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Benzobis(thiadiazole)s Containing Hypervalent Sulfur Atoms Novel Heterocycles with High Electron Affinity and Short Intermolecular Contacts between Heteroatoms.

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2 was adjusted to pH 7.1 with 2,6-lutidine and Ni" is added, no
substantial decrease in IFwas observed, even after the addition
of one or more equivalents of metal ion (Fig. 3). When Cu" was
added to the same solution, IF decreased linearly and reached
zero on addition of one equivalent of the metal ion (Fig. 3 ) .
Until now anthracene-based fluorescent sensors for metal
ions have been known primarily for alkali and alkaline-earth
metal ions. Typically the uncomplexed sensor does not fluorescence and the binding of the metal to the receptor results in
fluoresce; this switching mechanism is triggered by photoinduced electron transfer."] Compound 2 is the prototype of a
new family of pH-sensitive anthracene-based fluorescent sensors for transition metal ions. Here the uncomplexed sensor
fluoresces, and the interaction with the 3d metal ion leads to
fluorescence quenching; this switching mechanism is triggered
by energy transfer. Sensor selectivity towards transition metal
ions can be modified by changing the structural features of the
chelating unit: this unit can be cyclic or noncyclic, the number
and arrangement of amide groups can be changed, and other
heteroatoms can be included. We are currently designing and
testing these types of sensors.
Experinwntul Procedure
Benzobis(thiadiazo1e)s Containing Hypervalent
Sulfur Atoms: Novel Heterocycles with High
Electron Affinity and Short Intermolecular
Contacts between Heteroatoms**
Katsuhiko Ono, Shoji Tanaka, and Yoshiro
Heterocycles containing hypervalent sulfur atoms have attracted considerable attention owing to their unique electronic
structures and reactivities.['I 1,2,5-Thiadiazole rings containing
a tetravalent sulfur atom are more stable than the related thiophene rings found in the stable pyrazine derivative 1[*] and the
stable bicyclic compound 2.[31Compound 1 is a strong electron
and forms a ribbonlike structure by short intermolecular contacts between the hypervalent S atoms and the N
atoms. In this context heterocycle 3a is expected to have a high
electron affinity and form a unique molecular network. This
compound resembles the framework of bis([l,2,5]thiadiazolo)tetracyanoquinodimethane (BTDA-TCNQ 4). which is an electron acceptor in organic metals and forms a sheetlike network
through short S . . . N=C contacts.[*] However, 5, which was
prepared from 4, is its only reported derivative.16] We have now
synthesized the i.2,d4-benzobis(thiadiazole)derivatives 3 b and
I : Diethyl malonate (0.75 g, 4.72 mmol) and 9-chloromethylanthracene (0.91 g.
4.03 mmol) were added to a solution of sodium ethoxide in anhydrous ethanol
(0.1 1 g. 4.72 mmol of Na in 20 mL of EtOH). The solution was heated at reflux for
1X h. The NaCl precipitate formed during the reaction was filtered off and the
solvent evaporated in vacuo. The residue was redissolved in diethyl ether. and
yellow crystals were obtained by slow evaporation. Yield: 68%. Correct C.H,N
analysis for C?,H,,O,
2 : Ethylenediamine (30 mL, freshly distilled over CaO) and 1 (0.5 g, 1.43 mmol)
were stirred at room temperature under nitrogen for 7 d. Excess ethylenediamine
was disMed off under reduced pressure. Treatment of the yellow residue with
diethyl ether gave a pale yellow precipitate. which was filtered offand recrystallized
fromethanol. Yield 74%. M.P. ?05--208 C. MS (7OeV)'m!z37X(Mt. 73%). 349
( [ M CHNH2]'. 5 2 % ) . 191 (C,,H,CHi. 100%). Correct C.H.N analysis for
3b: R = Br
3C: R = Ph
Received: May 13, 1994 [Z 6932 IE]
German version: A n g i w . Chrm. 1994. 106. 2051
R. A. Bissell. A. P. de Silva. H. Q. N Gunaratne. P. L. M. Lynch, G. E. M.
Maguire. C. P. McCoy, K . R. A. S. Sandanayake. T o p . Curr. Chrm. 1993. 168,
V. Goulle. A. Harriman, J.-M. Lehn,J. Chm7. Soc. Chrm. Commun. 1993. 1034.
R. A . Blssell. A . P. de Silva. H. Q. N . Gunaratne, P. L. M. Lynch. G. E. M.
Maguire. K. R A. S. Sandanayake, Clieni. Sot. Rev. 1992. 187.
A. P. de Silva. R. A . D. D. Rupasinghe, J. Chem. Soc. Cliem. Commur7. 1986,
I 70').
A . P de Silva, S. A. de Silva, J. Cllmm. Sor. Cherv. Commun. 1986, 1709.
E. U. Akkaqa. M. E. Huston, A. W. Crarntk. J. Ani. Chrm. Soc. 1990, 11-7,
M. Kodama. E Kimura, J Chem. Sor. Dalton Trans. 1979, 325.
D. W. Margerum. G. R . Dukes in Metal Ions in BiologiculSj~tems,Vol. I (Ed.
H. Sigel). Dckker, New York, 1974, p. 157. an references therein.
P. Suppan. Chpmi.sfrvand Lifiht, The Royal Society of Chemistry, Cambridge,
1994. p. 66.
V. Balrani. F. Scandola, Suprun?oleculur Photochemistrj,, Horwood. London.
1991. p. 71
L. Fabbrizri. A. Perotti, A. Poggi, lnorg. Chem. 1983, 22. 1411.
1.Fabbrizri. T. A . Kaden. A. Perotti, B. Seghi, L. Siegfried. /norg. Chrm. 1986.
5 : R = H, C(CH&CN
6b: R = Br
6~ : R = Ph
7a : R = Br
7b : R = Ph
8a : R = Br
8b : R = Ph
Prof. Dr. Y Yamashita. K . Ono. Dr. S. Tanaka
Department of Structural Molecular Science
The Graduate University for Advanced Studies
and Institute for Molecular Science
Myodaiji. Okazaki 444 (Japan)
Telefax: Int. code (564)54-2254
Angtw. Clwni, /nt.
Ed. EngI. 1994. 33. N o . 19
This work was supported by research fellowships from the Japan Society for
the Promotion of Science for Young Scientists. We thank Prof. Dr. K. Tdnaka,
Institute for Molecular Science. for conducting the X-ray crystallographic
study, and Prof. Dr. S. Hirdyama. Kyoto Institute of Technology. for the
measurement of the fluorescence spectrum of 3c.
VCH Verlufisfie.tell.sclia~tmhH, 0-69451 Weinheim, 1994
0570-0833iY4,'1919-1Y77 d 10.00+ .25/U
3c and the analogous selenadiazoles 6b and 6c.[*]We report
here their preparation and characterization, and the crystal
structure of 3 b.
Reduction of dinitrobenzothiadiazole 7aC7]with iron dust in
acetic acid gave diamine 8a.['] Heterocycle 3b was prepared in
74% yield by reaction of diamine 8 a with thionyl chloride in
pyridine at room temperature. The analogous heterocycle 6b
was obtained in 40 % yield from diamine 8a and selenium dioxide. The palladium-catalyzed coupling ([PdCl,(PPh,),]) of bromide 7a with phenyltributyl stannane"] in tetrahydrofuran afforded 7 b, which was reduced with iron dust to give diamine 8 b.
Heterocycle 3 c was prepared in 95 YO yield by reaction of diamine 8 b with N-thionylaniline and trimethylsilyl chloride in
pyridine at 80 'C. The selenium compound 6 c was obtained in
82 % yield from the diamine 8 b and selenium dioxide. These
heterocycles were purified by sublimation under reduced pressure and isolated as deep red crystals for 3 b (decomp > 280 "C),
purple prisms for 3c (decomp 310-31 1 "C), purple crystals for
6b (decomp > 28O"C), and blue crystals for 6c (decomp 367371 C). The absorption maxima of 3b, c and 6b, c are listed in
Table 1 and compared with that of benzobis(thiadiazo1e) 9,
whose thiadiazole ring can be represented by a standard Kekule
structure. The red shifts of 6b, c from 3b, c are regarded as a
Table 1 . Absorption maxima and fluorescence emission maxima of heterocycles
3. 6, and 9 [a]
i,,,Inml Og d
I,, [nml
524 (3 64)
558 (3.99)
609 ( b l )
625 (4 01)
283 (4.57)
electron-withdrawing bromo groups at 4- and 8-positions further increase the reduction potentials (cf. 3 b and 3c). The fact
that the Kekule-type isomer 9 is a weaker acceptor (Table 2)
shows that the high electron affinity of 3 and 6 is attributable to
the 14n: electron system containing a tetravalent sulfur atom,
which generates more stable Kekule-type thiadiazole moieties
upon accepting an electron.
Table 2. Reduction potentials (in V ) of heterocycles 3, 6 c . and 9 [a].
-0 35
- 1.45
- 1.30
- 1.21
0 68
[a] 0.1 M nBu,NC10, in CH,C12. Pt electrode. scan rate 100 mVs-', potentials vs.
standard calomel electrode (SCE)
A single crystal of 3 b obtained by recrystallization from benzonitrile was selected for X-ray structural analysis." 2J In the
crystal the molecule is planar and has Ci symmetry (Fig. 2). The
S-N bond lengths (given in Fig. 2) are shorter than those of 9
(1.615 and 1.620 A),[131and the N - C bond lengths longer (for
9, 1.325 and 1.337 A). The bond lengths in the thiadiazole rings
are similar to those in the pyrazine derivative 1 (S-N 1.597 and
1.609 A, N - C 1.347 and 1.370 A).['] Although the molecule is
uniformly stacked along the c axis, the stacking shown in Figure 3 a indicates less effective interactions between the HOMO
and the LUMO (Fig. 1 ) .
[a] I n CH,CI,. [b] Not obtained because of its low solubility
polar effect caused by the selenium atom. We thought that introduction of substituents in the 4- and 8-positions in 3 and 6
(3 a/6 a + 3 b, c/6 b, c) would underscore this effect, since these
positions have larger atomic orbital coefficients in the HOMO
and the LUMO (Fig. l).[lol
+ 0.476
- 0.019
Fig. 2. Molecular structure of 3 b with bond lengths
[A] (ORTEP).
Fig. 1. HOMO. LUMO, and charge distribution of 3 a calculated by the MNDOPM3 method
The cyclic voltammograms (CV) of 3b,c and 6 c in
dichloromethane showed two reversible one-electron redox
waves." ' I The half-wave reduction potentials are given in
Table 2. The first reduction potentials of these heterocycles are
comparable to that of p-benzoquinone ( E = - 0.46 V). The
Only one of the possible resonance forms I S shown for each compound. For
6 the contribution of the structure containing a tetravalent Se atom is small.
V C H VerluyJgewNrchufr mhH 0-69451 Wernheim 1994
The crystal structure is composed of a set of two ribbon-type
columns which extend in the [0 1 I] and [0 1 - I] directions and
are characterized by short intermolecular S . . N and N . . . N
contacts (Fig. 3b). These columns interact with each other
through short B r . . - N contacts to form a network. The distances of the relevant contacts, S . . . N, N . . . N, and Br . . . N, are
significantly smaller than the sum of the van der Waals radii
(3.3.5,3.10, and 3.40 A). According to the net atomic charges of
3a calculated by the MNDO-PM3 method, the hypervalent S
atoms have significant positive charge and the N atoms significant negative charge (Fig. 1). Thus, the S . . .N interactions are
attributed to an electrostatic effect, which seems to induce dense
= 2.58 g ~ m - ~ ) .
packing in the crystal (pCalcd
0570-0833/9411919-l978$ 1 0 OU+ 2510
Angen Chem In! Ed EngI 1994, 33, IVO 19
56. 78; d) A. Tsubouchi, N. MatsUmura, H. Inoue. J C'/iem. S i r . Chrm. Cornmun. 1991, 520.
[2] Y. Yamashita, K. Saito. T. Sumki, C. Kabuto. T. Mukai. T.Miyashi. Angcw.
Chern. 1988. 100, 428. Angen. Chem. hi.Ed. Eng/ 1988. 27, 414.
[3] a) A. P. Komin, R. W Street, M. Carmack, J. Orx. C/wrn. 1975.40. 2749: b) J.
Kane. R. Schaeffer. C'rmr. Sfruct. Commun. 1981. 10. 1403.
[4] Half-wave reduction potentials of 1: E , = +0.10 V. E, = - 0.82 V vs. SCE:
measured with a Pt electrode in acetonitrile with 0.1 M Et,NCIO,, $can rate
1 0 0 m V s - ' [2].
[5] T. Suruki. H. Fujii. Y Yamashita, C. Kabuto. S. Tanaka, M. Harasawa. T.
Mukai, T. Miyashi. J A m . Chmt. Soc. 1992, 114, 3034.
[6] Y. YamdShltd, 7.Suruki. T. Mukai. J. Chem. Soc. C/rmi. Cornniun 1987, 11x4.
[7] T. Uno, K. Takagl, M. Tomoeda. Clrem. Phurni. Bull. 1980. 2X. 1909.
[XI Y. Tsubata. T. Suzuki. Y. Yamashita, T. Mukai. T. Miyashi. H r t e r o c w l c , 1992,
33, 337.
[9] J. L. Wardell, S. Ahmed, J. Orgunomel. Chern. 1974. 78, 3Y5.
[lo] Calculated by the MNDO-PM3 method, MOPAC program. J. J. P. Stewart. J.
Comput. Chem. 1989, 10, 209, 221.
(111 The CV of 6b was not obtained because of its low solubility.
[12] X-ray structure data for 3 b: C,Br,N,S,, M = 352.04. monoclinic. space group
P 2 , ; n . u =15.569(1),
h =7.3990(4). c = 3.9405(3)A. p = 90.192(4) ,
1.'= 453.92(5) A'. Z = 2, pLrlcd
= 2.58 g ~ m - ~F(OO0)
= 332, p(CuK,) =
153,25cm-'.A totalof1015 unlquedatafor2Hm,, =140 wascollectedonan
Enraf-Nonius CAD4 diffractometer (Cu,, radiation. i. = 1.5418 A.graphite
mono chroma tor^ w-20-scan) at 296 K. The structure was solved by Patterson
methods and refined by full-matrix least-squares analysis giving values of
R = 0.024, R, = 0.030, max.:min. residual electron density 0.37:-0.39 e k '
for 859 reflections with F, > 3 u E . All calculations were performed using the
teXsan programs. Further details of the cryztal structure investigation may he
obtained from the E'achinformationsrentrum Karlsruhe, D-76344 EggensteinLeopoldshafen (FRG). on quoting the depository number CSD-S83'M.
[13] A. Gieren, H . Betr, T. Hiibner. V. Lamm, R. Neidlein, D. Droste. %. Nulirrforsch. B 1984. 39, 485.
1141 'Details will be reported elsewhere.
3.06 A
Fig. 3. Crystal structure of 3b: a) stacking. b) ribbonlike network.
Stereoselective Intramolecular Alkylation
of Glycosylimides to Highly Functionalized
Bicyclic 2,5-Azepanediones and Heterotricyclic
I5.3.1.02 6]undecanamides**
Carsten Endres Sowa and Joachim Thiem*
MNDO-PM3 calculations"01 for 3a and 6 a also show that
the energy levels of the HOMOS ( - 8.73 eV for 3a and 6a) are
higher than that of 9 ( - 9.94 eV), and that the energy levels of
the LUMOs ( - 3.21 eV for 3a and -3.30 eV for 6 4 are lower
than that of 9 ( - 1.95 eV). These results are supported by the
longer absorption maxima and the higher electron affinities of
3 and 6. Thus, the electron properties of the heterocycles containing the hypervalent sulfur atoms are fairly different from
those of the Kekule-type isomer. On the other hand, substitution of a sulfur atom by a selenium atom little affects the
HOMO and the L U M O of the 1 4 ~electron
Heterocycles 3 and 6 display fluorescence emission spectra,
which have broad maxima (Table I), upon photoexcitation in
dichloromethane at room t e m p e r a t ~ r e . ~Since
' ~ ] 3 and 6 have
high electron affinities, their photochemical behavior is of interest and currently under study.
Received: April 29,19Y4 [Z 6880 IE]
German version: Angew. Cliern. 1994, 106, 2030
[ l ] a) M P. C'ava, M. V. Lakshmikantham in Coniprehmsire H e t e r o c y / k Cliem;.~tr,v,W. 4 (Eds.: C . W. Bird. G. W. H . Cheesemdn), Pergamon, New York,
1984. p. 1037. b) C. A. Ramsden in Comprehensive Heferocyclrc Chrrnisrrv,
& I / . 6 (Ed.: K.T. Potts). Pergamon, New York. 1984, p. 1027; c ) A Ishii, J.
Nakayama, J. Kazami, Y. Ida, T. Nakamura, M. Hoshino, J. 0r.q. Chem. 1991,
Arigeii.. ('/ieni. Inf. Cd. Engl. 1994. 33. N o . 1Y
N-Iodosuccinimide (NIS) is an effective and established
reagent for the stereoselective glycosylation of glycals."] With
secondary alcohols like, for example, cholesterol, the corresponding N-glycosylated succinimides could frequently be isolated as a by-product in substantial yields.I2. 31 In such cases, the
succinimide anion apparently competes with weak nucleophiles
to attack the intermediate iodonium ion. When no other nucleophiles or moisture is present and light is excluded. the stereoselective addition of NIS to the enol ether function of several
glycals occurs with excellent yields.[41The iodine substituent can
always be quantitatively removed with Bu,SnH/AIBN to give
This very simple preparative procedure and the high total yield is the motive for investigating the use of such glycosylimides in synthesis.
Kanaoka et al. photochemically converted N-alkylsuccinimides in a Norrish type I1 reaction to simple alkylated d a c tams.15361 In this way, N-cyclohexylsuccinimide,for example,
was transformed in rng amounts into the enantiomeric mixture
of 5,6-(perhydrobenzo)-4-oxo-~-lactam,
a bicyclic 2.5-azepanedione. In this reaction the cc-position to the imide in the alkyl
[*] Prof. Dr. J. Thiem, DipLChem. C . E. Sowa
Institute fur Organische Chemie der Universitiit
Martin-Luther-King-Platr 6. D-20146 Hamburg (FRG)
Telefdx: Int. code +(40) 4123-4325
[**I This work was supported by the Fonds der Chemischen Industrie.
cc; VCH Vc.rlugs~cse/lschiiftm h H , D-69451 Wcinhrirn. 1994
OS70-OK33!94:1919-1Y79 Y lfi.OO+ .25jO
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short, high, sulfur, contact, heteroatoms, electro, intermolecular, containing, benzobis, atom, thiadiazole, hypervalent, novem, heterocyclic, affinity
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