Amine oxidation and the chemistry of quinone imines. Part II. 2,5-Di-methoxy-4-t-butylaniline

摘要

J.C.S. Perkin IAmine Oxidation and the Chemistry of Quinone Imines. Part 11.l 2,5-Di-methoxy-4-t- butylanilineBy R. K. Haynes and F. R. Hewgill," Department of Organic Chemistry, University of Western Australia, Nedlands,Western AustraliaThe oxidation of 2,5-dimethoxy-4-t-butylaniline (1 ) by alkaline ferricyanide or silver oxide gives 2,2'.5,5'-tetra-methoxy-4,4'-di-t-butylazobenzene (2) and 3,8-dimethoxy-2,7-di-t-butylphenazine (3). Chromatographicseparation of the oxidation products on neutral alumina gives rise to six other products, including three N-aryl-p-quinone irnines (4). (6), and (7), a tetrameric product (5), and a phenoxazone ( 8 ) . Evidence is presented for thestructures of these compounds, and their origin i s discussed.The formation of the phenazine (3) provides clear evidence for the cyclisation of an intermediate N-aryl-o-quinone di-imine (1 1) under these conditions.Isolation of the debutylated quinone imine (7) substantiatesassumptions made in the previous paper.THE oxidation of 2-anilinoanilines bearing a replaceablesubstituent, such as halogen or an alkoxy-group, in the2'-position invariably results in the formation of aphenazine, with the elimination of this substituent .2It has also been reported recently that oxidation of5- t- but yl-o-anisidine 374 andwith lead dioxide in refluxing benzene gives 2,7-di-t-butylphenazine. This result is of interest as thepresence of the o-alkoxy-group would prevent theformation of an intermediate 2-anilinoaniline, and itseems likely that under these conditions the expectedN-phenyl-o-quinone di-imine intermediate would haveThe Chemistry of Hetero-cyclic Compounds, Phenazines,' Interscience, New York, 1957,p.6.5- t- bu t yl-o-phenetidinePart I, R. K. Haynes and F. R. Hewgill, preceding paper. * G. A. Swan and D. G. I. Felton,undergone thermally induced cyclisation. To establishunequivocally whether such di-imines can cyclise tophenazines under the conditions of ferricyanide or silveroxide oxidation-a reaction that appeared not to takeplace during oxidation of 3-methoxy-4-t-butylaniline l-we have examined the oxidation of 2,5-dimethoxy-4-t-butylaniline (l), in which formation of a 2-anilinoanilineis similarly prevented. This amine was chosen becausethe expected phenazine (3) was available and otheroxidation products could readily be related to those ofthe monomethoxy-analogue .lOxidation of the aniline (1) with alkaline ferricyanide3 F.N. Mazitova and R. R. Shagidullin, Izvest. Akad. NaukS.S.S.R., Ser. khim., 1966, 1851 (Chem. Abs., 1957, 66, 75,774b).F. N. Mazitova, R. R. Shagidullin, and V. V. Abushaeva,Zhur. org. Khinz., 1967, 8, 878 (Chem. Abs., 1967, 67, 43,137a)1972 409and with silver oxide gave the products (2)-(8) in theyields shown. As in the previous oxidation,l unchangedaniline was always present at the end of the reactiontime when ferricyanide was used as oxidant, and noneof the quinonoid materials (4)-(8) were detected beforechromatographic fractionation of either oxidation mix-ture.Yields of the tetrameric compound (5) and of thephenoxazone (8) were not reproducible.(5) cn. 3'0Me0 moM e o wBu( 7 ) 0.3.0.5Figures represent yields () K,Fe(CN),, Ag,OPvoduct Identification.-The azobenzene (2) wasidentified spectrally, and synthesised by couplingdiazo t ised 2,5-dimet hox y-4-t-but ylaniline with 4-methoxy-3-t-butylphenol and methylating the product.The phenazine (3) produced was identical with thepreviously obtained pr0duct.lLike the corresponding product from 3-methoxy-4-t-butylaniline, the amino-quinone imine (4) could not becrystallised, but was similarly synthesised. Condens-ation of the aniline (1) with 6-imino-4-methoxy-3-t-butylcyclohexa-2,4-dien-l-one (9) gave the quinone imine(4) in 4 yield.The major product of this condensationwas compound (lo), which was identified by its n.m.r.and i.r. spectra, and was also formed by acid-catalysedcondensation of the amino-quinone imine (4) with (1).A small amount (1) of the phenazine (3) was alsoisolated from the condensation of (9) with (l), indicatingthat some addition of the aniline (1) had taken place atthe carbonyl group of (9) to produce the di-imine (ll),which had subsequently cyclised (Scheme 1).Ar = 2,5-(OMe),-4-ButC,H,SCHEME 1The assignment of structure (5) to the deep, indigo-blue product obtained from the ferricyanide oxidation isbased on the n.m.r. spectrum, which contained signalsfrom eight uncoupled ring protons, five methoxy-groups,and four t-butyl groups.Amine and quinone-carbonylabsorptions were absent from the i.r. spectrum. Thismaterial was formed when compound (10) was condensedwith the aniline (1).Compound (6) is the dimethoxy-analogue of theamino-quinone imine described in Part I,l which showedsimilar spectral characteristics. It was obtained in16 yield by condensation of 2-amino-5-t-butyl-l,4-benzoquinone with (1).The structure of compound (7) appears to be un-ambiguously suggested by its n.m.r. spectrum, whichdisplayed signals attributable to two aromatic and twovinylic protons, separate signals for four methoxy-groups,and only one t-butyl resonance. The i.r. spectrumshowed a single carbonyl absorption at 1652 cm-l, andthe U.V. spectrum A,, (log E) 213 (4.29), 298 (4.36), and487 (3.43) nm was similar to that of the syntheticquinone imine (12) A,,.(log E) 218 (4.04), 294 (4.22), and510 (3.43) nm.A r N M e o a A r MeoaN:;r 0( 1 4 ) (151Ar = 2,5-(OMe),-4-ButC6H2It was hoped that acid-catalysed condensation of theaniline (1) with 2,5-dimethoxy-fi-benzoquinone wouldgive (7), but in hot acetic acid two different productswere obtained. The first was identified as the anilino-quinone (13) by the presence of secondary amine (3320cm-l) and quinonoid (1662 and 1647 cm-l) bands in itsi.r. spectrum, and by the n.m.r. spectrum, which con-tained one t-butyl and three methoxy-signals. Spectro-scopic evidence indicated that the second compoundpossessed structure (14) or (15), but a distinction couldnot be made on this ground alone.However, when th410 J.C.S. Perkin Iquinone imine (7) was condensed with (1) in cold aceticacid, this material (14) or (15) was the sole product.This result is consistent with the proposed structure (7).The n.m.r. spectrum of the last quinonoid oxidationproduct (8) indicated the presence of two-t-butyl groups,one methoxy-group, and two vinylic and two aromaticprotons. The i.r. spectrum, with absorptions a t 1641and 1613 crn-l, indicated the presence of a quinonoidcarbonyl group.5 As empirical analysis showed thatthree oxygen atoms were present, one of these must bering-bridging, and this was confirmed by reductiveacetylation. The resultant diacetate had i.r. absorptionsattributable to 0-acetyl (1766 cm-l) and tertiary amide(1611 cm-l) groups, and hence the only structures thatfit the evidence are those of the two phenoxazones (8)and (16).The U.V. spectrum A,, 223, 263, 359, and474 nm is also characteristic of the phenoxazonesystem.6 On only this evidence a choice between theseisomers is not possible, though the substitution patternof the second (16) is hard to reconcile with that of theoriginal aniline (1).But QIm:;: 0 0(16 1Phenoxazones are hydrolysed in mild alkali to 2-hydroxy-N- (2-hydroxyphenyl) -$-benzoquinone imines, areaction which is instantly reversed by a ~ i d . ~ ~ ~ Thisproperty suggested a possible method for the chemicalcharacterisation of the product, for if the ring-openingreaction was conducted in methanol with potassiummethoxide, a possible pathway to a readily accessibleN-phenyl-quinone imine (12) would be manifested(Scheme 2).Consideration of the method of preparation0of phenoxazones from o-aminophenols and hydroxy-or methoxy-quinones suggested that isolation andindependent synthesis of the intermediate quinone iminederived from (17) would be difficult, and the subsequentmethylation step was therefore included. The reactionshould thus yield (12) from ($9, or the isomer if thephenoxazone were (16). Unfortunately, only a smallquantity of dark brown gum was obtained, but thisexhibited the same behaviour on t.1.c. as the syntheticquinone imine (12). This material and its isomer werereadily prepared by acid-catalysed condensation of2-met hoxy-5- t -but yl-$-benzoquinone with 2,5-di-methoxy-4-t-butylaniline (1) and 2,4-dimethoxy-5-t-butylaniline, respectively.The phenoxazone was there-fore considered to have structure (8), and this wasconfirmed by the synthesis to be described in Part 111.DISCUSSIONAs was shown by t.l.c., the phenazine (3) was presentin both oxidations of (1) prior to chromatography, andthus the di-imine ( l l ) , which must be intermediate in itsformation, is able to undergo cyclisation at room tem-perature. The suggested sequence of reactions leadingto the phenazine is shown in Scheme 3. This reactioncontrasts with the behaviour of the dimethoxy-analogueof (1 1) .l Thus, the presence of the ortho-methoxy-groupon the phenyl portion of (11) greatly facilitates cyclis-ation.This has already been noted in connection withthe oxidation of similarly substituted 2-anilinoaniline~,~and is apparently a consequence of the ease of elimin-ation of an alcohol or a hydrogen halide, resulting in thedirect production of an aromatic system. Where nosuitable leaving group is present, the immediate resultof such a cyclisation is merely a dihydro-compound. Amajor factor influencing the cyclisation of compounds-MeOH ISCHEME 3such as (1 1) may be electron release by the ortho-methoxy-group and this would certainly be so in an acid-catalysedreaction.The di-imine (1 1) is also considered to be the precursorof compound (5) and of the quinone imine (6). Form-ation of the latter is easily explained as the result ofaddition of water to the di-imine (11) followed by loss ofmethanol.Compound (5) was only obtained from theferricyanide oxidation, and this is ascribed to thepresence of unchanged aniline (1) , which could condenseeither with any of the quinone imine (10) that may havebeen produced in the oxidation, or with the di-imine (11)as shown in Scheme 4. In connection with the lattersuggestion, if cyclisation of (20) occurs in the alternative5 J. F. Corbett, Spectrochim. Acta, 1965, 21, 1411.6 W. Schafer, Progr. Org. Chem., 1964, 6, 135.7 W. Sch2ifer and H. Schlude, Tetrahedron Letters, 1968, 21611972 41 1sense to give (21), in which the quaternary methoxy-group is not conjugated with any other methoxy-group,a second condensation with the aniline (1) will notproduce compound (5).A rI OMeBut a I , D B " tMe0 / OMe(27 1I OMeArH+ -MeOH 1 Me0 O O M e /But(20)A rAr = 2,4-(OMe),-4-ButC,H,SCHEME 4The only obvious precursor of the phenoxazone (8)appears to be the N-phenyl-o-quinone imine (22), whichwould result from hydrolysis of the di-imine (11).Thesuggested reaction sequence is shown in Scheme 5.H+l I-.+ItOMe 2Ring closure of compounds such as (23), resulting fromcondensation of o-aminophenols with hydroxy- 6 ormethoxy-quinones to the hemiacetal (24), is formallyanalogous. The possibility of further hydrolysis of theo-quinone imine (22) to the $-quinone imine (25) andcyclisation of the latter to the phenoxazone must also beconsidered, but the failure of the amino-quinone imine(6) to cyclise under the conditions of its isolationindicates that this is an unlikely pathway.H H(23) ( 2 4 ) OHThe formation of the amino-quinone imine (4) duringchromatography of the ferricyanide oxidation productsparallels the formation of the related compound from3-metho~y-4-t-butylaniline.~ The suggested sequence isshown in Scheme 6, and again invokes preliminary paracarbon-nitrogen coupling, followed by rearrangement ofNHH+? NH" 2 0- 2MeOHAr = 2,5-(OMe) ,-4-ButC,H,SCHEME 6the iminocyclohexadiene (26) so produced.Whereasoxidation was subsequent to the hydration of thecarbonium ion in the formation of the related compoundfrom the monomethoxy-analogue, elimination ofmethanol is all that is required in the present case.The isolation of the debutylated quinone imine (7)substantiates the assumptions made in both this and theprevious paper concerning the involvement of imino-cyclohexadienes e.g.(26). The least obscure pathwayto ( 7 ) is shown in Scheme 7, and involves a type ofdebutylation for which there is ample precedent 899 in* T. Matsuura and H. J. Cahnmann, J. Amer. Chew. SOC.,1960, 82, 2055.9 .C. J. R. Adderley and F. R. Hewgill, J . Chem. SOC. (C),1968, 1438. SCHEME 412 J.C.S. Perkin Ithe reactions of aryloxycyclohexadienones produced bythe oxidative coupling of phenols.OH0 x.( 7 ) Me0NHAr+Me,C*Ar = 2,5-(OMe),-4-ButC6H,SCHEME 7EXPERIMENTALGeneral details were as described in the previous paper.lLight petroleum had b.p.56-60". 2,5-Dimethoxy-4-t-butylaniline (l), m.p. 8A85° (1it.,lo 84-85") was preparedas previously described. Its acetate crystallised as needles,m.p. 137.5-138.5" (from ether-light petroleum) (Found : C,66.7; H, 8.35.Oxidation of 2,5-Dimethoxy-4-t-butylaniline (1) .--(.a) Bypotassium ferricyanide. The aniline (6.28 g) and oxidant(21.7 g) were treated as described for 3-methoxy-4-t-butyl-aniline,l and gave a dark crystalline residue. Removal ofmaterial soluble in light petroleum left 2,2', 5,5'-tetra-~nethoxy-4,4'-di-t-butylazobenzene (2) (640 mg) as orangeplates, m.p. 243-245" (from chloroform-ether) (Found : C,69.3; H, 8.3; N, 7.0. C,,H,,N,O, requires C, 69.5; H,8.3; N, 6-8), Amaxe (CHC1,) 263, 328, 428, and 463sh nm(log E 3.88, 3-73, 3-84, and 3-81), 7 (CDCl,) 2.72 (2 x ArH),3.01 (2 x ArH), 5.96 (2 x OMe), 6-08 (2 x OMe), and8.60 (2 x But).Chromatography of the light petroleumextract on alumina gave five fractions.Fraction (i), eluted with light petroleum-ether (1 : 0 to4 : 1), contained 3,8-dimethoxy-2,7-di-t-butylphenazine (3)(532 mg), m.p. and mixed m.p. 204-205", and a smallamount of the azobenzene (2).Fraction (ii), eluted with light petroleum-ether (7 : 3 to1 : 1) gave material which had a red fluorescence on t.1.c.plates under U.V. light. This was rechromatographed onsilicic acid. Elution with light petroleum-ether (1 9 : 1) gave8-methoxy-2,7-di-t-butyl-3H-fihenoxazin-3-one (8) (1 20 mg) asred needles, m.p. 124-126" (from light petroleum) (Found:C, 74.35; H, 7.4; N, 4-45.C21H25NO3 requires C, 74.3; H,7.4; N, 4*1y0), vmaX. 1641m and 1613s cm-1, A,,,. (cyclo-hexane) 223, 263, 282sh, 346sh, 359, and 474 nm (log E 4.13,4-05, 3.51, 3.99, 4.03, and 4.19), 7 (CCl,) 2.87 (2H), 2-94 and3.98 (ZH), 6.07 (OMe), and 8.59 and 8.62 (2 x But). Rapidwork was necessary during isolation of this material as itdecomposed on chromatographic adsorbents to a red gum,which contained no methoxy-substituent (n.m.r.) .Fraction (iii), eluted with light petroleum-ether (1 : l),deposited the aniline (1) from n-pentane. The motherliquors were chromatographed on silic acid. Elution withlight petroleum-ether (7 : 3) gave a brownish red material,ClgH2103 requires C, 66.9; H, 8.4).which was purified by preparative t.1.c.on alumina inbenzene-hexane ( 1 : 1) to give 2-amino-4- (2,5-dimethoxy-4-t-butyl~henylimino)-5-t-butyEcyclohexa-2,5-dien-l-one (4)(30 mg) as a brownish red gum, vmx. 3496m, 3388m, 1661s,and 1631s cm-l, 7 (CDC1,) 3-06 and 3.78 (2 x ArH), 3.47and 4-19 (2 vinylic H), 5.67br (NH,), 6-23 and 6-30 (2 xOMe), and 8.53 and 8.60 (2 x But).Fraction (iv), eluted with ether, deposited crystals (1.88 g)of the aniline (1) from light petroleum. Chromatographyof the mother liquors on alumina and elution with lightpetroleum-ether (9 : 1) gave lO,N-bis-(2,5-dimethoxy-4-t-butylpheny 1) -7-nzethoxy- 3,8-di-t-butyl- 1OH-phenazin-2-kine(5) (109 mg) as blue needles, m.p. 182-183" (from lightpetroleum) (Found: C, 75.0; H, 8-5; N, 5.55.C,5H,gN,0,requires C, 75.0; H, 8-2; N, 5-8), A,, (cyclohexane) 227,307, and 570 nm (log E 3.90, 3.79, and 4-09), T (CC1,) 2.87,2.92, 3-11, 3-75, 3.91, and 4-92 (6H), 3.41 (2H), 6.07, 6.32,6.37, 6.49, and 6-56 (5 x OMe), and 8-45, 8-63, 8-72, andFraction (v), eluted with ether-chloroform (1 : 0 to 7 : 3)was separated from the aniline (1) and dark colouredmaterials by fractional crystallisation from light petroleum-ether. The first crops gave 4-( 2,5-dimethoxy-4-t-butyl-~henylimino)-2,5-dimethoxycyclohexa-2,5-dien-l-one (7) (10mg) as pink needles, m.p. 207-209" (from ether-chloroform)(Found: C, 66.4; H, 7.15; N, 4.05. C,,H,,NO, requiresC, 66.8; H, 7.0; N, 3-9), vmx. 1652s cm-l, A,, (cyclo-hexane) 213, 298, and 487 nm (log E 4.29, 4.36, and 3-43),(CDC1,) 3-07 and 3-54 (2 x ArH), 4.09 (2 vinylic H), 6.08,6.23, 6.26, and 6.34 (4 x OMe), and 8.60 (But).T.1.c.of a light petroleum solution of the oxidationproduct prior to chromatographic separation showed thephenazine (3) and the azobenzene (2) only. Yields ofcompounds (5) and (8) were variable.(b) By silver oxide. The aniline (1) (6.28 g) was oxidised bysilver oxide (16 g) in ether as described for 3-methoxy-4-t-buty1aniline.l The dark crystalline residue was fractionatedas in (a) to give the azobenzene (2) (860 mg), the phenazine(3) (1.97 g), the phenoxazone (8) (18 mg), and the quinoneimine (7) (27 mg). In addition to these products, ether-chloroform (7 : 3) eluted material which was rechromato-graphed on alumina, and crystallised from ether-lightpetroleum as red needles (7 mg), m.p.147.5-148-5", of5-amino-4- ( 2,5-dinzethoxy-4-t-butylphenylimino) -2-t-butyl-cyclohexa-2,5-dien-l-one (6) (Found: C, 71.4; H, 8.1; N,7.6. C,,H,,N,O, requires C, 71.3; H, 8.2; N, 7.6y0),v,=. 3497m, 3374m, 1646m, and 1623s cm-l, A,, (cyclo-hexane) 221, 296, and 470 nm (log E 4.26, 4.26, and 3.54),7 (CDC1,) 3-06 and 3.58 (2 x ArH), 3.42 and 4.34 (2 vinylicH), 4-73br (NH,), 4.20 and 4.23 (2 x OMe), and 8-58 and8.78 (2 x But).T.1.c. prior to chromatographic separation of the oxidationproducts showed that the quinonoid products were formedduring chromatography. None of the unchanged aniline(1) or the blue compound (5) could be detected. 4-Methoxy-5-t-butyl-1,2-benzoquinone was not formed ineither oxidation.2,2',5,5'-Tetramethoxy-4,4'-di-t-butylazobenzene (3) .-2,5-Dimethoxy-4-t-butylaniline (1) (210 mg) was diazotised inacetic acid and coupled with 4-methoxy-3-t-butylphenol.The resultant 2-hydroxy-2',5,5'-trimethoxy-4,4'-di-t-butylazo-benzene (340 mg) crystallised as red-brown plates, m.p.254-256" (from chloroform-ether) (Found: C, 68.6; H,8-81 (4 X But).10 F.R. Hewgill, J . Chem. SOG., 1962, 49871972 4138.35. C,,H,,N,O, requires C, 69.0; H, 8.05y0), T (CDCl,)2.61, 2.68, 2.99 and 3.11 (4 x ArH), 5.97 (OMe), 6.02(2 x OMe), and 8.57 and 8.58 (2 x But). With dimethylsulphate and potassium carbonate in refluxing acetoneduring 18 h, the azophenol gave a tetramethoxyazobenzeneidentical with compound (2).Condensation of 2,5-0imethoxy-4-t-butylaniline (1) .-(a) With 6-imino-4-methoxy-3-t-butylcycEohexa-2,4-dien-l-one(9). The o-quinone imine (9) from the parent amino-phenol (390 mg) was heated with the aniline (1) (400 mg)in acetic acid on a steam-bath for 3 min.Addition of waterand extraction of the product with ether gave a deep redresidue which deposited red needles (160 mg) from lightpetroleum. Recrystallisation from chloroform-ether gave2- (2,5-dimethoxy-4-t-butylanilino) -4- (2,5-dimethoxy-Ct-butyI-~henylimino)-5-t-butylcyclohexa-2,5-dien-l-one (lo), m.p.225-227" (Found: C, 72.2; H, 8.2; N, 5.0. C,,H,,N,O,requires C, 72.6; H, 8.2; N, 5.0), vmX. 3316m, 1653s, and1628s cm-l, T (CDC1,) 2.47br (NH), 3.10, 3.20, 3-52, and 3.71(4H), 3.36 (2H), 6-18, 6.26, 6.31, and 6.56 (4 x OMe), and8.49, 8.60, and 8-68 (3 x But).Concentration of the light petroleum mother liquors gaveunidentified orange-yellow crystals (54 mg) which de-composed a t ca.230" to a blue liquid. Chromatography ofthe residual mother liquors on alumina and elution withlight petroleum-ether (1 : 0 to 4 : 1) gave material whichwas separated by preparative t.1.c. on silica gel in methanol-benzene (3 : 2) into two fractions. The first of thesedeposited crystals (8 mg) of 3,8-dimethoxy-2,7-di-t-butyl-phenazine (3), m.p. and mixed m.p. 204-205O (from lightpetroleum). The second fraction gave unidentified paleyellow needles (20 mg), m.p. 181-182". More polarsolvents eluted small amounts of the anilino-quinone imine(lo), and then a deep brown gum (30 mg), identified as theamino-quinone imine (4) by i.r.spectroscopy after pre-parative t.1.c.(b) With the amino-quinone imine (4) and the anilino-quinone itnine (10). Reaction of the amino-quinone imine(4) with the aniline (1) in acetic acid during 7 h, dilutionwith water, and extraction with ether gave the anilino-quinone imine (10). The latter (10 mg) when treated withan excess of the aniline (1) in acetic acid during 6 h gave ablue product (3 mg) identical with the oxidation product(5) of the aniline (1).(c) W-ith 2-amino-5-t-butyl-1,4-benzoquinone. Reaction ofthe aniline (1) (209 mg) with this quinone (179 nig) in aceticacid for 5 h on a steam-bath gave a dark red solution. Thiswas diluted with water and extracted with ether; theextract was evaporated and the residue was chroniato-graphed on alumina.Elution with light petroleuni-ether(1 : 0 to 4 : 1) gave the unchanged quinone (80 mg). Ethereluted material (60 mg) identical with the amino-quinoneimine (6) obtained from the oxidation of the aniline (1).(d) With 2,5-dimethoxy- 1,4-benzoquinone, A solution ofthe aniline (1) (627 mg) and this quinone (504 mg) in aceticacid (30 ml) was heated on a steani-bath for 30 min. Thepurple solution was poured into water and the crystallineprecipitate was filtered off and extracted with boiling etherto leave a residue of unchanged quinone. The extract wasevaporated and the residue was fractionally crystallisedfrom ether-light petroleum to give first 5- (or 2)-methoxy-2-(or 5)-2,5-dimethoxy-4-t-butylanilino)-4-( 2,5-dimethoxy-4-t-butylphenylimino)cyclohexa-2,5-dien-l-one ( 14) or (15)(200 mg) as purple prisms, m.p.212-214' (Found: C,68-9; H, 7.6; N, 5.6. Calc. for C,,H,,N,O,: C, 69.4; H,7-5; N, 5.2), vrnZ 3307s, 1649s, and 1629m cm-l, T (CDC1,)3-15, 3-18, 3.33, 3.56, 3-73, and 4-03 (6H), 6.04, 6-20, and6.53 (3 x OMe), 6-28 (2 x OMe), and 8.62 and 8.69 (2 xBut). The more soluble component was 5-( 2,5-dimethoxy-4-t-butylanilino)-2-nzethoxy-l,4-benzoquinone (13), obtainedas purple needles (201 mg), m.p. 149-150" (Found: C,66.3; H, 6.9; N, 4.4. C19H,,N05 requires C, 86.1; H, 6.7;N, 4.1y0), v,, 3320m, 1662s, and 1647sh cni-l, T (CDCl,)2.02 (NH), 3.08 and 3-10 (2 x ArH), 3.89 and 4-13 (2vinylic H), 6.13 (2 x OMe), 6-18 (OMe), and 8.61 (But).T.1.c.of the mother liquors showed the presence of un-changed aniline (l), but not of the quinone imine (7).(e) With 4- (2,5-dimethoxy-4-t-butyl~henyZin~i~zo) -2,5-di-11aethoxycyclohexa-2,5-dien- l-one (7). Addition of the aniline(1) (4 mg) in acetic acid (1-5 ml) to the quinone imine (7)(7 mg) in acetic acid (1.5 ml) at room temperature gave adeep blue solution. After 15 min this was poured intowater. Extraction with ether and evaporation of theextract gave a purple residue, which was recrystallised fromether-light petroleum to give material (7 mg) identical with(14) or (15) obtained in (d).(f) With B-methoxy-2-t-butyl-l,4-benzoquinone. Equi-molar solutions of the aniline (1) and the quinone in aceticacid were mixed and heated on a steam-bath for 15 min.The cooled solution was poured into water and extractedwith ether.Evaporation of the extract and recrystallisationof the residue from ether-light petroleum gave 4-(2,5-dimethoxy-4-t-butylphenylimino) -5-methoxy- S-t-butylcyclo-hexa-2,5-dien-l-one (12) as dark reddish brown prisms,m.p. 108-109-5° (Found: C, 71.55; H, 7.8; N, 3.6.C,,H,,NO, requires C, 71.7; H, 8.1; N, 3.6y0), vmX1635s cm-l, A,, (cyclohexane) 218, 294, and 510 nm (log E4.04, 4.22, and 3*43), T (CDCl,) 3.14, 3.47, and 3.62 (3H),4-30 (vinylic H), 6.20, 6-22, and 6.30 (3 x OllIe), and 8.62and 8.82 (2 x But).Reactions of 8-Methoxy-2,7-di-t-butyl-3H-phenoxazin-3-one(8) .-(a) Reductive acetylation. With zinc dust and sodiumacetate in gently refluxing acetic anhydride the phenoxazone(8) gave, after 10 min, S-acetoxy-lO-acetyZ-8-methoxy-2,7-di-t-butylphenoxazine, needles, softening a t 94-100" to a viscousliquid (Found: C, 70.9; H, 7-5; N, 3-1. C,,H,,NO,requires C, 70-6; H, 7.3; N, 3.3), vrnax. 1766s and 1691scm-l, T (CC1,) 2-62, 2.99, 3.04, and 3.25 (4 x ArH), 6.17(OMe), 7.67 (2 x COiLle), and 8.65 (2 x But).(b) Methylation. The phenoxazone (8) (66 mg) washeated under gentle reflux for 4 h in dry methanol (14 ml)containing potassium methoxide (90 mg) . The resultingdeep blue mixture was cooled to O", then potassium car-bonate (3 g) was added, followed by dimethyl sulphate,dropwise, until the evolution of carbon dioxide ceased. Afurther quantity (70 mg) of dimethyl sulphate was thenadded, and the mixture was heated under reflux for 5 h.After filtration the solution was evaporated to drynessunder reduced pressure, leaving a brown gum. Applicationof this to alumina and elution with light petroleum-ether(7 : 3) gave ca. 3 mg of a brown-purple gum. This couldnot be purified without considerable loss, but the RF values(t.1.c.) were identical with those of the quinone imine (12).We thank General Motor's-Holden Pty. Ltd. for a Fellow-ship (to R. K. H.), and the Australian Research GrantsCommittee for financial assistance.1/1499 Received, August 18th, 1971