furanodiene, a precursor of furan-containing sesquiterpenoids

3
Tetrahedron LettersNo.8, pp. 931-933,1968. Pergamon Press. Printedin Great Britain. FURARODIENR, A PRRCURSOR OF FURAN-CONTAINIIPP SPSQUITERPBNOIDS Pharmaceutical In continuation of Roscoe jZkgSberaceae>, H. Hikino, K. Agatsuma, and T. Takemoto Institute, Schoolof Medicine, TuhokuUniversity, Sendai,Japan. (Received in Japan 9 October1967) our study on the constituents of the rhizomeof sedoary, Curcumaredoaria -- 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 formulaC15H200. 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 exhibitsthree tiny2methy signalsat 2.26, 2.59, and 1.91 p.p.m. as well as threevinyl hydrogensieals at 4.96, 4.76, and 7.05 p.p.a. lheeehydro- gens CM be classified into the sebsequent threefunctions. lhe methyl doubletat 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.), indicatethe preaenoeof a furan nucleusbearinga &methyl (Ctl3)"3) snd an a-hydrogen (C (12)H). Mutual couplinga are also observedbetweenthe methyl signalsat 1.28 and 1.59 p.p.m. (C (15)"3and Ct14)H3)and the hydrogensignalsat 4.96 and 4.76 p.p.m. (C(l)Hand C (5) H), respectively, a fact which demonstratee the presenceof two trisubstituted doublebonds. 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 methylenegroups (Ct9)H2and C H (6) 2 ) rpperree 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 doubletat 3.08 p.p.m. !Jhe signalfor the 931

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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).