close

Вход

Забыли?

вход по аккаунту

?

Bridged [14]Annulenes with a Phenanthrene-Perimeter anti-1 6 7 12-Bismethano[14]annulene.

код для вставкиСкачать
Bodwell, K. S. Weerawarna, W. Anker, R. V. Williams, G. W. Bushnell,
Pure Appl. Chem. 58 (1986) 15; b) the same holds for the bridged [14]annulenes with "azupyrene perimeter" (annelated systems of two azulene
units): W. Huber, J. Lex, T. Meul, K. Miillen, Angew. Chem. 93 (1981)
401: Angew Chem. In/. Ed. Engl. 20 (1981) 391; W. Huber, W. Irmen, J.
Lex, K. Mullen, Tetrahedron Lett. 23 (1982) 3889.
[7] E. Vogel. T Schieb, W. H. Schulz, K. Schmidt, H. Schmickler, J. Lex,
Anyew Chem. 98 (1986) 729: Angew. Chem. In/. Ed Engl. 25 (1986)
723.
[S] Cyclopropabenzene syntheses: a) E. Vogel, W. Grimme, S. Korte, Tetrahedron Lett. IY65, 3625; b) W. E. Billups, A. J. Blakeney, W. Y . Chow,
Chem. Commun. 1971. 1461; Org. Synth. 55 (1976) 12.
[9] R. Okazaki, M. 0 - o k a , N. Tokitoh, Y. Shishido, N. Inamoto, Angew.
Chem. 93 (1981) 833: Angew. Chem. Int. Ed. Engl. 20 (1981) 799.
[ 101 a) A. S. Kende. L. S. Liebeskind, D. M. Braitsch. Tetrahedron Lett. 1975,
3375: b) M. Zembdyashi, K. Tamao, J. Yoshida, M. Kumada, rbid. 1977.
4089: c ) R. H. Mitchell, M. Chaudhary, T. W. Dingle, R. V. Williams, J.
Am Chem. Soc. 106 (1984) 1776. and references cited therein.
1111 a ) T. Mukaiyama, T. Sato, J. Hanna, Chem. Lett. 1973. 1041; b) J . E.
McMurry, M . P. Fleming, J . Am. Chem. Soc. 96 (1974) 4708; J . E.
McMurry, Acc. Chem. Res. 16 (1983) 405: c) D. Lenoir, Synrhesis 1977,
553. We thank W H. Schulz for the optimization of the reductive coupling of 9 with titanium tetrachloride/zinc/pyridine.
1121 a) K. B. Sharpless, M. A. Umbreit, M. T. Nieh, T. C. Flood, J. Am.
Chem. SOC.94 (1972) 6538: b) E. Vogel in H. Nozaki (Ed.): Current
Trend.s in Organic S-wthesis. Pergamon Press, Oxfotd 1983, p. 379.
[I31 H Ciinther, Tetrahedron Lett. 1967. 2967. The statements about the
bond alternation in 3 still hold when taking into account the dependence of the coupling constants 'JH.H on the dihedral angle; see hereto:
M. Karplus, J . Am. Chem. Soc. 84 (1962) 2458.
[I41 H.-R. Blattmann, W. A. Boll, E. Heilbronner, G. Hohlneicher, E. Vogel,
JLP. Weber, Helu. Chim. Acta 49 (1966) 2017.
[ 151 Electronic spectra of 3 and 4 : B. Boersch-Pulm, M. Demmer, P. S. Murthy, J . Lex, T. Schieb, G. Hohlneicher, J. Michl, E. Vogel, J. Am. Chem.
Soc.. submitted for publication.
1161 3 crystallizes in the triclin-ic system; space group PI, 0=9.503(1),
h= lI.210(l), c=21.919(1) A, a=84.31(1), /7=83.27(1), y=76.53(1)",
Z = 8 ; 6716 reflections, R=0.052. Further details of the crystal structure
investigation are available on request from the Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-7514 Eggenstein-Leopoldshafen 2, on quoting the depository number CSD-51939, the names o f the
authors, and the full citation of the journal.
Bridged I141Annulenes with a Phenanthrene-Perimeter :
anti-1,6 :7,12-Bismethano[l41annulene**
By Emanuel Vogel, * Thomas Schieb, Wolfgang H . Schulz,
Klaus Schmidt, Hans Schmickler, and Johann Lex
The syn-1,6:7,12-bismethano~l4]annulene1 derived
from phenanthrene, a bridged [14]annulene with a
markedly bent annulene ring, is kind of a borderline case
of an aromatic molecule regarding its n-electron structure."] In the case of the still unknown anti-1,6:7,12-bismethan01 14lannulene 2 the predictions are that one is dealing
with a n olefinic molecule since, according to models, 2
possesses a puckered annulene ring in which the CC bonds
are, in part, strongly twisted (maximum torsional angle 8085 "). Following the successful synthesis of
we are
now also able to report the synthesis of 2.
1
CO,CH,
8
[*] Prof. Dr. E. Vogel, Dr. T. Schieb, W. H. Schulz, K. Schmidt,
Dr. H. Schmickler, Dr. J. Lex
lnstitut fur Organische Chemie der Universitat
Greinstrasse 4, D-5000 Koln 41 (FRG)
This work was supported by the Deutsche Forschungsgemeinschaft
Anyew Chrm I n t . Ed Engl 25 (1986) No 8
j?
1
G 3O COOH
o H
H3C0,C
2
~
[**I
The surprising observation that reductive coupling of
1,l '-bis(~ycloheptatrienyl)-6,6'-dicarbaldehydeexclusively
affords the syn-isomer 1 suggested the idea of approaching
2 by way of its dihydro derivative 1 1 . Compound 11
should be formed, albeit not necessarily stereoselectively,
by reductive cyclization of 6,6'-bis(bromomethyl)- 1,l'bis(cycloheptatrieny1) 9.
The diester 8 could be obtained-more advantageously
than via the cyclopropabenzene route"]-from the readily
accessible cycloheptatriene-l,6-dicarboxylic acid 3,"'
either A) via the dicarboxylic acid dichloride 4, or B) via
the methyl half ester 6Izb1(Scheme
Route A): The
compound 4 (m. p. 63 " C ;yield SO%), prepared by reaction
of 3 with sulfinyl chloride, undergoes selective monodecarbonylation on heating with tris(tripheny1phosphane)rhodium(r) chloride[41as catalyst to give 6-chlorocycloheptatriene-1-carboxylicacid chloride, which after distillation from the reaction mixture is allowed to react with
methanol yielding 5 . Upon chromatographicisolation(silica
gel, ether/pentane l:9), 5 is obtained as an NMR-spectroscopically pure oil, so that for practical purposes a distillation (yellowish liquid of b. p. 62-63 " U 0 . 2 torr;
m. p. 26 " C ; yield 65%) is not required. Treatment of 5
with bis(triphenylphosphane)nickel(Il) chloride (catalytic
amounts) and zinc in tetrahydrofuran (THF) in the presence of tetraethylammonium iodide,Is1 brings about reductive CC coupling to give 8, which after purification by
chromatography (silica gel, ether) and recrystallization
(from methanol) is obtained in the form of yellow rhombs
(m.p. 126-127 " C ; yield 70%). Route B): The half ester 6,
best prepared by hydrolysis of the dimethyl esterlZh1with
aqueous methanolic sodium hydroxide (yield 450/0), can
be decarboxylatively brominated to 7 according to the
method of Barton"] (an alternative to the Hunsdiecker degradation) in that it is converted by reaction with N-hydroxypyridine-2( 1 H)-thione and dicyclohexylcarbodiimide
into the thiohydroxamic ester and the latter then heated in
bromotrichloromethane. After isolation by chromatography (silica gel, ether/pentane I :9) and subsequent distillation, 7 is collected as a yellowish liquid (b. p. 75-76 "C/O. 1
torr; m.p.= 22 " C ; yield 48%). Reductive coupling of 7,
carried out as in the case of 5, affords 8 in 70% yield (no
increase in yield on going from the chloro to the bromo
&H,C
CH,Br
9
Scheme I . A, B see text. a : SOC12, CH2Cl2, reflux, 8 h ; b: tris(tripheny1phosphane)rhodium(~)chloride (Wilkinson catalyst), 165 "C, 3 h; c : methanol, CH2C12, RT, I h ; d : NaOH, methanol/water, RT, 24 h: e : N-hydroxypyridine-2( Ihl)-thione, dicyclohexylcarbodiimide,CBrCli, 120 "C, 4 h: f :
bis(triphenylphosphane)nickel(~~)chloride, tetraethylammonium iodide, Zn,
THF, RT, 18 h; g: DIBAH, ether, RT, 1 h: h : PBr,, pyridine, benzene, 70°C.
5 h.
0 VCH Verlagsgesellschafi mbH. 0-6940 Wemherm, 1986
0570-0833/86/0808-0723
$
!
02.5010
723
compound). The diester 8 can be readily converted into
the dibromide 9 [light-sensitive, yellow cubes (from hexane); decomp. above 115 "C; yield 85%] by reduction with
diisobutylaluminum hydride (DIBAH) in ether [diol isolated: m.p. 132-133 "C; yellow platelets (from ether); yield
95%] followed by bromination with phosphorus tribromide in benzene.
For the intramolecular C C coupling in 9 (Scheme 2), we
resorted to the use of new reductive methods based on
low-valent derivatives of sub-group
The most
convenient method proved to be the reaction of 9 with titanium tetrachloride/zinc/pyridine in THF, since a hydrocarbon mixture consisting mainly of syn- and anri-13,14dihydro-1,6:7,12-bismethano[14]annulene(10 and 11, respectively) is formed,[*] in which 11 predominates. The
separation of the two isomers was accomplished by chromatography on alumina (pentane), whereby 11 was collected as first fraction and 10 as second fraction [ 11 : m. p.
68-69 "C; colorless rhombs (from pentane); yield 52%; 10 :
m. p. 75-76 " C ; yellow needles (from pentane); yield 6%].
The assignment of conformation was confirmed by X-ray
structure analyses of 10 and ll.L91
BrH2C
CH,Br
10
B~H,C
CH,B~
11
structural chemical findings. In the 'H-NMR spectrum of
2 the signals of the annulene protons appear further upfield and those of the bridge protons further downfield
than in the spectrum of 1 [A6 (mean position of the signals) = 0.74 and 1.18 ppm, respectively] (Table 1). The relatively small shift of the signals of the internal bridge protons is understandable, since the signals of the corresponding protons in 1 appear at unusually low field as a result
of the proximity effect.["] In parallel with the changes in
the chemical shifts one finds that the alternation of the vicinal H,H-coupling constants has increased markedly. In
fact, the N M R parameters of 2 relevant to the n-electron
structure of the molecule closely agree with those of its dihydro derivative l l .
Table I . 'H-NMR data (&values and vicinal H,H-coupling constants [Hz])of
the [14lannulene derivatives 1 , 2, 10, and 11 at 300 M H z in CD2C12.
~
~~
H-2
H-3
H-4
H-5
H-I3 [a]
H-1%
H-lSi
1
2
10
11
6.91
6.23
6.00
6.13
7.06
6.67
6.65
6.66
7.27
6.69
6.66
6.81
7.52
6.26
6.51
6.28
7.18
6.40
2.70
2.41
-0.37
1.70
1.00
1.44
2.35
2.64
3.77
2.47
1
2
10
11
6.96
5.94
5.75
5.72
10.26
11.03
10.74
10.77
7.11
5.27
6.00
5.17
[a] The protons H-l3/H-l4 of 10 and 11 appear as an AA'BB' system (data
refer to the mean position of the signals).
"
1c.d
Especially informative is the electronic spectrum of 2,
for this, in contrast to that of 1, no longer exhibits the
three bands["] typical for aromatic [4n 2]annulenes, but
shows only two pronounced bands (Table 2). On the other
hand, the spectra of 2 and anri-1,6:8,13-bismethano[14]ann ~ l e n e [ '(polyene
~'
with fluctuating n-bonds) are strikingly
similar.
For the X-ray structure analysis we used the oxime derivative of anti- 1,6:7,12-bismethano[l4]annulene-2-carbald e h ~ d e . ~The
' ~ ] outcome of the structure d e t e r m i n a t i ~ n " ~ ]
conforms with the image of the molecule that derives from
an inspection of models (Fig. 1). The C C bonds of the annulene ring are, with few exceptions, twisted; the torsional
angles of most of the bonds lie in the range of 22-35 but
+
Scheme 2. a : TiCI?, Zn, pyridine, THF, reflux, 15 h: b : DDQ. anisole,
120°C. 15 h; c : N-brornosuccinimide, CCI,, reflux, 25 h ; d : Nal, acetone,
60°C. 2 h.
The anti-isomer 11 is dehydrogenated (with considerable losses) to 2 by reaction with 2,3-dichloro-5,6-dicyanop-benzoquinone (DDQ) at 250 "C in anisole; surprisingly,
1 is also found to be a product (yields: in each case ca.
5%). In contrast, the syn-isomer 10 experiences DDQ-dehydrogenation already at 120 "C, the product being sterically uniform 1 (yield 75%) (likewise in anisole). These
findings stimulated a study of the thermolysis of 10/11
and 1 / 2 . As it turned out, 10 and 11 interconvert with
bridge inversion at 400 "C in the gas phase (flow apparatus) until an equilibrium (approximate composition: 25%
10 and 75% 11) is established, whereas 1 and 2 are conformationally stable["] under these conditions (above
400 "C irreversible rearrangements take place). I n order to
improve the introduction of the 13,14-double bond, 11 was
allowed to react with N-bromosuccinimide (molar ratio
1 :2.5) in carbon tetrachloride, and the resulting bromide
mixture then heated with sodium iodide in acetone. Chromatography on silica gel (pentane), followed by short-path
distillation (0.3 torr; bath temperature 80 "C)yielded 2 as
a pale yellow liquid (yield 20%).
As expected, anti- 1,6:7,12-bismethano[14]annulene 2 is
borne out as an olefinic compound by spectral data and
724
0 VCH Verlagsgesellschajt mhH. 0-6940 Weinheirn. 1986
O,
Fig. I . Molecular structure of anfr-1,6:7,12-bisrnethano[l4]annulene-2-carbaldehyde oxirne in the crystal: selected bond lengths
Transannular CC
distances: CI . . C6 2.420
C 7 . . . C12 2.407
bridge angles: CI-C15-C6
108.2". C7-CI6-Cl2 106.8".
0570-0833/86/0808-0724 $ 02.50/0
A,
A;
[A].
Angew. Chem. I n t . Ed. Engl. 28 11986) No. 8
Table 2. Some spectral data of the new compounds. ' H - N M R : 300 MHz,
"C-NMR: 75.5 MHz, both in CDC13(exceptions: 2, 10, 11 in CD2CIZ);MS:
70 eV (exceptions: 5, 7 , 75 eV).
2 : ' H - N M R see Table I ; "C-NMR:6=43.32, 117.71, 122.93, 129.40, 129.98,
131.82, 132.15, 135.06; MS: m / z 206 (Me, 38%), 89 (100); IR (film): 3010,
2976, 2906. J637, 1601 c m - l ; UV/VIS (cyclohexane): A,,x,=243 nm
(/;=27200). 275 ( I 1900) sh, 345 (5400)
5 : ' H - N M R - 8=3.04 ( s , 2H), 3.76 (s, 3H), 6.34 (m, 1 H), 6.56 (m, 1 H), 6.58
(m, 1 H), 7 21 (m, I H); "C-NMR: 6=35.40, 52.16, 121 06, 124.23, 125.26,
128.34, 13290, 133.45, 165.80: MS: m / z 186/184(Me, 15/44%), 169(100); IR
(film): 2948, 1707 (C=O) c m - ' : UV/VIS (CH,CN): 1,,,,=220 nm (&=7900),
275 (3350) \h. 302 (3850)
7 : 'H~NMR:~S=3.17(s,2H),3.78(~,3H),6.51(dd,lH),6.56(d,IH),6.62
(dd, I H). 7.21 (d, I H); "C-NMR: 6=37.60, 52.25, 113.91, 121.32, 128.56,
128.63, 133.45, 133.67, 165.79; MS: m/z230/228 ( M Q ,43/46*/0), 215 (100); I R
(film): 3005, 2955, 1717 (C=O) c m - ' ; UV/VIS (CH,CN): 1,,,=215 nm
(c= 13 IOO), 278 (3550) sh, 305 (4200)
8 : ' H - N M R : 6 = 2 . 8 7 ( s , 4 H ) , 3.71 (s,6H),6.61 (dd,2H),6.93 (dd,2H),7.09
(d, 2H), 7.24 (d, 2 H ) ; "C-NMR: 6=28.86, 51.83, 122.46, 124.87, 128.98,
133.53, 134.50. 135.81. 166.05; MS: m / z 298 (Me, IYo), 179 (100); IR (KBr):
3025, 3000, 2948, 1694 (C=O) c m - ' ; UV/VIS (dioxane): A,,,=240 nm
(/;=51800). 295 (4100), 385 (10900)
9 : ' H - N M R : 6=2.67 ( s , 4H), 3.98 (s, 4H), 6.30 (d, 2H), 6.53 (dd, 2H), 6.62
(d, 2H). 6.76 (dd, 2 H ) ; "C-NMR: 6=31.78, 38.54, 123.84, 125.39, 129.40,
12993. 131.69, 132.61: MS. m / z 370/368/366 ( M e ,5/11/6°/o), 178 (100); IR
(KBr): 3014,2986,2861 c m - ' : UV/VIS (dioxane):A,,,=238 nm(s=38600),
282 (5600), 360 (12000)
10: ' H - N M R see Table I ; "C-NMR: 6=35.75, 121.13, 122.55, 123.33,
128.34, 129.61, 130.50: MS: m / z 208 (Me.40%), 178 (100); IR (KBr): 3010,
2976, 2906. 1637, 1601 c m - ' ; UV/VIS (cyclohexane): A,,,,=258 nm
(c= 14700), 352 (8100)
11: ' H - N M R seeTable I ; "C-NMR:6=43.16,48.40, 120.47, 121.05, 129.56,
130.37, 132.28, 133.51: MS: m / z 208 (M", 50%), 178 (100): IR (KBr): 3030,
3002. 2905. 1607, 1587 cm I : UV/VIS (cyclohexane): Am,,,=243 nm
( E = 10 100). 285 (7100)
~
in the case of the C6-C7 bond the torsional angle reaches
the extreme value of 84". As a consequence, the 2p n-orbital overlap at the C6-C7 bond is only barely minimal, and
this obviously accounts for the loss of aromaticity, which
manifests itself in the pronounced alternation of single and
double bonds. The existence of anti-1,6:7,12-bismethano[l4]annulene as the double-bond isomer 2 with cycloheptatriene partial structures['61 follows equally so from
model considerations and force field calc~lations.l"~
Received: March 17, 1986 [Z 1704 IE]
German version: Angew. Chem. 98 (1986) 729
CAS Registry numbers:
1,85385-68-8. 2,85440-62-6; 3, 73875-01-1; 4,73875-02-2,5, 103149-59-3: 6 ,
75538-94-2: 7. 103149-60-6: 8 , 103149-61-7; 8 reduction product (diol),
103149-62-8: 9. 103149-63-9: 10, 103149-64-0; 11, 103238-76-2; anfi-1,6:7,12bismethano[ 14]annulene-2-carbaldehyde 1031-49-65-1 ; an/i-1,6:7,12-bismethano[ 14]annulene-2-cdrbaldehydeoxime 103149-66-2.
[I] a) E. Vogel in H. Nozaki (Ed.): Current Trends in Organic Synthesis.
Pergamon Press, Oxford 1983, p. 379; b) E. Vogel, W. Piittmann, W.
Duchatsch, T. Schieb, H. Schmickler, J. Lex, Angew. Chem 98 (1986)
727; Anqew. Chem. Int Ed. Engl. 25 (1986) 720.
121 a) E. Vogel, H. M. Deger, J . Sombroek, J. Palm, A. Wagner, J. Lex, Angew. Chem. 92 (1980) 43; Angew. Chem. Inr. Ed. Engl. I9 (1980) 41; b)
the acid 3, its methyl half ester 6 and its dimethyl ester were first described by R. Darms. T. Threlfall, M. Pesaro, A. Eschenmoser, Helu.
Chim Arm 46 (1963) 2893.
[3] A new route from cyclopropabenzene to bridged annulenes with cycloheptatriene partial structures [including potential precursors of 21 mediated by transition-metal complexes was recently described by R. Mynott, R. Neidlein, H. Schwager, G. Wilke, Angew. Chem. 98 (1986) 374;
Angew. Chem. fnt. Ed. Engl. 25 (1986) 367; b) for the conversion of cyclopropabenzene into 1,6-methano[lO]annulenes via cycloaddition, see:
E. Vogel, J. Ippen, V. Buch, Angew. Chem. 87 (1975) 592; Angew. Chem.
Inr. Ed. Engl. 14 (1975) 566; E. Vogel, Proc. Roberf A . Welch Found.
Con/ Chem. Re.7. I2 (1968) 215.
Angew. Chem. I n f . Ed. Engl. 25 (1986) No. 8
[4] J. Blum, Terrahedron Leu. 1966. 1605; J . Blum, E. Oppenheimer, E. D.
Bergmann, J . Am. Chem. Soc. 89 (1967) 2338; J . Tsuji, K. Ohno, Tetrohedron Letr. 1966, 4713; Synthesis 1969, 157.
[5] M. Iyoda, K. Sato, M.Oda, J . Chem. Soc. Chem. Commun. 1985. 1547.
[6] D. H. R. Barton, D. Crich, W. 8. Motherwell, Tetrahedron Left. 24
(1983) 4979; for examples of the decarboxylative bromination of aromatic and a,p-unsaturated carboxylic acids, see: D. H. R. Barton, B.
Lacher, S. Z. Zard, ibid. 26 (1985) 5939; in the meantime, Barton's
method has also proven useful in the field of bridged annulenes; for
example, the conversion of 2,7-methanoaza[lO]annulene-9carboxylic
acid into 9-bromo-2,7-methanoazd[ I Olannulene; yield 40% (according to
experiments carried out in collaboration with W . Haas).
[7] CuCl/dimethyl sulfoxide: H. Nozaki, T. Shirdfuji, Y. Yamamoto. Terrahedron 25 (1969) 3461; TiCI,/LiAIH,: G. A. Olah, G. K. S. Prakash,
Synthesis 1976, 607; VCIdLiAIH,: T.-L. Ho, G. A. Olah, ibid. 1977. 170:
WCIJLIAIH,: Y. Fujiwara, R. Ishikawa, S . Teranishi, Bull. Chem. Soc.
Jpn. 51 (1978) 589. Reductive coupling with formation of 10 and 11 was
observed only with the first two methods. The reaction of 9 with sodium
iodidelacetone leads primarily to heptaenes, which on heating undergo
electrocyclization to 10 and 11.
[8] Reaction conditions of the Mukaiyama variant of the McMurry reaction: T. Mukaiyama, T. Sato, J . Hanna, Chem. Left. 1973. 1041; D. Lenoir, Synthesis 1977. 553.
[9] B. Boersch-Pulm, M. Demmer, P. S. Murthy, J . Lex. T. Schieb, G. Hohlneicher, J. Michl, E. Vogel, J . Am. Chem. Soc., submitted for publicdtion.
[lo] For the conformational stability of s w - and anr~-1,6:8.13-bismethano[ 14]annulenes and their 7,14-dihydro derivatives, see E. Vogel, W.
Tuckmantel, K. Schlogl, M. Widhalm, E. Kraka, D. Cremer, Tetrahedron
Leu. 25 (1984) 4925.
[ I I ] H. Gunther: NMR-Spektroskopie. Thieme, Stuttgart 1983, p. 90.
[12] a) H.-R. Blattmann, W. A. Boll, E. Heilbronner, G. Hohlneicher, E. Vogel, J.-P. Weber, Helv. Chim. Acra 49 (1966) 2017: b) H. J. Dewey, H.
Deger, W. Frolich, B. Dick, K. A. Klingensmith, C . Hohlneicher, E. Vogel, J. Michl, J . Am. Chem. Soc. I02 (1980) 6412.
[I31 E. Vogel, U. Haberland, H. Giinther, Angew. Chem. 82 (1970) 510: Angew. Chem. Inr. Ed. Engl. 9 (1970) 5 13.
(141 Reaction of 2 with dichloromethyl n-butyl ether in the presence of tin
tetrachloride [A. Rieche, H. Gross, E. Haft, Chem. Ber. 93 (1960) 881
afforded mainly anri-1,6:7,12-bismethano[
14]annulene-2-carbaldehyde,
which was isolated by thin-layer chromatography (silica gel, penlane/
ether 20:l) as an orange-colored oil (yield 13Oh). Reaction of the aldehyde with hydroxylamine hydrochloride/pyridine furnished the oxime:
bright yellow rhombs (from dichloromethane) of m. p. 172-173 'C.
[ 151 anrr-1,6:7,12-Bismethano[
14]annulene-2-carbaldehyde oxime crystallizes m o n o c l ~ i c a l l y , space group P Z , / c , a = 16.768(4), b = 6.O39( I),
c = 13.270(2) A, 8=99.99(1)", 2 = 4 ; 1290 reflections. R=0.036. Further
details of the crystal structure investigation are available o n request
from the Fachinformationszentrum Energie, Physik, Mathematik
GmbH, D-7514 Eggenstein-Leopoldshafen 2, on quoting the depository
number CSD-51940, the names of the authors, and the full citation of
the journal.
1161 See, however, the double-bond configuration of 1,6:9,14-bismethano[ 16]dnnulene. D. Tanner, 0. Wennerstrom, E. Vogel, Terrahedron Leu.
23 (1982) 1221; E. Vogel, U.Kiirschner, H. Schmickler, J. Lex, 0.Wennerstrom, D. Tanner, U. Norinder, C. Kruger, ibid. 26 (1985) 3087.
[I71 According to calculations with a modified MM2 force field (W. R Roth,
F.-G. Klarner, G. Siepert, H.-W. Lennartz, unpublished) 2 is favored
over its double-bond isomer by no less than 41.2 kcal/mol. I n the case
of 1 , this value drops to 3.6 kcal/mol (W. R. Roth, private communication).
Synthesis of Glycosphingolipids and Psychosines**
By Richard R. Schmidt* and Peter Zimmermann
Glycosphingolipids have acquired great importance as
components of biological membranes."' I n order to explore their role and function in membranes, the synthesis
of isomerically pure compounds that are otherwise only
[*] Prof. Dr. R. R. Schmidt, DipLChem. P. Zimmermann
[**I
Fakultat fur Chemie der Universitat
Postfach 5560, D-7750 Konstanz (FRG)
Glycosylimidates, Part 23. This work was supported by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen 1ndustrie.Part 22: R. R. Schmitt, G. Effenberger, Carbohydr. Res.. in press.
0 VCH VerlagsgesellschaJi mbH, 0-6940 Weinheim. 1986
0570-0833/86/0808-0725 $ 02.50/0
725
Документ
Категория
Без категории
Просмотров
1
Размер файла
391 Кб
Теги
annulenes, phenanthrene, annulene, bridge, perimeter, anti, bismethano
1/--страниц
Пожаловаться на содержимое документа