Addition of nitrile oxides to germyl-substituted ethylenes

Article abstract of DOI:10.1016/S0022-328X(98)00419-7

The reactions of [2+3] cycloaddition of nitrile oxides to mono- and 1,2-disubstituted germylalkenes proceed regioselectively and resulted 5-Ge-substituted isoxazolines-2 from triethylvinyl- and triethylallylgermane and 4-Ge-isomers from β-triorganylgermyl

Full text of DOI:10.1016/S0022-328X(98)00419-7

Journal of Organometallic Chemistry 558 (1998) 155–161
Addition of nitrile oxides to germyl-substituted ethylenes
E. Lukevics *, P. Arsenyan, S. Belyakov, J. Popelis
Lat6ian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Lat6ia
Received 5 November 1997
Abstract
The reactions of [2+3] cycloaddition of nitrile oxides to mono- and 1,2-disubstituted germylalkenes proceed regioselectively
and resulted 5-Ge-substituted isoxazolines-2 from triethylvinyl- and triethylallylgermane and 4-Ge-isomers from i-trior-
ganylgermylstyrene and ethyl triorganylgermylacrylates. In the latter case the reaction occurs stereospecifically: Z-germylalkenes
give cis-, while E-germylalkenes yield trans-4,5-substituted isoxazolines. The structure of products obtained was determined by
1H-NMR spectroscopy and for 11a confirmed by single-crystal X-ray analysis. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Germanium; Hydrogermylation; Cycloaddition; Isoxazolines-2; X-ray structure
2. Results and discussion
1. Introduction
Alkenyl- and alkynyl germanes have been involved in
various [2+3] cycloaddition reactions. The addition of
diazoalkanes to unsaturated germanes resulting in
germyl-substituted pyrazoles and pyrazolines has been
described [1,2]. Germylacetylenes add organic azides to
give 1,2,3-triazoles [3]. The interaction of inorganic
azides with germanium containing h,i-acetylenic alde-
hydes and aldimines [4] has been studied as well. In all
cases the mixture of regioisomers has been obtained.
However, up to now the reaction of nitrile oxides
with alkenylgermanes has not been studied.
2.1. Interaction of nitrile oxides with
triethyl6inylgermane and triethylallylgermane
It has been found that triethylvinylgermane and tri-
ethylallylgermane readily react with nitrile oxides in the
cycloaddition reaction affording regiospecifically the
corresponding 5-germyl-substituted isoxazolines-2 with
good yields (42–73%).
The direction of cycloaddition of nitrile oxides to
alkenylsilanes depends on the type of a substituent at
the double bond [5]. To find out the regularities of this
reaction in the series of alkenylgermanes we have stud-
ied the addition of nitrile oxides to triethylvinyl and
triethylallylgermane, i-triorganylgemylstyrenes and
ethyl triorganylgermylacrylates.
The reactions with triethylvinylsilane proceed
analogously.
Nitrile oxides were obtained using two methods of
generation: (1) from the primary nitroalkanes in the
presence of phenylisocyanate and the catalytic amount
of triethylamine; (2) from hydroxamic acid chlorides in
the presence of bases as acceptors of hydrogen chloride.
Following the first method the reaction was carried
out in benzene dropping nitroethane with the catalytic
amount of triethylamine to the mixture of alkenylger-
* Corresponding author. Fax: +371 7821038.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00419-7

156
E. Luke6ics et al. / Journal of Organometallic Chemistry 558 (1998) 155–161
2
mane, double equivalent of phenylisocyanate and 1 ml
triethylamine. Release of CO2 and precipitation of
diphenylurea evidenced for the beginning of the reac-
tion. The addition of nitrile oxide to germylalkene is
considered as a terminal stage of the reaction. There-
fore, it is extremely important to drop nitroethane
slowly to avoid the formation of furoxan.
The second method appears to be convenient as well,
but there is still one drawback in this method—chlori-
nation of aldoximes. During the chlorination of benzal-
doximes the side reaction, chlorination of the ring,
often occurs. To avoid any side reactions N-chlorosuc-
cinimide was used for chlorination in dimethylfor-
mamide. The addition reaction was carried out in ether
dropping the solutions of benzhydroxamic acid chloride
to the mixture of alkenylgermane and the equivalent
amount of triethylamine. The precipitation of triethy-
lamine hydrochloride marks the beginning of the
reaction.
Hd at l 1.30 ppm: (dd, J=6.1 Hz, coupling with Hd,
3J=13.3 Hz, coupling with Ha) and He at 1.32 ppm:
2
3
(dd, J=6.1 Hz, coupling with He, J=13.3 Hz, cou-
pling with Ha). Signals of protons Ha and Hb are
assigned analogously to Ha and Hb in compounds 1
and 3: Ha at l 2.46 ppm: (ddq, J=1.09, 9.15 and 16.57
Hz), Hb at 2.94 ppm: (ddq, J=1.09, 9.6 and 16.57 Hz).
The signal of Hc proton is shifted down field and
appears at l 4.96 ppm (m).
Polarization of the vinyl group in triethylvinylger-
mane and triethylallylgermane is opposite and, conse-
quently, one can expect the different regioselectivity of
nitrile oxides addition, while it has been proved experi-
mentally that the addition occurs analogously. Addi-
tion of benzonitrile oxide to 3,3-dimethylbutene
proceeds in the same direction affording 3-phenyl-5-t-
butylisoxazoline-2 [5]. Trimethylvinyl- and trimethylal-
lylsilane in [2+3]-cycloaddition reactions with nitrile
oxides also give only one product 5-Si-substituted isox-
azoline-2 [5].
According to GLC and mass-spectroscopic data only
one product is obtained in the reactions of cycloaddi-
The addition to terminal alkenylsilanes proceeds re-
giospecifically: the oxygen atom always attacks the
more substituted carbon atom. The relative reactivity of
the alkenylsilanes in cycloaddition of benzonitrile oxide
decreases at the insertion of the methylene groups
between silicon and the double bond [6].
1
tion (Table 1). H-NMR data evidence that 5-triethylsi-
lyl(germyl)-substituted isoxazoline is formed. The
signals of two protons (Ha and Hb) in 4 position of
isoxazoline appear in the spectrum of compound 1: Ha
4
at l 2.53 ppm: (ddq, J=0.65 Hz, coupling with pro-
2
tons of the methyl group in 3 position, J=13.3 Hz–
3
coupling with Hb, J=15.91 Hz, coupling with Hc) and
2.2. Hydrogermylation of acetylenes with trisubstituted
4
3
Hb at l 2.97 ppm: (ddq, J=0.65 Hz, J=10.9 Hz,
3J=15.91 Hz). Hc in 5 position resonates in lower field
as one of the substituents is an oxygen atom l: 3.95
germanes
To obtain i-germyl-substituted ethylenes necessary
for the investigation of cycloaddition reaction the hy-
drogermylation of the substituted acetylenes with trior-
ganylgermanes has been used.
3
3
ppm: (dd, J=10.9 Hz, coupling with Hb, J=15.91
Hz–with Ha).
1H-NMR data for compound 3 are similar: Ha at l
2.8 ppm: (ddq, J=0.2 Hz, coupling with protons of
the methyl group in 3 position, J=14.2 Hz, coupling
with Hb, J=14.2 Hz, coupling with Hc); Hb at l 3.09
ppm: (ddq, J=0.2 Hz, coupling with protons of the
methyl group in 3 position, J=10 Hz, coupling with
4
Triethyl(phenyl)germane adds to the substituted
acetylenes in the presence of Speier’s catalyst (0.1 M
solution H2PtCl6 ·6H2O in absolute isopropyl alcohol).
The reaction with triethylgermane was carried out with-
out solvent, while diethyl ether was used as a solvent in
the hydrogermylation with triphenylgermane. The reac-
tions of triethylgermane with phenylacetylene and ethyl
propiolate were exothermic, but to initiate the hy-
drogermylation with triphenylgermane some heating
was needed.
3
3
4
2
3
Hb, J=14.2 Hz, coupling with Hc). Proton Hc in 5
position resonates at l 4.16 ppm: (dd, 3J=10 Hz,
3
coupling with Hc, J=14.2 Hz, with proton Ha).
1H-NMR data for compound 5 differ to some extent
due to the methylene group in 5 position. Signals of the
methylene protons (Hd, He) appear in the higher fields:
Table 1
5-Ge(Si)-substituted isoxazolines-2
Number
R
n
M
Yield (%)
1
2
3
4
5
6
Me
Ph
Me
Ph
Me
Ph
0
0
0
0
1
1
Si
Si
Ge
Ge
Ge
Ge
54
76
45
73
42
63

E. Luke6ics et al. / Journal of Organometallic Chemistry 558 (1998) 155–161
157
Table 2
Isomers ratio in the hydrogermylation reaction (GLC data)
Number
R
R%
Z (%)
E (%)
h (%)
7a
7b
8a
8b
Et
Et
Ph
Ph
COOEt
Ph
COOEt
Ph
14
10
10
9
34
58
31
43
52
32
59
48
h- And i-isomers were formed approximately in
equal amounts, while i-(E)-isomer was formed pre-
dominantly if compared with i-(Z)-isomer (Table 2).
2.3. Interaction of nitrile oxides with i-(E,Z)-
germylsubstituted ethylenes
i-(E,Z)-Germyl-substituted ethylenes react with ni-
trile oxides, generated by the dehydration of ni-
troethane (nitropropane) with phenylisocyanate in the
presence of the catalytic amount of triethylamine in
benzene (Mukaiyama’s method) [7], and benzonitrile
oxide, generated by the dehydrohalogenation of ben-
zhydroxamic acid chloride with triethylamine in ether,
affording cis- or trans-4-germyl-substituted isoxazoli-
nes-2 (Table 3):
Fig. 1. Molecular structure of ethyl ester of 3-methyI-4-
triphenygermyI-5-isoxazoline-2-carboxylic acid
According to 1H-NMR spectroscopic data 4-tri-
ethyl(phenyl)germyl- substituted isoxazolines are
formed. For compound 9a the signal of proton Ha in
position 4 appears at l 2.73 ppm (dd, 4J=1.8 Hz,
coupling with protons of the methyl group in 3 posi-
3
tion, J=5 Hz, coupling with Hb). The signal at l 5.44
ppm (d, J=5 Hz) was assigned to the proton Hb in 5
position of isoxazoline, as 5-carbon is linked with an
oxygen atom and phenyl group.
The structure of 4-germyl-substituted isoxazoline-2
for compound 11a is confirmed by X-ray diffraction
analysis. A perspective view of the molecule 11a with
the atom labels is shown in Fig. 1. The izoxazoline ring
of 11a has the envelope conformation. The dihedral
angle between O1, N2, C3, C4 plane and the triangle
O1, C5, C4 is equal 171.5(4)°. Atom C5 deviates from
Compounds 9a, 9b, 10a and 10b are viscous liquids.
They are gradually oxidized under storage. Their color
changes from colorless to light orange. Compounds
11a, 11b are white crystalline substances stable to mois-
ture and light.
˚
O1, N2, C3, C4 plane by 0.131(6) A; the displacement
˚
of C6 from the plane is 0.022(10) A. The
triphenylgermyl and ethoxycarbonyl substituents in re-
gard to C4–C5 bond are partially eclipsed: the torsion
angle Ge1–C4–C5–C7 is 123.4(5)°, the molecule has
+anti-clynal form in accordance with Klyne and
Prelog nomenclature [8]. Table 5 lists the bond lengths
and the values of valence angles for molecule 11a.
According to 1H-NMR only Z-isomer of, i-tri-
ethyl(phenyl)germylstyrene reacted with nitrile oxides
affording cis-cycloadduct. It is confirmed by the spin–
According to GLC and mass-spectroscopic data only
one product is resulted from [2+3]-cycloaddition reac-
tions. Nitrile oxide reacted with only one of the iso-
mers. After the separation of the reaction mixture in
each case the product and the unreacted second isomer
were obtained.
Table 3
4-Ge-substituted isoxazolines-2
3
spin coupling constants of Ha and Hb protons: J=5.0
Number
R
R%
R%%
Isomer
Yield(%)
Hz for compounds 9a and 9b and 3J=3.2 Hz for
compound 9c. The cycloaddition of nitrile oxides to
ethyl i-triethyl(phenyl)germylacrylate occurred only
with E-isomer giving trans-product; the spin–spin cou-
pling constants 3J=16 Hz (10a), 14.8 Hz (10b), 13.3 Hz
(11a), 12.86 Hz (11b) support this fact.
9a
9b
9c
10a
10b
11a
11b
Et
Et
Et
Et
Et
Ph
Ph
Ph
Ph
Ph
COOEt
COOEt
COOEt
COOEt
Me
Et
Ph
Me
Et
cis
cis
cis
trans
trans
trans
trans
57
48
57
78
74
94
90
Me
Et
h-Ge-substituted ethylenes under the same reaction
conditions did not react with nitrile oxides obviously

158
E. Luke6ics et al. / Journal of Organometallic Chemistry 558 (1998) 155–161
The addition of nitrile oxide to ethyl i-trans-tri-
ethylsilylacrylate proceeds regiospecifically to give
trans-4-triethylsilyl-substituted isoxazoline-2 [4].
It may be concluded that during the reactions of
[2+3] cycloaddition of nitrile oxides to 1,2-disubsti-
tuted ethylenes the oxygen attacks the most electropos-
itive carbon atom of the double bond.
In the reactions with i-triethylgermylstyrene and
ethyl i-triethylgermylacrylate the oxygen of nitrile ox-
ide also attacks the carbon atom bearing phenyl- or
ethoxycarbonyl substituents affording 4-Ge-substituted
isoxazolines-2.
due to the steric hindrance at the h-carbon atom of the
double bond.
A mixture of regioisomers is usually obtained in
[2+3] cycloaddition reactions of nitrile oxides with
1,2-disubstituted alkenes [9,10], although electron-do-
nating amino [11] and alkoxy [12] substitutents tend to
orientate the cycloaddition so that they are at 5 posi-
tion in the cycloadducts. Acyl [13,14] and sulfinyl [15]
substituents direct the oxygen of the nitrile oxide so
that they are at 4 position of the cycloadduct [16]. The
combined effects of the alkoxy and acyl substitutents
resulted in the high regioselectivity of nitrile oxides
addition to i-(E)-methoxyvinylphenylketone [17]. 4-
isomer appears also in the case of interaction of acry-
lates and nitrile oxides, the reaction results in 4% of
4-isomer and 96% of 5-isomer [18].
3. Experimental
1H-NMR spectra were recorded on a Bruker WH-90/
DS (90 MHz) and an AM360/DS (360.1 MHz) instru-
ments at 303 K with TMS as internal standard. Mass
spectra were recorded on a Kratos MS-25 apparatus
(70 eV). GLC analysis was perfomed on a Varian 3700
instrument equipped with flame-ionizing detector using
a capilar column 5 m×0.53 mm, df=2.65 v, HP-1.
Carrier gas-nitrogen.
The oxygen of nitrile oxides attacks i-carbon atom
of the double bond, e.g. in N-substituted indoles [19],
uracils [20], i-(E)-methoxyvinylphenylketone [17] and
2-ethyl-2-crotyl-1,3-dithiane-1-oxide [16].
Table 4
Atomic coordinates and equivalent isotropic temperature factors*
The melting points were determined on a ‘Digital
melting point analyzer’ (Fisher), the results are given
without correction.
(with e.s.d.’s) for 11a
Atom
x
y
z
Beq
Ge1
O1
N2
C3
C4
C5
C6
C7
O8
0.24179(4)
−0.0707(4)
−0.0389(4)
0.0389(5)
0.0734(4)
−0.0135(5)
0.0877(8)
−0.1031(5)
−0.1930(4)
−0.0691(4)
−0.1412(7)
−0.0804(11)
0.2845(5)
0.2476(6)
0.2867(7)
0.3672(7)
0.4060(6)
0.3647(5)
0.2575(4)
0.2379(6)
0.2549(7)
0.2922(6)
0.3082(8)
0.2904(7)
0.3451(4)
0.3279(5)
0.4079(6)
0.5051(6)
0.5242(6)
0.4452(5)
0.08588(5)
−0.0623(4)
−0.0502(5)
0.0411(6)
0.1063(5)
0.0397(6)
0.0774(11)
0.1357(7)
0.1637(7)
0.1872(5)
0.2936(9)
0.3313(13)
−0.1005(5)
−0.1952(6)
−0.3256(6)
−0.3615(8)
−0.2726(7)
−0.1422(6)
0.1739(6)
0.1099(7)
0.1731(9)
0.3009(9)
0.3691(8)
0.3059(7)
0.1694(5)
0.2998(6)
0.3622(7)
0.2929(8)
0.1623(8)
0.1025(6)
0.38986(3)
0.3068(3)
0.2456(3)
0.2565(3)
0.3275(3)
0.3569(3)
0.2003(4)
0.3644(3)
0.3184(3)
0.4283(2)
0.4424(4)
0.5192(5)
0.4061(3)
0.3513(3)
0.3623(4)
0.4265(4)
0.4808(4)
0.4705(3)
0.4798(3)
0.5349(3)
0.5986(3)
0.6093(4)
0.5540(4)
0.4896(4)
0.3466(2)
0.3210(3)
0.2954(3)
0.2946(4)
0.3187(3)
0.3446(3)
0.0361 (2)
0.0795(14)
0.0608(14)
0.0460(13)
0.0390(12)
0.0497(14)
0.074(2)
3.1. X-Ray structure determination of compound 11a
Monocrystals of compound 11a were grown from
petroleum ether. The crystals (0.25×0.30×0.50mm)
were measured on a Syntex P21, four-circle computer
controlled single-crystal difractometer with graphite-
0.061(2)
0.116(2)
˚
monochromated Mo–Kh (u=0.71069 A) radiation; lat-
O9
0.0726(13)
0.082(2)
0.101 (3)
0.0425(12)
0.060(2)
0.071(2)
0 070(2)
0.069(2)
tice parameters were refined from 18 reflections with
30B2qB35°. A total of 4028 unique reflection intensi-
ties were collected at room temperature using the q/2q
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
scan technique up to 2qmax=50° (sin q/u=0.595 A−1);
˚
one standard reflection showed no significant decay;
Lorentz and polarization corrections were applied to
the data.
0.055(2)
Crystallographic data for 11a are: monoclinic; a=
0.0428(13)
0.061 (2)
0.076(2)
0.074(2)
0.082(2)
˚
12.080(2), b=10.011(2), c=20.072(3) A, i=
3
−1
˚
110.52(1)°; V=2273.3(6) A , Z=4, v=1.37 mm
,
D
calc=1.344(1) g cm−3; F(000)=952; space group
P21/c. For crystal structure solution, the initial phases
of ten strong reflections were determined by the maxi-
mum determinant method [21]. The phase values ob-
tained were introduced into the starting set of the
MULTAN program [22]. Two variants were calculated,
one of them yielding the structure model. The structure
was refined by least squares technique in the full matrix
approximation with anisotropic temperature factors.
The hydrogen atoms were found from different synthe-
sis and refined isotropically. The final goodness of fit
0.067(2)
0.0390(12)
0.0451(13)
0.062(2)
0.072(2)
0.063(2)
0.0471(14)
2
˚
Beq (A ) calculated from anisotropic thermal parameters as Beq
=
8y2D1u/3 where Du is a determinant of the Uij matrix in orthogonal
space.

E. Luke6ics et al. / Journal of Organometallic Chemistry 558 (1998) 155–161
159
Table 5
3.2.2. 3-Methyl-5-triethylsilylisoxazoline-2 (1),
b.p.=102°C/3mm
˚
Bond lengths (A) and angles (°) with e.s.d.’s for molecule 11a (H
atoms not involved)
1H-NMR (360.1 MHz,CDCl3/TMS) l (ppm): 0.65
(6H, q, J=8.06 Hz); 0.99 (9H, t, J=8.06 Hz); 2.02
(3H, dd, J=0.66 Hz, J=1.09 Hz); 2.53 (1H, ddq,
J=0.65, 13.3, 15.91 Hz); 2.97 (1H, ddq, J=0.65, 10.9,
15.91 Hz); 3.95 (1H, dd, J=10.9, 15.91 Hz).
Ge1ꢀC12
Ge1ꢀC24
Ge1ꢀC18
Ge1ꢀC4
O1ꢀN2
O1ꢀC5
N2ꢀC3
C3ꢀC4
C3ꢀC6
C4ꢀC5
C5ꢀC7
C7ꢀ08
C7ꢀO9
1.933(5)
1.942(5)
1.957(5)
1.990(5)
1.415(6)
1.430(7)
1.273(7)
1.488(7)
1.490(9)
1.526(7)
1.494(9)
1.186(7)
1.308(7)
1.464(8)
1.506(12)
1.381(7)
C12ꢀC13
C13ꢀC14
C14ꢀC15
C15ꢀC16
C16ꢀC17
C18ꢀC19
C18ꢀC23
C19ꢀC20
C20ꢀC21
C21ꢀC22
C22ꢀC23
C24ꢀC25
C24ꢀC29
C25ꢀC26
C26ꢀC27
1.400(8)
1.380(8)
1.362(10)
1.358(10)
1.387(8)
1.369(7)
1.374(8)
1.376(9)
1.349(10)
1.372(10)
1.387(9)
1.391(7)
1.395(7)
1.392(8)
1.368(9)
1.386(10)
1.373(8)
120.5(4)
121.9(4)
121.2(6)
119.4(7)
121.2(7)
119.5(6)
121.5(6)
117.2(5)
123.1(4)
119.7(4)
121.6(7)
121.1(7)
118.5(7)
120.5(7)
121.0(6)
117.3(5)
122.2(4)
120.4(4)
121.6(6)
119.1(6)
120.8(6)
119.4(6)
121.7(6)
GC MS(70 eV, m/z): 199 [M+], 197, 185, 169, 157,
128(100), 114(12), 100(60), 86(39), 58(20), 43(13), 39(8).
3.2.3. 3-Methyl-5-triethylgermylisoxazoline-2 (3),
b.p.=68°C/1mm
1H-NMR (90 MHz, CDCl3/TMS) l (ppm): 0.71
(15H, m); 2.04 (3H, t, J=0.2 Hz); 2.80 (1H, ddq,
J=0.2, 10, 14.2 Hz); 3.09 (1H, ddq, J=0.2, 10, 14.2
Hz); 4.16 (1H, dd, J=10, 14.2 Hz).
O9ꢀC10
C10ꢀC11
C12ꢀC17
C27ꢀC28
C28–C29
GC MS(70 eV, m/z): 218, 217, 216 [M+-29], 215,
214, 213, 212, 175(22), 173(16), 171 (12), 161 (29),
160(15), 159(23), 157(17), 135(20), 133(100), 132(28),
131 (79), 129(57), 117(10), 107(16), 105(80), 104(20),
103(81), 101(67), 99(19), 91(13), 89(15), 87(12), 77(15),
75(26), 74(15), 73(22), 71(11), 56(10), 42(10), 41(56).
C12ꢀGe1ꢀC24
C12ꢀGe1ꢀC18
C24ꢀGe1ꢀC18
C12ꢀGe1ꢀC4
C24ꢀGe1ꢀC4
C18ꢀGe1ꢀC4
N2ꢀO1ꢀC5
C3ꢀN2ꢀO1
N2ꢀC3ꢀC4
N2ꢀC3ꢀC6
C4ꢀC3ꢀC6
108.4(2)
110.2(2)
110.4(2)
111.0(2)
110.5(2)
106.3(2)
109.8(4)
108.7(4)
115.0(5)
120.5(6)
124.4(6)
100.3(4)
116.0(4)
113.7(4)
110.0(5)
105.5(4)
112.3(5)
123.9(6)
124.7(6)
111.3(5)
118.2(5)
1105.6(7)
117.1(5)
C17ꢀC12ꢀGe1
C13ꢀC12ꢀGe1
C14ꢀC13ꢀC12
C15ꢀC14ꢀC13
C16ꢀC15ꢀC14
C15ꢀC16ꢀC17
C16ꢀC17ꢀC12
C19ꢀC18ꢀC23
C19ꢀC18ꢀGe1
C23ꢀC18ꢀGe1
C18ꢀC19ꢀC20
C21ꢀC20ꢀC19
C20ꢀC21ꢀC22
C21ꢀC22ꢀC23
C18ꢀC23ꢀC22
C25ꢀC24ꢀC29
C25ꢀC24ꢀGe1
C29ꢀC24ꢀGe1
C24ꢀC25ꢀC26
C27ꢀC26ꢀC25
C26ꢀC27ꢀC28
C29ꢀC28ꢀC27
C28ꢀC29ꢀC24
3.2.4. 3-Methyl-5-triethylgermylmethylisoxazoline-2
(5), b.p.=92°C/1mm
1H-NMR (360.1 MHz,CDCl3/TMS) l (ppm): 0.78
(6H, q, J=7.68 Hz); 1.03 (9H, t, J=7.68 Hz); 1.10
(1H, dd, J=6.1, 13.3 Hz); 1.32 (1H, dd, J=6.1, 13.3
Hz); 1.97 (3H, t, J=1.09 Hz); 2.46 (1H, ddq, J=1.09,
9.15, 16.57 Hz); 2.94 (1H, ddq, J=1.09, 9.6, 16.57 Hz);
4.96(1H, m).
C3ꢀC4ꢀC5
C3ꢀC4ꢀGe1
C5ꢀC4ꢀGe1
O1ꢀC5ꢀC7
O1ꢀC5ꢀC4
C7ꢀC5ꢀC4
O8ꢀC7ꢀO9
O8ꢀC7ꢀC5
O9ꢀC7ꢀC5
C7ꢀO9ꢀC10
O9ꢀC10ꢀC11
C17ꢀC12ꢀC13
GC MS(70 eV, m/z): 258 [M+], 256, 254, 230(30),
229(14), 228(25), 227(20), 149(37), 147(30), 145(22),
133(8), 131(15), 130(12), 128(10), 105(17), 103(22),
102(18), 99(8), 91(11), 89(10), 87(7), 82(17), 75(9),
73(11), 71 (8), 60(12), 43(16), 42(46), 41(100), 39(38),
30(32).
3.2.5. 3-Methyl-4-triethylgermyl-5-phenylisoxazoline-2
(9a)
and R-factor are 0.953 and 0.0565, respectively. The
program SHELXL-93 [23] were used for calculations.
The final coordinates and thermal parameters for non-
hydrogen atoms are listed in Table 4.
The pure product was isolated by column chro-
matography on silica gel with 1:1 hexane:ethyl acetate
as eluent.
1H-NMR (90 MHz, CDCl3/TMS) l (ppm): 0.72–
1.28 (15H, m), 1.96(3H, t, J=1.8 Hz), 2.73(1H, dd,
J=1.8, 5 Hz), 5.44(1H, d, J=5 Hz), 7.20–7.31(5H,
m).
3.2. General methods of preparation
3.2.1. Method A
GC MS(70 eV, m/z):321([M+]), 320, 319, 318,
292(19), 291, 290, 288, 278, 278, 277, 276, 266, 265, 264,
263, 262, 237, 236, 235(20), 234(16), 233(17), 161(28),
160(11), 159(18), 133(83), 132(66), 131(58), 105(80),
103(82), 101(47), 91(28), 77(57), 44(100). 3-Ethyl-4-tri-
ethylgermyl-5-phenylisoxazoline-2 (9b).
The pure product was isolated by column chro-
matography on silica gel with 1:1 hexane:ethyl acetate
as eluent.
Nitroethane (0.02 mol) and triethylamine (two drops)
in dry benzene (40 ml) were added dropwise during 4 h
to the mixture of germyl(silyl)substituted ethylene (0.02
mol), phenylisocyanate (0.04 mol) and triethylamine (1
ml) in dry benzene at room temperature. After some
minutes CO2 begins to release and diphenylurea precip-
itates. The mixture is heated for 4 h at 70–80°C. After
cooling to room temperature diphenylurea is filtered,
the solvent removed using the rotating evaporator.

160
E. Luke6ics et al. / Journal of Organometallic Chemistry 558 (1998) 155–161
1H-NMR (90 MHz, CDCl3/TMS) l (ppm): 0.84–
ether/pentane (10:1)). Anal. found: C, 65.91; H, 5.79;
N, 2.88. C26H27GeNO3 calc.: C, 65.87; H, 5.74; N,
2.95%.
01.26 (18H, m), 2.31 (2H, q, J=8 Hz), 2.78 (1H, d,
J=5 Hz), 5.44 (1H, d, J=5 Hz), 7.26–7.34 (5H, m).
GC MS (70 eV, m/z): 355 (18[M+]), 354 (16),
353(11), 307, 306(20), 305(17), 303(11), 235(20),
234(18), 232(12), 160(37), 159(35), 158(49), 135(18),
133(92), 131(82), 130(63), 105(96), 103(100), 101(52),
91(39), 77(61).
3.3. Method B
Benzhydroxamic acid chloride (0.02 mol) in dry ether
(20 ml) was added dropwise for 2 h to the mixture of
germylsubstituted ethylene (0.02 mol) and triethylamine
(0.02 mol) in dry ether (30 ml) at room temperature.
After some minutes triethylamine hydrochloride precip-
itated. The mixture was refluxed for 2 h. Triethylamine
hydrochloride was filtered off, the solvent removed
using the rotating evaporator.
3.2.6. (3-Methyl-4-triethylgermylisoxazolinyl-2)-5-
carboxylic acid ethyl ester (10a)
The pure product was isolated by column chro-
matography on silica gel with 5:1 hexane:ethyl acetate
as eluent.
1H-NMR (90 MHz, CDCl3/TMS) l (ppm): 0.89–
1.15 (15H, m), 1.31 (3H, t, J=6.9 Hz), 2.0 (3H, d,
J=1.2 Hz), 3.04 (1H, dd, J=1.2, 15.1 Hz), 4.27 (2H,
q, J=6.9 Hz), 4.57 (1H, d, J=15.1 Hz).
3.3.1. 3-Phenyl-5-triethylsilylisoxazoline-2 (2)
The pure product was isolated by column chromo-
tography on silica gel with 5:1 hexane:ethyl acetate as
eluent.
GC MS(70 eV, m/z):288([M-29]), 287, 284, 281, 262,
260, 259, 258, 255, 248(10), 247(45), 246(31), 243(22),
163, 161(41), 160(37), 159(21), 134(22), 133(100),
132(78), 130(58), 104(54), 103(58), 101(46), 90(14),
89(15), 77(11), 75(18), 74(9), 70(16), 44(83), 29(22).
1H-NMR (360.1 MHz,CDCl3/TMS) l (ppm): 0.6
(6H, dq, J=2.83, 7.41 Hz), 0.92 (9H, t, J=7.41 Hz),
3.03 (1H, dd, J=15.7, 15.92 Hz), 3.34 (1H, dd, J=
11.34, 15.7 Hz), 4.05 (1H, dd, J=11.34, 15.92 Hz),
7.27-7.29 (3H, m), 7.58–7.61 (2H, m).
3.2.7. (3-Ethyl-4-triethylgermyl-isoxazolinyl-2)-5-
carboxylic acid ethyl ester (10b)
3.3.2. 3-Phenyl-5-triethylgermylisoxazoline-2 (4),
m.p.=7–10°C ( from petroleum ether)
The pure product was isolated by column chro-
matography on silica gel with 5:1 hexane:ethyl acetate
as eluent.
1H-NMR (360.1 MHz, CDCl3/TMS) l (ppm): 0.951
(15H, m); 3.16 (1H, dd, J=15.25, 15.84 Hz); 3.51 (1H,
dd, J=10.86, 15.25 Hz); 4.37 (1H, dd, J=10.86, 15.84
Hz); 7.31–7.79 (5H, m).
1H-NMR (90 MHz, CDCl3/TMS) l (ppm): 0.91–
1.12 (18H, m), 1.14(3H, t, J=7.6 Hz), 2.21 (2H, q,
J=7.1 Hz), 3.08 (1H, dd, J=1, 14.8 Hz), 4.25 (2H, q,
J=7.6 Hz), 4.51 (1H, d, J=14.8 Hz).
3.3.3. 3-Phenyl-5-triethylgermylmethylisoxazoline-2 (6),
m.p.=20–22°C ( from petroleum ether)
GC MS(70 eV, m/z): 302 [M-29], 301, 298, 262(10),
261(18),
260(15),
243(10),
175(52),
174(41),
1H-NMR (360.1 MHz, CDCl3/TMS) l (ppm): 0.84
(6H, q, J=8.29 Hz); 1.06 (9H, t, J=8.29 Hz); 1.20
(1H, dd, J=6.54, 13.3 Hz); 1.40 (1H, dd, J=6.54, 13.3
Hz); 2.88 (1H, dd, J=9.15, 16.35 Hz); 3.38 (1H, dd,
J=9.81, 16.35 Hz); 4.90 (1H, m); 7.40 (3H, m); 7.65
(2H, m).
173(20),133(100), 132(70), 130(41), 105(78), 103(51),
101 (41), 90(14), 89(15), 68(81), 29(28).
3.2.8. (3-Methyl-4-triphenylgermyl-isoxazolinyl-2)-5-
carboxylic acid ethyl ester (11a)
1H-NMR (360.1 MHz,CDCl3/TMS)
l
(ppm):
1.11(3H, t, J=7.2 Hz), 1.92 (3H,d, J=1.08 Hz), 3.95–
4.04 (2H, m), 4.08 (1H, dq, J=1.08, 2.04, 11.99 Hz),
5.27 (1H, d, J=13.3 Hz), 7.37–7.42 (9H, m), 7.54–7.57
(6H, m). M.p.=116°C (from petroleum ether). Anal.
found: C, 65.18; H, 5.48; N, 3.00. C25H25GeNO3 calc.:
C, 65.27; H, 5.48; N, 3.04%.
3.3.4. 4-Triethylgermyl-3,5-diphenylisoxazoline-2 (9c)
The pure product was isolated by column chro-
matography on silica gel with 1:1 hexane:ethyl acetate
as eluent.
1H-NMR (90 MHz, CDCl3/TMS) l (ppm): 0.76–
1.15 (15H, m), 3.93 (1H, d, J=3.2 Hz), 5.73 (1H, d,
J=3.2 Hz), 7.28–7.41 (5H, m), 7.51–7.73 (5H, m).
3.2.9. (3-Ethyl-4-triphenylgermyl-isoxazolinyl-2)-5-
carboxylic acid ethyl ester (11b)
1H-NMR (360.1 MHz,CDCl3/TMS) l (ppm): 1.03
(3H, t, J=7.41 Hz), 1.12 (3H, t, J=7.19 Hz), 2.17
(1H, dq, J=1.08, 7.19 Hz), 2.38 (1H, dq, J=0.89, 7.41
Hz), 4.01 (2H, qua, J=7.19 Hz), 4.12 (1H, dt, J=1.08,
12.86 Hz), 5.28 (1H, d, J=12.86 Hz), 7.37–7.44 (10H,
m), 7.54–7.56 (6H, m). M.p.=114°C (from petroleum
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