Reactions of quinones with aromatic ethers. Part V. Triphenylene-1,4-quinones from 2,3-diaryl-1,4-benzoquinones

摘要

568 J.C.S. Perkin IReactions of Quinones with Aromatic Ethers. Part V.l Triphenylene-1.4-quinones from 2,3-Diaryl-1,4-benzoquinonesBy Robert Buchan, Chemistry Department, Robert Gordon‘s Institute of Technology, Aberdeen AB1 1 HG2.3-Diaryl-1.4-benzoquinones, prepared by the Meerwein arylation of other benzoquinones, undergo Schollreactions on treatment with acids and oxidising agents with the formation of triphenylene-1.4-quinones.Oliver C. Musgrave,* Chemistry Department, The University, Old Aberdeen AB9 2UEFOR work associated with the synthesis of triphenylene-diquinones we required 2,3-, 2,5-, and 2,6-bis-(3,4-di-methoxyphenyl)-l,4-benzoquinone. The Meenvein aryl-ation of chlorobenzoquinone has been shown to give allthree possible disubstituted products and we found that2-(3,4-dimethoxyphenyl)-l,4-benzoquinone reacted withdiazotised 3,4-dimethoxyaniline in a similar manner inthe presence of sodium acetate to give the desired 2,3-(7.1y0), 2,5- (O*6y0), and 2,6- (2.5%) diarylquinones. Thedirect arylation of 1,4-benzoquinone itself gave the sameproducts more conveniently and in similar yields.Thehigh proportion of the 2,3-isomer is noteworthy as related“0 treactions have previously* been thought to give only2,5-diarylquinones. The n.m.r. spectrum indicated theorientation of the substituents in the 2,3-diarylquinone,the proximity of the aromatic rings leading to theirshielding each other’s meta-methoxy-protons and aro-matic protons. We established the structures of the 2,5-and 2,6-isomers by chlorinating them with hydrochloricacid followed by iron(II1) chloride. The 2,5-diarylquin-1 Part IV, 0.C. Musgrave and C. J. Webster, J.C.S. Perkin I,a B. W. Birrell, R. Buchan, and 0. C. Musgrave, Chem. Comm.,J. F. Bagli and P. L‘Ecuyer, Canad. J. Chem., 1961,39, 1037.4 P. Brassard and P. L’gcuyer, Canad. J . Chem., 1968, 36,709; M. Akagi and K. Hirose, J . Pharm. SOC. Japan, 1942,62,191(Chem. Abs., 1961, 45, 6169d).1974, 2263.1969, 1341.one gave the known 3,6-dichloro-derivative [I; X == c1, Y = 3,4-(MeO),C6H3] and the 2,6-diarylquinonegave the known ti 3,5-dichloro-isomer [I; X = 3,4-(MeO),C6H3, Y = 2 = Cl]. In each case we also isolatedthe corresponding monochloro-derivative. The 2,3-diarylbenzoquinone [I; X = Y = H, 2 = 3,4-(MeO),-C6H3! behaved in a different way when subjected to thechlorination procedure. The product was an inseparablemixture which appeared from its spectral properties tobe composed of derivatives of the triphenylene-l,4-quin-one (11; X = H, Y = 2 = MeO).Such compounds havenot been described previously and we have therefore in-vest igated their format ion further.The conversion of a 2,3-diaryl-l,4-benzoquinone into atriphenylenequinone clearly involves an acid-catalysedScholl reaction between the two aryl nuclei and, inagreement with this, we found that anhydrous aluminiumchloride in carbon disulphide effected the cyclisation ofthe quinone [I; X = Y = H, 2 = 3,4-(MeO),C,H3]under mild conditions. The product obtained by theiron(m) chloride oxidation of the resulting quinol was thetriphenylenequinone (11; X = H, Y = 2 = MeO).Theyield (32%) was improved when 2,3-dichloro-5,6-di-cyano-l,4-benzoquinone was added to the reacton mix-ture but an attempted cyclisation with aqueous 70% v/vsulphuric acid gave only a little of the compound. Thesymmetrical structure of the triphenylenequinone fol-lows from the simplicity of its n.m.r. spectrum, whichshows singlets corresponding to twelve methoxy-protons(of two types), two quinonoid protons, and four aromaticprotons, two of which (H-5 and H-12) are strongly de-shielded by the adjacent carbonyl groups6In order to assess the utility of this reaction we neededsome related 2,3-diaryl-1,4-benzoquinones. 2,3-Di-chloro-I ,4-benzoquinone has only two adjacent positionsavailable for further substitution and on treatmentwith diazotised 3,4-dimethoxyaniline gave the aryl-quinone (I; X = Y = C1, 2 = H). Further aryl-ation with the appropriate diazonium compoundsafforded the 2,3-diarylquinones [I; X = Y = C1, 2 =and (I; X = Y = C1, 2 = Ph).Each of these under-went cyclisation and oxidation on treatment with aque-ous 70% v/v sulphuric acid and chloranil, giving the tri-phenylenequinones (11; X = C1, Y = 2 = MeO) (88%),(11; X = C1, Y = MeO, 2 = H) (67y0), and (11; X =3,4-(Meo),C6H31, (I; X = Y = C1, Z = 3-MeOC6H4),5 L. M. Jackman and S. Sternhell, ‘Applications of NuclearMagnetic Resonance Spectroscopy in Organic Chemistry, ’Pergamon, Oxford, 1969, 2nd edn., ch.2-2.6 0. C. Musgrave and C. J. Webster, J.C.S. Perkin I , 1974,2260.7 0. C. Musgrave, Chem. Rev., 1969,69,4991975 569C1, Y = 2 = H) (lo%), respectively. The diarylbenzo-quinone [I; X = Y = C1, 2 = 3,4-(MeO),C6HA alsounderwent cyclisation on treatment with hydrochloricacid and, after treatment with iron(II1) chloride, affordedthe expected dichlorotriphenylenequinone (I1 ; X = C1,Y = 2 = MeO) (32%). The relevant n.m.r. signals andthe U.V. and visible absorption spectra of the productsresemble closely those of the unchlorinated quinone (I1 ;X == H, Y = 2 = MeO). In the mass spectrometer thefour triphenylenequinones undergo little fragmentation,the only abundant fragment ion in each case being formedby the loss of Me' and CO. The quinone (11; X = C1,Y = Z = MeO) formed a leucoacetate which gives theexpected n.m.r.signals and which shows U.V. absorptionresembling closely that of 2,3,6,7,10,11-hexamethoxy-t riphen ylene.The major product obtained from the reaction of thebenzoquinone (I; X = Y = C1, 2 = Ph) with aqueoussulphuric acid and chloranil is a colourless phenol,C,H,4Cl,04, which, by analogy with similar productsfrom other arylquinones, we formulate as the dibenzo-furan (111). Its U.V. absorption resembles that of 1,3-dichloro-7,8-dimethoxydibenzofuran-2-ol, and its n .m.r.signals agree well with those of related dibenzofurans.We attribute the unusually high values for the resonancesof the C-8 methoxy-protons and the C-9 proton to theshielding effect of the phenyl The relative diffi-culty of effecting a Scholl reaction with the unactivatedphenyl group is no doubt the reason for the preferredformation of this compound.Veratrole reacts with 2,5- and 2,6-&chlorobenzoquin-one in aqueous 70% v/v sulphuric acid to give thecorresponding diarylquinones and it appeared possiblethat 3,4,3',4'-tetramethoxybiphenyl and 2,3-dichloro- 1,4-benzoquinone might react together under similar condi-tions to provide an alternative route to the triphenylene-quinone (11; X = C1, Y = 2 = MeO).In fact the di-chloroquinone effected the oxidation of the biphenyl andthe only product obtained was 2,5,6,9,12,13-hexameth-oxydibenzo Wg ,o$]naphthacene- 1,8-quinone .9The mass spectra of the 2,3-, 2,5-, and 2,6-bis-(3,4-dimethoxyphenyl)-l,4-benzoquinones show differenceswhich can be correlated with their structures.The 2,5-isomer, in which each carbonyl group is adjacent to anaryl group, readily loses one or two methoxyl radicals toform ions for which structures such as (IV) and (V),respectively, may be written. In contrast, the 2,6-iso-mer, which has only one carbonyl group adjacent to anaryl group, loses carbon monoxide followed by onemethoxyl radical. Fragmentation of the 2,3-isorner ismore complicated. This has a carbonyl group adjacent toeach aryl group and, as expected, loses one or two meth-oxyl radicals. The proximity of the two aryl groupsappears to be responsible for the second mode of frag-mentation in which the molecular ion loses a methyl* 0.C. Musgrave and C. J. Webster, J . Chem. SOC. (C), 1971,0. C. Musgrave and C. J. Webster, J . Chem. SOC. (C), 1971,1397.1393.lo Cf. R. Pummerer and H. Fiedler, Ber., 1927, 60, 1439.radical followed by a methoxyl radical or methanol. Noappreciable cleavage of the quinone ring occurs in thiscase.The 2,3-dichloro-5,6-diarylquinones (I; X = Y = C1,2 = Ar) do not possess definite m.p.s but decompose onbeing heated. We associate this behaviour with the easewith which these compounds can cyclise. Some of themonoarylbenzoquinones prepared during this workshowed variations in their solid-state properties depend-ing on how they had been purified.1° For example,sublimed specimens of 2-(3,4-dimethoxyphenyl)-l,4-benzoquinone exhibited i.r.absorption different fromthat of crystallised samples and the related 2-(2-chloro-4,5-dimethoxypheny1)- 1,4-benzoquinone crystallisedfrom ethanol either as orange rhombohedra or as violetneedles, depending largely on the rate of cooling of thesolution.EXPERIMENTALU.V. absorption spectra were measured for solutions inchloroform, unless stated otherwise, with a Unicam SP 800spectrophotometer ; i.r. absorption spectra were obtainedfor Nujol mulls with a Unicam SP 200 or 200G spectro-photometer. N.m.r. spectra were recorded for solutions in[2H]chloroform with Varian A60 (60 MHz) and HA-100 (100MHz) spectrometers (tetramethylsilane as internal standard).Mass spectra were obtained with an A.E.I. MS9 instrument.Silica gel (Merck Kieselgel GF2S4) was used for t.1.c.' Lightpetroleum ' refers to the fraction of b.p. 40-60".2-(3,4-Dimethoxy$henyl)-1,4-benzoquinone.-This l1 crys-tallised from ethanol-acetone as red rhombohedra m.p.133-134" (1it.,l1 134-136", 134-135"), & (EtOH) 246-6(log E 4.30) and 445 nm (3.42), Ai,n. 276 nm (log e 3-84), v-1645 cm-1 (quinone G O ) , 6 3.91 (6H, s, ArOCH,), 6.81 (3H,s, QH), and 6.95-7-25 (3H, m, ArH). After sublimation at90" and 0.1 mmHg i t had m.p. 135-136", vWx 1656 cm-1.The two specimens showed identical i.r. spectra in CS, solu-tion [v,, (CS,) 1653 cm-l].Arylation of 1,4-Benzoquinone.-A solution of the di-azonium salt prepared from 3,4-dimethoxyaniline 18 (3-83 g)in 3~-hydrochloric acid (32 ml) and sodium nitrite (1.73 g)in water (15 ml) at 0" was added, together with a solution ofanhydrous sodium acetate (7 g) in water (25 ml), to a vigor-ously stirred solution of 1,4-benzoquinone (2-7 g ) in acetone(125 ml) a t 10".Stirring was continued for 2 h, water (100ml) was added, and the mixture was concentrated (to 200ml) under reduced pressure. Extraction with chloroformgave an oily solid which was chromatographed on a columnof silica gel. Elution successively with benzene and ben-zene-chloroform (1 : 1) gave 2-( 3,4-dimethoxyphenyl)- 1,4-benzoquinone (1.92 g), m.p. 133-134', followed by a violetsolid which was separated by t.1.c. [benzene-ethyl acetate(20: l)] into three bands. The first of these afforded 2,5-bis- (3,4-dimethoxyphenyl) - 1, 4-benzoquinone, which crystal-lised from chloroform-ethanol as orange needles (60 mg),m.p.194-195" (Found: Mf', 380.1255. C,,H2,,0, re-quires M , 380-1260), A,,, 255 (loge 4-39), 288 (4-29), and 437nm (3*79), A i d . 364 nm (log E 3*50), vmx. 1648 cm-l (quinoneGO), 6 3.93 (12H, s, ArOCH,), 6-90 (2H, s, QH), and 6.85-7-31 (6H, m, ArH), m/e 380 (loo%, M+'), 349 [41%,l1 M. Akagi, J . Pharm. SOC. Japan, 1942, 62, 202 (Chem. Abs.,1961,45, 2898e) ; P. Brassard and P. L'gcuyer, Canad. J . Chem.,1968, 36, 700.l2 F. Pollecoff and R. Robinson, J . Chem. Soc., 1918, 113, 646570 J.C.S. Perkin I(M - MeO)+]. 321 [12%, (349 - CO)-+], 318 [47%, (349 -MeO)+'], and 162 (31%, [3,4-(MeO)2C,H3CZCH]+'), m* 320.5(380 + 349) and 289-7 (349 ---t 318). The product fromthe second band crystallised from ethanol to give 2,6-bis-(3,4-dimethoxypkenyZ) - 1 ,Pbenzoquinone as violet needles(0.25 g), m.p.168-169-5' (Found: M+', 380.1263.C22H2006 requires M , 380-1260), Lx 280.5 (log E 4.26) and460 nm (3.72), A i d . 360 nm (log E 3.34); vmX. 1660sh and1647 cm-l (quinone GO), v- (2% CHC1,) 1665 and 1647cm-l, 6 3.92 (12H, s, ArOCH,), 6.85 (2H, s, QH), and 6.88-7.28 (6H, m, ArH), m/e 380 (loo%, M f ' ) , 352 [9%, (M -CO)+'], 337 [ll%, (352 - Me)+], 321 [13%, (352 - MeO)+],and 162 {26%, [3,4-(MeO)2C,H,CXH]+'), m* 326.0 (380-352) and 322.6 (352 --c 337). The third band afforded2,3-bis-(3,4-dimethoxy~henyZ)-l,4-benzoquinoneJ which crys-tallised from chloroform-ethanol as clusters of deep redrhombohedra (0.60 g) , m.p. 199-200-5° (Found: M+',380.1263. C22H200, requires M , 380.1260), Lx 283 (log E4.01) and 480 nm (3~38)~ vInax.1660 and 1651 cm-l (bothquinone C=O), 6 3.61 and 3.84 (each 6H, s, 3- and 4-OMe),6.90 (2H, s, QH), and 6.51-6-72 (6H, m, ArH); m/e 380(loo%, M+'), 365 (7%, (M - Me)'], 349 [7%, ( M -MeO)+], 334 [7%, (365 - MeO)+*], 333 [11%, (365 -MeOH)+], and 318 [19%, (349 - MeO)+'], m* 350.5(380 --w 365), 320-5 (380 + 349), 303.8 (365 + 333),and 289.7 (349 --+c 318).Arylation of 2-( 3,4-Dimethoxyphenyl)- 1,4-benzoquinone.-The reaction of the buffered diazonium solution preparedfrom 3,4-dimethoxyaniline (0.7 g) with 2-(3,4-dimethoxy-pheny1)-l,(dbenzoquinone (0.73 g) in acetone (100 ml) andwater (100 ml) at - 5 O , as described above for benzoquinone,gave the unchanged arylbenzoquinone (0.17 g), and 2.5-( 10 mg) , 2,6- (40 mg) , and 2 , 3-bis- (3 , 4-dimethoxypheny1)-1 , 4-benzoquinone (0- 1 1 g) .A similar reaction with acetic acid (25 ml) as solvent in-stead of aqueous acetone afforded the unchanged arylbenzo-quinone (0.20 g), and 2,6- (60 mg) and 2,3-bis-(3,4-dimeth-oxyphenyl) - I ,4-benzoquinone (80 mg) .2,3-DichZoro-5-( 3,4-dimethoxyphenyZ) -1 ,&bemopinone.-The reaction of the buffered diazonium solution preparedfrom 3,4dimethoxyaniline (1.2 g) with 2,3-dichloro-1,4-benzoquinone 1, (0-55 g) in acetone (70 ml) at 0" as describedabove for benzoquinone gave the aryZbenzoquinone, whichcrystallised from chloroform-ethanol as violet needles (0.31g), m.p.205-206' (Found: C, 83.5; H, 3.3; C1, 22.7;MeO, 20.5.C,4H,oCl,04 requires C, 53.7; H, 3.2; C1,22-65;2Me0, 19.85y0), 260 (log 8 4~22)~ 278 (4.141, 337 (3.66),and 508 nm (3~46)~ urn= 1675 and 1652 cm-l (both quinoneC=O), 6 3.90 and 3.92 (both 3H, s, ArOCH,) and 6-80-7*10(4H, m, ArH and quinone H).2- (2-Chloro-4,5-dimethoxy~henyZ) - 1 , 4-benzoquinone .- Thereaction of the buffered diazonium solution prepared from2-chloro-4,5-dimethoxyaniline 8 (0.38 g) with 1.4-benzo-quinone (0.25 g ) in water at loo, as described above, gave thechloroqzlinone (0.28 g ) , which crystallised from ethanol, onbeing cooled slowly, as orange rhombohedra, m.p. 130-130.5" (Found: C, 60.4; H, 4.0; C1, 12-6; MeO, 22-6.ClIH,,C104 requires C, 60.35; H, 4.0; C1, 12.75; 2Me0,22.25%. Found: M+', 278-0349.C&11a5C104 requiresM , 278.0346), &. (EtOH) 244 (log t 4-39), 283 13-81) , and427 nm (3.04), 324 (log E 3-04) and 345 nm (2-98), vmz1660 cm-l (quinone GO), 6 3.85 and 3.90 (each 3H, s,ArOCH,) and 6.69-6-93 (5H, m, ArH and quinone H).Crystallisation of the compound from ethanol with rapidcooling and agitation gave violet needles, vmaK 1658 cm-l,which changed into the orange form a t 120'. The i.r.spectra of Nujol mulls of the two specimens were different.2,3-DichZoro-5,6-bi.s-( 3,Pdimethoxyphen-yZ)- 1,4-benzoquin-one.-The reaction of the buffered diazonium solution prc-pared from 3,4-dimethoxyaniline (0.30 g) with 2,3-dichloro-5-( 3,4-dimethoxyphenyl)-1,4-benzoquinone (0.30 g) inacetone (250 ml) at lon, as described above for benzoquinone,gave a mixture which was separated by crystallisation fromchloroform-ethanol and t.1.c.[benzene-ethyl acetate (10 : l)]into the unchanged arylbenzoquinone (0.21 g) and a violetsolid (50 mg) which by sublimation a t 120' and 0.1 mmHggave the diarylbenzoquinone (Found : M+', 44800484.C22Hl,36Cl,0, requires M , 448.0480) , Lz (EtOH) 253 (log z4-29), 326 (3.58), and 466 nm (3.28), AiM. 273 nm (log E 4-21),vmK 1670 cm-l (quinone C=O) ; 6 3.62 and 3.84 (each 6H, s,3- and 4-OMe), and 6-50-6.80 (6H, m, ArH), mle 448(M - Me0 - MeO)+'], and 382 [9%, (M - C1 - MeO)+'].The product, a violet solid, did not have a definite m.p.T.1.c. (penzene-ethyl acetate (10 : 1) and benzene-lightpetroleum (9 : 1)J showed it to be homogeneous.2,3-DichZoro-5- (3,4-dimethoxy$henyZ) -6-( 3methoxyphenyZ) -1,4-benzoqzcinone.-The reaction of the buffered diazoniumsolution prepared from 3-methoxyaniline (0.25 g) with 2,3-dichloro-5-( 3,4-dimethoxyphenyl)-l,4-benzoquinone (0- 10 g)in acetone (150 ml) at 12O, as described above for benzo-quinone, gave a mixture which was separated by t.1.c.(benzene) into the unchanged arylbenzoquinone (65 mg)and the diarylbenzoquinone (14 mg) (Found: M+', 418.0374.C21H163SCl,0s requires M , 418*0375), Lx 264 (log E 4-27),332 (3*67), and 517 nm (3*30), Xjnfl, 275 nm (log E 4-22), vmx.1673 (quinone G O ) , 6 3.58, 3-66, and 3.84 (each 3H, s,ArOCH,), and 6.42-7.32 (7H, m, ArH), m/e 418 (100%,M+'), 371 [11%, (M - Me - MeOH)+], 362 [lo%, (M -Me0 - Cl)+'], and 340 [9%, (M - Me - C1 - CO)+*].The product, a violet solid, did not have a definite m.p.T.1.c.{benzene-ethyl acetate (10 : 1) and benzenelightpetroleum (9 : l)J showed it to be homogeneous.2,3-DichZoro-5-(3,4-dimethoxy~henyZ) -6-phenyl- 1,4-benzo-quinone.-The reaction of the buffered diazonium solutionprepared from aniline (0.37 g) with 2,3-dichloro-5-(3,4-di-methoxyphenyl)-l,4-benzoquinone (0.10 g) in acetone (150ml) at 8 O , as described above for benzoquinone, gave a redsolid which, after purification by t.1.c. (benzene) afforded thediaryEquinone as a violet solid (30 mg) (Found: M+',388.0267. C2aH1a3sC1,04 requires M , 388-0289), & 262(log t 4-27], 331 {3-73), and 522 nm (3.25), Aina, 257 (log e4.25), and 287 nm (3.963, v- 1668 (quinone C=O), 6 3.56and 3-85 (both 3H, s, 3- and 4-OMe), and 6.45-7.35 (8H.m,ArH), m/e 388 (loo%, M+'), 322 (34%, (M - Me0 -Cl)+'], and 310 [15%, (M - Me - CO - CI)+']. Theproduct did not have a definite m.p. T.1.c. [benzene-ethylacetate (10 : 1) and benzene-light petroleum (9 : l)] showed itto be homogeneous.Chlorinatim of the Bis-(3,kdimethoxypJteptyl)- 1.4benzo-pwinones.-A mixture of 2,6-bis-( 3,4-dimethoxyphenyl)-lJPbenzoquinone (43 mg) and concentrated hydrochloric acid(20 ml) was boiled under reflux for 1.5 h, poured into water(150 ml), and shaken with chloroform. The dried chloru-form solution was shaken with iron(1ix) chloride (0.25 g),washed with 2~-hydrochloric acid and with water, dried,and evaporated. The resulting red solid was separated bypreparative t.1.c.[benzene-ethyl acetate (20 : l)] into start-13 J. B. Conant and L. F. Fieser, J. Amer. Chem. Soc., 1923,45,2194.(loo%, M"), 401 [8%, (M - CH, - CH,OH)+], 386 [8%1975ing material (10 mg), 2,6-dichloro-3,6-bis-(3,4-dimethoxy-phenyl)-l,4-benzoquinone (2 mg), m.p. 300-301" (lit.,6306*5-307-5"), and 3-chloro-2,5-bis-(3,4-dimethoxyphenyl)-1,4-benzoquinm (15 mg), red needles or orange plates (fromchloroform-ethanol), m.p. 208-209.5° (Found : M+*,414.0866. C,,Hl,36C10, requires M, 414-0870), kx 260(log E 4-37), 284 (4.28), and 464 nm (3-70), vmx. 1665 and 1643cm-l (both quinone GO), 6 3.90 (3H, s, ArOCH,), 3.95 (9H,s, ArOCH,), and 6.92-7.17 (7H, m, ArH and quinone H) ;m/e 416 [77%, (M + 2H)+'], 414 (loo%, M+'), 383 [19%,(M - MeO)+], 379 [12%, (M - Cl)+], 352 [50%, (383 -MeO)+*], 348 [95%, (383 - Cl)+'], and 189 (22%, [3,4-(MeO),C,H,~CO]+}, m* 354-3 (414 ---t 383), 323.4(383 + 352), 319.6 (379 --+ 348), and 316.2 (383 ---t 348).A similar reaction with 2,6-bis-(3,4-dimethoxyphenyl)-l,4-benzoquinone (70 mg) gave starting material (6 mg), 2,6-di-chloro-3,5-bis-(3,4-dimethoxyhenyl)-1,4-benzoquinone (6mg) as violet needles (from chloroform-ethanol), m.p.212-2 13.5" (lit. ,, 2 1 1-2 13"), and 2-chZoro-3,5-bis-(3,4-dimethoxy-phenyZ)-l,4-benzoquinone (43 mg) as violet needles (fromchloroform-ethanol), m.p. 174-5-177" (Found : M+',414.0869. C,2H1,36C10, requires M, 414.0870), Amx. 257(log E 4-40), 280 (4-30), 320 (3-50), and 490 nm (3-66), vmk1657 cm-l (quinone GO), 6 3.90 and 3.93 (both 6H, s,ArOCH,) and 6.80-7.18 (7H, m, ArH and quinone H), m/e414 (loo%, AT+'), 383 [6%, (M - MeO)+], 379 [7%, (M -Cl)'], 365 [25%, (383 - CO)+], 351 [7%, (379 - CO)+], and189 { 12%, [3,4-(Me0),C,H3~CCO]+), m* 354.3 (414 -+383), 346.9 (414 ---t 379), and 329.1 (383 + 355).A similar reaction with 3-chloro-2,6-bis-( 3,4-dimethoxy-pheny1)- 1,4-benzoquinone (35 mg) gave 2,6-dichloro-3,6-bis-(3,4-dimethoxyphenyl)-l,.Q-benzoquinone (5 mg) and start-ing material (20 mg).Cyclisation of 2,3-Bis-(3,4-dimethoxyfihenyt)-1,4-benzo-quinone.-(a) With aluminium chloride. A mixture of thebenzoquinone (75 mg), anhydrous aluminium chloride (0.5 g)and carbon disulphide (100 ml) was stirred a t room tempera-ture for 3 days and then added to a mixture of ice (30 g) andM-sulphuric acid (10 ml).The carbon disulphide wasevaporated off under reduced pressure and the aqueousmixture was shaken with chloroform. Anhydrous iron(n1)chloride (0.20 g) was added to the dried chloroform layer,which was then washed with 2~-hydrochloric acid andevaporated. The residual solid was separated by t.1.c.[benzene-ethyl acetate (4 : l)] into starting material (18 mg)and 6,7,10,1 l-tetramethoxytriphenylene-1,4-quinone, whichcrystallised from chloroform-ethanol as violet needles (24mg, 32y0), m.p. 289-291' (Found: M+', 378.1091,C2,HI8O, requires M , 378-1103), Lx 271 (log E 4-76), 326(3.63), 346 (3-49), and 494 nm (3.76), Ai,fl. 296 (log E 4-24),301.5 (4.18), and 312 nm (3.92), vwx.1645 cm'l (quinoneGO), 6 4.08 and 4.11 (each 6H, s, ArOCH,) , 6.82 (2H, s, H-2and H-3), 7-58 (2H, s, H-8 and H-9), and 8-98 f2H, s, H-5and H-12), m/e 378 (loo%, M+'), 335 [24%, (M - CH, -CO)+), and 189 (lo%, M2+).The addition of 2,3-dichloro-5,6-dicyano- 1,4-benzaquin-one (0.15 g) to the reaction mixture gave a higher (50%)yield of the triphenylenequinone.(b) With aqueous sulphuric acid. A mixture of the benzo-quinone (100 mg) and aqueous 70% v/v sulphuric acid (15ml) was shaken for 2 h, kept for 3 days a t room temperature,and poured into water (60 ml). Treatment as in (a) gavestarting material (2 1 mg) and the triphenylenequinone2,3-Dichlw0-6,7,lO, 1 1-tetramethoxytriphenyZene- 1,4-quin-(3 mg).571one.-(a) A mixture of 2,3-dichloro-5,6-bis- (3,4-dimethoxy-phenyl)-l,4-benzoquinone (40 mg), chloranil (100 mg), andaqueous 70% v/v sulphuric acid (40 ml) was shaken for 24 hand diluted with water (100 ml).Extraction with chloro-form gave a violet solid which was separated by t.1.c.[benzene-ethyl acetate (10 : l)] into chloranil and the tri-phenylenequinone, which crystallised from chloroform-ethanol as violet needles (35 mg), m.p. 310-313" (Found:M+*, 446-0338. C,,H,,35C120, requires M, 446-0324), I,,276 (log E 4-83), 355 (3-61), and 532 nm (3.80), Ajnfl. 300 (log E4.39), 316 (4.07), and 328 nm (3.84), v-. 1658 cm-1 (quinoneG O ) , 6 4.08 and 4.13 (each 6H, s, ArOCH,), 7.62 (2H, s, H-8and H-9), and 8.78 (2H, s, H-5 and-l2), m/e 446 (loo%,M+'), 403 [27%, (M - CH, - CO)+], and 223 (70/,, M2+).(b) A mixture of the diarylbenzoquinone (25 mg) and con-centrated hydrochloric acid (25 ml) was boiled under refluxwith stirring for 3 h, poured into water (100 ml), and ex-tracted with chloroform.The dried chloroform layer wasshaken with anhydrous iron(II1) chloride (0.25 g), washedwith 2~-hydrochloric acid and with water, dried, andevaporated. Purification of the resulting solid by t.1.c.[benzene-ethyl acetate (9 : l)] gave the triphenylenequinone2,3-Dichloro-6,7,10,11-tet~amethoxytri~henyZene- 1,4-diyZDiacetate.-A mixture of 2,3-dichloro-6,7,1O,ll-tetrameth-oxytriphenylene-1,4-quinone (27 mg), acetic anhydride (10ml), zinc dust (0.20 g), and triethylamine (0.2 ml) washeated under reflux for 1 h and poured into hot water (50ml) .Extraction with chloroform gave the Zeucoacetate,which crystallised from chloroform-ethanol as needles(28 mg), m.p. 231-5-233" (Found: M+', 534.0642.C,,H,,3~C137C108 requires M, 534-0662), & 287 (log E 4-93),361 (3*53), and 379 nm (3.48), Awl. 258 (log E 4.42), 269(4-59), 277 (4.73), 304 (4.54), and 339 nm (3.66), vmx. 1765and 1755 cm-l (acetate GO), 6 2.47 (6H, s, CH,CO,Ar), 4.04and 4-08 (both 6H, s, ArOCH,), and 7.70 and 8-46 (both 2H,s, H-8 and H-9, H-5 and H-12), m/e 532 (20%, M+'), 4902,3-D~chlwo-6,7,11-brimethoxytviphenyZene- 1,4-quinme.-A mixture of 2,3-dichloro-5-(3,4-dimethoxyphenyl)-6-~3-methoxyphenyl)-l,4-benzoquinone (12 mg), chloranil (25mg), and aqueous 70% v/v sulphuric acid (20 ml) was shakenfor 2 h, kept overnight, and diluted with water (100 ml).Extraction with chloroform gave a violet solid which wasseparated by t.1.c.[benzene-ethyl acetate (5 : l)] intochloranil and the triphenyZenequinone, which crystallisedfrom chloroform-ethanol as violet needles (8 mg), m.p.270-272" (Found : M+', 416-0221. C,1H1,36Cl,0, requiresM , 416-0218), A,, 273 (log c 4-81) and 536 nm (3-60), Xinfl.268 (log E 4-75), 292 (4.38), 303 (4-25), 320 (3.93), and 354 nm(3.44), v,, 1660 cm-l (quinone GO), 6 3.98, 4.04, and 4.10(each 3H, s, ArOCH,), 7.63 (lH, s, H-8), 8.60 (lH, s, H-5),and 7.20-8.68 (3H, m, H-9, H-10, and H-12), m/e 416(loo%, M+*), 373 [21%, (M - Me - CO)+], and 208CycZisation of 2,3-Dichloro-5-( 3,4-dimethoxyphenyt)-6-phenyZ- 1,4-benzoquin.~ne.-A mixture of the quinone (20 mg),chloranil (40 mg), and aqueous 70% v/v sulphuric acid (20ml) was shaken for 4 h, kept overnight, and diluted withwater (60 ml).Extraction with chloroform gave a redsolid which was separated by t.1.c. (benzene) into (a) chlor-anil, (b) 2,3-dichloro-6,7-dimethoxytriPhenyZene- 1,4-quinme,which crystallised from chloroform-ethanol as red needles(2 mg), m.p. 247.5-249.5" (Found: M+*, 386-0101.C2,H1236Cl,04 requires M , 386-0113), 268 (log E 4-75) and(8 mg) *[19%, (M - CH,CO)+'], and 448 [loo%, (M - 2CH,CO)+'].(lo%, M2+)57 2 J.C.S. Perkin I514 nm (3~64)~ Ai,fl. 264 (4.72), 290 (4~30)~ 310 (4.06), 321(3.92), and 350nm (3.32), vmx. 1662cm-l (quinoneC=O), 64.12and 4-16 (each 3H, s, ArOCH,), 7.99 (lH, s, H-8), 8-88 (lH,s, H-5), and 7.68-9.27 (4H, m, H-9, H-10, H-11, and H-12),m/e 386 (loo%, Mf'), 343 [15%, (M - CH, - CO)+], and193 (8%, M"), and (c) 3,4-dichloro-7,8-dirnethoxy- l-phenyl-dibenzo fuva.pz-2-0Z, which crystallised from chloroform-ethanol as needles (15 mg), m.p. 173.5-174-5' (Found:M+' , 388.027 1. C20Hl,35C1,0, requires M , 388-0269), kx.(EtOH) 250 (log e 4.23) and 319 nm (4-35), Ainfl. 223 (log E4.46) and 263.5 nm (4.13), vmx. 3535 cm-1 (phenolic OH), 63.56 and 3-92 (both 3H, s, 8- and 7-OMe), 5-46 (lH, s,ArOH), 6.36 (lH, s, H-9), 7.10 (lH, s, H-6), and 7-3A7-55(5H, m, C,H,Ar), m/e 388 (loo%, M+'), 373 [8%, ( M -Me)+], 341 [8%, (373 - MeOH)+], 329 [9%, (M - Me0 -CO)+], and 310 [23%, (373 - COCl)+'], m* 358.6 (388-373), 311.8 (373 --+ 341), and 257.7 (373 ---+ 310).Reaction of 2,3-Dichloro-1,4-benzoqz&inone with 3,3',4,4'-Tetramethoxybi#henyl.-A mixture of the benzoquinone (0.5g), the biphenyl (0.13 g ) , and aqueous 70% v/v sulphuricacid (15 ml) was shaken for 3 h, kept at room temperaturefor 4 days, and shaken with water (100 ml) . Extraction ofthe resulting solid with chloroform removed startingmaterials and 2,3-dichloroquinol and afforded 2,5,6,9,12,13-hexamethoxydibenzo[fg,o~]naphthacene- 1 , 8-quinone (90mg) as an insoluble blue residue.We thank the Physico-Chemical Measurements Unit,Aldermaston, for the mass spectra.[4/1996 Received, 30th September, 1974