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Formation of Tetranuclear Chelate(4-) Ions of Divalent Metals (Mn Co Ni) with Idealized T Symmetry by Spontaneous Self-assembly.

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1.46(2) A, respectively). These bonds are considered to have
boron-carbon partial double bond character. They are
longer than the boronxarbon double bond distance of
1.361(4) 8, reported by Paetzold et al.,[’31 but shorter than
The “short” B-C distances
B-C single bonds (ca. 1.6
found in 1, 2, and 3 suggest that a strong boron-carbon
interaction is maintained throughout the transformation of
1 into 3, supporting an intramolecular process.
Compound 4 is a model compound for the proposed intermediate in the transformation of 1 into 3. The availability of
only one chlorine atom in Reaction (a) halts the conversion
of 1 into 3 and allows isolation of 4. The intermediacy of 4
is revealed by treating it with BX, to produce 3 (X = C1) or
the mixed halo derivative 3‘ (X = Br) and the boroxine
B,X,O,, (Scheme 2). This completes the conversion of 1 into
3. Scheme 2 is based on “B-NMR studies which indicate
initial formation of the 9-BBN halide, which would produce
the intermediate 5 proposed for the reaction of 1 with BCI,
when X = C1.
Compound 4 can also be considered to be an alkyne complex analogue. The B-C fragment adopts a p3,qz bonding
mode and is oriented nearly parallel to the Osl-Os2 bond.
The B-C unit along with the hydrogen atom bridging Os2BI, donate four electrons to the cluster.[’5]Two electrons are
donated to Os3 through a n-interaction and the two remaining electrons are distributed between a o-bond to Osl and a
hydrogen bridged bond to Os2.
Determination Package). The structure was solved by the direct method
MULTAN 11/82 and difference Fourier syntheses. Hydrogen atoms were
located and refined. R = 0.038 and R , = 0.048 (319 parameters refined)
for 2695 unique reflections ( I 2 3 o ( l ) ) of 3519 reflection collected in the
range of 4 I 2 6 5 45”. Further details of the crystal structure investigation are available on request from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftkh-technische Information mbH. D7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository
number CSD-54377, the names of the authors and the journal citation.
[11] D. D. A. Barratt, S . J. Davies, G. P. Elliott, J. A. K. Howard, D. B. Lewis.
F. G. A. Stone, J. Organomel. Chem. 325 (1987) 185.
[12] L. Pauling: The Nature ofthe Chemical Bond, 3rd edit., Cornell University
Press, Ithaca, NY, USA 1960, p. 229.
[13] R. Boese, P. Paetzold, A. Tapper, R. Ziembinski, Chem. Ber. 122 (1989)
1057.
[14] a) D. J. Saturnino, M Yamauchi, W. R. Clayton, W. R. Nelson. S. G.
Shore, J. Am. Chem. SOC.97(1975) 6063; b) L.-Y Hsu, J. F. Mariategui. K.
Niedenzu, S . G. Shore, Inorg. Chem. 26 (1987) 143.
1151 a) Alkynes adopting the pa, q2bonding mode donate four electrons to the
cluster through two 0 bonds and a IT interaction. b) E. Sappa, A. Tiripicchio, P. Braunstein, Chem. Rev. 83 (1983) 203, and references therein.
Formation of Tetranuclear Chelate(C) Ions of
Divalent Metals (Mn, Co, Ni) with Idealized
T Symmetry by Spontaneous Self-assembly
By Rolf W: Saalfrank,* Armin Stark, Matthias Bremer,
and Hans- Ulrich Hummel
Experimental
A CH,CI-solution (6 ml) of 9-Cl-9-BBN (74.3 mg, 0.474 mmol) was transferred
to a flask containing 82.1 mg, 0.095 mmol of 1. The reaction mixture was stirred
at room temperature for one hour, and the volatile components were then
removed leaving an oily yellow residue, which, on washing with pentane, furnished pale yellow 4: yield 72.5mg (0.071 mmol, 75%). IR (vco, CH,CI,):
J[cm-l] = 2010 m(sh). 2035s, 2075s, 2095s. 2117wcm-’. Satisfactory H,Canalysis. MS (EI): mjz 1027 ( W - 1 ) . 250.1-MHz ‘H-NMR (CD,CI,, 30°C):
6 = 1.90(m), 1.82(m). 1.39(m), -11.75 (br. s), -16.18(s), -21.87(s),
-21.87(s). 80.3-MHz “ B N M R (CD,CI,, 30’C): 6 = 58.8 (br. s), 18.5(s).
69.9 MHz ”C{’H)NMR (CD,CI,, 30°C): 6 = 138.0 (br.s. C-B), 175.03,
174.42, 172.75, 169.06, 168.26, 167.95, 166.06, 165.93, 162.51 (eachCO), 33.79,
33.57. 24.96 (br. s), 23.42 (9-BBN C-atoms).
Received: October 25, 1989 [ Z 3610 IE]
German version: Angew. Chem. 102 (1990) 328
CAS Registry numbers:
1, 86727-98-2; 3, 109801-61-8; 3, 125454-99-1; 4, 125454-97-9; 9-Cl-9-BBN,
22086-34-6.
[l] S. G. Shore, D.-Y. Jan, W:L. Hsu, L.-Y Hsu, J. Am. Chem. SOC.fO5 (1983)
5923.
[2] Fenske-hall calculations [3] have shown that this is the most negative
oxygen in the molecule.
[3] R. D Barreto, T. P. Fehlner, L:Y. Hsu, D.-Y. Jan, S . G. Shore, Inorg.
Chem. 25 (1986) 3572.
[4] D:Y. Jan, S. G. Shore, Organometallics 6 (1987) 428.
[5] D:Y. Jan, L.-Y. Hsu, D. P. Workman, S. G. Shore, Organomerallics 6
(1987) 1984.
[6] a) Previously reported examples involve reactions of anionic ketenylidene
clusters with electrophiles; b) J. A. Hriljac, D. F. Shriver, J. Am. Chem. Soc.
109 (1987) 6010; c) M. J. Went, M. J. Sailor, P. L. Bogdan, C. P. Brock,
D. F. Shriver, ibid. 109 (1987) 6023.
[7] G. W. Kramer, H. C. Brown, J. Organomet. Chem. 73 (1973) 1.
[8] The ability of a Lewis acid to induce a shift of a carbonyl ligand from a
terminal to a bridge site was first observed by Shriver et al. [9].
[9] a ) J. S. Kristoff, D. F. Shriver, Inorg. Chem. 13 (1974) 499; b) A. Alich,
N. J. Nelson, D. Stroppe, D. F. Shriver, a i d . f f (1972) 2976.
[lo] Crystals were grown at -40°C in CH,Cl,. Structure analysis at
-50°C: space group PT. u = 9.362(9), h = 11.586(4), c = 12.574(3) A,
a = 90.70(2)”, p = 91.40(5)”, y = 112.50(4)”, V = 1259.4A3, e..l.d =
2.692gcm-‘ for M = 1021.01, Z = 2 , p = 152.753cm-’ for Mo,..
Diffraction data were collected with an Enraf-Nonius CAD4 diffractometer. All data were corrected for Lorentz and polarization effects. An
empirical absorption correction was made. Crystallographiccomputations
were carried out on a PDPllj44 computer using the SDP (Structure
Angen. Chem. Int. Ed. Engl. 29 (1990) No. 3
Dedicated to Professor Paul von Ragut Schleyer on the occasion of his 60th birthday
The structures of enolates and their reactivity are currently
of great interest.[’] The same holds true for polynuclear metal complexes.[’1 Since a tetranuclear manganese cluster constitutes the active center in photosystem 11, which carries out
photooxidation of water in green plants and algae, tetranuclear manganese chelate complexes might serve as models for
the elucidation of this fundamental biological process.
Earlier we obtained the tetranuclear magnesium chelate
complex 3b in 85% yield by reaction of diethyl malonate
(I b), methylmagnesium iodide, and oxalyl chloride (2) in a
molar ratio of 1 :1:0.25 at -78 “C in tetrahydrofuran followed by workup in aqueous ammonium chloride solution.t3] We were convinced that, in addition to magnesium,
other divalent metals would also undergo such “spontaneous
self-assembZy”t41 to form similar “adamantanoid” chelate complexes. However, the alkylmetal chlorides of manganese, cobalt, and nickel are less readily available.[61We
have therefore modified our synthetic procedure for 3 b and
now use methyllithium/magnesium chloride instead of
methylmagnesium iodide. The advantage of this approach
lies not only in the slight improvement in yield of 3 b from
85 % to 90 % but also in the simpler experimental procedure.
Much more important than the more facile preparation of
3 b is the fact that mere replacement of magnesium chloride
by the chlorides of manganese, cobalt, and nickel allows the
[*I Prof. Dr. R. W. Saalfrank, DipLChem. A. Stark, Dr. M. Bremer [‘I
Institut fur Organische Chemie der Universitat Erlangen-Nurnberg
Henkestrasse 42, D-8520 Erlangen (FRG)
Priv. Doz. Dr. H.-U. Hummel [“I
Institut fur Anorganische Chemie der Universitat Erlangen-Nurnberg
[**I “Adamantanoid” Chelate Complexes, Part 2. This work was supported
by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen
Industrie. Part 1 : [3].
[‘I Single-crystal X-ray structure analysis of the Co complex.
[“I Single-crystal X-ray structure analysis of the Mn complex.
Q VCH Verlagsgesellschaf/ mbH, 0-6940 Weinheim, f 990
0570-0833/90/0303-031I $02.50/0
31 1
1 . M e M g I or
MeLi/MCI,
2
2. c'QCl 0
-
ROuOR
3. NH,CI/H,O
[Ed]
1
CNH?l4
4o
of zinc bromide results in formation of tetramethyl 2,3bis(benzoy1oxy)-I,3-butadiene-l, 1,4,4-tetracarboxylate (10;
yield 44%, m.p. 139°C).
The 'H and I3C NMR spectra of 4, 5, and 6 (electron
configurations: Mn", d5; Co'',
d7; NiZ', d8; paramagnetism) do not unambiguously establish the structure of
these compounds. Therefore, we choser8]to carry out X-ray
structure analyses of 4 a and 5a.['] The two compounds are
present as tetraammonium salts in the crystal. The counterions are the fourfold negatively charged, "adamantanoid",["I complex tetramanganate(4-) 4a4@ and tetracobaltate(4-) 5a4', respectively. Complexes 4 a and 5 a are
the first of this type.["' Complex 5a was chosen for graphical presentation (Figs. 1-3). The core of the complex tetra-
3.4.5.6
corresponding tetranuclear complexes 4,5, and 6, respectively, to be easily synthesized in good yields (80 to 87
The
doubly bidentate bridging ligand 7 is formally obtained by
template coupling of two malonate ester monoanions with
oxalyl chloride (2) to give the tetraalkyl 2,3-dihydroxy-I ,3butadiene-I ,I ,4,4-tetracarboxylate 8 followed by spontaneous double deprotonation of 8.
Under appropriate conditions, the 2,3-dihydroxy-I ,3-butadienes 8 may be isolated. Hydrolysis of 6 a under mild
conditions (pH = 5,20 "C, 2 min ultrasonication) affords 8 a
( k e t o m o l equilibrium; yield 46Y0, m.p. 77 "C). Compound
8 a reacts with bromotrimethylsilane/pyridine to give tetramethyl 2,3-bis(trimethylsiloxy)-l,3-butadiene-l,
1,4,4-tetracarboxylate (9; oil, yield 82Y0,dec. = 50 "C). Reaction of
9 with benzoyl chloride in the presence of a catalytic amount
H30Q
3b. 60
0 HxO
-
R
O
P
CO2R
W
O
R
Fig. 1. Top: Structure of the tetracobaltate(4-) chelate Ion 5a4e in the crystal
along the crystallographic C , axis. Bottom: Stereoview of 5a40 along the
crystallographic C , axis. 0 = 0, 0 = C, 0 = CH,.
~
cobaltate(4-) ion 5a4' is a distorted tetrahedron composed
of four cobalt(I1) ions [Co-Co distances: Col-Cola 660.6,
Col-Co2a and Co2-Cola 660.9, Col-Co2 and Cola-Co2a
669.6, Co2-Co2a 675.6 pm]; these ions are linked along
each of the six edges of the tetrahedron by a doubly bidentate
tetramethyl
2,3-dioxobutane-l,1,4,4-tetracarboxylato(2-)
bridge (7a), so othat each of the four cobalt(I1)
~
ions is octahedrally coordinated by six oxygen atoms["] [the torsional
angles 01-C2-C3-04 are 65.1, 73.9, 93.2, and 101.5"].
The tetracobaltate(4-) chelate ion 5a4' has exact C, symmetry in the crystal. Viewed ideally (the Co-Co distances
differ by less than 2.3 YO);however, the anion can be regarded as having nearly T symmetry (characterized by three C,
RH0
R02C
80. b
Ba
0
/
0 RxO
MeJSiBr
-
C02Me
M
OXR
C6H5COCI/ZnBrZ
D
10
312
0 VCH
R = SiMe3
R
=
C6HSC0
Verla~.~ge.~ellschaf~
mbH, 0-6940 Weinheim,1990
0570-0833190j03o3-0312 X 02.50/0
Anger?. Chem. Int. Ed. Engl. 29 (1990) No. 3
~
Fig. 2. Stereoview of the crystal packing of 5 a . For clarity, the hydrogen
atoms. the crystal water, and the 5a4e ions lying at the center in front of and
behind the plane of the figure are not shown. The ammonium ions are shown
as points. the chloroform molecules as three-pointed stars.
8 a : 6 a (1.1 g, 0.5 mmol) was suspended in 100 mL of water and treated with a
solution of 15 g of aluminum sulfate in 50 mL of water. After ultrasonication
of the reaction mixture for Zmin, the aqueous phase was extracted with
3 x 100 mL of dichloromethane. The extracts were dried over sodium sulfate
and the solvent was removed. The remaining yellow oil was crystallized from
chloroform/diethyl ether. Yield: 0.4 g (46%). colorless crystals, m.p. 77 “C. IR
(KBr): V = 1725 (C=O), 1650cm.’ (C=C). The ‘H and I3C NMR spectra
contained many signals ( k e t w n o l equilibrium). MS (70eV): mi; 318 ( M e ) .
9:8a(l.Og, 3 mmol)wasdissolvedin40 mLofdryTHF(underN,)and treated
with pyridine (0.5 g, 6 mmol) and bromotrimethylsilane (1.9 g, 13 mmol). The
reaction mixture was stirred for 1 h at 20°C and then filtered. The solvent was
removed and all volatiles were removed from the silyl enol ether at 20°C under
high vacuum. Yield: 1.2g (82%). Dec. -50°C. IR (neat): V = 1730 (C=O),
1635cm-’ (C=C). ’H NMR (400MHz, CDCI,): 6 =0.16 (s, 18H;
2Si(CH,),), 3.58 and 3.67 (each s. 12H; 4 C H J 13C NMR (100.5 MHz.
CDCI,): S = 0.15 (2Si(CH,),), 51.83 (4CH,, two coincidentally overlapping
signals), 112.37 (2 =C), 157.46, 163.95 and 164.28 (2 = C - 0 and 4 0-C=O).
MS (70 eV): m / z 434 ( M e - 28).
10:9 (1.O g, 2 mmol) was dissolved in 20 mL of dry dichloromethane (under N,)
and treated with benzoyl chloride (0.6 g, 4 mmol) and previously dried ZnBr,
(0.1 9). After 18 h, :he mixture was worked up with 20 mL of a saturated
aqueous solution of sodium hydrogen carbonate. The organic layer was dried
over sodium sulfate and the solvent removed. The remaining oil was crystallized
from diethyl ether. Yield: 0.5g (44%), colorless crystals, m.p. 139°C. IR
(KBr): V = 1750 and 1720 (C=O). 1640cm-’ (C=C). ‘H N M R (400 MHz.
CDCI,): 6 = 3.56 and 3.71 (each s, 12H; 4CH,), 7.49. 7.64 and 8.08 (each m,,
10H; 2C6H,). 13C NMR (100.5 MHz, CDCI,): 6 = 52.77 and 52.90 (4CH3),
128.70, 130.49(4C.,~huand4C,,,,.respectively),
120.81 (2 =C), 127.71 (2Czps0),
134.33 (2C,,J, 149.77 (2 =C-0), 162.03. 162.15, and 162.84 ( 6 0 - C = 0 ) . MS
(70 eV): m/z 526 ( M e ) .
Correct elemental analyses for 4a, 5 a , 6 a , 8a. and 10.
Received: September 22, 1989 [Z 3562 IE]
German version: Angew. Chem. 102 (1990) 292
Fig. 3. Space-filling model of 5 a (cocrystalhzed chloroform and water are also
shown) as viewed along the crystallographic C, axis. White, H atoms; black,
C atoms; violet, N atoms outside the “adamantanoid” chelate anion; red,
0 atoms; green. C1 atoms; blue, Co atoms inside the “adamantanoid” chelate
anion.
and four C , axes).1131Accordingly, the tetracobaltate(4-) ion
5a40 should be dissymmetric and thus chiral. The dissym-
metry of this tetranuclear anion results from the atropisom e r i ~ m [ ’ of
~ I ligands 7a. The six chelate bridges 7a linking
the four Co2@centers are twisted in the same sense and have
nearly C, symmetry. The chiral subgroups of the point symmetry groups of the regular tetrahedron T, are C,, C, , D,,
and T. Whereas numerous examples of molecules with C,
symmetry are known, there are only a few organic molecules
having the higher point-group symmetries (C, ,I1’] D 2 ,
T[”I). Only relatively complicated molecules can have T
symmetry. One of the reasons for the rarity of the highersymmetry chiral compounds is that the required geometric
prerequisites, all of which have to be simultaneously fulfilled,
make a non-directed formation improbable. All the more
surprising, therefore, is the high degree of symmetry obtained by “spontaneous self-assembly”.
Experimental Procedure
4a, 5 a , 6 a : 30 mmol of a 1.6 M solution of methyllithium in diethyl ether was
added to a solution of I a (4.0 g, 30 mmol) in 50 mL of dry T H F (under N,,
- 78 ‘‘2).The reaction mixture was stirred for 1 h at - 78 ”C followed by addition of 30 mmol of previously dried MCI, (4a. MnCI,; 5 a , CoCI,; 6 a , NiCI,).
After stirring for 1 h, the mixture was treated dropwise with oxalyl chloride (2;
0.9 g. 7 5 mmol) in 20 mL o f T H F over 30 min, then allowed to warm over 18 h
to 20‘C. and finally worked up with aqueous ammonium chloride solution.
4 a : yield 2.2 g (80%). colorless prisms from CHClJhexane, dec. 185 “C. IR
(KBr): i.= 1685 (C=O), 1625cm-’ (C=C).
5 a : yield 2.4 g (87%), violet prisms from CHCl,/hexane, dec. -193°C. IR
(KBr): V = 169O(C=O), 1625cm-‘ (C=C).
6 a : yield 2.4g (87%). green prisms from CHCl,/hexane, dec. -160°C. IR
(KBr): i.= 1685 (C=O), 1620cm-’ (C=C).
-
Angen.. Chem. lnt. Ed. Engl. 29 (1990) No. 3
[I] D. Seebach, Angew. Chem. f00 (1988) 1685; Angew. Chem. I n t . Ed. Engl.
27 (1988) 1624.
121 K . Wieghardt, Angew. Chem. fOl(l989) 1179; Angew. Chem. Int. Ed. Engl.
28 (1989) 1153. We thank Prof. Dr. K . Wieghardt for a preprint of this
work; W. F. Beck, J. Sears, G. W. Brudvig, R. J. Kulawiec, R. H. Crabtree,
Tetrahedron 45 (1989) 4903.
[3] R.W. Saalfrank, A. Stark, K. Peters, H. G. von Schnering, Angew. Chem.
100 (1988) 878; Angew. Chem. Int. Ed. Engl. 27 (1988) 851.
[4] Formation of the thermodynamically most stable product, having a special
structure, under appropriate conditions (concentration, temperature, solvent) from labile, mononuclear metal complexes, multidentate ligands,
and bridging ligands [2, 51.
[5] JLM. Lehn, A. Rigault, Angew. Chem. fOO(1988) 1121; Angew. Chem. Int.
Ed. Engl. 27(1988) 1095; L. A. Ibers, R. H. Holm,Science209(1980)223.
[6] C. Eaborn, P. B. Hitchcock, J. D. Smith, .
I
Chem. Soc. Chem. Commun.
1985, 535.
[7] The use of sodium hydride/metal chloride has so far given ca. 15 % lower
yields. The multistep process used, for example, in the synthesis of the
corresponding zinc chelate complex [3] cannot compete wi:h these one-pot
procedures. In this process, hydrolysis of the magnesium chelate complex
3 b initially yields the tetraethyl ester 8b. Reaction of 8 b with sodium
hydridelzinc bromide proceeds via the free doubly bidentate chelate anion
7b to afford, after workup with aqueous ammonium chloride solution. the
“adamantanoid” zinc chelate complex, but only in yields of ca. 66%
(based on 3 b).
[8] In addition to 4a,b, 5a,b, and 6a,b, the corresponding complexes with
R = tert-butyl or benzyl were also synthesized. In all cases, beautiful crystalline compounds were obtained, although only the methyl-substituted
derivatives (a series) were suitable for X-ray analysis.
(NH,),, colorless prisms from chloroform/hexane.
[9] 4 a : C,,H,,O,,Mn,
The compound crystallizes with two equivalents of chloroform and water.
Single crystals, 0.3 x 0.5 x 0.5 mm3; monoclinic, space group C2/c
(No.15), a = 2607.6(5), b = 1747.3(3), c = 2303.4(5) pm, = 101.43(7)”,
V = 10287 x lo6 pm3, 2 = 4; Philips PW 1100 diffractometer, graphite
monochromator, Ag,= radiation, I = 0.55943 A, SHELXS-86 and
SHELX-76 program systems, 16300 reflections measured (4 < 2 0 < 4 0 ,
w scan with scan width [1.2 + 0.2 tan@]”. Averaged data set’ 4082 reflections, 2288 “observed” reflections with F > 6 4 0 . R = 0.077. R, = 0.080;
(NH,),, vio328 parameters refined block-diagonally. 5 a : C,,H,,O,,Co,
let parallelepipeds from chloroform/hexane. The compound crystallizes
with two equivalents of chloroform and water. Single crystal,
0.5 x 0.4 x 0.4 mm3; monoclinic, space group C2/r (No. 15). a =
2568.8(6), b = 1729.9(4), c = 2276.0(6) pm, = 101.33(2), V = 9916 x
lo6 pm3, 2 = 4; Nicolet R3m/V diffractometer. graphite monochroma= 0.71073 A, SHELXTL PLUS program system,
tor, Mo,, radiation, i.
11371 reflections measured (4 < 2 0 < 54”, w scan with 3-15” min-’ in
Q VCH Verlagsgesellschaft mbH, 0-6940 Weinheim. 1990
0570-0833~90/0303-03138 02.50jO
313
w ) . Averaged data set: 9748 reflections, 7382 “observed” with F > 6a(F).
R = 0.059, R, = 0.063; 708 refined parameters. Further details of the crystal structure investigation may be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftiich-technischeInformation mbH, D-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the
depository number CSD-54193, the names of the authors, and the journal
citation.
[lo] Schematic representation.
[ l l ] The band patterns and characteristics of the IR spectra Indicate that compounds4b, 5b, and 6a, b and thecorresponding complexes with R = tertbutyl or benzyl have the same structures as 4 a and 5a .
[12] Concerning the topology of the tetranuclear chelate a n i 0 n s 4 a ~and
~ 5a4e
(bridgeheads: M z@ions), compare the relationships in spherical tricycles
(bridgeheads: N atoms): J. M. Lehn, Angew. Chem. 100 (1988) 91; Angew.
Chem. I n ! . Ed. Engl. 27 (1988) 89; Pure Appl. Chem. 49 (1977) 857; E. Graf,
J. M. Lehn, J Am. Chem. SOC.97 (1975) 5022; E. Weber, F. Vogtle, Kontakte (Darmsradt) 1981. No. 1, p. 24; E. Weber: Phase Transfer Caralysts,
Properties and Applicarions (Merck-Schuchardt 1987), p. 33; F. P.
Schmidtchen, Angew. Chem. 89 (1977) 751 ; Angew. Chem. Int. Ed. Engi. 16
(1977) 720; Nachr. Chem. Tech. Lab. 36 (1988) 8.
[13] R. S. Cahn, C. K. Ingold, V. Prelog, Angew. Chem. 78 (1966) 413; Angew.
Chem. In/. Ed. Engl. 5 (1966) 385; G. Haas, V. Prelog, Helv. Chim. Acta.
52 (1969) 1202.
[14] Cf. M. Rosner, G. Kobrich, Angew Chem. 86 (1974) 775; Angew. Chem.
I n t . Ed. Engl. 13 (1974) 741; R. W. Saalfrank, W. Paul, P. Schierling, Chem.
Ber. 118 (198s) 2150; G. Becher, A. Mannschreck, &id. 116 (1983) 264.
[15] A. de Meijere, 0. Schallner, Angew. Chem. 85 (1973) 400; Angew. Chem.
Inr. Ed. Engl. 12 (1973) 399; S. Nishigaki, K. Aida, K. Senga, F. Yoneda,
Tetrahedron Letl. 1969, 247; R. C. Fort, W. L. Semon, J Org. Chem. 32
(1967) 3685.
[16] K. Mislow, M. A. W. Glass, H. B. Hopps, E. Simon, G. H. Wahl, Jr., J
Am. Chem. SOC.86 (1964) 1710; M. Nakazaki, K. Naemura, Y Kondo, J
Org. Chem. 41 (1976) 1229; H. J. Bestmann, W. Schaper. Tetrahedron Lett.
1975,3511; H. Irngartinger, Chem. Ber. 106(1973)761,2796;M. NakazaChem. Commun. 1972,433;
ki, K. Yamomoto, S. Tanaka, J Chem. SOC.
D. J. Cram, K. C. Dewhirst, J. Am. Chem. SOC.81 (1959) 5963.
[17] H. Irngartinger, A. Goldmann, R. Jahn, M. Nixdorf, H. Rodewald, G.
Maier, K.-D. Malsch, R. Emrich, Angew. Chem. 96 (1984) 967; Angebv.
Chem. Int. Ed. Engl. 23 (1984) 993.
1,2,4-diazaphospholes 3 a, b is followed by spontaneous sigmatropic [1,5]-shift of the R,P residue to give the isomers
4a, b.[61 Since ‘JPpcouplings are absent in the 31P-NMR
spectra, and since the I3C-NMR spectrum of 4a shows only
sp2 ring carbon atoms with comparably large phosphorus
couplings (6 = 189.2, 199.2, ‘JPc= 59.1 and 63.0 Hz), the
phosphino substituent must be bound to one of the nitrogen
atoms.[’]
R
1
‘P-C-tBu
R’
I/
N2
I
R
b, R
a,
= O Me
=
3
Ph
4
In contrast 1 a, b react quite differently, and in the sense of
a [4 + 21-cycloaddition, with the electron-deficient alkynes
Sa, b: the previously unknown 1,2,4-h5-diazaphosphinines
7a-d are formed in good yields. The special role played by
the phosphino residue in this reaction is best expressed in
terms of a nucleophilic attack at the alkyne carbon atom
(+ 6), followed by a 1,6-ring closure leading to 7.
1
14 + 21-Cycloadditions of Phosphinodiazoalkanes:
Synthesis of 1,2,4-3L5-Diazaphosphinines
**
Et20/C6H6
25°C
A
5a, R
=
5b, R
=
6
OMe
Ph
By Thomas Facklarn, Oliver Wagner, Heinrich Heydt,
and Manfred Regitz *
Dedicated to Professor Alfred Schmidpeter on the occasion of
his 60th birthday
There is no reaction which so compellingly characterizes
aliphatic diazo compounds as 1,3-dipolar cycloaddition.
This behavior has been documented in numerous reactions
with double- and triple-bonded systems, and has been used
for the synthesis of heterocycles.[’] It is all the more surprising that the phosphinodiazoalkanes first reported a few years
ago[’] undergo either [3+2]- or even, as presented here,
[4 + 21-cycloadditions, depending on the cycloaddition partners.
As model substances, we have used the phosphinodiazoalkanes 1 a and 1 b,13] which are readily accessible by electrophilic diazoalkane substitution L41 of lithium 1-diazo-2,2dimethylpropane with the corresponding chlorophosphane.
Their reaction with the phosphaalkyne 2,[51which possesses
an electron-rich triple bond, still proceeds “normally”: the
regiospecific [3+ 21-cycloaddition step leading to the 3 H[‘I
Prof. Dr. M. Regitz, Dr. T. Facklam, Dr. 0. Wagner, Dr. H. Heydt
Fachbereich Chemie der Universitat
Erwin-Schrodinger-Strasse,D-6750 Kaiserslautern (FRG)
[**I Diazo Compounds, Part 71. This work was supported by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen 1ndustrie.Part 70: M. Regitz, M. Bohshar, S. Arenz, H. Heydt, Chem. Ber. 122
(1989) 565.
314
0 VCH
Verlagsgesellschaf/ mbH, 0-6940 Weinheim. 1990
A
7
B
In general, the transition 1 + 7 is characterized by an upfield shift of the 31P-NMR resonance signal, which is especially striking upon methoxy substitution at the phosphorus
(cf. Ref. [3] and Table 1). In the I3C-NMR spectra of 7a-d,
the ylidic character of C-5 is indicated by the high-field
resonances at 6 = 65.1-104.0 (lJPc= 95.6-131.8 Hz)
(7A -7B);[*] C-3 is clearly identifiable by the unmistakable
broadening of its signal in the ‘H-decoupled I3C-NMR
spectrum (small 3J(H,C)-coupling). That the six-membered
ring is no longer planar is immediately evident from the
presence of two magnetically different P-methoxy groups
for 7 a and 7 b, only one of which, however, shows a distinct
3J(P,H) coupling in the ‘H-NMR spectrum (see Table 1).
The crystal structure analysis carried out on 7 c shows that
the heterocycle has a distorted boat conformationr9I(Fig. 1);
3L5-phosphinines without further heteroatoms, on the other
hand, are planar.“’]
The deviations from the least squares plane for the atoms
N2, C3, C5, C6 are -0.038, 0.040, 0.044 and -0.047&
respectively. The angles between this plane and the P-C3-C5
and NI-N2-C6 planes are 22.67 and 10.77”, respectively.
0570-0833/90/0303-0314$02.50/0
Angew. Chem. Int. Ed. Engl. 29 (1990) No. 3
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