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Anionic O C Rearrangements in Trialkylsiloxy-benzenes and Trialkylsiloxypyridines.

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[labs. 2 3 &&s.)].
The positions of the Co atoms were determined by a Patterson synthesis, and those of all the other
atoms by difference Fourier synthesis. Refinement of the
atomic coordinates and anisotropic temperature factor coefficients for the Co, 0, N. and C atoms converged at R=0.073.
The structure found for (I) (Fig. 1) does not possess a
plane of symmetry; the molecules adopt a chiral conformation.
The centrosyrnmetric unit cell contains four (two sets of two
enantiomorphic) molecules. The tertiary H atom in the center
of the bridge (on C 10) is directed towards the planar ligand
system. In this system, which includes the four nitrogen atoms
(N1 to N4), the four oxygen atoms, and the eight C atoms
(C1 to C4; C16 to C19) the individual atomic nuclei deviate
by no more than 0.12 8, from the regression plane. The temperature factor coefficients determined indicate that the bridging
C atoms (C3 to C17) are ordered in the crystal lattice and
that the bridge is comparatively rigid. This contrasts with
the structure of the bridged but not intramolecularly alkylated
cobaloxime[6].
Received: March 18, 1976 [Z 442 IE]
German version: Angew. Chem. 88. 443 (1976)
Table 1. Trialkylsilylphenols (2) from (1). R3Si occupies the position of
X. Me=CH3, Et=C2H5.
a
b
c
d
e
f
g
X
R
R'
RZ
Conditions
t
T~C:
2-Br
2-Br
2-Br
3-Br
4-Br
4-Br
4-Br
Me
Et
Me
Me
Me
Me
Et
H
H
H
H
H
Me
Me
H
H
-30
-30
-30
-30
25
25
25
Me
H
30min
15min
20min
3h
24h
12h
14h
Yield
B.p. rC/torr]
m.p.
76
97
93
80
85
80
76
85/12
120/0.05
116/12
114/12
74
45/0.01
[%I
rc]
115/0.03
Crossover experiments revealed an intermolecular reaction
course for 4-bromotrialkylphenoxysilanes such as (I e) and
(I g), but an intramolecular mechanism in the case of 2-bromotrialkylphenoxysilanes such as ( 1 b) and (I c ) . Thus a mixture
of (I e) and ( l g ) gave 19.2 % of (2e) and 18.3 % of (29)
together with 25.6 % of the crossover products 4-triethylsilylphenol and 18 % of (2f). A mixture of ( I b) and (I c) led
to 49.5 % of (2b) and 45.8 % of ( 2 c ) . (Yields determined
by gas chromatography.)
CAS Registry numbers:
( l ) , 58958-38-6; (2), 58944-42-6; ( 3 ) , 58944-43-7; ( 4 ) , 58944-44-8; ( S ) ,
58944-45-9; (6), 58944-46-0; (7). 58944-47-1; (8), 58944-48-2; (91, 58944-493; ( l o ) , 58944-50-6; ( I I ) , 58944-51-7
[l] J . Rltey, Helv. Chim. Acta 54, 2747 (1971).
[2] G . Bidhgmaier, H. Flohr, U . M . Kempe, 7: Krebs, and J . Rdtey, Angew.
Chem. 87, 877 (1975); Angew. Chem. Int. Ed. Engl. 14, 822 (1975).
[3] J. Schreiber, D. Felix, A . Eschenmoser, M . Winter, F . Gautschi, K . H .
Schulte-Eke, E. Sundt, G . Ohloff, J . Kaluoda, H. Kaufmann, P . Wieland,
and G . Anner, Helv. Chim. Acta 50, 2101 (1967). We are grateful to
Prof. A . Eschenmoser and Dr. D. Felix for communication of the procedure
prior to its publication.
[4] L. Rd, B. Maurer, and G. Ohloff, Helv. Chim. Acta 56, 1882 (1973).
[5] Wearegrateful to 7: Keller, T/: FormaEek, and Dr. W E. Hul/ (Bruker-Physik, Karlsruhe) for recording the 'H-NMR spectrum on a WH 270
MHz spectrometer.
[6] M. Bartiett u. I . D. Dunitz, Helv. Chim. Acta 54, 2753 (1971).
In the aliphatic series 1,2-anionic rearrangements with trialkylsilyl shifts are known for benzyl trialkylsilyl ethersC21,and
1,3-anionic rearrangements for hexamethyldisiIo~ane[~].
Mercuric iodide catalyzes the rearrangement of O-alkyl-O-trimethylsilylketene acetals to a-trimethylsilyl carboxylic esters[4'.
While rearrangement experiments with naphthalene derivatives were not very transparent, the reaction can be extended
without difficulty to 3-, 5-, and 6-bromo-2-trimethylsiloxypyridines (5) (Table 2).
R2
R2
Anionic 0 C Rearrangements in Trialkylsiloxybenzenes and Trialkylsiloxypyridines'']
--f
By Gerhard Simchen and Jorg PfletschingerC*]
During studies of C-trialkylsilylation reactions['] we' have
found that, after prior metalation with tert-butyllithium in
tetrahydrofuran, bromine-substituted trialkylphenoxysilanes
(I ) rearrange under very mild conditions to trialkylsilylphenols (2) (Table 1). After the rearrangement the trialkylsilyl
group occupies the position of the halogen.
k
(6)
Table 2. Trimethylsilyl-2-pyridones (6) from ( 5 ) . (CH3)aSi occupies the
position of X. Me=CH3, Ph=C6H5.
X
a
b
c
d
e
The reaction proceeds via trialkylsiloxy carbanions ( 3 )
which are in equilibrium with trialkylsilylphenoxide ions (4 ).
The equilibrium shifts in favor of the C-silylation products
(4) with falling temperature.
[*] Prof. Dr. G. Simchen and Dr. J. Pfletschinger
Institut f i r Organische Chemie, Biochemie und lsotopenforschung der
Universitat
Pfaffenwaldring 55, 7000 Stnttgart 80 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Indnstrie.
428
3-Br
5-Br
5-Br
5-Br
6-Br
R'
H
Me
H
H
R2
H
H
H
H
Ph
R'
H
H
H
Me
Conditions
TrC]
f
25
25
25
25
25
24
18
20
42
22
[h]
Yield
[%]
M.p
["C]
62
51
98
47
69
101-102
91-93
151-153
191-194
210-212
General procedure:
tert-Butyllithium (20mmo1, as 15 % solution in n-pentane)
is added to (I) (IOmmol) in anhydrous tetrahydrofuran (SO100ml) at -78°C with stirring under very pure nitrogen.
After reaction under the conditions listed in Tables 1 and
2 the reaction mixture is hydrolyzed with 20% ammonium
chloride solution (IOOml), the phases separated, the nonaqueous phase dried over sodium sulfate, the solvent removed
under reduced pressure in a rotary evaporator, and the residue
fractionated. In the reaction with pyridines the crude product
Angrw. Chem. Int. Ed. Engl. / Vol. 15 (1976) N o . 7
is not fractionated but instead dissolved in ether, filtered,
and, after removal of the ether, recrystallized from acetonitrile
or vacuum sublimed.
Received: March 19, 1976 [Z 443 IE]
German version: Angew. Chem. 88, 444 (1976)
CAS Registry numbers;
( l a j , 36601-47-5; ( l b ) , 18032-39-8;
( l e i , 17828-44-3; ( I f ) , . 58933-93-0;
( 2 b j , 58933-95-2; ( 2 c ) , 58933-96-3;
( 2 f ) , 58933-97-4; ( 2 g ) , 58933-98-5;
( S c l , 58934-01-3; ( 5 d i , 58934-02-4;
(6b1, 17379-47-4; ( 6 c J , 58934-04-6;
( l c ) , 58933-92-9;
( l g ) , 58933-94-1 ;
( 2 d ) , 17881-95-7;
( S R ) , 58933-99-6;
( S e ) , 58934-03-5;
( 6 d ) , 58934-05-7;
( I d ) , 36971-28-5;
( 2 a ) , 15288-53-6:
( 2 e ) , 13132-25-7;
( S b ) , 58934-00-2;
(60). 17379-48-5;
( 6 e ) . 58934-06-8
J . Pfletschinger, Dissertation, Universitat Stuttgart 1975.
[ 2 ] R . West, R . Lowe, H. F . Stewart, and H . Wright, J . Am. Chem. SOC.
93, 282 (1971); R . West and A . Wright, ibid. 96, 3214 (1974); A. Wright
and R . West, ibid. 96, 3227 (1974).
[3] G. A. Gornowicz and R . West, J. Am. Chem. SOC.90, 4478 (1968); R.
West and G. A. Gornowicz, J. Organomet. Chem. 28, 25 (1971).
[4] I . F. Lutsenko, Yu. 1. Baukoa, G . S. Burlaclrenko, and B. N . Khasapou,
[I]
J. Organomet. Chem. 5 , 20 (1966).
We have determined the coalescence temperatures of compounds (2) and calculated the free energy of activation A G *
for inversion using the Eyring equation:
AG+=4.57 T,(9.97+log$)
( T ,=coalescence temperature, Av = maximum difference
between the chemical shifts of the methyl groups). The results
are listed in Table 1. Mislow et al.[*] have determined a free
activation energy of 36 kcal/mol for inversion in the metal-free
phospholane ( 3 ) .
As can be seen from Table 1, there is an almost linear
relationship between the free energy of activation of inversion
at the phosphorus atom and the electronegati~ity[~I
of the
neighboring metal or carbon atoms. These results are in agreement with the observations by Mislow, et al.r41on the corresponding open-chain phosphanes.
Received: February 17, 1976 [Z448 IE]
German version: Angew. Chem. 88.445 (1976)
Inversion at Phosphorus in Sila-, Germa-, and Stannaphospholanes [**I
By C. Couret, J . Escudik, J . SatgP, and G. Redoul2s[*]
We recently reported the synthesis of the first sila-, germa-,
and stannaphospholanes ( I )[I1. The 2,2-dimethyI-l -phenyl
derivatives (2) of these compounds are particularly well suited
for dynamic NMR investigations, since the diastereotopic
methyl groups give rise to two very pronounced doublets
in the NMR spectrum (Table 1).
ill: M
7
R\
RXM,P
I
R'
= Si,
By Werner Spielmann and Armin de Meijerep]
Bridgehead derivatives of trishomobarrelene ( I a ) ( ' ] and
' well as the unsubstituted
of trishomobullvalene ( 2 ~ ) ~ as
hydrocarbon ( 2 a ) itself possess C3 symmetry and are consequently chiral. Such optically active compounds are of interest
in connection with the question whether, and if so to what
extent, the propeller structure of the carbon skeleton makes
a significant contribution to the chiroptical properties.
Optically active compounds ( 1 ) and (2) are accessible
by resolution of the racemic carboxylic acids ( I b ) and ( 2 b ) ,
respectively. Resolution of the diastereomeric salts with
= Si, R = Me, R' = P h
= G e , R = M e , R' = P h
( 2 c j : M = Sn, R = M e , R'
[I] C. Courer, J . Escudib, J . Surge, and G. Redoul25, C.R. Acad. Sci., Ser.
C, 279, 225 ( 1 974).
[ 2 ] W Egan, R. Tang, G . Zon, and K . Mislow, J. Amer. Chem. SOC.92,
1442 (1970).
[3] A . L. Allreed and E. G. Rochow, J. Inorg. Nucl. Chem. 5, 269 (1958);
A . L. Aiired, ibid. 27, 215 (1961).
[4] R . D. Baechler and K . Mislow, J. Amer. Chem. SOC.93, 773 (1971).
Optically Active Bridgehead Derivatives of Trishomobarrelene and Trishomobullvalene[*']
G e , Sn
R = Me, Et, P h
R' = n-Bu, P h
(2a): M
(26): M
CAS Registry numbers:
( 2 a ) , 54770-04-6; ( 2 b ) , 5477047-9; ( Z c ) , 54770-39-7
=
ph
C6H5
Table 1. Physical properties of compounds ( 2 ) and ( 3 )
Cpd.
6Me'
CPPml
J(P-Me')
CHzl
&Mez
[PPml
J(P-Me2j
IHzI
Coalescence
temperature
C"c1
(2a)
(2b)
(2c)
(3)
-0.14 (d) [a]
0.05 (d) [a]
0.02 (d) [b]
1.7
1.75
1.5
0.34 (d) [a]
0.50 (d) [a]
0.42 (d) [b]
7.5
5.25
2.25
140
200
155
AG*
[kcal/mol]
Electronegativity
131
_________
21.3
24.3
21.95
36 PI
Si:1.90
Ge: 2.01
Sn:1.96
C: 2.55
[a] In [DJacetone rs. tetramethylsilane as internal standard.
[b] Neat, u.tetramethylsilane as internal standard.
['I
Dr. C. Couret, Dr. J. Escudie, Prof. J. Satge ['I, Dr. G. Redoulks
Universite Paul Sabatier
Laboratoire de Chimie des Organomineraux
11 8, Route de Narbonne
F-31077 Toulouse-Cedex (France)
['I Author to whom correspondence should be addressed.
[**I The authors wish to thank Professor K . Mislow for critical examination
of the manuscript and Dr. J.Parello, Montpellier University, for his participation in the NMR investigation of the germaphospholane ( 2 b ) .
Angrw. Chem. I n r . Ed. Engl. / Vol. 15 ( 1 9 7 6 ) N o . 7
[*I
DipLChem. W. Spielmann and Prof. Dr. A. de Meijere
Organisch-Chemisches Institut der Universitat
Tammannstrasse 2, 3400 Gottingen (Germany)
[**I Presented in part at the "Chemiedozententagung" (April 1975) at Dusseldorf and the Eleventh Euchem Burgenstock Stereochemistry Conference
(April/May 1975).-This work was supported by the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie, BASF AG, and Deutsche
Shell-Chemie GmbH.
429
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