THE C-2 AND C-3 POSITIONS OF THE HYDROXYL GROUPS IN GITOGENIN, 9-DEHYDROMANOGENIN, AND RELATED STEROIDAL SAPOGENINS

44 Pages·01.803 MB·English

by  SPITZER, PENN F., JR

The Pennsylvania State College
The Graduate School
Department of Chemistry
The 0-2 and 0-3 Positions of the Hydroxyl
Groups in Gitogenin, 9-Dehydromanogenin,
and Related Steroidal Sapogenins
A Thesis
Penn F. Spitzer, Jr.
Submitted in partial fulfillment
of the requirements
for the degree of
Doctor of Philosophy
September 1950
Approved:
hemistry
Head of thb Department
TABLE OF CONTENTS
Acknowledgements
Introduction . . . ..................................... 1
Historical .............................................. 4
Discussion............................................... 16
Experimental . ...........................................25
Cholestan-2//3-diacid from 4-cholesten-3-one. . 25
Cholestan-2//3-diacid from gitogenin.............27
Chromatographic separation of 9-dehydro-
manogenin from manogenin ........... • • • • 3 1
Agavogenin from 9-dehydromanogenin diacetate. . 33
Agavogenin triacetate ......................... . 3 4
Manogenic acid from agavogenin............ . . . 3 4
Dimethyl ester of manogenic acid..................35
Manogenin diacetate from 9-dehydromanogenin
diacetate. • • ................ . . . . . . . 3 5
G-itogenin from manogenin...........................36
Agavogenin from 9-dehydromanogenin diacetate. . 36
Summary. ............................................... 38
Bibliography . . . . . . . . . . . 39
ACKNOWLEDGEMENT S
Sincere appreciation and gratitude is extended to
Dr. R. B. Y/agner for suggesting the problem and for his
valuable assistance and advice throughout the course of
the work. The techniques which he taught, his interest,
and his enthusiasm have contributed in no small way to
the completion of the work.
Acknowledgement is extended to Dr. Robert F. Forker
for the determination of absorption data and assistance
with the structural determination of the new sapogenin.
Acknowledgement is extended to Dr. N. B. G-uerrant
for his assistance in the determination of the absorption
data of certain of the compounds prepared in this work.
Acknowledgement is extended to Mr. Donald Shriver
for his generosity in supplying the 4-cholesten-3-one
and alumina used in this work.
INTRODUCTION
Though the majority of the known sapogenins have been
discovered within the past decade, some of these steroids
have been known and studied for approximately fifty years.
Earlier work with these materials sought to Identify their
structural configurations, while later studies were made
to determine methods whereby they could be converted to
sex hormones and cortical hormones. The latter work has
evoked considerable interest because of the usefulness of
certain of these materials in the treatment of rheumatoid
arthritis and other ailments.
C* 13 V ^
<2 C-C‘V C - c Nc ~ C
General Sapogenin Formula
I ^2 ^3 ^4
a. Gitogenin OH /?-0H allo-H H
b. Sarsasapogenin
(inverted side chain) H p -OH copro-H H
c. Digitogenin OH P-OH allo-H OH
■d. Tigogenin H p -OH allo-H H
e. Diosgenin H /?-OH (5*6-) H
Though a great deal of work has been performed In the
elucidation of the structure of these sapogenins, some of
the finest work has concerned the configuration of the side
chain at C-17, The position of the second group in ring A,
when that ring is disubstituted, and the point of oxidative
ring opening in monohydroxy sapogenins had not been care­
fully or thoroughly investigated. The location of the
hydroxyl group at the C-3 position had been characterized,
but the second group has been placed, at various times, at
either the C-2 or the C-4 position. Similarly, the open­
ing of ring A in monohydroxy sapogenins has been postulated
to occur at either the 2,3 carbon bond or the 3,4 linkage,
depending on whether the hydrogen atom at position C-5 is
of the copro- or alio-configuration or depending on other
hypotheses which were not substantiated by suitable exper­
iments with the particular sapogenins in question. Such
uncertain concepts of the structural configuration of these
materials have resulted in a badly confused literature.
Since polyhydroxy sapogenins possessing the allo-con-
figuration at the C-5 position have been converted to
gitogenin (la) as a reference compound in attempts to
clarify their structures, it was felt that the definite
determination of the location of the hydroxyl groups in
ring A of gitogenin would serve to identify the location of
the second hydroxyl group in all of the polyhydroxy sapo­
genins which possess two hydroxyl groups in ring A and which
have the allo-configuration at position C-5* Such a study
would also serve to elucidate the structures of the dlcar-
boxylic acids formed on the oxidative cleavage of ring A in
monohydroxy sapogenins which possess the alio-configuration
at the C-5 position.
The establishment of the positions of the hydroxyl
groups in the A ring of dihydroxy sapogenins of allo-con-
figuration supports the evidence for the characterization
of 9-dehydromanogenln (XII, as diol), a new steroid
sapogenin isolated in the course of this work.
HISTORICAL
The nomenclature of the sapogenins, their uses,
general reactions, and discovery will not be presented here,
6 19 30
since excellent reviews are available * * and the
material is too involved to warrant presentation at this
time.
Though the side chain at position C-17 in cholestane
(Ilia) and coprostane (Ila) differ from the side chain
present in a similar position in sapogenins (I), the latter
are often referred to as being of the cholestane or coprost­
ane configuration, depending on whether they possess a
hydrogen atom at the C-5 position which is of the allo-
or copro-configuration. The latter differentiation will
be used in this text.
£7
1-c-c-c -c-c
c
H
Coprostanes
II
a. Coprostane H
b. Coprosterol /3 -OH
c. Coprostanone =0
5.
r-c-C-C-C-^
znr
1
Cholestanes
III
R1 R2
a. Cholestane H H
b. Cholesterol (3 -OH (5,6=)
c. Cholestanol f3 -OH H
d. 2-Cholestene (2,3=) H
e. Cholestanyl chloride Cl H
The oxidative rupture of ring A to form dibasic acids
from coprosterol (lib) and coprostanone (IIc)^* ^ gitogenin
(Ia),^ cholesterol (Illb),-^ and cholestanol (IIIc)^
appeared in the literature during the period 1913 to 1918.
No serious attempt was made to determine the structure of
these compounds, though they were later referred to as
"known" compounds. At that time the structure of the
steroid nucleus was thought to possess a four-carbon chain
39
in place of the now-accepted ring B.
In 1919, Windaus and Dalmer^ proposed that cholesterol
(Illb) possessed a double bond at the 6,7 position in a six-
membered ring B and a hydroxyl group at the C-4 position.
This molecule, on oxidation, was thought to yield a dibasic
acid through the rupture of the 3,4 carbon linkage. These
conclusions were based by analogy to the formation of cyclic
ketones and anhydrides from piraelic and adipic acids by
Blanc.1 In succeeding publications, Wlndaus and co-workers
claimed that ring A ruptured, on oxidation, at the 3,4
carbon linkage to form dibasic acids from cholesterol
(Illb)^2* coprosterol (Ilb),^^ and gitogenin (Ia)."^
During this time, the concept of the structure of ring B
was varied between being of the open chain configuration
and the closed ring form. Since only mild oxidation was
required to open ring A, the two hydroxyl groups in
gitogenin were believed to be adjacent to each other and,
from Windaus' work-^ were believed to occupy the 3,4
positions.
By 1932, Windaus v had revised his previous conclusions
and had assigned the presently accepted six-membered ring
structure to ring B, the location of the hydroxyl group of
cholesterol (Illb) at C-3, and the oxidative rupture of ring
A to occur at the 2,3 positions. He had again used Blanc's
work1 in the elucidation of rings A and B. This work was
also in substantiation of an earlier paper by Windaus,
70
Staden, and Seng. It was at this time that Rosenheim
22
and King were postulating the use of four six-membered
rings in the steroid nucleus. However, they made no
mention of the location of the substituent groups.
In studies with sarsasapogenin (lb) and gitogenin (la),
9 25
Jacobs and Simpson * referred to the 3,4 carbon linkage
as being ruptured on oxidation. This conclusion was reached
because of the similarity of their products to the compounds
"5b 27
prepared by Windaus. In 1935, Tschesche and Hagedorn 1
converted digitogenin (Ic), gitogenin (la), and tigogenin (Id)
to dicarboxylic acids, the latter two acids being identical.
They postulated, on the basis of the earlier work of Windaus,
that the acids were the result of the rupture of the 3,4-
carbon bond, that gitogenin possessed two hydroxyl groups
at these positions, and that tigogenin possessed one hydroxyl
group located at one of these two positions. No attempt was
made to identify the location of this hydroxyl group in the
latter except by reference to Windaus' work.
Jacobs and Simpson^0 performed some interesting experi­
ments with gitogenic acid (IV) which they had obtained from
the oxidation of both tigogenin (Id) and gitogenin (la).
They showed that both hydroxyl groups were located in ring A
by the formation of an acid anhydride from a dibasic acid
which had been obtained from the oxidation of tigogenin;
tigogenin being known to possess one hydroxyl group In ring
A. They found that saponification of one of the ester
linkages of the dimethyl ester of gitogenic acid was easily
accomplished in a short time and under mild conditions,
while the remaining ester group was retained Intact. This
finding was interpreted to mean that the two carboxyl groups
were unequally effected by the remainder of the molecule and
therefore, that they were attached to the molecule by carbon
chains of unequal length. This meant that the acids had