Organometallics 1996, 14, 4319-4324
4319
Stereoselective Ring Expansion of 3-Vinyl-1-cyclopropenes To Give (q5-Cyclopentadienyl)rutheniumand (q4-Cyc1ohexadienone)ironComplexes. Exclusion of Planar Metallacyclohexadiene Intermediates and Relevance to the Dtitz Reaction Russell P. Hughes,*$+Hernando A. Trujillo,l and Andre J. Gauri Burke Chemistry Laboratory, Dartmouth College, Hanover, New Hampshire 03755-3564 Received May 1, 1995@
trans-3-(~-Deuteriovinyl)-1,2,3-triphenyl-l-cyclopropene, 15, reacts with Fe2(CO)g to give the 2,4-~yclohexadieneonecomplex 16, as a single isotopomer. The location of deuterium in the endo-position was confirmed by comparison of lH NMR spectra of 16 with its isotopomer 10 and by conversion of both isotopomers to their bis(trimethy1phosphine) derivatives 17a,b. NOE experiments on 17a show a positive interaction between the endo-H and PMe3; this resonance is missing in 17b. Similarly, 15 reacts with [Ru(C5Mes)C1]4 or [Ru(CsMes)(MeCN)31+BF4-to give only a single isotopomeric ruthenocene 9b, containing no deuterium. Formation of single isotopomers in each reaction excludes any access to a planar metallacyclohexadiene, or any species with a symmetry plane bisecting the CHD group, as a n intermediate or transition state along the reaction pathway. Internally consistent mechanisms for formation of the six- and five-membered rings are proposed to account for the stereochemical features of these and related reactions. Analogies are drawn between these reactions and those pathways proposed for the synthetically useful Dotz reaction for the synthesis of five- and six-membered organic rings. Introduction Numerous examples of the ring expansion of 3-vinyl1-cyclopropenes to give five- and six-membered rings exist in the literature. Initial observations of thermal and photochemical formation of cyclopentadienes and indenes from vinylcyclopropenes2 were followed by transition metal mediated preparation of cyclopentadienes and cyclopentadienyl c ~ m p l e x e s ~and, - ~ with incorporation of a molecule of CO, phenols and cyclohexadienone~.~J~ The reaction manifold leading t o these organic rings is similar to the synthetically useful Dotz reaction, in which five- and six-membered rings are formed from alkynes and group 6 Fischer carbene
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[email protected]. Abstract published in Advance ACS Abstracts, August 15, 1995. (1)American Chemical Society, Division of Organic Chemistry Fellow, 1990-1991; sponsored by the American Cyanamid Co. (2) Padwa, A. Org. Photochem. 1979,4 , 261-326 and references therein. Breslow, R. In Molecular Rearrangements; (de Mayo, P., Ed.; Wiley: New York, 1963; Part 1,p 236. Zimmerman, H. E.; Hovey, M.C. J . Org. Chem. 1979,44, 2331-2345. Zimmerman, H. E.; Kreil, K. J. J . Org. Chem. 1982,47, 2060-2075. Zimmerman, H. E.; Fleming, S. A. J. Org. Chem. 1985,50,2539-2551. (3) Grabowski, N. A,; Hughes, R. P.; Jaynes, B. S.; Rheingold, A. L. J . Chem. Soc., Chem. Commun. 1986,1694-1695. (4) Egan, J. W., Jr.; Hughes, R. P.; Rheingold, A. L. Organometallics 1987,6,1578. (5) Donovan, B. T.; Egan, J. W., Jr.; Hughes, R. P.; Spara, P. P.; Truiillo. H. A.: Rheineold. A. L. Isr. J. Chem. 1990.30.351. (6) Hughes,'R. P.; Robinson, D. J. Organometallks 1989,8, 1015. (7) Donovan, B. T.; Hughes, R. P.; Trujillo, H. A. J . A m . Chem. SOC. 1990.112.7076. (8j Donovan, B. T.; Hughes, R. P.; Kowalski, A. S.; Trujillo, H. A.; Rheingold, A. L. Organometallics 1993,12,1038. (9) Semmelhack, M. F.; Ho, S.; Steigerwald, M.; Lee, M. C. J.Am. Chem. SOC.1987,109,4397. Semmelhack, M. F.; Ho, S.; Cohen, D.; Steigerwald, M.; Lee, M. C.; Lee, G.; Gilbert, A. M.; Wulff, W. D.; Ball, R. G. J . Am. Chem. SOC.1994,116,7108. (10) Cho, S. H.; Liebeskind L. S. J. Org. Chem. 1987,52,2631. @
0276-7333l95/2314-4319$09.0~l0
complexes.ll A mechanism for the generic Dotz reaction is shown in Scheme l.llb The unsaturated group bound t o the carbene center can be a vinyl group, as shown, in which case monocyclic products are obtained, or part of a phenyl ring, leading eventually t o benzannulated products. The first carbon-carbon bond-forming step is thought to involve formation of metallacyclobutene l a or the valence isomeric vinylcarbene lb;calculations favor the latter.12 At this stage the choice of ring size is made. Incorporation of CO can occur, in a reaction which is known for vinylcarbene complexes, t o afford a vinylketene intermediate 2 which can then cyclize to give a cyclohexadienone complex. Tautomerization and decomplexationfrom the metal center eventually affords a phenolic ring system.13 However, a number of potentially significant equilibria involving intermediates la and lb are possible. These may precede CO incorporation or may divert the reaction along another pathway to give a cyclopentadiene-basedring system. Coordination of the vinyl group of l a or lb affords intermediates (11)(a)Dotz, K. H.Angew. Chem., Int. Ed. Engl. 1984,23,587. For a detailed discussion, and leading references, see: Bos, M. E.; Wulff, W. D.; Miller, R. A.; Chamberlin, S.; Brandvold, T. A. J . Am. Chem. SOC.1991,113, 9293. Other recent references include: Harvey, D. F.; Grenzer, E. M.; Gantzel, P. K. J. Am. Chem. SOC.1994,116,6719. Barluenga, J.; Aznar, F.; Martin, A.; Garcia-Granda, S.;Perez-Carreno, E. J . Am. Chem. SOC.1994,116,11191. Gross, M.F.; Finn, M. G. J . Am. Chem. SOC.1994,116,10921. (b) For recent detailed mechanistic discussion see: Wulff, W. D.; Bax, B. M.; Brandvold, T. A.; Chan, K. S.; Gilbert, A. M.; Hsung, R. P.; Mitchell, J.;Clardy, J . Organometallics 1994,13,102. (12) For calculations on metallacyclobutene and vinylcarbene isomers, see: Hofmann, P.; Hammerle, M.; Unfied, G. New J . Chem. 1991, 15,769. (13) A nontautomerized cyclohexadienone complex has recently been isolated.llb
0 1995 American Chemical Society
Hughes et al.
4320 Organometallics, Vol. 14,No. 9,1995
Scheme 1
la
tl
lb
tl
R'
I \
Yb
3a
4a
'R
4b
"
Scheme 2
phd
/r I
Ph
I
Ph
Ph
RR&R
R
Ph
5
9 a.
R=H b. R = M e
10
"FI~CI(PM~~)~"
CI
A
,Ph
7 3a and 3b. From 3a,the metallacyclohexadiene intermediate 4a can be accessed as shown, and formation of five-memberedrings from such an intermediate is often shown as a direct coupling of the sp3 and sp2 carbon centers. While the usual route into the Dotz reaction involves initial carbon-carbon bond formation from the metalcarbene complex and the alkyne, an alternative entry into the same reaction manifold can be afforded by direct reaction of a 3-vinyl-1-cyclopropene as shown in In our studies of the reactions of vinylScheme l.9J4 cyclopropenes with transition metal centers, we have been have been able to isolate species with structures (14)The Dotz reaction manifold can be entered at a variety of other points. See: Huffman, M. A,; Liebeskind, L. S.; Pennington, W. T. Organometallics, 1992,11, 255.
- PMe3
6 analogous to suggested intermediates in the Dotz reaction and to study their ~ h e m i s t r y . ~Some - ~ representative reactions of triphenylvinylcyclopropene 5 with transition metal centers are shown in Scheme 2. Reaction of 5 with the [RhCl(PMe&I fragment affords the pentadienediyl complex 6, structurally analogous to intermediate 3a; variable-temperature NMR studies show unambiguously that, while 6 is the ground state structure, it is in rapid equilibrium with the metallacyclohexadiene species 7 on the NMR time scale and can be converted to an acetylacetonato analogue containing a stable metallacyclohexadienering.4 On heating, 6 loses PMe3 and presumably undergoes cyclization to a cyclopentadiene ligand followed by endo-H migration to the metal to give 8 . A similar reaction is observed on reaction of 5 with the [RuCl(C5R5)1frag-
Organometallics, Vol. 14, No. 9, 1995 4321
Ring Expansion of 3-Vinyl-1-cyclopropenes
A
'Bu
L = CI (dlmer)
11
14 position, showing that the ring closure to give the ments (R = H, Me), although fewer intermediates are cyclopentadiene neither requires nor even samples a observed.6 These reactions afford complexes 9 presumplanar metallacyclohexadiene intermediatee7 Correably via a sequence of events analogous t o those in the sponding heating of the dimeric complex 12a affords the formation of 8 except that eventual elimination of HCl rearranged cyclopentadiene complex 14, by analogous from the metal occurs to give the very stable ruclosure of the ring to give endo-D followed by migration thenocene structure. The reaction of 5 with [Fez(C0)9] of D to the 16-electron Rh center and back to the ring, affords only an y4-cyclohexadienone complex 10, the as shown;s this latter pathway is blocked in the correproduct of CO inc~rporation;~ Semmelhack has shown sponding Welectron complex 13.7 These stereochemthat the same vinylcyclopropene reacts with [Mo(CO)6] to afford triphenylphenol via analogous ~ h e m i s t r y . ~ J ~ ical results indicate that ring closure is probably best considered to occur by intramolecular addition of the Therefore, these transition metal promoted reactions of Rh-C a-bond to the Rh-olefin bond' and that simple vinylcyclopropenes provide reasonable model systems reductive coupling from a metallacyclohexadiene is for the formation of five- and six-membered rings in the rigorously excluded in this sterically biased system. Dotz reaction and afford opportunities to evaluate possible mechanisms for ring formation in the latter. Clearly the reactions involving 11 are sterically biased Notably because the organic ring remains ligated to the enough to completely exclude access t o a metallacyclometal, these reactions afford an opportunity to probe hexadiene intermediate and demonstrate that such a the stereochemistry of the ring formation reaction, species is not necessary for formation of a fiveunlike the Dotz reaction itself, in which any stereomembered ring. These results do not exclude metallachemical information may be lost by decomplexation and cyclohexadienes as accessible intermediates in less tautomerization of the organic product.11J3 biased systems, as demonstrated by the facility with In order to probe whether a metallacyclohexadiene which the rhodium complex 6 accesses metallacyclointermediate was necessarily required for cyclopentahexadiene 7 on the NMR time scale.4 We now report diene ring formation, we previously investigated the the results of a similar mechanistic interrogation of the reactions of the selectively deuterium-labeled tri-tertother reactions represented in Scheme 2 to see whether butylvinylcyclopropene 11 with Rh(1) species, as shown metallacyclohexadienes were sampled along reaction in Scheme 3. The reaction of 11 with [RhCl(C2H4)& pathways that afford cyclopentadienyl or cyclohexadiafforded the dimeric pentadienediyl complex 12a, in enone ligands. which the deuterium is exclusively in the syn-position shown. Isomerization t o the anti-D isotopomer is Results and Discussion extremely slow, providing an unambiguous demonstraIn order to test for the presence of planar metallacytion that a planar metallacyclohexadiene analogous t o clohexadiene intermediates in these reactions, the 7 (or 4a) is a very high energy intermediate in this selectively deuterated 1,2,3-triphenyl-3-vinyl-l-vinyl~ y s t e m .The ~ major contribution to the instability of cyclopropene (15) was required. Attempts to prepare this particular metallacyclohexadiene arises from the this compound in a manner analogous to that used for steric problems associated with locating three tert-butyl the preparation of 11,5by coupling of the triphenylcygroups on contiguous carbon atoms in a planar sixclopropenyl cation with trans-(CHD=CHLi), failed. membered ring. Complex 12a was converted to its However, in situ conversion of the vinyllithium reagent mononuclear indenyl analogue 12b without scrambling to its magnesium analogue using MgBr2, followed by of deuterium. On heating of 12b, the cyclopentadiene coupling of the resultant trans-(CHDeCHMgBr) with complex 13 was formed, with D exclusively in the endo-
Hughes et al.
4322 Organometallics, Vol. 14,No.9,1995
Table 1. Coupling Constants and NOES to the CH2 Protons of 10 and 17a 17a 10
3J~H" 4.36 1.9
endo exo
3 J ~ ~ a
3.v 1.8
NOE to PMe3
JHP" n.0.d
+
6.0
n.0.d
a in Hz. This resonance is absent in the deuterated compound 16. This resonance is absent in the deuterated compound 17b.
n.0.: not observed.
the triphenylcyclopropenyl cation, afforded the required 15 in 50%yield.15 The lH and :!H(lH} NMR spectra of this compound confirm that the deuterium is located exclusively in the position shown. Treatment of trans-deuterated vinylcyclopropene 15 with [Fez(C0)91 afforded the single endo-deuterated isotopomer 16. The location of the deuterium on the endo face of the cyclohexadienonering in 16 is indicated by the following observations. Faller has noted that vicinal lH NMR coupling constants are a reliable means to assign the resonances of the exo- and endo-hydrogens of a CH:! group in coordinated cyclohexadienes and cyclopentadienes: the pucker of the coordinated ring reduces the vicinal coupling to the ex0 hydrogen in a Karplus fashion, while the coupling to the endo hydrogen is increased.16 Examination of the vicinal coupling constants to the two geminal protons of 10 and 16 (Table 1) indicates that the resonance which disappears on deuteration is endo. To confirm this assignment, both isotopomers 10 and 16 were converted to the corresponding bis(trimethy1phosphine) derivatives 17a,b. Although the vicinal proton coupling constants for the exo- and endo-hydrogens of 17a did not differ significantly from those in 10, the observation of phosphorushydrogen coupling to only one geminal proton identified that proton as Hexo;17 comparison with the corresponding spectrum of 17b illustrates that, in this complex, deuteration is observed in the position lacking an observable JHP,i.e. the endo position. Finally, the NOE difference spectrum of 17a showed an interaction between the methyl groups of a phosphine and only one of the geminal hydrogens, identifying its resonance as that for H e n d o ; this is the resonance missing in the spectrum of 17b. The combined evidence of these NMR studies unambiguously locates the deuterium in the endo position of 16 as shown. Since any reaction pathway involving a metallacyclohexadiene, or indeed any other species in which a plane of symmetry bisects the CHD group, must result in scrambling of the deuterium label between ex0 and endo positions in the final cyclohexadienone ring, observation of only one product isotopomer clearly demonstrates that none of the pathways to CO incorporation and subsequent ring closure can sample such a sym(15) A similar procedure has been used to afford other isotopically labeled vinylcyclopropenes: Hughes, R. P.; Trujillo, H. A,; Rheingold, A. L. J . A m . Chem. SOC.1993,115,1583. (16) Faller, J. W. Inorg. Chem. 1980,19,2857.See also: Szajek, L. P.; Shapley, J. R. Organometallics 1991,10,2512. Bailey, N.A,; Blunt, E. H.; Fairhurst, G.; White, C. J. Chem. SOC.,Dalton Trans. 1980,829. Schrock, R.R.;Osborn, J. A.Inorg. Chem. 1970,9,2339. Birch, A.J.; Cross, P. E.; White, D. A. J. Chem. SOC.A 1968,332. Birch, A. J.; Chamberlain, K. B.; Hass, M. A.; Thompson, D. J. J. Chem Soc., Perkins Trans. 1973,1882. Birch, A.J.;Chamberlain, K. B.; Thompson, D. J. J . Chem. SOC.,Perkins Trans. 1973,1900. (17)Indirect JHP couplings appear to have a strong dependence on bond angles. See, for example, ref 15 and: Mavel, G. Annu. Rep. NMR Spectrosc. 1973,5B, 30.
Scheme 4 15 + F%(CO)Q
Ph
18a
lga
Ph
1
I
ti
H
Il
I Ph
lab
lgb
Dh
16
/
metric intermediate or transition state. With this constraint in mind, a reasonable mechanism is shown in Scheme 4. Insertion of the metal into the cyclopropene ring affords metallacyclobutene intermediate Ma, which may be in equilibrium with its vinylcarbene valence tautomer 18b. Incorporation of CO via an insertion reaction of Ma affords the corresponding species 19a. It is straightforward to envisage ring closure from 19a by migratory insertion reaction of the iron-acyl bond to the coordinated deuteriovinyl group as shown. In order to maintain orbital overlap, such an insertion must result in the CHD terminus rotating as shown, with the inevitable result that deuterium is located in the endo-position of the resultant ring. This provides a pathway for formation of the six-membered ring consistent with that proposed for five-membered cyclopentadiene ring formation in the rhodium-based system shown in Scheme 3.7,8 An alternative picture
Organometallics, Vol. 14, No. 9, 1995 4323
Ring Expansion of 3-Vinyl-1-cyclopropenes
Scheme 6 15 + Ru(CSMeS)+
/
H
These results delineate a consistent picture of the stereochemistry of this kind of ring closure reaction by excluding planar metallacyclohexadiene intermediates en route to formation of either five- or six-membered organic rings. By analogy, they demonstrate unambiguously that such intermediates are not required in the Dotz reaction. Taken in conjunction with previous r e s ~ l t s ,they ~ , ~also suggest that reductive elimination or coupling reactions involving allylic ligands occur from the v3-allylic form rather than from the #-allylic isomer.
H
MB'
20
Ph
Dh
Experimental Section
1
\I+D i
It
Me Me Me
Me
21
I
Ph
Oh
ph@-H Ph
ph&H
I
- D+
+n
Me
Me
of the ring closing step derives from consideration of a butadienylcarbene intermediate 18b;ll CO insertion would afford 19b, electrocyclic closure of which would also have to be stereospecific with rotation of the CHD group of the uncoordinated olefin in the s a m e sense required to give endo-deuterium. Such a pathway is not available for the five-membered ring formation discussed above or that encountered in the system discussed below. We next treated 15 with two different sources of the [Ru(CsMes)]+ fragment, the tetrameric [RuCl(C5Me5)14 a n d t h e monomeric [Ru(CsMes)(MeCN)#. In each case the product obtained was the previously characterized ruthenocene 9b6in which no trace of deuterium above natural abundance w a s observed by 2H(1H} NMR spectroscopy. T h e proposed mechanism is shown in Scheme 5. Ring closure from intermediate 20 to give 21 places deuterium selectively in the endo-position, from which it can transfer t o ruthenium to give 22, a n d thence be eliminated as D+. This pathway is stereochemically consistent with all the previous examples in r h ~ d i u mand ~ , ~iron (vide s u p r a ) based chemistry. We specifically discount the possibility that a different stereochemistry for ring closure occurs to give the exo-D isotopomer of 21 followed by loss of exo-D+. Such a pathway would violate the principle of microscopic reversibility; reversible protonation of ruthenocene has been shown unambiguously to occur, not via exo-attack at a cyclopentadienyl ring b u t exclusively at the ruthenium center with no subsequent transfer from protonated ruthenium to a cyclopentadienyl ring.18
General Procedures. All reactions were performed in oven-dried glassware, using standard Schlenk techniques, under an atmosphere of nitrogen which had been deoxygenated over BASF catalyst and dried over Aquasorb. Hydrocarbon reaction solvents and ether were distilled under nitrogen from benzophenone ketyl; halogenated solvents were distilled from 4 A molecular sieves. Aromatic and unsaturated components of 35-65 "C petroleum ether were removed before distillation by prolonged standing over HzS04 (concentrated) followed by washing with NazC03 (10% aqueous). 'H (300 MHz), 2H{'H} (46.1 MHz), 13C{lH)(75.4MHz), and 31P(1H}(121 MHz) NMR spectra were recorded on a Varian XL-300 Spectrometer at 25 "C. Chemical shifts are reported as ppm downfield of either TMS (lH, 2H, and 13C NMR, referenced to the solvent) or external 85% (31PNMR). Coupling constants are reported in Hz. IR spectra were recorded on a Bio-Rad Digilab FTSdO Fourier transform infrared spectrophotometer. Melting points of samples in capillaries sealed under vacuum were obtained using an Electrothermal or a Thomas Hoover device and are uncorrected. Elemental analyses were performed by Spang (Eagle Harbor, MI). Trimethylphosphine was purchased from Strem. Deuterioacetic acid was obtained from Aldrich. [Fez(C0)91,l9triphtruns-bis(tributylstannyl)ethylene,2l enylvinylcyclopropene 6,z0 [R~(C5Me5)01~-C1)]4,~~ [RU(C~M~~)(NCM~)~]BF~,~~ triphenylcyclopropenyl tetrafluorob~rate,~~ and MgBrdether complexz5 were prepared by literature routes. truns-3-(B-Deuteriovinyl)-l,2,3-triphenyl-l-cyclopropene, 15. n-Butyl lithium (4.6 mL of 2.81 M hexanes solution, 13 mmol, 1 equiv) was added to a -78 "C solution of trunsbis(tributylstanny1)ethylene(7.0 mL, 13 mmol, 1.0 equiv) in THF (90 mL). The resulting pale yellow solution was stirred 1 h at -78 "C and then quenched with DOAc (0.75 mL, 13 mmol, 1 equiv) and warmed to room temperature. The colorless mixture was cooled back to -78 "C and treated with a second equivalent of n-BuLi (4.6 mL, 13 mmol). After being stirred for 1h a t -78 "C, the yellow mixture was treated with MgBrdether complex (6.0 mL, 16 mmol, 1.2 equiv) and allowed to warm to room temperature, giving a clear yellow solution. The solution was added to a -78 "C slurry of 1,2,3-triphenylcyclopropenyl bromide (2.26 g, 6.56 mmol, 0.5 equiv) in THF (90 mL), warmed to room temperature, and stirred 8 h to give a pale yellow solution. The reaction was quenched with aqueous ammonium chloride (100 mL, 20%), and the layers were separated. The aqueous layer was extracted with ether (18)Mueller-Westerhoff, U.T.; Haas, T. J.;Swiegers, G.F.; Leipert, T. K. J. Organomet. Chem. 1994,472,229. (19)Braye, E. H.; Hiibel, W. Inorg. Synth. 1966,8, 178. (20)(a) Padwa, A.;Blacklock, T. J.;Getman, D.; Hatanaka, N.; Loza, R. J. Org. Chem. 1978,43,1481.(b) Zimmerman, H. E.; Aasen, S. M. J. Org. Chem. 1978,43,1493. (21)(a) Corey, E.J.;Wollenberg, R. H. J. Org. Chem. 1975,40,3788. (b) Bottaro, J. C.; Hanson, R. N.; Seitz, D. E. J. Org. Chem. 1981,46, 5221. (22) Fagan, P. J.; Ward, M. D.; Calabrese, J. C. J. Am. Chem. SOC. 1989,111, 1698. (23)The BF4 salt was prepared by substituting AgBF4 for AgOTf in Fagan's preparation of the triflate.22 (24)Breslow, R.; Chang, H. W. J. A m . Chem. SOC. 1961,83,2367. (25)Maercker, A,; Roberts, J. D. J.Am. Chem. SOC.1966,88,1742.
4324 Organometallics, Vol. 14, No. 9, 1995
Hughes et al.
'H NMR (CsDs): 6 6.72-7.71 (m, 15H, Ph), 2.71 (ddd, l H , JHH (3 x 50 mL); the combined organic layers were washed with = 18.5, 1.8,JHP = 6.0, Hex,), 2.52 (dd, l H , JHH = 18.5, 3.7, water (3 x 50 mL) and brine (2 x 10 mL). Drying over MgS04 and evaporation left a yellow oil, which was purified by flash Hendo),2.38 (dddd, lH, JHH = 3.6, 1.8, JHP = 9.6,0.5,CHI, 1.34 (d, 9H,JHP = 7.5, PMed, 0.52 (d, 9H, JHP = 8.1, PMe3). 31Pchromatography (Si02,5 x 16 cm). Elution with hexanes (2.5 {'H} NMR (CsD6): 6 25.68 (d, J p p = 22.3, PMes), 14.35 (d, J p p L) gave Bu4Sn followed by the desired vinylcyclopropene (1.00 = 22.1, PMe3). IR (Cc4, cm'): uco = 1890 vs, 1653 m. g, 50%) as soapy white crystals after evaporation. 'H NMR The deuterated isotopomer 17b was prepared similarly from (CsD.5): 6 6.98-7.68 (m, 15 H, Ph), 6.70 (d, lH, J = 17.2, Ha), 16 and trimethylphosphine. 'H NMR: identical to that of the 5.32 (d, l H , J = 17.3, Heis). 2H{'H} NMR (CsHs): 6 5.14 (br, protic material above except for the absence of the 6 2.52 peak Dtrans). and the associated 18.5 and 3.6 Hz couplings. 2H(1H}NMR [2-5-rp(2,3,4-Triphenyl-2,4-cyclohexadienone)] tricarbonyliron,10. A suspension of Fez(C0)~(0.70 g, 1.9 mmol, (CsDs): 6 2.52 (br, Dendo).31P(1H}NMR (C&) and IR (UCO; C c 4 ) were identical t o those of the protic material above. 1.1 equiv) and triphenylvinylcyclopropene 5 (0.50 g, 1.7 mmol) (~6-Pentamethylcyclopentadienyl)(;rl6-l,2,3-t~phenylin ether (30 mL) was stirred for 7 h and then filtered through cyclopentadienyl)ruthenium,9b. (a)From [Ru(C&Ies)Celite and concentrated. The mixture was applied to a (NCMe)slBF4.Triphenylvinylcyclopropene 5 (53 mg, 0.18 chromatography column (SiO2, 1.7 x 9 cm, 20 "C) under mmol, 1.1 equiv) was added t o a greenish-yellow solution of nitrogen. A yellow band eluted with ether (30 mL) and was [Ru(C5Mes)(NCMe)31BF4(73 mg, 0.16 mmol) in CHzCl2 (10 mL) evaporated t o dryness. Recrystallization of the residue from a t ambient temperature. The resulting rust-colored solution ether gave 10 (371 mg, 47%) as yellow needles. Mp: 146was stirred overnight, during which time its color faded to 149 "C, dec. Calcd for C27HlgFe04: 70.15, C; 3.92, H. Found: amber. The residue left on evaporation was extracted with 69.98, C; 4.01, H. lH NMR (CDC13): 6 7.0-6.1 (m, 15H, Ph), petroleum ether (3 x 15 mL); evaporation of the yellow extracts 3.05 (dd, lH, JHH = 4.0, 1.8, =CHI, 2.70 (dd, l H , JHH = 18.9, left 9b as a white solid (71 mg, 82%). The 'H NMR (CDC13) of = 18.9, 1.8, H e d . 13C(1H)NMR 4.0, H e n d o ) , 2.30 (dd, lH, JHH the product was identical to that reported in the literature:66 (CDC13): 6 209.6 (Fe-CO), 194.9 (C=O), 137.2-126.0 (Ph), 7.00-7.29 (m, 15H, Ph), 4.62 (s, 2H, HcJ, 1.67 (s, 15 H, Me). 111.2 (CPh), 104.5 (CPh), 84.2 (CPh), 51.4 (CHI, 36.2 ( C H 2 ) . The analogous reaction of deuterated vinylcyclopropene 15 IR (KBr, cm-l): uco = 2060 vs, 2005 vs, 1993 vs, 1690 m. produced an identical product for which no residual deuterium The endo-deuterated isotopomer 16 was prepared as dewas detectable by 'H or 2H NMR. scribed for the protic compound above, using deuterated (b)From [Ru(C&Ie5)ClIr.Deuterated 15 (92 mg, 0.31 triphenylvinylcyclopropene 15. 'H NMR (CsDs): 6 7.02-6.08 mmol, 1.0 equiv) was added to a solution of [Ru(C5Me5)C1]4 (m, 15H, Ph), 3.07 (d, lH, JHH = 1.9, HJ, 2.29 (br, l H , Hex& (84 mg, 0.31 mmol Ru) in CHzClz (15 mL). The mixture was 2H{'H} NMR (C&): 6 2.66 (br, Dendo).IR (ccl4, cm-'1: uco stirred overnight and evaporated, and the residue was ex= 2060 vs, 2000 vs, 1992 vs, 1683 m. [2-5-~-(2,3,4-Triphenyl-2,4-cyclohexadienone)lcarbo- tracted with petroleum ether. Removal of solvent from the yellow extracts left 9b as a yellow oil which solidified on the nylbis(trimethylphosphine)iron, 17a. A solution of 10 (26 addition of ether and subsequent evaporation (147 mg, 89%). mg, 56 pmol) and trimethylphosphine (23 pL, 0.27 mmol, 5 The 'H NMR spectrum of the product was identical to that equiv) in benzene (10 mL) was irradiated for 30 min (Canradprepared from [Ru(CsMes)(NCMe)3]BF4;no residual deuterium Hanovia 450 W medium-pressure Hg-arc lamp, Pyrex filter, was detected by 'H or 2H(1H}NMR. 10 "C), over which time the yellow solution darkened. The mixture was freeze-dried, dissolved in a minimum of ether, and purified by chromatography (1 x 12 cm Si02, under Acknowledgment. We are grateful to the National nitrogen, 20 "C). The bis(phosphine) complex eluted with ether Science Foundation for generous financial support of (20 mL) as an orange band, which was evaporated to give 17a this work and to Johnson Matthey AesarlAlfa for a loan (12 mg, 39%). A n analytical sample was recrystallized by slow of ruthenium chloride. evaporation of ether. Mp: 120 "C, dec 130 "C. Calcd for OM9503149 C31H36Fe02P2: 66.68, C; 6.50, H. Found: 66.68, C; 6.51, H.
