The revised structure of isoincensole-oxide

Tetrahedron Letters No

pp 3783 -3786, 1973

39,

THE

REVISED

STRUCTURE

M.L.Forcellese Institute

(Received The from to

zsolatlon

FrankIncense

I, on the 1)

converted 11) epoxlde

ring

the

between

at the during

was, the

free

take

place

place

when

the

usual

are

allowed We

(II-acetate) of

lsomerlc

(I-acetate), from

an

examined

reacts

mth

showed sample

none

of

TLC of

room wluch

on

C

A was

ring

are

when

3a

temp.

I. 3783

(II)

20H34’3 asslgned

of

not

the

1s

(NPA). the

show

Its

intramolecular

between

Intramolecular

(formlng

the

acid

&d of

resin,

rea-

epoxlde

and

wasruledout.

reactlon,

a tetrahydrofuran

Such

treated

abnormal

with

peracldsJ,

corresponhng

ring),

reactlons

0-acetyl

take

whereas derlvatlvl

. as follows. (solvent

appeared

comparlng

of the

presence

proton

another

posslblllty,

at

of

epoxldatlon.

reagents

this NPA

by

that

the

posslblllty

ring)

epoxlde the

for

epoxltic the

reactlon

us2

component

obtalned

supposed

occurs

same

1973) &terpene

vvlth p-nItroperbenzolc

was

hydroxyoleflns

with

monooxldes

to

of

Rome

Structure

dzterpenlc

oxygenated

the

a macrocycllc

reported'.

posltlon,

and

now

authentic

the

course

reactlon

react

as

and

of

conslderatlons

evidence

suggested

appropriate

to

previously

epoxrdatlon

hydroxyl

- Unlverslty

(I),

abundant

a larger

In the

epoxldatlon

have

I,

C.Santarell1

Chemistry

I by epoxldatlon

the

however,

could

most

expected

(glvlng

ISOINCENSOLE-OXIDE

1973,acceptedforpubhcatlon15 August

follolrnng

chemical

compound

bond

the

no

been

the

Into

In

occurrIng

It

yield

sIgna

double

has

(II),

low

Organic

Isolncensole-oxide

of the

Although

resonance ctlon

basis

In

of

resin,

Incensole

OF

Printed in Great Bntaln

R.Nlcolettl

m UK 10 August

of

Pergamon Press

the

to

The

011~

lncensole

aceta

CHCl

), glvlng mainly a mlxtl 3 be Isolncensole-oxide acetate

nuxture

with

I-acetate,

prepared

3784

No 39

The the

less

rlson

mixture polar

mth

an

A more

was

compound

The

abundant

mass

one

spectrometry)

formula

C

The

chromatography

as Incensole-oxide

a new

ldentlcal

an 0x1,

elemental NMR

column

on

acetate

slllca-gel:

(IV),

by

cornpa

.

after

show

1s

and

22H3604*

4

sample

(which

by

ldentlfled

fraction,

polar

compounds

fractionated

was

authentic

lsomerlc more

then

which

column mass

decomposes

analysis

spectrum,

chromatography, spectra)

are

flttlng

in

on

afforded

approximate

tistlllatlon,

U-I agreement

structure

mol.

vvlth the

III,

shows

two

ratlo

95.5.

wt.

(from

molecular

the

following

signals

(3H,d,J = 7Hz)

0.90

and

1.30 (3H,s) (CH3-C-O),

(3H,d,J = 7Hz)

0.98

(I-propyl),

1.12

(3H,s) (CH3-C-O),

1.61 (3H) (cH3-C=), 2.00 (3H) (CH3COO), 2.96 (lH,broad

(-c;?c), 4.91 (lH,broad

(-cH-OCOCH~),

d)

5.29 (1H, broad

slgnal)

showed

two

(HC=C)

(5

d)

,I*

CDC13). A comparison are

they

&fferent.

spectrum

of

of

III

show

I-acetate

Hnth

I-acetate

slmllar,

exhlblts

but

the

1.02 (SH,d,J = 7Hz) (I-propyl);

Careful cannot or

5.91 (lH, broad

(CH-~C~CH~); alkaline

be purlfled

by treatment

mth

hydrolysis

unth

the

usual

p-nltrobenzolc

ldentlcal

following

1.08

(3H) (cH3-c=), 2.04 (3H) (CH3-COO), sIgnal)

not

of

that

the mass

signal) III

affords

techniques.

acid

(CH=C)

by

at room

spectra,

(CH-O),

(6,

CDC13).

in

an unstable

temp.

the

NMR

= 7Hz) and

1.10 (3H,s) (CH3-C-O),

slgnal)

column

derlvatlves and

0.89 (SH,d,J

signals.

(3H,s) (cH3-C-O), 4.24 (lH, broad

acetyl

solId

4.86 (lH, broad

compound,

chromatography (solvent

1.62

CHCl

on

3

) ths

whch

szllca, solld

No. 39

1s

3785

slowly

(m.p.,

converted

NMR

Into

spectrum)

On the

basis

censole-oxide

(I)

to

another

(TLC),

which

proved

to

the

experiments

described

corresponhng

above

we must

now

acetate)

the

followxng

R = H

Since

the

It

hydroxyl rate

between

has

been

enhances

of the

simple

lncensole

and

shown the

that,

rate

of

epoxldatxon NPA,

lea&ng

In

certain

formatlon reactlon to

I,

3a

, we

could

cyclic

favour

for

(I-acetate)

the ether

the

presence

In

Idea

formatlon

Intramolecular

of

reactlon

I, of

by hydrolyses the

free

of

alcohol,

III

that

the

be

tiagrammatlcally

and

subsequent

acid-catalysed

represented

as follows

can

be

of

comparzxson

a to

reactlon

represented

follows

The

xsoln

(I)

hydroxyoleflns, of the

propose

structure

R = COCHg

free

be ldentlcal

I.

of the (and

compound

as

No 39

3786

The -oxide

presence

(I)

accounts

of two for

tetrahydrofuran

all

Its

rings

chemxcal

and

In the

molecule

spectroscopic

of

Isolncensole-

propertles

previously

reported'.

Acknowledgments

- We

are

xndebted

to the

Italian

C.N.R.

for

flnanclal

suppori

References 1

2

M.L.

We

Forcellese,

are

grateful

R.

Nlcolettl

and

to Professor

G.

U. Petrossl,

Tetrahedron

Bert.1 (Unlverslty

of

28,

Plsa,

325

Italy)

(1972).

for

this

suggestlon.

3

a) and

H.B. M.

-Canet,

4

R.

Henbest

and

B. Nxcholls,

Mousseron-&net, C. Levellols

Nlcolettl

and

M.L.

Bull. and

H.

J.

Chem.Soc.

Soc.Chxm.

Huerre,

Forcellese,

IbId.

Fr.

221

1751

658

Tetrahedron

(1959), (1969),

b)

c)

(1966).

3,

6519

(1968).

J.C. M.

Lanet

Mousseron-