Synthesis and characterization of a novel chiral azomethine diselenide

Article abstract of DOI:10.1016/j.jorganchem.2005.04.005

The first chiral diselenide 9 having an ortho-azomethine functional group has been synthesized by the reaction of bis(o-formylphenyl) diselenide with the chiral amine R(+)-(1-phenylethylamine). The chiral diselenide 9 was further characterized by derivati

Full text of DOI:10.1016/j.jorganchem.2005.04.005

Journal of Organometallic Chemistry 690 (2005) 3142–3148
www.elsevier.com/locate/jorganchem
Synthesis and characterization of a novel chiral azomethine diselenide
a
a
a,
b
Snigdha Panda , Sanjio S. Zade , Harakesh B. Singh *, Gotthelf Wolmershauser
¨
a
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 4000076, India
b
Fachbereich Chemie, Universita¨t Kaiserslautern, Postfach 3049, Kaiserslautern 67653, Germany
Received 21 November 2004; revised 28 March 2005; accepted 5 April 2005
Available online 17 May 2005
Abstract
The first chiral diselenide 9 having an ortho-azomethine functional group has been synthesized by the reaction of bis(o-formyl-
phenyl) diselenide with the chiral amine R(+)-(1-phenylethylamine). The chiral diselenide 9 was further characterized by derivatizing
it into the corresponding selenenyl halides. The derivatives are characterized by single crystal X-ray diffraction studies. In the solid
state, the bromide derivative 11 shows the strongest Seꢀ ꢀ ꢀN intramolecular interaction. The chiral azomethine diselenide 9 has been
further reduced to afford the diselenide 13. The monoselenide analogues of 9 and 13 have also been synthesized.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Chiral azomthine diselenide; Seꢀ ꢀ ꢀN interaction; Selenenyl halide; Tridentate and tetradentate ligand
1. Introduction
the chiral center to approach the reaction center
during the addition of the selenenylating agent to
the alkene moiety. This results in asymmetric induc-
tion. The Seꢀ ꢀ ꢀheteroatom interactions in such cases,
therefore, not only dictate the molecular structure of
the active selenium reagent so that the reaction pro-
ceeds through a relatively confined transition state
but also increase or decrease the electrophilic reactivity
of the selenium compounds depending upon the nat-
ure of the heteroatom and substituents on the hetero-
atom [5].
Although, a number of chiral diselenides (1–7) with
nitrogen as heteroatom in close proximity to selenium
are known [4f,6], there is no report on a chiral Schiff
base diselenide. In continuation of our work on intra-
molecularly coordinated organochalcogens [7], we re-
port here the synthesis and characterization of a chiral
Schiff base diselenide and related reduced Schiff base tet-
radentate and tridentate ligands incorporating Se and N
as donor atoms and the corresponding selenenyl halide
derivatives Scheme 1.
The increasing usefulness of catalytic and stoichi-
ometric asymmetric synthesis has been demonstrated
for the synthesis of optically active compounds [1],
particularly, biologically active chiral compounds [2].
In this regard, the chiral selenium compounds have
drawn considerable attention and have become
standard reagents for organic synthesis [3]. A variety
of chiral electrophilic selenenylating reagents in asym-
metric reactions, such as methoxyselenenylation,
hydroxyselenenylation, aminoselenenylation and seleno-
cyclization, have been investigated extensively over the
past few years [4]. A common characteristic of all
these reagents described in the literature is the close
proximity of a heteroatom (heteroatom = N, O, S) to
the selenium. The intramolecular nonbonding interac-
tions between selenium and the heteroatom facilitate
*
Corresponding author. Tel.: +91225767190; fax: +91225723480.
E-mail address: chhbsia@chem.iitb.ac.in (H.B. Singh).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.04.005

S. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 3142–3148
3143
O
O
H
H
(i)
Se
O
Se
Cl
H
8
(ii)
Me
Me
Ph
Se
H
N
N
Ph
Se
(VI)
N
H
Me
(iii)
Se
Ph
N
Ph
Se
Ph
Se
N
Cl
Me
Me
10
9
13
(V)
(iv)
Me
Me
N
Ph
N
Ph
Se
Se
I
Br
12
11
(ii) (R)-(+)-1-phenylethylamine, benzene, Aceticacid
(i) Na, Se, THF, HMPA
(iii) SO2Cl2, CH2Cl2
(VI) NaBH4, MeOH
(V) I2, CH2Cl2
(iv) Br2, CH2Cl2
Scheme 1.
Ph
Ph
sodium diselenide. Sodium diselenide was synthesized
in situ by refluxing a mixture of sodium and selenium
in THF in the presence of catalytic amount of naph-
thalene. Syper et al. [8] have reported the synthesis of
the diselenide 8 using the lithium diselenide route and
O
O
Me
O
O
NMe2
NMe2
2
N
Se
Fe
Se
2
R
1
characterized it by mp, IR and H NMR spectroscopy.
R = H, 3
Se
2
2
They have separated the pure diselenide from the crude
product by using column chromatography. In the pres-
ent case, the pure diselenide has been separated from
the product mixture by washing the crude product with
ether, followed by recrystallization from chloroform/
ether (1:1) solution. The optically active tetradentate
azomethine diselenide 9 was obtained by the reaction
of bis(o-formylphenyl) diselenide with (R)-(+)-1-phen-
ylethylamine in the presence of a catalytic amount of
acetic acid for the enhancement of the reaction rate.
The preparative procedure involved separation of
water formed from the reaction by using a Dean-Stark
trap. The unreacted amine was removed from the reac-
tion mixture by washing the product several times with
water. The Schiff base diselenide 9 was obtained as an
orange liquid. The diselenide 9 was further character-
ized by derivatising it into the corresponding selenenyl
= OMe, 4
1
H
N
Me
Se
2
Se
N
2
R
R = OH, 6
= OCOC6H5, 7
5
2. Results and discussion
The precursor bis(o-formylphenyl) diselenide (8) was
prepared by reacting ortho-chlorobenzaldehyde with

3144
S. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 3142–3148
halide derivatives. The compounds 10, 11 and 12 were
obtained as crystalline solids in good yields by reacting
9 with stoichiometric amounts of sulfuryl chloride, bro-
mine and iodine, respectively. Reduction of the Schiff
base diselenide 9 has been carried out using NaBH4
to generate compound 13 which would produce more
stable selenium compound for organic synthesis than
the parent Schiff base ligand 9. The monoselenide ana-
logue 15 (Scheme 2) has also been synthesized by the
reaction of bis(o-formylphenyl) selenide [9] with (R)-
(+)-1-phenylethylamine following a similar procedure
used for the preparation of the corresponding disele-
nide. Reduction of the Schiff base monoselenide (15)
with sodium borohydride afforded the amine com-
pound 16.
are slightly downfield shifted compared to the parent
Schiff base.
As expected in the case of 13, there is absence of the
peak corresponding to the azomethine proton. Also,
there is an upfield shift of the CH and CH3 protons,
which reflects relatively weaker Seꢀ ꢀ ꢀN interaction in
13 compared to that in 9. The presence of NH peak at
2 ppm was confirmed by a D2O exchange experiment.
For 15, the azomethine peak is observed at 8.63,
whereas in case of 16 the azomethine peak is absent.
The 77Se NMR spectra for all the compounds were
recorded in CDCl3 solution. There is a small downfield
shift for diselenide 9 (478 ppm) compared to the precur-
sor diselenide 8 (468 ppm). This probably is due to the
presence of a stronger Seꢀ ꢀ ꢀN nonbonded interaction
compared to Seꢀ ꢀ ꢀO interaction in the latter case. Simi-
larly, in the case of 15 (402 ppm), there is a downfield
shift compared to formyl monoselenide 14 (393 ppm)
[9]. The downfield shift for compound 9 compared to
its reduced analogue 13 (426 ppm) indicates that sp2
nitrogen atoms have stronger Seꢀ ꢀ ꢀN nonbonded inter-
action. This is also observed in the case of 16
(341 ppm). In the case of the selenenyl halides 10–12, a
large deshielding in 77Se chemical shift is observed with
respect to the diselenide 9 and the magnitude of the
downfield shift is according to the electronegativity of
the halide atoms attached to the selenium atom.
The electrospray ionization mass spectra (ESI-MS) of
all the compounds, except 11, do not show the molecu-
lar ion peak. For the chloro and iodo derivatives (10 and
12, respectively) the highest peak is at M ꢁ X at
m/e = 288. In all cases the base peak is at m/e = 184,
which corresponds to C7H6NSe.
The FT IR spectra of all the compounds were re-
corded and are quite informative about the presence of
the (–C@O, –C@N) functional groups and intramolecu-
lar coordination. The carbonyl stretching frequency of
the bis(o-formylphenyl) diselenide (8) was observed at
1692 cmꢁ1. The peak at 1692 cmꢁ1 was split and indi-
cates a significantly different environment for the two
C@O groups. In case of the chiral Schiff base diselenide
9, the carbonyl stretching frequency was absent and a
new peak at 1641 cmꢁ1 for mC@N was observed. In com-
pounds 10–12, the mC@N stretching frequency appeared
at ꢂ1640–1650 cmꢁ1 as weak broad multiplet indicating
the strong coordination of N to Se, thus enhancing the
delocalization of the double bond in the five membered
ring formed by the coordination. In compound 13, as
expected, the mC@N stretching frequency was absent.
For the chiral azomethine monoselenide 15, the C@N
stretching frequency appeared at 1641 cmꢁ1 whereas in
the case of 16, it was absent, which confirmed the com-
plete reduction of the azomethine moiety to the corre-
sponding amine.
The optical rotation values are given with the analyt-
ical data. The optical purity of a representative com-
pound 9 was determined by recording the 1H NMR
spectra in presence of different mole ratios of the chiral
shift reagent tris[3-(heptafluropropyl)hydroxymethyl-
ene-(+)-camphorato]europium(III) [Eu(tfc)3] in CDCl3
from 1:0.25 to 1:1.25 ratio. There was no change in
the resonances of the compound indicating the optical
purity of the compound.
1
The peak at 10.2 ppm in the H NMR spectrum of 8
indicates the presence of the formyl group. For the
Schiff base diselenide 9 and for the related selenenyl ha-
lide derivatives 10–12, the azomethine protons were ob-
served in the region 8.5–9 ppm as sharp singlets. The
peaks for the azomethine protons of selenenyl halides
Me
Me
N
Ph
Ph
N
H
O
Ph
(ii)
(i)
Se
Se
Se
H
N
Ph
Me
N
O
Me
15
16
14
(i) (R)-(+)-1-phenylethylamine , benzene, Acetic acid
(ii) NaBH4, EtOH
Scheme 2.

S. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 3142–3148
3145
Fig. 1. PLUTON view of the compound 10.
Table 1
Significant bond lengths (A) and bond angles (ꢁ) for 10, 11 and 12
176.04(7)ꢁ] allows an effective orbital interaction be-
tween the nitrogen lone pair and r* orbital of the Se–
Cl bond and also easy availability of lone pair of sp2
nitrogen atom towards coordination leads to elongation
of the trans Se–Cl bond and stronger Seꢀ ꢀ ꢀN interaction.
˚
10
11
12
Se(1)-C(1)
N(1)–C(7)
N(1)–C(8)
Se(1)–X(1)
Se(1)–N(1)
1.889(3)
1.275(4)
1.487(4)
2.6097(9)
1.951(3)
1.891(3)
1.274(5)
1.495(5)
2.7767(5)
1.943(3)
1.900(3)
1.284(4)
1.475(5)
2.9868(4)
1.960(3)
˚
In compound 11, the Seꢀ ꢀ ꢀN distance [1.943(3) A] is
the shortest compared to the distances reported for
any selenenyl derivatives. This Seꢀ ꢀ ꢀN distance is much
closer to the sum of the single bond covalent radii of
C(1)–Se(1)–N(1)
C(1)–Se(1)–X (1)
N(1)–Se(1)–X(1)
C(7)–N(1)–Se(1)
C(8)–N(1)–Se(1)
C(2)–C(1)–Se(1)
C(6)–C(1)–Se(1)
83.14(12)
92.91(10)
176.04(7)
114.6(2)
83.21(14)
93.93(11)
177.14(9)
114.9(2)
121.0(3)
127.5(3)
112.3(2)
83.45(13)
95.87(9)
178.46(8)
114.0(2)
119.2(2)
128.0(2)
110.9(3)
˚
˚
Se (1.16 A) and N (0.75 A). The Se–Br bond distance
˚
[2.7767(5) A] is greater than the reported value
˚
for(R)-(4-ethyl)-2-phenyloxazoline [2.661(2) A] [10a]
and bis [3-(4,5-dihydro-4,4-dimethyl-1,3-oxazol-2-yl)-4-
(3,5-dimethylphenyl)-2-naphthyl] selenium bromide
121.0(2)
127.6(2)
112.26(19)
˚
[2.6485(7) A] [7d,10b]. The Seꢀ ꢀ ꢀN–Br angle [177.14(9)ꢁ]
is close to a linear arrangement. In selenenyl iodide 12
˚
The single crystal structures of 10, 11 and 12 have
been determined. These are isostructural and therefore,
the crystal structure of only 10 is discussed in detail.
Only the salient features of 11 and 12 are compared with
10. The PLUTON view of compound 10 is shown in Fig.
1. The significant bond lengths and bond angles of 10,
11 and 12 are given in Table 1. The geometry around
Se is T shaped due to the strong Seꢀ ꢀ ꢀN nonbonded
interaction. In compound 10, the strongest Seꢀ ꢀ ꢀN inter-
the Seꢀ ꢀ ꢀN nonbonding distance [1.960(3) A] is smaller
than the reported Seꢀ ꢀ ꢀN distances for other selenenyl io-
dide compounds [7]. There is no intermolecular interac-
tion between the molecules in the packing diagram of
10, 11 and 12.
3. Experimental
˚
action (1.951(3) A) is observed compared to other
selenenyl chlorides reported in the literature [7]. The
Seꢀ ꢀ ꢀN distance is close to the sum of the covalent radii
3.1. General methods
˚
of Se and N (1.80 A). The Se–Cl bond length
Air-sensitive reactions were carried out under an inert
atmosphere. Solvents were purified and dried by stan-
dard procedures and were freshly distilled prior to use.
All chemicals used, o-chlorobenzaldehyde (sd fine), so-
dium (sd fine), R-(+)-(1-phenylethylamine) (Fluka) and
the chiral shift reagent tris[3-(heptafluropropyl)hydroxy-
methylene-(+)-camphorato]europium(III) (Merck), were
reagent grade and were used as received. Melting points
˚
[2.6097(9) A] is much longer compared to the sum of
˚
the covalent radii (2.16 A). This value is longer than
the Se–Cl distance reported for 2-(4,4-dimethyl-2-phe-
˚
nyloxazolinyl)benzeneselenenyl chloride (2.482(8) A)
˚
[7a]. The Se–Cl bond is longer by 0.128 A than the re-
ported longest trans Se–Cl bond distance [10a]. The al-
most linear alignment of Nꢀ ꢀ ꢀSe–Cl [N(1)–Se–Cl:

3146
S. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 3142–3148
1
were recorded in capillary tubes and are uncorrected. The
elemental analyses were performed on Carlo-Erba model
1106 and Eager 300 EA1112 elemental analyzers. The IR
spectra were recorded as KBr pellets on a Thermo Nico-
C6H6), H NMR (CDCl3): 8.55 (s, CH@N, 2H), 7.87–
7.14 (m, aromatic protons, 18H), 4.68 (q, CHPh, 2H),
1.68 (d, Me, 6H), 13C NMR (CDCl3): 159.51 (imine car-
bon), 144.73, 134.68, 133.31, 131.90, 130.31, 128.50,
128.29, 126.90, 126.80, 125.61 (aromatic carbons),
70.22 (CHPh), 26.54 (Me), 77Se NMR (CDCl3):
478 ppm.
1
let Avatar 320 FTIR spectrometer. H and 13C NMR
spectra were obtained at 400 MHz in CDCl3 on Varian
spectrometer. 77Se NMR spectra were obtained at
95.34 MHz on a Bruker 500 spectrometer. Chemical
shifts are cited with respect to SiMe4 (1H and 13C) and
Me2Se (77Se) as external standard. The enantiomeric pur-
ity of 9 was determined by the integration of the signals in
3.4. Synthesis of bis[o-(R)-(methylbenzyliminomethinyl)-
phenyl] selenenyl chloride (10)
1
the H NMR signal using the chiral shift reagent tris[3-
To a solution of diselenide 9 (0.2 g, 0.34 mmol) in
dichloromethane (25 mL), SO2Cl2 (0.045 g, 0.34 mmol)
in dichloromethane (25 mL) was added drop wise at
0 ꢁC for 1 h. The reaction mixture was stirred for 6 h at
room temperature. Then the solvent was completely
evaporated under vacuum. The viscous product so ob-
tained was triturated with pentane to give a white solid
and the solid was recrystallized from CHCl3/pentane
(1:1) mixture. Yield: 0.1 g, 88%; (Anal. calc. for
C15H15NSeCl: C, 55.67; H, 4.67; N, 4.32. Found: C,
54.98; H, 4.20; N, 3.8.) IR(neat): 1641 cmꢁ1 (C@N
stretching), [a]25 = ꢁ4.34 (c = 1.15, CH2Cl2) MS m/z
288 (M+ ꢁ Cl), 183 (C7H6NSe), 1H NMR (CDCl3):
9.04 (s, CH@N, 1H), 9.04–7.26 (m, aromatic protons,
9H), 5.59 (q, CHPh, 1H), 2.02 (d, Me, 3H), 13C NMR
(CDCl3): 156.52 (imine carbon), 151.68, 139.42, 132.17,
132.07, 129.67, 129.52, 129.44, 126.90, 129.38, 126.78
(aromatic carbons), 64.18 (CHPh), 23.21 (Me), 77Se
NMR (CDCl3): 1004 ppm.
(heptafluropropyl)hydroxymethylene-(+)-camphorato]
europium(III) [Eu(tfc)3]. ESI-MS mass spectra were re-
corded at room temperature on a Q-Tof micro (YA-
105) micromass. Optical rotations were measured by a
JASCO Model DIP 370 digital polarimeter.
3.2. Synthesis of bis(o-formylphenyl) diselenide (8) [8]
Sodium diselenide (50 mmol) was prepared from sele-
nium and sodium in the presence of catalytic amount of
naphthalene in dry THF (50 mL). o-Chlorobenzalde-
hyde (7.02 g, 50 mmol) and HMPA (20 mL) were added
to this solution. After stirring for 12 h at room temper-
ature the reaction mixture was refluxed for 6 h. The mix-
ture was allowed to cool slowly at room temperature.
The solvent was evaporated and the resulting product
was washed with water to remove HMPA. The solid ob-
tained after washing with water, was filtered, dried and
washed with ether several times to separate the monosel-
enide and other side products. The diselenide was ob-
tained as a pure yellow solid and was recrystallized
from CHCl3/ether (1:1) mixture. Yield: 2.5 g, 30%;
m.p. 172 ꢁC (m.p. 172 ꢁC) [8] (Anal. calc. for
C14H10Se2O2: C, 45.65; H, 2.7. Found: C, 45.2; H,
2.78.) IR (KBr): 1692, 1665 cmꢁ1 (C@O) 1H NMR
(CDCl3): 10.2 (s, –CHO, 2H), 7.86–7.26 (m, Ar–H,
12H), 13C NMR (CDCl3): 193 (aldehydic carbon), 136,
135, 134.7, 134.5, 131, 126.5 (aromatic carbons), 77Se
NMR (CDCl3): 468 ppm.
3.5. Synthesis of bis[o-(R)-(methylbenzyliminomethinyl)-
phenyl] selenenyl bromide (11)
The procedure followed was the same as that used for
the preparation of compound 10, except the addition of
Br2 in place of SO2Cl2. Yield: (0.12 g, 96%); (Anal. calc.
for C15H15NSeBr: C, 48.94; H, 3.84; N, 3.81. Found: C,
46.03; H, 3.02; N, 3.06.); IR(neat): 1641 cmꢁ1 (C@N
stretching); [a]25 = ꢁ6.38 (c = 0.47, CH2Cl2); ESI-MS:
m/z 367 (M+), 288 (M+ ꢁ Cl), 183 (C7H6NSe); 1H
NMR (CDCl3, 400 MHz): 8.89 (s, CH@N, 1H), 9.08–
7.26 (m, aromatic protons, 9H), 5.58 (q, CHPh, 1H),
2.00 (d, Me, 3H); 13C NMR (CDCl3,): 156.23 (imine car-
bon), 149.91, 139.24, 132.13, 132.06, 130.36, 129.81,
129.39, 129.30, 129.38, 126.90 (aromatic carbons),
64.20 (CHPh), 23.14 (Me), 77Se NMR (CDCl3,):
1006 ppm.
3.3. Synthesis of bis[o-(R)-(methylbenzyliminomethinyl)-
phenyl] diselenide (9)
Bis(o-formylphenyl) diselenide 8 (1 g, 2.7 mmol) was
refluxed azeotropically in benzene (200 mL), with (R)-
(+)-1-phenylethylamine (0.66 g, 5.4 mmol) and two
drops of acetic acid, using a Dean-Stark trap till the
completion of the reaction (by IR). The mixture was
washed with water (3 · 100 mL) to remove the unre-
acted amine. The remaining water from the organic
layer was removed azeotropically and finally benzene
was evaporated under vacuum to give a yellow viscous
liquid of the Schiff base 9. Yield: 1.07 g, 68%; IR(neat):
1641 cmꢁ1 (C@N stretching), [a]25 = ꢁ250.28 (c = 3.5,
3.6. Synthesis of bis[o-(R)-(methylbenzyliminomethinyl)-
phenyl] selenenyl iodide (12)
The procedure followed was the same as that used for
the preparation of compound 10, except the use of an io-
dine solution in place of SO2Cl2. Yield: 0.13 g, 90%;
(Anal. calc. for C15H15NSeI: C, 43.51; H, 3.4; N, 3.38.

S. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 3142–3148
3147
Found: C, 42.7; H, 2.89; N, 2.97.) IR(neat): 1641 cmꢁ1
(C@N stretching), [a]25 = ꢁ4.34 (c = 1.15, CH2Cl2),
MS m/z 288 (M+ ꢁ I), 183 (C7H6NSe), 1H NMR
(CDCl3): 8.73 (s, CH@N, 1H), 8.95–7.26 (m, aromatic
protons, 9H), 5.37 (q, CHPh, 1H), 2.03 (d, Me, 3H),
13C NMR (CDCl3): 155.17 (imine carbon), 146.68,
139.30, 133.22, 132.45, 132.02, 129.95, 129.46, 129.30,
127.08, 126.96 (aromatic carbons), 64.03 (CHPh),
23.33 (Me), 77Se NMR (CDCl3): 988 ppm.
nyl)phenyl]selenide 15 with NaBH4 in methanol follow-
ing the procedure used for 13. Yield: 65% IR(neat):
1585, 1451 cmꢁ1, [a]25 = 9.4285(c = 3.5, C6H6) 1H NMR
(CD3Cl): 7.31–7.05(m, 18H), 3.70(m, 8H), 1.74(2H,
NH), 1.29(d, 6H), 13C NMR (CDCl3): 145.29, 141.72,
134.29, 132.48, 129.87, 128.43, 128.00, 127.57, 126.93,
126.72 (aromatic carbons), 57.81 (CH2), 52.37 (CH),
24.57 (Me), 77Se NMR (CDCl3): 341 ppm.
4. X-ray structure determination
3.7. Synthesis of bis[o-(R)-(methylbenzylamino-
methinyl)phenyl] diselenide (13)
The diffraction measurements were performed on a
STOE (Darmstadt, Germany) IPDS imaging plate single
crystal diffractometer at room temperature with graph-
To the Schiff base diselenide 9 (0.8 g, 14 mmol) in
ethanol under nitrogen, solid NaBH4 (excess) was
added in small portions. The reaction mixture was
stirred for 4 h and then refluxed for 1 h. Excess etha-
nol was removed under vacuum. To the residue water
(50 mL) was added and the product was extracted
with chloroform. Removal of the solvent afforded vis-
cous yellow oil. Yield: 0.6 g, 74%; IR(neat): 1451,
1491 cmꢁ1; [a]25 = ꢁ5.99 (c = 1, CH2Cl2), MS m/z
286 (M+/2), 183 (C7H6NSe), 1H NMR (CDCl3):
7.76–7.1 (m, aromatic protons, 18H), 3.69–3.81 (m,
CHPh, CH2Ph, 6H), 1.40 (d, J = 6.5 Hz, Me, 6H),
13C NMR (CDCl3): 144.5, 139.77, 132.98, 131.96,
129.38, 128.06, 126.96, 126.55, 126.44, (aromatic car-
bons), 57.64 (CH2Ar), 52.36 (CHPh), 23.96 (Me),
77Se NMR (CDCl3): 426 ppm.
˚
ite-monochromated Mo Ka radiation (k = 0.7107 A).
The structures were solved by direct methods and full-
matrix least-squares refinement on F2 (program
SHELXL-97) [11]. Hydrogen atoms were localized by geo-
metrical means. A riding model was chosen for refine-
ment. The isotropic thermal parameters of the H
atoms were fixed at 1.5 times (CH3 groups) or 1.2 times
Ueq (Ar–H) of the corresponding C atom. Some details
of the data collection and refinement are given in
Table 2.
Crystallographic data for the structural analyses
have been deposited with the Cambridge Crystallo-
graphic Data Centre; CCDC Nos. 254801–254803
for compounds 10, 11 and 12, respectively. Copies
of this information may be obtained free of the charge
3.8. Synthesis of bis[o-(R)-(methylbenzylimino-
methinyl)phenyl] selenide (15)
Table 2
Crystal data and structure refinement of 10, 11 and 12
10
15H14ClNSe C15H14BrNSe C15H14INSe
322.68 367.14 414.13
Orthorhombic Orthorhombic Orthorhombic
11
12
Bis(o -formylphenyl)selenide 7 was refluxed azeotropically
in benzene (200 mL), with (R)-(+)-1-phenylethylamine
and two drops of acetic acid, using a Dean-Stark trap till
the completion of the reaction (by IR). The resulting
reaction mixture was washed with water (3 · 100 mL)
to remove the unreacted amine. The remaining water
from the organic layer was removed azeotropically and
finally benzene was evaporated under vaccum to give a
viscous yellow oil of the Schiff base. Yield: 80%
IR(neat): 1641 cmꢁ1(C@N stretching), [a]25 = 42.826
(c = 4.6, CHCl3) 1H NMR (CD3Cl): 8.63 (CH@N,
2H), 7.07–7.82 (m, C6H5, C6H4, 18H), 4.47(q, CHPh,
2H), 1.53 (d, Me, 6H), 13C NMR (CDCl3): 160
(imine carbon), 145, 136.63, 134.07,130.87, 130.40,
128.53, 127.42, 126.91, 126.86 (aromatic carbon atoms),
70.16 (CHPh), 25.95 (Me), 77Se NMR (CDCl3):
402 ppm.
Empirical formula
Fw
C
Crystal system
Space group
Unit cell dimensions
P212121
P212121
P212121
˚
a (A)
10.9277(7)
11.1710(8)
11.3708(10)
90
11.1543(7)
11.1669(8)
11.5569(10)
90
10.0377(7)
11.6427(9)
12.8939(11)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
90
90
90
90
3
˚
V (A )
1388.07(18)
4
1439.52(19)
4
1506.9(2)
4
Z
Temperature (K)
Absoption
coefficient
293(2)
2.878
293(2)
5.366
293(2)
4.524
(mmꢁ1
)
Observed
reflections
[I > 2r]
2944
2978
3077
Final R(F)
[I > 2r]a
0.0270
0.0257
0.0460
0.0183
0.0380
3.9. Synthesis of bis[o-(R)-(methylbenzylamino-
methinyl)phenyl] selenide (16)
wR(F2) indices
[I > 2r]
0.0563
P
a
Definition:
R(F0) = jjFoj ꢁ jFcjj/RjFoj
and
wRðF 2oÞ ¼
The compound was prepared as an yellow oil by the
reduction of the bis[o-(R)-(methylbenzyliminomethi-
n
o
1=2
P
P
2
2
wðF 2o ꢁ F c2Þ ꢃ= ½wðF 2c Þ
.

3148
S. Panda et al. / Journal of Organometallic Chemistry 690 (2005) 3142–3148
(g) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F. Marini,
L. Bagnoli, A. Temperini, Tetrahedron: Asymmetry 11 (2002)
4645;
from The Director, CCDC, 12 Union Road, Cam-
bridge, CB2 1 EZ, UK (fax: +44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk.
ac.uk).
or
http://www.ccdc.cam.
(h) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F. Marini,
L. Bagnoli, A. Temperini, Chem. Eur. J. 8 (2002) 1118;
(i) L. Uehlin, G. Fragale, T. Wirth, Chem. Eur. J. 8 (2002)
1125;
(j) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F. Marini,
L. Bagnoli, A. Temperini, Angew. Chem., Int. Ed. Engl. 42
(2003) 3131;
Acknowledgments
We are grateful to the Department of Science and
Technology (DST), New Delhi.
(k) S.S. Khokhar, T. Wirth, Angew. Chem. Int. Ed. 43 (2004)
631.
[5] (a) T. Wirth, G. Fragale, M. Spichty, J. Am. Chem. Soc. 120
(1998) 3376;
(b) X. Wang, K.N. Houk, M. Spichty, T. Wirth, J. Am. Chem.
Soc. 121 (1999) 8567;
References
(c) M. Spichty, G. Fragale, T. Wirth, J. Am. Chem. Soc. 122
(2000) 10914.
[1] I. Ojima (Ed.), Catalytic Asymmetric Synthesis, Wiley, New York,
2000, p. 864.
[6] (a) K. Fujita, M. Iwaoka, S. Tomoda, Chem. Lett. (1994) 923;
(b) S. Fukuzawa, Y. Kasugahara, S. Uemura, Tetrahedron Lett.
35 (1994) 9403;
[2] (a) R. Noyori, Asymmetric Catalysis in Organic Synthesis, John
Wiley, New York, 1994;
(c) T. Wirth, Tetrahedron Lett. 36 (1995) 7849;
(d) C. Santi, G. Fragale, T. Wirth, Tetrahedron: Asymmetry 9
(1998) 3625;
(b) J. Seyden-Penne, Chiral Auxiliaries and Ligands in the
Asymmetric Synthesis, John Wiley, New York, 1995;
(c) D.J. Ager, M.B. East, Asymmetric Synthetic Methodology,
CLC Press, New York, 1996.
(e) M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F. Marini,
L. Bagnoli, A. Temperini, Tetrahedron: Asymmetry 11 (2000)
4645.
[3] (a) K.C. Nicolaou, N.A. Petasis, Selenium in Natural Products
Synthesis, CIS, Philadelphia, 1984;
[7] (a) G. Mugesh, A. Panda, H.B. Singh, R.J. Butcher, Chem. Eur.
J. 5 (1999) 1411;
(b) C. Paulmier, Selenium Reagents and Intermediates in Organic
Synthesis, Pergamon Press, Oxford, 1986;
(b) G. Mugesh, H.B. Singh, Acc. Chem. Res. 35 (2002)
226;
(c) D. Liotta (Ed.), Organoselenium Chemistry, Wiley, New
York, 1987;
(c) S. Kumar, K. Kandasamy, H.B. Singh, G. Wol-
mersha¨user, R.J. Butcher, Organometallics 23 (2004) 4199;
(d) K. Kandasamy, S. Kumar, H.B. Singh, R.J. Butcher,
K.T. Holman, Eur. J. Inorg. Chem. (2004) 1014;
(e) S. Kumar, K. Kandasamy, H.B. Singh, R.J. Butcher,
New. J. Chem. 28 (2004) 640.
(d) S. Patai, Z. Rappoport (Eds.), The Chemistry of Organic
Selenium and Tellurium Compounds, vols. 1–2, Wiley, New York,
1986–1987;
(e) T.G. Back (Ed.), Organoselenium Chemistry: a Practical
Approach, Oxford University Press, New York, 1999;
(f) T. Wirth (Ed.), Organoselenium Chemistry: Modern Develop-
ment in Organic Chemistry, Springer-Verlag, Berlin, 2000.
[4] (a) Reviews T. Wirth, Tetrahedron 55 (1999) 1;
(b) T. Wirth, Angew. Chem., Int. Ed. Engl. 39 (2000) 3740;
(c) Y. Nishibayashi, S. Uemura, Top. Cur. Chem. 208 (2000) 201;
(d) L. Uehlin, T. Wirth, Org. Lett. 3 (2001) 2931;
(e) M. Uchiyama, M. Oka, S. Harai, A. Ohta, Tetrahedron Lett.
42 (2001) 1931;
[8] L. Syper, J. Mlochowski, Tetrahedron 44 (1988) 6119.
[9] A. Panda, S.C. Menon, H.B. Singh, R.J. Butcher, J. Organomet.
Chem. 623 (2001) 87.
[10] (a) G. Mugesh, H.B. Singh, R.J. Butcher, Tetrahedron: Asym-
metry 10 (1999) 237;
(b) A. Panda, G. Mugesh, H.B. Singh, R.J. Butcher, Organomet-
allics 18 (1999) 1986.
[11] G.M. Sheldrick, SHELX 97; Program for Crystal Structure Refine-
ment, University of Go¨ttingen, Germany, 1997.
(f) T.G. Back, Z. Moussa, M. Parvez, J. Org. Chem. 67 (2002)
499;