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Methoxyallenes as Components in Diels-Alder Reactions with Inverse Electron Demand Synthesis of 6H-1 2-Oxazines.

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Direct observation of the host-guest configuration was
made possible by the determination of the crystal structure
Of
-acetate.'71It 'Onfirms the 'ymmetric bonding pattern
of the acetate ions via two H-bridges to both N-atoms of
the guanidinium counterion (Fig. 2). The guanidinium
fragment is, to a very good approximation coplanar with
the acetate ion and the H-bridge system; this can be regarded as a n indication of considerable stability of the observed host-guest interaction. The short N2.. .001 distance
(2.850(5) A) also indicates that the H-bridges are strong.
Moreover, there is a further connection between host and
guest via two of the side chains of 3 by two further Hbridges 01-HO1 ... 001"(01 ... 001"2.733(5) A) to acetate
0-atoms. Particularly remarkable is the fact that, at least in
the crystal, this connection is not intramolecular but links
the cation-anion pair 3 -acetate into polymer strands (Fig.
2).
C4"'
c4 "
(1988) 1009 (Nobel lecture); F. Diederich, Angew. Chem. 100 (1988) 372;
Angew. Chem. I n [ . Ed. Engl. 27 (1988) 362; J. Rebek, Jr., Science Washington 235 (1987) 1478.
131 a) J. F. Riordan, Mol. Cell. Brochem. 26 (1979) 71; b) K. W. Hart, A. R.
Clarke, D. B. Wigley, A. D. B. Waldman, W N. Chia, D. A. Barstow, T.
Atkinson, J. B. Jones, J. J. Holbrook, Biochem. Biophys. Arta 914 (1987)
294.
141 a) R. D. Gandour, Bioorg. Chem. I0 (1981) 169; b) A. M. Sapse, C. S .
Russel, THEOCHEM. 30 (1986) 43.
[ S ] F. P. Schmidtchen, Chem. Ber. 113 (1980) 2175.
161 The "NMR
spectra were measured by polarization transfer experiments (DEPT; J ( N H ) = 9 0 Hz; 8 = 9 0 " with 'H-decoupling). Only the
protonated guanidinium N-atoms are observed. The signal shifts A 6 due
to complex formation are 5 3 ppm in CDICN.
171 Crystal structure data of 3 .acetate: C2,H,,O6N3,M,=431.58, orthorhombic, space group Pnma (No. 62), a= 12.415(2), b=24.464(3),
1.263 g cm-', p(MoKn)=0.9
c=7.474(1) A, V=2270.0 A', 2 = 4 , pcJiuJ=
cm-', F(OOO)=944, T = -35°C. Syntex P2, diffractometer, Mo,, radiation, A=0.71069
graphite monochromator. 341 l measured reflections
(hkl: f 1 3 , +26, +8), 1615 independent and 1211 "observed" with
Solution by
Fo24.0ff(F0) (w scan, Aw=O.9", (sin8/A),,,=0.594
direct methods (MULTAN-87), R(R,,)=0.066 (0.059), w = I/a2(Fo)
(anisotropic, H2 isotropic, all other H-atoms constant in observed positions
e k3.
with U,,,=O.OS A', SHELX-76). Apf,,(max/min)=0.33/-0.30
Further details of the crystal structure investigation are available on request from the Fachinformationszentrum Energie, Physik, Mathematik
GmbH, D-7514 Eggenstein-Leopoldshafen2 (FRG), on quoting the depository number CSD-53239, the names of the authors, and the journal
citation.
A,
A-').
Methoxyallenes as Components in
Diels-Alder Reactions with Inverse Electron
Demand: Synthesis of 6H-1,2-Oxazines**
By Reinhoid Zimmer and Hans- Ulrich Reissig *
02'
02
Fig. 2. Section of the crystal structure of 3.acetate (ORTEP, atoms with arbitrary radii, only N- and 0-bonded H atoms are shown). The molecular
moiety 3 .acetate has crystallographic mirror symmetry, the mirror plane
contains the atoms N I , C1, CO1 and C02. The illustrated strands ( 3 .acetate),
are generated by a crystallographic glide plane (a) and connected with one
another by four H-bridges per 3.acetate ( 0 2 - H 0 2 ... 01*/02*-H02* ... 0 1 ;
indicated by arrows) via inversion centers.-Important bond lengths [A] and
angles ["I: NI-CI 1.333(7), N2-CI 1.338(5), COI-C02 1.497(8), COI-001
1.258(4); NI-Cl-N2 121.4(3), N2-CI-N2' 117.2(5), CO2-COI-001 I18.5(3),
001-COI-001' 123.1(6). H-bridges: N2-H2.. .001 0.88(4)/1.97(4), 0 1 H 0 1 - . -001"
(-0.5+x,y,2.5-z)
1.08/1.66,
02-HO2.. .01*
( - x, 1 -y,2 -2) 1.20/1.70.
During the last few years acceptor-substituted allenes
have been used for various pericyclic reactions."] In contrast, electron-rich allenes, some of which are much more
readily accessible, have hardly been employed at all. Herein we report on Diels-Alder reactions with inverse electron
demand['] involving various methoxyallenes.
The nitrosoalkenes 2, generated in situ from a-halo oximes 1 and sodium carbonate (Scheme l),"] add smoothly
to methoxyallene 3(41(five equivalents). Of the four conceivable regioisomeric cycloadducts, only the heterocycles
4 containing an exo-methylene group at C-5 are formed, as
H o l T R
Hal
Since these H-bridges are shorter they must be even
stronger than those between acetate ion and guanidinium
fragment, which is consistent with the NMR observations.
The two remaining side chains surprisingly d o not participate in the host-guest interaction, but couple the strands
together by H-bonding with the hydroxy 0-atoms 01* of
neighboring guanidinium ions 3, so that all NH- and OHfunctions participate in H-bonding in the crystal.
Received: May 30, 1988 [ Z 2790 IE]
German version: Angew. Chem. 100 (1988) 1574
CAS Registry numbers:
Z0.p-N02C6H4COY, 117161-61-2; 3 e . A c 0 Q , 117161-62-3
0 VCH Verlagsgesellschaft mbH. 0-6940 Weinheim. 1988
[JR]
2
R
l a~.CI
Ph
lb
Br
C0,Et
lc
Br
CF3
I
>
I1
"O'I"" 3
.
II
MeOAO"
5 a , 97%
b. 71%; c . 75%
I
or NEt3
I
ll
MeOAO"
4a, 79%
b, 76%; c , 71%
Scheme 1. Synthesis of 6H-1,2-oxazines 4 and 5 . The yields given are based
on 1 o r 4, respectively.
[*I
[ I ] a) F. P. Schmidtchen, J. Am. Chem. Sor. I08 (1986) 8249; b) Nachr. Chem.
Tech. Lab. 8 (1988) 10.
[2] For other concepts on the design of synthetic host-guest molecules see D.
J. Cram, Angew. Chem. 100 (1988) 1041; Angew. Chem. Inr. Ed. Engl. 27
1518
Me0
Na,CO,t Bu
HOXN
Prof. Dr. H.-U. Reissig, Dipl.-Ing. R. Zimmer
Institut fur Organische Chemie der Technischen Hochschule
Petersenstrasse 22, D-6100 Darmstadt (FRG)
I**] This work was supported by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and the Karl-Winnacker-Stiftung
(Hoechst AG).
0570-0833/88/11l1-1518 $ 02.50/0
Angew. Chem. Inr. Ed. Engl. 27 (1988) No. I 1
expected in view of the electronic properties of the reaction partners.[51Conjugation of the exocyclic double bond
may be achieved by treatment with bases or, more quickly,
under acid catalysis. The 6H-1,2-oxazines 5 are thereby
obtained in good yields.
Since 3 can be easily substituted at C-1 by deprotonation and subsequent reaction with electrophiles,[61 it is also
possible to synthesize 1,2-oxazine derivatives containing
two substituents in the 6-position. Whereas the addition of
2 to I-al kylated methoxyallenes affords only moderate
yields (e.g., 309'0 yield of I-methyl-1-methoxyalleneand
2a), the sterically encumbered hydroxylated allenes 6 and
7 give the functionalized heterocycles 8 and 9, respectively, with reasonable efficiency. A moderate diastereoselectivity (60 :40) was found in the cycloaddition of 2a to 7 to
give 9. The products 8 and 9 can also be transformed into
the conjugated systems 5 by treatment with base.
"
LR.
+
2a
Na2C03
Me0 t Bu
Me0
6
R' = C(OH)Me2
7
R' = CH(0H)Me.
Me0
R'
8 , 49%
9. 56%
(60 : 40)
1,2-Oxazines are compounds of little explored but readily apparent synthetic potential."] We therefore investigated transformations of the heterocycles 5 . Oxidation of
10, 69%
Ph
11, 73%
WPh
Me0
5a
- 78+2OoC
BF3. OEtp
HSiEt3
5a with pyridinium chlorochromate (PCC) affords the 1,2oxazin-6-one 10 ;I8] treatment with BF3. OEt2/allyltrimethylsilane results in C-C bond formation to give 11. This
reaction, like the reduction with triethylsilane in the presence of the Lewis acid BF,.OEt, to give 12, probably proceeds via the intermediacy of an azapyrylium ion.['] Reaction of 5a with aluminum
gives the pyrrole
derivative 13.['01 These reactions point to the diverse possible reactions of 6H-1,2-oxazines. Table 1 contains relevant
physical data of characteristic compounds.
Received: June 14, 1988 [Z 2813 IE]
German version: Angew. Chem. 100 (1988) 1576
CAS Registry numbers:
l a , 21572-32-7; Ib, 73472-94-3; Ic, 117341-57-8; 3, 13169-00-1; 4a, 11734158-9; 4b, 117341-59-0; 4c, 117341-60-3; 5a, 117341-61-4; 5b, 117341-62-5; 5c,
117341-63-6; 6, 22141-88-4; 7, 22141-90-8; 8, 117369-63-8; 9 (isomer I),
117341-64-7; 9 (isomer 2), 117341-65-8; 10, 113549-23-8; 11, 117341-67-0; 12,
117341-66.9: 13, 20055-04-3; allyltrimethylsilane, 762-72- I.
[I] a) A. Bosum, S . Blechert, Angew. Chem. 100 (1988) 596; Angew. Chem.
I n t . Ed. Engl. 27 (1988) 558; b) S. E. Denmark, M. A. Harmata, K. S .
White, J. Org. Chem. 52 (1987) 4031; c) A. Padwa, S. P. Craig, U. Chiacchio, D. N. Kline, h i d . 53 (1988) 223 1 ; d) G. Himbert, D. Fink, K. Diehl,
Chem. Ber. I21 (1988) 431, and earlier work of these groups and references cited therein.
[2] a) Recent reviews: D. L. Boger, Terruhedron 39 (1983) 2869; D. L. Boger,
S . N. Weinreb: Herero D i d - A l d e r Merhodology in Organic Synthesis.
Academic Press, New York 1987; b) for the incompletely described
reaction of allene with a 1,2,4,5-tetrazine, see R. A. Carboni, R. V. Lindsey, Jr., J. Am. Chem. SOC.81 (1959) 4342; c) recently, the intramolecular
cycloaddition of a molecule with an allene and with a IJdiazine unit
was reported: D. L. Boger, S . M. Sakya, J. Org. Chem. 53 (1988) 1445;
Note added in proof (October 5 , 1988): A hetero-Diels-Alder reaction
with inverse electron demand using 3 under high-pressure conditions
was very recently published: D. L. Boger, K. D. Robarge, &id. 53 (1988)
3373.
131 Review: T. L. Gilchrist, Chem. SOC.Rev 12 (1983) 53.
[4] S. Hoff, L. Brandsrna, J. F. Arens, R e d Truu Chim. Pays-Bus 87 (1968)
916; F. J. Weiberth, S . S . Hall, J. Org. Chem. 50 (1985) 5308.
[5] MO coefficients of methoxyallene: M. Yoshida, Y . Hidaka, Y. Nawata,
J. M. Rudzinski, E. Osawa, K. Kanematsu, J. Am. Chem. SOC./ I 0 (1988)
1232.
[6] S . Hoff, L. Brandsma, J. F. Arens, R e d Truu. Chim. P q s - B u s 87 [ 1968)
1179.
[7] See a) E. J. Chrystal, T. L. Gilchrist, W. Stretch, J. Chem. Res. (Sj 1987.
180; J . Chem. Res. ( M ) 1987, 1563 and earlier work of this group; b) C.
Hippeli, H.-U. Reissig, Synrhesis 1987. 77; see also transformations of
the related isoxazolines: V. Jager, I. Miiller, R. Schohe, M. Frey, R.
Ehrler, B. Hafele, D. Schroder, Leer. Hererocycl. Chem. 8 (1985) 79, and
references cited therein.
[S] A. Padwa, U. Chiacchio, D. N. Kline, J. Perurnattam, J. Org. Chem. 53
(1988) 2238.
191 For the formation of azapyrylium salts, see Q. B. Broxterman, H. Hogeveen, R. F. Kingma, F. van Bolhuis, J . Am. Chem. SOC.107 (1985) 5722,
and references cited therein.
[lo] T. W. Thompson, Chem. Commun. 1968. 533.
nPh
12, 89%
Table I. Physical data of characteristic compounds [a]
4 a : b.p. 9O0C/O.06 torr; 'H NMR: 6=7.76-7.68, 7.45-7.35 (2m, 2 H , 3 H ;
Ph), 5.22, 5.12 (2d, 'J=2.5 Hz, each 1 H ; =CH2), 5.21 ( s , 1 H ; 6-H), 3.51 ( s ,
3 H ; OMe), 3.50, 3.19 (td, d, AB part of a ABXY system, 4J=2.5, 2JAB=
19.5
Hz, 2 H , 4-H); I3C NMR: 6=156.2 ( s ; C-3), 135.2, 134.9 (2s; C-5, @so-C),
129.9, 128.5, 125.5 (3d;Ph), 112.3 (t; =CH2), 99.6 (d; C-6), 55.3 (4; OMe),
19.2 (t; C-4)
5 a : b.p. 95"C/0.06 torr; 'H NMR: 6=7.78-7.67, 7.48-7.32 (2m, 2 H , 3 H ;
Ph), 6.32 (4. 'J= 1.5 Hz, 1 H; 4-H), 5.31 (s, 1 H; 6-H), 3.53 ( s , 3 H; OMe), 2.05
(d, 'J= 1.5 Hz, 3 H ; 5-Me); "C NMR: 6 = 154.1 Is; C-31, 137.5, 134.1 (2s;
C-5, ipso-C), 129.5, 128.6, 126.2 (3d; Ph), 111.9 (d; C-4), 97.1 (d; C-6), 55.9
(4; OMe), 19.3 (q; 5-Me)
12: m.p. 31.5-33OC; ' H NMR: 6=7.7-7.6, 7.4-7.3 (2m, 2 H , 3 H ; Ph), 6.18
(br. s , I H ; 4-H), 4.38 ( s , 2 H ; 6-H), 1.96 ( s , 3 H ; 5-Me); "C NMR: 6 = 156.8
( S ; C-3), 141.4 ( S ; C-S), 134.0, 129.8, 128.6, 126.0 (s. 3 d ; Ph), 110.9 (d; C-4),
66.5 (t; C-6), 19.6 (4; 5-Me)
[a] All compounds gave satisfactory elemental analyses and appropriate
spectra. 300 M H z ' H NMR and 75.5 MHz "C NMR spectra in CDCI, with
TMS as standard.
Angew. Chem. Inr. Ed. Engl. 27 (1988) No 11
Tetrakidbis(trimethylsilyl)ethyne]diiron* *
By Hartmut Schaufele, Hans Pritzkow, and
Ulrich Zenneck*
Dedicated to Professor Heinrich Noth
on the occasion of his 60th birthday
The existence of homoleptic transition-metal alkyne
clusters is, to the best of our knowledge, only clearly supported by one example so far, tris[bis(trimethylsi[*I Dr. U. Zenneck, DipLChem. H. Schaufele, Dr. H. Pritzkow
Anorganisch-chernisches Institut der Universitat
Im Neuenheimer Feld 270, D-6900 Heidelberg (FRG)
[**I Reactive n-Complexes of the Electron-rich Transition Metals, Pan 7.
This work was supported by the Stiftung Volkswagenwerk. Part 6 [I].
0 VCH Verlugsgesell.schufr mbH, 0.6940 Weinheim. 1988
0570-0833/88/1lll-1S19 S 02.50/0
1519
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synthesis, oxazine, reaction, methoxyallenes, components, alder, electro, diels, inverse, demand
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