furanodiene, a precursor of furan-containing sesquiterpenoids
TRANSCRIPT
Tetrahedron Letters No.8, pp. 931-933, 1968. Pergamon Press. Printed in Great Britain.
FURARODIENR,
A PRRCURSOR OF FURAN-CONTAINIIPP SPSQUITERPBNOIDS
Pharmaceutical
In continuation of
Roscoe jZkgSberaceae>,
H. Hikino, K. Agatsuma, and T. Takemoto
Institute, School of Medicine, Tuhoku University, Sendai, Japan.
(Received in Japan 9 October 1967)
our study on the constituents of the rhizome of sedoary, Curcuma redoaria --
we have recently leolate a novel seequiterpenoid, for which the neme
furanodiene is proposed. We now wish to report that furanodiene possesses the structure I and
fe ea=eqmrrt'LQ- tie _ua6ath‘Le m~jxeerrrraar af aeaqutterpeo&~a wsskrMrrgfu~~,
I
2’ IO0 0
+
I I 12 /
I3
Ii I
Furanodiene, m.p. 44-45', [(I$, f O", has the molecular formula C15H200. In order to eluci-
date the structure, wAysi of the BlfR specbm wi%h tie eid of louble reaonanc8 8rp8ri~tmts wan
*1 partifou2ar2y iztetrrLctfv.3. rate sppcrctrum exhibits three tiny2 methy signals at 2.26, 2.59, and
1.91 p.p.m. as well as three vinyl hydrogen sieals at 4.96, 4.76, and 7.05 p.p.a. lheee hydro-
gens CM be classified into the sebsequent three functions. lhe methyl doublet at 1.91 p.p.m.
and the slightly multiplying quadruplet at 7.9 p.p.m ., spin-coupled eaob other (J-l.3 o.p.s.),
indicate the preaenoe of a furan nucleus bearing a &methyl (Ctl3)"3) snd an a-hydrogen (C (12)H).
Mutual couplinga are also observed between the methyl signals at 1.28 and 1.59 p.p.m. (C (15)"3 and
Ct14)H3) and the hydrogen signals at 4.96 and 4.76 p.p.m. (C(l)H and C (5)
H), respectively, a fact
which demonstratee the presence of two trisubstituted double bonds. Purthermors, both vinyl hy-
drogen signals (C(l)" and Ct5) H) occurring as broad triplets (J-7 and 8 0.p.s.) show the couplings
with the Wraent aethylene gmupinga tC(2f2 a? C(6)H2), respectively. TW additional si-1~
arising from tw methylene groups (Ct9)H2 and C H (6) 2
) rpperr ee a broad quadruplet in an AB type
at 3.44 and 3.52 p.p.m. (J-17 o.p.8.) and as a broad doublet at 3.08 p.p.m. !Jhe signal for the
931
932 No.8
former methylene (C (9)H2) is long-range coupled with the a-hydrogen (C (12)
H) of the furen, the
VWlic methyl (C(ls) II ), and the latter methylene 3 (C (6f2) ’ This finding reveals that the
methylene (C(9)h2 ) is oriented at the a*-position of the furan ring and also attached to the oar-
bon (C-10) bearing the vinyl methyl. The latter methylene signal (C(6)H2) has the appearance of
a broadened doublet, the large eplittlng (J&I c.p.6.) resulting from the ooupling to the vinyl
hydrogen (C(3)") and the small splittings from the couplings to the vinyl nethyl (C(14)H3) and the
allylic methylens (C(9)B2). Ime above IWR evidence leads to the formulation I for furanodiene.
lbe structure (I) of furanodlene thus deduced was confirmed chemically by the following ob-
servation. Pyrolysis of furanodiene resulted in a Cope rearrangement giving ourserene (II), an-
1) other conrtituent of the aedoary rhisome.
8,12-Oxido-germacra-1,4,7,11-tetraene (I), which is presently designated as furanodlene, has
been one of the missing links in the seequiterpenoid biosynthesis, and novmuatbe recognieed as
the common precursor of monocarbocyclia and bicsrbocyclic sesquiterpenoids possessing furan
*2 rings. In reality, the sedoary rhisome, for instance, contains a number of its descendants;
L.e.t 1) curserene (II), ourserenone (III), eplcurserenone (IV), zederone (V), 2, and curcolone (VI)!)
We the& Dr. II. C. Woods, Varian Associates, for the lUDR experiments.
*1 The NHR spectrum was recorded at 100 Ha.p.s. in CCC13 nolution s. m as internal standard.
+2 lhe furopelargone~ are the known exoeptionn, apparently following the different biogenetic
pathww?)
1) H. Hikino, K. Agatouma, and T. !hkemoto, Abotract of the 6th Annual Meetin& of th0 'Ibhoku
No.8 933
wench of the Pharmaceutical Society of J~D~uI, Sendai, 6 (1967).
2) H. Hikino, S. Washi, Y. Sakurai, T. Tekemoto, and N. S. ~CC8, Chem. Pheum. till., 14,
550 (1966). II
3) H. Hikino, Y. Sakurai, and T. Tekemoto, Chem. charm. Bull., 2, 1065 (1967).
4) 0. wtae, J. C. N. MS, J. A. McCloskey, and R. E. Wolff, Tetrahedron, 2:, 1769 (1964).