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Deep-Colored Through-Conjugated Multitriphenylmethylium Ions.

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mined the thickness of the membranes from measurements
of the electrical capacity on “black films” (black bilayer
membranes BLM).“’.”l Bilayer membranes with remarkable longevity (up to several hours) and stability toward
higher potentials (measurements u p to 300 mv) could be
obtained (surface areas 0.15 mm’) from 3-4% solutions of
4 - 7 in n-decane/n-butanol (100 : 1). The specific membrane capacities measured at potentials of 10-300 mV (Table 1) lie about a factor of 1.5 above those of phosphatidylTable I . Specific membrane capacity (C,) and thickness ( d ) of the hydrocarbon region of the bilayer membranes of lactosylceramides 4 - 7 [a].
Compound
C , [pF/cm’] [b]
d Inml Icl
0.563 t 0 . 0 7 2
0.755 kn.073
0.8 I8 t0.092
n.s7ot0.038
3.30+0.26
2.46 t0.25
2.27 0.20
3 . 2 6 t 0.49
[lo] P. Miiller, D. 0. Rudin, H. T. Tien, W. C. Wescott, Nature London 194
(1962) 979.
[ I I ] P. Lauger, W. Lesslauer, E. Marti, J. Richter, Biochim. Biophys. Acfu 135
(1967) 20.
1121 R. Benz, 0. Frohlich, P. Lauger, M. Montal, Biochim. Biophys. Acfu 394
(1975) 323; R. Benz, K. Janko, rbid. 455 (1976) 721. Specific membrane
capacities of various phospholipids are presented in this publication.
Deep-Colored, Through-Conjugated
Multitriphenylmethylium Ions**
By Dieter Hellwinkel.* Heinz Stahl, and
Heinrich Ceorg Gaa
+
[a] For details of the measurements see Refs. [9-121 and literature cited therein. [b] Mean value of ten measurements. [c] For calculation see Ref. [ I I].
Monocationic “conventional” triphenylmethylium dyes
of the crystal violet type 1 and the tricationic “inverse”
analogues 2 derivable from them by exchanging the functionalities show almost the same longest-wavelength absorptions in the electronic spectrum and have virtually the
same green color.“]
choline membranes.l’21 This can be due to the altered dielectric properties of the hydrophilic head groups in the case
of the lactosylceramides, or to the bilayer being thinner
due to tighter coiling and kinking of the lipid moiety. The
specific membrane capacities increase with the increasing
number of cis double bonds in the C,,-acid derivatives 46, whereas, conversely, the estimated layer thickness for
the lipid moiety, presumably determined by the kinking,
decreases. The specific membrane capacity of the arachidonic acid derivative 7 is of the same order of magnitude
as that of the oleic acid derivative 4, i.e. the chain lengthening by two C-atoms is balanced out by about three additional cis double bonds.
Received: April 6, 1987 [Z 2180 IE]
German version: Angew. Chem. 99 (1987) 813
[ I ] R. R. Schmidt, Angew. Chem. 98 (1986) 213; Angew. Chem. Int. Ed.
Engl. 25 (1986) 212; R. R. Schmidt in W. Bartmann, K. B. Sharpless
(Hrsg.): Stereochemistry of Organic und Bioorganic Trunsformafions.
VCH Verlagsgesellschaft. Weinheim 1987, p. 169, and references cited
therein.
[2] N. K. Kochetkov, G. P. Smirnova, Adv. Curbohydr. Chem. Biochem. 44
(1986) 387, and references cited therein.
[3] R. R. Schmidt, P. Zimmermann, Angew. Chem. 98 (1986) 722; Angew.
Chem. Inf. Ed. Engl. 25 (1986) 725.
[4] A. K. Akimoto, L. Dorn, H. Gros, H. Ringsdorf, H. Schupp, Angew.
Chem. 93 (1981) 108; Angew. Chem. Int. Ed. Engl. 20 (1981) 90.
[ 5 ] R. R. Schmidt, J . Michel, M. Roos, Liebigs Ann. Chem. 1984. 1343: J .
Michel, Dissertation. Universitat Konstanz 1983.
[6] R. R. Schmidt, P. Zimmermann, Tefruhedron Letr. 27 (1986) 481.
171 ’H-NMR: I (250 MHz, CDCI,, TMS): 6=7.42-8.06 (m, 5 H, Bz), 5.855.96 (m. I H, CHI-CH=), 5.48-5.65 (m, 2 H , =CH-CH-OBz), 5.35 (d,
I H , H-4’, J = 2 . 7 Hz), 5.07-5.23 (m, 2H), 4.89-4.98 (m,2H). 4.45-4.53
(m, 3 H), 4.02-4.12 (m, 3 H), 3.79-3.97 (m, 4H). 3.54-3.65 (m, 2 H), 1.962.20 (m, 23H, 7Ac, =CH-CH2), 1.24-1.37 (m, 22H, I l C H > ) , 0.88 (1,
3 H , C H 4 - 4 (250 MHz, [D,]Dimethyl sulfoxide, TMS): S=7.54 (d,
I H, NH, 5=8.8 Hz), 5.49-5.57 (m, I H, =CH-CH2), 5.30-5.39 (m. 3 H,
=CH-CHOH, CH=CH), 5.16 (d, I H, OH, J=3.7 Hz), 5.12 (d, I H, OH,
J = 3 . 3 Hz),4.90(d, I H , O H , J = 5 . 5 Hz),4.84(d, I H , O H , 5 ~ 3 . 1Hz),
4.68 (very broad, 2H, ZOH), 4.58 (m, 2H, 2 0 H ) , 3.29-4.22 (m,17H).
3.02-3.09 (m, 1 H), 1.96-2.06 (m, 8 H , COCH?, 3 =CH-CHZ), 1.23-1.48
(m. 44H, 22CHz), 0.83-0.91 (2t, 6 H , 2CH,). The compounds 5 - 7 also
gave correct ‘H-NMR data.-The UV spectroscopically determined
amounts of fatty acid esters with conjugated double bonds are: < 1% for
6 and <3% for 7.
[8] Florisil (magnesium silicate), 16-30 mesh, Fluka AG; RP,,, Merck.
[9] P. LBuger, Angew. Chem. 97 (1985) 939: Angew. Chem. I n f . Ed. Engl. 24
(1985) 905.
194
0 VCH Verlagsgesellschaft mbH. 0-6940 Weinheim, 1987
2
CPh2
@
h,,,[nrn]
(in CHC
, OH
,
(Lge): 627 (4.95)
641 (5.26)
409 (3.27)
426 (4.35)
+
5% CF,CO,H)
(in CF3C0,H)
This can be readily explained with the aid of the characteristic HMO frontier orbital scheme for the alternating
structural types shown above. The scheme is characterized
by two non-bonding (n) orbitals and the weakly bonding
and antibonding molecular orbitals b, a, respectively, of
opposite but equal energies (Fig. I).
-
-
44%-
a (-0.28)
- “(0.00)
b(0.28)
3t
1
2
Fig. 1. Frontier orbital occupancy scheme for conventional triphenylmethylium ions 1 a n d their tricationic “inverse” analogues 2 in the Huckel approximation (energies in @units).
[‘I
Prof. Dr. D. Hellwinkel, DipLChem. H. Stahl, DipLChem. H. G. Gaa
Organisch-chemisches lnstitut der Universitat
Im Neuenheimer Feld 270, D-6900 Heidelberg I (FRG)
[**I This work was supported by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and by BASF AG.
0044-8249/87/0808-0794 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 26 (1987) No. 8
From the different occupancies of the frontier orbital region of the dyes of type 1 and 2 it follows that at the level
of the Huckel approximation even identical longest-wavelength electron excitations are to be expected.
If the two electrons in the weakly bonding molecular orbital b are also removed, a new chromophore-type
emerges, which-corresponding to a frontier excitation
I.OOfi-b(0.28 P)-should absorb in the UV/VIS spectrum
at a shorter wavelength than 2 [b(0.28P)-n,
641 nm], yet at a still longer wavelength than the yellow
triphenylmethylium ion 3 [1.00B-n, A,,, =432 nm].121
We have now transformed this idea into reality by replacing also the last N donor function in 2 by a carbenium
center. Thus, we allowed the key reagent 4J3) accessible
from benzophenone by reaction with 4-bromophenyllithium, to react, after bromine-lithium exchange to give 5,
with methyl chloroformate to give the trisether of the tetraalcohol 6, which yielded the tetrakis(ethy1 ether) 7 with
ethanol.
10a, X = Br
12
h max(lg&): 440 (4.97)
l o b , X = Li
1 1 , X = CPhzOMe
14
13
1. CIC0,Et
4 . X = Br; 5 , X = Li
-
-
L
'3
6 , R = H; 7. R = Et
Reaction of 7 with trifluoroacetic acid afforded exclusively the yellow trication 8, which is none other than a
spacer-coupled, and thus conjugatively separated, triple
tritylium
Only stronger acids such as sulfuric
acid or trifluoromethanesulfonic acid can liberate from 7
o r 8 the novel reddish-violet tris[4-(diphenylrnethyliumyl)phenyl]methylium ion 9, which upon dilution with trifluoroacetic acid resolvolyzes to the yellow trication 8.
h max(lg&): 469 (5.02)
Table 1. 'H-NMR data of the triphenylmethylium ions 2, 3, 8, 9 , 13, and 14
(room temperature, S values rel. TMS), prepared from the corresponding ethers [a] with the given acids quoted under "solvent". Numbering scheme:
0
y = C, COR. N; n = 1, 2, 3
Ion Solvent
3
14
2
h ,,,[nm]
R
=
CPhz
0
9
3',5'
(3",5")
7.77
7.95
7.92
8.07
CPhz
2,6
3.5
-
-
8.34
-
-
8.50
8.03 8.03
8.31
8.00 7.97
4'
(4")
30
7.80
7.95
CFJSO~H[c]
30
8.04
8.17
(8.35)
8
CF3COzD
30
7.80
7.94
8.36
7.98 8.25
9
CF;SO,H [c]
4 0
8.14
8.22
8.68
8.57 8.38
8.61 8.30 8.22
(8.84)
8
(tgc): 437 (5.45)
517 (5.45)
E t o r acid r e s i d u e
Aside from the electronic spectrum, the 500-MHz 'HNMR spectrum15] is especially informative regarding the
structure of the tetracation 9. For the p-protons of the
outer phenyl groups it shows, with 6=8.68, a chemical
shift value which lies well above the values hitherto observed for such protons in tritylium ion^['-^.'^ (Table 1).
In a comparable way, a through-conjugated trication,
the red bis[4-(diphenylmethyliumyl)phenyl]phenylmethyIium ion 13 could be synthesized and characterized via the
reaction of the difunctional key reagent 10b analogous to
5 with benzophenone to give the trisether 11 and its dissolution in acids. Like 9, the ion 13 is stable only in trifluoromethanesulfonic acid and is resolvolyzed with trifluoroacetic acid to give the yellow dication 12. In 13 it is the
p-proton of the phenyl group coupled to the central carbeAngew. Chem. I n f . Ed. Engi. 26
CF3COZH/CD2Clz
0
( l / l ) [bl
CF;COZH/CF3S0.,H/ 2 0
CDzCIl (1/0.5/4) [b]
2l.6'
(2".6")
(8.32)
CF3C02H
8
Charge
CF3C02D
13
CF3S0,H
449 (4.84)
(1987) No. 8
[a] All precursors afforded correct analytical values and 'H-NMR spectra. [b]
Referred via 6(CHICl2)=S.288 to TMS. [c] Relative to CDCI?/TMS extern.
nium function which shows a record deshielding value of
6=8.84 in the 'H-NMR spectrum (Table 1).
The tri- and tetra-cations 13 and 9, respectively, are the
first members of a series of novel, conjugated multitritylium systems of which we are presently synthesizing some
representative examples. Hitherto, only one conjugated dication of this type, the yellow 1,4-phenylenebis(diphenylmethylium) 14, was known.l8]
Received: April 13, 1987 [ Z 2195 IE]
German version: Angew. Chem. 99 (1987) 822
[I] D. Hellwinkel, H. Stahl, H. G. Gaa, R. Gottfried, Phosphorus Sul/ur I8
(1983) 121; D. Hellwinkel, H. G . Gaa, R. Gottfried, 2. Naturforsch. 8 4 1
(1986) 1045.
0 VCH Veriagsgesellschaft mbH. 0-6940 Weinheim. 1987
0044-8249/87/0808-079S $ 02.50/0
795
121 G. Olah, C. U. Pittman, Jr., M. C. R. Symons in G. A. Olah, P. von R.
Schleyer (Eds.): Carbonium Ions. Vol. I . Interscience, New York 1968, p.
153.
[3] H. Stahl, Diplomarbeif. Universitat Heidelberg 1981.
[4] Cf. also: H. Volz, Terrahedron Lerf. 1977. 4683.
[5] We thank Dr. Grosskurfh. Max-Planck-Institut fur Medizinische Forschung, Heidelberg, for recording the 'H-NMR spectrum.
[61 Cf. also: D. Hellwinkel, G . Aulmich, M. Melan, Chem. Ber. 114 (1981)
86.
[7] It has so far been impossible to obtain reproducible "C-NMR spectra.
181 0 . A. Olah, J. L. Grant, R. J. Spear, J. M. Bollinger, A. Serianz, G. Sipos,
J. Am. Chem. SOC.98 (1976) 2501; H. Hart, T. Sulzberg, R. R. Rafos, ibid.
85 (1963) 1800; H. Volz, M. J. Volz d e Lecea, Tefrahedron Leu. 1964,
1871.
derivatives by demethylation with Me3SiI. Reaction of the
phenols with the dioxetane-substituted chloroformate 2 in
the presence of stoichiometric amounts of triethylamine in
0
0
M e Me
I1
C L - C - O - C H ~ + +*M ~
ArylOH
EtJN
,
> AvlO-C-0-CHZ
0-0
0-0
2
3
0
0
II
II
AryLO-C-O-CHZ-C-CH3
A Psoralen-SubstitutedDioxetane as
DNA Intercalator for Photogenotoxic Studies**
H~C-C-CHS
I1
0
By Waldemar Adam,* Axel Beinhauer, Roland Fischer,
and Hermann Hauer
The phototherapeutic action of psoralen 1, a linearly
fused furocoumarin composed of benzofuran and coumar-
4
c: A r y l =
0
Table I. Activation parameters and excitation yields for the thermal decomposition of dioxetanes 3a-c and 5.
5
3b
3a
~~~~~
[*] Prof. Dr. W. Adam, DipLChem. A. Beinhauer, R. Fischer,
Dr. H. Hauer
lnstitut fur Organische Chemie der Universitat
Am Hubland, D-8700 Wurzburg (FRG)
This work was supported by the Deutsche Forschungsgemeinschaft
(Sonderforschungsbereich 172: "Molekulare Mechanismen Kanzerogener Primarveranderungen"), the Fritz-Thyssen-Stiftung, and the
Fonds der Chemischen Industrie.
796
0 V C H VerlagsgesellschaJi mbH, 0-6940 Weinheim. 1987
~
AS* [cal rnol-'K-']
3c
5 la1
~~
AH * [kcal/mol]
+
in, in psoriasis rests o n its photochemical [2 21 cycloaddition to DNA under UVA irradiation (300-400 nm)."] These
polycyclic heteroaromatic molecules intercalate into the
DNA ladder and on excitation by UV radiation they cycloadd at the a-pyrone and/or furan double bonds to
proximate pyrimidine bases (preferably thymine) with formation of four-membered rings. Recently we were able to
show[21that 1,2-dioxetanes (chemical sources for electronically excited statesI3]) cause photochemical damage to
DNA. While in isolated DNA dioxetanes induce photochemical cycloaddition, in cellular DNA their photogenotoxic action mainly derives from radical-type damage, e.g.
strand breaks.I2'
The aim of this study was to bind dioxetanes chemically
to psoralen, with the intention that the intercalative ability
of such furocoumarins would help to transport the psoralen-bound dioxetane to the DNA. Subsequent thermal
decomposition of the dioxetane would then lead to electronically excited psoralen, which should cycloadd to the
DNA.
We report here on the successful synthesis, by carbonate
linking,'4' of the first psoralen-substituted dioxetanes 3a-c
and on their activation parameters and excitation yields
(see Table 1).
The benzofuran- and the coumarin-substituted dioxetanes 3a and 3b, respectively, served as model substances
in the synthesis of the psoralen-substituted dioxetane 3c.
These three dioxetanes will be used as model compounds
in future photobiological experiments. The corresponding
phenols were prepared in 43-58% yields from the methoxy
[**I
4
+
24.5k0.4
-3.6k1.3
AG* [kcal/mol] [b]
23.5t0.3
-6.5k0.7
23.720.4
-5.811.2
23.7T0.3
-5.3k0.9
25.6f0.40
25520.3
25.5k0.4
25.320.3
10" 0
'[E/mol]
0.9 f0.1
723
6f2
l l f 5
10' cDT [E/mol]
15f3
1422
4T 1
14f3
[a] Data taken from Ref. [Z). (bl Calculated from AH' and ASc at 310 K
dichloromethane at 0°C led to the dioxetanes 3a-c. These
were purified by chromatography on silica gel at low temperature (-30°C). Thermolysis (ca. 75°C) of 3a-c afforded quantitatively the ketocarbonates 4a-c with chemiluminescence. All the new compounds 3 and 4 were completely characterized (see Table 2['').
The activation parameters of the dioxetanes 3a-c (Table
1) were determined photometrically by monitoring the
chemiluminescence emission under isothermal conditions.[61Within the limits of error, the dioxetanes 3 exhibit
almost the same thermal stability, which hardly differs
from that of dioxetane 2 and its precursor, the hydroxymethyl(trimethyl)-1,2-dioxetane 5 .12".71
Me Me
~e
HOCH,+-
0-0
5
The excitation yields of the dioxetanes 3a-c (Table 1)
were determined photometrically using Stern-Volmer kinetics (9,IO-diphenylanthracenefor singlet yields and 9,lOdibromoanthracene for triplet yields)."' In the case of 3ac, as in the case of 5, the triplet excited carbonyl products
predominate by a factor of 100. While 3a, b furnish approximately the same triplet yields as 5 , that of the psoral-
0570-0833/87/0808-0796 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 26 (1987) No. 8
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