J . Org. Chem., Vol. 40, No.21, 1975 3097
Synthesis of Mono- and Bis(trimethylsily1)anthracenes bond exchanges the pro-€ methyl in 4a(l) with the pro-2 methyl In 4a(2).the later must give rise to the doublet at 6 1.30. (1 1) D. Kost, E. H. Carlson, and M. Raban, Chem. Commun., 656 (1971). 1 (1967). (12) K. Mislow and M. Raban. Top. Stereochem.. I, (13) (a) G. G. Overberger, N. P. Marullo, and R. G. Hiskey, J. Am. Chem.
Soc., 83, 1374 (1961); (b) T. YoshiQ and K. Harada, Bull. Chem. SOC. Jpn., 45, 3706 (1972). (14) D. Kost, unpublished results. (15) (a)J. v. Braun, E. Anton. and K. Weissbach, Ber., 63, 2847 (1930): (b) W. Reeves and I. Christoffel,J. Am. Chem. SOC.,72, 1480 (1950).
Synthesis of Mono- and Bis(trimethylsily1)anthracenes Hee Cho and Ronald G. Harvey* Ben May Laboratory, T h e University of Chicago, Chicago, Illinois 60637 Received M a y 16,1975 Synthesis of the previously unknown 1-, 2-, and 9-trimethylsilylanthracenesand of the 9,lO- and 1,3-bis(trimethylsily1)anthracenes has been accomplished. Aromatization of 9-trimethylsilyl-9,lO-dihydroanthracenevia the dianonic intermediate generated with the n-butyllithium-TMEDA reagent and cadmium chloride afforded 9-trimethylsilylanthracene in overall yield exceeding 90%. Reaction of trimethylsilyl chloride with the anthraand transcene-lithium-TMEDA complex gave cis- and trans-9,10-bis(trimethylsilyl)-9,1O-dihydroanthracene 1,2-bis(trimethylsilyl)-1,2dihydroanthracene. Aromatization of the trans-9,10 isomer afforded 9,lO-bidtrimethylsilyl)anthracene, while similar reaction of the trans-1,2 isomer led to 1- and 2-trimethylsilylanthraceneand 1,3bis(trimethy1silyl)anthracene. Details of the mechanisms of these reactions and the 270-MHz NMR spectra are discussed.
Synthesis of the isomeric trialkylsilylanthracenes has not previously been achieved. Reaction of 9-bromoanthracene with Mg and Me3SiCl reportedly afforded only the parent hydrocarbon.' In our experience, cross metalation of 9-bromoanthracene with n-butyllithium, followed by MesSiCl, failed to furnish 9-trimethylsilylanthracene (2), although analogous reaction of 9-bromophenanthrene gave 9-trimethylsilylphananthrene in good yield (95%).* Synthesis of 2 has now been accomplished through reacat tion of Me3SiCl with 9-lithio-9,lO-dihydr~anthracene~ -78' followed by aromatization with n-butyllithiumTMEDA and cadmium(I1) ~ h l o r i d eThe . ~ overall yield ex-
H
Reaction of 1 with n-butyllithium (10% excess) in tetrahydrofuran at Oo afforded a deep red solution of the monoanion which failed to undergo trimethylsilylation with Me3SiC1. Similar reaction employing a large excess (200%) of the lithium reagent also failed, as might have been anticipated from the known resistance to formation of the anthracene dianion via deprotonation in ethereal solvent^.^
* SiR3
SiR,,
SiR,
\ /
3
BR,l
R = CH,$
I
1
2
ceeded 90%. The intermediacy of the dianion of 9-trimethylsilylanthracene was evidenced by the success of the second step and by the characteristic purple color of the solution before the addition of the cadmium salt. The ability of the trimethylsilyl group to stabilize the adjacent negative charge contrasts with the contrary effect of the tert-butyl group in this regard; similar reaction of 9-tert- butyl-9,lOdihydroanthracene was found earlier to afford a dimeric product arising from the lO-m~noanion.~ Attempted aromatization of 9-trimethylsilyl-9,lO-dihydroanthracene(1) with trityl trifluoracetate in trifluoroacetic acid: a reagent found to be effective in dehydrogenation of many hydroaromatic compounds, furnished anthracene as the sole product. Undoubtedly, this is a consequence of the facility of acidic cleavage (protodesilylation) of aryl silanes.2 Attempted synthesis of 9,10-bis(trimethylsilyl)anthracene (3) through repetition of the sequence of trimethylsilylation and aromatization on 1 was not successful owing to preferential formation of the monoanion a t the 9 position.
However, reaction of MesSiCl with the anthracene dianion in the form of its lithium N,N,N',N'-tetramethylethylenediamine complex generated by the method described4 gave a mixture of cis- and trans-9,10-bis(trimethylsilyl)9,10-dihydroanthracene (cis- and trans-4) and 1,2-bis(trimethylsilyl)-1,2-dihydroanthracene(5) in a molar ratio of .[TMEDA.I,if]i
R,SiCI
H
H
H" 'SiR,!
5
RSi
cis4
-
SiR
trans-4
10:5:4 by NMR analysis. Similar reaction with the addition of MesSiCl carried out a t Oo afforded a cleaner product with cis- and trans-4 and 5 in the molar ratio 101:5. Chromatography on basic alumina and recrystallization furnished the pure compounds as crystalline solids melting a t
3098
J. Org. Chem., Vol. 40, N o . 21, 1975
67-68, 172, and 126", respectively. The cis isomer was found to be somewhat unstable, exhibiting a tendency toward decomposition during chromatography or purification by other means. A minor additional product (-3%), mp 138-139", was also isolated. It was identified as a dimer of 2 on the basis of microanalysis and the NMR spectrum which exhibited methyl, benzylic, and aromatic protons in the ratio 18:2:16. The methyl and benzylic signals appeared as singlets at 6 -0.11 and 4.01, respectively, while the aromatic protons furnished two multiplets with the downfield multiplet (6 8.09-8.50) equivalent to four protons, which are presumably those flanking the Me3Si group (HI,J.,~,~/). The faceto-face (6a) and tail-to-tail (6b) structures are most consistent with this data and cannot a t present be distinguished. R3Si
I
H
Cho and Harvey whereas Hg of 7 appeared a t lower field (6 8.53) than Hlo (6 8.30), indicating the presence of the bulky trimethylsilyl group in the adjacent 1 position. Other features of both spectra were also consistent with these assignments. SiR3
I
7
$iR3
Finally, trans- 4 underwent smooth epimerization to cis- 4 on treatment with the alkyllithium reagent quenching
I
reaction with water rather than CdC12. This stereochemical result is similar to that observed previously with the analogous 9,10-dialkyl-9,10-dihydroanthracenes.3
H
SiRB 6a
6b
The integrated NMR spectra of 4 and 5 were consistent with their structural assignments. The cis and trans stereoisomers of 4 were assigned on the basis of the relative chemical shifts of the benzylic protons (6 3.83 and 3.66, respectively) in comparison with those of the analogous cisand trans-9,lO-bis-tert-butylcompounds (6 3.97 and 3.83, re~pectively).~ The structure of the 1,2-bis(trimethylsilyl) compound 5 was distinguished from alternative structures, such as the 1,4 isomer, by the 270-MHz NMR spectrum, which displayed singlets at high field 6 -0.09 and -0.02 for the trimethylsilyl protons. The allylic and benzylic protons appeared as a doublet a t 6 1.96 ( J 2 , 3 = 7 Hz) and a broad singlet at 6 2.45, respectively, while the vinyl region showed an AB pattern with doublets a t 6 5.90 and 6.31 (J3,4 = 10 Hz) with additional coupling ( J 2 , 3 = 7 Hz) of the H3 proton to the allylic hydrogen. Tentatively, the trimethylsilyl groups are assigned as trans with the bulky groups in the axial orientation, known to be preferred by related dihydroaromatic ring s y ~ t e m s ;coupling ~.~ between the benzylic and allylic protons was not detected, consistent with the normally small couplings exhibited by diequatorial protons in these ring systems. Dehydrogenation of 4 with n-butyllithium-TMEDA and cadmium(I1) chloride4 furnished the previously unknown 9,10-bis(trimethylsilyl)anthracene(3) isolated as a crystalline solid, mp 112-113", and 2 in a molar ratio of 58.5. Dehydrogenation of the trans-1,2-bis(trimethylsilyl) compound 5 with alkyllithium-TMEDA reagent failed to afford 1,2-bis(trimethylsilyl)anthracene as anticipated, but instead furnished the previously unknown 1- and 2-trimethylsilylanthracene (7 and 8) plus a disilyl derivative of anthracene. The latter on the basis of the NMR spectral data appears to be not the anticipated 1,2 isomer, but rather 1,3-bis(trimethylsilyl)anthracene (9). The NMR spectrum of the latter compound exhibited characteristic singlet peaks a t 6 7.73 and 8.12 in the aromatic region assigned to H2 and H4, respectively; other features of the spectrum were entirely consistent with this assignment. Conversely, the spectrum lacked the characteristic AB quartet pattern anticipated for the Ha, H4 protons of the 1,2 isomer. Therefore, the latter structure may be rejected. The 1 and 2 isomers, 7 and 8, were also readily distinguished through their NMR spectra. The 9,lO protons of 8 appeared as a broad singlet a t 6 8.30 in the region expected for anthracene itself,
Discussion The foregoing syntheses of the mono- and bis(trimethylsily1)anthracenes provide convenient synthetic access to this class of compounds. It is likely that this synthetic approach will prove applicable to the preparation of other aryl silanes. The origin of the 1,2-bis(trimethylsilyl) isomer, 5 , though not immediately obvious, is explicable as a consequence of the structure of the anthracene-lithium-TMEDA complex.8 According to X-ray crystallographic analysis, the anthracene dianion is somewhat puckered with a lithium ion centered above the face of the central ring and the second lithium ion situated on the opposite face of the polycyclic ring system and centered over one of the outer rings. Although maximum charge density is expected at the 9,10 positions, significant negative charge is localized in one of the outer rings, facilitating electrophilic attack of the relatively bulky trimethylsilyl reagent a t least partially in this region. While the stereochemistry of 5 could not be assigned with certainty, it is most probably trans. In the trans isomer the bulky MesSi groups would be expected to occupy the diaxial positions, and the resulting diequatorial 1,2 protons would be expected to show a coupling constant (Jcalcd = 4.1 H Z ) somewhat ~ smaller than the equivalent protons of the cis isomer (Jcalcd = 5.2 Hz) due to the smaller dihedral angle. However, no coupling could be detected in the highresolution NMR spectrum of 5, and the stereochemistry remains uncertain. The observed cis stereochemical preference in the trimethylsilylation of anthracene is unexpected in view of the recent evidence that the stereochemistry of alkylation of the alkylanthracenyl anion is predominantly sterically controlled with larger groups leading to tran~alkylation.~ Also, Russian workers have reportedlo that interaction of anthracene with lithium metal in ether (70 hr), followed by reaction with MesSiCl, furnished a major product of unspecified stereochemistry melting a t 168-170", which is presumably trans-4 (mp 172"). Thus, the present result appears anomalous. One explanation is that trans-? is indeed the initial product which is transformed to cis-4 via subsequent epimerization. This is consistent with previous finding$ with the 9,10-dialkyl-9,10-dihydroanthracenes. Also, trans- 4 on treatment with the alkyllithium-TMEDA reagent in refluxing cyclohexane was found to undergo smooth transformation to cis- 4. While this explanation appears attractive, it is inconsistent with the observation of a decreased proportion of trans-4 a t lower temperature (0"),
Synthesis of Mono- and Bis(trimethylsily1)anthracenes a condition less favorable for epimerization. Therefore, further investigation will be required to solve this problem, which is outside the scope of the present study. Dehydrogenation of the trans- 1,2-bis(trimethylsilyl) compound 5 followed an unexpected course. In place of the anticipated 1,2-bis(trimethylsilyl)anthracenewere found 1and 2-trimethylsilylanthracene (7 and 8) plus 1,3-bis(trimethylsily1)anthracene (9). From a purely synthetic viewpoint this is fortunate, since it provides convenient synthetic access to the remaining two monotrimethylsilyl isomers of anthracene. The origin of 7 and 8 is explicable in terms of basic elimination of trimethylsilane from 5 via an intermediate such as 10. Formation of 9 is less obvious. The possible pathways include (1)nucleophilic attack of the trimethylsilyl anion on 7 or 8 to produce an intermediate such as 11 followed by hydride loss, or (2) direct formation of 11 from 10 through migration of a trimethylsilyl group followed by similar hydride 1oss.l’ No attempt was made to distinguish between these two pathways. H
SiR,
J . Org. Chem., Vol. 40, No. 21, 1975 3099 tening due to transannular interaction was detected, and the 9,10-bis(tert- butyl) derivatives exhibited only a single peak in the benzylic region for both isomers. It appears, therefore, that cis- and trans-4, owing to the large steric demands of the trimethylsilyl groups, similarly exist in “flattened” conformations with the trans isomers closely approaching planarity. Introduction of the trimethylsilyl group into anthracene markedly affected the chemical shifts in the NMR spectrum of the nearby aromatic protons. Substitution of this group into the 1 position, as in 7 and 9, caused a shift of Hg 0.23 ppm downfield, while substitution in the 9 position led to a shift of Hlo in the same ring upfield from 6 8.30 to 8.14. Evidently, both through-space and inductive effects are important. It is interesting that similar effects are found in the analogous tert-butyl derivatives of anthracene. The H2 proton of 1-tert-butylanthracene appears downfield 0.58 ppm from the meso protons of anthracene, while the Hlo proton of 9-tert-butylanthracene exhibited an upfield shift from 6 8.30 to 8.22.13 Experimental Section
8
10
H’
’SiR3
&iR3
11
9
Formation of the monoanion a t the 9 position of 1 on treatment of the latter with butyllithium is deserving of comment. That a monoanion is indeed present is confirmed by the characteristic deep red color of the solution which is quite different from the intensely purple color of the anunder thracene d i a n i ~ n .9-Alkyl-9,lO-dihydroanthracene ~,~ similar conditions affords the 10 monoanion, which undergoes facile a l k y l a t i ~ n .Since ~ trimethylsilylation was not observed, the monoanion of 1 must bear the charge in the relatively inaccessible 9 position. Stabilization of a negative charge by the trimethylsilyl group is consistent with previous observations of the directive effect of this group in the Birch reduction of si1ylnaphthalenes.l2 The NMR data on more careful inspection reveal several interesting facts concerning the structures of the silylated derivatives of anthracene. Thus, the cis- and trans-9,lObis(trimethylsily1) isomers, cis- and trans-4, exhibit only one singlet peak for the benzylic protons of each isomer. In earlier studies3r7 NMR analysis of the closely related 9alkyl- and 9,10-dialkyl-9,10-dihydroanthracenesdemonstrated existence of this ring system in a nonplanar boat structure with the alkyl groups preferentially occupying the pseudo-axial positions. Thus the cis isomers exist principally as the diaxial conformer, while the trans isomers exhibit strong preference for the conformer bearing the bulkier group in the axial position. With large groups, ring flat-
cis
H
H
H
R trans
Materials a n d Methods. NMR spectra were recorded on a Varian T-60 or Bruker 270-MHz spectrometer; CC14 was employed as the solvent and Me& as internal standard for the 270-MHz spectra and cyclohexane (s at 6 1.43 relative to the Me&) as internal standard for the 60-MHz spectra. Ether, cyclohexane, N,N,N‘,Ntetramethylethylenediamine (TMEDA), and tetrahydrofuran (THF) were purified by distillation from LiAlH4. n-Butyllithium (15% in hexane) was obtained from Apache Chemicals. Cadmium chloride was dried in vacuo a t 100’ overnight and stored in airtight vials. Trimethylsilyl chloride (Alfa Ventron) was redistilled before use. Microanalyses for C and H correct to f0.3% were obtained for all new compounds from Atlantic Microlabs, Inc. 9-Trimethylsilyl-9,lO-dihydroanthracene(1). The procedure employed was essentially that found most effective for the monoalkylation of 9,lO-dihydroanthra~ene.~~~ To a stirred solution of 9,lO-dihydroanthracene (7.2 g, 40 mmol) in T H F (200 ml) a t -33’ under nitrogen was added a solution of n-butyllithium in hexane (44 mmol). The resulting brownish-red solution was stirred for 30 min, then the temperature was lowered to -78O, and stirring was continued for an additional 30 min. Upon addition of MesSiCl (6 ml) the solution became pale yellow. Addition of water and ether followed by conventional work-up afforded a pale yellow solid product, chromatography of which on Florisil (30 g) eluted with hexane (600 ml) gave pure 1 (9.8 g, 97%). Recrystallization from petroleum ether gave 1 as white crystals (9.2 g): mp 116O (lit.6 mp 112-113’); NMR 6 0.05 (s, 9, CHs), 3.61 (s, 1, Hg), 3.96 (apparent s, 2, H d , and 7.13 ppm (apparent s, 8, aromatic). 9-Trimethylsilylanthracene(2). To a solution of 1 (2.52 g, 10 mmol) in cyclohexane (60 ml) and TMEDA (30 ml) was added a solution of n-butyllithium (40 mmol) in hexane. The resulting purple solution was heated a t reflux for l hr, then allowed to cool for 5 min and the color discharged by addition of CdClz (3.7 g, 20 mmol). Addition of water and ether followed by conventional work-up gave a brown oil. Chromatography of the latter on Florisil (20 g) eluted with petroleum ether (500 ml) gave 2 (2.4 g, 95%) as a pale yellow oil. Crystallization from petroleum ether furnished crystalline 2 (2.2 9): mp 60-61’; NMR 6 0.63 (s, 9, CH.?),7.03-7.43 (m, 4, aromatic, H2,3,6,7), 7.57-7.83 (m, 2, aromatic, H4.51, 8.14 (s, 1, Hlo), and 8.10-8.47 ppm (m, 2, aromatic, H1.8). Reaction of Trimethylsilyl Chloride with t h e LithiumTMEDA Complex of t h e Anthracene Dianion. To a solution of 9,lO-dihydroanthracene (3.6 g, 20 mmol) in cyclohexane (120 ml) and TMEDA (60 ml) was added n-butyllithium (80 mmol) in hexane. The resulting purple solution was refluxed for 1 hr under nitrogen and allowed to cool for 5 min; then Me:$iCl (12 ml) was added. The resulting exothermic reaction subsided in 5 min. Stirring was continued for 30 min more, then the reaction mixture was worked up by a conventional extraction procedure with ether. Rapid chromatography through a column of Florisil (20 g) eluted with petroleum ether (500 ml) gave a partially crystalline pale yellow oil (6 g), NMR analysis showed cis- and trans-4 and 5 in a molar ratio of 105:4. The cis isomer was found to be somewhat unstable, necessitating appropriate care to minimize loss through decomposition during chromatography or purification by other
3100 J . Org. Chem., Vol. 40, No. 21, 1975 means. Crystallization of the product mixture from petroleum ether gave colorless crystals of trans-4 (0.85 9). The second crop (0.55 g) contained in addition to trans-4 yellow crystals of a minor additional component which was readily separated mechanically or by dissolving the trans-4 in petroleum ether. This new compound on recrystallization from ether-petroleum ether gave needles: mp 138-139’; NMR 6 -0.11 (s, 9, CH3), 4.01 (s, 1,benzylic), 6.07-7.56 (m, 6, aromatic), and 8.09-8.30 ppm (m, 2, aromatic). The dimeric structure 6 was tentatively assigned. Recrystallization of the combined trans-4 from petroleum ether gave pure trans-4 (1 9): mp 172’; NMR 6 -0.15 ( 8 , 18, CH3), 3.66 (s, 2, benzylic), and 6.89 ppm (s, 8, aromatic). Chromatography of the remainder of the product (4.5 g) on basic alumina (180 g) gave in order of elution with petroleum ether 5 (700 mg), a 1:l mixture of trans-4 and 5 (550 mg), and trans-4 (350 mg). Further elution with 10% benzene in petroleum ether gave cis-4 (900 mg), and final elution with benzene furnished anthracene and a trace of cis-4 (600 mg). Rechromatography of the cis-4 on basic alumina (30 g) gave pure cis-4 (800 mg): mp 67-68; NMR 6 0.02 ( 8 , 18, CH3), 3.83 (9, 2, benzylic), and 6.92 ppm (s,8, aromatic). Recrystallization of the fractions containing 5 from petroleum ether gave a total of 850 mg of pure 5: mp 126O; NMR 6 -0.09 (s,9, CH3), -0.02 ( s , 9, CH3), 1.96 (d, 1,J2,3 = 7 Hz, Hz), 2.45 ( s , 1,Hi), 5.90 (d of d, l,J3,4 = 10,J2,3 = 7 Hz, H3), 6.31 (d, l , J 3 , 4 = 10 Hz, H4), 7.09 (s, 1, Hg or Hlo), 7.15 (s, 1, Hg or Hm), 7.17-7.25 (m, 2, H6,7), and 7.33-7.58 ppm (m, 2, H5,s). Similar reaction with the trimethylsilylation carried out at lower temperature ( O O ) gave a cleaner product shown by NMR analysis to contain cis- and trans-4 and 5 in the molar ratio 10:1:5, the most striking difference being the depressed yield of the trans isomer. 9,10-Bis(trimethylsilyl)anthracene(3). To a solution of trans-4 (325 mg, 1 mmol) in cyclohexane (12 ml) and TMEDA (6 ml) was added a solution of n-butyllithium (8 mmol) in hexane. The resulting solution was heated a t reflux for 2 hr; the purple color of the dianion developed after the first hour. The solution was allowed to cool for 5 min, then the color was discharged by addition of CdClz (0.74 g, 4 mmol). The mixture was stirred for another 30 min while metallic cadmium was precipitating. Water was added and the mixture was extracted with ether and worked up by conventional procedure to furnish a brown oil (280 mg). Chromatography on neutral alumina (50 g) eluted with petroleum ether gave 3 (110 mg) and 2 (140 mg). Recrystallization of the former from petroleum ether gave pure 3 as greenish-yellow needles: mp 112-113O; NMR 6 0.67 (s, 18, CH3), 7.23-7.43 (m, 4, H2,3,6,7), and 8.22-8.42 ppm (m, 4, H1,4,5,8).Recrystallization of the latter from the same solvent gave pure 2 as yellow crystals, mp 61’. The product mixture from a similar reaction on heating in a solution of 10% concentrated HCl in refluxing acetic acid for 2 hr underwent protodesilylation to furnish anthracene almost quantitatively. E p i m e r i z a t i o n of trans- t o cis-4. Treatment of trans-4 with n-butyllithium and TMEDA according to the procedure employed for synthesis of 2 from 1 except that CdClz was not employed afforded pure cis-4 free of trans-4 (95% yield). D e h y d r o g e n a t i o n of trans-1,2-Bis(trimethylsilyl)-1,2-dihyd r o a n t h r a c e n e (5). Dehydrogenation of 5 (324 mg, 1 mmol) with the n-butyllithium-TMEDA reagent according to the general procedure4 which was employed for synthesis of 2 gave a pale yellow
Cho a n d Harvey oil (320 mg). Chromatography on Florisil (5 g) eluted with petroleum ether (200 ml) gave a colorless oil (250 mg) shown by NMR analysis to contain 1- and 2-trimethylanthracene (7 and 8) and 1,3-bis(trimethylsilyl)anthracene (9) in the molar ratio 4:1:2. A second chromatography on Florisil(50 g) eluted with the same solvent afforded initially 9 (80 mg) followed by the mixture of 7 and 8 (150 mg) which proved difficult to separate. However, pure samples of each were obtained by rechromatography of the early fractions rich in 7 on neutral alumina and of the later fraction rich in 8 on basic alumina. Compound 7 was obtained as a colorless oil: NMR 6 0.53 (6, 9, CH3), 7.15-7.67 (m, 4, H2,3,6,7), 7.73-8.10 (m, 3, H4,5,8), 8.30 (s, 1, Hlo), and 8.53 ppm (s, 1, Hg). Compound 8 was a solid which was recrystallized twice from petroleum ether to afford colorless plates: mp 161-161.5’; NMR 6 0.36 (s, 9, CH3), 7.27-7.57 (m, 3, H3,6,7), 7.77-8.13 (m, 4, H1,4,5,8),and 8.30 ppm (apparent s, 2, Hg.10). Compound 9 was also an oil: NMR 6 0.37 [s, 9, 3-Si(CH&], 0.54 [s, 9, l-Si(CH&], 7.27-7.50 (m, 2, H6,7), 7.73 (s, 1, Hz), 7.80-8.07 (m, 2, H5,8), 8.12 (s, 1, H4), 8.37 (s, 1, H i d , and 8.54 ppm (s, 1, Hg); the peaks a t 7.73 and 8.12 designated as singlets appeared to exhibit a small additional coupling ( J N 2 Hz) not well resolved.
Acknowledgment. S u p p o r t of this research by the US. Public Health Service (N01-CP-033385) is gratefully acknowledged. The HX-270 Bruker superconducting NMR spectrometer was provided through the University of Chicago Cancer Research Center G r a n t CA-14599. We also wish t o t h a n k Dr. Peter W. Rabideau for helpful discussion concerning assignment of several of the structures based on NMR spectral data. R e g i s t r y No.-1, 18002-83-0; 2, 56272-35-6; 3, 56272-36-7; trans-4, 56272-37-8; cis-4, 56272-38-9; trans-5, 56272-39-0; 7, 56272-40-3; 8, 56272-41-4; 9, 56272-42-5; 9,10-dihydroanthracene, 613-31-0; MesSiCl, 75-77-4.
References and Notes (1) J. A. Sperry, Ph.D. Thesis, University of Leicester, 1960; cf. R. Taylor, Tetrahedron Lett., 435 (1975). (2) Similar reaction was reported to afford a 30% yield: cf. C. Eaborn, 2. Lasockl, and J. A. Sperry, J. Organornet. Chem., 35 (1972). (3) P. P. Fu. R. G. Harvey, J. W. Paschal, and P. W. Rabideau, J. Am. Chem. SOC.,97, 1145 (1975). (4) R. G. Harvey and H. Cho, J. Am. Chem. SOC.,96,2434 (1974). (5) P. P. Fu and R. G. Harvey, Tetrahedron Lett., 3217 (1974). (6) M. Malenthal, M. Hellman, C. P. Haber, L. A. Hymo, S. Carpenter, and A. J. Carr, J. Am. Chem. SOC.,76,6392 (1954). (7) P. W. Rabideau, R. G. Harvey, and J. B. Stothers, Chem. Commun., 1968 (1969): A. W. Brinkmann, M. Gordon, R. G. Harvey, P. W. Rabideau, J. B. Stothers, and A. L. Ternay. Jr., J. Am. Chem. SOC.,92, 5912 (1970). (8) G. Stucky, Adv. Chem. Ser., 130, 56(1974). (9) A. M. Jeffrey, H. J. Yeh, D. M. Jerina, T. R. Patel, J. F. Davey, and D. T. Gibson, Biochemistry, 14, 575 (1975). (IO) A. D. Petrov and T. I. Chernysheva. Dokl. Akad. Nauk SSSR, 84, 515 (1952); Chem. Abstr., 47,3288 (1953). (1 1) Silyllithium compounds have been observed to add to double bonds: cf. H. Gilman and H. Winkler in “Organometallic Chemistry”, H. Zeiss, Ed.. Reinhold, New York, N.Y., 1960, p 322. (12) H. Alt, E. Franke, and H. Bock, Angew. Chem., 81, 538 (1969); Angew. Chem., int. Ed. fngl.., 8, 525 (1969). (13) P. P. Fu and R. G. khJey. unpublished results.
