n-propyl diselenide at 0.5 mmol scale. The product yield
Preparation of 2-N,N-Diisopropylbenzamide Hexyl Selenide
(5). n-Butyllithium (3.1 mL of a 1.3 M solution in cyclohexane/
hexane, 4.0 mmol) was added slowly to TMEDA (0.59 mL, 3.9
mmol) in THF (10 mL) at -78 °C under Ar. After 10 min, N,N-
diisopropylbenzamide (616 mg, 3.0 mmol) in THF (4 mL) was
added dropwise via syringe and the resulting solution was stirred
for 1 h at -78 °C. Dihexyl diselenide (1.31 g, 4 mmol) in THF (2
mL) was added via syringe and the resulting mixture was stirred
for an additional 1 h at -78 °C and for 1 h at room temperature.
The reaction mixture was poured into a mixture of ice (25 g) and
brine (20 mL) and the products were extracted with ether (3 × 15
mL). The combined ether extracts were dried over Na2SO4 and
concentrated in vacuo to give a yellow oil. The crude product was
purified via column chromatography on SiO2 eluted with hexanes/
ethyl acetate (9:1) to give 1.00 g (91%) of 5 as a colorless liquid:
1H NMR (500 MHz, CDCl3) δ 7.52 (dd, J ) 6.5, 2.5 Hz, 1H),
7.22 (m, 2H), 7.11 (dd, J ) 6.5, 2.5, 1H), 3.57 (dm, J ) 6.0 Hz,
2H), 2.93 (br d, 2H), 1.68 (m, J ) 7.5 Hz, 1H), 1.62-1.59 (many
signals, 6H), 1.39 (m, J ) 7.0 Hz, 2H), 1.30-1.23 (m, 4H), 1.20
(br d, 3H), 1.06 (br s, 3H), 0.87 (t, J ) 7.0 Hz, 3H); 13C NMR
(125 MHz, CDCl3)δ169.7, 142.7, 133.6, 128.5, 127.2, 127.0, 125.6,
51.0 (br), 45.9 (br), 31.4, 30.2, 29.7, 28.4, 22.7, 20.9, 14.1; IR (film,
NaCl) 1634 cm-1; ESMS (ESI) m/z 392.1454 (calcd for
C19H31NO80Se + Na+: 392.1463).
1
was 197 mg (91%) of 7c as a yellow oil: H NMR (500 MHz,
CDCl3) δ 4.36 (m, 1H), 4.31 (s, 5H), 4.28 (m, 1H), 4.17 (t, J )
2.5 Hz, 1H), 3.92 (br s, 1H), 3.41 (br s, 1H), 2.68 (t, J ) 7.5 Hz,
2H), 1.66 (t, J ) 7.5 Hz, 2H), 1.50 (br s, 6H), 1.07 (br s, 6H), 0.97
(t, J ) 7.5 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 167.2, 94.9,
90.1, 75.0, 73.1, 71.4, 67.4, 67.4, 50.4 (br), 46.0 (br), 31.0, 23.9,
21.0, 14.6; IR (film, NaCl) 1637 cm-1; HRMS (ESI) m/z 458.0656
(calcd for C20H29NOFe80Se + Na+: 458.0656).
Preparation of 1-[[Bis(1-methylethyl)amino]carbonyl]-2-(n-
pentylseleno)ferrocene (7e). Pentyl selenide 7e was prepared as
described for 7f using [[bis(1-methylethyl)amino]carbonyl]ferrocene
and di-n-pentyl diselenide at 1.0 mmol scale. The product yield
1
was 610 mg (60%) of 7e as a yellow oil: H NMR (500 MHz,
CDCl3) δ 4.30 (t, J ) 2.0 Hz, 1H), 4.18 (m, J ) 2.0, 1H), 4.18 (s,
5H), 4.28 (m, 1H), 4.18 (t, J ) 3.0 Hz, 1H), 3.93 (br s, 1H), 3.41
(br s, 1H), 2.70 (t, J ) 7.5 Hz, 2H), 1.68-1.62 (m, 2H), 1.51 (br
s, 1H), 1.43-1.24 (m, 8H), 1.09 (br s, 6H), 0.88 (t, J ) 7.5 Hz,
3H); 13C NMR (125 MHz, CDCl3) δ 167.2, 90.0, 72.9, 72.9, 71.3,
67.4, 67.3, 50.3 (br), 46.0 (br), 32.7, 32.2, 30.3, 28.7, 28.4, 23.1,
22.3, 21.0, 14.0; IR (film, NaCl) 1636 cm-1; HRMS (ESI) m/z
463.1087 (calcd for C23H33NOFe80Se: 463.1071).
Preparation of Ferrocenyl Heptyl Selenide (6). Sodium
borohydride (290 mg, 7.6 mmol) was added in one portion to a
solution of diferrocenyl diselenide (2.00 g, 3.8 mmol) in EtOH (15
mL) cooled to 0 °C under Ar. After the reaction had stirred for
1 h, 1-bromoheptane (1.24 mL, 1,44 g, 7.6 mmol) was added via
syringe at room temperature. The reaction mixture was stirred for
an additional 3 h and poured into water, and the products were
extracted with ether (2 × 15 mL). The combined ether extracts
Preparation of 1-[[Bis(1-methylethyl)amino]carbonyl]-2-(n-
heptylseleno)ferrocene (7g). Heptyl selenide 7g was prepared as
described for 7f using [[bis(1-methylethyl)amino]carbonyl]ferrocene
and di-n-heptyl diselenide at 1.0 mmol scale. The product yield
1
was 396 mg (81%) of 7g as a yellow oil: H NMR (500 MHz,
CDCl3) δ 4.36 (m, 1H), 4.31 (s, 5H), 4.28 (m, 1H), 4.17 (t, J )
3.0 Hz, 1H), 3.93 (br s, 1H), 3.39 (br s, 1H), 2.70 (t, J ) 7.5 Hz,