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Diastereomeric Secalonic Acids.

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equilibrium mixture of ( I ) , (2) and (3); compound (5) was
rearranged, with a 1,s-homodienyl hydrogen shift [3], into
bicyclo[3,3,0]octa-2,7-diene.The photolysis of (3) gave rise
to ( 4 ) , (5), and (7)-(10).
ponent A. The mass spectra of secalonic acids A and B show
the same molecular peaks (at M = 638) and the same fragmentation. Both acids have identical chemical formulae,
ultraviolet spectra, functional groups, and exhibit the same
reactions on degradation with alkali, but have different
melting points RF- values, and optical rotations (cf. Table 1).
They are therefore diastereomers.
Table 1. Properties oE the diastereomeric secalonic acids A and 9,
C32H30011 (mol. wt. 638.6).
M.P. [ “ C ](from CHCI,)
[a]: (pyridine)
246-247 (decomp.)
The formation of ( 4 ) and (5) in 22 and 10 yields indicates
that they originate from (2) which occurs as an intermediary
product. This assumption could be supported by photolysis
of 5,8-dideuterocycloocta-1,3,6-triene(3a). Its product of
isomerisation (4u) showed a distribution of deuterium which
2), by way of
corresponds t o an isomerization (3) + (
a 1,5-hydrogen shift [4].
Compound (7) was forme&, on the other hand, without
hydrogen shift: The product (7.)
which was obtained on
photolysis of (-?a), carries deuterium only at C-4 and C-8.
I t is suggested that its formation is due t o a rearrangement of
the santonine type [5]. The 1,2-homotropilidene (11), which
would also be expected, is converted t o (8) under the conditions of experiment.
254-256 (decomp.)
[Z 709/545 IE]
Received, March 19th, 1964
German version: Angew. Chem 76, 438 (1964)
[*I Present address: lnstitut fur Organische Chemie der Universitdt Kiel (Germany).
[ I ] Communication No.VI on Ergot Pigments.- Communication
No. V: B. Franek and G . Baumann, Chem. Ber. 96, 3209 (1963).
[2] F. Krafr, Arch. Pharmaz. 244, 336 (1906).
[3] A. Sroll, J . Renr, and A. Erark, Helv. chim. Acta35,2022 (1952).
141 B. Franck, Planta med. 8, 420 (1960).
[51 B. Franck, 0. W . Thiele, and T.Resrhke, Chem. Ber. 95, 1328
(1 962).
[6] J. W. Apsimon, A . J. Corran, N . G . Creasey, W . Marlow, W .
B. Whalley, and K . Y . Sim, Proc. chem. SOC.(London) 1963, 313.
[7] Thin-layer and column .chromatography with a 9: 1 mixture
of chloroform and methyl propyl ketone on Kieselgel G [E. Merck,
Darmstadt (Germany)] impregnated with 6.3 “4, of oxalic acid.
181 C h r y s e r g o n i c a c i d , which was isolated by A. Stoll et al.
[3] and whose structure was recently investigated 161, was found
as already suggested by its low rotation ([a]:= -3 in pyridine)
[3] - to be a 2: 1 mixture of secalonic acids A and B.
Open-chain 1,3,6-trienes can be isomerized in the same way.
is readily rearranged on
Thus 5,5-dimethylhepta-l,3,6-triene
irradiation into a mixture of cis- and trans-3,3-dimethyl-l,2divinylcyclopropane [6].
The structure of (10) was deduced from infrared and N M R
spectra. The formation of (10) is the first example of a
photochemically induced Diels-Alder reaction.
[Z 693/534 IE]
Received, March 12th, 1964
German version: Angew. Chem. 76, 378 (1964)
[I] A . C. Cope et al., J . Amer. chem. SOC.74, 4867 (1952); W. R .
Roth, Liebigs Ann. Chem. 671, 25 (1964).
[2] 0. L. Chapman: Advances in Photochemistry. Interscience,
New York 1963. Bd. I, p. 390.
[3] D.L. Glass, J . Zirner, and S . Weinstein, Proc. chem. SOC.(London) 1963,.276; W. R . Roth, Liebigs Ann. Chem. 671, 10 (1964).
[4] K . J . Crowley, Proc. chem. SOC.(London) 1964, 17.
[51 D . Arigoni et al., Helv. chim. Acta 40, 1732 (1957); D . H . R.
Barron, ibid. 42, 2604 (1959).
[6] Experiments in collaboration with P . Fuss.
Diastereomeric Secalonic Acids [l]
By Prof. Dr. B. Franck [*I and Dipl.-Chem. E. M. Gottschalk
The Structure of Secalonic Acids A and B [l]
By Prof. Dr. B. Franck, Dip1.-Chem. E. M. Gottschalk,
cand. chem. U. Ohnsorge, and Dipl.-Chem. G . Baumann
Organisch-Chemisches Institut der Universitat Gottingen and
Institut fur Organische Chemie der Universitat Kiel (Germany)
The diastereomeric secalonic acids A and B [I] were shown
by degradation [1,2], spectra [l-31, and synthesis of ( I )
[3] t o be symmetrical derivatives of a new type of natural
product skeleton, viz. 5,5’-dihydroxy-8,8’-bichromonyl( I ) .
Moreover, they contain four hydroxy groups, two C-methyl,
and two methoxycarbonyl groups [2]. WhuUey et al. [4] recently suggested an arrangement of the substituents according
t o Formula (2). We were able t o obtain an independent confirmation of the structure of ring C in our pure, diastereomeric secalonic acids A and B by means of mass spectrometry,
ring C being split off as methyl cresotinate, and by degradation with ozone to a-hydroxy-P-methylglutaricacid and
methylsuccinic acid. In contrast t o (21, however, the pdicarbonyl system in the secalonic acids is enolized t o the
vinylogous carboxylic acid (3) [5].
Organisch-Chemisches Institut
der Universitat Gottingen (Germany)
S e c a l o n i c a c i d , the pale yellow main pigment of ergot
(Claviceps purpurea), was originally isolated by Kraft [2]
and has since been investigated by several groups of workers
[l, 3-61. We found that the crystalline secalonic acid obtained
from a number of ergot varieties consists of a mixture of
t w o d i a s t e r e o m e r s . Thus, secalonic acid derived from
German and Austrian cultured ergot and from Spanish wild
ergot could be separated chromatographically into secalonic
acid A (RF = 0.42) and secalonic acid B (RF = 0.64) [7,8].
On the other hand, secalonic acid from a strongly pigmented
Canadian wild ergot contained only the slow-moving comAngew. Chem. internat. Edit. / Vol. 3 (1964)
/ No.6
OH 0
0 I
(The rings are labelled as A, B, and C from left t o right.)
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acid, secalonic, diastereomeric
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