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Constitution of laserpitine - a sesquiterpenic compound from laserpitium latifolium l. root
Tetrahedron Letters No.20, pp. 1441-1446, 1965. Printed in Great Britain.
Pergamon Press Ltd.
COESTITUTION OF LASEEPITINE - A SESQUITERPFNC COMPOUED FROM LASERPITIUM LATlFOLIUM L. ROOT 111.Holub, Institute
V. Herout
of Organio
Csechoslovak
and Fe 80,
Chemistry
and Biochemistry,
Academy of Science,
Prague
and A.
Institute
Lfnek
of Solid
Czechoslovak
State
P&jsice,
Academy of Science,
Prague
(Received 11 March 1965)
In a previous I for
communication
laserpitine,
L. root.
(1)
we suggested
a compound from Iaserpitium
The carbon
dehydrogenation
of
skeleton
was proposed
some laserpltine
1,7-dimethyl.+isopropylnaphthalene
( 3) 1 (II)
o The unusual
skeleton
was,
time,
experiments
alcohol
(III)
proved
that
skeleton
(V).
and therefore
that
independent x-ray
which (2)
considered, as well,
(4) o Later has structure
Thus the structure
at new structure with
of
(daucalene
on the basis for
the sesquiterpenlc
however, IV (2,
of
there
ha8
been
5, 6) and carbon
of 6,10_dimethyl-1-isopropylblcyclo-(0,3,5)-decane
(daucane) doubtful
carotol
on the basis
1,7-dimethyl-4-isopromldecaline
dehydrogenation carotol
latifollum
derivatives
afforded
at that
structur8
of
result8
analysis
we revised
VI the carbon
carotol.
0
of laserpitine the structure
skeleton
The new structure obtained
by chemical 1441
became I and arrived
of which
corresponded
is
on
based
degradation
and
No.20
1442
I. ~=co.c
(CH~)=W .CH,
II,
From the chemical point sequence of reactions laserpltine laser01
for
of view,
elucidation
was sodium periodate
(Scheme I).
of the structure
cleavage
(‘VII) (8) which afforded
mainly di,bydroxyketo
the most important
of dihydro-
a mixture containing
aldehyde VIII and Its foneiate
This mixture was oxidized
siun pcrmanganate In alkaline
directly
acidic
on oxidation
medim yielded
IX
with potas-
medium to acid X (C14H2204,
m.p. 12C-122°C; W-s pectrum: X max 240 mu, log C The latter
of
4.17).
with potassium permanganate in succinlc
of compound X led to saturated converted
into methyl ester
according
NMRspectra
acid.
Mild hydrogenation
hydrozyketo
acid which was
C15H2604 (XI).
The compound X
contained
isopropyl
group (doublet,
1443
No.20
9.08
J = 6.4 cpe),
F,
carbon atom carrying group attached aieubetitutea
carbonyl
to carbonyl
group (8.66 9 1, methyl (7.72 r 1 conjugated
group
double bond (Wane,
16.5 cpe and quartet cpe);
methyl group bound to quaternary
in a-poeition
doublet
at 9.01 P’,
formic
6.88 C , J = 9.0 cpe).
dihydrolaeerol
that cleavage
(VII)
(cf.
group on the other;
the letter
group (canpound X1. The carboxyl
methyl group. Finally trio1
affcMed
methyl ketone,
waa in 8-position medium ia eplitt dleubetittited
the tertiary
off
group.
under formation
according
according
carbon atm
the carbowl
to hydroxyl
into
group,
hyaroxyl
carrying
group of the group of which
The latter
in alkaline
of a double bond,
to NMRepectrun;
thia corroborates
the original
bydroxyl
The presence
of methyl keto group in compound X is la
accordance of eaturated All
hydroxyketo
the facts
two dlhydrolaeerol taine
group to be secondary
aleo with the lnfra-red
ringe
the three vlclnal
-4-isopropyl previously
(and laeerpitine decaline
(11,
that one of the
and nemely that whicrh con-
hyaroxyl
seven carbon atoms. Therefore, dihydrolaserol
1356 cm”).
above Indicate
(VII)
in character.
maxima of methyl eeter
acid XI ( V
diecuesed
ta
of an aldehydio
wae then converted
to NMRspectrum 5.6 bound to quaternary
of the
Scheme I) lea&
acid on one aide (1) and to formation
carboxyl
J *
J = 9.5 cps and J = 16.5
From the above mentioned follow8 trio1
at 3.86 Q,
to the double bead ie a aarbon atom
with one proton (doublet,
viclnal
with
groups muet have at leaet
for
carbon skeleton
aa well)
of
the l,/-dimethyl-
cannot be taken ae we had aeeumed
but ae a product formed by rearrangement.
1.444
No.20
VI. R=CO.C,,
VIII. R=H IX. R-0.C.H
H,
XIII. R,=CO.$,H,Br(p) XIV. R,= H
XII.
X. J
Scheme I. As dehydrogendione of a seriee of laserpitine derivatives yieldtd, beside8 daucalene (II),
aleo a certain amount of
azulenic products, we 88811ILB that the original carbon ekeleton, like that of carotol (21, is bicycle-(0,3,5)-decane 'andthe location of ita eubetituentsfacilitate8 relative:lyeasy rearrangement into daucalene (II). On the basis of the above facts and mainly of the location of methyl groups in 00mp0ma
X, we arrived at
daucane loarbonskeleton (V) a8 the most probable one for laeerpit.ine and considering the previously reported data (1) also at complete structure VI.
1445
No.20
The x-ray analysis of p-bromobenzoyllaserol(XIII; C22H2906Br, m.po 90°C)(7) corroboratesfully thie assunption. The bromo derivative was prepared from laser01 (XIV) and p-bromobenzoylbromide; the x-ray analysis proved unambiguously structure XIII for the bromo derivative. In view of the previously reported relationshipbetween laser01 and laserpitine (1) and behavlour of the latter towards chromium trioxide (11, laserpitine has structure VI even according to x-ray analysis. The relative configurationsin the formulae follow from x-ray analysis as well (7). This work is hoped to be published in full detail in Collection of Czechoslovak Chemical Communications.
REFERENCES
1.
M. Holub, V. Herout and F. sorm, Collect. Czechoslov. ___-_____-_-_----_-_
Chem. Commun. 23, 1280 (1958). -__----_----2. V. SQkora, Lo Novotn$, M. Holub, V. Herout and F. Sorm, Collect. Czechoslov. Chem. Conrmun.26, ____________________-------------== 788 (1961). Chem. & Ind. (London), 3. F* sorm, M. Holub and V. Herout, -----------_ 1954, 965. Czechoslov. Chem Commun 4. Fe sorm, L. UrbAnek, Collect. ,,,__,_,,___,______-__,-,),,,-,-,z ;z, 420 (1948). Letters 5. V, Sykora, L. Novotnj and F. Sorm, Tetrahedron -__--___---_----_-1959, (141, 24.
No.20
14%
6.
V. Herout, 1. HO~IAU,t. Novotag, V. S$kora and P. Sorm, Chem. & Inde (London), 1960, 662. _--w-s-_---
7. A. Unek et al.: prepared for the plpes~~ 8. F. sorm, II.Bomb, V. Herout, COlleC4~_Cg~9hg~l~~: c,&&c_gg~:
$2, 135 (1954).
Pergamon Press Ltd.
COESTITUTION OF LASEEPITINE - A SESQUITERPFNC COMPOUED FROM LASERPITIUM LATlFOLIUM L. ROOT 111.Holub, Institute
V. Herout
of Organio
Csechoslovak
and Fe 80,
Chemistry
and Biochemistry,
Academy of Science,
Prague
and A.
Institute
Lfnek
of Solid
Czechoslovak
State
P&jsice,
Academy of Science,
Prague
(Received 11 March 1965)
In a previous I for
communication
laserpitine,
L. root.
(1)
we suggested
a compound from Iaserpitium
The carbon
dehydrogenation
of
skeleton
was proposed
some laserpltine
1,7-dimethyl.+isopropylnaphthalene
( 3) 1 (II)
o The unusual
skeleton
was,
time,
experiments
alcohol
(III)
proved
that
skeleton
(V).
and therefore
that
independent x-ray
which (2)
considered, as well,
(4) o Later has structure
Thus the structure
at new structure with
of
(daucalene
on the basis for
the sesquiterpenlc
however, IV (2,
of
there
ha8
been
5, 6) and carbon
of 6,10_dimethyl-1-isopropylblcyclo-(0,3,5)-decane
(daucane) doubtful
carotol
on the basis
1,7-dimethyl-4-isopromldecaline
dehydrogenation carotol
latifollum
derivatives
afforded
at that
structur8
of
result8
analysis
we revised
VI the carbon
carotol.
0
of laserpitine the structure
skeleton
The new structure obtained
by chemical 1441
became I and arrived
of which
corresponded
is
on
based
degradation
and
No.20
1442
I. ~=co.c
(CH~)=W .CH,
II,
From the chemical point sequence of reactions laserpltine laser01
for
of view,
elucidation
was sodium periodate
(Scheme I).
of the structure
cleavage
(‘VII) (8) which afforded
mainly di,bydroxyketo
the most important
of dihydro-
a mixture containing
aldehyde VIII and Its foneiate
This mixture was oxidized
siun pcrmanganate In alkaline
directly
acidic
on oxidation
medim yielded
IX
with potas-
medium to acid X (C14H2204,
m.p. 12C-122°C; W-s pectrum: X max 240 mu, log C The latter
of
4.17).
with potassium permanganate in succinlc
of compound X led to saturated converted
into methyl ester
according
NMRspectra
acid.
Mild hydrogenation
hydrozyketo
acid which was
C15H2604 (XI).
The compound X
contained
isopropyl
group (doublet,
1443
No.20
9.08
J = 6.4 cpe),
F,
carbon atom carrying group attached aieubetitutea
carbonyl
to carbonyl
group (8.66 9 1, methyl (7.72 r 1 conjugated
group
double bond (Wane,
16.5 cpe and quartet cpe);
methyl group bound to quaternary
in a-poeition
doublet
at 9.01 P’,
formic
6.88 C , J = 9.0 cpe).
dihydrolaeerol
that cleavage
(VII)
(cf.
group on the other;
the letter
group (canpound X1. The carboxyl
methyl group. Finally trio1
affcMed
methyl ketone,
waa in 8-position medium ia eplitt dleubetittited
the tertiary
off
group.
under formation
according
according
carbon atm
the carbowl
to hydroxyl
into
group,
hyaroxyl
carrying
group of the group of which
The latter
in alkaline
of a double bond,
to NMRepectrun;
thia corroborates
the original
bydroxyl
The presence
of methyl keto group in compound X is la
accordance of eaturated All
hydroxyketo
the facts
two dlhydrolaeerol taine
group to be secondary
aleo with the lnfra-red
ringe
the three vlclnal
-4-isopropyl previously
(and laeerpitine decaline
(11,
that one of the
and nemely that whicrh con-
hyaroxyl
seven carbon atoms. Therefore, dihydrolaserol
1356 cm”).
above Indicate
(VII)
in character.
maxima of methyl eeter
acid XI ( V
diecuesed
ta
of an aldehydio
wae then converted
to NMRspectrum 5.6 bound to quaternary
of the
Scheme I) lea&
acid on one aide (1) and to formation
carboxyl
J *
J = 9.5 cps and J = 16.5
From the above mentioned follow8 trio1
at 3.86 Q,
to the double bead ie a aarbon atom
with one proton (doublet,
viclnal
with
groups muet have at leaet
for
carbon skeleton
aa well)
of
the l,/-dimethyl-
cannot be taken ae we had aeeumed
but ae a product formed by rearrangement.
1.444
No.20
VI. R=CO.C,,
VIII. R=H IX. R-0.C.H
H,
XIII. R,=CO.$,H,Br(p) XIV. R,= H
XII.
X. J
Scheme I. As dehydrogendione of a seriee of laserpitine derivatives yieldtd, beside8 daucalene (II),
aleo a certain amount of
azulenic products, we 88811ILB that the original carbon ekeleton, like that of carotol (21, is bicycle-(0,3,5)-decane 'andthe location of ita eubetituentsfacilitate8 relative:lyeasy rearrangement into daucalene (II). On the basis of the above facts and mainly of the location of methyl groups in 00mp0ma
X, we arrived at
daucane loarbonskeleton (V) a8 the most probable one for laeerpit.ine and considering the previously reported data (1) also at complete structure VI.
1445
No.20
The x-ray analysis of p-bromobenzoyllaserol(XIII; C22H2906Br, m.po 90°C)(7) corroboratesfully thie assunption. The bromo derivative was prepared from laser01 (XIV) and p-bromobenzoylbromide; the x-ray analysis proved unambiguously structure XIII for the bromo derivative. In view of the previously reported relationshipbetween laser01 and laserpitine (1) and behavlour of the latter towards chromium trioxide (11, laserpitine has structure VI even according to x-ray analysis. The relative configurationsin the formulae follow from x-ray analysis as well (7). This work is hoped to be published in full detail in Collection of Czechoslovak Chemical Communications.
REFERENCES
1.
M. Holub, V. Herout and F. sorm, Collect. Czechoslov. ___-_____-_-_----_-_
Chem. Commun. 23, 1280 (1958). -__----_----2. V. SQkora, Lo Novotn$, M. Holub, V. Herout and F. Sorm, Collect. Czechoslov. Chem. Conrmun.26, ____________________-------------== 788 (1961). Chem. & Ind. (London), 3. F* sorm, M. Holub and V. Herout, -----------_ 1954, 965. Czechoslov. Chem Commun 4. Fe sorm, L. UrbAnek, Collect. ,,,__,_,,___,______-__,-,),,,-,-,z ;z, 420 (1948). Letters 5. V, Sykora, L. Novotnj and F. Sorm, Tetrahedron -__--___---_----_-1959, (141, 24.
No.20
14%
6.
V. Herout, 1. HO~IAU,t. Novotag, V. S$kora and P. Sorm, Chem. & Inde (London), 1960, 662. _--w-s-_---
7. A. Unek et al.: prepared for the plpes~~ 8. F. sorm, II.Bomb, V. Herout, COlleC4~_Cg~9hg~l~~: c,&&c_gg~:
$2, 135 (1954).