Tetrahedron Letters No.52, pp. 4551-4554, 1969. Pergaqon Press. Printed in Great Britain.

sm'rmms AI#D PRoPERTIE OF 3.4'-POL~I~11

Kojl Yamamoto, Take81 Horlkawa and Masao Nakasakl Department of Chemistry, Paoulty of Englneerlng goienoe

Osaka Unlver8lty, Toyonaka, Osaka, Japan

( Received in Japan 2nd September 1969; received in UK for publication 8th October 1969)

Non-ooplanarlty2) of two benzene rings in blphenyl derlvatlves had been realized only in the blphenyls with bulky group8 situated at o,o*-po8ltlon8.

In preceding two papers 3.41, we reported the synthere8 of two general systems (1) and (2). uhlah have polymethylene bridges rpannlng 2,4*- and 4.4*- poeltlons respeatlvely in blphenyl system.

(1) a_, 1-1 (2) a , ~11 d*, 1~14 (3)a. n=9 bw * -8 o * -9 d*. -10

b*. n=12 e , 21~15 o , n=13 r , n-16

-. b; hrio c * n=ll d, n-12

( l These aompounds have been reported in the preoeding papers 3.4). )

In the compound8 (1)3*5) with suitable length of polymethylene bridges, the two benzene rings oann't be ooplsnar and thla reflect8 in the&r anomalous nltra- violet and n,m.r. speotra. Whereas, aompletely different eituationglvesrise in the aompoundlr (2)4*7) ulth p,p'-polymethylene bridges whlah forae the moleoules to take ooplanar conformation.

In this oommuniaatlon, we ulsh to report the syntheses and propertlee or another type of blphenyls whlah have polymethylene bridges spannlng 3.4Lposltlon. Examination of molecular models suggests that 3,4'-bridge appear8 to make the tuo benzene rings perpendlonlar more effeotlvely than the 2,4@-bridge, and the lowest member can be made wlthoat bond deformation ull3 be (3b), nolo.

Preparation of 3.4°-Polymethyleneblpheny18 (3). The oompounds needed for this study were synthesised by the soheme outlined

In Chart I. The general approaah 1~18 analogoue to that developed in prevloas In- vestigations of 2.4'0 and 4.4'.polymethyleneblphenyl8. Starting from gphenyl- cyclohexylacetate (4). the syntheses OS the oompounde (3) with even- and odd- numbered polymethylene bridges follor different routs.

Prledel-Crafts aoylation with sucolnio anhydride gave (5). shlah ua8 oon- verted Into the dleeter (6) by tion to remove the keto group, aWord glycol. 0) conversion to

the series of reaations; a) Wolrr-klshner redub b) cappe~chromlte oatalytlo hydrogenation to

dlbromlde. d) malonate synthesis.

4551

4552 No.52

The hexah@robiphewl (7). provided by Prelog-Stollacyloln c~cllzatlon of the dlester (6) followed by Clemmeneen reduction, -8 heated rith lO$ W/C (320')

to give ~,4Ldeoamsthyleneblphenyl (PI. I.P. 75-76'. After the side ohaine of the dlester (6) were extended by routine method

(Via ayanlde), the resulting dlester (8) nas ayollzed by aeyloln condensation. Clemmensen reduction, followed by dehydrogenatlon yielded dodeeamethyleneblphenyl

(PI* mop* 70-71'. For the series of oompounds with odd-numbered polymethylene bridges, the

side ohaln of the intermediate (4) was first extended to afford ~phenylcyclo- heqlbatjrate (9) uhloh nas then treated ulth f-earbomethoxybutjryl chloride in oarbon tetraehlorlde to afford the keto-oarboxHate(10). By the parallel seqnence of reaotlone with even-numbered polymethylene bridge compo~ds, the oompound (10) *as oonverted into nonamethyleneblphenyl (9). m.p. 67-68' and undeoamethylene- blphenyl (3~). I.P. 87-88..

75b (4)

4.

Ei3 coWH2) $02R

(5) (9)

(6)

1 1

O( CR2 1 $+R

(10)

1 4

ggl (~~rcrr,,Po*Me m (7) (8) (11)

+A& & & &

(3b) (3a) (3a) (3c)

I-P. 75-76' rn.P. 70-71' m.p. 67-68' m.p. 87-88.

80. 52 4553

Ultraviolet Absorption Speotn. Fig.1 and Table I reoord the altravlolet absorption speotra data of these

3.4'.polymethyleneblphenyls dth that of >buty1-4f-hextlbfphenyl as a referenoe oarpound.

Regular shift of absorption maxlma toti shorter wavelength with deoreaslng extlnotlon ooef~lolent going from (3d), n=12 to (3b),n-10, aan be ratlonallted by lnweaslng resonanoe Inhibition.

Anomalous behavior observed in (3a). n-9 suggest the warped benzene rings which oan be seen from the Boleonlar node1 of this oompound.

8) Nuolear kxgnetlc Resonanoe Speotra . Although general pattern of the nar upeotra of 3.4°-polymethyleneblpheny18

(3) appears slmllar to that of 2.4'~polymethyleneblphenyls (1). the most eharaa- terlstlo feature observed In (3) IS the multlplet (4H) centered around 8.4tuhloh oan be assigned to the proton8 on the carbon atoms 2 and 9) 3 (Plg.2)10). Bridging 3,4~-po81t10n, these oarbon atoms must surround the perimeter of one of the benzene rings and suffer strong deahleldlng eifeot.

These altuatlons should be realized more effeotively In 3.3°-polymethylene- biphenyls in which the strain Imposed by the tightly d-m polymethylene bridge would cause the blphenyl nuoleus to beaome ooplaaar, and the polymethylene bridge would also be ooplanar with this Iroleoular plane.

Our effort8 toward the synthesis of this line of oompound have been rewarded by sucoessful preparation of 3,3'-deeamethyleneblphenyl, a,p. 58-59. from 3,3L dlaethylblphenyl, and the details till be the eubjeot of a future aommunloatlon.

4.5

0

J

4.0

3.5

I

I I I

240 260 280 rnfi

Table I IJltravlolet Absorption Ikrta

oompound hraex (=)r) E

(30) 250 14500

(3b) 248 16700

(30) 252 18800

(3a) 252 19500

*bllty1-4'- hexylblphenyl 252 19700

Fig. 1. Ultraviolet absorption spectra Of (3) ln n-hexaner _-_-:-,~9; . . . . . ..-.n-lo.-.--'-.blll -----+n=12: -. 3&utyl-4Lhexylblphenyl.

4554 No.52

I I I I 1

rJ3 4 s 6 7 8 9 10

( 3b) p4$ 8.4

:

t)3 4 5 6 7 8 9 10

1)

2)

3) 4) 51

61

71

el

91

10)

(36)

sr\, &q&y)&

a 1

tl3 4 5 6 7 8 9 I.

Flg.2. Nuolear magnetic resonance Spectra. peak positions reported in t-value 10).

REFERENCES This material was presented in part before the 20th Annual Meeting of the Chemloal Society of Japan, Tokyo, March, 1967. G. H. Beaven, *Sterle Effects in Conjugated Systems," Rutterworths, London, 1958, p.22. M. Nakazaki and S. ISOB, Chem. d, Ind., 224 (1965). M. Nakazakl and K. Yamamoto, m., 486 (1965). Inspection of the Dreldlng's molecular model shows that the compound (1) with heptamethylene bridge Is the lowest member can be oonstruoted without bond deformation. We have succeeded to prepare 6) followlng members of the compounds; (la), n=7. b.p. 107-109*/10'2Torr, (la), n=9, m.p. 60.5' whose preparations and properties will be reported elsewhere. The preLlminsrg account was presented berare the 19th Annual Meeting of the Chemical Society of Japan, Tokyo, March, 1966. Since the preliminarg w%licatIon 4) , the lowest menbeT of (2). n=lI. m.p.87' has been syntheslzed6) together with higher homologs, (2c), n=l'j, m.p.102.. (2e), n=15, m.p.129. and (2f). n=16. m.p.111.. The most hlghlg shlelded protons (10.2 ~1 so far observed In pulymethylene- bridged blphenyls are that of 4,4*-polymethyleneblphenyl (2b). The numbering system adapted here is that proposed tn 0. K. SmLtb, "Hridged Aromatic Compounds,* Academic Press, New York, 1964. The spectra were taken In carbon tetrachlorlde on a Nucleomagnetlc Resonance Spectrometer, JNM-4H-100, Japan Electron-Optics Laboratory Co., Ltd.