Two new sesterterpene lactones from a sponge

Tetrahedron Letters No. 30, pp 2635 - 2636,

1976.

TWO NEW SESTERTERPENE by R. Kazlauskas,

Ptrgamon Press.

LACTONES

P.T. Murphy,

Printed in Great Britain.

FROM A SPONGE

R.J. Quinn

and

R.J. Wells*

Roche Research Institute of Marine Pharmacology, P.O. Box 255, Dee Why, N.S.W., Australia. 2099

(Becsivcd in UK 14 May 1976; accepted for publication 14 June 1976) Sesterterpenes,

usually

tetronic

acids,

rare in nature,

l-5

sponge family Dictyoceratida

The genus

of which

the simplest

have been

Ircinia

is variabilin

reported

has yielded (11 derived

from many members a series

of the

of sesterterpene

from I.variabiIisl.

This

acid has been found in present work together with the furan (2), previously 7 described from -I.spinosula , and geranyl farnesol (3) 6. in approximately equal amounts tetronic

(0.7% each dry weight) from an Australian 6 from an insect wax containing

Fasciospongia

occurrence Ircinia

of this compound

sesterterpene

biosynthetic

report

tetronic

modifications

the separation

described

suggested

examples

near

(6) in equal

was present

ircinin-1

in which

of

on the

formulae

ions were

the majority

of protons

6.30, 5.95

(lH, d of triplets, 3.70

(1H each, J=lGHz,

(ZH, s; C5-H);

We now

Thorecta

present

in previously

sponge with

dichloromethane

ircinolide

followed

by

(5) and 24-hydroxyircinolide

oils.

of the C5-C6

, (6) C25H2805 were established

bs; 8-furan,

7.26,

C2-H, 5.36

cleavages

reported

informative 6.91

6.08

C7-H);

for

and showed

m.s.

2.40-2.0

C12-H);

the at m/e

the resonancdf

(lH, d, J=lGHz;

Cl-H,

C&-H);

4.87

(6H,m; CIO-H,

and

The peaks 3 (4) .

(1H each, bs; a-furan,

(lH, bt, J=?Hz;

(lH,m; C18-H);

by

(m/e 255, 161 and 811.

and Clo-Cl1

:- 67.33,

7Hz; C16-H); 2.84

sponge

acid moiety

j.

l-4

y-lactone.

metabolites,

(5) C25H2804

as follows

isolated

is an example

from the Australian

the same for each compound

reminiscent

(1) have been

(4), from _-I I.oros

1 The H n.m.r. spectrum of (5) was extremely

C o,-H);

intermediate

structure

the tetronic

freeze-dried

gave two major

(0.6%) as colourless

The molecular fragment

sesterterpene

as an unsaturated

of the powdered

yields

81 and 161 were

of which

Sydney,

gel chromatography

C9-H);

(3) has been type and the

that it was the precursor

(2) was an immediate

o$ two new sesterterpenes

collected

Extraction

major

and that

of the basic

difurano-metabolites

marginalis

silica

acids

strongly

F.fovea).

of the Ophiobalane

pathway.

Several including

in a sponge

(probably

sesterterpenes

described

C4-H, 5.47

(IH, d, J=9Bz;

C1l-H,

Cl7 -H); 1.93

a-

1.65

(3H, s; C24-H); collapsed

the doublets

collapsed

the doublet

the 'H n.m.r. carbonyl

spectrum

grouping

orientation

shown.

(3H,bs; C14 -H); at 64.87 at 66.08

and a doublet

of (5) occurred

(C22-H).

1.07

(3H,d,J=7Hz;

and 1.07 respectively appeared

at 62.12.

as a singlet 67.25

No fine coupling

Irradiation

C19-H).

to singlets,

was observed

at 62.84

irradiation

The remaining

in accord with with CZO-H

at 65.47 resonance

a proton 6 to a

suggestive

of the

in

2636

No. 30

The structure U.V.

spectra

(Amax

(5) was further (M~oH),

supported

283 nm; doubly

at m/e 255 and 137 in the m.s.spectrum of a C17-Cl8 The compared

structure

conjugatedylactone)

which

of (6) followed

1773 cm

-1

: y lactone)

and the cleavages

could be rationalised

of (5).

from differences

The IH n.m.r.

that the the three proton

two proton

singlet

at m/e 153

(C8H903)

at 64.41

of an unidentified

which

and

observed

as both alternative

1 H n.m.r.

was identical appeared

the m/e 137

ions

and m.s.

in general

at 61.93

spectra

features

in (5) was replaced

by the appearance

(C8H9021

when

with

the by a

of a peak

peak in (5).

configuration

The same compounds

Australian

in the

This result was paralleled

replaced

of absolute

of this sponge.

spectrum

singlet

in (6).

in (6), which

The determination collection

(vmax

scissian.

to those

exception

by the i.r.

at C awaits more material from a second 18 have also been detected from a small collection

sponge.

(5)

R

=

CH

(6)

3

R = CH20H

REFERENCES

1.

D.J. Faulkner,

2.

F, Cafieri,

3.

G. Cimino,

4.

R. Kazlauskas,

5.

W.E.

6.

Tjrso

7.

G, Cimino,

Tetrahedron

Letters,3821

E. Fattorusso, S. de Stefano,

OberhLnsli

L. Minale

P.T. Murphy,

S. de Stefano

and L. Minale,

and E. Fattorusso,

R.J. Quinn

and W. Hofheinz;

Rios and S. P&rez

(1973).

C. Santacroce

unpublished

and L. Minale,

Tetrahedron,

and R.J. Wells,

C., -Chem.Commun.,

Tetrahedron,

unpublished

Professor

P. Bergquist

(1969).

Tetrahedron,

for sponge

g,

3,

1315

identification.

1579

(1972).

(1972).

333 (1972).

papers.

results.

214

Acknowledgements We thank

3,