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New Two-stage Synthesis of the Yohimbane Ring System.

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(a), R
(b), R
M. p. ("C)
I values [bl
21 7-2 18
147-148 (dec.)
184-1 85
215 [21
316 [71
226 [21
185 [81
(dec.) [41
fa] The structure of the products is confirmed by satisfactory elemental
analysis, IR, UV, and N M R measurements.
[bl These values are the highest ones reported in the literature
Oxidation of 2,4,6-tert-butylphenol (7b) by silver carbonatel
Celite in benzene under nitrogen gives a deep blue solution
of the stable radical (86). In the presence of oxygen, (8b)
affords the peroxide (9b)in high yield.
I t is expected that the easy preparation of the reagentI31,
the simplicity of the oxidizing procedure, and the high purity
of the final products will lead to further applications of the
silver carbonate/Celite reagent in oxidative coupling of
30 g of purified celite[**J i s added to a mechanically stirred
solution of 34 g (200mmoles) of silver nitrate in 200 ml
distilled water.
A solution of 30 g (105 mmoles) Na2CO3 . 10 HzO [or 21 g
(210 mmoles) of KHC031 in 300 ml distilled water is then
added slowly to the resulting homogeneous suspension.
When the addition is complete, stirring is continued for a
further 10 minutes. The yellow-green precipitate which is
formed is then filtered off, washed with distilled water until
neutral, and finally dried in a rotary evaporator over a period
of several hours. The silver carbonate/celite reagent contains
about 1 mmole Ag2C03/0.57 g.
2.6-Dimethylphenol (1.2 g) was refluxed for 30 minutes in
benzene (150 ml) with silver carbonate/Celite reagent (25.1 8).
Removal of the solid phase and evaporation of benzene
leaves 1.16 g (98 %) ofpracticallypure (20) (m.p.217--218 "C).
Recrystallization does not raise the melting point.
[l] W. I.Tuylor and A . R . Battersby: Oxidative Coupling of
Phenols. M. Dekker, New York 1967.
121 K . von Auwers and T . von Markovits, Ber. dtsch. chem. Ges.
38, 226 (1905); K . von Auwers and G. Wittig, ibid. 57, 1270 (1924);
C. Walling and R. B. Hadgdon, J. Amer. chem. SOC.80, 228
(1958); E. C . Horswill and K . U.Ingold, Canad. J. Chem. 44, 263
(1966); R . G . R . Bacon and A . R . h a t , J. chem. SOC.(London)
C 1966, 791.
[3] M . Fetizon and M. Golfer, C. R. hebd. Seances Acad. Sci.
267, 900 (1968).
[4] C. D. Cook, J. org. Chemistry 18,261 (1953).
[5] H. Hart and F. A . Cassis j r . , J. Amer. chem. SOC.73, 3179
[6] K . Fries and E. Brundes, Liebigs Ann. Chem. 542, 48 (1939).
[7] R . H. Bauer and G. H . Coppinger, Tetrahedron 19, 1201
[8] M. S. Kharasch and B. S . Josh;, J. org. Chemistry 22, 1439
[**I The ceiite was purified by washing it successively with
methanol containing 10% Conc. HC1 and then with distilled
water until neutral ; it was finally dried at 120" C.
New Two-stage Synthesis of the Yohimbane Ring
By W. Meise and F. Zymalkowski[*]
We recently prepared a Berberis alkaloid, (+)-xylopinine, in
a simple two-stage synthesis from homoveratrylamine and
[21. The ring system of
yohimbane can be built up in the same way.
Nb-Methyltryptamine ( I ) and isochroman-3-one (2) give a
92 % yield of N-[2-(l-methyl-3-indolyl)ethyl]-o-(hydroxymethy1)phenylacetamide (3), which affords 1-[2-(chloromsthyl)benzyl]-3,4-dihydro-9-methyl-P-carboline( 4 ) by a
Bischler-Napieralski reaction with phosphorus oxychloride.
If ( 4 ) is isolated by the usual methods, by-products are formed whose separation is difficult and involves losses. These
Received: March 24, 1969
[Z 974 IE]
German version: Angew. Chem. 81, 423 (1969)
[*I Dr.
V. Balogh, Prof. Dr. M. Fetizon, and Dr. M. Golfier
Universite de Paris, Laboratoire de Stereochimie,
Faculte des Sciences
91-Orsay (France)
Angew. Chem.internat. Edit.
1 Vol. 8 (1969) J No. 6
side reactions are, however, avoided if crude ( 4 ) is dissolved
in methanol and treated directly with NaBH4; under these
conditions reduction of the C = N double bond and ringclosure to the benz[g]indolo[2.3-a]quinolizine derivative ( 5 )
occur. The melting point of the base and its picrate, as well
as the UV, IR, and N M R spectra, accord with expectation;
distillation and purification by way of the picrate are unnecessary in this process [3941.
The synthesis can be applied also to tryptamine and to its
derivatives with substituents in the benzene ring; use of substituted isochromanones gives a simple method of preparing
alkaloids of yohimbane type.
1 I i1 1 1 1
C O Z C ~ H S [a1
Ial M.P. of an inseparable mixture of (4ba') (70%) and an unknown substance
(30 %) is 81-99 O C (proportions determined by N M R spectroscopy).
2.0 Hz), the methylene protons on C-1 as a doublet (6 =
3.86 ppm) with the coupling constant 3J = 2.0 Hz typical of
indenes; the ester protons appear at 4.59 ppm (q, 3J= 7.5 Hz)
and at 1.46 ppm (t, 3 3 = 7.5 Hz).in the ratio 10:1:2:2:3. The
structure is further proved by degradation of (4aa') by hydrogenation. hydrolysis, and decarboxylation to the known 3phenylbenz[e]indane [41.
On photolysis (Philips HPK 125-W high-pressure lamp) of
(Ib) in (2b'). the dimethyl 2,3,4,5-tetraphenyl-2,4-cyclopentadienespiro-2'-cyclopropene-2',3'-dicarboxylate
postulated as intermediate could be isolated by chromatography in CHC13 on silica gel as red crystals, m.p. 143-144 "C,
in 31% yield. Typical for (3bb') was the N M R spectrum
which indicated a highly symmetrical molecule with 6 =3.78
ppm (6H, s) and 6.9-7.3 ppm (20H, m) also the cyclopropene hands at 1865 cm-1 and the molecular ion at mje =
8.7 g (50 mmoles) of ( I ) and 8.9 g (60 mmoles) of (2) are
boiled under reflux in 50 ml of ethanol for 18 h. 14.2 g of ( 3 ) .
having m.p. 151-153 "C, crystallizes from the solution and a
further 0.65 g (total yield 92%) is obtained on concentration
of the mother-liquors. The product is recrystallized from
ethanol, giving colorless needles of m.p. 153-154 "C.
3.22 g (10 mmoles) of ( 3 ) is boiled under reflux with 30 g
of phosphorus oxychloride for 2 h, then cooled and treated
with 50 ml of light petroleum; ( 4 ) separates as an oil. The
upper layer is decanted and the crude ( 4 ) is digested five
times with light petroleum (50-ml batches) and taken up at
once in methanol (50 ml). This solution is treated with 5 g of
NaBH4 during 1.5 h, with stirring and cooling in ice, and
then boiled for 0.5 h under reflux. Next the methanol is
removed in a vacuum and the residue is suspended in 50 ml
of water and shaken out with five portions, each 50 ml, of
chloroform. Material recovered on evaporation of the organic phase solidified when kept. Rubbing this with 5 ml of
methanol, collecting it, and washing it with a total of 10 ml
of methanol gave 2.00 g of IS), m.p. 133-135 'C; adding
water to the filtrate gives an additional 0.25 g (total 78 %).
N M R (CDC13; T M S as internal standard): T = 5.95 (2H on
C-21, s); 6.30 (N-CH3, s).
Received: March 31. 1969
12 977 1El
German version: Angew. Chem. 81, 425 (1969)
[*I Dr. W. Meise and Prof. Dr. F. Zymalkowski
Pharmazeutisches Institut der Universitat
53 Bonn, Kreuzbergweg 26 (Germany)
11J This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
[2] W. Meiseand F.Zyrnalkowski,Tetrahedron Letters, I969,1475.
[31 P. L. Julian and A . Magnani, J. Amer. chem. SOC.71, 3207
[4] K . T. Potts and Sir R. Robinson, J. chem. Sac. (London)
1955, 2675.
Formation of Benzindenes on Photolysis of Phenylsubstituted Diazocyclopentadienes in Alkynestll
By H. Durr and L. Schrader[*l
Photolysis of substituted diazocyclopentadienes ( I ) in benzene 121 to give benzocycloheptenes or cyclopentacyclooctenes
made it of interest to study the photolysis of ( I ) in alkynes.
If phenyl-substituted diazo-compounds ( I ) are photolyzed
in ethyl propiolate (2a') or in dimethyl acetylenedicarboxylate (26'). the carbenes formed from (1) react in participation with the phenyl substituents. The benzindenes ( 4 ) are
thus formed in moderate yield from 5-diazo-1 .Cdiphenyl( l a ) and 5-diazo-l,2,3,4-tetraphenyl-cyclopentadiene
(Ib) [31.
The structure of the benzindenes ( 4 ) is shown in particular
by the spectra. For instance, the N M R spectrum of (4aa')
shows the signals of the aromatic protons a t 6 = 7.4-9.3ppm;
the olefinic proton at C-2 appears as a triplet (6 = 6.79 ppm,
Ethyl 3-phenylbenz[e]indene-5-carboxylate(4aa')
2.00 g (8.2 mmoles) of (la)[31 in 150 ml of (2a') were irradiated with a Philips HPK 125 H g high-pressure lamp (Pyrex
filter; 18-20 "C) until the theoretical amount of N2 had been
evolved (-1.5 h). When the ester (2a) was removed under
vacuum, yellowish-brown crystals were precipitated. The
whole residue was taken up in benzene and chromatographed
on silica gel with benzene/light petroleum (1:1;b.p. 40-80 "C).
1.20 g (47%) of (4aa'). m.p. 155-156'C. were obtained
from the eluate after recrystallization from CHZClz/methanol
IR spectrum (KBr): 1715 cm-1 (s. C=O), 1585 (m), 1495 (m),
1465 (m).
Received: March 31, 1969
[Z 978 IE]
German version Angew. Chem. 81, 426 (1969)
Dr. H. Diirr and Dip1.-Chem. L. Schrader
Institut fur Organische Chemie der Universitat
66 Saarbriicken 15 (Germany)
[I] Part 14 of Photochemistry of Small Rings. - Part 13: H.
Diirr, G . Scheppers, and L. Schrader, Chem. Commun. 1969,257.
[2] H. Diirr and G. Scheppers, Tetrahedron Letters 1968, 6059;
Angew. Chem. 80, 359 (1968); Angew. Chem. internat. Edit. 7,
371 (1968).
[3] B. Eistert, M . Regitz, G. Heck, and H . Schwall, in HoubenWeyl: Methoden der organischen Chemie. 4th Edit. Vol. X/4,
p. 475ff,, G. Thieme Verlag, Stuttgart 1968.
[4] R. Granger and H. Ormlesi, C.R. hebd. Seances Acad. Sci.
246, 779 (1958); Bull. SOC.chim. France 1958, 986.
A New Benzocyclopropene Synthesis
By H . Diirr and L. Schrader[*l
The photolysis of phenyl-substituted diazocyclopentadienes
in dimethyl acetylenedicarboxylate affords benzindenes 121
via the corresponding spirocyclopropenes. Our interest lay in
establishing whether photolysis of the spiro-3H-pyrazoles
(Ia)-(lc) 131, which are formed by 1,3-dipolar addition of
Angew. Chem. internat. Edit. J Vol. 8 (1969)J No. 6
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