An intramolecular chloroalkylation reaction

'Ietrahedron Letters No.22, pp. 1889-1892, 1970.

ANIIimAMoby&

Pergamon Press.

cElnmO-TIoH

P. Steveno

Printed in Great Britain.

ruAcTI(wI

and F.Rasura

~trgm=t=nt American UniYerI3ity

of Beirut

Beirut,Ldxulon

(Received in UK 13 March 1970; accepted for publication 9 April 1970)

'Weatanent of an acetic acid mspenelon of lr4,~,6,7,8~ph~l-1,4-ooddo-1,2,3,4~~~bydro-2-naphthaldehyde (la, the Mels-Alder adductof hexaphe~llsobenmfuranliuronlthaorolein) with gaseoue hydrogen chlorideat ambient temperatureyielda moderatelysoluble 2-phe~ql-3,4(tetraphenylbenso)-9-chlorofluorene (5 malting point 193. dec.)2 in about %# yield.

The structureof 2 wan establishedfrom the followingevidence: a) KLemntal analysis (reorystallised from bensene-ethanol).Found: C, 89.40; B, 5.09; Cl, 5.65. Calculatedfor C,,H,IClrC, 89.43; H, 4.M; Cl, 5.62. b) Lability of chlorine (positivereaction with silver nitnate). o) NMR spectrmn3(carbondimlfide solution):singletat 5.83$ suxloaplex multipletat

1889

NO.22

1890

6.h to 7.6 6 in approximatelythe correct ratio (1 to 30). d) U.V. spectrum:h _

(ethanol):2h3, 277, 370 mp

. (Low solubilityin ethanol precluded

an accuratedeterminationof the extinctioncoefficients,but log t *s were estimatedto be between h and 5). The infrared spectrumwas inconclusivedue to the complexityin the 600 - 800 cm-l region, benzene ?) absent in the although2 exhibiteda strong band at 742 cm" (o-disubstituted spectrum of a. Analogous reactionshave been reportedfor the Diels-Alderadducts of acroleinwith 1,3although in neither instancewas diphenylisobensofuran4 and 1,3,4,7-tetraphenylisobenzofurar? the structureof the chlorinatedproduct established. In the latter case, 2-chloro-1,4,5,8tetraphenylnaphthalene was suggested'as a possible structureon the basis of satisfactory elementalanalysisand UV spectrum identicalto that of 1,4,5,84atraphenylnaphthalene; however, both analysis and spectrumare also consistentwith the fluorenederivative. In both of these were also isolated,but we have been cases4'5,the correspondingphenylated2-naphthsldehydes unable, thus far, to prepare the analogous1,4,5,6,7,8-hexaphenyl-2-naphthaldehyde (I).

3

Preparationof the fluorene derivative,1, is an example of an extremelyfacile intramolecularhaloal@lation reaction6. The fact that previousworkers495 were able to isolate the pheqvl-substituted 2-naphthaldehydes as well as the chloroalblated compoundsindicates that aromatizationprecedesring closure. Our failure to isolate the aromatizedaldehyde, 3, could be the result of extra crowding caused by the phenyls at positions6 and 7 pushing the pheql group at position1 into closer proximitywith the aldehydegroup. Attempts to make the hexaphenylisobenaofuran - methyl vinyl ketone adduct (la) undergo

l

rrbilar

(&)

chloroall@ation reactionfoiled, as did attempts to make f&e aorylonit&le adduct

undergo an intramolecularRoesch acylationreaction' (uelnghydrogen chloridewith or

without added sine chloride)to form the fluorenonederivative. In fact, both &and

&failed

899 . even to aromatlseunder these conditions

Actiowledgement. The authors are Indebted to theRe6earcb Committeeof the School

of

Arta

and

Sciences,American Unimrsity of Beirut, for finenclalsupport includinga graduatereeearoh assistantshipto one of ua (F. R.).

F&femme8 and Footnote8

61 (l%O).

1. W. Rled and K.H. Bonnighausen,Ann., m

2. Ccmpound2 appears to deccmposewith evolutionof HCl. This pofmlble themal a<4liahatiaa reaction is under Investigation. 3. The benaylicproton of diphenylmetbylchlorideabsorbs at 6.12&

in dan~rochl~of~.

(N.S. Ethacca, L.F. Johnson,and J.N. Schoolerg,High ResolutionNl4RSpectra Catalog,Vol. 1, Varian Aaeociates,1962, Spectcllr No. 176). 4. A. Etienne,A. Spire, and EL Toraunoff, Bull. Sot. Chia. France, 750 (1952). 5. E.D. Bergmann,Sh. Blumberg,P. Bra&a, and sh. Epstein,Tetrahedrar,20, 195 (1%). 6. Haloalkylationsare usually run In the presenceof Friedel-Craftscatalysts,particularq OrgenicReactiona,& zinc chloride. See, for example,B.C. Fuaon amI C.H. Ilclleever, (19/Q);CLA. Olah and W.S. Tolgyesiin

G.A.

Glah,

aFriedel-Grafta

and Related

63

Raactiono~,

Interscience,New York, 19634, Vol. 2, pp. 659-784. 7. P.E. Spoerri and A.S. I)oBoie* OrganicReactions,5, 387 (1949). a. Bergmann and coworkers (Ref. 5)lren

also

umble

to araatiee the ~~lvlqlketone

acrylonitrileDiels-Alderadducts of 1,3,4,‘7-tetrapheqylieobensofuran, but Mume ere

and and eWO@k-

(Ref. 4) did aroarptiee tbere~l~lksforre-l,3_dip~~e~~~~twltL

gaseous wdrogen chloride;the eromatl4 alwlation.

awl

ketone did not, hmver,

uadargo Uor~-

No.22

1892

9. !l'he failars of s its

inability

to undergo the intr8mOleCUl8r8Cylationre8CtiOnis 8ppa3WIItly not due to

to 8romtil;esince 2,3,~,~-tetr8phenylben~oni.trile10 w8a al.90found to be

unreactiveunder conditionsof the Hoesoh reaction. Simil8r conclusion8m&y be drawn about E

(sea footnote 8).

10. R.P. Doming, R.S. Mlner, Jr., L. Rot&mum, 8nd E.1. Becker, J. Org. Chew, 3,

520 (195%).