Efficient synthetic routes to terminal γ-keto-alkynes and unsaturated cyclic carbene complexes based on regio- and diastereoselective nucleophilic additions of enolates on ruthenium(II) indenyl allenylidenes

Organometallics 2001, 20, 3175-3189

3175

Efficien t Syn th etic Rou tes to Ter m in a l γ-Keto-Alk yn es

a n d Un sa tu r a ted Cyclic Ca r ben e Com p lexes Ba sed on

Regio- a n d Dia ster eoselective Nu cleop h ilic Ad d ition s of

En ola tes on Ru th en iu m (II) In d en yl Allen ylid en es

Victorio Cadierno, Salvador Conejero, M. Pilar Gamasa, and J ose´ Gimeno*

Departamento de Qu´ımica Orga´nica e Inorga´nica, Instituto Universitario de Qu´ımica

Organometa´lica “Enrique Moles” (Unidad Asociada al CSIC), Facultad de Qu´ımica,

Universidad de Oviedo, E-33071 Oviedo, Spain

Enrique Pe´rez-Carren˜o and Santiago Garc´ıa-Granda

Departamento de Qu´ımica Fı´sica y Anal´ıtica, Facultad de Qu´ımica, Universidad de Oviedo,

E-33071 Oviedo, Spain

Received March 27, 2001

Ruthenium(II) indenyl allenylidene complexes [Ru{dCdCdC(R¹)Ph}(η⁵-C₉H₇)(PPh₃)₂][PF₆]

i

(R¹) Ph (1), H (2)) regioselectively react with lithium enolates LiCH₂COR²(R²) Ph, Pr,

Me, Fc, (E)-CHdCHPh) at the C_γatom to yield the neutral σ-alkynyl derivatives [Ru{Ct

CC(R¹)Ph(CH₂COR²)}(η⁵-C₉H₇)(PPh₃)₂] (3a -e, 4a -d ). Protonation of 3a -e and 4a -d with

HBF₄‚Et₂O affords the cationic vinylidene derivatives [Ru{dCdC(H)C(R¹)Ph(CH₂COR²)}-

(η⁵-C₉H₇)(PPh₃)₂][BF₄] (5a -e, 6a -d ), which can be easily demetalated, by treatment with

acetonitrile, to yield the terminal γ-keto-substituted alkynes HCtCC(R¹)Ph(CH₂COR²) (7a -

e, 8a -d ) and the nitrile complex [Ru(NtCMe)(η⁵-C₉H₇)(PPh₃)₂][BF₄] (9). The addition of

i

lithium enolates LiCH₂COR (R ) Ph, Pr, Me) on the optically active allenylidene complex

[Ru{dCdCdC(C₉H₁₆)}(η⁵-C₉H₇)(PPh₃)₂][PF₆] (12; C(C₉H₁₆) ) (1R)-1,3,3-trimethylbicyclo-

[2.2.1]hept-2-ylidene) proceeds in a regio- and diastereoselective manner, affording σ-alkynyl

derivatives [Ru{CtCC(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(PPh₃)₂] (13a -c). The X-ray crystal struc-

ture of 13b shows that these enolate additions take place on the less sterically congested

exo face of the allenylidene chain. Chiral alkynes HCtCC(C₉H₁₆)(CH₂COR) (15a -c) have

been also prepared from 13a -c via initial protonation with HBF₄‚Et₂O and subsequent

treatment of the resulting vinylidenes 14a -c with acetonitrile. Cyclic alkenyl derivatives

i

[Ru{CdCHC(R¹)(R²)CHdC(R³)O}(η⁵-C₉H₇)(PPh₃)₂] (R¹) R²) Ph, R³) Ph (18a ), Pr (18b);

R¹R²) C₉H₁₆, R³) Ph (20)) have been obtained by treatment of dichloromethane solutions

of σ-alkynyl complexes 3a ,b and 13a with catalytic amounts of AlCl₃at room temperature.

Protonation of these species affords the cyclic carbenes [Ru{dCCH₂C(R¹)(R²)CHdC(R³)O}-

(η⁵-C₉H₇)(PPh₃)₂][BF₄] (19a ,b, 21).

In tr od u ction

vealing the great potential of these species to promote

novel C-C and C-heteroatom coupling reactions.¹

Moreover, it is now well-established that the regio-

selectivity of these nucleophilic additions is strongly

dependent on the metallic fragment.¹In general,

allenylidene groups attached to bulky and/or electron-

rich metallic fragments are unreactive toward weak

nucleophiles but react with strong nucleophiles which

As a part of the continuous interest in the chemistry

of carbene complexes, allenylidene derivatives [M]dCd

CdCR₂have attracted a great deal of attention in recent

years due to their versatile reactivity.¹Theoretical

studies clearly indicate that the C_Rand C_γcarbon atoms

of the allenylidene chain are electrophilic centers, while

the C_âis a nucleophilic site.²Nucleophilic attacks

dominate the reactivity of allenylidene complexes, re-

(2) (a) Schilling, B. E. R.; Hoffman, R.; Lichtenberger, D. L. J . Am.

Chem. Soc. 1979, 101, 585. (b) Berke, H.; Huttner, G.; von Seyerl, J .

Z. Naturforsch. 1981, 36B, 1277. (c) Pe´rez-Carren˜o, E. Doctoral Thesis,

University of Oviedo, 1996. (d) Esteruelas, M. A.; Go´mez, A. V.; Lo´pez,

A. M.; Modrego, J .; On˜ate, E. Organometallics 1997, 16, 5826. (e) Xia,

H. P.; Ng, W. S.; Ye, J . S.; Li, X.-Y.; Wong, W. T.; Lin, Z.; Yang, C.;

J ia, G. Organometallics 1999, 18, 4552. (f) Re, N.; Sgamellotti, A.;

Floriani, C. Organometallics 2000, 19, 1115. (g) Baya, M.; Crochet,

P.; Esteruelas, M. A.; Gutie´rrez-Puebla, E.; Lo´pez, A. M.; Modrego, J .;

On˜ate, E.; Vela, N. Organometallics 2000, 19, 2585.

* To whom correspondence should be addressed. E-mail: jgh@

sauron.quimica.uniovi.es.

(1) For comprehensive reviews on the synthesis and reactivity of

allenylidene complexes see: (a) Bruce, M. I. Chem. Rev. 1991, 91, 197.

(b) Werner, H. Chem. Commun. 1997, 903. (c) Bruce, M. I. Chem. Rev.

1998, 98, 2797. (d) Touchard, D.; Dixneuf, P. H. Coord. Chem. Rev.

1998, 178-180, 409. (e) Cadierno, V.; Gamasa, M. P.; Gimeno, J . Eur.

J . Inorg. Chem. 2001, 571.

Publication on Web 06/12/2001

3176 Organometallics, Vol. 20, No. 14, 2001

Cadierno et al.

Ch a r t 1

are added regioselectively at the C_γatom, leading to the

alkynyl species [M]-CtCCR₂(Nu).³In contrast, the

presence of metallic units bearing less sterically de-

manding and/or more π-electron-withdrawing ligands

show a marked ability to add both soft and hard

nucleophiles at the C_Ratom.⁴

We have described an extensive series of allenylidene

complexes containing η⁵-indenyl-ruthenium(II) frag-

ments and have investigated their influence on the

reactivity of the cumulenic chain.^3h,5Thus, we have

shown that those allenylidene groups stabilized by the

electron-rich [Ru(η⁵-C₉H₇)(PPh₃)₂]⁺moiety are able to

add regioselectively a large variety of neutral and

anionic nucleophiles at the C_γatom to afford the

functionalized σ-alkynyl derivatives [Ru{CtCCR¹R²-

(Nu)}(η⁵-C₉H₇)(PPh₃)₂]ⁿ⁺(n ) 0, 1).^5c-iFurthermore, we

have designed an efficient synthetic approach to termi-

nal alkynes. They can be obtained from vinylidene

(3) For representative examples see the following. [M] ) trans-

[RuClL₂]⁺(L₂) dppm (bis(diphenylphosphino)methane), dppe (1,2-

bis(diphenylphosphino)ethane)): (a) Pirio, N.; Touchard, D.; Toupet,

L.; Dixneuf, P. H. J . Chem. Soc., Chem. Commun. 1991, 980. (b)

Touchard, D.; Pirio, N.; Dixneuf, P. H. Organometallics 1995, 14, 4920.

(c) Touchard, D.; Haquette, P.; Daridor, A.; Romero, A.; Dixneuf, P.

H. Organometallics 1998, 17, 3844. (d) Rigaut, S.; Maury, O.; Touchard,

D.; Dixneuf, P. H. Chem. Commun. 2001, 373. [M] ) [RuCl{N(CH₂-

CH₂PPh₂)₃}]⁺: (e) Wolinska, A.; Touchard, D.; Dixneuf, P. H.; Romero,

A. J . Organomet. Chem. 1991, 420, 217. [M] ) [Ru(η⁵-C₅R₅)LL′]⁺(R )

H, L ) L′ ) PMe₃, PPh₃; R ) H, L ) PPh₃, L′ ) PPh₂CH₂C(dO)^tBu;

R ) H, LL′ ) dippe (1,2-bis(diisopropylphosphino)ethane); R ) Me,

L ) L′ ) PEt₃; R ) Me, LL′ ) dippe): (f) Selegue, J . P. Organometallics

1982, 1, 217. (g) de los R´ıos, I.; J ime´nez-Tenorio, M.; Puerta, M. C.;

Valerga, P. J . Organomet. Chem. 1997, 549, 221. (h) Crochet, P.;

Demerseman, B.; Vallejo, M. I.; Gamasa, M. P.; Gimeno, J .; Borge, J .;

Garc´ıa-Granda, S. Organometallics 1997, 16, 5406. (i) Bruce, M. I.;

Low, P. J .; Tiekink, E. R. T. J . Organomet. Chem. 1999, 572, 3. (j)

Bustelo, E.; J ime´nez-Tenorio, M.; Puerta, M. C.; Valerga, P. Organo-

metallics 1999, 18, 4563. [M] ) [Os(η⁵-C₅H₅)(PⁱPr₃)₂]⁺: see ref 2g.

(4) For representative examples see the following. [M] ) M(CO)₅

(M ) Cr, W): (a) Fischer, H.; Roth, G.; Reindl, D.; Troll, C. J .

Organomet. Chem. 1993, 454, 133. (b) Fischer, H.; Reindl, D.; Troll,

C.; Leroux, F. J . Organomet. Chem. 1995, 490, 221. (c) Fischer, H.;

Roth, G. J . Organomet. Chem. 1995, 490, 229. (d) Cosset, C.; del Rio,

I.; Le Bozec, H. Organometallics 1995, 14, 1938. (e) Roth, G.; Fischer,

H. J . Organomet. Chem. 1996, 507, 125. (f) Cosset, C.; del Rio, I.; Pe´ron,

V.; Windmu¨ller, B.; Le Bozec, H. Synlett 1996, 435. (g) Do¨tz, K. H.;

Paetsch, D.; Le Bozec, H. J . Organomet. Chem. 1999, 589, 11. (h)

Ulrich, K.; Porhiel, E.; Pe´ron, V.; Ferrand, V.; Le Bozec, H. J .

Organomet. Chem. 2000, 601, 78. [M] ) [Mn(η⁵-C₅H₅)(CO)₂]: (i)

Kolobova, N. E.; Ivanov, L. L.; Zhvanko, O. S.; Khitrova, O. M.;

Batsanov, A. S.; Struchkov, Y. T. J . Organomet. Chem. 1984, 265, 271.

See also ref 2b. [M] ) [RuCl(η⁶-arene)(PR₃)]⁺(PR₃) PMe₃, PPh₃): (j)

Dussel, R.; Pilette, D.; Dixneuf, P. H. Organometallics 1991, 10, 3287.

(k) Pilette, D.; Le Bozec, H.; Romero, A.; Dixneuf, P. H. J . Chem. Soc.,

Chem. Commun. 1992, 1220. (l) Pilette, D.; Ouzzine, K.; Dixneuf, P.

H.; Rickard, C. E. F.; Roper, W. R. Organometallics 1992, 11, 809. (m)

Ruiz, N.; Pe´ron, D.; Sinbandith, S.; Dixneuf, P. H.; Baldoli, C.;

Maiorana, S. J . Organomet. Chem. 1997, 533, 213. See also ref 4h.

[M] ) [Ru(η⁵-C₅H₅)(CO)(PR₃)]⁺(PR₃) PⁱPr₃, PPh₃): (n) Esteruelas,

M. A.; Go´mez, A. V.; Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.; Oro, L. A.

Organometallics 1996, 15, 3423. (o) Esteruelas, M. A.; Go´mez, A. V.;

Lo´pez, A. M.; On˜ate, E.; Ruiz, N. Organometallics 1998, 17, 2297. (p)

Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.; On˜ate, E. Organome-

tallics 1998, 17, 3567. (q) Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A.

M.; Puerta, M. C.; Valerga, P. Organometallics 1998, 17, 4959. (r)

Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.; Modrego, J .; On˜ate, E.

Organometallics 1998, 17, 5434. (s) Esteruelas, M. A.; Go´mez, A. V.;

Lo´pez, A. M.; On˜ate, E.; Ruiz, N. Organometallics 1999, 18, 1606. (t)

Bernad, D. J .; Esteruelas, M. A.; Lo´pez, A. M.; Modrego, J .; Puerta,

M. C.; Valerga, P. Organometallics 1999, 18, 4995. (u) Esteruelas, M.

A.; Go´mez, A. V.; Lo´pez, A. M.; Oliva´n, M.; On˜ate, E.; Ruiz, N.

Organometallics 2000, 19, 4. (v) Bernad, D. J .; Esteruelas, M. A.; Lo´pez,

A. M.; Oliva´n, M.; On˜ate, E.; Puerta, M. C.; Valerga, P. Organometallics

2000, 19, 4327. See also ref 2d and 4h. [M] ) fac,cis-[RuCl₂{EtN(CH₂-

CH₂PPh₂)₂}]: (w) Bianchini, C.; Peruzzini, M.; Zanobini, F.; Lopez, C.;

de los Rios, I.; Romerosa, A. Chem. Commun. 1999, 443. [M] ) [Re-

complexes, resulting from the protonation of the func-

tionalized σ-alkynyl complexes, followed by a demeta-

lation process via treatment with acetonitrile.^5gThis

procedure allows the recovery of the metallic auxiliary

as the insoluble complex [Ru(NtCMe)(η⁵-C₉H₇)(PPh₃)₂]⁺,

which can be separated quantitatively from the free

alkynes. Chart 1 collects a number of alkynyl complexes

(A-C) which can be used as efficient precursors of

terminal alkynes (D-F ).^5g,i,6Although these examples

prove the potential synthetic utility of allenylidene

complexes in organic synthesis,⁷the scope of its ap-

plication is still not comparable to that of the related

vinylidenes [M]dCdCR₂or the classical Fischer type

metal carbenes [M]dC(X)R (X ) OR′, NR′₂).^8-10

Pursuing these studies aimed at exploiting the utility

of this synthetic route, we describe in this paper the

(5) (a) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Cueva,

M.; Lastra, E.; Borge, J .; Garc´ıa-Granda, S.; Pe´rez-Carren˜o, E. Orga-

nometallics 1996, 15, 2137. (b) Gamasa, M. P.; Gimeno, J .; Gonza´lez-

Bernardo, C.; Borge, J .; Garc´ıa-Granda, S. Organometallics 1997, 16,

2483. (c) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Borge, J .; Garc´ıa-

Granda, S. Organometallics 1997, 16, 3178. (d) Cadierno, V.; Gamasa,

M. P.; Gimeno, J .; Lo´pez-Gonza´lez, M. C.; Borge, J .; Garc´ıa-Granda,

S. Organometallics 1997, 16, 4453. (e) Cadierno, V.; Gamasa, M. P.;

Gimeno, J .; Pe´rez-Carren˜o, E.; Ienco, A. Organometallics 1998, 17,

5216. (f) Cadierno, V.; Conejero, S.; Gamasa, M. P.; Gimeno, J .;

Asselberghs, I.; Houbrechts, S.; Clays, K.; Persoons, A.; Borge, J .;

Garc´ıa-Granda, S. Organometallics 1999, 18, 582. (g) Cadierno, V.;

Gamasa, M. P.; Gimeno, J .; Pe´rez-Carren˜o, E.; Garc´ıa-Granda, S.

Organometallics 1999, 18, 2821. (h) Cadierno, V.; Gamasa, M. P.;

Gimeno, J .; Lastra, E. J . Chem. Soc., Dalton Trans. 1999, 3235. (i)

Cadierno, V.; Conejero, S.; Gamasa, M. P.; Gimeno, J . J . Chem. Soc.,

Dalton Trans. 2000, 451.

(6) Cadierno, V.; Gamasa, M. P.; Gimeno, J . J . Organomet. Chem.

2001, 621, 39.

(7) Organic cumulenes have been prepared using rhodium(I)

allenylidene complexes as starting materials: (a) Wiedemann, R.;

Steinert, P.; Gevert, O.; Werner, H. J . Am. Chem. Soc. 1996, 118, 2495.

(b) Werner, H.; Wiedemann, R.; Mahr, N.; Steinert, P.; Wolf, J . Chem.

Eur. J . 1996, 2, 561. (c) Werner, H.; Laubender, M.; Wiedemann, R.;

Windmu¨ller, B. Angew. Chem., Int. Ed. Engl. 1996, 35, 1237.

(Triphos)(CO)₂]⁺(Triphos

) 1,1,1-tris(diphenylphosphinomethyl)-

ethane): (x) Bianchini, C.; Mantovani, N.; Marchi, A.; Marvelli, L.;

Masi, D.; Peruzzini, M.; Rossi, R.; Romerosa, A. Organometallics 1999,

18, 4501. (y) Bianchini, C.; Mantovani, N.; Marvelli, L.; Peruzzini, M.;

Rossi, R.; Romerosa, A. J . Organomet. Chem. 2001, 617-618, 23.

Additions of Enolates on Ru(II) Indenyl Allenylidenes

Organometallics, Vol. 20, No. 14, 2001 3177

Ch a r t 2

(a ) Rea ction s of Allen ylid en e Com p lexes [Ru -

{dCdCdC(R¹)P h }(η⁵-C₉H₇)(P P h ₃)₂][P F ₆] w ith En o-

la tes Der ived fr om Meth yl Keton es. As expected

from our previous studies,^5c-ithe allenylidene complexes

[Ru{dCdCdC(R¹)Ph}(η⁵-C₉H₇)(PPh₃)₂][PF₆] (R¹) Ph

(1), H (2))^5areact with lithium enolates LiCH₂COR²

i

(R²) Ph, Pr, Me, Fc, (E)-CHdCHPh) in tetrahydrofu-

ran, at -20 °C, to afford the neutral σ-alkynyl deriva-

tives [Ru{CtCC(R¹)Ph(CH₂COR²)}(η⁵-C₉H₇)(PPh₃)₂] (3a-

e, 4a -d ), resulting from the regioselective addition of

the nucleophile at the C_γatom. Complexes 3a -e and

4a -d have been isolated as air-stable orange solids in

62-83% yields (Scheme 1).

1

Analytical and spectroscopic data (IR and H, ³¹P{¹H},

and ¹³C{¹H} NMR) support the proposed formulations

(see the Experimental Section and Tables 1 and 2). In

particular, the formation of a γ-keto-substituted alkynyl

chain was identified on the basis of (i) the presence of

typical ν(CdO) and ν(CtC) absorption bands in the IR

spectra (KBr) at 1652-1721 and 2052-2092 cm^-1

,

respectively, and (ii) characteristic resonances in the

¹³C{¹H} NMR spectra of the Ru-CtC, C_γ, CH₂, and Cd

O carbon nuclei at δ 92.62-98.02 (²J _CP) 22.5-25.7 Hz,

C_R), 111.77-115.99 (C_â), 37.88-50.67 (C_γ), 50.51-57.63

(CH₂), and 195.68-211.21 (CdO).

synthesis of γ-keto-substituted alkynes G and H (Chart

2). The former alkynes have been obtained by starting

from the allenylidene complexes [Ru{dCdCdC(R¹)Ph}-

(η⁵-C₉H₇)(PPh₃)₂][PF₆] (R¹) Ph, H) through the addition

of lithium enolates LiCH₂COR². Alkynes H have been

synthesized diastereoselectively using similar additions

on the optically active allenylidene derivative [Ru{dCd

CdC(C₉H₁₆)}(η⁵-C₉H₇)(PPh₃)₂][PF₆] (C(C₉H₁₆) ) (1R)-

1,3,3-trimethylbicyclo[2.2.1]hept-2-ylidene). The prepa-

ration of unsaturated carbene complexes J , which are

obtained via protonation of cyclic alkenyl derivatives I,

is also reported. The alkenyl complexes I result from

the intramolecular cyclization of the keto-functionalized

σ-alkynyl species [Ru{CtCCR¹R²(CH₂COR³)}(η⁵-C₉H₇)-

(PPh₃)₂] in the presence of AlCl₃. Part of this work has

been communicated in a preliminary report.^5e

(b) Syn th esis of Vin ylid en e Com p lexes [Ru {dCd

C(H)C(R¹)P h (CH₂COR²)}(η⁵-C₉H₇)(P P h ₃)₂][BF₄]. The

treatment of σ-alkynyl complexes 3a -e and 4a -d with

HBF₄‚Et₂O in diethyl ether at -20 °C generates the air-

stable vinylidene complexes [Ru{dCdC(H)C(R¹)Ph-

(CH₂COR²)}(η⁵-C₉H₇)(PPh₃)₂][BF₄] (5a -e and 6a -d ;

74-94% yields) (Scheme 1). Elemental analyses and

spectroscopic data are in accordance with the proposed

formulations (see the Experimental Section and Tables

3 and 4 for details). The most remarkable feature in the

¹H NMR spectra of these complexes is the presence of

a singlet (5a -e) or doublet (6a -d ; ca. J _HH) 10 Hz)

signal in the range 4.50-5.76 ppm attributed to the

acidic vinylidene proton [Ru]dCdCH (Table 3). The

characteristic deshielded C_Rresonance appears, in the

¹³C{¹H} NMR spectra, as a triplet (²J _CP) 15.1-17.9

Hz) at δ 340.50-344.41, while the C_â, C_γ, CH₂and Cd

O carbon nuclei resonate as singlets at higher fields (δ

115.90-116.79 (C_â), 34.24-48.21 (C_γ), 48.12-53.24

(CH₂), and 196.89-213.36 (CdO); see Table 4).

(c) Dem eta la tion P r ocesses. Demetalation of com-

plexes 5a -e and 6a -d proceeds rapidly (ca. 30 min) in

refluxing acetonitrile to afford terminal γ-keto-substi-

tuted alkynes HCtCC(R¹)Ph(CH₂COR²) (7a -e and 8a -

d ) and the cationic nitrile complex [Ru(NtCMe)(η⁵-

C₉H₇)(PPh₃)₂][BF₄] (9)^5g(Scheme 1). Keto-alkynes 7a-d

and 8a -d have been purified from the reaction mixture

by column chromatography on silica gel (72-86% yield)

after filtering off the unsoluble complex 9. They have

been characterized by means of standard spectroscopic

techniques and microanalysis (see the Experimental

Section and Tables 5 and 6). The most relevant spec-

troscopic features of 7a -e and 8a -d are (i) (¹H NMR)

the singlet (7a -e) or doublet (8a -d ; ca. J _HH) 2 Hz)

resonance for the acetylenic proton (δ 2.25-2.73) and

(ii) (¹³C{¹H} NMR) typical signals for the HCtC carbons

which appear in the ranges δ 70.71-75.10 and 84.87-

87.84, respectively.¹¹

Resu lts a n d Discu ssion

Syn th esis of Ter m in a l Alk yn es HCtCC(R¹)P h -

(CH₂COR²). The synthetic route is based on the same

procedure that we have previously described.^5g,iThus,

with allenylidene complexes as the starting materials,

the first step involves the preparation of the corre-

sponding σ-alkynyl derivatives, which are transformed

into vinylidene species. The treatment of these vi-

nylidenes with acetonitrile finally gives the free alkynes

through a demetalation process.

(8) For recent reviews on the chemistry of vinylidene complexes

see: (a) Werner, H. J . Organomet. Chem. 1994, 475, 44. (b) Bruneau,

C.; Dixneuf, P. H. Acc. Chem. Res. 1999, 32, 311. (c) Puerta, M. C.;

Valerga, P. Coord. Chem. Rev. 1999, 193-195, 977. See also ref 1a.

(9) Extensive surveys and reviews have been published on the

chemistry of Fischer type carbene complexes. For recent references

see: (a) Sierra, M. A. Chem. Rev. 2000, 100, 3591. (b) Zaragoza

Do¨rwald, F. In Metal Carbenes in Organic Synthesis; Wiley-VCH:

Weinheim, Germany, 1999. (c) Do¨tz, K. H.; Tomuschat, P. Chem. Soc.

Rev. 1999, 28, 187. (d) Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998,

98, 911.

(10) A few examples of catalytic transformations of propargylic

alcohols via ruthenium(II) allenylidene intermediates have been

reported: (a) Trost, B. M.; Flygare, J . A. J . Am. Chem. Soc. 1992, 114,

5476. (b) Trost, B. M.; Flygare, J . A. Tetrahedron Lett. 1994, 35, 4059.

(c) Nishibayashi, Y.; Wakiji, I.; Hidai, M. J . Am. Chem. Soc. 2000, 122,

11019. (d) The catalytic activity of ruthenium(II) allenylidene com-

plexes in ring-closing metathesis (RCM) of olefins has been recently

discovered: Fu¨rstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012 and

references therein.

3178 Organometallics, Vol. 20, No. 14, 2001

Cadierno et al.

Sch em e 1

Ta ble 1. ³¹P {¹H} a n d ¹H NMR Da ta for Neu tr a l σ-Alk yn yl Com p lexes

[Ru {CtCC(R¹)P h (CH₂COR²)}(η⁵-C₉H₇)(P P h ₃)₂]^a

¹H

η⁵-C₉H₇

n

complex

³¹P{¹H} H-1,3

H-2

J _HH

H-4,5,6,7

CH₂

others

R¹) R²) Ph (3a )

53.14 s 4.75 d 5.64 t

2.3 6.53 m, 6.78 m 3.99 s

6.84-7.76 (m, Ph)

R¹) Ph, R²) ⁱPr (3b) 52.19 s 4.78 d 5.71 t

2.0 6.46 m, b

2.5 6.42 m, b

3.52 s

3.48 s

0.91 (d, J _HH) 6.8, CH₃); 2.29 (sept, J _HH) 6.8, CH);

6.81-7.63 (m, Ph)

R¹) Ph, R²) Me (3c) 52.24 s 4.73 d 5.63 t

R¹) Ph, R²) Fc (3d ) 53.42 s 4.70 d 5.63 t

1.85 (s, CH₃); 6.81-7.57 (m, Ph)

3.81 (s, C₅H₅); 4.03 and 4.61 (br, C₅H₄); 6.87-7.89

(m, Ph)

6.52 and 7.72 (d, J _HH) 15.9, dCH); 6.89-7.60

(m, Ph)

2.3 6.56 m, 6.78 m 3.89 s

R¹) Ph, R²

)

52.00 s 4.80 d 5.83 t

2.0 6.35 m, 6.78 m 3.72 s

(E)-CHdCHPh (3e)

R¹) H, R²) Ph (4a ) 52.47 br 4.54 br 5.40 br

4.71 br

6.27 m, 6.67 m 3.17 dd^c5.04 (dd, J _HH) 9.0, J _HH) 5.3, CH);

3.64 dd^d

6.30 m, 6.71 m 2.76 dd^f0.91 (d, J _HH) 7.0, CH₃); 0.99 (d, J _HH

3.04 dd^g

6.9, CH₃); 2.36 (m, CH(CH₃)₂); 4.85 (dd,

J _HH) 8.0, J _HH) 6.4, CH); 6.85-7.53 (m, Ph)

6.35 m, 6.75 m 2.62 ddⁱ1.88 (s, CH₃); 5.20 (dd, J _HH) 9.2, J _HH) 5.3, CH);

2.94 dd^j

6.88-7.53 (m, Ph)

6.28 m, 6.69 m 3.26 dd^l3.89 (s, C₅H₅); 4.11 and 4.60 (br, C₅H₄);

6.84-8.03 (m, Ph)

R¹) H, R²) ⁱPr (4b) 49.38 d^e4.64 br 5.56 br

49.87 d^e4.73 br

)

R¹) H, R²) Me (4c) 51.88 d^h4.67 br 5.53 br

52.35 d^h4.73 br

R¹) H, R²) Fc (4d )

51.94 d^k4.77 br 5.59 br

52.52 d^k4.82 br

3.37 dd^m

5.13 (dd, J _HH) 7.7, J _HH) 6.9, CH);

6.88-7.67 (m, Ph)

a

Spectra recorded in C₆D₆; δ in ppm and J in Hz. Abbreviations: s, singlet; br, broad; d, doublet; dd, doublet of doublets; t, triplet;

sept, septuplet; m, multiplet. Overlapped by Ph protons. J _HH) 15.5, J _HH) 5.3. J _HH) 15.5, J _HH) 9.0. ²J _PP) 30.3. J _HH) 15.5,

b

c

d

e

f

J _HH) 6.4. J _HH) 15.5, J _HH) 8.0. ²J _PP) 31.7. J _HH) 14.8, J _HH) 5.3. J _HH) 14.8, J _HH) 9.2. ²J _PP) 29.9. J _HH) 15.6, J _HH) 7.7.

g

h

i

j

k

l

m

n

J _HH) 15.6, J _HH) 6.9. Legend for indenyl skeleton:

Diaster eoselective Syn th esis of Ter m in al Alkyn es

C₉H₇)(P P h ₃)₂][P F ₆]. Following the well-known Selegue

synthetic protocol,^3fthe chiral allenylidene derivative

[Ru{dCdCdC(C₉H₁₆)}(η⁵-C₉H₇)(PPh₃)₂][PF₆] (12) was

prepared (80% yield) by refluxing [RuCl(η⁵-C₉H₇)-

(PPh₃)₂] (10),¹²NaPF₆, and 2-exo-ethynyl-1,3,3-tri-

methyl-2-endo-norbornanol (11)¹³in methanol (Scheme

2). Spectroscopic data (see the Experimental Section)

for 12 are similar to those reported for the related

allenylidene complexes [Ru(dCdCdCRR′)(η⁵-C₉H₇)-

(PPh₃)₂][PF₆].^5a,hSignificantly, the presence of the cu-

mulenic moiety was clearly identified on the basis of a

strong ν(CdCdC) IR absorption at 1963 cm^-1and the

H CtCC(C₉H ₁₆)(CH ₂COR ). The efficient access to

alkynes 7a -e and 8a -d from allenylidene complexes

1 and 2 and methyl ketones prompted us to use chiral

substrates in order to obtain optically active terminal

alkynes. Toward this aim, a novel allenylidene complex

bearing a chiral auxiliary derived from the commercially

available ketone (-)-fenchone was prepared. The sub-

sequent transformations leading to the formation of the

desired terminal alkynes are similar to those previously

mentioned.

(a) Syn th esis of th e Optically Active Allen yliden e

Ru th en iu m (II) Com p lex [Ru {dCdCdC(C₉H₁₆)}(η⁵-

(12) Oro, L. A.; Ciriano, M. A.; Campo, M.; Foces-Foces, C.; Cano,

F. H. J . Organomet. Chem. 1985, 289, 117.

(13) Keegan, D. S.; Midland, M. M.; Werley, R. T.; McLoughlin, J .

I. J . Org. Chem. 1991, 56, 1185.

(11) To the best of our knowledge only the terminal alkyne 8a has

been previously reported: Caffyn, A. J . M.; Nicholas, K. M. J . Am.

Chem. Soc. 1993, 115, 6438.

Additions of Enolates on Ru(II) Indenyl Allenylidenes

Organometallics, Vol. 20, No. 14, 2001 3179

Ta ble 2. ¹³C{¹H} NMR Da ta for Neu tr a l σ-Alk yn yl Com p lexes

[Ru {CtCC(R¹)P h (CH₂COR²)}(η⁵-C₉H₇)(P P h ₃)₂]^a

η⁵-C₉H₇

2

complex C-1,3

C-2 C-3a,7a ∆δ(C-3a,7a)^bC-4,5,6,7 Ru-C_RJ _CP

C_â

C_γ

CH₂

CdO

others

3a

3b

3c

3d

74.72 96.81 110.69

-20.01

-20.12

-20.43

-19.99

124.56 95.42 t 22.7 115.24 50.40 51.94 196.30 126.07-150.05 (m, Ph)

c

74.28 96.65 110.58

74.11 96.38 110.27

75.23 96.48 110.71

124.35 96.94 t 22.5 114.76 50.37 54.43 211.19 18.81 (s, CH₃); 41.31 (s, CH);

126.01

124.07 97.40 t 22.6 113.92 49.72 57.63 206.18 31.41 (s, CH₃); 127.41-

125.82 149.26 (m, Ph)

124.51 95.94 t 23.3 115.99 50.67 53.15 199.62 70.22 and 72.24 (s, CH of

127.76-149.78 (m, Ph)

c

C₅H₄); 70.50 (s, C₅H₅);

82.31 (s, C of C₅H₄);

126.39-150.14 (m, Ph)

3e

4a

74.35 96.74 110.18

75.16^e96.38 109.08

-20.52

-20.80

124.00 98.02 t 23.0 113.90 50.21 56.97 197.39 126.10-149.36 (m, Ph and

d

dCH)

123.46 94.24 vt 24.3 112.16 38.92 50.51 198.86 126.76-146.84 (m, Ph)

124.46

75.38^f

110.72

125.90

126.68

4b

4c

4d

74.47^g95.74 108.84

74.57^h

109.89

-21.33

-20.66

-21.44

123.02 92.73 vt 24.7 111.77 37.88 51.76 211.21 18.13 and 18.19 (s, CH₃);

123.58

125.47

c

41.32 (s, CH); 126.00-

146.29 (m, Ph)

75.18ⁱ94.64 109.65

110.43

123.87 94.64 vt 24.1 111.99 38.81 55.03 206.58 31.04 (s, CH₃); 127.93-

124.29

126.25

126.59

146.66 (m, Ph)

74.65 95.79 108.44

122.81 92.62 vt 25.7 112.03 38.13 51.21 195.68 69.46, 70.30, 71.89 and 72.11

74.90

110.07

123.74

125.26

126.09

(s, CH of C₅H₄); 69.90

(s, C₅H₅); 80.81 (s, C of

C₅H₄); 127.25-146.58

(m, Ph)

a

Spectra recorded in C₆D₆; δ in ppm and J in Hz. Abbreviations: s, singlet; d, doublet; t, triplet; vt, virtual triplet; m, multiplet.

∆δ(C-3a,7a) ) δ(C-3a,7a(η-indenyl complex)) - δ(C-3a,7a(sodium indenyl)), δ(C-3a,7a) for sodium indenyl 130.70 ppm. ^cOverlapped by

b

Ph carbons. 125.66 and 125.83 (s, dCH and C-4,7 or C-5,6). ^ed, ²J _CP) 3.5. ^fd, ²J _CP) 3.5. d, ²J _CP) 7.2. d, ²J _CP) 6.9. Broad signal.

d

g

h

i

Ta ble 3. ³¹P {¹H} a n d ¹H NMR Da ta for Ca tion ic Vin ylid en e Com p lexes

[Ru {dCdC(H)C(R¹)P h (CH₂COR²)}(η⁵-C₉H₇)(P P h ₃)₂][BF ₄]^a

¹H

η⁵-C₉H₇

complex

³¹P{¹H}

H-1,3

H-2

J _HH

H-4,5,6,7

RudCdCH

CH₂

others

R¹) R²) Ph (5a )

36.51 s

5.03 d

5.07 d

6.08 t

6.09 t

2.1 5.14 m, 7.04 m

2.1 5.16 m, 7.03 m

5.73 s

5.76 s

3.16 s

2.65 s

6.53-7.71 (m, Ph)

R¹) Ph, R²) ⁱPr (5b) 36.56 s

0.74 (d, J _HH) 6.8, CH₃); 2.20

(sept, J _HH) 6.8, CH); 6.56-

7.53 (m, Ph)

R¹) Ph, R²) Me (5c) 36.55 s

R¹) Ph, R²) Fc (5d ) 36.28 s

5.05 d

5.98 t

6.04 t

1.8 5.14 m, 7.05 m

1.2 5.16 m, 7.03 m

5.45 s

5.33 s

2.48 s

2.53 s

1.67 (s, CH₃); 6.51-7.52 (m, Ph)

3.72 (s, C₅H₅); 4.52 and 4.54

(br, C₅H₄); 6.44.7.51 (m, Ph)

6.33 (d, J _HH) 16.0, dCH); 6.54-

7.53 (m, Ph and dCH)

R¹) Ph, R²

)

36.40 s

5.06 d

6.07 t

1.9 5.16 m, 7.04 m

5.58 s

2.84 s

(E)-CHdCHPh (5e)

R¹) H, R²) Ph (6a )

37.96 d^b5.13 br 6.25 br

40.16 d^b

37.98 d^h5.21 br 6.34 br

40.29 d^h

c, d

i, d

4.77 d^e

4.75 d^j

3.24 dd^f4.37 (m, CH); 6.52-8.14 (m, Ph)

c

3.50 dd^g

R¹) H, R²) ⁱPr (6b)

k

1.09 (d, J _HH) 6.9, CH₃); 1.19 (d,

J _HH) 6.8, CH₃); 4.21 (m, CH);

6.51-7.42 (m, Ph)

i

3.01 dd^l

R¹) H, R²) Me (6c)

R¹) H, R²) Fc (6d )

38.08 d^h5.27 br 6.20 br

40.52 d^h5.62 br

5.75 m, d

4.52 d^e

2.80 m

2.99 m

2.20 (s, CH₃); 6.56-7.45 (m, Ph)

38.36 d^m5.14 br 6.23 br

39.89 d^m5.59 br

5.70 m, 6.85 m

n

4.25 (s, C₅H₅); 6.76-7.74 (m, Ph)

a

Spectra recorded in CDCl₃; δ in ppm and J in Hz. Abbreviations: s, singlet; br, broad; d, doublet; dd, doublet of doublets; t, triplet;

sept, septuplet; m, multiplet. ²J _PP) 23.5. ^c5.64 (m, 3H, H-1 or H-3 and H-4, H-5, H-6 or H-7). Overlapped by Ph protons. J _HH

)

b

d

e

10.2. J _HH) 17.4, J _HH) 4.5. J _HH) 17.4, J _HH) 9.6. ²J _PP) 23.4. 5.67 (m, 3H, H-1 or H-3 and H-4, H-5, H-6 or H-7). J _HH) 9.4.

f

g

h

i

j

k

l

m

n

2.72 (m, 2H, CH(CH₃)₂and CH₂). J _HH) 17.4, J _HH) 8.9.

²J _PP) 32.1. 4.50 (m, 6H, RudCdCH, CH and C₅H₄).

low-field resonances, in the ¹³C{¹H} NMR spectrum, for

yl derivatives [Ru{CtCC(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)-

2

the RudCdCdC carbon nuclei: δ 305.06 (vt, J _CP

²J _CP′) 18.9 Hz, RudC_R), 202.01 (C_â), and 183.24 (C_γ).

(b ) R ea ct ion s of [R u {dCdCdC(C₉H ₁₆)}(η⁵-C₉-

H₇)(P P h ₃)₂][P F₆] with En olates Der ived fr om Meth -

yl Keton es. The allenylidene complex 12 reacts with

lithium enolates derived from acetophenone, methyl

isopropyl ketone, and acetone, affording the σ-alkyn-

)

(PPh₃)₂] (13a -c) in 68-77% yield after chromatographic

workup (Scheme 3). Formation of compounds 13a -c

involves, as expected, the regioselective addition of the

nucleophile at the C_γatom of the allenylidene chain

leading to the generation of a novel stereogenic center

at C_γ. Enolate additions proceed in a diastereoselective

manner, since only one diastereoisomer was detected

3180 Organometallics, Vol. 20, No. 14, 2001

Cadierno et al.

Ta ble 4. ¹³C{¹H} NMR Da ta for Ca tion ic Vin ylid en e Com p lexes

[Ru {dCdC(H)C(R¹)P h (CH₂COR²)}(η⁵-C₉H₇)(P P h ₃)₂][BF ₄]^a

η⁵-C₉H₇

C-2 C-3a,7a ∆δ(C-3a,7a)^bC-4,5,6,7 RudC_R²J _CP

complex C-1,3

C_â

C_γ

CH₂CdO

others

5a

5b

5c

5d

80.45 98.09 117.60

-13.10

-13.22

-13.19

-13.23

123.86 344.41 t 17.9 116.79 47.82 48.12 197.33 127.36-147.66 (m, Ph)

c

80.23 98.30 117.48

80.33 97.94 117.51

80.27 97.73 117.47

123.70 343.76 t 17.9 116.65 48.21 50.34 212.82 18.00 (s, CH₃); 42.19 (s, CH);

127.23

123.72 343.69 t 17.6 116.58 48.01 52.02 206.23 32.36 (s, CH₃); 127.65-

126.27 147.31 (m, Ph)

123.70 342.24 t 17.9 115.90 47.91 48.42 200.53 66.08 and 70.05 (s, CH of

127.94-147.29 (m, Ph)

127.31

C₅H₄); 69.89 (s, C₅H₅);

79.93 (s, C of C₅H₄);

127.46-147.89 (m, Ph)

5e

6a

79.77 97.66 116.92

82.69^d99.82 114.78

-13.78

-13.69

123.16 343.39 t 17.7 116.27 47.80 50.47 196.89 126.38 and 141.86 (s, dCH);

126.67

122.65 343.24 vt 16.2 116.69 35.31 48.86 199.21 127.62-144.09 (m, Ph)

124.71

126.92-146.81 (m, Ph)

82.87^e

119.23

c

6b

6c

6d

81.88^f99.46 113.87

82.32^g

118.53

-14.50

-13.93

-13.63

121.93 342.89 vt 16.6 116.31 34.24 50.01 213.36 17.77 and 18.02 (s, CH₃);

124.16

126.81

c

41.37 (s, CH); 127.16-

143.55 (m, Ph)

82.66 99.39 114.53

83.12 119.01

122.49 340.50 vt 15.2 116.67 34.26 53.24 206.89 31.12 (s, CH₃); 127.30-

124.55

c

143.89 (m, Ph)

82.61 99.35 114.82

82.72 119.32

122.44 342.41 vt 15.1 116.43 35.19 50.10 202.38 69.53, 70.00, 73.43 and

124.62

127.29

127.38

73.62 (s, CH of C₅H₄);

70.27 (s, C₅H₅); 79.63

(s, C of C₅H₄); 128.64-

143.80 (m, Ph)

a

Spectra recorded in CDCl₃; δ in ppm and J in Hz. Abbreviations: s, singlet; d, doublet; t, triplet; vt, virtual triplet; m, multiplet.

∆δ(C-3a,7a) ) δ(C-3a,7a(η-indenyl complex)) - δ(C-3a,7a(sodium indenyl)), δ(C-3a,7a) for sodium indenyl 130.70 ppm. ^cOverlapped by

b

Ph carbons. d, J _CP) 10.1. ^ed, J _CP) 7.9. ^fd, J _CP) 7.7. d, J _CP) 7.3.

d

2

g

2

Ta ble 5. IR^aa n d ¹H NMR^bDa ta for Ter m in a l Alk yn es HCtCC(R¹)P h (CH₂COR²)

IR

¹H

compd

ν (HCt) ν (CtC) ν (CdO) HCt

CH₂

others

R¹) R²) Ph (7a )

3280

3244

2104

2111

1698

1709

2.63 s 4.07 s

2.66 s 3.52 s

7.21-7.94 (m, Ph)

R¹) Ph, R²) ⁱPr (7b)

1.02 (d, J _HH) 6.9, CH₃); 2.57 (sept, J _HH) 6.9, CH); 7.20-7.45

(m, Ph)

R¹) Ph, R²) Me (7c)

R¹) Ph, R²) Fc (7d )

3283

3248

3247

2118

2109

1699

1667

1677

2.69 s 3.45 s

2.66 s 3.83 s

2.73 s 3.68 s

2.05 (s, CH₃); 7.22-7.44 (m, Ph)

4.18 (s, C₅H₅); 4.47 and 4.76 (br, C₅H₄); 7.12-7.64 (m, Ph)

6.65 (d, J _HH) 16.0, dCH); 7.21-7.52 (m, Ph and dCH)

R¹) Ph, R²

)

(E)-CHdCHPh (7e)

R¹) H, R²) Ph (8a )

3286

3250

2113

1683

1701

2.28 d^c3.37 dd^d4.47 (ddd, J _HH) 8.0, J _HH) 6.0, J _HH) 2.3, CH); 7.24-7.97

3.62 dd^e

(m, Ph)

2.25 d^f2.83 dd^g1.02 (d, J _HH) 7.1, CH₃); 1.10 (d, J _HH) 6.9, CH₃); 2.53 (m,

R¹) H, R²) ⁱPr (8b)

2.94 dd^h

CH(CH₃)₂); 4.27 (ddd, J _HH) 8.7, J _HH) 6.4, J _HH) 2.5, CH);

7.25-7.43 (m, Ph)

R¹) H, R²) Me (8c)

R¹) H, R²) Fc (8d )

3279

3301

2118

2110

1696

1664

2.26 dⁱ2.82 dd^j2.15 (s, CH₃); 4.21 (ddd, J _HH) 8.2, J _HH) 6.0, J _HH) 2.2,

3.01 dd^k

2.29 d^l3.13 dd^m4.07 (s, C₅H₅); 4.46 (ddd, J _HH) 7.0, J _HH) 6.7, J _HH) 2.6, CH);

3.29 ddⁿ

4.50 and 4.75 (br, C₅H₄); 7.26-7.52 (m, Ph)

CH); 7.25-7.40 (m, Ph)

a

b

KBr; ν in cm^-1

.

Spectra recorded in CDCl₃; δ in ppm and J in Hz. Abbreviations: s, singlet; br, broad; d, doublet; dd, doublet of

c d e

doublets; ddd, doublet of doublet of doublets; sept, septuplet; m, multiplet. J _HH) 2.3. J _HH) 17.1, J _HH) 6.0. J _HH) 17.1, J _HH) 8.0.

^fJ _HH) 2.5. J _HH) 16.7, J _HH) 6.4. J _HH) 16.7, J _HH) 8.7. J _HH) 2.2. J _HH) 16.8, J _HH) 6.0. J _HH) 16.8, J _HH) 8.2. J _HH) 2.6.

g

h

i

j

k

l

m

n

J _HH) 17.4, J _HH) 6.7. J _HH) 17.4, J _HH) 7.0.

by NMR spectroscopy (see Tables 7 and 8).¹⁴Since the

configuration of the new chiral atom could not be

elucidated from the NMR data, a single-crystal X-ray

structural determination was carried out on complex

13b. An ORTEP view of the molecular geometry of this

complex is shown in Figure 1. Selected bond distances

and angles which are collected in the caption can be

compared with those previously reported by us for other

ruthenium(II) indenyl σ-alkynyl complexes [Ru(CtCR)-

(η⁵-C₉H₇)(PPh₃)₂]^5d-f(caution must be used in the

comparison of these data, due to the relative imprecision

of the crystallographic determination). As expected, the

structure of 13b clearly indicates that the addition of

the [ⁱPrCOCH₂]^-moiety takes place on the less steri-

cally congested exo face of the allenylidene chain in [Ru-

{dCdCdC(C₉H₁₆)}(η⁵-C₉H₇)(PPh₃)₂][PF₆] (12). On the

basis of steric requirements, an analogous conformation

is also proposed for σ-alkynyl derivatives 13a and 13c.

(c) Syn t h esis of Vin ylid en e Com p lexes [R u -

{dCdC(H )C(C₉H ₁₆)(CH ₂COR )}(η⁵-C₉H ₇)(P P h ₃)₂]-

(14) The formation of only one diastereoisomer was confirmed in

the crude reaction mixture by ¹H and ³¹P{¹H} NMR spectroscopy.

Additions of Enolates on Ru(II) Indenyl Allenylidenes

Organometallics, Vol. 20, No. 14, 2001 3181

Ta ble 6. ¹³C{¹H} NMR Da ta for Ter m in a l Alk yn es HCtCC(R¹)P h (CH₂COR²)^a

compd

tCH

tC

C_γ

CH₂

CdO

others

7a

74.24

87.77

47.04

49.50

195.51

127.14, 127.42, 128.41, 128.68, 128.80, and 133.33 (s, CH of Ph); 137.64 and

144.41 (s, C of Ph)

7b

74.38

87.63

46.79

51.52

210.42

18.31 (s, CH₃); 41.62 (s, CH); 127.16, 127.34, and 128.65 (s, CH of Ph); 144.36

(s, C of Ph)

7c

7d

74.63

73.91

86.99

87.84

46.42

46.32

54.70

49.92

205.09

198.73

31.18 (s, CH₃); 126.96, 127.10, and 128.42 (s, CH of Ph); 143.66 (s, C of Ph)

69.17 and 72.07 (s, CH of C₅H₄); 69.69 (s, C₅H₅); 79.16 (s, C of C₅H₄); 126.68,

127.07 and 128.22 (s, CH of Ph); 144.26 (s, C of Ph)

126.29 and 142.52 (s, dCH); 127.26, 127.46, 128.59, 128.68, 129.12, and 130.65

(s, CH of Ph); 134.82 (s, C of Ph)

127.10, 127.40, 128.06, 128.55, 128.66, and 133.23 (s, CH of Ph); 136.55 and

140.52 (s, C of Ph)

17.59 and 17.65 (s, CH₃); 41.17 (s, CH); 127.29, 128.58, and 133.51 (s, CH of Ph);

140.45 (s, C of Ph)

7e

8a

8b

75.10

70.95

70.72

87.38

85.23

85.19

47.21

32.57

32.45

53.04

47.01

48.63

196.16

196.67

211.09

8c

8d

70.98

70.71

84.87

85.93

32.46

32.09

51.55

48.23

205.45

200.29

30.49 (s, CH₃); 127.12, 127.25, and 128.65 (s, CH of Ph); 140.17 (s, C of Ph)

69.03, 69.24, and 72.35 (s, CH of C₅H₄); 69.61 (s, C₅H₅); 78.42 (s, C of C₅H₄);

127.18, 127.64, and 128.64 (s, CH of Ph); 140.83 (s, C of Ph)

a

Spectra recorded in CDCl₃; δ in ppm.

Ta ble 7. ³¹P {¹H} a n d ¹H NMR Da ta for Neu tr a l σ-Alk yn yl Com p lexes

[Ru {CtCC(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(P P h ₃)₂]^a

¹H

h

η⁵-C₉H₇

complex

³¹P{¹H} ²J _PP

52.89 d 34.6 4.53 br 5.75 br 6.03 d,^bc

54.44 d 5.07 br

H-1,3

H-2

H-4,5,6,7 CH₂CdO

others

R ) Ph (13a )

3.32 br

0.98, 1.52, and 2.08 (m, CH₂); 1.17, 1.23, and 1.92 (s, CH₃);

3.06 (m, CH); 6.62-7.98 (m, Ph)

0.80 and 1.00 (d, J _HH) 6.8, CH(CH₃)₂); 0.86, 1.32, and

1.72 (s, CH₃); 0.93 and 1.58 (m, CH₂); 1.75-2.13 (m,

CH₂and CH(CH₃)₂); 3.14 (m, CH); 6.70-7.67 (m, Ph)

1.20, 1.23, 1.60, and 1.78 (s, CH₃); 1.22, 1.70, and 2.15

(m, CH₂); 3.08 (m, CH); 6.67-7.05 (m, Ph)

R ) ⁱPr (13b) 53.23 d 36.6 4.34 br 5.64 br 6.00 d,^bc

54.29 d 5.20 br

2.66 d^e

2.79 d^e

R ) Me (13c) 53.00 d 34.6 4.44 br 5.65 br 6.00 d,^fc

53.98 d 5.10 br

2.53 d^g

2.67 d^g

a

Spectra recorded in C₆D₆; δ in ppm and J in Hz. Abbreviations: s, singlet; br, broad; d, doublet; sept, septuplet; m, multiplet.

J _HH) 8.5. ^cOverlapped by Ph protons. J _HH) 8.2. J _HH) 18.6. J _HH) 8.7. J _HH) 18.3. Legend for indenyl skeleton:

b

d

e

f

g

h

Sch em e 2

coupling with the two diastereotopic phosphorus nuclei

(²J _CP) 14.1-19.5 Hz). Remarkably, demetalation of

14a -c with acetonitrile takes place even at room

temperature (ca. 30 min), giving the optically active

terminal alkynes 15a -c, which have been isolated in

70-97% yield. Confirmation of the identity of 15a -c

was achieved by IR and NMR spectroscopy, elemental

analyses, and/or high-resolution mass spectrometry (see

the Experimental Section and Tables 11 and 12).

Assuming that the stereogenic C_γatom in σ-alkynyl

complexes 13a -c is not involved in the protonation and

demetalation processes, an exo disposition of the ketonic

fragment is also proposed for vinylidenes 14a -c and

terminal alkynes 15a -c.

Syn th esis of Un sa tu r a ted Ru th en iu m (II) Cyclic

Alk en yl a n d Ca r ben e Com p lexes. Among the syn-

thetic routes to oxacycloalkylidene complexes, those

based on intramolecular nucleophilic additions of hy-

droxy groups at the C_Rof vinylidene moieties are one

of the most efficient.¹⁵It could be anticipated that the

enol resonance form of the keto-substituted vinylidene

complexes 5a -e, 6a -d , and 14a -c would fulfill these

expectations, driving the reaction to the formation of

the desired intramolecular addition products. However,

these vinylidene complexes are stable in solution and

[BF ₄] a n d Dem eta la tion Rea ction s. Transformation

of complexes 13a -c into the corresponding terminal

alkynes HCtCC(C₉H₁₆)(CH₂COR) (15a -c) using our

synthetic methodology proceeds efficiently (see Scheme

3). Thus, in a first step the air-sensitive vinylidene

derivatives [Ru{dCdC(H)C(C₉H₁₆)(CH₂COR)}(η⁵-C₉-

H₇)(PPh₃)₂][BF₄] (14a -c) were prepared by protonation

of 13a -c with HBF₄‚Et₂O in diethyl ether at -20 °C

(83-96% yield). Spectroscopic data of 14a -c are in

agreement with the proposed structures, being compa-

rable to those observed for the related vinylidenes 5a -e

and 6a -d (see Tables 9 and 10). We note, in particular,

the presence of the expected low-field carbenic C_R

resonance in ¹³C{¹H} NMR spectra at ca. 328 ppm,

which appears as a doublet of doublets due to the

(15) For a review see: Weyershausen, B.; Do¨tz, K. H. Eur. J . Inorg.

Chem. 1999, 1057.

3182 Organometallics, Vol. 20, No. 14, 2001

Cadierno et al.

Sch em e 3

Ta ble 8. ¹³C{¹H} NMR Da ta for Neu tr a l σ-Alk yn yl Com p lexes [Ru {CtCC(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(P P h ₃)₂]^a

η⁵-C₉H₇

2

complex

C-1,3

75.26 dd^c97.18 110.61

C-2 C-3a,7a ∆δ(C-3a,7a)^bC-4,5,6,7 Ru-C_RJ _CP

C_â

C_γCH₂CdO CdO

others

13a

-19.61

123.86 85.29 vt 22.9 114.88 54.99

48.56

199.34 20.27, 28.37, and 28.48

(s, CH₃); 26.81, 35.67,

and 42.34 (s, CH₂);

45.74 and 52.65

75.50 d^d

74.24

111.56

125.21

125.88

126.88

(s, C); 53.09 (s, CH);

127.74-140.78 (m, Ph)

212.30 18.59, 19.69, 22.95, 27.67,

and 29.56 (s, CH₃);

26.14, 35.10, and

13b

96.77 108.96

112.30

-20.07

122.52 84.36 vt 22.0 114.78 54.30

49.92

124.66

125.61

127.13

41.60, (s, CH₂); 41.03

(s, 44.92 and 52.06

(s, C); CH(CH₃)₂);

44.92 and 52.06 (s, C);

51.94 (s, CH); 127.26-

140.16 (m, Ph)

13c

74.06 vt^e96.56 109.38

74.45 vt^f

111.77

-20.12

122.83 85.02 vt 22.4 114.62 54.20

51.88

206.74 19.67, 27.56, 27.78,

and 30.76 (s, CH₃);

26.22, 35.04, and

124.92

125.28

126.16

41.56 (s, CH₂); 44.91

and 52.47 (s, C);

51.88 (s, CH); 127.16-

140.09 (m, Ph)

a

Spectra recorded in C₆D₆; δ in ppm and J in Hz. Abbreviations: s, singlet; d, doublet; dd, doublet of doublets; vt, virtual triplet;

b

m, multiplet. ∆δ(C-3a,7a) ) δ(C-3a,7a(η-indenyl complex)) - δ(C-3a,7a(sodium indenyl)), δ(C-3a,7a) for sodium indenyl 130.70 ppm.

²J _CP) 5.4, J _CP′) 3.3. ²J _CP) 6.5. ²J _CP

) )

²J _CP′) 2.5. ²J _CP²J _CP′) 5.4.

c

2

d

e

f

Ta ble 9. ³¹P {¹H} a n d ¹H NMR Da ta for Ca tion ic Vin ylid en e Com p lexes

[Ru {dCdC(H)C(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(P P h ₃)₂][BF ₄]^a

¹H

η⁵-C₉H₇

2

complex

³¹P{¹H} J _PPH-1,3

H-2

H-4,5,6,7

RudCdCH CH₂CdO

others

R ) Ph (14a ) 35.23 d 22.8 5.59 br 6.12 br 5.26 m, b

5.12 s

2.26 d^c

3.13 d^c

0.39, 0.75, and 1.39 (s, CH₃); 1.20, 1.64,

and 1.87 (m, CH₂); 2.05 (m, CH);

6.44-7.87 (m, Ph)

0.36, 0.77, and 1.30 (s, CH₃); 1.09 and

1.13 (d, J _HH) 6.9, CH(CH₃)₂); 1.44,

1.66, and 1.96 (m, CH₂); 2.15 (m, CH);

2.53 (m, CH(CH₃)₂); 6.48-7.51 (m, Ph)

0.32, 0.75, 1.26, and 2.12 (s, CH₃); 1.18,

1.53, and 1.62 (m, CH₂); 1.96 (m, CH);

6.89-7.49 (m, Ph)

37.94 d

R ) ⁱPr (14b) 35.35 d 22.6 5.60 br 6.08 br 5.30 m, b

5.15 s

2.52 d^d

2.71 d^d

37.92 d

R ) Me (14c) 35.23 d 22.8 5.17 br 6.43 br 5.31 d,^e5.56 d,^fb

5.05 s

1.75 d^g

2.53 d^g

38.09 d

5.58 br

a

Spectra recorded in CDCl₃; δ in ppm and J in Hz. Abbreviations: s, singlet; br, broad; d, doublet; sept, septuplet; m, multiplet.

b

c

d

e

f

g

Overlapped by Ph protons. J _HH) 18.8. J _HH) 19.1. J _HH) 8.0. J _HH) 9.4. J _HH) 18.5.

do not undergo such cyclization processes, even in

refluxing toluene. It is apparent that the electron-

releasing ability of the indenyl moiety [Ru(η⁵-C₉H₇)-

(PPh₃)₂] decreases the electrophilic character of the

vinylidene RudC_Rmoiety, avoiding the effective cycliza-

tion reaction.¹⁶To facilitate this process, we set out to

Additions of Enolates on Ru(II) Indenyl Allenylidenes

Organometallics, Vol. 20, No. 14, 2001 3183

Ta ble 10. ¹³C{¹H} NMR Da ta for Ca tion ic Vin ylid en e Com p lexes

[Ru {dCdC(H)C(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(P P h ₃)₂][BF ₄]^a

η⁵-C₉H₇

C-2 C-3a,7a ∆δ(C-3,7a)^bC-4,5,6,7 RudC_R²J _CP

complex C-1,3

C_â

C_γCH₂CdO CdO

others

14a

79.96 d^c97.27 113.67

81.65 d^d

119.88

-13.92

122.04 328.79 dd 19.5 108.87 57.49

44.53

199.98 18.80, 26.85, and 27.02

(s, CH₃); 25.27, 35.08,

and 41.06 (s, CH₂);

124.59

14.6

e

46.47 and 52.71 (s, C);

49.77 (s, CH); 127.62-

136.67 (m, Ph)

14b

80.41 d^f97.55 113.59

82.30 d^g

121.07

-13.37

122.40 328.57 dd 18.9 109.05 59.29

46.65

216.15 18.83, 19.02, 19.43,

27.63, and 27.96 (s,

124.31

14.8

e

CH₃); 26.14, 35.67,

and 41.47 (s, CH₂);

42.42 (s, CH(CH₃)₂);

46.84 and 53.11 (s, C);

50.19 (s, CH); 125.37-

135.91 (m, Ph)

14c

80.36 d^f97.65 113.53

82.29 d^f

121.02

-13.42

122.39 328.25 dd 18.7 108.94 58.52

49.36

210.28 18.91, 26.95, 27.74, and

31.38 (s, CH₃); 25.99,

35.45, and 41.40 (s,

125.34

14.1

e

CH₂); 46.92 and 52.78

(s, C); 50.13 (s, CH);

128.51-147.47 (m, Ph)

a

b

Spectra recorded in CD₂Cl₂; δ in ppm and J in Hz. Abbreviations: s, singlet; d, doublet; dd, doublet of doublets; m, multiplet. ∆δ(C-

3a,7a) ) δ(C-3a,7a(η-indenyl complex)) - δ(C-3a,7a(sodium indenyl)), δ(C-3a,7a) for sodium indenyl 130.70 ppm. ²J _CP) 8.5. ²J _CP

)

c

d

7.3. ^eOverlapped by Ph carbons. ²J _CP) 8.2. ²J _CP) 7.7.

f

g

were prepared. Thus, treatment of [Ru{CtCCPh₂(CH₂-

COR²)}(η⁵-C₉H₇)(PPh₃)₂] (R²) Ph (3a ), ⁱPr (3b)) with a

slight excess of LiMe in tetrahydrofuran, at -20 °C, and

subsequent methanolysis allows the preparation of the

γ-hydroxy-alkynyl derivatives [Ru(CtCCPh₂{CH₂C-

(OH)MeR²})(η⁵-C₉H₇)(PPh₃)₂] (16a ,b; 71% and 63%

yields, respectively) (Scheme 4). We note that all at-

tempts to promote related reactions on the correspond-

ing vinylidene complexes 5a ,b were unsuccessful, re-

covering instead the starting σ-alkynyl derivatives 3a ,b.

Complexes 16a ,b have been analytically and spectro-

scopically characterized (see the Experimental Section).

IR and ¹³C{¹H} NMR spectra are very informative, since

they show the disappearance of the typical carbonyl

signals of 3a ,b, confirming the reduction of the ketone

group. In addition, two novel singlet resonances in the

ranges δ 25.49-32.09 and 75.53-75.91 assigned to the

methyl and C-OH carbon nuclei, respectively, were

observed in the ¹³C{¹H} NMR spectra. However, pro-

tonation of 16a ,b does not yield the expected cyclic

carbenes 17 (Scheme 5), giving instead the tetrafluo-

roborate salt of the diphenylallenylidene complex [Ru-

(dCdCdCPh₂)(η⁵-C₉H₇)(PPh₃)₂]⁺(1) in almost quanti-

tative yields. Apparently, the protonation of the alkynyl

moiety in 16a ,b seems to be thermodynamically disfa-

vored with respect to the protonation of the hydroxy

function. Thus, an unstable carbocation is formed, which

evolves into 1 by elimination of R-methylstyrene or 2,3-

dimethyl-1-butene (Scheme 5).

F igu r e 1. ORTEP view of the structure of the σ-alkynyl

complex [Ru{CtCC(C₉H₁₆)(CH₂COⁱPr)}(η⁵-C₉H₇)(PPh₃)₂]

(13b). Aryl groups of the triphenylphosphine ligands have

been omitted for clarity. Selected bond lengths (Å) and

angles (deg): Ru-C* ) 1.94(4); Ru-P1 ) 2.235(8);

Ru-P2 ) 2.333(9); Ru-C1 ) 2.03(3); C1-C2 ) 1.21(3);

C2-C3 ) 1.55(4); C5-O1 ) 1.18(5); C*-Ru-P1 ) 119(1);

C*-Ru-P2 ) 123(1); C*-Ru-C1 ) 121(3); Ru-C1-C2 )

173(3); C(1)-C(2)-C(3) ) 168(3). C* ) centroid of the

indenyl ring (C18, C19, C20, C21, C22).

Consequently, an alternative synthetic procedure was

devised. As it is well-known, Lewis acid catalyzed

intramolecular heterocyclizations of alkynes is a widely

used and general method for the synthesis of unsatur-

ated heterocycles.¹⁷This synthetic methodology proved

to be appropriate to obtain the desired cyclization

products. Thus, we have found that the treatment of

synthesize hydroxy-vinylidene complexes via reduction

of the ketone group into the corresponding alcohol.

Toward this aim the corresponding σ-alkynyl precursors

(16) In contrast, the protonation of the analogous keto-substituted

σ-alkynyl complex [Ru{CtCCPh₂(CH₂COCH₃)}(η⁵-C₅H₅)(CO)(PⁱPr₃)]

with HBF₄has been reported to give [Ru{dCCH₂CPh₂CHdC(CH₃)-

O}(η⁵-C₅H₅)(CO)(PⁱPr₃)][BF₄], which is formed via an intramolecular

nucleophilic addition at the electrophilic C_Ratom of the enol resonance

form in the highly reactive vinylidene intermediate [Ru{dCdC(H)-

CPh₂(CH₂COCH₃)}(η⁵-C₅H₅)(CO)(PⁱPr₃)][BF₄].^2d

(17) See for example: Harding, K. E.; Tiner, T. H. In Comprehensive

Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press:

Oxford, U.K., 1991; Vol. 4, p 363.

3184 Organometallics, Vol. 20, No. 14, 2001

Ta ble 11. IR^aa n d ¹H NMR^bDa ta for Ter m in a l Alk yn es HCtCC(C₉H₁₆)(CH₂COR)

Cadierno et al.

IR

¹H

compd

ν(HCt)

ν(CtC)

2099

ν(CdO)

HCt

CH₂

others

R ) Ph (15a )

3307

1692

2.03 s

3.05 d^c

3.16 d^c

2.44 d^d

2.60 d^d

0.96, 1.07, and 1.65 (s, CH₃); 1.00 and 1.82 (m, CH₂); 1.12-1.56

(m, CH₂); 2.52 (m, CH); 7.04-7.85 (m, Ph)

0.92 and 0.94 (d, J _HH) 6.8, CH(CH₃)₂); 0.93 and 1.02 (s, CH₃);

0.98-1.52 (m, CH₃and CH₂); 2.23 (sept, J _HH) 6.8, CH(CH₃)₂);

2.43 (m, CH)

R ) ⁱPr (15b)

3316

2104

2103

1725

1718

1.98 s

2.00 s

R ) Me (15c)

3257

2.29 d^d

2.39 d^d

0.87, 0.95, 1.45, and 1.71 (s, CH₃); 1.06, 1.31, and 1.50 (m, CH₂);

2.38 (m, CH)

a

b

KBr; ν in cm^-1

.

Spectra recorded in C₆D₆; δ in ppm and J in Hz. Abbreviations: s, singlet; d, doublet; sept, septuplet; m, multiplet.

^cJ _HH) 18.1. J _HH) 17.9.

d

Ta ble 12. ¹³C{¹H} NMR Da ta for Ter m in a l Alk yn es HCtCC(C₉H₁₆)(CH₂COR)^a

compd

tCH

tC

C_γ

CH₂CdO

CdO

others

15a

72.72

87.49

52.92

45.23

197.06

18.62, 25.93, and 26.70 (s, CH₃); 25.11, 34.28, and 40.99 (s, CH₂); 43.97

and 49.42 (s, C); 51.32 (s, CH); 127.97, 128.60, and 132.45 (s, CH of Ph);

138.31 (s, C of Ph)

15b

15c

72.44

72.71

87.55

87.40

52.69

52.70

47.10

49.81

210.57

204.60

18.48, 18.51, 18.87, 25.81, and 28.68 (s, CH₃); 25.09, 34.24, and 40.91

(s, CH₂); 40.97 (s, CH(CH₃)₂), 43.69 and 49.18 (s, C); 51.16 (s, CH)

18.36, 25.95, 26.66, and 30.24 (s, CH₃); 25.09, 34.07, and 40.80 (s, CH₂);

43.80 and 49.20 (s, C); 51.11 (s, CH)

a

Spectra recorded in C₆D₆; δ in ppm.

Sch em e 4

Sch em e 5

σ-alkynyl complexes [Ru{CtCCPh₂(CH₂COR²)}(η⁵-C₉-

H₇)(PPh₃)₂] (3a ,b) with ca. 5 mol % AlCl₃in dichloro-

methane at room temperature smoothly produces the

(i) (¹H NMR) two doublets (ca. J _HH) 2 Hz) in the range

4.74-5.57 ppm assigned to the olefinic protons of the

six-membered ring and (ii) (¹³C{¹H} NMR) a triplet

2

signal (ca. J _CP) 17 Hz) at ca. 163 ppm for the Ru-C_R

cyclic alkenyl complexes [Ru{CdCHCPh₂CHdC(R²)O}-

(η⁵-C₉H₇)(PPh₃)₂] (18a ,b; 95% and 87% yields, respec-

tively) (Scheme 6). These reactions can be monitored by

IR spectroscopy, which shows the total disappearance

of the typical ν(CtC) and ν(CdO) absorptions of 3a ,b.

In the NMR spectra, the most noticeable resonances are

atom¹⁸and singlets for the dCH (δ 99.50-117.64) and

dC (δ 151.42-157.67) carbons.

As expected from the ability of alkenyl complexes to

undergo electrophilic additions at the C_âatom to give

carbene derivatives,^18,19treatment of THF solutions of

18a ,b with HBF₄at -20 °C leads to the formation of

Additions of Enolates on Ru(II) Indenyl Allenylidenes

Organometallics, Vol. 20, No. 14, 2001 3185

Sch em e 6

Sch em e 7

gylic alcohols with ketones containing R-hydrogens via

[Co₂(CO)₆]-stabilized propargylium ions, which also

yields γ-keto-substituted alkynes.²⁰

the air-stable oxacycloalkylidenes [Ru{dCCH₂CPh₂-

CHdC(R²)O}(η⁵-C₉H₇)(PPh₃)₂][BF₄] (R²) Ph (19a ), ⁱPr

(19b)), which have been isolated in 83 and 89% yields,

respectively (Scheme 6). The presence of the carbenic

moiety is clearly confirmed by the ¹³C{¹H} NMR spectra,

which show the typical low-field resonance of the

carbenic carbon nuclei at ca. δ 302 (t, ²J _CP) 11.8-14.3

Hz). The spectra also show resonances assignable to the

CH₂(δ 67.62-68.39), dCH (δ 109.14-115.39), dC (δ

153.48-160.68), and CPh₂(δ 43.60-44.71) carbons of

the six-membered heterocyclic skeletons.

To extend the scope of this synthetic route to optically

active cyclic carbene complexes, we examined the be-

havior of the analogous chiral keto-alkynyl derivative

13a toward AlCl₃. Under analogous reaction conditions,

the chiral oxacycloalkenyl complex 20 was obtained and

isolated (78% yield) as an air-stable solid. The subse-

quent protonation in THF with HBF₄at -20 °C gives

the desired oxacyclocarbene complex 21 in 83% yield

(Scheme 7). Since the analytical and spectroscopic data

of 20 and 21 are comparable to those observed for their

achiral counterparts, 18a ,b and 19a ,b will not be

further discussed.

The synthetic procedure is based on the electronic

and/or steric ability of the fragment [Ru(η⁵-C₉H₇)-

(PPh₃)₂] to promote the following processes involved in

the synthetic route. (i) Stabilization of the coordinated

allenylidene groups CdCdCR₂which results from the

dehydration of propargylic alcohols HCtCC(OH)R₂. (ii)

The regioselective addition of lithium enolates derived

from methyl ketones at the C_γatom of the allenylidene

chain to give the keto-alkynyl complexes [Ru{CtCC-

R₂(CH₂COR)}(η⁵-C₉H₇)(PPh₃)₂] (3a -e and 4a -d ). The

steric protection of the electrophilic C_Rallows the

nucleophilic addition at the more accessible C_γatom.

(iii) The elimination of the free γ-keto-substituted

alkyne HCtCCR₂(CH₂COR) (7a -e and 8a -d ) which

can be efficiently achieved via selective C_âprotonation

of 3a -e and 4a -d to afford vinylidene complexes [Ru-

{dCdC(H)CR₂(CH₂COR)}(η⁵-C₉H₇)(PPh₃)₂]⁺(5a -e and

6a -d ), followed by the vinylidene-π-terminal alkyne

tautomerization in refluxing acetonitrile, generating the

species [Ru{η²-HCtCCR₂(CH₂COR)}(η⁵-C₉H₇)(PPh₃)₂]⁺.

The ready exchange of the coordinated alkyne for

acetonitrile leads to the free alkynes and the quantita-

tive recovery of the metal fragment as the acetonitrile

complex [Ru(NtCMe)(η⁵-C₉H₇)(PPh₃)₂][BF₄] (9).

Con clu d in g Rem a r k s

In this work a metal-mediated synthetic approach for

γ-keto-substituted alkynes HCtCCR₂(CH₂COR), which

result from the formal coupling of 2-propyn-1-ols with

methyl ketones, is reported. This methodology consti-

tutes an alternative to the known coupling of propar-

The generality of this synthetic procedure is shown

by the synthesis of chiral γ-keto-alkynes 15a -c, which

are obtained from the formal coupling of 2-exo-ethynyl-

1,3,3-trimethyl-2-endo-norbornanol (11) with methyl

ketones. Thus, the synthesis of the first optically active

allenylidene derivative, [Ru{dCdCdC(C₉H₁₆)}(η⁵-C₉H₇)-

(18) These chemical shifts and coupling constants are comparable

to those found in related ruthenium(II) indenyl alkenyl derivatives [Ru-

{C(R)dC(H)R′}(η⁵-C₉H₇)L₂] (L ) PPh₃; L₂) dppm): (a) Bassetti, M.;

Casellato, P.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Bernardo, C.;

Mart´ın-Vaca, B. Organometallics 1997, 16, 5470. (b) Gamasa, M. P.;

Gimeno, J .; Mart´ın-Vaca, B. M. Organometallics 1998, 17, 3707. See

also ref 5c.

(20) For general reviews on the synthetic utility of metal-complexed

propargyl cations see: (a) Nicholas, K. M. Acc. Chem. Res. 1987, 20,

207. (b) Smit, W. A.; Caple, R.; Smoliakova, I. P. Chem. Rev. 1994, 94,

2359. (c) McGlinchey, M. J .; Girard, L.; Ruffolo, R. Coord. Chem. Rev.,

1995, 143, 331. (d) Amouri, H.; Gruselle, M. Chem. Rev. 1996, 96, 1077.

(e) Melikyan, G. G.; Nicholas, K. M. In Modern Acetylene Chemistry;

Stang, P. J ., Diederich, F., Eds.; VCH: New York, 1995.

(19) For theoretical calculations on transition-metal alkenyl com-

plexes see: Kostic, N. M.; Fenske, R. F. Organometallics 1982, 1, 974.

3186 Organometallics, Vol. 20, No. 14, 2001

Cadierno et al.

2092 (CtC). Anal. Calcd for RuC₅₉H₅₂P₂O (940.07): C, 75.38;

H, 5.57. Found: C, 74.92; H, 5.48. 4c: yield 71% (0.647 g); IR

(KBr, cm^-1) ν 1709 (CdO), 2089 (CtC). Anal. Calcd for

RuC₅₇H₄₈P₂O (912.03): C, 75.06; H, 5.30. Found: C, 75.21; H,

5.17. 4d : yield 69% (0.746 g); IR (KBr, cm^-1) ν 1658 (CdO),

2092 (CtC). Anal. Calcd for RuFeC₆₆H₅₄P₂O (1082.01): C,

73.26; H, 5.03. Found: C, 72.91; H, 5.18.

(PPh₃)₂][PF₆] (12), is reported. This precursor has also

proven to be an excellent substrate to promote regio-

and diastereoselective additions of enolates [CH₂COR]^-,

allowing, therefore, the diastereoselective synthesis of

the final terminal alkynes of interest as building blocks

in organic synthesis.

Moreover, a novel and general synthetic strategy for

the preparation of unsaturated cyclic alkenyl and car-

bene ruthenium(II) complexes from γ-keto-alkynyl

derivatives [Ru{CtCCR₂(CH₂COR)}(η⁵-C₉H₇)(PPh₃)₂]

has also been described. These alkynyl species are able

to undergo AlCl₃-catalyzed intramolecular cyclization

reactions to give oxacycloalkenyl complexes: i.e., 18a ,b

and 20. The subsequent protonation gives oxacyclocar-

bene complexes, i.e. 19a ,b and 21, in high yields.

Further studies concerning the scope and limitations

of these processes are in progress.^5e

(b) Syn th esis of Vin ylid en e Com p lexes [Ru {dCdC-

(H)C(R¹)P h (CH₂COR²)}(η⁵-C₉H₇)(P P h ₃)₂][BF ₄] (R¹) P h ,

i

R²) P h (5a ), P r (5b), Me (5c), (η⁵-C₅H₄)F e(η⁵-C₅H₅) (5d ),

i

(E)-CHdCHP h (5e); R¹) H, R²) P h (6a ), P r (6b), Me

(6c), (η⁵-C₅H₄)F e(η⁵-C₅H₅) (6d )). A diluted solution of HBF₄‚

Et₂O in diethyl ether was added dropwise at -20 °C to a

stirred solution of the corresponding σ-alkynyl complex [Ru-

{CtCC(R¹)Ph(CH₂COR²)}(η⁵-C₉H₇)(PPh₃)₂] (3a -e and 4a -d ;

1 mmol) in 100 mL of diethyl ether. Immediately, an insoluble

solid precipitated but the addition was continued until no

further solid was formed. The solution was then decanted and

the brown solid washed with diethyl ether (3 × 20 mL)

and vacuum-dried. 5a : yield 88% (1.001 g); IR (KBr, cm^-1

)

ν 1065 (BF₄^-), 1689 (CdO). Anal. Calcd for RuC₆₈H₅₅F₄P₂BO

(1138.00): C, 71.77; H, 4.87. Found: C, 71.08; H, 5.06. 5b:

yield 89% (0.982 g); IR (KBr, cm^-1) ν 1061 (BF₄^-), 1710 (Cd

O). Anal. Calcd for RuC₆₅H₅₇F₄P₂BO (1103.98): C, 70.72; H,

5.20. Found: C, 69.95; H, 5.06. 5c: yield 87% (0.935 g); IR

(KBr, cm^-1) ν 1059 (BF₄^-), 1712 (CdO). Anal. Calcd for

RuC₆₃H₅₃F₄P₂BO (1075.43): C, 70.33; H, 4.96. Found: C, 70.12;

H, 4.81. 5d : yield 88% (1.096 g); IR (KBr, cm^-1) ν 1061 (BF₄^-),

1660 (CdO). Anal. Calcd for RuFeC₇₂H₅₉F₄P₂BO (1245.92): C,

69.41; H, 4.77. Found: C, 69.45; H, 4.95. 5e: yield 82%

(0.954 g); IR (KBr, cm^-1) ν ) 1057 (BF₄^-), 1662 (CdO). Anal.

Calcd for RuC₇₀H₅₇F₄P₂BO (1064.04): C, 72.22; H, 4.93.

Found: C, 72.79; H, 4.93. 6a : yield 89% (0.945 g); IR (KBr,

cm^-1) ν 1058 (BF₄^-), 1657 (CdO). Anal. Calcd for RuC₆₂H₅₁F₄P₂-

BO (1061.90): C, 70.12; H, 4.84. Found: C, 70.52; H, 4.52.

6b: yield 84% (0.863 g); IR (KBr, cm^-1) ν 1060 (BF₄^-), 1705

(CdO). Anal. Calcd for RuC₅₉H₅₃F₄P₂BO (1027.88): C, 68.94;

H, 5.20. Found: C, 68.51; H, 5.23. 6c: yield 94% (0.940 g); IR

(KBr, cm^-1) ν 1060 (BF₄^-), 1712 (CdO). Anal. Calcd for

RuC₅₇H₄₉F₄P₂BO (999.84): C, 68.47; H, 4.94. Found: C, 68.52;

H, 4.88. 6d : yield 74% (0.866 g); IR (KBr, cm^-1) ν 1061 (BF₄^-),

1654 (CdO). Anal. Calcd for RuFeC₆₆H₅₅F₄P₂BO (1169.82): C,

67.76; H, 4.73. Found: C, 68.02; H, 4.69.

Exp er im en ta l Section

The manipulations were performed under an atmosphere

of dry nitrogen using vacuum-line and standard Schlenk

techniques. All reagents were obtained from commercial

suppliers and used without further purification. Solvents were

dried by standard methods and distilled under nitrogen before

use. Compounds [Ru{dCdCdC(R¹)Ph}(η⁵-C₉H₇)(PPh₃)₂][PF₆]

(R¹) Ph (1), H (2)),^5a[RuCl(η⁵-C₉H₇)(PPh₃)₂] (10),¹²and 2-exo-

ethynyl-1,3,3-trimethyl-2-endo-norbornanol (11)¹³were pre-

pared by following the methods reported in the literature.

Infrared spectra were recorded on a Perkin-Elmer 1720-XFT

spectrometer. The C and H analyses were carried out with a

Perkin-Elmer 2400 microanalyzer. High-resolution mass spec-

tra were recorded using a MAT-95 spectrometer. NMR spectra

were recorded on a Bruker AC300 instrument at 300 MHz (¹H),

121.5 MHz (³¹P), or 75.4 MHz (¹³C) using SiMe₄or 85% H₃-

PO₄as standards. DEPT experiments have been carried out

for all the compounds reported in this paper.

(a ) Syn th esis of σ-Alk yn yl Com p lexes [Ru {CtCC(R¹)-

P h (CH₂COR²)}(η⁵-C₉H₇)(P P h ₃)₂] (R¹) P h , R²) P h (3a ),

ⁱP r (3b), Me (3c), (η⁵-C₅H₄)F e(η⁵-C₅H₅) (3d ), (E)-CHdCHP h

i

(3e); R¹) H, R²) P h (4a ), P r (4b), Me (4c), (η⁵-C₅H₄)F e-

(η⁵-C₅H₅) (4d )). A solution of LiCH₂COR²(obtained in situ

by treatment of the corresponding ketone (1 mmol) with LDA

(0.179 g, 1 mmol) at -20 °C in 10 mL of THF for 30 min) was

added at -20 °C to a solution of [Ru{dCdCdC(R¹)Ph}(η⁵-

C₉H₇)(PPh₃)₂][PF₆] (R¹) Ph (1), H (2); 1 mmol) in 30 mL of

THF. The mixture was warmed to room temperature, and the

solvent was then removed in vacuo. The resulting solid residue

was dissolved in dichloromethane (ca. 5 mL) and transferred

to an Al₂O₃(neutral; activity grade I) chromatography column.

Elution with a mixture of hexane and diethyl ether (1/2) gave

an orange band from which σ-alkynyl complexes 3a -e and

4a -d were isolated as orange solids after solvent removal.

3a : yield 83% (0.871 g); IR (KBr, cm^-1) ν 1702 (CdO), 2075

(CtC). Anal. Calcd for RuC₆₈H₅₄P₂O (1050.19): C, 77.77; H,

5.18. Found: C, 77.33; H, 5.19. 3b: yield 65% (0.660 g); IR

(KBr, cm^-1) ν 1721 (CdO), 2086 (CtC). Anal. Calcd for

RuC₆₅H₅₆P₂O (1016.17): C, 76.83; H, 5.55. Found: C, 76.29;

H, 5.33. 3c: yield 63% (0.622 g); IR (KBr, cm^-1) ν 1697 (Cd

O), 2080 (CtC). Anal. Calcd for RuC₆₃H₅₂P₂O (988.13): C,

76.58; H, 5.30. Found: C, 76.46; H, 5.35. 3d : yield 78% (0.903

g); IR (KBr, cm^-1) ν 1679 (CdO), 2082 (CtC). Anal. Calcd for

RuFeC₇₂H₅₈P₂O (1158.11): C, 74.67; H, 5.05. Found: C, 75.27;

H, 5.28. 3e: yield 81% (0.871 g); IR (KBr, cm^-1) ν 1652 (Cd

O), 2052 (CtC). Anal. Calcd for RuC₇₀H₅₆P₂O (1076.23): C,

78.12; H, 5.24. Found: C, 77.91; H, 5.18. 4a : yield 62% (0.604

g); IR (KBr, cm^-1) ν 1706 (CdO), 2073 (CtC). Anal. Calcd for

RuC₆₂H₅₀P₂O (974.09): C, 76.45; H, 5.17. Found: C, 76.13; H,

5.09. 4b: yield 65% (0.611 g); IR (KBr, cm^-1) ν 1705 (CdO),

(c) Syn th esis of Ter m in a l Alk yn es HCtCC(R¹)P h -

i

(CH₂COR²) (R¹) P h , R²) P h (7a ), P r (7b), Me (7c), (η⁵-

C₅H₄)F e(η⁵-C₅H₅) (7d ), (E)-CHdCHP h (7e); R¹) H, R²

)

i

P h (8a ), P r (8b), Me (8c), (η⁵-C₅H₄)F e(η⁵-C₅H₅) (8d )). A

solution of the corresponding vinylidene complex [Ru{dCd

C(H)C(R¹)Ph(CH₂COR²)}(η⁵-C₉H₇)(PPh₃)₂][BF₄] (5a-e and 6a-

d ; 1 mmol) in acetonitrile (30 mL) was heated under reflux

for 30 min. The solution was then evaporated to dryness and

the resulting solid residue extracted with diethyl ether (ca.

50 mL) and filtered. A yellow solid containing mainly the

nitrile complex [Ru(NtCMe)(η⁵-C₉H₇)(PPh₃)₂][BF₄] (9) remains

insoluble. The extract was evaporated to dryness and the crude

product purified by column chromatography on silica gel with

a mixture of hexane and diethyl ether (6/1) as eluent. Evapo-

ration of the solvents gave terminal alkynes 7a -e and 8a -d .

7a : white solid; yield 86% (0.267 g). Anal. Calcd for C₂₃H₁₈

O

(310.94): C, 89.00; H, 5.84. Found: C, 88.91; H, 5.90. 7b: white

solid; yield 80% (0.221 g). Anal. Calcd for C₂₀H₂₀O (276.37):

C, 86.92; H, 7.29. Found: C, 86.45; H, 7.34. 7c: white solid;

yield 93% (0.231 g). Anal. Calcd for C₁₈H₁₆O (248.32): C, 87.06;

H, 6.49. Found: C, 86.91; H, 6.55. 7d : orange solid; yield 73%

(0.305 g). Anal. Calcd for FeC₂₇H₂₂O (418.31): C, 77.52; H,

5.30. Found: C, 77.27; H, 5.48. 7e: white solid; yield 78%

(0.262 g). Anal. Calcd for C₂₅H₂₀O (336.43): C, 89.25; H, 5.99.

Found: C, 89.12; H, 6.14. 8a : white solid; yield 82% (0.192

g). Anal. Calcd for C₁₇H₁₄O (234.30): C, 87.14; H, 6.02.

Found: C, 87.21; H, 6.12. 8b: white solid; yield 76% (0.152

g). Anal. Calcd for C₁₄H₁₆O (200.28): C, 83.96; H, 8.05.

Additions of Enolates on Ru(II) Indenyl Allenylidenes

Organometallics, Vol. 20, No. 14, 2001 3187

Found: C, 83.78; H, 8.10. 8c: colorless oil; yield 80% (0.138

g); HRMS m/z calcd for C₁₂H₁₂O (found) M⁺) 172.088 809

(172.088 527). 8d : orange solid; yield 72% (0.246 g). Anal.

Calcd for FeC₂₁H₁₈O (342.22): C, 73.70; H, 5.30. Found: C,

73.60; H, 5.22.

(h ) Syn th esis of σ-Alk yn yl Com p lexes [Ru (CtCCP h ₂-

i

{CH₂C(OH)MeR²})(η⁵-C₉H₇)(P P h ₃)₂] (R²) P h (16a ), P r

(16b)). LiMe (1.5 M in diethyl ether; 1 mL, 1.5 mmol) was

added at -20 °C to a solution of the corresponding σ-alkynyl

complex [Ru{CtCCPh₂(CH₂COR²)}(η⁵-C₉H₇)(PPh₃)₂] (R²) Ph

i

(3a ), Pr (3b); 1 mmol) in 20 mL of THF. The mixture was

(d ) Syn th esis of th e Allen ylid en e Com p lex [Ru {dCd

CdC(C₉H₁₆)}(η⁵-C₉H₇)(P P h ₃)₂][P F ₆] (12). To a solution of

[RuCl(η⁵-C₉H₇)(PPh₃)₂] (10; 0.776 g, 1 mmol) in 50 mL of

MeOH were added NaPF₆(0.336 g, 2 mmol) and 2-exo-ethynyl-

1,3,3-trimethyl-2-endo-norbornanol (11; 0.356 g, 2 mmol). The

reaction mixture was heated under reflux for 30 min. The

solvent was then removed under vacuum, the crude product

extracted with CH₂Cl₂, and the extract filtered. Concentration

of the resulting solution to ca. 5 mL followed by the addition

of 50 mL of diethyl ether precipitated a red solid, which was

washed with diethyl ether (2 × 20 mL) and dried in vacuo.

Yield: 80% (0.837 g). IR (KBr, cm^-1): ν 1963 (CdCdC), 838

(PF₆^-). Anal. Calcd for RuC₅₇H₅₃F₆P₃(1046.02): C, 65.45; H,

5.10. Found: C, 64.83; H, 5.09. ³¹P{¹H} NMR (CDCl₃): δ 47.09

stirred at -20 °C for 45 min, and MeOH (5 mL) was then

added. The resulting solution was warmed to room tempera-

ture, and the solvent was then removed in vacuo. The resulting

solid residue was extracted with hexane (ca. 80 mL) and

filtered. Evaporation of the solvent gave complexes 16a ,b as

orange solids. 16a : yield 71% (0.757 g); IR (KBr, cm^-1) ν 2065

(CtC), 3317 (O-H); ³¹P{¹H} NMR (C₆D₆) δ 50.70 and 51.91

2

1

(d, J _PP) 23.2 Hz) ppm; H NMR (C₆D₆) δ 1.61 (s, 3H, CH₃),

3.10 and 3.17 (d, 1H each, J _HH) 13.7 Hz, CH₂), 3.22 (br, 1H,

OH), 4.75 and 5.16 (br, 1H each, H-1 and H-3), 5.45 (br, 1H,

H-2), 6.61-8.04 (m, 49H, Ph and H-4, H-5, H-6 and H-7) ppm;

¹³C{¹H} NMR (C₆D₆) δ 32.09 (s, CH₃), 50.04 (s, C_γ), 54.02 (s,

CH₂), 71.71 and 73.02 (s, C-1 and C-3), 75.53 (s, C-OH), 96.48

2

(s, C-2), 104.29 (vt, J _CP

)

²J _CP′) 21.6 Hz, Ru-C_R), 110.48

2

1

and 47.21 (d, J _PP) 23.2 Hz) ppm. H NMR (CDCl₃): δ 1.04,

1.05, and 1.14 (s, 3H each, CH₃), 1.30, 1.54, 1.62, and 1.87 (m,

1H each, CH₂), 1.77 (m, 2H, CH₂), 2.27 (m, 1H, CH), 5.19 (br,

2H, H-1 and H-3), 5.35 (br, 1H, H-2), 6.28 and 6.36 (d, 1H each,

J _HH) 7.7 Hz, H-4, H-5, H-6 or H-7), 6.91-7.67 (m, 32H, Ph

and H-4, H-5, H-6 or H-7) ppm. ¹³C{¹H} NMR (CD₂Cl₂): δ

18.87, 25.19, and 26.51 (s, CH₃), 25.24, 34.38, and 44.95 (s,

CH₂), 47.72 (s, CH), 57.57 and 64.34 (s, C), 83.52 and 84.60

(br, C-1 and C-3), 98.10 (s, C-2), 112.55 and 114.07 (s, C-3a

and C-7a), 123.21, 124.09, 129.17, and 131.39 (s, C-4, C-5, C-6

and C-7), 123.21-135.27 (m, Ph), 183.24 (s, C_γ), 202.01 (s, C_â),

and 110.80 (s, C-3a and C-7a), 116.18 (s, C_â), 124.62-152.20

(m, Ph, C-4, C-5, C-6 and C-7) ppm; ∆δ(C-3a,7a) ) -20.06.

Anal. Calcd for RuC₆₉H₅₈P₂O (1066.23): C, 77.72; H, 5.48.

Found: C, 78.10; H, 5.31. 16b: yield 63% (0.650 g); IR (KBr,

cm^-1) ν 2062 (CtC), 3332 (O-H); ³¹P{¹H} NMR (C₆D₆) δ 50.30

2

1

and 52.10 (d, J _PP) 33.4 Hz) ppm; H NMR (C₆D₆) δ 1.08 (d,

3H, J _HH) 8.2 Hz, CH(CH₃)₂), 1.11 (s, 3H, CH₃), 1.23 (d, 3H,

J _HH) 6.7 Hz, CH(CH₃)₂), 1.95 (m, 1H, CH(CH₃)₂), 2.86 (br,

2H, CH₂), 3.52 (br, 1H, OH), 4.50 and 5.25 (br, 1H each, H-1

and H-3), 5.40 (br, 1H, H-2), 6.42-7.83 (m, 44H, Ph and H-4,

H-5, H-6 and H-7) ppm; ¹³C{¹H} NMR (C₆D₆) δ 18.25 and 18.91

(s, CH(CH₃)₂), 25.49 (s, C(CH₃)OH), 42.10 (s, CH(CH₃)₂), 47.92

(s, C_γ), 49.42 (s, CH₂), 71.97 and 74.14 (s, C-1 and C-3), 75.91

2

305.06 (vt, J _CP) J _CP′) 18.9 Hz, RudC_R) ppm; ∆δ(C-3a,7a)

) -17.39.

(e) Syn th esis of σ-Alk yn yl Com p lexes [Ru {CtCC-

(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(P P h ₃)₂] (R ) P h (13a ), ⁱP r

(13b), Me (13c)). These complexes were prepared as described

for 3a -e and 4a -d by starting from the allenylidene deriva-

tive [Ru{dCdCdC(C₉H₁₆)}(η⁵-C₉H₇)(PPh₃)₂][PF₆] (12; 1.046 g,

1 mmol) and the corresponding ketone (1 mmol). Products were

purified by column chromatography on Al₂O₃(neutral; activity

grade I) with a mixture of hexane and diethyl ether (1/1) as

eluent. Evaporation of the solvents gave complexes 13a -c as

red solids. 13a : yield 77% (0.785 g); IR (KBr, cm^-1) ν 2070

(CtC), 1694 (CdO). Anal. Calcd for RuC₆₅H₆₀P₂O (1020.22):

C, 76.52; H, 5.94. Found: C, 76.56; H, 6.29. 13b: yield 68%

(0.670 g); IR (KBr, cm^-1) ν 2070 (CtC), 1718 (CdO). Anal.

Calcd for RuC₆₂H₆₂P₂O (986.20): C, 75.51; H, 6.33. Found: C,

75.47; H, 6.60. 13c: yield 76% (0.728 g); IR (KBr, cm^-1) ν 2072

(CtC), 1723 (CdO). Anal. Calcd for RuC₆₀H₅₈P₂O (958.15): C,

75.21; H, 6.10. Found: C, 74.86; H, 6.21.

2

(s, C-OH), 97.09 (s, C-2), 105.45 (vt, J _CP) J _CP′) 23.4 Hz,

Ru-C_R), 111.30 (s, C-3a and C-7a), 115.98 (s, C_â), 125.91-

152.71 (m, Ph, C-4, C-5, C-6 and C-7) ppm; ∆δ(C-3a,7a) )

-20.40. Anal. Calcd for RuC₆₆H₆₀P₂O (1032.22): C, 76.79; H,

5.85. Found: C, 77.01; H, 5.90.

(i) Syn th esis of Alk en yl Com p lexes [Ru {CdCHCP h ₂-

i

CHdC(R²)O}(η⁵-C₉H₇)(P P h ₃)₂] (R²) P h (18a ), P r (18b)).

A solution of the corresponding σ-alkynyl complex [Ru{Ct

i

CCPh₂(CH₂COR²)}(η⁵-C₉H₇)(PPh₃)₂] (R²) Ph (3a ), Pr (3b);

1 mmol) in 20 mL of dichloromethane was treated with

AlCl₃(0.007 g, 0.05 mmol) at room temperature for 2 h. The

solution was then evaporated to dryness and the resulting solid

residue extracted with diethyl ether (ca. 100 mL) and filtered

over Al₂O₃(neutral; activity grade I). Evaporation of the

solvent gave complexes 18a ,b as yellow solids. The labeling

scheme is

(f) Syn th esis of Vin ylid en e Com p lexes [Ru {dCdC-

(H)C(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(P P h ₃)₂][BF ₄] (R ) P h

i

(14a ), P r (14b), Me (14c)). These complexes were obtained

as brown solids as described for 5a -e and 6a -d , starting from

the corresponding σ-alkynyl complex [Ru{CtCC(C₉H₁₆)(CH₂-

COR)}(η⁵-C₉H₇)(PPh₃)₂] (13a -c) (1 mmol). 14a : yield 83%

(0.920 g); IR (KBr, cm^-1) ν 1663 (CdO), 1060 (BF₄^-). 14b: yield

85% (0.913 g); IR (KBr, cm^-1) ν 1702 (CdO), 1058 (BF₄^-).

14c: yield 96% (1.004 g); IR (KBr, cm^-1) ν 1711 (CdO), 1057

(BF₄^-). Complexes 14a -c were too sensitive to moisture and

oxygen to give satisfactory elemental analyses.

18a : yield 95% (0.997 g); ³¹P{¹H} NMR (C₆D₆) δ 49.44 (s) ppm;

¹H NMR (C₆D₆) δ 4.96 (br, 2H, H-1,3), 5.25 and 5.57 (d, 1H

each, J _HH) 2.4 Hz, dCH), 5.84 (m, 2H, H-4,7 or H-5,6), 5.93

(br, 1H, H-2), 6.69-7.48 (m, 47H, Ph and H-4,7 or H-5,6) ppm;

¹³C{¹H} NMR (CD₂Cl₂) δ 49.21 (s, C_γ), 74.25 (s, C-1,3), 100.94

(s, C-2), 106.39 and 117.64 (s, C_âand C_δ), 113.34 (s, C-3a,7a),

123.47 and 125.57 (s, C-4,7 and C-5,6), 127.74-152.74 (m, Ph),

(g) Syn th esis of Ter m in a l Alk yn es HCtCC(C₉H₁₆)-

(CH₂COR) (R ) P h (15a ), ⁱP r (15b), Me (15c)). These

compounds were prepared as described for 7a -e and 8a -d ,

starting from the corresponding vinylidene complex [Ru{dCd

C(H)C(C₉H₁₆)(CH₂COR)}(η⁵-C₉H₇)(PPh₃)₂][BF₄] (14a-c; 1 mmol).

2

151.42 (s, C_ꢀ), 163.86 (t, J _CP) 16.2 Hz, Ru-C_R) ppm; ∆δ(C-

15a : white solid; yield 79% (0.221 g). Anal. Calcd for C₂₀H₂₄

O

3a,7a) ) -17.36. Anal. Calcd for RuC₆₈H₅₄P₂O (1050.19): C,

77.77; H, 5.18. Found: C, 77.53; H, 5.07. 18b: yield 87% (0.884

g); ³¹P{¹H} NMR (C₆D₆) δ 50.10 (s) ppm; ¹H NMR (C₆D₆) δ

0.64 (d, 6H, J _HH) 6.8 Hz, CH₃), 1.64 (sept, 1H, J _HH) 6.8 Hz,

CH), 4.74 and 5.45 (d, 1H each, J _HH) 2.3 Hz, dCH), 4.89 (br,

2H, H-1,3), 5.73 and 6.76 (m, 2H each, H-4,7 and H-5,6), 5.86

(280.41): C, 85.67; H, 8.63. Found: C, 86.02; H, 8.84. 15b:

colorless oil; yield 70% (0.172 g); HRMS m/z calcd for C₂₀H₂₄

O

(found) M⁺246.198 869 (246.198 365). 15c: white solid; yield

97% (0.212 g). Anal. Calcd for C₁₅H₂₂O (218.34): C, 82.51; H,

10.15. Found: C, 81.73; H, 10.34.

3188 Organometallics, Vol. 20, No. 14, 2001

Cadierno et al.

(br, 1H, H-2), 6.99-7.50 (m, 40H, Ph) ppm; ¹³C{¹H} NMR (CD₂-

Cl₂) δ 20.96 (s, CH₃), 30.76 (s, CH), 48.33 (s, C_γ), 74.38 (s,

C-1,3), 99.50 and 116.84 (s, C_âand C_δ), 101.89 (s, C-2), 112.81

(s, C-3a,7a), 122.98 and 125.18 (s, C-4,7 and C-5,6), 127.45-

Ta ble 13. Cr ysta l Da ta a n d Str u ctu r e Refin em en t

for 13b

empirical formula

fw

RuC₆₂H₆₂P₂O‚2CH₂Cl₂

1155.98

2

153.17 (m, Ph), 157.67 (s, C_ꢀ), 162.65 (t, J _CP) 17.0 Hz, Ru-

temp

293(2) K

C_R) ppm; ∆δ(C-3a,7a) ) -17.89. Anal. Calcd for RuC₆₅H₅₆P₂O

(1016.17): C, 76.83; H, 5.55. Found: C, 77.01; H, 5.48.

wavelength

cryst syst

space group

0.710 73 Å

monoclinic

P2₁

(j) Syn th esis of Ca r ben e Com p lexes [Ru {CdCCH₂CHd

unit cell dimens

a

b

c

15.12(3) Å

C(R²)O}(η⁵-C₉H₇)(P P h ₃)₂] [BF ₄] (R²) P h (19a ), ⁱP r (19b)).

To a solution of the corresponding alkenyl complex 18a ,b (1

mmol) in 30 mL of THF was added dropwise, at -20 °C, an

excess of a diluted solution of HBF₄‚Et₂O in diethyl ether (3

mmol). The resulting solution was stirred at room temperature

for 30 min and then concentrated to ca. 5 mL. Addition of

diethyl ether (ca. 100 mL) precipitated complexes 19a ,b as

brown solids, which were washed with diethyl ether (3 × 20

mL) and vacuum-dried. The labeling scheme is

11.763(10) Å

18.574(14) Å

90°

R

â

112.85(9)°

γ

90°

V

Z

3045(6) Å³

2

density (calcd)

abs coeff

F(000)

cryst size

θ range for data collecn

index ranges

1.261 g cm^-3

0.524 mm^-1

1200

0.20 × 0.13 × 0.04 mm³

1.19-25.99°

-18 e h e 18, -14 e k e 14,

-22 e l e 22

13 029

no. of rflns collected

no. of indep rflns

completeness to θ ) 25.99°

abs cor

11 946 (R(int) ) 0.2370)

99.8%

empirical

max and min transmissn

refinement method

no. of data/restraints/params

goodness of fit on F²

final R indices (I > 2σ(I))

R indices (all data)

0.978 and 0.900

full-matrix least squares on F²

11 946/1/595

0.905

19a : yield 83% (0.944 g); IR (KBr, cm^-1) ν 1057 (BF₄^-); ³¹P{¹H}

NMR (CD₂Cl₂) δ 41.63 (s) ppm; H NMR (CD₂Cl₂) δ 3.79 (br,

1

2H, CH₂), 5.05 (d, 2H, J _HH) 1.7 Hz, H-1,3), 5.30 (t, 1H, J _HH

)

R1 ) 0.1073, wR2 ) 0.2366

R1 ) 0.4440, wR2 ) 0.3977

0.1(1)

1.7 Hz, H-2), 5.61 (br, 1H, dCH), 6.45-7.52 (m, 49H, Ph, H-4,7

and H-5,6) ppm; ¹³C{¹H} NMR (CD₂Cl₂) δ 44.71 (s, C_γ), 68.39

(s, C_â), 77.88 (s, C-1,3), 96.35 (s, C-2), 115.39 (s, C_δ), 117.88 (s,

C-3a,7a), 123.67 (s, C-4,7 or C-5,6), 127.36-144.94 (m, Ph and

absolute structure param

largest diff peak and hole

0.669 and -0.829 e Å^-3

2

C-4,7 or C-5,6), 153.48 (s, C_ꢀ), 303.11 (t, J _CP) 11.8 Hz, Rud

and C-3), 103.00 (s, C-2), 105.70 and 110.39 (s, C_âand C_δ),

113.31 and 115.65 (s, C-3a and C-7a), 122.34, 123.60, 124.50,

and 125.33 (s, C-4, C-5, C-6 and C-7), 126.99-138.70 (m, Ph),

C_R) ppm; ∆δ(C-3a,7a) ) -12.82. Anal. Calcd for RuC₆₈H₅₅F₄P₂-

BO (1138.00): C, 71.77; H, 4.87. Found: C, 72.15; H, 4.91.

19b: yield 89% (0.982 g); IR (KBr, cm^-1) ν ) 1060 (BF₄^-); ³¹P-

{¹H} NMR (CD₂Cl₂) δ 43.43 (s) ppm; ¹H NMR (CD₂Cl₂) δ 0.72

(d, 6H, J _HH) 6.8 Hz, CH₃), 1.89 (sept, 1H, J _HH) 6.8 Hz, CH),

3.53 (br, 2H, CH₂), 4.10 (br, 1H, dCH), 5.06 (d, 2H, J _HH) 2.3

Hz, H-1,3), 5.24 (t, 1H, J _HH) 2.3 Hz, H-2), 6.72-7.47 (m, 44H,

Ph, H-4,7 and H-5,6) ppm; ¹³C{¹H} NMR (CD₂Cl₂) δ 21.22 (s,

CH₃), 30.03 (s, CH), 43.60 (s, C_γ), 67.62 (s, C_â), 79.39 (s, C-1,3),

96.86 (s, C-2), 109.14 (s, C_δ), 117.06 (s, C-3a,7a), 123.51 (s,

C-4,7 or C-5,6), 127.40-145.36 (m, Ph and C-4,7 or C-5,6),

2

151.29 (s, C_ꢀ), 162.79 (vt, J _CP) 17.0 Hz, Ru-C_R) ppm; ∆δ(C-

3a,7a) ) -16.22. Anal. Calcd for RuC₆₅H₆₀P₂O (1020.22): C,

76.52; H, 5.94. Found: C, 76.93; H, 5.72.

(l) Syn th esis of th e Ca r ben e Com p lex [Ru dCCH₂C(C₉-

H₁₆)CHdCP h O(η⁵-C₉H ₇)(P P h ₃)₂][BF ₄] (21). This com-

plex was obtained as a brown solid as described for 19a ,b,

starting from alkenyl complex 20 (1.02 g, 1 mmol). The labeling

scheme is

2

160.68 (s, C_ꢀ), 301.48 (t, J _CP) 14.3 Hz, RudC_R) ppm; ∆δ(C-

3a,7a) ) -13.64. Anal. Calcd for RuC₆₅H₅₇F₄P₂BO (1103.98):

C, 70.72; H, 5.20. Found: C, 71.01; H, 5.12.

(k ) Syn th esis of th e Alk en yl Com p lex [Ru {CdCHC-

(C₉H₁₆)CHdCP h O}(η⁵-C₉H₇)(P P h ₃)₂] (20). This complex was

obtained as a yellow solid as described for 18a ,b, starting from

the σ-alkynyl complex [Ru{CtCC(C₉H₁₆)(CH₂COPh)}(η⁵-C₉H₇)-

(PPh₃)₂] (13a ) (1.02 g, 1 mmol). The labeling scheme is

Yield: 83% (0.920 g). IR (KBr, cm^-1): ν 1058 (BF₄^-). ³¹P{¹H}

NMR (CDCl₃): δ 39.58 and 44.23 (br) ppm. H NMR (CDCl₃):

1

δ 0.68, 0.94, and 1.02 (s, 3H each, CH₃), 1.19 (m, 2H, CH₂),

1.46-1.69 (m, 4H, CH₂), 2.32 (m, 1H, CH), 3.78 and 4.02 (br,

1H each, dCCH₂), 5.00 (br, 1H, dCH), 5.20 and 5.94 (m, 1H

each, H-4, H-5, H-6 or H-7), 5.31 (br, 1H, H-2), 5.48 (br, 2H,

H-1 and H-3), 6.26-7.48 (m, 37H, Ph and H-4, H-5, H-6 or

H-7) ppm. ¹³C{¹H} NMR (CDCl₃): δ 18.88, 24.87, and 28.11

(s, CH₃), 25.99, 29.19, and 40.91 (s, CH₂), 44.07, 46.01, and

52.17 (s, C and C_γ), 48.73 (s, CH), 59.81 (s, C_â), 75.89 (br, C-1

and C-3), 95.92 (s, C-2), 113.37 (s, C_δ), 121.51 (s, C-3a and

C-7a), 124.35, 125.28, and 127.42 (s, C-4, C-5, C-6 or C-7),

128.25-133.36 (m, Ph and C-4, C-5, C-6 or C-7), 151.13 (s,

Yield: 78% (0.796 g). ³¹P{¹H} NMR (C₆D₆): δ 47.03 and 49.85

2

(d, J _PP) 30.5 Hz) ppm. ¹H NMR (C₆D₆): δ 1.10, 1.18, and

1.28 (s, 3H each, CH₃), 1.24 and 1.83 (m, 2H each, CH₂), 1.57

and 1.96 (m, 1H each, CH₂), 2.19 (m, 1H, CH), 4.90 and 5.48

(d, 1H each, J _HH) 2.3 Hz, dCH), 5.12 and 5.18 (br, 1H each,

H-1 and H-3), 5.55 (m, 2H, H-4, H-5, H-6 or H-7), 6.13 (br,

1H, H-2), 6.26-6.86 (m, 37H, Ph and H-4, H-5, H-6 or H-7)

ppm. ¹³C{¹H} NMR (C₆D₆): δ 20.30, 25.60, and 28.69 (s, CH₃),

26.81, 29.39, and 40.63 (s, CH₂), 46.53, 48.80, and 53.95 (s, C

2

C_ꢀ), 302.45 (vt, J _CP) 12.5 Hz, RudC_R) ppm; ∆δ(C-3a,7a) )

-9.19. Complex 21 was too sensitive to moisture and oxygen

to give satisfactory elemental analyses.

X-r a y Diffr a ction . Data collection, crystal, and refinement

parameters are collected in Table 13. The unit-cell parameters

2

and C_γ), 49.47 (s, CH), 74.40 and 74.58 (d, J _CP) 9.8 Hz, C-1

Additions of Enolates on Ru(II) Indenyl Allenylidenes

Organometallics, Vol. 20, No. 14, 2001 3189

were obtained from the least-squares fit of 25 reflections with

θ between 5 and 8°. The intensity data were measured using

the ω-2θ scan technique and a variable scan rate, with a

maximum scan time of 60 s per reflection. The final drift

correction factors were between 0.90 and 0.98. On all reflec-

tions, profile analysis was performed.^21,22Lorentz and polar-

ization corrections were applied, and the data were reduced

squares cycle was 0.041. The final difference Fourier map

showed no peaks higher than 0.67 e Å^-3or deeper than -0.83

e Å^-3. The absolute configuration was determined with a Flack

parameter of 0.1(1).²⁵Atomic scattering factors were taken

from ref 26. Geometrical calculations were made with PARST.²⁷

The figure showing the coordination and the atomic numbering

scheme was drawn by PLATON.²⁸All calculations were

performed at the University of Oviedo on the Scientific

Computer Center and X-ray group DEC-ALPHA computers.

2

to F_ovalues. The structure was solved by Patterson methods

and phase expansion using the program DIRDIF²³and refined

by least squares using SHELXL97.²⁴The hydrogen atoms were

geometrically placed. During the final stages of the refinement,

the positional parameters and the anisotropic thermal param-

eters of most of the non-H atoms were refined, except for the

highly disordered carbon atoms (C6, C7, C8, C40 and C47) and

the molecules of CH₂Cl₂, which were isotropically refined. The

Ack n ow led gm en t. This work was supported by the

Direccio´n General de Investigacio´n Cient´ıfica y Te´cnica

(DGICYT, Project PB96-0558) and the EU (Human

Capital Mobility program, Project ERBCHRXCT 940501).

S.C. thanks the Ministerio de Educacio´n y Cultura

(MEC) for the award of a Ph.D. grant.

hydrogen atoms were isotropically refined riding with

a

common thermal parameter to CH₂Cl₂hydrogen atoms an

other to the rest. The function minimized was [∑w(F_o²- F_c²)²/

∑w(F_o²)²]^1/2, w ) 1/[σ²(F_o²) + (0.1353P)²+ (0.0000P)] where

P ) (Max(F_o²,0) + 2F_c²)/3 with σ(F_o²)²from counting statistics.

The maximum shift-to-esd ratio in the last full-matrix least-

Su p p or tin g In for m a tion Ava ila ble: Crystal structure

data for 13b, including tables of atomic parameters, anisotro-

pic thermal parameters, and bond distances and bond angles.

This material is available free of charge via the Internet at

http://pubs.acs.org.

(21) Grant, D. F.; Gabe, E. J . J . Appl. Crystallogr. 1978, 11, 114.

(22) Lehman, M. S.; Larsen, F. K. Acta Crystallogr., Sect. A 1974,

30, 580.

OM010252O

(23) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;

Garc´ıa-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The

DIRDIF Program System; Technical Report of the Crystallographic

Laboratory; University of Nijmegen, Nijmegen, The Netherlands, 1992.

(24) Sheldrick, G. M. SHELX97: Programs for Crystal Structure

Analysis; Institu¨t fu¨r Anorganische Chemie der Universita¨t, Tam-

manstrasse 4, D-3400 Go¨ttingen, Germany, 1998.

(25) Flack, H. D. Acta Crystallogr., Sect. A 1983, 39, 876.

(26) International Tables for X-ray Crystallography; Kynoch Press:

Birmingham, U.K., 1974; Vol. IV.

(27) Nardelli, M. Comput. Chem. 1983, 7, 95.

(28) Spek, A. L. PLATON, A Multipurpose Crystallographic Tool;

University of Utrecht, Utrecht, The Netherlands, 2001.

Article Doi

Efficient synthetic routes to terminal γ-keto-alkynes and unsaturated cyclic carbene complexes based on regio- and diastereoselective nucleophilic additions of enolates on ruthenium(II) indenyl allenylidenes

DOI: 10.1021/om010252o

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