Dihalocarbene addition to benzocyclopropene

Tetrahedron Letters,Vol.29,No.6,pp Printed in Great Britain

DIHALOCARBENE

ADDITION

Shinzo * Department

Department

Faculty

Applied

Chemistry,

Nagoya

Institute

Gokiso-cho,

Showa-ku,

Nagoya

466,

corresponding

reacts

the

Herein When

equiv.

we

(1)

aq.

report

was

sodium

temperature

for

Benzocyclopropene

was

also

conditions

/ KOBu-t

was

Several initial

mechanisms

displacement

of

by

by

ring

the

the

the

slow.4)

by

(refluxing

the

Thus

path A

reported. catalysed

or

predictable

other

at

b,

all

and

33%

of

Technology,

dichlorocarbene

to

the

u-bond

(path give

anion a,

Scheme); form

under the

the

the

radical the

been thus

TEBA

in

at

30

room

7,7-dichloro2)

respectively. under

give

(6a)

observed

in

homogeneous 63%

reaction:

followed

yield;

(ii)

for

the

(path ring

in

formation to bond

of

(1)

the

the by

a

is

to

be

known of

known

to

very

dihalocarbene to

form

is (6a)

liberate

of

a tribromomethyl

rupture

by

carbenes

conditions

radicals

amount

dihydrophenanthlene, Furthermore,

a radical

675

of

followed

anion.

5)

apply.

ionic

of 1)

41,

followed 3)

participation

is

the

Scheme).

involving

of

or

phenyl(tribromomethyl)mercury

organomercurial

products.

cleavage (3

addition

c,

by

intramolecular

homolytic

intermediate

(i)

moiety

by

bicyclobutane(s),

typically

presence

of

and

cheletropic

cyclopropene

C-C-

no detectable

chloroform

cyclopropene

(21,

process

unlikely

process

the

Scheme);

(iii)

with

of

and

to

the

a diradical

intermediate is

publisheo

yield.

oenzyl

the

has

been

dihalocarbenes.

yields,

6h),

for

min);

olefins

dibromocarbene

OC,

of

(1)

never

amount

91%

with

20

evidence

of

and

the

the

with

(6a)

posturated

to

examples

by

96

(1)

with

a catalytic

cycloreversion

Scheme

However,

afforded

influenced

30

reaction,

reaction

(1)

of

ion

definitive

specific

6)

of

has

bromoform

be

to

reaction

the

with

to

the

n-bond

without

a of

few

form

(path

benzene,

dibromocarbene

of

pentane,

in

fission

Moreover,

afforded

of

equiv.

react

may

+ o2a]

Nucleophilic

carbenes

reaction

found in

halide

the

[a2s

with

in

dihalocarbene

to

synchronous

to

closure

dihalocarbene

University,

Japan

dibromo-

benzocyclopropene

obtained

fission

anion

u-bond

10 and

recovered

nucleophilic

trihalomethyl

with

7,7-dibromobenzocyclobutene were

(1)

the

to

(6b)

unchanged

of

hydroxide,

(CHBr3

Gifu

Japan

smoothly

behavior

upon

exposed

3h,

benzocyclobutene

501-11,

Education,

7,7-dihalobenzocyclobutene.

cycloaddition 1) the increasingly,

far.

of

**

Saito

of

give

studied

Katsuhiro

Chemistry,

Benzocyclopropene

While

BENZOCYCLOPROPENE

of

Summary: the

TO

and

Kagabu*

Gifu **

0040-4039/88 $3.00 + .oO Pergamon Journals Ltd.

675-676,1988

trap

should

the such

have

of

a phase

be

minor.

been transfer

In

fact,

dihydroanthracene reaction

as

cumene.

was

not

These

the

676 CH; Scheme

;“‘;.; a 2'

11

+

CX2'

6a:

X=Br 6b: X=Cl

5 results do

not

could

lead

immediately

intermediate

attempt

in

to

such

clarify

References 1)

a.

to

wish

and

Halton,

cited

and

2)

The

the

rapid

b,

Scheme),

mechanism

they

involving

intramolecular

radical

Further

system.

however,

studies

coupling are

underway

in

mechanism.

thank

Professor

Eng. H.

J.

spectra

H.

Chem.

Kato

Halton

Professor

8.

Prinzbach

for

Prod.

and

S.

M. Muchowski, S.

of G.

O'Leary,

reaction

(path

his

for

his

helpful

continuing

advice.

encouragement.

Footnotes:

and

W. M.

Abau-Teim,

for

that

fused-ring

authors

thank

E.

Ishihara,

unique

the

threin;

Martin

an

formation

a preference

to

poss ible

is

The

Acknowledgement:

We also

it

(5);

occur

diradical

incipient

contradict

Kagabu,

2. 6a

Richardson, C.

Goodland,

=.,

6b

z.

were

349

-Chem.

Chem.,

Chem.

and

Is,

J.C.S., ---

Org.

Bull.

compounds

e.

Toda,

49,

1040

Jpn.,

60,

identical

and

D.

Wege,

Tetrahedron,

and

J.

F.

McOmie,

510

(1984); 4141

to

and

W.

(1980)

Commun.,

K.

SaitO,

J.

C.

H.

(1987).

those 11,

J.C.S.,

references

(1982);

published: 813

(1981);

Perkin

Trans.

M. A. 0. I,

2659

(1983). 3)

R.

4)

A.

8.

77,

Woodward

Verlag R.

Chemie

Browne

nucleophilic

recovered

and

and

5)

D.

Seyferth,

W.

von

E. U.

Halton,

g. Doering

with

Chem. and

excess

Misslitz,

X.-t. Jr.,

(Received

in

17

F.

2,

20

65

der

Orbitalsymmetrie

I’,

S.

Ding,

November

A.

Jr.,

and de

345

lithium

OC after

(1977). has

thus

attempted

Our far

failed;

1 was

20h.

(1972).

Coburn,

and

2,

methyl

at

s., J.

M. Jones, Japan

Erhaltung

Tetrahedron,

quantitatively

Misslitz,

Shiue,

I* Die

Hoffmann,

(1970). B.

reaction

almost

6)

B.

M.

Tetrahedron Jones,

Meijere,

1987)

Jr., ibid.,

w., ibid., 5403

991 5399 (1985).

(1965); (1985);

G.-H. U.