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Disilene versus Silanediyl (УSilyleneФ) Additions to CN and NCO Bonds.

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The structures of 6a (Cs),7a (Cl), 8a (C2”)and 10b ( C , )
were deduced from the number and multiplicity of their
“C-NMR signals. The structures of 6b ( C , ) and 7b (C,)
could be assigned on the basis of the coupling patterns of
their vinyl proton signals (6b: 6= 5.32, dd, J = 1.6 and 3.3
Hz, 1 H ; 7b:6=4.94, q, J=8.0 Hz, 1 H). 8b (C,) was identified by comparison of its I3C-NMR spectrum with that of
8 a . Attempts to oxidatively cleave the double bond of 8b
have thus far failed. Ozonolysis afforded the epoxide 11
(m.p. 145“C, 52Y0),’~.~]
while an attempted subsequent
cleavage with periodic acid in anhydrous etherL8]furnished
the ketone 12 (m.p. 155”C, 45%).[31
[6] W. K. Wilson, G. J. Schroepfer. Jr., J. Org. Chem. 53 (1988) 1713.
[7] Cf. also P. S. Bailey: Ozonation in Organic Chemisfry. Vol. I , Academic
Press, New York 1978, p. 197ff.
[8] L. F. Fieser, M. Fieser: Reagents for Organic Synthesis. Vol. 1 . Wiley,
New York 1967, p. 817.
191 D. Ginsburg, Top. Curr. Chem. 137 (1987) I .
Disilene uersus Silanediyl (“Silylene”) Additions
to CN and NCO Bonds**
By Manfred Weidenbruch.* Bolko Flintjer, Siegfried Pohl.
and Wolfgang Saak
Despite bulky ligands, which are necessary for the stabilization of the SiSi double bond (“embedded double
bonds”), disilenes are more reactive than alkenes bearing
sterically less demanding substituents, and, in some cases,
undergo reactions atypical for CC double bonds.”] For example, alkenes do not undergo [2 2]-cycloadditions with
nitriles.[21We have now found, however, that tetra-tert-butyldisilene 3, formed on photolysis of hexa-tert-butylcyclotrisilane 1 J31 reacts smoothly with tri-tert-butylsilyl cyanide
4I4Ito give the 2,3-disila-l-azetine 5 .
In contrast, nitriles RCN with smaller substituents R
react with 2 to give preferentially azasilirenes 6, which
spontaneously undergo o-dimerization to give 1,4- or 1,3diaza-2,5-disila-l(6),3-~yclohexadienes7.15’Formation of
the intermediates 6 could be confirmed indirectly by the
analogous reaction with phosphalkynes, from which stable
phosphasilirenes are isolable.[61 Apparently the bulky
+
11
12
These findings show that suitably substituted tetraspiranes can be used for the synthesis of bispropellanes. The
realizability of such transformations had already been predicted by Ginsburg.‘’] A verification of the equilibria via
equilibration experiments with 6a,b,7a,b, 8a,b and 10b
has not yet been carried out. The route to trispropellanes,
however, would appear open.
Received: July 18, 1988:
supplemented: September 18, 1988 [ Z 2870 IE]
German version: Angew. Chem. 101 (1989) 55
[I] L. Fitjer, U. Quabeck, Angew. Chem. 99 (1987) 1054: Angew. Chem. Int.
Ed. Engl. 26 (1987) 1023.
[2] Program MM2: N. L. Allinger, J . Am. Chem. Sor. 98 (1977) 8127. In the
case of 6s (6b) 6(8), in the case of 7a (7b) 8(24), and in the case of 8 a
(8b) 7(10) conformations had to be optimized symmetrywise in their
geometry and investigated with regard to their enthalpy of formation before the respective global minima were established. In the case of 6 a and
6 b only chair conformations were considered.
131 All the new compounds (4a,b, 6a,b, 7a,b, 8a.b. lob, 11, 12) gave cor’,Crect analyses and/or high-resolution mass spectra. The IR, ‘H-,
NMR and mass spectra are consistent with the given structures. The stereochemistry quoted for 10b is based on force-field calculations and is
tentative. ”C-NMR data 20 and 50 MHz (4a, 7a,b): 4 a (C6D,):
6 = 16.59, 17.03, 25.61, 25.64, 25.81 (C,,,), 25.88 (C,,,,), 27.18 (C,,,), 54.55,
57.56, 80.68 (C,,,,,); 4 b (CeD6): 6=8.65 (C,,,,), 16.39, 16.70, 25.62, 25.67,
26.01, 26.65, 31.29 (C,& 55.02, 57.75, 81.82 (C,,,,,):
6a (CDCI,):
F = 19.07,27.83, 33.31, 34.32,38.02,38.35 (C,,,), 59.46, 62.00(CqU,,,), 96.82
(C,,,), 169.32 (Cqwar,);6 b (CDCI,): S= 12.97 (C,,,,), 19.14, 24.80, 26.03,
27.72, 33.18, 34.32, 35.41, 35.75, 36.94, 38.56, 39.09, 39.53 (C,,,), 60.07,
60.89, 62.19, 62.78 (Cquar,),108.18 (C,,,,), 159.18 (C,,,,,); 7a (CDCI,):
6=24.51 (C,,,,), 25.14, 25.90, 26.39, 33.74, 38.09, 38.22, 38.52, 38.78,
39.27, 39.81, 41.41 (C,,,), 50.30, 61.72, 68.37, 71.19 (C,,,,,), 116.55 (C,,,,),
165.08 (C,,,,,); 7 b (CDCI,): 6= 10.12 (C,,,,), 24.80, 26.14, 26.71, 28.99,
33.77, 34.87, 37.39, 38.05, 38.58, 39.37, 39.85, 40.27 (C,,,), 54.40, 61.63,
68.38, 71.27 (C,,,,,), 117.16 (C,,,,), 164.36 (C,,,,,); 8a (CDCI,): 6=26.93,
39.12, 43.66 (C,,,), 65.08, 71.13 (C,,,,,). 104.15 (C,,,), 173.91 (CqUar,):8 b
(CeD,): 6=15.22 (C,,,,), 27.21, 27.73, 39.32, 39.66, 43.10, 44.45 (C,,,),
64.78, 67.03, 69.47, 72.15 (C,,,,,), 114.91 (C,,,,), 164.32 (Cquar,): 10b
(CDCI,): 6 = 14.24 (C,,,,), 19.56, 24.02, 25.64, 28.34, 28.75, 31.12, 34.54,
36.71, 38.40, 39.18, 40.27, 46.26 (C,,,), 50.22, 55.43 (C,,,,,), 58.13 (C,,,,),
59.35 (C,,,,l), 109.91 (C,,,,), 149.31 (C,,,,,); 11 (CDCI,): 6 = 15.27 (C,,,,),
25.82, 26.34, 26.95, 27.26, 34.90, 37.12, 37.91, 38.56, 38.64 (coincidence of
two lines), 40.46, 41.00 (C,,,), 54.24 (C,ecJ,65.47, 66.78,67.75,68.85, 73.67
(C,,,,,); 12 (CDCL): 6=25.21, 26.41, 31.56, 37.78, 37.93 (coincidence of
two lines), 41.82, 67.07, 67.12, 69.29, 209.62.
141 Nafion NR50 (Aldrich-Chemie, D-7924 Steinheim (FRG)) was activated
for 12 h at 105”C/20 torr immediately before use.
151 M. Saunders, J. Chandrasekhar, P. von R. Schleyer in P. de Mayo (Ed.):
Rearrangements in Ground and Excited States. Vol. 1. Academic Press,
New York 1980, p. 4.
Angew. Chem. Int. Ed. Engl. 28 (1989) No. I
fBu,
hv
--+
/si\
fBu,Si -SSi
tBu,
tBu2Si:
+
tBu2Si=SitBu2
3
2
1
LRCN
tBu,
Si
7
6
f Bu,SiCN
tBu,
\C=N:I
/ \
RC =N:
-Si
fBu,Si
/
tBu,Si
6
5
tBu3Si group prevents addition of 2 to 4 to give the ringstrained 6 (and its dimerization to 7) and thus favors the
[2 21-cycloaddition to give 5 . The formation of 5 by addition of 2 to 4 (+ 6)with subsequent silanediyl insertion in
the Si-C or Si-N bond cannot be completely ruled out.
However, such insertion reactions only take place at higher
ternperat~res‘~]
and should, in this case, be further irnpaired by the bulky substituents.
The spectroscopic data contribute very little to an elucidation of the constitution of 5,”’ for the C=N stretching
vibration, which normally appears between 1560 and 1605
cm-’ in the case of SiC=NSi compounds,[51is not ob-
+
[*] Prof. Dr. M. Weidenbruch, B. Flintjer, Prof. Dr. S . Pohl,
DipLChem. W. Saak
[**l
Fachbereich Chemie der Universitat
Carl-von-Ossietzky-Strasse 9- 1 1, D-2900 Oldenburg (FRG)
Silicon Compounds with Strong Intramolecular Steric Interactions, Part
34. This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen 1ndustrie.-Part 33: M. Weidenbruch,
A. Schafer, H. Marsmann, J . Organomer. Chem. 354 (1988) C 12.
0 VCH Verlagsgesellschaji mbH. 0-6940 Weinheim, 1989
0570-0833/89/0101-0095 $ 02.50/0
95
served. An X-ray structure analysis of 5['] (Fig. l), on the
other hand, revealed some especially informative features:
The four ring atoms and the exocyclic Si atom lie exactly
in a plane. The steric crowding of the molecule not only
forces a stretching of all ring bonds but also leads to a substantial widening of the Si2-Cl-Si3 angle to 144". As expected, the smallest bond angles inside the ring occur at
the Si atoms.
takes place. This can be regarded as indicative of a similar
reaction of 8 with 3.
82
71
3
43
hSi3
33
Fig. 2. Crystal structure of 9 (without H atoms). Selected bond lengths [pm]
and angles ["I (standard deviations): CI-Si2 202.2(3), Si2-0 166.2(2), 0-Si3
165.6(2), Si3-N 177.4(2), N-Cl 129.0(3), Cl-Sil 196.7(3); CI-Si2-0 93.8(1),
SiZ-O-Si3 118.4(1), 0-Si3-N 99.2(1), Si3-N-C1 118.5(2), N-Cl-Si2 110.1(2).
b
Experimental
9
5 : A solution of 1 (0.65 g, 1.53 mol) and 4 (1.00 g, 450 mL) in 70 m L of n-
16
Fig. 1. Crystal structure 01' 5 (without H atoms). Selected bond lengths [pm]
and angles ["I (standard deviations): Sil-Si2 179.8(2), C l - N 130.4(3), C I S 2
199.6(3), CI-Si3 195.4(3); Sil-N-Cl 109.7(2), N-C1-Si2 104.8(2), CI-Si2-Sil
69.5(1), N-Sil-Si2 75.8(1), Si2-Cl-Si3 143.9(1).
Less unambiguous from the mechanistic standpoint is
the photolysis of 1 in the presence of tri-tert-butylsilyl isocyanate
which we have investigated as first example
for the reaction behavior of 3 (or also of 2) towards cumulated double-bond systems, Here again a compound is isolated which is formally composed of 3 and 8 in a ratio of
1 : 1. The obvious assumption that the product"'] is formed
by [2+2]-cycloaddition of 3, either at the C O or at the
C N double bond,["' is disproved by the X-ray structure
analysis[" (Fig. 2), which rather indicates that multiple
cleavage and recoupling of bonds leads to formation of the
3-aza-l-oxa-2,5-disilacyclopent-3-enederivative 9. The
formation of 9 not only requires rupture of the CO bond
and insertion of the oxygen between two Si atoms, but also
migration of the bulky tBu,Si group from the N atom to
the C atom. All the more astonishing is that the rearrangement takes place under the mild reaction conditions
chosen here. Attempts to trap intermediates with other isocyanates have so far failed.
recently found that the reaction of the staWest et a1.[t21
ble tetramesityldisilene with nitrobenzene is initiated by a
[2 3]-cycloaddition of the Si=Si bond to the oxygen
atoms of the nitro group at which, as in the case of 9, a
rearrangement with formation of the disiloxane finally
+
96
0 VCH Verlagsgesellschafr mbH, 0-6940 Weinheim. 1989
hexane was irradiated with a mercury high-pressure lamp (Heraeus TQ150)
until the initially yellow solution was almost colorless. The residue remaining
after removal of n-hexane by distillation furnished, after repeated recrystallization from n-pentane, 0.35 g of crystalline 5 (30% yield, based on 3). Additional 5 remained unpurified in the mother liquor (NMR signals).
9 : Analogously to the synthesis of 5 , a solution of 1 (0.85 g, 2.0 mmol) and 8
(1.40 g, 5.9 mmol) in 60 m L of n-hexane afforded 0.32 g (20%) of crystalline
9. Similarly as in the case of 5 , according to an NMR analysis additional 9
remained unpurified in the mother liquor.
Received: August 1, 1988 I2 2897 IE]
German version: Angew. Chem. 101 (1989) 89
[ I ] Review: R. West, Angew. Chem. 99 (1987) 1231; Angew. Chem. Int. Ed.
Engl. 26 (1987) 1201.
[2] See, for example: G. Tennant in D. Barton, W. D. Ollis, I. 0. Sutherland
(Eds.): Comprehensiue Organic Chemistry. Val. 2, Pergamon Press, Oxford 1979, p. 385; D. E. Davies, R. C. Storr in A. R. Katritzky, C. W.
Rees, W. Lwowski (Eds.): Comprehensiue Heterocyclic Chemistry, Val. 7,
Part 5. Pergamon Press, Oxford 1984, p. 237.
131 A. Schafer, M. Weidenbruch, K. Peters, H. G. von Schnering, Angew.
Chem. 96 (1984) 311; Angew. Chem. Int. Ed. Engl. 23 (1984) 302.
[4] M. Weidenbruch, H. Pesel, Z. Naturforsch. 8 3 3 (1978) 1465.
[5] M. Weidenbruch, A. Schafer, K. Peters, H. G. von Schnering, J. Organomef. Chem. 314 (1986) 25.
[6] A. Schafer, M. Weidenbruch, W. Saak, S. Pohl, Angew. Chem. 99 (1987)
806; Angew. Chem. Int. Ed. Engl. 26 (1987) 776.
[7] T. J. Barton, J. A. Kilgour, J . Am. Chem. Soc. 98 (1976) 7746; D. Seyfenh, D. C. Annarelli, D. P. Duncon, Organometallics l(1982) 1288.
[8] 5 : orange-yellow platelets, m.p. 117-1 19°C; 'H-NMR (300 MHz, C,D,):
S= 1.29 (s, I8H), 1.345 (s, 45H): (C6Dl2): 6= 1.297 (s, 27H), 1.322 (s,
18H). 1.335 (s, 18H); MS (CI, isobutane): m / z 510 (MH", loo%), correct C,H,N analysis.
[9] 5 : monoclinic, space group P 2 , / c (No. 14). a=1712.9(1), b=1119.1(1),
c = 1793.8(1) p m : p = 104.06(1)". Y=3335.5. lo6 pm': Z=4,pC,,,,= 1.016
gem-', 4852 independent reflections observed ( I > 2u(I)) 4237, number
of variables 298, empirical absorption correction, R=0.055,
R,, =0.054.-9:
triclinic, space group Pi (No. 2). n=894.3(1),
b = 1176.I(l), c = 1605.2(1) pm, a=98.06(1), fi=90.90(1), y=92.89(1)".
V = 1669.1 - lo6 pm'; Z = 2 , pcalcd=1.023 g em-', 5167 independent reflections observed (f>2u(1)) 3566, number of variables 433, R=0.047;
R, = 0.043.-Further details of the crystal structure investigations are
available on request from the Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-7514 Eggenstein-Leopoldshafen 2 (FRG), on
quoting the depository number CSD-53309, the names of the authors,
and the journal citation.
0570-0833/89/0101-0096 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 28 (1989) No. I
(101 9 : pale green platelets, m.p. 191-194°C; 'H-NMR (300 MHz, C6Dh):
h'= 1.24 (s, ISH), 1.26 (s, I8 H), 1.345 (s, 27H); MS (CI, isobutane): m / z
526 (MH@,100°/o); correct C,H,N analysis.
[ I I 1 M. Weidenbruch, B. Flintjer, S. Pohl, W. Saak, J. Martens, J . Organomer. Chem. 338 (1988) C 1.
[I21 R. West, private communicastion (August 9, 1988). Editorial note: see G.
R. Gillette, J. Maxka, R. West, Angew. Chem. I01 (1989) 90; Angew.
Chem. I n t . Ed. Engl. 28 (1989) 54.
We now report the first synthesis and characterization of
the relatively stable salts of thiosulfinic acids la-c, whose
stability may be due to the sterically demanding substituents at the central sulfur atom.
H,S. RN
,'
RSCl
ll
0
4
Thiosulfinic Acids:
a New Class of Chiral Organosulfur Compounds**
By Marian Mikoiajczyk, * Piotr t y z w a , Jdzef Drabowicz.
Michaf Wieczorek, and Grzegorz Bujacz
Dedicated to Professor Friedrich Cramer on the occasion
of his 65th birthday
The well-known sulfinic acids RS0,H1',21are effectively
achiral because their anions are symmetrical and therefore
achiral. Replacement of one of the two oxygen atoms in
this anion by sulfur formally leads to the thiosulfinic acids
RSOSH 1, for which both the acid and its anion are chiral.
However, to the best of our knowledge this class of organosulfur compounds has not yet been described. The only
known compounds, which may be regarded to be formally
derived from thiosulfinic acids, are the thiosulfinates
RS(O)SR,"' which were also obtained in optically active
f0rm.1~1
R'
=
>
No,CO,
2 R'~NH@
Et,O oder
CH;CI,,
- 7OoC
XQCP
2 . No@
X@
Me, Et;
1
+RSSO
X@
II
0
2.XQ
0
= HPN=C=NH,
I
SCH,Ph
Reaction of the sulfinyl chlorides 4a-c with hydrogen
sulfide and trialkylamines at -70°C in ether or dichloromethane gave, in high yields (75-87%), the ammonium
salts of the acids 2. For ease of characterization these salts
were converted first into sodium and then into S-benzylthiuronium salts. ' H and 13C N M R spectra of the salts
thus obtained are consistent with the thiosulfinic acid
structure (Table 1).
Table 1. Selected ' H and "C NMR data for salts of the thiosulfinic acid 1.
~~
~_______
2a. Me3NHe [a]: ' H NMR (60 MHz, TMS,,,, CDCI,): 6 = 1.15 (s, 9 H ;
Me,C), 2.80 (s, 9 H ; Me,N); "C{'H) NMR (22.63 MHz, CDCI,): 6=22.74
(Me2C),43.53 (Me,N), 52.7 (Me,C-)
RS-SE
II
RS-SH
/I
0
0
11
S
II
S
II
RS:O
11
-H
RS-H
ll
0
&
+ H@
+ EQ
+
2 c . Nae [c]: 'H NMR (300 MHz, TMS,,,, CD,OD): 6=5.34 (s, I H; HIO),
S
/I
RS-E
I1
0
0
11
RS=S
RS=S
I
0-H
0-E
I
1
2
2b. Xe [b]: ' H NMR (60 MHz, TMS,,,, CD,OD): 6= 1.7-2.5 (m. 15H; Ad),
4.40 (s, 2 H ; CH,Ph), 4.85 (s, 4 H ; NH2), 7.40 (s, 5 H ; Ph); "C{'H) NMR
(38.93 MHz, CDCI,): 6=30.65, 36.61, 43.89 (Ad), 36.75 (CH,Ph), 66.33 (C-l
of Ad), 128.08, 129.48, 129.72, 130.07 (Ph), 138.04 (C(NH,),)
3
7.21-7.35 (rn. 6H), 7.59-7.66 (rn, 3 H), 8.54-8.57 (rn, 1 H), 8.98-9.01 (m, 2H);
"CI'H} NMR (38.93 MHz, CD3OD): 6=56.16 (CIO), 75.56 (C9), 123.90,
124.22, 125.29, 143.64, 143.87, 148.29, 149.67
[a] We have not been able to isolate an analytically pure salt because of slow
decomposition. [b] m.p. 135-140°C (from ethanol); correct C,H,S,N analyses
were obtained. [c] 2c. Et,NHe; m.p. 223-225°C (from chloroform/n-pentane); we have not been able to isolate the analytically pure salt because of
facile oxidation to the corresponding thiosulfonate.
Scheme I
The chiral thiosulfinate anion can be described by three
mesomeric forms (Scheme 1). Therefore, protonation
could lead to three tautomeric forms of the acid 1 and the
reaction with an electrophile Em could result in the formation of three isomeric products.
RSSH
6
a, R = t B u
A final proof of the structure was provided by an X-ray
structure analysis (Fig. 1) of the S-benzylthiuronium salt of
adamantanethiosulfinic acid 2b.@' It showed a slightly distorted tetrahedral arrangement of the substituents (carbon,
oxygen, sulfur and lone electron pair) around the central
sulfur atom in the anion under discussion. The SILO and
Sl-S2 distances of 1.536 and 2.025 A suggest delocalization of the negative charge in the anion.
la-c
b, R = D ( A d )
c.
R
=
&
(Tr)
Zb
[*] Prof. Dr. M. Mikoiajczyk, P. t y i w a , Dr. J. Drabowicz
Centre of Molecular and Macromolecular Studies,
Polish Academy of Sciences
Boczna 5, 90-362 Lodz (Poland)
Dr. M. Wieczorek, G. Bujacz
Institute of General Chemistry, Technical University
Zwirki 36, 90-524 Lodz (Poland)
[**I
This work was supported by the Polish Academy of Sciences and the
Ministry of National Education (CPBP 01.13 and RP.II.10).
Angew. Chem. In,. Ed. Engl. 28 (1989) No. I
Fig. I . Molecular structure of 2 b . Xo.Important bond lengths [A] and bond
angles ["I: CI-Sl 1.845(3), S 1 - 0 1.536(2), SI-S2 2.025(9), C11LS3 1.759(3),
C I I - N I 1.302(4), C l l L N 2 1.318(4), C12-S3 1.826(3); S2-SILO 109.70(8), S2SI-CI 104.74(8), 0-S1-CI 103.12(9), N2-CllLS3 120.9(2), NI-ClILS3
I16.9(2), N2-Cl I-NI 122.2(2).
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