CATALYTIC SYNTHESIS AND TRANSFORMATIONS OF MAGNESIUM-

CYCLOALKANES.

i. NEW CATALYTIC TRANSFORMATIONS IN THE SERIES OF MAGNESIUM-CYCLOPENTANES

U. M. Dzhemilev, R. M. Sultanov, R. G. Gaimaldinov, and G. A. Tolstikov

UDC 542.97:547.514+547.254.6: 547.538.141

The reactions of magnesium-cyclopentane with styrene and of 2,4-diphenylmagne- sium-cyclopentane with ethylene in the presence of catalytic amounts of Cp2- ZrCI 2 leading to the formation of 2-phenylmagnesium-cyclopentane and 2,4-di- phenylmagnesium-cycloheptane, were studied for the first time. It was found that zirconocyclopentanes, are intermediates in this reaction, which are formed both from magnesium-cycloaikanes and from ~-olefins and Cp2ZrCI 2. A possible mechanism of the reactions studied has been proposed.

We have recently [i] carried out a catalytic cyclometallation of olefins by means of n-Pr2Mg in the presence of Cp2ZrCI 2, whereby substituted magnesium-cyclopentanes were ob- tained. Zirconocyclopentanes (ZCP) may possibly be catalytically active intermediates in the cyclometallation.

This reaction occurs most readily when styrene is used as the olefin (overall yield of magnesium-cyclopentanes 2 95%).

According to [2, 3], 1,4-tetramethylene-bis(cyclopentadienyl)zirconium (I) and its de- rivatives undergo transformations with splitting of the metallocyclopentane ring, preferen- tially into ethylene or l-butene, depending on conditions:

Cdl,-6Cp~Zr ~----Zr ~ ~ ~ ~ Cp2Zr-t-C4H~ . ~ ,/ \ /

/ / "" \ Z r Zr Cp C l, / \ / / \ Up Cp Up Cp

(1)

In the present work, we studied the reaction of a unsubstituted magnesium-cyclopentane (II) with styrene by the action of catalytic amounts of Cp2ZrCI 2 in a THF solution in order to develop a new variant of the synthesis of (II), to experimentally confirm the formation of ZCP by intramolecular cyclometallation of olefins, and also to clarify the mechanism of the transmetallation of ZCP in the presence of R=Mg into (II).

The reaction of styrene with (II) taken in a i:i ratio in the presence of 2-3 mole % of Cp2ZrCI 2 in a THF solution at 25~ (1.5 h) results in the formation of a mixture of or- ganometallic compounds in an overall yield of -75%, based on styrene used. At the same time, -95% of ethylene was evolved in the course of the reaction, based on the starting (II). As a result of decomposition of the reaction products by the action of HCI and DCI, butyl- benzene (III) (-95%) and 1,3-diphenylhexane (IV) (-5%) or 1,4-dideutero-l-phenylbutane (V) (-95%) and 1,6-dideutero-l,3-diphenylhexane (VI) (-5%), respectively, are formed in each experiment.

The structure of the separated hydrocarbons (III)-(VI) indicates the formation in this reaction of organomagnesium compounds, in which the magnesium atom is bound simultaneously to C I and C4 or C l and C 6 carbon atoms in the hydrocarbon chain, which corresponds to the

Institute of Chemistry, Bashkir Scientific Center, Ural' Branch, Academy of Sciences of the USSR, Ufa. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimi- cheskaya, No. 6, pp. 1388-1393, June, 1991., Original article submitted April 27, 1990.

0568-5230/91/4006-1229512.50 �9 1991 Plenum Publishing Corporation 1229

formation in the course of cyclometaliation and transmetallation of molecules of 2-phenyl- magnesium-cyclopentane (VII), and an insignificant amount of 2,4-diphenylmagnesium-cyclohep- tane (VIII).

It =~- 11(111), (IVy, D(V),(Vll.

/ - - ~ / + p h / % Mg , ( 11 ) cl~.,zrcI,

-r P h

J

+ ( ' ) , l~l~ P}t

(VI I ) (V I I I )

! j llc',l

v v ~

\ ~ lq~ - / / \ / p } ~ _ l ~ l / " \ , / - ! t Si Ph Ii it J>h / / \x

(IX) (lli) (IV) (V) (Vl)

To obtain a more reliable confirmation of the structure of (VII), it was treated by Me2SiCI 2 to yield l,l-dimethyl-2-phenylsilacyclopentane (IX) in 80% yield.

Thus, the magnesium-cycloalkanes (VII) and (VIII) synthesized by us are constructed from one molecule of ethylene and styrene in the case of (VII) and from two molecules of styrene and a molecule of ethylene for (VIII).

For an experimental verification of the proposed mechanism and to carry out a counter- synthesis of (VII), (VIII) under the selected conditions, we carried out the reaction of 2,4- diphenylmagnesium-cyclopentane (X) obtained according to [i], with ethylene, catalyzed by Cp2ZrCI2. Thus, styrene and a mixture of (VII) and (VIII) were obtained in a ratio of 65:13: 22, respectively, in a 75% yield. These results completely confirm our expectation of the participation of zirconocycloalkanes as new key intermediates in the formation of magnesium- cycloalkanes.

/" Cpo ZrCl 2 ' 3 mole % /~\ / ( ~ \ . + Ctlo..:CII., ~ ' Ph . " " THF-ether ( i : 1 )

]qi M~ 4 h, 75% (x)

+ ( v I I ) + ( v i i i )

The experiments that were carried out made it possible to propose a complete scheme of transformations of ethylene, styrene, (II) and (X) by the action of catalytic amounts of Cp2- ZrCI 2. According to the scheme, at the first stage, from Cp2ZrCI 2 and (II), 1,4-tetramethyl- ene-bis(cyclopentadienyl)zirconium (I) is formed by transmetallation, which is split under the reactions conditions and converted into a bisethylene complex (XI). Because of the con- siderable excess of styrene in the reaction mixture, ethylene is displaced from the coordi- nation sphere of (XI) and ~-complexes (XII), (XIII) are formed. An intramolecUlar cyclo- metallation occurring in complexes (XII) and (XIII) leads to zirconocyclopentanes (XIV), (XV). Inclusion of an ethylene molecule at the Zr-C bond in complex (XV) proceeds with the formation of 2,4-diphenyl-l,6-hexamethylene-bis(cyclopentadienyl)zirconium (XVI). In the reaction of (XIV), (XVI), and (II), the corresponding magnesium-eycloalkanes (VII), (VIII) are formed and the starting active intermediate (I) is regenerated (see scheme on page 1233).

EXPERIMENTAL

Magnesium-cyclopentane (II) was synthesized according to a method described in [4]. The reactions were carried out in a dry argon atmosphere. The IR spectra were run on a UR-20 spectrophotometer (thin layer). The IH NMR spectra were recorded on "Tesla BS 487" (i00 MHz) and "Tesla BS ~67" (60 MHz) spectrometers, Using TMS as internal standard and CDCI~ as the solvent. The 13C NMR spectra were recorded on "JEOL FX 90Q" (22.5 MHz) and "Bruker MM-300"

1230

TABLE

I.

13C NMR

Spectra

of

Compounds

(III),

(IV),

(V),

(Vl),

(IX)

6,

ppm,

CDCI 3,

TMS)

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mp

ou

nd

<

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: t:"

C

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2 4

q/. -

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V)

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==

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t J=

12

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%' 1

Hz

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cis

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to

TABLE i

(continued)

Colllp0und

(:

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)

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125,

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I25,

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128,

30

128,

25

d

or

-,

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d

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s

115,

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S

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I ',2J;()

s 1,79

q

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trans

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,)

,)9

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128.

25

d

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8f;

d d

Ph

?ph CpzZrCL z

t (zT) Mgs z

11,,.% J/b/\op Cx/) //I Pk / \ H ~

2 (xy) ph.%? b

[p\Cp ph / / 1 / . , , . . _$/-. -\\ (X~)

[p / \

// p h"~ [p s

/ / \

s Cp

spectrometers. The mass spectra were obtained on an "MX-1320" mass spectrometer at the ion- ization chamber temperature of 150~ and ionizing voltage of 12 and 70 eV. The GLC analysis was carried out on a "Chrom-5" chromatograph with a flame ionization detector, SE-30 (5%) and PEG-6000 (15%) on Chromaton N-AW-DMCS (0.16-0.20m m), using 3.7 and2.4-m columns at 50-300 and 50-170~ respectively, carrier gas - helium. In the analysis of (X), a katharometer was used, with SKTFT on a Inertone-super as the stationary phase, a 2.4-m column, 50-300~ The analysis of the chromatograms was carried out using an internal standard (decane, tol- uene).

Reaction of (II) with Styrene. A 30-mmole portion of (II) in THF (0.52 mmole/ml), 3.12 g (30 mmoies) of styrene, and 0.175 g (0.6 mmoles) of Cp2ZrCI 2 were charged in an Ar atmos- phere into a 100-ml glass reactor mounted on a magnetic stirrer. The solution formed was stirred for 1.5 h at 20-25~ and then was cooled to 0~ hydrolyzed with 5% HCI, and ex- tracted with ether (3 • 50 ml). The extract was dried over MgSO~, the solvents were evapor- nted, and the residue was analyzed by GLC. By distillation in vacuo, 2.97 g (75%) of butyl- ~enzene (III) and 0.22 g (6%) of 1,3-diphenylhexane (IV) were isolated from the reaction mix- :ure.

In the reaction of 30 mmoles of (II) and 30 mmoles of stryene by the above-described method, followed by deuterolysis of the reaction mixture, 2.9 g (70%) of 1,4-dideutero-1- butylbenzene (V) and 0.25 g (7%) of 1,6-dideutero-l,3-diphenylhexane (VI) were isolated.

The synthesis of (IX) was carried out by the method in [5]. Yield, 3.2 g (80%) of l,l- dimethyl-2-phenylsilacyclopentane~

The reaction of (X) with ethylene was carried out in an autoclave at 25~ Ratio (X): ethylene = I:I and 1:2. The pressure of ethylene was 12.5 and 25 atm.

The purity of the products obtained was not less than 96%.

Butyibenzene (III), mp 62~ (i0 mm), nD 2~ 1.4897. IR spectrum (v, cm-l): 690 (C=C arom.); 715 (C-H arom.); 1040, 1070 (C-H); 1460 (CH2, CHa) ; 1500, 1600 (C--C arom.); 1800, 1870, 1940 (C-C arom.); 3030, 3060 (C-H arom.). PMR spectrum (6, ppm): 0.9 t (3H, CHa, J = 7.5 Hz), 1.35-1.7 m (4H, 2CH2), 2.6 t (2H, CH2-Ph , J = 7.5 Hz), 7.15-7.35 m (SH, Ph). M + 134.

1,3-Diphenylhexane (IV), bp 197~ (17 mm), nD 2~ 1.5331. IR spectrum (v, cm-l): 690 (C arom.=C); 715 C--Harom.); 1040 (C-H arom.); 1460 (C-H, CH2CHs) ; 1500, 1600 (C=C atom); 1800, 1870, 1940 (C--C atom.); 3030, 3060(C--Harom.). PMR spectrum (6, ppm): 0.82 t (3H, CH 3, J = 7.0 Hz), 1.1-1.8 m (6H, 3CH2) , 2.25-2.75 m (3H CH, CH~-Ph), 7.1-7.4 m (10H, 2Ph). Calculated, %: C 90.76; H 9.24. Found, %: C 90.68; H $.21. M ~ 238.

l~4-Dideutero-l-butylbenzene (V), bp 82~ (17 mm), nD 2~ 1.4902. IR spectrum (v, cm-l): 690, 730, 1450, 1500, 1600, 1800, 1860, 1940, 2170 (C-D); 3025, 3070~ PMR spectrum (~, ppm): 0.92 t (2H, CH2D, J = 7.5 Hz), 1.35-1.7 m (4H, 2CH2) , 2.58 t (IH, CH-D, J = 7.5 Hz), 7o15-7o3 m (5H, Ph)o Calculated: C 88.24~ H 11o78%o Found~ C 88o25~ R 11.69%. M + 136.

1233

1,6-Dideutero-l,3-diphenylhexane (VI). bp 137~ (2-3 mm), nD 2~ 1.5359. IR spectrum (v, cm-1): 690, 730, I~50, 1500, 1600; 1800, 1870, 1940, 2175 (C-D), 3030, 3060. PM_R spec- trum (5, ppm): 0.81 t (2H, CH2D, J = 7 Hz), 1.1-1.7 m (6H, 3CH2), 2.20-2.70 m (2H, CH, CHD- Ph), 7.1-7.4 m (10H, 2Ph). Calculated: C 90.0; H 10.0%. Found: C 90.0; H 10.03%. M + 240.

l~l-Dimethyl-2-phenylsilacyclopentane (IX), bp 55-56~ (3 mm), nD 2~ 1.5096. IR spec- trum (v, cm-1): 715 (C-H arom.); 800 (Si CH3); 850, 860 (Si(CH3)2) ; 1210, 1250 (Si-Ch2) ; 1260 (Si-CH3); 1415 (Si-CH2); 1500, 1600, 1735, 1790, 1860, 1925, 3030, 3070, 3090. PMR spectrum (6, ppm): -0.175 s (3H, CH~-Si), 0.25 s (3H, CH3-Si), 0.92 t (2H, CH2-Si , J = 7.5 Hz), 1.25-2.00 m (4H, 2CH2), 2.25 t (IH, CH, J = 7.5 Hz), 7.1-7.5 m (5H, Ph). Calculated, %: C 75.79; H 9.47; Si 14.74. Found, %: C 75.4; H 9.44; Si 14.69. M + 190. The I~C NMR spectra are given in Table i.

I.

2. 3.

4.

5.

LITERATURE CITED

R. M. Sultanov, R. G. Gaimaldinov, and R. R. Muslukhov, Summaries of Lectures at the All-Union Conference on the Use of Metallocomplex Catalysis in Organic Synthesis [in Russian], Ufa (1989), p. 40. S. Datta, M. B. Fischer, and S. S. Wreford, J. Organomet. Chem., 188, 352 (1980). J. X. McDermott, M. E. Wilson, and G. M. Whitesides, J. Am. Chem. Soc., 98, 6529 (1976). H. C. Holtkamp, G. Schat, C. Blomberg, and F. Bickelhaugt, J. Organomet. Chem., 24_._9_0, No. i, i (1989). H. Xiong and R. D. Rieke, J. Org. Chem., 54, No. 14, 3247 (1989

SYNTHESIS OF I-TERT-BUTYL-2-ARYLDIAZENE-2-OXIDES

BY REACTIONS OF t-BuNHMgBr WITH NITROBENZENES

E. T. Apasov, B. A. Dzhetigenov, Yu. A. Strelenko, A. V. Kalinin, and V. A. Tartakovskii

UDC 542.91:542.952.1:547.566.2: 547.546:547.233+546.46'141

A new method has been developed for the synthesis of alkylaryldiazene oxides by the reactions of t-BuNHMgBr with nitrobenzenes. The cis-azoxy compound l-tert-butyl-2-(2-chlorophenyl)diazene-2-oxide, which irreversibly isomerizes to the trans isomer upon heating, was obtained for the first time under chem- ical reaction conditions.

Alkylaromatic diazene oxides are usually obtained by the reactions of aromatic nitroso compounds with dihaloamines [1-3]. Synthesis of asyn~metric diaryldiazene oxides from aro- matic nitro compounds under the effect of ArN(MgBr) 2 was described earlier [4, 5].

We have shown that aromatic nitro compounds (I) react with t-BuNHMgBr (II) fairly smooth- ly to give a corresponding alkylaryldiazene oxides (III)

1- t -BuNH,MgBr ( I I ) 2. II:.Oq- N H4CI

ArNO~ * t-BuN=N(O)Ar -% t-BuN=NAt (i) ( i l i ) (iv)

At' = Ph (a), 2-M%SiNI1C~II4 (b~ ,* 4-C1C~tt 4 (c), 2-C1C6II4 (d).

Condensation occurs slowly at ~20~ and accelerates upon heating practically without a change of the product ratio (Table I). Characteristics of the products are given in Tables 2-4.

*In (IIlb) and (IVb) Ar = 2-NH2CsH~, the loss of the Me3Si group evidently occurs in step 2.

N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1394-1397, June, 1991. Original article submitted September 14, 1990.

1234 0568-5230/91/4006-1234512.50 �9 1991 Plenum Publishing Corporation