The Structure of Triterpene Alcohol

167 Pages·47.355 MB·English

by  Ames, Thomas Rawlinson

A THESIS
Submitted in p art fu lfilm en t of the requirem ents
fo r the Degree of
DOCTOR OF PHILOSOPHY
a t the
U1JIVEBSITY OF MANCHESTER
by
TIIOMaS RAWLIKSON AMES.
Mayf 1951#
ProQuest Number: 13916626
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THE STRUCTURE OF THE TRITERPKBB ALCOHOL, LUPEOL.
THESIS SUMMARY# (T.R. AMES, Ph.D. 1951).
The preparation of p -lupene (H cilbron, Kennedy
and Spring, J ., 1938* 329), has been re -in v estig a te d .
R epetition of the Clemnonsen reduction of lupenonc gave
no (3 -lupene. Instead, a new hydrocarbon,
lupene-I was iso la te d .
These re su lts suggested th at lupeol d eriv ativ es
were ra th e r sen sitiv e to acid ic conditions, and a fte r a
prolonged se rie s of experim ents i t was found possible to
isom eri3o lupeol d eriv ativ es in to the corresponding
compounds of the S -any re no 1 se rie s. S im ilarly,
& -amyrcnol d eriv ativ es were prepared by th is method
from the (3 -amyrin se rie s.
Thus two of the three m ajor groups of pentacyclic
trite rp e n e s have been in te r-re la te d . I t follow s th a t
compounds of the (3 sm yrin and lupeol se rie s aro
id e n tic a l in rin g s A, B, C, and D, except fo r the
presence of the ethylenic bond in ring C in the P -unyrin
se rie s and a possible stereochem ical d ifferen ce a t C ^ g j,
i .e ., the junction of rin g s D and E.
(I) (II) (III)
I f stru ctu re (I) is accepted fo r (3 -am yrin, then
i t follow s from the re su lts described in th is th e sis,
th a t lupeol must be represented by form ula (II)*
By the use of m ilder acidic conditions than were
used in the above iso n eri sat ions, the conversion of
lupenone in to another mono-un saturated i saner, luponone-I
(corresponding to the parent hydrocarbon lupene-I) has
been achieved* The corresponding alcoh ols, both
saturated and unsaturated, have been prepared and
oxidative degradation reactio n s carried out on them*
The re su lts of these ex p eriren ts show th a t a new type
of trite rp e n o id nucleus is involved, containing a
tris u b s titu te d double bond, and the reactio n s studied
are in terp reted on a b asis of form ula ( I I I ) .
The author wishes to express h is sincere thanks
to P rofessor E*R*H, Jones, F*R«S*, and Dr. T*G* lia lsa ll
fo r th e ir stim ulating advice and guidance throughout
the course of th is work, to M essrs. E*S, Morton and
H. Sw ift fo r m icroanalyses, and to Miss E*K, F u ller
and (the la te ) Dr, H.P* Koch fo r spoctrographic data*
THE STRUCTURE OF THE TRITERPENE
ALCOHOL* LUPEOL*
Section* Page*
I* Occurrence and General P ro p erties
of T riterp enes ******* * * ••••••* • 1
II* The Pentacyclic T riterpenes ••••••* * •••• 5
III* The Chem istry of Lupeol ••* * ••••••* •* ••• 18
IV. D iscussion of Expex*imental Work • • • .......... 47
V* Experim ental * •••••* •* •* •••.............*.............. 86
VI* L ist of R eferences ..........••* •••••••••* ••• 124
Appendix* A. P ro p erties and C onstants of
Compounds prepared in the
course of th is Work * •••••••* •* • (i)
Appendix* B. B otanical Sources of Lupeol *•** (xlv)
(Formulae in Sections I - I I I are numbered consecutively
section IV contains a separate sequence of form ulae).
I , INTRODUCTION.
1# Occurrence and General P ro p erties,
The trite rp e n e s have been iso lated from many
w idely d istrib u te d m aterials of vegetable o rig in , where
they occur in the free sta te or combined as e s te rs or
glycosidos (the triterp en o id saponins)# Thus sla re sin o llc
w
acid occurs as such in Siam Gum Benzoe' , lupeol has been
iso lated as the cinnamate from Gutta Pereha' , and the
saponin from the C alifornian sanroot y ield s echlnocystlc
acid a fte r acid h y d ro ly sis'* # T riterpenes of animal
o rig in include squalene^4* ^ from sh ark -liv er o il, anbreln
from am bergris, and wool fa t y ield s both agnosterol '
and la n o ste ro l^ 0^ ^# The la tte r , which has also been
obtained from y east, is as yet the only trite rp e n e
iso lated from both p lan t and anim al sources# Ho
d e fin ite theory has been advanced to account fo r the
presence of trite rp e n e s in p lan ts or anim als but i t is
possible th a t they, lik e the simple te rp e n e s ^ ^ possess
some p ro tectiv e function against ex tern al damage#
In general they are co lo u rless, non~nitrogenous
m aterials which are b est p u rified and separated by
chrom atographic methods. They ex h ib it the general
phenomena usu ally associated w ith larg e m olecules, and are
generally ch aracterised by m eltin g -p o in t, sp ecific
ro ta tio n , u ltra -v io le t lig h t absorption, and the
preparation of d e riv a tiv e s. In add ition to these d ata,
the mixed m elting point and in fra -red spectra have been
used fo r id e n tific a tio n purposes. D ifferen t d eriv ativ es
of the same substance have been known to give no
depression of m elting-point a fte r mixing^i4 ^. The
colour reactio n generally applied is th a t of Liebom ann
and B u rc h a rd ^ f1^ ^ .
They arc in itia lly distinguished from the ste ro ls
by th e ir fa ilu re to y ield insoluble d ig ito n id e s ^ ^ and
by the fa c t th a t, although the ste ro ls y ield the D iels
hydrocarbon^ ^ on selenium dehydrogenation, the
trite rp e n e s in v ariab ly give a m ixture of c h a ra c te ristic
naphthalene homologues^**2 0 f 23 73) ^ These
1
c h a ra c te ris tic s, together w ith the ap p licatio n of the
method of m olecular ro ta tio n d ifferen ces^24* ^ * ^ 7 )
provide the inform ation which, ap art from the more
d etailed chem ical behaviour, d istin g u ish es a trite rp e n e
from a s te ro l.
2. C la ssific a tio n .
The trite rp e n e s of known stru ctu re f a ll in to two
main groups, the f i r s t of which includes the open-chain
Pl a t e . I
s q u a l e n e . ( i ) A m R E l N / l L )
-?i Ik
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(X -A N Y R IN
X ^ s ^ X ^ C H
leJ.c
<H, - 7 H
, 5 C« ^ T c o
ii
c
cw3 ch5
L A N O S T E R O L ( vT[)
l u p e o l .(y ) . 0 ^ c ^ ) . G E R M A N tC O L .(m ).
B E T U L I N (myft-CHzOH)