Stereoselective synthesis of new hetero(P, Si, Ge, Sn)cyclic derivatives from zirconium diyne and diene complexes

Article abstract of DOI:10.1016/S0022-328X(98)00700-1

The dipropargylic derivatives of Si, Ge, P, 1a-c, react with the zirconocene entity 'Cp₂Zr' and give the intermediate bicyclocomplexes 2a-c characterized by ¹H and ³¹P-NMR. The electrophilic addition of H⁺, Br₂ leads to the corresponding exo dienic metallacyclopentanes 3,4. The cyclozirconation reaction with hetero-diallylic compounds 5a-d gives the metallacyclopentanes 7-15, after reaction with different electrophiles such as H⁺, PCl₃, PhPCl₂, Ph₂PCl or Ph₂PCl(BH₃), Br₂. The cyclozirconation reaction of diynes is stereoselective and leads to the E,E-exocyclic dienes whereas the selectivity of cyclozirconation of dienes depends on the substituents on the heteroatom.

Full text of DOI:10.1016/S0022-328X(98)00700-1

Journal of Organometallic Chemistry 564 (1998) 61–70
Stereoselective synthesis of new hetero(P, Si, Ge, Sn)cyclic derivatives
from zirconium diyne and diene complexes
Maryam Mirza-Aghayan, Rabah Boukherroub, Gabriel Oba, Georges Manuel, Max Koenig *
Laboratoire d’He´te´rochimie Fondamentale et Applique´e-UPRESA CNRS no 5069-Uni6ersite´ Paul-Sabatier, 31062 Toulouse Cedex, France
Received 23 January 1998; received in revised form 12 May 1998
Abstract
The dipropargylic derivatives of Si, Ge, P, 1a–c, react with the zirconocene entity ‘Cp2Zr’ and give the intermediate
1
bicyclocomplexes 2a–c characterized by H and 31P-NMR. The electrophilic addition of H+, Br2 leads to the corresponding exo
dienic metallacyclopentanes 3,4. The cyclozirconation reaction with hetero-diallylic compounds 5a–d gives the metallacyclopen-
tanes 7–15, after reaction with different electrophiles such as H+, PCl3, PhPCl2, Ph2PCl or Ph2PCl(BH3), Br2. The cyclozircona-
tion reaction of diynes is stereoselective and leads to the E,E-exocyclic dienes whereas the selectivity of cyclozirconation of dienes
depends on the substituents on the heteroatom. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Zirconocene; Zirconacomplexes; Cyclozirconation; Hetero(Si, Ge, P)cyclopentanes; Bis methylene hetero(Si, Ge,
P)cyclopentanes; Phosphines; Diphosphines; Selectivity
1. Introduction
mouth [11]. We will consider the simplified Scheme 2 in
which the reactive species ‘Cp2Zr’ is generated by alky-
lation of Cp2ZrCl2 with n-butyllithium, followed by the
elimination of 1-butene. Both | and y bonded struc-
tures are intermediates in this process [12].
In this paper, we will present our results [13] concern-
ing reactions of the in situ generated ‘Cp2Zr’ species
with dipropargylic 1a–d and diallylic 5a–d derivatives
of silicon, germanium, tin and phosphorus. We will
This study is a part of a larger project developed in
our laboratory related to the synthesis and the use of
heterocyclic molecules to prepare new compounds such
as organometallic polymers, precursors to drugs, chiral
molecules and y metalled species [1].
Examination of the literature shows that several se-
ries of transition metal complexes such as metallocenes
permit the synthesis of cyclic derivatives from polyun-
saturated heterocycles. The cyclozirconation reaction,
discovered independently by Nugent [2] and Negishi [3],
is one of the most powerful carbometallation [4] meth-
ods Scheme 1).
Heterodiynes and dienes containing oxygen [5],
boron [6], nitrogen ([3]b) [7] and silicon [8] have been
reacted with zirconium dicyclopentadienyl dichloride in
the presence of n-butyllithium. Such reactions have
been studied by Buchwald [9], Negishi [10] and Way-
* Corresponding author. Tel.: +33 05 61556298; fax: +33 05
61558245; e-mail: koenig@iris.ups-tlse.fr
Scheme 1.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00700-1

62
M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
nium–carbon bonds and to generate corresponding
heterocyclopentanes (Scheme 5).
In the case of diphenyl dipropargyl silane 1a%, meth-
ods A and B give 1,1-diphenyl 3,4-bis-methylene 1-sila-
cyclopentane 3a% in low yield by treatment of complex
2a% with diluted hydrochloric acid. Compound 3a% has
been previously prepared by C. Laurent [16] using a
different method.
Scheme 2.
discuss the reactivity of these intermediates with differ-
ent electrophiles and we will present the stereochemical
properties of the hetero (Si, Ge, P) cyclopentanes.
For bis h,ꢀ-(trimethylsilyl) dipropargylsilane com-
pound 1a, prepared according to method B, the cy-
clozirconation followed by protonation gives the
silacyclopentane 3a in a 72% yield. For 1b, (M=Ge)
and 1c (M=P), yields are lower than 50%. The later
result is probably the consequence of the presence of
the bulky group required to prevent phosphorus oxida-
tion and zirconium–phosphorus interaction [17]. In the
case of 1d (M=Sn), the cyclozirconation reaction was
unsuccessful.
The selective cyclozirconation of 1a leads to 3a iso-
mer in the s-cis (EE) exocyclic configuration. The s-
trans isomer is quantitatively obtained by heating
whereas the photochemical irradiation (300 nm in ben-
zene) gives first the corresponding s-cis (E,Z) and then
the s-cis (Z,Z) isomer ([13]a).
2. Results and discussion
2.1. Heterodiynes cyclozirconation
Heterodiynes 1a–d were synthesized according to
literature methods from dichloro-derivatives of Si, Ge,
Sn, P and the corresponding propargyl Grignard
reagents. For unsubstituted propargylic derivatives as
1a% (R3=H), a competitive reaction leads, even at 0°C,
to a mixture of dipropargylic, allenic propargylic and
diallenic silicon derivatives. These propargylic/allenic
rearrangements become the major process with
dichlorotin derivatives.
With dichlorophosphines, the reaction of the unsub-
stituted propargylic Grignard leads to polymeric
materials.
To prevent such undesired reactions, we have pre-
pared trimethylsilyl substituted propargylic derivatives
(R3=SiMe3) of Si, Ge, Sn, P (Scheme 3). This has been
achieved by the propargylic substitution of 1a% accord-
ing to a two step reaction. Compound 1a was thus
obtained in an 84% yield.
At low temperature, bromine reacts as an electrophile
with zirconium-sila (and germa) complexes 2a–b. The
corresponding 3,4-bis(bromo-trimethylsilylmethylene)1-
sila (and germa) cyclopentanes 4a–b were isolated and
characterized (Scheme 6):
1
Comparison of H and 13C-NMR spectra of 3a and
4a–b is interesting from a stereochemical point of view.
In compounds 4a–b, the two bulky bromine atoms in
the endo position induce a noticeable and stable twist-
ing of the silacyclopentane ring. So, the two hydrogen
atoms of the methylene group in h to silicon are always
magnetically equivalent in 3a whereas they remain an
AB system in 4a–b in the temperature range (−80– +
90°C).
Alternatively, compounds 1a–d can be prepared
from propargylic alcohol as acetylenic starting material
[14]. The synthetic Scheme 4 summarizes the four step
reactions process. Note that, a bulky substituent is
necessary to prevent oxidation of the trivalent phospho-
rus atom in 1c [15].
The cyclozirconation reaction was achieved by two
methods: the first method A consists of adding an
hexane solution of n-butyllithium to the (diyne 1a–d,
dichlorozirconocene) solution at −78°C. The zircona
complexes 2a–d were directly characterized by NMR at
room temperature (r.t.) (Table 1). In the second method
B, n-butyllithium solution was added at −78°C to the
dichlorozirconocene. The heterodiyne 1a–d was then
added at low temperature. These complexes 2a–d were
treated by electrophiles in order to cleave the zirco-
2.2. Heterodienes cyclozirconation
Heterodienes 5a–d were prepared by known methods
and then reacted with dichlorozirconocene in the pres-
ence of n-butyllithium, according to methods A or B.
7-Hetero-3-zirconabicyclo[3.3.0] complexes 6a–b were
1
characterized in THF solution by H-NMR spectra (see
Table 1). Zirconacomplexes 6a–d were treated with
dilute hydrochloric acid and the heterocyclopentanes
7a–c were isolated and fully characterized (Scheme 7).
It appears that the cyclozirconation reaction is highly
dependent on the nature of the heteroatom M and its
substituents R1 and R2. The best results (82% yield)
were obtained with the Ph2Si group (7a1). In the case of
Me2Si (7a2), Ph2Ge (7b) and ArP (7c2) yields are lower
(60, 40 and 33%, respectively). For the other unsatu-
rated phosphorus derivatives 7c1 (R1=Ph, R2=O) and
Scheme 3.

M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
63
Scheme 4.
n-Bu2Sn groups(7d2), the cyclozirconation reaction does
not occur.
length, cyclozirconation is both a regio and stereoselec-
tive process if appropriate ligands on zirconium are
utilized. This reaction may produce heterocyclopen-
tanes having a well defined stereochemistry. For this
reason, we have examined the influence of the different
heteroatoms and their substituents on the stereochem-
istry of the heterocyclopentanes.
Zirconium complexes 6a–d were also treated with
chlorophosphines. With trichlorophosphine, the com-
plex 6a does not lead to the expected 3-phospha-7-silab-
icyclo[3.3.0]octane but rather to the mono 8a and
disubstituted dichlorophosphines 9a (Scheme 8).
With phenyldichlorophosphine, the reaction takes
place at r.t. (Scheme 9) and the bicyclo derivatives
10a–b were isolated and fully characterized.
For 6b, (M=Ge), the purification leads to the corre-
sponding phosphine oxide 10b% (l 31P=61.6). For M=
Sn, the very unstable adduct 10d1 was characterized
only by NMR (l 31P= −4) and mass spectra (m/z=
465 [MH]+).
The electrophilic reaction of diphenylchlorophos-
phine on complex 6a at 20°C leads to a mixture of the
mono phosphine 11a (l 31P −18.9), as the major
product and 12a (l 31P −19.9) as the minor one
(Scheme 10).The by-product Ph2P(O)OBu results from
the addition of the phosphine to the mediated zir-
conocene ring opening of THF.
2.3.1. Stereochemistry of metallacyclopentanes 7a1–7a2
In order to precisely determine the stereochemical
properties of 7a, we prepared the corresponding silacy-
clopentanes by catalytic hydrogenation of 3,4-dimethyl-
1-metallacyclopent-3-enes 16a (Scheme 13).
It appears that the catalytic hydrogenation method
gives a 70/30 (7a1), 76/24 (7a2) mixture of cis/trans
isomers whereas the cyclozirconation–protonation re-
action is stereoselective and shows the formation of the
trans isomer only. For the cis isomer 7a2, the two
methyl groups on the silicon atom are diastereotopic.
On the other hand in the trans isomer 7a2, the two
methyl groups are magnetically equivalent and give
1
only a single signal in either H and 13C-NMR.
Similarly, the borane complex [Ph2PCl, BH3] reacts
with 6a and gives the corresponding borane complexed
mono and diphosphines 13a and 14a in the same ratio
as the previous experiment (Scheme 11).
An alternative way to obtain diphosphines 14a in-
volves reaction of diphosphine 12a, (Scheme 12)
purified by chromatography on silica column, with
borane.
We observed the same type of magnetic properties
for the ipso carbons of the two phenyl groups bonded
to Si and Ge in the compounds 15a–b and 12a.
Based on similar NMR data for compounds 15a–b
and 12a, we conclude that the cyclozirconation is a
trans -stereoselective process and that the electrophilic
cleavage of the Zr–C bonds, by various electrophiles,
proceeds with retention of configuration.
2.3. Stereochemical properties of the hetero(Si, Ge,
P)cyclopentanes
2.3.2. Stereochemistry of phosphines 7c and 10a–b
A coupling constant between the ipso carbon bonded
to the phosphorus atom (1JCP=23 Hz) is observed in
the13C-NMR. Carbon atoms C6 and C7 (Scheme 14) in
Results reported in the literature ([2]b) [5]([7]d,g)
[18,19] indicate that the stereochemistry of the cyclozir-
conation depends on several parameters. Among these
are the relative position of the two C–C double bonds
in the starting diene and the nature of the substituents
on the zirconium atom. For carbon chains of suitable
h position with respect to P are not equivalent (1JC7P
=
1
39.3 Hz; JC6P=37.4 Hz). Carbon atoms C3 and C4 in
i position with respect to P are also magnetically
different.
A
coupling constant with Phosphorus
(2JC6P=4.3 Hz) is only observed for C3. For carbon

64
M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
Table 1
NMR parameters of zirconabicycle intermediates
Number of compounds
l
1H
l
31P
Solvent
Cp
H2CM
H–C
Ph
Me3Si
2a
2b
6.0
2.0(s)
2.2(s)
2.1(s)
1.5(m)
7.3–7.7(m)
7.2–7.6(m)
7.3–7.6(m)
7.1
7.2–7.7
7.3–7.6
7.1–7.7
7.2–7.7
0.1(s)
0.2(s)
0.1(s)
0.1(s)
CDCl3
C6D6
CDCl3
CDCl3
C6D6
CDCl3
C6D6
CDCl3
5.96(s)
5.95(s)
6.0–6.05
5.8–5.9
5.9–6.1
5.9
2c
6a1
−19.5(THF)
0.9–1.7
0.5–1.7
0.6–1.7
0.6–1.6
6b
5.96–5.99(d)
atoms C2 and C5 in h position with respect to Si, we
only observed the coupling between C5 and the phos-
phorus atom (3JC5–P=4.4 Hz).
of the stability of the starting material, compared to the
unsaturated analogs in the carbon series. For example,
the relative weakness of Sn–C bond may explain the
lack of cyclozirconation products in the tin series.
In Si and Ge series, the expected cycloadducts are
synthesized with higher yields than the P analogs.
Moreover, in the Phosphorus series, the cyclozircona-
tion failed in the case of the phosphine oxide. The
oxophilicity of Zirconium or the basicity of the phos-
phine probably prevents the metallacyclisation. A bulky
substituent in phosphine is required in order to decrease
its basicity and to allow the cyclozirconation of the
heterodiene and heterodiyne.
1
3
The H-NMR spectra indicates two different JHCP
coupling constants for the hydrogens bonded to C3 and
3
3
C4: JHC3P=30 Hz and JHC4P=0. The notable effects
3
observed for the JHP values are a consequence of the
relative orientation of the phosphorus lone pair to-
wards the plane of the ring atoms. The corresponding
coupling constants are enhanced when their respective
positions are syn to one another [20]. So, we may
deduce that the protons directly bonded to C3 and C4
are in a trans configuration.
The two methyl substituents on the phospholane 7c2
are equivalent (l=15.9) by 13C-NMR and have the
same coupling constant with the phosphorus atom
(3JCP=4.3 Hz). We may conclude that the two methyl
goups are cis and probably in a syn orientation to the
lone pair of phosphorus atoms (Scheme 15).
The difference in stereoselectivity of the zirconacycli-
sation is a consequence of the nature of the substituents
bonded to the heteroatom. When the substituents are
identical (R1=R2) the products are obtained in trans
configuration. This configuration induces an intrinsic
chirality to the phosphines 10 or to the diphosphines 12
and 14. When the substituents are different (R1=Ar,
R2=lone pair), the preferential configuration is cis and
the considered molecules as 7c2 are achiral.
Finally, the selectivity of such heterocyclisations is
closely dependent on the (a)symmetry induced by the
steric bulkiness of the heteroatom’s substituents. With
two identical substituents on the heteroatom (Si, Ge),
the resulting cyclopentanes are in trans configuration.
On the other hand, with two different substituents on
the heteroatom (P), the resulting phospholane is substi-
tuted in cis configuration.
4. Experimental section
4.1. General procedure
All manipulations, except chromatography on silica
gel, were carried under an argon atmosphere. THF,
diethyl ether and hexane were distilled from solutions
of sodium/benzophenone and stored under argon. All
NMR spectra were recorded at 25°C on Bruker AC 80
and 250 MHz in deuteriochloroform and deuterioben-
3. Conclusion
The heterocyclisation of dipropargyl and diallylic
derivatives of silicon, germanium, phosphorus and tin
have been carried out. Resulting zirconacomplexes have
been reacted with electrophiles as proton, bromine and
various chlorophosphines. It appears that the results
depend on the nature of the heteroatom and its
substituents.
1
zene. The H and 13C chemical shifts were referenced
relative to TMS while 31P-NMR shifts were referenced
to H3PO4 (85%). Coupling constants are given in Hertz.
Mass spectra were obtained on a Ribermag R1010
under electron impact (EI) or chemical ionization (DCI
conditions) with CH4 or NH3. Low-resolution mass
spectra were determined by GC/MS using Hewlett-
Packard 5890 serieII gas chromatograph equipped with
So, the decrease of the Heteroatom–Carbon bond
enthalpy (Si\Ge\P\Sn) induces a notable lowering

M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
65
Scheme 5.
a HP/MS 5989A mass selective detector. Melting points
C, 70.86; H, 8.42. Found: C, 70.77; H, 8.74%.
1
were determined in evacuated capillaries with a Buchi-
Tottoli apparatus. IR spectra were recorded on Perkin
Elmer 1600Series FTIR.
3a S-trans: H-NMR (CDCl3): l 0.03 (s, 9H, Me3Si),
0.21 (s, 9H, Me3Si), 2.09 (s, 2H, CH2SiMe3), 2.26
(d,4JHH=1.7Hz, 2H, CH2SiPh2), 5.88 (t,4JHH=1.5Hz,
1H, ꢀCHSiMe3), 6.06(s, 1H, ꢀCHSiMe3), 7.15–7.67 (m,
10H, Ph).
4.2. Compounds 3a–c
1
3b: H-NMR (CDCl3): l 0.18 (s, 18H, Me), 2.30 (d,
To a solution of dichlorozirconocene (1.16 g, 4
mmol) in 15 ml of THF at −78°C was added n-BuLi
1.6 M (5 ml, 8 mmol). The resulting mixture was stirred
for 1 h at −78°C. To this solution was added metal-
ladipropargyles 1a–d (3.21 mmol) in 5 ml THF at
−78°C. The solution was stirred for 2 h at r.t. The
reaction was quenched (0°C) with 10% HCl (25 ml),
extracted with ether (3×50 ml), washed with aqueous
sodium bicarbonate and water and dried over MgSO4.
Removal of solvent followed by chromatography on
silica gel and eluted with hexane/ether: 98/2 (Rf=0.71),
hexane/ether: 99/1 (Rf=0.71), hexane/ether: 95/5 (Rf=
0.81)] afforded 3a, 0.94 g as colorless liquid (72%), 3b,
0.65g as colorless liquid (45%) and 3c, 0.79g as yellow
oil (49%).
4JHH=1.75, 4H, CH2Ge), 5.91 (t, 4JHH=1.77, 2H,
ꢀCH), 7.34–7.49 (m, 10H, Ph). 13C-NMR (CDCl3):
‘J-mod’ l 0.16 (s, C6 H3Si), 21.09 (s, C6 H2Si), 123.45 (s,
ꢀCH), 128.34, 129.21 and 134.19 (CH arom.), 134.04
(Cipso), 162.82 (s, ꢁC=). MS: m/z 452 [M]+, 378
[M–Me3Si]+, 363 [M–Me3SiH–Me]+, 227 [Ph2Ge]+.
Anal. Calc. for C24H34Si2Ge: C, 63.87; H, 7.59. Found:
C, 62.98; H, 7.86%.
3c: 31P-NMR (CDCl3):
l
−11.13. 1H-NMR
(CDCl3): l 0.14 (s, 18H, Me3Si), 1.26, 1.32 and 1.53 (3s,
27H, CH3), 3.21–3.31 (m, 4H, CH2), 5.96 (d, 2H, CH),
7.12 (s, 2H, Ar). 13C-NMR (CDCl3): ‘J-mod’ l −0.33
(s, C
6
H3Si), 21.71 (s, CH3–C
6 (1%%%%)), 31.3 (s, C6 H3 (2%%%%),
33.33 and 33.58 (2s, C
(1%% and 1%%%)), 41.74 (d, JPC=14.0 Hz, CH2P (C2 and
C5)), 120.3 (d, JPC=4,3 Hz, ꢀCH (C6 and C7)), 122.47
6
H3 (2%% and 2%%%)), 39.0 (2s, CH3–C
6
1
1
3
3a%: H-NMR (CDCl3): l 2.21 (m, 4H, CH2Si), 4.71–
4.92 (m, 2H, CH2Si), 5.23–5.36 (m, 2H, ꢀCH2), 7.24–
(s, CH (C3% and C5%), 146.76 (s, Cipso 2%, 6% and 4%), 153.85
(d, JCP=20,2 Hz Cipso (1%), 154.25 (s, \Cꢀ(C3, C4)).
MS: m/z 501 [MH]+ (100%), 485 [MH-16]+, 429 [MH-
72]+.
7.61 (m, 10H, Ph). Ms: m/z 262 [M]+.
, 184
[MH–Ph]+., 105 (MH–Ph–C6H8]+.
3a S-cis:1H-NMR (CDCl3): l 0.13 (s, 18H, Me3Si),
4
4
2.18 (d, JHH=1.7 Hz, 4H, CH2Si), 5.96 (t, JHH=1.7
Hz, 2H, CH), 7.24–7.49 (m, 10H, Ph). 13C-NMR
(CDCl3) ‘J-mod’ l 0.24 (s, C6 H3 Si), 20.71 (s, C6 H2 Si),
122.71 (s, ꢀCH), 127.91, 129.81 and 134.83 (CH arom.),
134.70 (Cipso PhSi), 159.56 (s, ꢀCB). Ms: m/z 406
[M]+., 332 [M–H–Me3Si]+. Anal. Calc. for C24H34Si3:
Scheme 6.
Scheme 7.

66
M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
Scheme 8.
1H-NMR (CDCl3): l 0.28 (s, 18H, SiMe3), 2.09, 2.55
4.3. Compounds 4a–b
(AB system, 4H, JAB=12.5 Hz, CH2), 7.4–7.6 (m,
10H, Ph). 13C-NMR (CDCl3): ‘J-mod’ l 0.69 (s,
4.3.1. Compound 4a
To a solution of dichlorozirconocene (Cp2ZrCl2)
(0.72 g, 2.47 mmol) in 15 ml of THF at −78°C was
added n-BuLi 1.6 M (3 ml, 4.95 mmol). The resulting
mixture was stirred for 1 h at −78°C. To this solution
was added metalladipropargyle 1a (1 g, 2.47 mmol) in 5
ml THF at −78°C. The solution was stirred for 2 h at
r.t. The mixture was cooled to −78°C and a solution
of bromine (1.04 g, 5.8 mmol) in carbon tetrachloride
(8ml) was added. The reaction was quenched at r.t.
with 10% H2SO4 (50 ml), extracted with ether (3×50
ml), washed with aqueous sodium bicarbonate and
water, and dried (MgSO4). After filtration, the solvent
was removed by evaporation under reduced pressure.
The residue was purified by chromatography on silica
gel and eluted with hexane (Rf=0.06). A white powder
(0.50 g), m.p.=56–58°C was obtained in 35% yield.
1H-NMR (CDCl3): l 0.21 (s, 18H, SiMe3), 2.01, 2.39
(AB system, 4H, JAB=14.4 Hz, CH2), 7.39–7.47 (m,
10H, Ph). 13C-NMR (CDCl3): ‘J-mod’ l 0.59 (s,
C
6
H3Si), 22.32 (s, C
6 H2Ge), 120.1 (s, ꢀC6 –Br), 128.54,
129.69 and 134.1 (3 s, CH arom.), 135.69 (s, Cipso),
155.11 (s, ꢁC6
=). MS: DCI (CH4) m/z 608 [MH]+,
595 [MH–CH3]+. Anal. Calc. for C24H32Si2GeBr2: C,
47.32; H, 5.26. Found: C, 48.12; H, 5.44%.
4.4. Compounds 7a–c
4.4.1. Cyclozirconation
To a solution of dichlorozirconocene (Cp2ZrCl2)
(1.16 g, 4 mmol) in 15 ml of THF at −78°C was added
n-BuLi 1.6 M (5 ml, 8 mmol). The resulting mixture
was stirred for 1 h at −78°C. To this new solution was
added metalladienes 5a–d (4 mmol) in 5 ml THF at
−78°C. The solution was stirred for 2 h at r.t. The
reaction was quenched (0°C) with 10% HCl (50 ml),
extracted with ether (or CH2Cl2 for 5c2) (3×50 ml).The
organic layer was washed with aqueous potassium car-
bonate and aqueous sodium chloride and dried over
anhydrous sodium sulphate. Removal of solvent fol-
lowed by chromatography on silica gel eluted with
hexane (7a1); pentane/ether: 98/2 (Rf=0.8) (7a2); hex-
ane (7b); hexane/ether: 90/10 (7c2); afforded 7a1 0.88 g
of white solid (82%), 7a2 0.35 g of colorless liquid
(61%), 7b 0.50 g of colorless liquid (40%), and 7c2 0.48
g of yellow oil (33%).
C
6
H3Si), 22.05 (s, C
6 H2Si), 120.37 (s, ꢀC6 –Br), 128.17,
130.23 and 134.76 (3 s, CH arom.), 133.59 (s, Cipso),
153.90 (s, ꢁC6
ꢀ). MS: m/z 582 [MH+17]+, 565
[MH]+. Anal. Calc. for C24H32Si3Br2: C, 51.05; H,
5.71. Found: C, 51.11; H, 5.73%.
4.3.2. Compound 4b
7a1 Trans: m.p.=28–29°C. 1H-NMR (CDCl3): l
0.6–1.7 (m, 12H, CH2, CH and CH3), 7.3–7.7 (m, 10H,
Ph). 13C-NMR (CDCl3): ‘J-mod’ l 21.95 (s, CH3),
22.68 (s, SiCH2), 42.47 (s, CH), 127.88, 129.21 and
134.7 (CH arom.), 137.18 (Cipso). MS (m/z) 266 [M]+.
Anal. Calc. for C18H22Si: C, 81.44; H, 8.31. Found: C,
81.15; H, 8.46%. IR (CDCl3) w cm−1 3053 (CH arom),
2954 (CH2).
In the same conditions, 1.04g (2.35 equivalent) of
bromine in CCl4 (4 ml) was introduced at −78°C on
the intermediate 2b. We thus obtained, after purifica-
tion on the Chromatotron apparatus (hexane/CH2Cl2:
98/2) 0.78 g of white crystals (52% yield): m.p. 126–
127°C.
1
7a2 Trans: H-NMR (CDCl3): l 0.07 (s, 6H, CH3Si),
0.16–1.8 (m, 12H, CH2, CH, CH3). 13C-NMR (CDCl3):
‘J-mod’ l −1.10 (s, CH3Si), 21.9 (s, CH3), 23.7 (s,
SiCH2), 41.8 (s, CH).
Scheme 9.

M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
67
Scheme 10.
7b Trans: 1H-NMR (CDCl3): l 0.9–1.8 (m, 12H,
4.5. Compounds 10a–b%
4.5.1. Compounds 10a1
CH2, CH, CH3), 7.34–7.55 (m, 10H, Ph). 13C-NMR
(CDCl3): ‘J-mod’ l 21.89 (s, CH3), 23.26 (s, GeCH2),
42.82 (s, CH), 128.19, 128.71 and 134.29 (s, CH arom.),
139.06 (Cipso). MS (m/z) 312 [M]+. Anal. Calc. for
C18H22Ge: C, 69.52; H, 7.13. Found: C, 70.11; H,
7.28%. IR w 3049 cm−1 (CH arom.).
To a solution of 6a1 (one equivalent) in 15 ml of
THF, PhPCl2 (0.61 g, 3.41 mmol) was added at r.t. The
mixture was stirred for 30 min and the solvent was
removed in vacuo. The product was extracted from the
residue with hexane. The fractions containing product
were combined. Removal of solvent followed by chro-
matography (silica gel eluted with hexane/ether: 97/3)
afforded 10a1 as white powder (0.58 g, 46%). M.p.=
108–111°C. 31P-NMR (CDCl3): l −1.15.1H-NMR
(CDCl3): l 0.97 (m, 2H, CH2Si), 1.61–1.87 (m, 4 H,
CH2Si and CH2P), 2.12 (m, 2 H, CH2P), 2.33 (dd, 1H,
7c2 Cis: 31P-NMR (CDCl3):
d
7.65. 1H-NMR
(CDCl3): l 0.7–1.8 (m, 39H, CH2, CH, CH3 and tBu),
7.1 (2s, 2H, Ar). 13C-NMR (CDCl3): ‘J-mod’ l 15.93
(d, 3JCP=4.3 Hz, CH3CH), 30.49 (s, C
6
–CH3 (p)),
31.38, 33.54 and 33.96(3s, CH3 (p and o)), 38.87 (s, C3
and C4), 39.37 (s, C
–CH3 (o)), 41.91 (d, 1JCP=13.6 Hz,
6
PCH2), 121.55 (s, CH, Ar), 145.83 (Cipso Ar (p)), 149.90
(Cipso Ar (o)), 153.95 (d, 1JCP=3.45 Hz, C–P). MS
(m/z) 360 [M–H]+, 317 [M–H–C3H6]+. IR w 3049
cm−1 (CH arom.).
3
CH), 2.59–2.77 (m, 1H, CH, JPH=30 Hz), 7.34–7.68
(m, 15H, Ph). 13C-NMR (CDCl3): ‘J-mod’ l 18.28 (s,
SiCH2), 18.63 (d, SiCH2, 3JPC=4.4 Hz), 33.47 (d,
1
1
PCH2(C6), JCP=37.4 Hz), 33.67 (d, PCH2(C7), JCP
=
4.4.2. (b) Hydrogenation
2
39.3 Hz), 51.47 (d, CH(C3), JCP=4.2 Hz), 52.45 (s,
7a1 Cis/trans: A solution of silacyclopentene 16a1 (2
g, 7.57 mmol) in 60 ml of hexane and 200 mg (1.42
mmol) of palladium on carbon 10% in a autoclave filled
with hydrogen at a pressure of 100 bar was maintained
at 100°C. After 1 h, the mixture was filtered. Distilla-
tion afforded 0.70 g of 7a1 (cis/trans:70/30) in 35%
yield.
CH(C4)), 127.41 (s, Cp (PhP)), 128.49 (d, Cm (PhP),
3JCP=5.0 Hz), 130.32 (d, JCP=15.8 Hz, Co (PhP)),
2
128.16, 128.33, 129.63, 134.67 and 134.70 (CH arom.),
1
136.61 (Cipso), 136.81(Cipso), 143.35 (d, JCP=23.1, Cipso
of PhP). MS (m/z) 372 [M]+. Anal. Calc. for C24H25
SiP: C, 77.38; H, 6.76. Found: C, 74.06; H, 6.59%.
1H-NMR (CDCl3): l 0.70–2.21 (m, 12H, CH2, CH,
CH3), 7.3–7.8 (m, 10H, Ph). 13C-NMR (C6D6) ‘J mod’
l 19.38 (s, CH3 (cis)), 22.03 (s, CH3 (trans)), 22.75 (s,
SiCH2 (trans)), 23.85 (s, SiCH2 (cis)), 38.90 (s, CH
(cis)), 42.55 (s, CH (trans)), 130.82 and 136.48 (2s, Cipso
(cis)), 137.23 (s, Cipso (trans)), 127.96, 127.98, 129.28,
129.48, 134.71 and 134.84 (CH arom. (cis and trans)).
7a2 Cis/trans: A solution of silacyclopentene 16a2 (2
g, 14 mmol) in 60 ml of hexane and 152 mg (1.42
mmol) of palladium on carbon 10% in a autoclave filled
with hydrogen at a pressure of 100 bar, was maintained
at 100°C. After 1 h, the mixture was filtered. Distilla-
tion of the solution afforded 0.81 g of 7a2 (cis/trans:76/
24) in 41% yield.
4.6. Compound 10b%
To a solution of 6b (one equivalent) in 15 ml of
THF, PhPCl2 (0.53 g, 2.96 mmol) was added at r.t. The
mixture was stirred for 6 h and solvent was removed in
vacuo. The product was extracted from the residue with
hexane. The fractions containing the product were com-
bined. Removal of solvent followed by chromatography
(silica gel eluted with chloroform/dichloromethane 1/1)
afforded 10b’ as white powder (0.58 g, 45%). M.p.=
178–180°C. 31P-NMR (CDCl3): l 61.64. 1H-NMR
(CDCl3): d 0.98–2.4 (m, 8H, GeCH2, PCH2), 2.5–2.6
(m, 2H, CH), 7.5–7.7 (m, 15H, Ph). 13C-NMR
(CDCl3): ‘J-mod’ l 19.8 (d, GeCH2, 3JCP=9.9 Hz),
20.11 (d, GeCH2, 3JCP=9.37 Hz), 37.90 (d, PCH2,
Retention time(s): 210 (trans); 243 (cis). 1H-NMR
(CDCl3): l 0.06 (s, 3 H, CH3Si (cis)), 0.07 (s, 6H,
CH3Si (trans)), 0.15 (s, 3H, CH3Si (cis)), 0.16–2.10 (m,
12H, CH2Si, CH, CH3). 13C-NMR (C6D6) ‘J-mod’ l
−1.10 (s, CH3Si (trans)), −0.87 (s,CH3 (cis)), 0.19 (s,
CH3Si (cis)), 17.69 (s, CH3 (cis)), 21.02 (s,CH2Si (cis)),
22.48 (s, CH3 (trans)), 23.76 (s, CH2Si (trans)), 38.36 (s,
CH (cis)), 41.91 (s, CH (trans)).
1JCP=40.8 Hz), 38.9 (d, PCH2, JCP=39.7 Hz), 48.43
1
(d, CHC3, 2JCP=6.1 Hz), 49.6 (d, CHC4, 2JCP=6.2
Hz), 128.4–134.6 (CH arom.), 135.5 (s, Cipso PhGe),
139.51 (d, Cipso PPh, 1JCP=6.9 Hz). MS (m/z) 435
(MH)+, 357 (M–Ph)+. IR (CDCl3) w cm−1 3068 (CH),
2962 (CH2), 1212 (PꢀO).

68
M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
Scheme 11.
4.8. Compounds 13a–14a
4.8.1. Compound 13a
4.7. Compounds 11a–12a
4.7.1. Compound 11a
To a solution of Ph2PCl (1.50 g, 6.8 mmol) in 3 ml of
THF [BH3, SMe2] (3.4 ml, 6.8 mmol, 2 M in toluene)
was added at 25°C. The mixture was stirred for 15 h.
The resulting solution was added to 6a at r.t. After 2 h
the solvent was removed in vacuo. The product was
extracted from the residue with hexane. The fractions
containing the product were combined. Removal of
solvent followed by chromatography (silica gel eluted
with hexane/dichloromethane 1/1) afforded 1.26 g of
13a as colorless liquid (40%). 31P-NMR (C6D6): l
To a solution of 6a (one equivalent) in 15 ml of
THF, Ph2PCl (1.47 g, 6.68 mmol) was added at r.t. The
mixture was stirred for 9 h and solvent was removed in
vacuo. The product was extracted from the residue with
hexane. The fractions containing product were com-
bined. Removal of solvent followed by chromatography
(silica gel eluted with hexane/ether 98/2) afforded 11a
as white crystals (0.90 g, 30%). 31P-NMR (CDCl3): l
1
−18.6. H-NMR (CDCl3): l 0.9 (m, 2H, CH2 Si), 1.1
3
(d, JHH=7.5 Hz, 3H, CH3), 1.2–2.1 (m, 5H, CH2Si,
1
14.16. H-NMR (C6D6): l 0.82–2.40 (m, 11H, CH2 Si,
CH2 P, CH6 –CH3), 3.6 (m, 1H, CH6 –CH2P), 7.4–7.8
BH3, CH and CH2P), 0.99 (d, 3JHH=7.5 Hz, 3H, CH3),
7.11–7.71 (m, 20H, H arom.). MS (m/z) 482 [MH+
NH3]+(100%), 451 [MH–BH3]+. IR (CHCl3) w cm−1
2956 (CH), 2870 (CH2), 759 (Ph–Si).
(m, 20H, Ph). 13C-NMR (CDCl3): ‘J-mod’ l 20.51 (d,
3
SiCH2, JCP=8.6 Hz), 21.74 (s, CH3), 22.13 (s, SiCH2),
35.97 (d, PCH2, 1JCP=11.6 Hz), 42.36 (d, CH
6
CH3,
3JCP=8.8 Hz), 44.9 (d, CH
6
CH2P, 2JCP=12.6 Hz),
127.85–134.75 (CH arom.), 136.70 and 136.75 (2s, Cipso
4.8.2. Compound 14a
1
PhSi), 138.48 (d, Cipso PPh, JCP=13.2 Hz), 140.4 (d,
To a solution of diphosphine 12a (0.1 g, 0.16 mmol)
in 4 ml of THF [BH3, SMe2] (0.16 ml, 0.32 mmol, 2 M
in toluene) was added at 25°C. After 15 h we observed
the formation of a precipitate. The supernatant was
separated, concentrated and purified by preparative
thin layer chromatography (hexane/ether 60/40).This
afforded afforded 0.07 g of 14a as white crystals (67%).
1
Cipso PPh, JCP=13.4 Hz). MS (m/z) 451 [MH]+.
4.7.2. Compound 12a
A sample of Ph2PLi was prepared from 0.37 g of
Ph3P (two equivalents, 1.41 mmol) in 8 ml of degazed
THF and 0.11 g of lithium (20 equivalents, 15.7 mmol)
at r.t. To this solution, after removal of lithium, was
added 0.17 ml of tBuCl (two equivalents, 1.56 mmol).
To a solution of Ph2PLi (1.41 mmol, two equivalents)
in 8 ml of THF, was added dibromo silacyclopentane
15a (0.32 g, 0.75 mmol) in 4 ml of THF at −78°C. The
mixture was stirred for 15 h and the precipitate was
removed. Removal of solvent followed by chromatog-
raphy (silica gel eluted with pentane/ether 98/2) af-
forded 12a as white powder (0.30 g, 62%). M.p.
118–120°C. 31P-NMR (CDCl3): l −19.2. 1H-NMR
(CDCl3): l 1.02–1.36 (m, 4H, CH2 Si), 1.78–1.90 (m,
4H, CH2 P), 2.57–2.61 (m, 2H, CH), 7.05–7.52 (m,
30H, Ph). 13C-NMR (C6D6): ‘J-mod’ l 20.33 (d, SiCH2,
1
31P-NMR (C6D6): l 14.23. H-NMR (C6D6): l 0.50–
2.66 (m, 16H, CH2Si, CH, CH2P and BH3), 6.94–7.73
(m, 30H, Ph). 13C-NMR (C6D6): ‘J-mod’ l 21.68 (s,
1
CH2Si), 32,52 (d, CH2P, JCP=35 Hz), 43.27 (d, CH,
2JCP=12 Hz), 129.04–135.07 (CH arom.), 132.13 (s,
Cipso PhSi), 132.6 (s, Cipso PhP), 135.9 (s, Cipso PhP).
11B-NMR (C6D6): l −38.6. MS (m/z) 680 [MH+
NH3]+ (100%), 649 [MH–BH3]+. IR (C6D6) w cm−1
3050 (CH), 2923 (CH2), 1108 (Ph–Si). Anal. Calc. for
C42H46B2P2Si: C, 76.15; H, 7.00. Found: C, 74.04; H,
7.20%.
4.9. Compounds 15a–b
1
3JCP=9.7 Hz), 36.36 (d, PCH2, JCP=12.6 Hz), 44.02
To a solution of 6a–b (3 mmol) in 15 ml of THF, a
solution of bromine (2.35 equivalents) was added in
carbon tetrachloride (10 ml) at −78°C. The reaction
was quenched (r.t.) with 10% H2SO4 (50 ml), extracted
with ether (3×50 ml), washed with aqueous sodium
bicarbonate and water, and dried on anhydrous
MgSO4. Removal of solvent followed by chromatogra-
2
3
(dd, JCP=12.4 Hz, JCP=8.4 Hz, CH), 129.03–135.11
1
(CH arom.), 136.9 (s, Cipso PhSi), 139.4 (d, JCP=14.1
1
Hz, Cipso PhP), 140.9 (d, JCP=13.08 Hz, Cipso PhP).
MS (m/z) 635 [MH]+. Anal. Calc. for C42 H40 Si P2: C,
79.48; H, 6.34. Found: C, 78.34; H, 6.38%. IR w cm−1
3063 (CH), 2922 (CH2), 1110 (PhSi).

M. Mirza-Aghayan et al. / Journal of Organometallic Chemistry 564 (1998) 61–70
69
Scheme 12.
Acknowledgements
The authors are grateful to Professor W.P. Weber,
Loker Hydrocarbon Institute, University of Southern
California, Los Angeles, USA, for very helpful
discussions.
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1
15a: M.p. 73–75°C. H-NMR (CDCl3): l 1.43–1.53
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