SOME NEW REACTIONS OF PHENYLYTTERBIUM IODIDE

A. B. Sigalov, E. S. Petrov, and I. P. Beletskaya UDC 542.91:547.559.66'151

In our study of the reactions of phenyl derivatives of lanthanides similar to Grignard reagents, PhLnI (Ln = Ce, Sm, Eu, and Yb) with carbonyl compounds [i, 2] and vinyl bromide [3], we established that the best results are obtained from ytterbium derivatives. In a study of the reactions of PhYbI with carbonyl compounds in THF, we found conditions giving deoxygenation in the carbinolate addition product by the action of excess organolanthanide compound [2].

In the present work, we showed that an analogous transformation occurs in the reaction of PhYbI with anthraquinone. For any reagent ratio, the only reaction product is 9-phenylan- thracene (I); the product yield depends on the reagent ratio~ For PhYbI/anthraquinone = 4:1, the yield of (I) is 60%.

The reaction presumably proceeds through the following mechanism

O Ph OYbI II " ~ /

IL II - e h = o o b

\ .: f / i S\/\a/%<'-~Sxx?/']Y~I6 -'ilYb' /fJ\a/~']/%" + THF~:~'\("V%I

(A) c (1)

In a previous study of the reaction of PhYbI with benzophenone, we showed that the carbinolate formed undergoes reduction by excess PhYbI only with difficulty but may be converted quanti- tatively to triphenylmethane by the action of diphenyllithium, which is a stronger reducing agent [2]. The ease of step (b) in the reaction of PhYbI with anthraquinone is apparently related to the stability of anion A, while the facile deoxygenation of the second oxygen atom [step (c)] may be attributed to the rather facile electron transfer to the anthracene system. We note that the Grignard reagent PhMgBr, similar to PhLi, reacts with anthraqui- none to give a high yield of 9,10-dihydro-9,10-diphenyl-9,10-dihydroxyanthracene [4, 5].

The possibility of using organolanthanide compounds in transmetallation reactions was demonstrated for the reaction of PhYbI with perfluorovinyltributyltin leading to a 90% yield of PhSnBus

THF, 2o o C F 2 = C F S n B u ~ + P h Y b I - > PhSnBu3- i -CF2 = CFYbI

It was impossible to detect trifluorovinylytterbium iodide. This compound, similar to its lithium analog, apparently decomposes as a result of E-elimination of a fluoride ion.

The possibility of using organolanthanide compounds in nucleophilic aromatic substitu- tion reactions was demonstrated in the case of the reaction of PhYbI with hexafluorobenzene. C6FsPh was isolated in 65-70% yield.

THF, 3o o, 3 h PhYbI + C6Fe - - >- CsFsPh + Y b l F

L. Ya. Karpov Institute of Physical Chemistry, Moscow. Translated from Izvestiya Aka- demii Nauk SSSR, Seriya Khimicheskaya, No. I0, pp. 2386-2388, October, 1984. Original ar- ticle submitted January 17, 1984.

0568-5230/84/3310-2181508.50 �9 1985 Plenum Publishing Corporation 2181

According to Harper et al. [6], the analogous reaction with PhMgBr in THF at reflux leads to the formation of C6FsPh in 17% yield, while the reaction with PhLi in ether at re- flux gives 1,4-diphenyl-2,3,5,6-tetrafluorobenzene as a byproduct in addition to a 54% yield of C~FsPh [7].

EXPERIMENTAL

Phenylytterbium iodide was synthesized according to Evans et al. [8] with prior activa- tion of the metal in THF by the addition of 0.5-1.0 mole % CH212. All the reactions with prepared PhYbI were carried out in a dry argon atmosphere. The THF sample was purified by heating at reflux over Na/benzophenone and distilled immediately prior to use in the reac- tions. The reaction was monitored by thin-layer chromatography. In all the experiments, the reaction mixture was poured into 40 ml water, extracted with ether, and dried over Na2S04. After distilling off the solvent, the residue was subjected to preparative column chromatog- raphy on Chemapol silica gel (40-100 ~m) in hexane.

The PMR and 19F NMR spectra were taken on a Tesla BS-497 spectrometer in CCI~ solution with TMS as the standard for the PMR spectra and benzotrifluoride as the standard for the :gF NMR spectra.

Reaction of PhYbl with Anthraquinone. a) A sample of 0.62 g (2.98 mmoles) anthraqui- none was added to a solution of PhYbl obtained from 0.61 g (3.00 mmoles) iodobenzene and 0.61 g (3.50 mg-atom) ytterbium in 30 ml THF and stirred at 20~ for 3 h to give 0.19 g (0.75 mmole) (I) in 25% yield, mp 157~ [9]. PMR spectrum (6, ppm): 8.37 s (IH, H~~ 7.0- 8.2 m (13H, aromatic protons) [9].

b) A sample of 0.31 g (1.49 mmole) anthraquinone was added to a solution of PhYbl ob- tained-from 1.22 g (5.98 mmole) iodobenzene and 1.21 g (6.99 mg-atom) ytterbium in 30 ml THF and stirred for 3 h at 20~ to give 0.23 g (0.91 mmole) (I) in 60% yield, mp 157~

Reaction of PhYbl with Perfluorovinyltributyltin. A solution of 2.04 g (5.50 mmole) perfluorovinyltributyltin in i0 ml THF was added to a solution of PhYbl obtained from 1.22 g (5.98 mmole) iodobenzene and 1.21 g (6.99 g-atom) ytterbium in 30 ml THF and the mixture was stirred for 3 h to give 1.82 g (4.96 mmole) pheyltributyltin in 90% yield, n~ ~ 1.5151 [i0]. PMR spectrum (6, ppm): 7.6-8.0 m (5H, Ph), 0.6-1.6 m (27H, Bu).

Reaction of PhYbl with Hexafluorobenzene. A solution of 0.47 g (2.53 mmole) hexafluoro- benzene in 5 ml THF was added to a solution of PhYbl obtained from 0.61 g (3.00 mole) iodo- benzene and 0.61 g (3.50 mg-atom) ytterbium in 30 ml THF and stirred at 30~ for 3 h to give 0.42 g (1.72 mmole) 2,3,4,5,6-pentafluorodiphenyl in 68% yield, mp III~ [6]. PMR spectrum (6, ppm): 7.31 s (Ph), ~gF NMR spectrum (6, ppm): 100.1-100.5 m (2F, meta-fluorine atom), 93.74 t (IF, para-fluorine atom, J = 10.5 Hz), 80.76 d.d (2F, ortho fluorine atom, J1 = 8, J2 = 22 Hz).

CONCLUSIONS

]. The reaction of phenylytterbium iodide with anthraquinone leads to the formation of

9-phenylanthracene.

2. Phenylytterbium iodide reacts with hexafluorobenzene to give 2,3,4,5,6-pentafluoro-

diphenyl.

3. The possibility of using organolanthanide compounds in transmetallation reactions was demonstrated in the case of the reaction of phenylytterbium iodide with perfluorovinyl-

tributyltin.

LITERATURE CITED i. A. B. Sigalov, L. F. Rybakova, and I. P. Beletskaya, Izv. Akad. Nauk SSSR, Ser. Khim.,

1690 (1983). 2. A. B. Sigalov, E. S. Petrov, L. F. Rybakova, and I. P. Beletskaya, Izv. Akad. Nauk SSSR,

Ser. Khim., 2615 (1983). 3. A. B. Sigalov, L. F. Rybakova, and I. P. Beletskaya, Izv. Akad. Nauk SSSR, Ser. Khim.,

1692 (1983). 4. S. T. loffe and A. N. Nesmeyanov, Methods in Heteroorganic Chemistry. Magnesium,

Beryllium, Calcium, Strontium, and Barium [in Russian], Izd. Akad. Nauk SSSR, Moscow

(1963), p. 167.

2182

5. T. V. Talalaeva and K. A. Kocheshkov, Methods in Heteroorganic Chemistry, Book 2. Li- thium, Sodium, Potassium, Rubidium, and Cesium [in Russian], Nauka, Moscow (1971), p. 804.

6. R. I. Harper, E. J. Soloski, and C. Tamborski, J. Org. Chem., 29, 2385 (1964). 7. M. T. Chaudhry and R. Stephens, J. Chem. Soc., 4281 (1963)o 8. D. F. Evans, G. V. Fazakerley, and R. F. Phillips, J. Chem. Soc., A, 1931 (1971). 9. H. O. House, D. G. Keopsell, and W. J. Campbell, J. Org. Chem., 37, 1003 (1972).

i0. R. Ingham, S. Rosenberg, G. Gilman, and F. Rikens, Organotin and Organogermanium Com- pounds [Russian translation], Inostr. Lit.,Moscow (1962), p. 33.

HYDROGEN ISOTOPE EXCHANGE OF POLYMETHYLFERROCENES WITH ACIDS

A. I. Khatami, T. Kh. Kurbanov, I. R. Lyatifov, R. B. Materikova, and M. N. Nefedova

UDC 539.183.2:541.123.52

Polysubstituted sandwich compounds, in particular polymethylferrocenes, have been studied mainly relative to their oxidation--reduction characteristics and photochemistry [I, 2]. We have studied the accumulation of methyl groups in ferrocene on its capacity to undergo substitution. For this purpose, we measured the rate of hydrogen isotope exchange (HIE) of octamethylferrocene and 1,2,4',2',4'-hexamethylferrocene with acids.

The exchange rate constant (k) of octamethylferrocene in deuteroacetic acid at 25~ is 1.10-6sec -I. Ferrocene undergoes HIE with acetic acid only atl20-140~ [3], the value fork for ferrocene exchange at 25~ calculated using the data given by Sabbatini et al. [3} is 4oI0 -~ sec -I. If the value of k for ferrocene is taken as unity, then the relative exchange rate (kre I) of octamethylferrocene is 1.105 (taking into account that the number of exchangeable hydrogens in ferrocene is five times greater than in octamethylferrocene).

Hexamethylferrocene undergoes exchange at a somewhat lower rate than octamethylferro- cene. In a mixture of deuterated acetic and trifluoroacetic acids (Ho + l)k = 2.8-10 -~ sec -I, The value for k for ferrocene under the same conditions calculated using the dependence of the exchange rate on Ho [4] is 1-10 -7 sec -I Hence, Kre I for hexamethylferrocene is i~ ~ (also taking into account the statistical correction). As a control, the HIE of octamethylfer- rocene was also carried out at Ho + i. The value obtained, k = 2.10 -3 sec -I is somewhat underestimated due to the approximation of the HIE to the equilibrium position. The value obtained from these data for kre I is 5-10 ~, which is similar but somewhat less than for ex- change in acetic acid.

Thus, in accord with the electron-donor nature of the methyl groups, the introduction of six and eight methyl groups into ferrocene sharply increases the electrophilic isotope exchange of the ring hydrogens. However, this acceleration is less than expected from an additive substituent effect since the introduction of one methyl group increases the rate of HIE by one order of magnitude. [5].

EXPERIMENTAL

All the HIE experiments were carried out at 25 • 0.1~ in an argon atmosphere. A weighted sample of the compound was added in an argon stream to a 100-fold amount of acid and the mixture was brought to constant temperature. The mixture was treated with water after a given time interval and the compound was extracted with benzene and purified by sublimation in vacuum. The deuterium content was determined by mass spectroscopy using the AELITA program developed by the Mass Spectroscopy Group at the Institute of Heteroorganic Compounds of the Academy of Sciences of the USSR. The values for k were calculated assum- ing first-order kinetics [5]. The results obtained are given in Table i.

A. N. Nesmeyanov Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. i0, pp. 2389- 2390, October, 1984. Original article submitted January 17, 1984.

0568-5230/84/3310-2183508.50 �9 1985 Plenum Publishing Corporation 2183