Decamethylanthracene and its 9,10-‘DEWAR’ isomer

Tetrahedron Letters No. 36, pp 3143 - 3146, 1977.

DECAMETHYLANTHRACENE

Pergemon Press. Printed in Great Britain.

AND ITS 9,10-'DEWAR'

ISOMER

Harold Hart* and Bernd Ruge Department

of Chemistry,

Michigan

State University,

East Lansing,

Michigan,

48824

(Received in USA 20 June 1977; received in UK for publication 14 July 1977) Peri interactions sult in unusual

in naphthalenes

and anthracenes

Anthracenes

reactions.'

with a double-peri

Cl, 8 and 9) or with two peri interactions 10) may be unstable

(Le.,

distortions

interaction

substituents

(a,

which may re-

substituents

at Cl, 9 and either

at

C4, 10 or C5,

to the tautomeric form in which the central ring is not aromatic.2 394 1,4,5,8,9_pentamethylanthracene, which has a double-peri methyl interaction,

For example, rearranges

cause molecular

in acid

the synthesis

relative

294 or in base5 to the 9-methylidene-9,10-dihydro

of the fully aromatic

form of these compounds

tautomer.

it is important

Consequently

to avoid

in

if possible

acid or

acidic or base reaction We wish to describe general

to other highly

properties

The synthetic methylnaphthalene

at or after the point that the peri strain

here the first synthesis

and can be extended

has some unusual

formed

conditions

as a consequence

sequence

of decamethylanthracene

substituted,

Our route is

(a).7

aromatics.

6

Decamethylanthracene

of its strain. The key intermediate

is shown in the Scheme.

1, used as an aryne precursor

in only very low (%5%) yield8

strained

is introduced.

in the penultimate

from the readily available'

step.

is the dibromohexaUnfortunately

1 was

1,2,3,4,5,8-hexamethylnaphthalene

and had to be approached obliquely. Addition of bromine (1.3 eq) to a boiling suspension of 4,710 dimethylisatin gave a clear solution from which the monobromo derivative 2 quickly deposited as red crystals, conditions, anhydrous

mp 299-302°C

(ethanol)."

but could be accomplished

A1Br3

(0.16 eq) in fuming

aromatic

protons were absent

alkaline

hydrogen

peroxide

zation gave 2, mp 129-130°C dienone13

sulfuric

bromination

by NMR).12

(explodes).

yield

Dibromide

exceptionally

2 with bromine

2, mp 313-315°~l!ethanol)11

anthranilic

Equivalent

containing

of 2 required

by stirring

acid (20% S03) at room temperature

to the corresponding

in 1,2-dichloroethane

tion ceased,

Further

in excellent

amounts

propylene

to give aryne adduct 2, mp llO-112°C

3143

acid,

severe

(2 eq) and

for 24 h (until was converted

by

mp 175"C, which on diazoti-

of 2 and hexamethyl-2,4-cyclohexa-

oxide was heated

(ethanol)."

at 70-80°C

until N2 evolu14 reduced

Ketone ,$,was rapidly

NO. 36

3144

0

’

boilino ethanol

H

,$ (85%)

5

2 (98%)

@,(88%)

I (75%)

n- u B

by LiAlH4

in ether at 0°C to a mixture

(under argon)

of epimeric

In the final steps to j,, n-;;tyllithium and N-n-butyl-tetramethylpyrrole (ethanol, aqueous

-20"C).11S16

sodium

crystals,.mp

29.29,

427 nm (log ~3.80),

128.46,

in its proton NMR spectrum

The l3 C NMR spectrum

134.52,

136.86).

at room temperature

inherent

(hexane)

in the same solvent

roughly Imirrored the absorption

seven peaks

had Amax at spectrum,

spectrum,

but

at 480 nm. in 1 was evident

on ice to give the colorless

from two experiments.

tautomer

,9, mp 246-248°C

(methylene

A methylene acid

chloride

(violet color),

chloride/ethanol)";

(d, 3H, J = 7Hz), 2.18 (s, 12H), 2.28 and 2.43 (s, 6H each),

(s, 2H).

of l

(C606) at 61.62, 2.02

showed the expected

The uv spectrum

1 (60 mg in 10 ml) was treated with one drop of trifluoroacetic

61.20

amounts

(1 h) to give adduct ,8, mp 108-109°C

405 (3.83), 390 (sh, 3.74) and 283 (5.05), and the fluorescence

with one broad maximum The strain

(in hexane) was added to equivalent

chloride/methanol)."

showed three singlets

127.79,

in mesitylene

acid at 0" in chloroform and 10% 17 by brief reflux and workup gave 1 as yellow, fluorescent

and 2.17, the last due to C9, 10 methyls. (617.27, 23.52,

when refluxed

with m-chloroperbenzoic

followed

(methylene

which,

(ethanol)."

at room temperature

Oxidation

bicarbonate,

210-212'C

Decamethylanthracene

measured

alcohols

for 44 h gave the desired l, mp 177-178X

4.37

solution

of

then quenched NMR (CC14)

(q, lH, J = 7Hz) and 5.24

3145

No. 36

Irradiation converted

of a thoroughly

degassed

isomer fi. 'la

it to the 9,10-'Dewar'

with the symmetry

solution

of this structure

['H(C606):

of 1 (benzene or ether)

through

Pyrex rapidly

The proton and '3C NMR spectra were consistent 61.78

(s, 6H), 1.95 (s, 12H), 2.15 (s, 12H);

H+ (trace)

&!

9 13C: 13.77, 15.28, 15.77, white solid by vacuum rearranges

to 1 (approx.

These studies

128.75,

133.14,

15% in benzene,

We are indebted

to the National

For a review, S.C. Dickerman

3.

M.L. Caspar,

4.

H. Hart, J. B-C. Jiang and R.K. Gupta, Tetrahedron

see V. Balasubramaniyan, and J.R.

Science

Foundation

(GP 43659X)

for finan-

Chem. Rev.,

Bee, 567 (1966).

Haase, J. Am. Chem. Sot., ,&, 5458 (1967); B.F. Bowden and D.W.

J.B. Stothers

5.

H. Hart and H. Wachi, This limitation

involves

and N.K. Wilson,

Can. J. Chem.,

J. Chem. Sot. Chem. Comn.,

clearly

lack an a-hydrogen;

Decafluoroanthracene has been isolated;

appears

in which the C9 or Cl0 substituents of 1,8,9_triphenylanthracenes,

See H.O. House, D. Koepsell

dehydration.

see D. Harrison,

for

and W. Jaeger,

cited therein.

to be the only other simple fully substituted

Decalithioanthracene

1893 (1963).

in press.

the final step in the synthesis an acid-catalyzed

,5J, 1958 (1975).

Lett., 4639 (1975).

does not apply to compounds

J. Org. Chem,, $$, 1167 (1973) and references

3&

as a

it thermally

J. Chem. Sot. Chem. Cotmn., 78 (1977).

6.

7.

can be obtained However

of this research.

1.

example,

a

from these irradiations. 19,20 40", 30 min).

2.

Cameron,

Compound

147.10].'8

of the solvent

are continuing.

Acknowledgement. .cial support

59.23,

removal

M. Stacey,

R. Stephens

has been claimed;

anthracene

and J.C. Tatlow,

see A.F. Halasa,

which

Tetrahedron,

J. Organomet.

369 (1971).

8.

J. B-C. Jiang,

9.

H. Hart and A. Oku, J. Org. Chem., $1, 4269

10.

Columbia

11.

a)

Organic

Spectral

analysis

Ph.D. thesis, Michigan

Chemicals,

State University,

Charleston,

1975.

(1972).

South Carolina.

data were in full accord with the assigned

structure;

b) a correct

elemental

was obtained.

12.

Cf. M. Hellmann

13.

H. Hart, R.M. Lange and P.M. Collins,

and A.J. Bilbo, J. Am. Chem. -- Sot., a,

14.

The reduction,

followed

a.Syntheses,

by IR, was complete

4590 (1953). Coll. Vol. 2, 589 (1973).

in a few minutes.

Overreduction,

$3,

Chem.,

with loss

No. 36

3146

of bromine,

can occur and must be avoided.

15.

E. Wolthuis,

W. Cady, R. Roon

16.

The N-benzyl

adduct was also prepared,

17.

The procedure

18.

The simplicity

Tetrahedron

Lett.,

of the NMR spectra

This possibility We are indebted

was eliminated

Searle,

R.W. Allen,

by a molecular

weight

R.W. Franck,

1,8-di-&-butylnaphthalenes

W.L. Mandella

methylnaphthalane

determination

(H. Hart and A. Oku, unpublished

of a 9,10-photodimer.

(cryoscopic,

by D.E. Applequist

1,4-'Dewar'-anthracene

benzene).

is known; N.C. Yang,

are converted

to 'Dewar' isomers ,!&I,327 (1975).

to a 'Dewar' isomer on room temperature

results).

and R.

,!@, 2297 (1974).

and K.J. Falci, J. Org. ChEl,

is not converted

M.E. Christy

for this measurement.

J. Am. Chem. Sot., Qj, 1389 (1964).

Highly strained

(1966).

P.S. Anderson,

with the symmetry

we are aware of was prepared

R.V. Carr, E. Li, J.K. McVey and S.A. Rice, ibid., 20.

31 ’ 2009 'v\r

in the final step.

3673 (1976).

is also consistent

to Dr. Rodney Willer

The only 9,10-'Dewar'-anthracene

J. Org. Chem _'

but gave poorer yields

was based on that of G.W. Gribble,

and C.D. Colton,

19.

and B. Weidenaar,

on irradiation; However,

octa-

irradiation