close

Вход

Забыли?

вход по аккаунту

?

Dipyrrolo [2-a 2 l-c]quinoxalines A Novel Heterocyclic System.

код для вставкиСкачать
Zn-C distances and the differing deviations of the hydrogen atoms from the allyl plane, the meso C-atoms are
practically equidistant from the two Zn atoms. (Difference
0.013 A.) The Zn-C2 bond lengths are very long for a ZnC n-bonding and can possibly be explained in terms of a
very unsymmetric (distorted) n-complexation of the C2-C3
bond, caused by the simultaneous o-bonding of C1 to a
further Zn atom, o r a frozen-in dynamic process, in the
course of which C1 and C 3 are each alternately n- and ocoordinated. The Zn atoms themselves lie on twofold axes
of rotation and are each surrounded pseudotetrahedrally
by four methylallyl ligands. The overall result is a threedimensional polymeric structure.
In the case of 3 and 4 the terminal C-atoms of the allyl
moiety absorb at 6 = 5 2 and 55, respectively, in the solidstate "C-NMR spectrum. The spectra of 3 and 4 in T H F
solutions already show signals characteristic for an q'-allyl
structure at 200 K, whereas no changes in the "C-chemical
shifts and signal halfwidths are observed u p to 180 K
(Bo= 7.0 T) in the solid state spectrum of 3. Since it is unreasonable to assume that the barrier for a TI-o ally1 rearrangement (in 3 and 4 compared to 2) is considerably
lowered by the methyl group on C2 or the CI-substituents
on Zn, we conclude, in agreement with IR/Raman spectroscopic results,12' that in the absence of donors the ally1
groups of 3 and 4 are symmetrically q3-complexed to zinc
in the solid state.
The results show that in the solid state the simple allyl
compounds of zinc can be of quite different structure types
A, B, or C,depending upon the alkyl substituent attached
to the allyl moiety and the ligand attached to the metal.
'
M
A
Me
M
B
<
I
C
The differences in the ground state energies for A, B and
C are obviously only small, so that upon dissolution in donor solvents exclusively the structure type A is found.
Moreover, it is clear in the case of 2 that a classification of
the allyl structure type merely on the position of the C = C
valence vibrations is problematic.
Received: August 5, 1987 [Z 2388 IE]
German version: Angew. Chem. 99 (1987) 1303
[I] a) G. Wilke, B. BogdanoviC, P. Hardt, P. Heimbach, W. Keim, M. Kroner, W. Oberkirch, K. Tanaka, E. Steinriicke, D. Walter, H. Zimmermann,
Angew. Chem. 78 (1966) 157; Angew. Chem. In!. Ed. Engl. 5 (1966) 151;
b) K. Vrieze in L. M. Jackman, F. A. Cotton (Eds.): Dynamic Nuclear
Magnetic Resonance Spectroscopy, Academic Press, New York 1975, p.
441; c) R. Benn, A. Rufinska, Organometallics 4 (1985) 221; d) M.
Schlosser, M. Stahle, Angew. Chem. 94 (1982) 142; Angew. Chem. Ini.
Ed. Engl. 21 (1982) 145; Angew. Chem. Suppl. 1982. 198; e) G . Fraenkel,
H. F. Halasa, V. Mockel, R. Stumpe, D. Tate, J . Org. Chem. 50 (1985)
4563; R. T. McDonald, S. Bywater, Organometallics 5 (1986) 1529; f) W.
R. Winchester, W. Bauer, P. von R. Schleyer, J Chem. SOC.Chem. Commun. 1987. 117, and references cited therein.
121 E. G. Hoffmann, H. Nehl, H. Lehmkuhl, K. Seevogel, W. Stempfle,
Chem. Ber. 117 (1985) 1364, and references cited therein.
[3] a ) H. Koster, E. Weiss, Chem. Ber. 115 (1982) 3422; b) M. Marsch, K.
Harms, W. Massa, G. Boche, Angew. Chem. 99 (1987) 706; Angew.
Chem. Int. Ed. Engl. 26 (1987) 696; c) U. Schiirmann, E. Weiss, H. Dietrich, W. Mahdi, J . Organomet. Chem. 322 (1987) 299, and references
cited therein.
[4] T. Clark, G. Rhode, P. von R. Schleyer, Organometallics 2 (1983) 1344.
151 a) C. S. Yannoni, Acc. Chem. Res. 15 (1982) 201; b) J. R. Lyerla, C. S.
Yannoni, C. A. Fyfe, ibid. I 5 (1982) 208: c) E. Oldfield, J. R. Kirkpatrik,
Science 227 (1985) 1537.
1280
0 VCH Verlagsgesellschaji mbH, 0-6940 Weinheim. 1987
161 a) R. R. Ernst, G. Bodenhausen, A. Wokaun: Principles ofNuclear Magnetic Rerononce in One and Two Dimensions. Clarendon Press, Oxford
1987; b) for the two-dimensional CP-MAS "C-NMR exchange spectroscopy of organometallic compounds cf. R. Benn, H. Grondey, R. Nolte,
G. Erker, Organometallics. in press.
171 We have observed a similarly strong deshielding of C2 in the solid-state
"C-NMR spectra of allylmagnesium halides. In contrast, no significant
shift changes are observed between the solution and the solid-state spectrum for the central allyl carbon atom in [(q'-allyl)4Mo]. [(q3-2-methylallyl),Pd] o r in ether-free [(q3-allyl)Li]. We tentatively attribute the strong
deshielding of C 2 in the CP-MAS NMR spectra (compared to in solution) to a change in the allyl-metal bonding in the solid state, as has
been found for example in the case of 2 .
[8] The IR and Raman spectra of solid 2 and 3 [2] ( 2 : IR 1540. Raman
1550; 3 : IR 1520; Raman 1535 c m - ' ) have been interpreted as being
consistent with symmetrically delocalized $bound allyl groups. In the
case of 2, the CP-MAS "C-NMR spectra clearly contradict this interpretation, whereas in the case of 3 they support it.
[9] Regarding the intramolecular zinc/CC double bond interaction cf. also:
A. Haaland, H. Lehmkuhl, H. Nehl, Acta CIwm Scand. A 3 8 (1984)
547.
[lo] Further detalls of the crystal structure investigatlon are available o n request from the Fachinformationszentrum Energie, Physik, Mathematik
GmbH, D-7514 Eggenstein-Leopoldshafen2 (FRG), on quoting the depository number CSD-52617, the names of the authors, and the journal
citation.
Dipyrrolo[l,Za :2',1'-c]quinoxalines:
A Novel Heterocyclic System**
By Gerd Kaupp,* Heike Voss, and Herbert Frey
Dedicated to Professor UIrich Schollkopf on the occasion
of his 60th birthday
Whereas open-chain nitrones are highly reactive partners for 1,3-dipolar cycloadditions to di- and tetrahydro
oxazoIes,['] no cycloadditions have thus far been reported
for the quinoxaline dioxides, which are currently the subject of intensive studies because of their wide-ranging biological a c t i ~ i t i e s . ' ~In
. ~ the
] reaction of 2,3-dimethylquinoxaline dioxides 1 with phenylpropiolate 2 we have now
found a convenient method for the synthesis of the first
derivatives of the new heterocycle dipyrrolo[ 1,2-a :2', 1'-c]q~inoxaline.~~]
Reaction of 1lS1with an excess of 2 for 3 d at 115°C
(Scheme 1) leads to elimination of water and regioselective
formation of 3 (35% 3a, 20% 3 b ; no regioisomers). The
structure of the reaction product was derived from the 'HNMR spectra of 3 and the derivative 4, which was obtained by saponification and decarboxylation of 3a. I n
particular the singlet at 6=6.78 (Avl,,=2 Hz) in the spectrum of 4 is reconcilable only with a 2,4-relationship of the
H atoms of the pyrrole ring.161By-products of the reaction
include, inter alia, dimethyl-l-phenylnaphthalene-2,3-dicarboxylate, the dimer of 2 which presumably is formed
by [4+2]-cycloaddition in conjunction with a 1,3 H-shift.
As expected this novel mode of reaction (eliminating cycloaddition) is not restricted to 2,3-dimethylquinoxaline
dioxides. Thus, the monoxide 5 also reacts regioselectively
with 2 to give 6 (1 15"C, 4 d, 44%; no regioisomers).
The yellow compounds 3 and 4 containing the new heterocyclic ring system[41are stable and exhibit the expected
structured UV/VIS spectra, the molecular ions as the most
intense signals in the mass spectra, and unequivocally as[*] Prof. Dr. G. Kaupp, DipLChem. H. Voss, Dr. H. Frey
Fachbereich Chemie-Organische Chemie I-der Universitat
Postfach 2503, D-2900 Oldenburg (FRG)
[**I This work was supported by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and the Bundesministerium fur Forschung und Technologie (Project 10 IVS 325).
0570-0833/87/1212-1280 $ 02.50/0
Angew. Chem. Inr. Ed. Engl. 26 (1987) No. I2
of this condensation reaction involving ring closure is
presently under investigation.
0
t
+ 2
/I/
- 2
~
c6H5
0
1
2
7
3 k . b
J.
a.
b,
R
R
a,
= H;
b , R = CH,
Experimental
= H;
= CH,
C6H5
Scheme I . a) Benzyltrimethylammonium hydroxide. b) Thermal decarboxylation.
signable N M R signals (Table 1). They are potential partners for the construction of highly condensed heterocycles
and promise useful biological activities, as d o numerous
alkaloids of the indolizine type.
0
t
C02CH3
+
Ill
C6H5
5
R
C6H5
2
6
Table I. Important physical and spectroscopic data of the compounds 3, 4,
and 6 171. UV spectra in CH2Cl2,80-MHz 'H-NMR and 20-MHz "C-NMR
spectra in CDCI,; 70 eV mass spectra.
3a: m.p. 243°C; UV: l,,,(lg&)=375 (4.13), 358 (4.19), 345 (sh, 4.10), 307 (sh,
4.33), 300 (4.39, 272 nm (4.57).--'H-NMR: 6=7.65-7.2 (14H), 6.72 (2H, s),
3.79 (6H. s).-"C-NMR: 6=162.6 (C=O), 138.1, 134.5, 129.5, 129.5, 128.4,
127.9, 127.7, 127.7, 126.7, 124.9, 120.4, 117.2, 105.3, 51.6 (CH,).-MS: m / z
474 ( M a ,
lOO%), 443 (7), 416 (32), 358 (28), 355 (22), 320 (5), 289 (9), 279 (3),
237 (4), 221 (9), 177 (16)
3b: m.p. 151°C; UV: A,,,(lg&)=371 (sh, 4.25), 357 (4.32), 345 (sh, 4.22), 307
(sh, 4.41), 301.5 (4.43), 269 nm (4.68).-'H-NMR: 6=7.6-7.3 (12H), 6.71
(2H, s), 3.78 (6H, s ) , 2.34 (6H, s).-MS: m/z 502 (M", 100%),472 (2), 444(9),
443 ( I ) , 384 (6). 383 (9), 251 (4), 236 (l), 235 (2), 184 (4)
4 : m.p. 222OC; UV: l,,,(Ig&)=313.5 (l,6l), 287.5 (3.601, 264 (4.63), 249 nm
(sh, 4.52).-'H-NMR: 6=7.7-7.15 (16H), 6.78 (2H, s).-MS: m / z 358 (Me,
100°/o), 332 ( I ) , 330 (3). 328 (2), 282 (I), 280 (3). 254 (3), 179 (12). 178 (4), 140
(I), 102 (1),77 (2)
6 : m.p. 118°C: UV: d,,,(lg&)=334 (3.96), 345 (sh, 3.90), 265 nm (4.54).'H-NMR: 6=7.95-7.25 (9H), 6.85 (1 H, s), 3.79 (3H, s), 2.67 (3H, s).-"CNMR: 6 = 163.6 (C=O), 152.6, 136.5, 134.0, 133.6, 129.1, 128.5, 128.5, 127.8,
127.8, 127.4, 127.1, 126.7, 126.5, 125.2, 118.0, 116.0, 106.2, 51.8 (CH,), 21.4
(CH3).-MS: m / z 316 ( M " , 100°/o), 285 (42), 258 (61), 257 ( l l ) , 242 (5), 158
(3), 128 (8). 77 (1 1)
Since compounds of the types 1 and 5 are accessible in
a large variety of ways the reactions presented here may
prove to be preparatively very productive. Care should b e
taken, however, that the heterocyclic a-alkyl N-oxides are
not too nucleophilic, otherwise predominantly alternative
products like 7l7](from 2,6-dimethyl- or 2,4,6-trimethylpyridine N-oxide and 2) are formed, in which 2 is incorporated in reversed orientation.[*' The scope and mechanism
Angew. Chem. I n t . Ed. Engl. 26 (1987) No. I2
3a: A mixture of l a (1.0 g, 5.3 mmol) and 2 (8.5 g, 53 mmol) was heated in a
flask fitted with a condenser for 3 d at 115°C; the color of the liquid changed
from yellow through green and red to greenish black. On cooling, 3a crystallized out; it was recrystallized from 2-propanol: 0.77 g, m.p. 243°C. From the
mother liquor, a further 0.IOg of 3a (total yield 35%) could be separated
from 2, its dimer, a green compound (80 mg, M0=618), by-products, 2,3dimethylquinoxaline monoxide (24%), and 2,3-dimethylquinoxaline (24%) by
chromatography on silica gel with dichloromethane and ethyl acetate.
Received: June 9, 1987;
revised: September 10, 1987 [Z 2289 IE]
German version: Angew. Chem. 99 (1987) 1327
11) See for example J. Hamer, A. Mahaluso, Chem. Rev. 64 (1964) 473: R.
Huisgen, A. Eckell, Tetrahedron Lett. 1960. 5 ; R. Huisgen, Angew Chem.
75 (1963) 604, 742; Angew. Chem. Int. Ed. Engl. 2 (1963) 565, 633.
[2] Numerous derivatives have trade names (Mecadox, Quindoxin, Grofas,
Carbadox, Dioxidine, etc.); they are employed, inter alia, as growth-promoting food additives, bactericides (hair and body conditioners), fungicides, and herbicides as well as medicaments (drugs).
[3] A contrary report (M. Ungureanu, 1. Druta, I. Zugravescu, An. Stiint,
Uniu. " A l . I . Cuza" Iasi Sect. 1C 20 (1974) 29; Chem. Abstr. 82 (1974)
125351 q) could not be duplicated; the compounds formulated therein
should not be stable but undergo prototropic rearrangements (see, for example, M. J. Haddadin, M A. Atfah, J . Org. Chem. 47 (1982) 1772).
[4] CAS Registry number of the parent compound: 37694-85-2; possible substituted tetrahydro derivatives have not been constitutionally confirmed:
R. M. Acheson, M. S . Verlander, J . Chem. Snc. Perkrn Trans. I 1972,
1577; ibid. 1974. 430.
151 J. K. Landquist, J . Chem. Snc. 1953. 2816.
161 Cf. M. Hesse, H. Meier, B. Zeeh: Spektroskopische Merhnden in der Organischen Chemie, 2nd edit., Thieme, Stuttgan 1984, p. 153; the characteristic values for I-methylpyrrole are 5(2/3)=2.6, J(3/4)=3.5, J(2/
4) = 1.3 Hz.
[7] All the new compounds gave satisfactory spectroscopic data and elemental analyses.
[8] G. Kaupp, H. Voss, unpublished.
Regioselective Protonation of Allylic Anions**
By Siegfried Hiinig,* Norman Klaunzer, and
Riiger Schlund
Dedicated to Professor Klaus Hafner on the occasion of
his 60th birthday
Because of the great preparative importance of substituted allylic anions, numerous studies have appeared on
the a/y selectivity of their reaction with electrophiles such
as alkylating agents and carbonyl compounds."' However,
systematic investigations on the regioselectivity of protonation exist only with respect to substituent effects on allylic
anions,"' solvent effects?' and the use of various bases;[31
several allylmetal compounds have also been studied.141
The influence of the proton source XH, o n the other hand,
has either not been studied at all or only examined within
[*] Prof. Dr. S . Hiinig, Dip1.-Chem. N. Klaunzer, DipLChem. R. Schlund
[**I
Institut fur Organische Chemie der Universitat
Am Hubland, D-8700 Wurzburg (FRG)
This work was supported by the Deutsche Forschungsgemeinschaft (as
part of the program on "Noncovalent Interactions").
0 VCH Veriagsgeseiischafi mbH, 0-6940 Weinheim, 1987
0570-0833/87/1212-1281$ 02.50/0
1281
Документ
Категория
Без категории
Просмотров
2
Размер файла
254 Кб
Теги
dipyrrolo, quinoxalines, system, novem, heterocyclic
1/--страниц
Пожаловаться на содержимое документа