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Models for the Bisynthesis of Naturally Occurring Divinylcyclopropanes and Cycloheptadienes.

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In particular, the fact that structurally similar w-phenyl-analogous polyenoic acids of the vitamin A series display anti-tumor activity[41prompted us to undertake the total synthesis
of flexirubin dimethyl ether (2).
Starting from 4-metho~y-3-rnethylbenzaldehyde[~]
( 3 ) , Wittig reaction with the phosphonium salt prepared from ethyl
y-bromocrotonate[61initially gave the pentadienoic ester ( 4 )
[m.p. 92-94°C; lit.'51 91-93"C] which was transformed by
reduction (LiAlH4)and oxidation (MnOz) into the aldehyde
( 5 ) [m.p. 69-70°C; A,, 354 nm (EtOH)]. A second Wittig
reaction with the phosphonium salt (6) derived from l-bromo2-penten-4-yne (from 2-penten-4-yn-I-01"' and Ph3PBr2)provides access to the decatetraenyne (7) [m.p. 76-79°C; M +
250.1365; i
,
,
,
370 nm (hexane)] which we have converted
by Chodkiewicz coupling with (8) (from penten-4-yn-1-01
and NaOBr) into the diyne (9) [m.p. 158-163°C; M +
330.1617; A,, 397 nm (hexane); 'H-NMR (180 MHz): 6=2.22
ppm (3H, s), 3.83 (3H, s), 4.2 (2H, br), 5.5-7.5 (13H, m)].
C H3 0& H o
-
[l] H. Reichenbach, H. Kleinig, H. Achenbach, Arch. Microbiol. 101, 131
(1974).
[2] H.Achenbach, W Kohl, H.Reichenbach, Arch. Microbiol., in press.
[3] a) H. Achenbach, W Kohl, H. Reichenbach, Tetrahedron Lett. 1974,
2555; b) Chem. Ber. 109, 2490 (1976); c) Justus Liebigs Ann. Chem.
1977, 1.
[4] W Bollag, H.Ruegg, G. Ryser, DOS 2.414.619; Chem. Abstr. 82, 111778
(1975).
[5] A . Barns, N . Gerber, J. Org. Chem. 26, 4540 (1961).
[6] f.Bohlmann, Chem. Ber. 90, 1519 (1957).
[7] L. J. Haynes, I . Heilbron, E. R . H . Jones, F. Sondheimer, 3. Chem.
Soc. 1947, 1583.
Models for the Biosynthesis of Naturally Occurring
Divinylcyclopropanes and Cycloheptadienes[**]
By Manfied Schneider and Angelika Erbed']
Dictyopterenes A (I) and C' (3) were isolated from the
gametes of brown algae (Dictyopteris)['].The biosynthesis of
(3) presumably proceeds via the cis-divinylcyclopropane (2),
which does not occur in nature. (I) and (2) are probably
(3)
f
( 4 ) , R = C02C2H5
(5). R = C H O
formed by introduction of a methylene group from active
methyl (S-adenosylmethionine)'Z1into the corresponding 1,3,5decatriene (from fatty acids), (2) being then converted by
Cope rearrangement into ( 3 ) under the conditions of the
biosynthesis (ca. +15"C). (I) cannot be the precursor of
(3) since it is thermally stable up to 150"C[31.
Like (I ) and (3), monosubstituted cis-divinylcyclopropanes
of type (2) ought to be readily accessible by decomposition
of suitably substituted 3,5-di~inyl-l-pyrazolines[~~.
Participation of the Cope rearrangement in the biosynthesis of (3)
could thus be studied on a model.
H,C=CH-CHN2
Wittig reaction of the aldehyde (10) [M' 328.1451; i
,
,
,
419nm (hexane)] (from ( 9 ) and MnOz) with the phosphonium
salt (If) yielded ( 1 2 ) [mixture of isomers: M + 658.4032;
A,, 411 nm (hexane)], thus completing the carbon skeleton
of flexirubin. Compound (I I ) is accessible by esterification
of bromoacetic acid with the sodium salt of the previously
described compound 2-dodecyl-3-methoxy-5-methylphenoIr3b1
and subsequent reaction with triphenylphosphane. Catalytic
+
+4T
R
-H
H
/-.y-p+R+
N=N
( 4 c ) , R = nBu
R = CH,
(Sc),
H
H
A y - y - - w R
N=N
(41).
R = nBu
(51). R = CH,
The 1,3-dipolarcycloaddition of 3-diazo-1-propeneto trans1,3-0ctadiene[~]
affords the cis- and trans-3-(trans-l-hexenyl)-5-
H25C~0CH3
hydrogenation of (I 2) over a Lindlar catalyst and isomerization with iodine led to (2)[3b1.
Received: January 11, 1977 [Z 647 IE]
German version: Angew. Chem. 89, 198 (1977)
CAS Registry numbers:
( 2 ) , 60488-42-8; ( 3 ) , 32723-67-4; (4), 61665-55-2; (S), 61665-56-3; ( 6 ) ,
61665-57-4;(7),61665-58-5;(8),5255t-93-6;
(9),61665-59-6; ( l o ) , 61665-609; (I I), 61665-61-0; ( 1 2 ) , 61665-62-1; ethyl y-bromocrotonate, 6065-32-3;
2-penten-Cyn-t-01, 5557-88-0
192
vinyl-I-pyrazolines ( 4 c) and ( 4 t ) . The cis- and trans-3-(transl-propenyl)-5-vinyl-l-pyrazolines( 5 c) and ( 5 t ) are formed
[*I
Dr. M. Schneider, A. Erben
Institut fur Chemie der Universitat Hohenheirn
Postfach 106, 7000 Stuttgart 70 (Germany)
We thank Dr. W Pickenhagen (Firmenich & Cie., Geneva) for the
spectra of ( I ) and (3).-This work was supported by the Deutsche
Forschungsgemeinschaft.
r*]
Angew. Chem. I n t . Ed. Engl. 16 (1977) N o . 3
analogously by addition to trans-I ,3-pentadiene. The cycloaddition proceeds exclusively as shown below, affording the
1 -pyrazolines in the isomeric ratio 1 : 1 (NMR integration).
( 4 c j and ( 4 t) decompose thermally ( 3 G 6 0 " C )and photochemically ( O T , n-pentane, Pyrex filter, Hanau T Q 150) with
formation of trans-l-(trans-l-hexenyl)-2-vinylcyclopropane
( I j and 6-butyl-1,4-cycloheptadiene (3 j . trans-I-(trans-1 -Propenyl)-2-~inylcyclopropane
( I a j and 6-methyl-I ,4-cycloheptadiene ( 3 u ) are obtained in an analogous way from (512)
and ( 5 t ) .
(4c) + (41)
A, hv
N,- ( 1 )
A
hv
f
41.5%
55.57'0
(2)
-
(3)
[ I ] L. Jarnicke, D . G . Muller, Fortschr. Chem. Org. Naturst. 30, 61 (1973).
[2] J. ff. Law, Acc. Chem. Res. 4, 199 (1971).
[3] The transformation can be achieved photochemically only by photosensitized irradiation with short-wave UV: W Pickenhagen, F . Nbf; G . Ohloff.
P . Muller, J.-C. Perlberger, Helv. Chim. Acta 56, 1868 (1973).
[4] M . Schneider, J . Rebell, J. Chem. SOC. Chem. Commun. 1975, 283; M .
Schneider, Angew. Chem. 87, 717 (1975); Angew. Chem. Int. Ed. Engl.
14, 707 (1975).
[S] Prepared by dehydration (KHSO+, 160°C) of 3-octen-1-01(from acrolein
and n-pentylmagnesium bromide) and subsequent fractional distillation.
Small amounts of the cis form are isomerized to the / r a m form by
I,-catalyzed irradiation.
[6] R. E. Moore, J . A . Pettus, Jr., J . Mistysyn, J . Org. Chem. 39. 2201
(1974); G. Oh/off; W Pickenhagen, Helv. Chim. Acta 5 2 , 880 (1969).
171 The irradiation was carried out directly in the NMR apparatus (Bruker
HX 90 R with modified probe) using a quartz light guide; lamp: Philips
SPIOOOW; filter UGl.
58.5%
44.5qo
Intramolecular Mobility in CS2 Complexes of Manganese[**l
By M a x Herberhold, Margot Suss-Fink, and Cornelius G.
Kreiter"]
A
hv
35%
6 570
60%
40%
All spectroscopic data of the natural products ( 1 ) and
( 3 ) , readily accessible in this way, were identical with those
of the compounds isolated and obtained by multistep synthesis[6*71.
(I a ) and (3 a ) have been unequivocally identifiedL4].
Low-temperature photolysis of ( 4 c j ( 4 t ) at -45"C'71 affords
exclusively ( 1 j and cis-I -(trans-I -hexenyl)-2-~inylcyclopropane (2). In an analogous way the low-temperature photolysis
of ( 5 c ) + ( 5 t ) leads to ( I a ) and cis-l-(trans-l-propenyl)-2vinylcyclopropane ( 2 n ) . The novel compounds ( 2 ) and (2a)
are stable for several hours up to -20°C. and rearrange
quantitatively at G 2 0 " C into the 1,4-cycloheptadienes (3)
and (3 a), respectively. Both reactions can be followed directly
by 'H-NMR spectroscopy by observing the allylic protons
of (3) (6=2.18 and 2.86 ppm) and (3a) (6=2.25 and 2.83
PPm).
+
Considerable speculation still surrounds the coordinative
bonding of carbon disulfide in transition metal complexes[']
since the structures of only few molecules are known. We
have made the surprising observation that the two cyclopentadienylmanganese complexes CpMn(C0)2(CS2) ( I ) and
[CpMn(C0)2]2(CS2)(2) give temperature-dependent NMR
spectra. Thence it is concluded that:
1) The mononuclear complex ( I ) possesses an $-coordinated CS2 ligand which undergoes hindered motion in solution.
2) The dinuclear complex (2 j contains a new kind of CSz
bridge and is a fluxional molecule.
v ( C . 0 ) 2 0 1 2 , 1 9 5 7 ern-'
(THF)
V(C-0)
2021,1969;
1 9 2 8 , 1 8 7 1 cm-' ( T H F )
Experinzental:
A solution of N-allyl-N-nitrosourea (69) in triethylene glycol (50 ml) is added dropwise with stirring at 20°C and 15
torr to a solution of sodium (69) in triethylene glycol (I00
ml). The 3-diazo-1-propene that is formed (ca. 10 mmol,
0.7 g) is condensed at -78°C in a cold trap containing 30
mmol trans-I ,3-octadiene or -pentadiene. The resulting deepred mixture is stored at +4"C until completely decolorized
(ca. 4 days), taken up in n-pentane and washed with ice-water
to remove the pyrazole. After drying, all volatile components
are distilled off at OoC/l5 torr. The pyrazolines ( 4 c ) + ( 4 t )
(1.5 mmol) or ( 5 c) + ( 5 t) (1.4 mmol) so obtained are photolyzed at 0°C without further purification in a forced circulator
(Hanau T 150, pyrex filter) or thermolyzed in n-heptane at
30--60"C. After distillation, the products (1) and ( 3 ) , or
(la) and (3a), are isolated by gas chromatography (3 m
10% OV17 on Chromosorb W).
Received: January 17, 1977 [Z 651 1E]
German version: Angew. Chem. 89. 187 (1977)
CAS Registry numbers:
( I ) , 50265-47-9: ( I a ) , 61649-93-2; ( 2 ) , 50265-49-1; (Za), 61688-32-2: ( 3 ) .
22735-58-6; ( 3 ~ ) 61689-14-3:
.
(4c), 61649-94-3: (4t), 61688-33-3; ( j c ) .
61649-95-4; ( 5 t ) , 61688-34-4; 3-diazo-l-propane, 2032-04-4; trons-1,3-octadiene, 39491-65-1 ; rrans-1,3-pentadiene, 2004-70-8
Angew. Chem. I n t . Ed. Enql. I6 ( 1 9 7 7 ) N o . 3
Compounds ( I ) and (2) can be prepared by photolysis
of CpMn(C03) in tetrahydrofuran solution (THF) and subsequent reaction of the labile THF complex CpMn(C0)2(THF)
with CS2[21:
In solution ( I ) slowly loses CS2 to form (2). Contrary
to earlier reports[31,we were unable to observe the reverse
reaction.
The compositions of (1 j and ( 2j are confirmed by elemental
analysis and mass spectra. Their structures follow from NMR
[*I Doz. Dr. M. Herberhold, DipLChem. M. Suss-Fink, Doz. Dr. C. G.
Kreiter
Anorganisch-chemisches Institut der Technischen Universitat
Arcisstrasse 21, D-8000 Miinchen 2 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Indnstrie. M . Sliss-Fink is indebted to
the Cusanus Foundation for a graduate study grant.
193
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model, cycloheptadiene, occurring, naturally, bisynthesis, divinylcyclopropanes
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