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Thermally Induced Ring Cleavage of a 2H-1 2-Azaphosphirene Tungsten Complex.

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N M R spectroscopic data characteristic of this type of compound and this substitution pattern of the ring carbon atoms
(Table 1) (cf.[*l).The IR spectroscopic and mass spectrometric
dataLg1
also support the proposed nature of 4a,b.
Thermally Induced Ring Cleavage of a
2H-1,2-Azaphosphirene-Tungsten Complex**
Rainer Streubel,* Annette Kusenberg, Jorg Jeske,
and Peter G. Jones
Dedicutrd to Professor Reinhard Schmutzler
on the occasion of his 60th birrhday
Table 1 Selected spectroscopic data ol'4a,b and 7 [a]
Because of their ability to generate 1,3-dipoles as reactive
intermediates on ring-opening, unsaturated three-membered
heterocycles are of great preparative interest for the generation
of five-membered heterocycles.['] Of three-membered heterocycles possessing the structural element C=N, only the 2H-azirenes have been extensively investigated with respect to their
ring-opening reactions.[2 41 Thus 2H-azirenes with an sp3-hybridized carbon in the 2-position predominantly display reactions, thermal and photochemical, in which the first step is the
breaking of one ring bond (route a and b).['] In contrast, the
2-methylene-2H-azirenes, which have an sp2-hybridized atom at
the 2-position, undergo photochemical reactions that result in
ring cleavage (route c)l3] (Scheme 1).
4 a : ' H NMR: 6 = 0.07 (s. 9 H ; SiMe,). 0.25 (s, 9 H: SiMe,). 0.5X (d.'J(H.P) =
2.41 Hz. 1 H : P C H ) , 7.48 (m. 3 H ; Ph). 7.68 (m. 2 H; Ph), 8.40 (d. 'J(H.P) = 21.6
Hz; C = C H ) : "C { ' H I N M R : 6 = l . 5 6 (d. 'J(C,P) = 3.09 Hz. SiMe,). 1.86 (d.
'J(C,P) = 3.74 Hz; SiMe,). 27.75 (d, 'J(C.P) = 27.24 H L : PCH(SiMe,),), 124.66
(d, 'J(C.P) = 6.48 Hz; PCH=C). 128.07 (d. 'J(C.P) = 6.09 Hz; f-C), 129.11 ( s ;
m-C). 129.24 (d. '4C.P) = 2.64 Hz. o-C). 130.82 (i:p - C ) . 145.82 (d,
'J(C.P) =17.86 Hz; PC=CH). 197.18 (dd, './(C.P) = 8.49 Hz: 'J(C.W) = 108.03
Hz: trs-CO). 198.93 (d, 'J(C.P) = 31.11 HL: rrtm.r-CO): "P : ' H ) N M R :
6 = -136.75 (d. 'J(P.W) = 272.08 Hz).
4b: ' H NMR: d = 0.07 (s, 9 H: SiMe,),0.13 (s, 9H: SiMe,),0.27 (d.'J(H.P) = 2.98
Hz. 1 H ; PCH(SiMe,),), 7.33 (m, 6 H: Ph), 7.52 (m, 4 H ; Ph): 'IC [ ' H i N M R :
6 =1.06 (d, 3J(C,P) = 2.87 Hz; StMe,), 1.74 (d, '4C.P) = 3.18 H7; SiMe,), 27 89
(d. 'J(C,P) = 30.28 Hz; PCH(SiMeJZ). 128.82 (d. 'J(C.P) = 3.42 HL: 0-C). 128.97
(s; m-C). 129.18 (d, 'J(C.P) = 6.22 Hz; i-C),129.99 (s: p-C). 136.04 (d,
'J(C.P) ~ 1 2 . 4 8Hz; P(Ph)C=), 197.38 (dd. 2J(C.P) = 8.30 Hz; ' J ( C . W ) = 91.78
Hz; cis-CO), 198.58 (d, 'J(C,P) = 30.36 Hz; truns-CO): "P j l H ) NMR:
d = - 134.60 (d, 'J(P.W) = 268.64 Hz).
~
.'
a
C.-.
.-..
---.#-
Scheme 1. Schematic representation of the ring-openmg reactions of 2H-azirenes (the substituents are unspecified; for the
2-methylene-2H-azirenes the bonds at the 2-position are
formed to the same atom).
b
/c=N
We report here the first example of a thermally induced ring
cleavage of the 2H-1,2-azaphosphirene tungsten complex 115]in
the presence of acetylene derivatives and in the presence of benzaldehyde.
The tungsten complex 1 is thermally labile in toluene in the
presence of phenylacetylene (2 a) or diphenylacetylene (2 b), and
the corresponding 1H-phosphirene tungsten complexes 4 a and
4 b, respectively, are formed. Since five-membered heterocycles,
for example as products of the reaction between 2a,b and a
conceivable 1,3-dipole generated from 1, were not observed, the
assumption of a terminal phosphanediyl tungsten complex 3 as
[(Me,Si),HCPW(CO),]
3
7: 'HN M R : 6 = 0.31 (s, 9 H ; SiMe,), 0.37 (s, 9 H ; SiMe,). 0.88 (d.'J(H.P) = 6.16
Hz. 1 H; PCH(SiMe,),), 4.34 (d. 1 H, 'J(H.P) = 2.05 Hz; P h C H ) , 7.47 (m. 3 H ;
Ph), 8.10 (m. 2 H. Ph); I3C { ' H i NMR: 6 =1.66 (d, 3J(C.P) = 4.26 Hz, SiMe,),
1.97 (d. 'J(C,P) = 2.29 Hz; SiMe,). 32.49 (d, 'J(C,P) =18.96 Hz. P('H(SiMe,),),
59.71 (d. 'J(C,P) = 27.33 Hz: PCO). 125.64 (d, 'J(C,P) = 3.54 HL; I-C). 12X.14 (d,
'J(C,P) = 2.64 Hz; 0-C), 128.58 (d, 4J(C.P) = 2.31 Hz; m-C). 135.28 ( 8 : p - C ) ,
194.85 (dd, 'J(C,P) =7,24 Hz: 'J(C,W) =125.47 Hz: (.is-CO). 196.97 (d.
'J(C,P) = 35.52 Hz, truns-CO); "P ['Hi NMR: 6 = 40.44 (d. 'J(P.W) =
308.22 Hz).
[a] All spectra in CDCI,, 25°C; ' H N M R : 200 MHr. "C N M R . 50.3 MHz. "P
N M R . 81.0 MHz; the deuterdted solvents were used as internal. 85 %, H,PO, as a n
external standard.
In order to test further the above interpretation of the reaction of the 2H-1,2-azaphosphirene tungsten complex 1 with
2a,b, the reactivity of 1 with respect to the dipolarophile benzaldehyde 6 was investigated. Complex 1 was treated with a
large excess of benzaldehyde (molar ratio 1 :20) in toluene at
45 "C. The formation of the corresponding oxaphosphirane
tungsten complex 7 again points to the phosphanediyl tungsten
complex 3 as the reactive species["] (Scheme 3). Further confir-
an intermediate seems plausible (cf.[']). The other product of
this reaction, p-toluonitrile 5 (Scheme 2), can be identified in the
solution by its characteristic C-N valence band in the IR spectrum."] The 1H-phosphirene tungsten complexes 4a,b show
1
3
7
Scheme 3. 1,7: Ar = p-tolyl. Proposed reaction sequence leading to formation of
the oxaphosphirane tungsten complex 7.a) PhCHO 6itoluene.
2a, b
1
Scheme 2 I , 5 : Ar
=
p-tolyl; und 2a, 4a: R
5
4a,b
= H;
2b, 4b: R
=
Ph.
[*I Dr R. Streubel, DipLChem.
A. Kusenberg, DipLChem. J. Jeske,
Prof. Dr. P. G. Jones
Institut fur Anorgdnische und Analytische Chemie der
Technischen Universitdt
Postfach 3329. D-38023 Braunschweig (FRG)
Telefax: Int. code (531)391-5387
Reactions of 2H-1,2-Azaphosphirene Complexes, Part 2. This work was supported by the Fonds der Chemischen Industrie and by BASF AG, Ludwigshafen. Part 1: [ 5 ] .
+
[**I
Angm.. CliiJm. Inr. Ed. Engl. 1994. 33. No. 23/24
0 VCH
mation of this interpretation is provided by the failure, under
these reaction conditions, to observe the formation of [3 21
cycloaddition products of a phosphorus analogue to a 1,3-dipolar nitrile ylide with benzaldehyde. It is particularly interesting
that the exclusive stereoselective formation of the R S j S R
diastereomer of the oxaphosphirane tungsten complex 7 is observed. This is probably the first example of an effective steric
control of a [2 + I] cycloaddition of a terminal phosphanediyl
complex.[' '1
The 31PN M R spectroscopic data of 7 (Table 1 ) show a significant low-field shift for the resonance of the phosphorus atom
VerlugsgeaeN.tchaft mbH, 0-69451 Weinheim, 1994
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o57o-OR33194j2323-2427 S 10.00+ .ZS/O
2427
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at 6 = 40.44, compared to the only oxaphosphirane complexes
previously known (6 = 2.9 and 3.8).[12] This unusual finding
prompted us to investigate the nature of complex 7 more closely
by a single-crystal X-ray analysis (Fig.
c17n
c12
c9
04
Fig. 1. Structure of compound 7 in the crystal (all H atoms except H6 have been
omitted for clarity). Selected bond lengths [pm] and angles ["I: P I - 0 6 166.8(6),
PI-C6 180.2(7), 06-C6 148.0(9), W-PI 246.2(2), P l - C l 3 179.4(6), C6-C7 149.6(9);
06-Pl-C6 50.3(3), 06-C6-P1 60.1(?). 06-Pl-CI3 107.8(3), C13-Pl-C6 108.6(3).
C6-06-PI 69.6(3), 06-C6-C7 116.8(6). C7-C6-P1 122.8(5).
Figure 1 shows for 7 a three-membered P-C-0 ring system
that is somewhat different from that in the only other known
structure of an oxaphosphirane complex;['21 the P 1 - C 6 bond
is slightly longer, 180.2(7) vs. 177.8(6) pm,[12]as is the P I - 0 6
bond, 166.8(6) vs. 165.7(4) pm,[121 whereas the C - 0 ring
bond length remains constant a t 148.0(9) pm (cf. C - 0
148.0(7) pm1'21).
It is notable that the sum of the angles C6-P 1W1, C13-PI-WI, and C13-PI-C6, 357.8", is close to 360"
(cf.[121).I n view of the very similar bond lengths and angles in
the phosphanediyl tungsten moieties of 1 ['I and 7, any structure;
reactivity relationships in the ring systems of 1 and 7 remain to
be demonstrated.
The cleavage of the 2H-1,2-azaphosphirene ring system in 1
and the interesting comparison with the 2-methylene-2H-azirenes will form the basis of further investigations.
Experimental Procedure
General preparation of4a.b:A solution of 1 (1 mmol) in toluene (3 mL) was treated
under nitrogen at room temperature with phenylacetylene 2a (0.3 g. 2 mmol) or
diphenylacetylene 2b (0.4 g. 2 mmol) and stirred for 2 or 2.5 h. respectively, at 75
C . The pale brown reaction mixtures were evaporated to dryness under reduced
pressure and the products separated by column chromatography on silica ( - 10 'C,
hexane). The eluates were concentrated to about 5 mL under reduced pressure and
cooled to -30 C. The solids thus obtained were washed with a little pentane and
freed from residual solvent under high vacuum
mbar). 4a: Pale yellow powder. yield: 67%. m.p. =104'C (decomp.); 4b: pale yellow powder, yield: 44%.
m.p. =112'C (decomp.).
7: 1 (0.5 g, 0.75 mmol) in toluene (4 mL) was treated with benaaldehyde (1.5 mL,
15 mmol) and stirred for Y h at 45 "C. The yellow-brown solution thus obtained was
evaporated to dryness under reduced pressure. Subsequent column chromatography on silica ( - 30°C. hexane!ether 9:l) afforded 7 as a yellow powder (yield:
56%). Recrysta~~izationfrom pentane a t + 6'C gave pale yellow crystals, yield:
26%. m.p. = 1 1 4 ~ C(decomp.).
Received: August 18, 1994 [Z7244IE]
German version: Anger%,.C ~ ~ 1994.
J W . 106. 2564
2428
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VCH Verlug.~gesel/schuftmhH, 0-69451 W~wdieim,1994
[l] R. Huisgen in 1,3-Dipo/ur Cyclouddition Chemistry (Ed.: A. Padwa), Wiley,
New York, 1984, pp. 1 ff.
121 A. Padwa, A. D. Woolhouse in foniprehmsiw Heterocyclic Chemrsirj. Voi. 7
(Eds.. A. R. Katritzky, C. W. Rees), Pergamon Press, Oxford, 1984. p. 47 and
references therein.
[3] a) K. Banert. M. Hagedorn, Angeii. Chem. 1990,102,90-92; Arzgeri.. Chem. h i .
Ed. Engl. 1990. 29. 103-105; b) K. Banert. M. Hagedorn, E Knozinger, A.
Becker, E.-U. Wurthwein. J. Am. Chem. SOC.1994, 116. 60-62.
[4] Investigations of ring opening of 1H-diazirenes generated as intermediates: a)
X. Creary, A. Sky. G. Phillips. D. Alonso. J. Am. ('hem. SOC.1993. 115,
7584-7592: b) G. Alcarar. A. Baceiredo, M. Nieger. G . Bertrand. rhid. 1994,
116. 2159-2160.
[5] R. Streubel, J. Jeske. P. G. Jones, R. Herbst-Inner, Angeiv. Chem. 1994, 106.
115.117; Angew. Chem. Int. Ed. Engl. 1994, 33, 80-82.
[6] F. Mathey. Angeir. C~IL'JI?.
1987, YY, 285-296; Angew. Chem. Int. Ed. Engl. 1987,
26, 275-286.
[7] IR spectrum of the reaction mixture: tcN= 2224cm-' (CEN).
[8] F. Mathey, Chwi. Res. 1990. 90, 997-2025.
[Y] Selected IR spectroscopic and mass spectrometric data for 4a,b and 7. 4a. I R
(CH,CI,): i. = 2067 s (C=O), 1977 s (C=O), 1953-1912 vs. b (C=O)cm-':
MS (EI, 70eV. '*'W). m/: 616 [ M ' ] ; 4b: IR (CHJI,): t = 2069 s (C=O).
1979 s (C=O), 1954-1918 vs ( C = O ) c m - ' . MS (EI. 70eV, Ia4W): n?;; = 692
[M']. 7: IR (CH,CI,): C = 2073 s (C=O), 1988 s (C=O). 1961-1927 vs. b
(C=O)cm-'. MS (CI. pos, NH,, Ia4W): m;r 620 [ M ' ] . Satisfactory C.H
elemental analysis for 4a,b and 7.
[lo] Interestingly. the first synthesis of an oxaphosphirane derivative was by [2 + I ]
cycloaddition of hexafluoroacetone with an iminophosphane: G.-V.
Roschenthaler, K. Sauerbrey, R. Schmutzler. Chem. Ber. 1978. l f l , 3105-3111.
[ i l l Cf. sterically controlled [1.4] additions: J. M. Alcaraz. J. Svara, F. Mathey,
Noriv. J. Chim. 1986, 10, 321- 326.
[I21 S. Bauer, A. Marinetti. L. Ricard. F. Mathey, A n g e ~ Chem.
.
1990. 102. 11883189, Angeri.. C/7mn. fnl. Ed. En& 1990, 29. 1166-1167.
[13] Crystal structure analysis of 7: C,,H,,NO,PSi,W, triclinic. space group PT,
a = 894.?(3). h = 1070.0(3). c = 1400.0(3) pm. 1 = 87.39(2). /j = 88.62(2).
7 = 68.27(2)", c' = 1.2431(6) nm'. Z = 2.11 = 4.9 mm-', T = - 100°C. A colorless tablet 0.8 x 0.32 x 0.1 mm was mounted in inert oil (type RS 3000, Riedel
de Haen). A Siemens R3 diffractometer with Mo,, radiation was used to
collect 8113 intensities to 20,,, 5 5 - , of which after an absorption correction
(Y-scans) 5200 independent reflections were used for all calculations (program
SHELXL-93: G. M. Sheldrick. University of Gottingen, 1993). The structure
was solved with the heavy atom method and refined anisotropically on F Z . H
atoms were included by using a riding model. The final W R (F') was 0.1 15, with
a conventional R ( F ) 0.043 for 262 parameters and 108 restraints. The maximum residual electron density was 2800 enm-'. Further details of the crystal
structure investigation may be obtained from the Fachinformationszentrum
Karlsruhe. D-76344 Eggensteiii-Leopoldshafen (FRG), on quoting the deposition number CSD-401280.
Porphyrin- Quinone Cyclophanes with Gradually
Varied Donor -Acceptor Distances**
Heinz A. Staab,* Achim Feurer, and Ralf Hauck
Porphyrin -quinone cyclophanes of type 1 represent especially suitable systems for the investigation of photoinduced
electron transfers since the donor and acceptor components are
fixed in well-defined spatial orientations. Whereas all other
structural parameters remained constant, the electron affinity of
the quinone unit and the donor strength of the porphyrin system
were varied over a wide range.[',21 The cyclophane concept
realized in 1 and its doubly bridged analogues[31 was extended to triads of the type porphyrin-quinone( l)-quinone(2)
and porphyrin( l)-porphyrin(2)-quinone for the study of multi[*I
[**I
Prof. Dr. H. A. Staab. Dr. A. Feurer, Dr. R. Hauck
Abteilung Organische Chemie
Max-Planck-lnstitut fur medizinische Forschung
Jahnstrasse 29, D-69120 Heidelberg (FRG)
Telefax: Int. code + (6221)486-219
Photoinduced Electron Transfer in Porphyrin-Quinone Cyclophanes, Part 13.
Part 12: [4b].
+
0570-0833/94/2323-242X $ 10.00 .25;0
Angerv. Chem. lnt. Ed. Engl. 1994. 33. No. 23/24
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