Preparation and dimerisation of 2-phenylinden-1-one

摘要

1974 2617Preparation and Dimerisation of 2-Phenylinden-1 -oneBy Philip H. Lacy and Donald C. C. Smith, Chemistry Department, The University, Manchester M13 9PLThe preparation of 2-phenylindenone and its conversion into truxone-type photodimers (the tetrahydrocyclobuta-di-indenediones (6) and (7) and a Diels-Alder-type dimer (the tetrahydrobenzaindeno2,1 -cfluorene-5,10-dione (5)) are described.THE red diketone (l), whiclr has been the subject of anX-ray structural determination,l is obtained in place ofthe expected 2-phenylinden-1-one (2) in the cyclisation of2-phenylcinnamoyl chloride,l in the pyrolysis or base-induced dehydrobromination of 2-bromo-2-phenylindan-1-one, and from oxidation of 1-bromo-2-phenylindenewith dimethyl sulphoxide.2 2-Phenylinden-1-one (2),hitherto known only as its oxime prepared directly from~henylindene,~ could not be obtained by an otherwiseflexible synthesis of in den one^.^Reduction of the indane-1,3-dione, a route used toprepare inden~ne,~ has now been adapted for the prepar-ation of 2-phenylinden-1-one.Reduction of 2-phenyl-indane-l,3-dione with zinc and acetic acid gave twostereoisomeric hydroxy-ketones (3) and (a), from whichthe former (3) was isolated. Repetition of an earlierhydrogenation of 2-~henylindane-l,3-dione,~ yielded theisomer (4). The hydroxy-ketones (3) and (4) are readilydehydrated to 2-phenylinden-1-one by boiling briefly indilute methanolic hydrochloric acid, but when high con-centrations of hydroxy-ketones are used the dimer (5) isthe main product.Dehydration in acid of the hydroxy-ketones (3) and (4) contrasts with the behaviour ofindenone itself, which adds water or other solvents in thepresence of acid.52-Phenylinden-1-one is an orange crystalline ketonethat yields colourless, less soluble products during re-crystallisation ; however a boiling dilute solution in car-bon tetrachloride is stable for 24 h in the absence of light.In daylight colourless crystals are deposited, and we haveisolated three of the four possible truxone-type photo-dimers (6) and (7) with either syn- or anti-configurationabout the central ring.Conversion of 8-phenylinden-1-one into the dimer (5)takes place readily in acidic solutions : in trifluoroaceticacid, the dimer (5) is the only product and the dimeris-ation is complete within 15 min at room temperature.It was identified from its reactions and its spectra.It isdehydrogenated to the diketone (1) by selenium dioxide,it has three non-aromatic protons, one exchangeable inalkali, and it is acidic enough to give reversibly an orangesalt (8) even with ammonia (this can be used for locating iton thin-layer plates). Its U.V. spectrum shows a largeshift in alkali, almost identical with that exhibited by 2-l A. L. Bednowitz, W. C. Hamilton, 13. Brown, L. G. Dona-ruma, P. L. Southwick, R. Kropf, and R. A. Stanfield, J . A w w .Client. SOC., 1968, 90, 991.S . Wawzonek, G. H. Hanscn, and A. R. Zigman, Chew.Coritvn., 1969, 6.E. Bergmann and W. Schruibcr, Bey., 1933, 68, 44.31.B. Floyd and G. R. ibsol;llcn, J . Org. Clzent., 1970, 35, 2647.I-rsquo;. H. Lacyand D. C. C. Smith, J . Chem. SOC. (C), 1971,41.T. T. Dumpis and G. Vanags, Doklady Akad. Naztk S.S.S.R.,1962, 142, 92.phenylindan-1-one except that the absorption of thelatter does not have a shoulder in the visible region;HO-.(10)HOI 4 1amp; H H amp; lsquo; H H(8) R = 0- M+19) R = O A C(11)benzyl phenyl ketone gives a similar anion spectrum butonly in more concentrated alkali. Acetate-catalysedacetvlation of the dimer (5) leads to the acetate (10). bu2618 J.C.S. Perkin Iin the presence of sufficient acetic acid the reaction stopsat the enol acetate stage (9), presumably because in asufficiently protic medium, acetate anion is not basicenough to promote the prototropic rearrangementThe stereochemistry of the dimer (5) throws lighton the mechanism of dimerisation of 2-phenylinden-l-one in acidic solutions.The dimer (5) and its enolacetate (9) presumably have the same cis-5a,l4c-configuration as the diketone (1).1 The dimer (5) andits enol acetate (9) both have a distinctive one-protonn.m.r. signal, at 'C 4.9 and 3.9, respectively, and spindecoupling identifies these as due to aromatic protons,since each shows vicinal coupling with protons resonatingin the aromatic region, at 'C 3.0 and 2.6, respectively.Protons close to and axial to an aromatic ring are shieldedby it, and models reveal this to be so for a proton a tposition 1 or 14 depending on which way the molecule istwisted, provided that the 5a,14c and 9b,14b ring junc-tions are in a syn-relationship, as shown in the formulae(5) and (9).The cis,syn,cis-configuration thus derived for the dimer(5) shows that the dimerisation of 2-phenylinden-l-oneis not only stereospecific, as are most Diels-Alder reac-tions, but that it also obeys Alder's endo rule.' This isconsistent with a concerted cycloaddition mechanism ,and the presumed initial product of addition, between 2-phenylinden-l-one acting as a diene and its conjugateacid acting as a dienophile, is the species (11) , which canisomerise into the dimer (5) via the enol or the enolate (8)without disturbing the syn-configuration of the centralring.(9) * (10).EXPERIMENTALtrans-3-Hydroxy-Z-phenylindan- l-one (3) .-2-Phenylin-dane- 1,3-dione (from benzylidenephthalide,8 by isomeris-ation with sodium methoxide g, (2 g) and acetic acid (50 ml)were warmed to give a clear solution, then stirred a t 40" aszinc powder (5 g) was added.The temperature rose to 50"and the reaction then subsided. The mixture was stirredfor 0-5 h, then filtered, and the solids were washed withacetic acid. Filtrate and washings were combined, con-centrated in zlacuo below 50", and diluted with ethyl acetate.The solution was washed with aqueous sodium hydrogencarbonate, dried (MgSO,) , and concentrated. Redissolu-tion in carbon tetrachloride followed by concentration(twice) afforded a pale yellow glass (2.2 g). N.m.r. spectro-scopy showed this to consist of the epimeric hydroxy-ketones (3) and (4).Chromatography on silica gave 2-phenylindenone (2) (0.05 g) (eluted with benzene) and trans-3-hydroxy-2-phenylindan-l-one (3) (1.73 g) eluted with ethylacetate-benzene (1 : 9) as yellowish crystals, m.p. 85-87'(Found: C, 80.1; H, 5.5. C1,H1,O, requires C, 80.3; H,5.4) ; vmx. (CHC1,) 3600, 3450, 1720, and 1610 cm-1; hx(MeOH) 244, 283, 290, and 315sh nm (log E 4-02, 3.29, 3.29,and 2.65); T (CDCl,) 2.3-3.1 (9H, m), 4.9br (lH, sharpen-ing after D,O exchange to d, J 4 Hz), 6.lbr (lH, s, exchange-able in D,O), and 6.5 (lH, d, J 4 Hz); in/e 224 (Mf, 98)and 178 (100).cis-3-Hydroxy-2-phenylindan- 1-one (4) .-2-Phenylindane-1,3-dione (1.12 g) in ethyl acetate was hydrogenated overpalladium-charcoal at atmospheric pressure for 1.5 h; theorange colour of the dione was discharged in half this time,and uptake of hydrogen reached 255 ml.Removal of thesolid and concentration gave colourless prisms (from carbontetrachloride) (201 mg) (m.p. 115-120"; cf. ref. 6); 7(CDCI,) 2.1-3.0 (9H, m), 4-5br (lH, sharpening after D,Oexchange to d, J 7 Hz), 5.9 (lH, d, J 7 Hz), and 8.lbr (lH, s,exchangeable in D,O) .The doublets ( J 4 and 7 Hz) in the spectra of compounds(3) and (4) are attributed to these isomers respectively byanalogy with Jtmm and Jeis of indanone (respectively 3.49and 8.65 Hz).1deg;2-Phenylinden- 1-one (2) .-3-Hydroxy-2-phenylindan- 1-one (100 mg) in boiling methanol (10 ml) was treated withconcentrated hydrochloric acid (0.5 ml) and boiled underreflux for 20 min.The solution was then concentrated invacuo and extracted with ethyl acetate. The extract waswashed with sodium hydrogen carbonate solution, dried(Na,SO,), and concentrated to an orange oil. This waschromatographed on a short column of silica gel (benzene aseluant) to give 2-phenylinden- l-one as orange prisms (62mg), m.p. 75-76". Recrystallisation from petroleum (b.p.60-80deg;) resulted in losses due to formation of insoluble sub-stances, but gave a product of m.p. 81-83" (Found : C, 87-1 ;H, 4-6. Cl,H,,O requires C, 87.4; H, 4.8) ; vmX. (CHCl,)1715 and 1605 cm-l; (MeOH) 261, 275sh, 300sh, and430 nm (log c 4.51, 4.32, 3.24, and 3.24) ; T (CDCl,) 2.2-3-1(m); m/e 206 (loo), 178 (31), 176 (21), and 152 ( l l ) , m*153.5 (206 ---t 178), and 129.5 (178 -+ 152).Carried outon a larger scale, this dehydration gave proportionately less2-phenylindenone.5a, 9b, 14b, 14c-Tetrahydro-5a-phenyZbenzaiszdeno 2, 1-cJ-fluorene-5,lO-dione ( 5 ) .-(a) 2-Phenylinden- l-one (395 mg) intrifluoroacetic acid (20 ml) gave a clear deep red solutionwhose colour faded. After 15 min, t.1.c. and n.m.r. spectro-scopy showed that only compound (5) was present. Con-centrated in vmuo and recrystallisation from benzene-chloroform gave colourless prisms, m.p. 272-282', decom-posing to an orange melt (Found: C, 87.1; H, 4.8. C,,H,,O,requires C, 87.3; H, 4.9) ; vmax. (CS,) 1730 and 1720 cm-l; hx. (EtOH) 245, 299, 319, and 355sh nm (log E 4.38, 4-02,4-09, and 3.58) ; (ethanolic O.~N-KOH) 246, 293sh, 362,and 450sh nm (log E 4.30, 4.02, 4.24, and 3.56); T (CDCl,)2.0-3.1 (16H, m), 4.9 (lH, d, J 7 Hz, collapsing to s onirradiation a t T 2-96), and 5.7-6.1 (3H , m , collapsing to 2H,s a t T 5.9 with NaOD in D,O) ; m/e 412 (M+, loo), 394 (25),307 (12), 294 (12), and 206 (12); m* 376.8 (412- 394),239 (394 --+ 307), and 210 (412 --t 294).(b) 3-Hydroxy-2-phenylindan- 1-one (6.4 g) in methanol(60 ml) and concentrated hydrochloric acid (3 ml) was boiledunder reflux; solid separated and after 20 min this wascollected, washed with methanol, and dried (3-3 g).Tworecrystallisations from benzene-chloroform gave the dimerPhotodiwrs from 2-Phenylinden-l-one.-2-Phenylinden-l-one (398 mg) in ethanol-free chloroform (2 ml) was exposedto full daylight in a narrow tube for 1 week, during which timelarge colourless crystals were deposited.These were col-( 5 ) (1.4 euro;4.' H. Wollweber in ' Methoden der Organischen Chemie 9 F. Nathanson, Ber., 1893, 26, 2576.* R. Weiss, Org. Synth., 1933, 13, 10.(Houben-Weil),' Thieme Verlag, Stuttgart, 1970, p. 789. l o S. Forsen, B. Gestblom, R. A. Hoffman, and S. Rodmar, J .ilfol. Spectroscopy, 1966, 21, 3721974 2619lected, washed with carbon tetrachloride, and dried (197mg). The filtrate was concentrated t o a fluffed glass. Bothproducts were separated into their constituents by prepara-tive t.1.c. on silica, developed with benzene. The crystalscontained only the truxones A and B (see Table); thefiltrate, as well as yielding more of these, contained thetruxone C, some 2-phenylinden-l-one, some of the red di-ketone ( l ) , and an unidentified compound, C,,H1,03, m.p.328-330" (6 yield). Truxones A--C all had similar massspectra: m/e 412 (M+, 0.5y0) and 206 (100).Photodimers (tetrahydrodiphenylcyclobutadi-indenediones)from 2-phenylinden-l-oneVmeX.1 'FRF cm-1 (CDCI,) Found * YieldTruxone (C,H,) 3l.p.("C) (CHC1,) (2Hs) C H yoA 0.48 339-340 1706 5.26 87.4 4.9 40B 0.24 317-320 1705 5.37 87.5 4.9 26C 0.16 230-232 1715 5.14 87.7 4.9 12* C3,H2,O2 requires C, 87.3; H, 4.9.Dehydrogenation of the Dinzer (5) .-The dimer ( 5 ) (99 mg)and selenium dioxide (54 mg) were boiled under reflux for3 h in benzene (20 ml) and 2-methylpropan-2-01 (20 ml), thecolour gradually becoming deep orange.Removal of thesolvents in vacuo left a crystalline residue that was resolvedon a preparative silica thin-layer plate (20 x 20 x 0.2 cm)developed with chloroform. The orange zone of R p 0.5yielded a red solid, still smelling of selenium (105 mg) . Thiswas triturated with acetone and drained giving 5a,14c-dihydro-5a-phenylbenzaindeno2,l-cfluorene-5,l0-dione(1) (69 mg) as red prisms, m.p. and mixed m.p.l 264-266",v,, (CS,) 1718 cm-l; 15: (CDC1,) 1.6 (lH, q), 1-9-3.1 (16H,m), and 5.3 (lH, s); m/e 410 (100).A ZkaZi Shifts in Absorption Spectra.-(a) 2-Phenylindan- 1-one: l1 Amx. (EtOH) 245, 286sh, 294, and 325sh nm (log E4.07, 3.40, 3.43, and 2.86); kx (ethanolic 0-hi-KOH) 359nm (log E 4.13) ; z (CD,OD) 2.0-3.0 (9H, m), 5.9-7-0 (3H,m); T (NaOD in CD,OD) 2-0 (2H, d, J 7 Hz), 2.3-3.1 (7H,m), and 6.6 (2H, s) .(b) Benzyl phenyl ketone: l2 A,, (EtOH) 243, 280sh, and325sh nm (log E 4.13, 3.18, and 2.81) ; LX (ethanolic 27KOH) 347 nm (log E 3.99).10-A cetoxy- 10,14c-dihydro-5a-phenyZbenzaindeno2,l-c-fluoren-5(5aH)-one( lo).-The dimer (5) (1 11 mg) and potas-sium acetate (50 mg) were boiled under reflux for 1 h ina.cetic anhydride (10 ml).The mixture was diluted withethyl acetate, washed with water, then concentrated in vacuoto a glass that was resolved on a preparative silica thin-layerplate (20 x 20 x 0-2 cm) developed twice with benzene.The zone fluorescing yellow in near U.V. light (RF 0.3) yieldeda glass (127 mg) that was recrystallised from acetone-hexanegiving compound (10) (63 mg), probably a mixture of 10-epimers, as small cream needles, m.p. 187-249" (Found:C, 84.3; H, 5.0.C,,H,,O, requires C, 84-6; H, 4.9);vmxs (CS,) 1742, 1720, and 1232 cm-l; Amx. 243, 250sh,294sh, 313sh, 326sh, 335, and 354sh nm (log E 4.47, 4.40,3.95, 4.07, 4.13, 4.15, and 3.96); T (CDCl,) 2-0-3.2 (18H,m), 5-3 (lH, s), and 7-8 (3H, s); m/e 454 (M+, 79), 412(26), 411 (79), 410 (37), 394 (63), 393 (loo), and 289 (53), m*373.8 (454- 412) and 342 (454- 394).10-A cetoxy- 14b, 14c-dihydro-5a-phenyIbenzaindeno2,l-c-fEuoren-5(5aH)-one (9).-The dimer (5) (140 mg) and aceticanhydride (20 ml) were boiled under reflux while aqueous10 sodium acetate (0.5 ml) was added dropwise, thenboiled for 0.5 h. The mixture was diluted with ethyl acetate,washed with water, then concentrated in vacuo t o a glassthat was chromatographed on a preparative silica thin-layer plate (20 x 20 x 0.2 cm) developed four times withbenzene. The zone fluorescing blue in near-u.v. light ( R p0.2) yielded crystals (99 mg) which afforded colourlessprisms (65 mg), m.p. 285-286" (from carbon tetrachloride)(recrystallised again from benzene for analysis) (Found :C, 84.5; H, 4.9. C,,H,,O, requires C, 84-3; euro;3, 4.9);v,, (CS,) 1777, 1718, and 1192 cm-l; hrnx (EtOH) 241,256sh, 290, 301, 313, and 352sh nm (log E 4.37, 4.29, 4.23,4.25, 4.27, and 3.65); z (CDCl,) 2.1-3-0 (16H, m), 3.9br(lH, dd, collapsing to s on irradiation a t z 2.6), 5.75 (lH, d,J 5 Hz), 5.9 (lH, d, J 5 Hz), and 7.7 (3H, s); m/e 454 (M+,16), 412 (loo), and 394 (55), m* 373-8 (454- 412).scholarship (to P. H. L.).We thank the University of Manchester for a research4/1616 Received, 22nd July, 19741l1 P. C. Jocelyn, J . Chem. Soc.. 1954, 1640.l2 C. F. H. Allen and W. E. Barker, Org. Synfh., 1932, 12, 16