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Anionic Cycloaddition on Electron-Deficient AlkynesЦSynthesis and Stereochemistry of 3-Pyrroline-3-carboxylic Acid N N-Dimethylamides.

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N(CH,), groups (6=3.28 and 3.37 as well as 3.63 and 3.8)
in the ratio 1 :4. The most intense low-field signals can be
assigned to the 0-acylated product (4), whereas the highfield signals are most probably due to (3). On hydrolysis,
the educt ( l a ) was quantitatively regenerated from the mixture.
into 1-dimethylaminoalkenyl trifluoromethylsulfonates (5)
which directly ionize to the corresponding keteneiminium
salts. Indeed we found no spectroscopic evidence for the
presence of substantial amounts of (5) while, in certain
cases, the presence of (6) could be inferred from an IR
band around 2020 cm-’.
Under these conditions, both “aldo” and “keto” keteneiminium salts (6) reacted smoothly with olefins. The
method also enables the cyclobutenones (16) and (17) to be
prepared from ( I ) and diphenylacetylene. Yields of pure
products are generally good. In this respect, the compounds (6) are superior to the corresponding ketenes
which react only sluggishly with unactivated alkenes or alkynes.
The method described here is thus in general highly suitable for the synthesis of cyclobutanones and cyclobutenones from readily available educts.
When the acylation of ( I ) with (2) was conducted in the
presence of collidine and an olefin, [2+2] cycloadducts
were formed which were directly hydrolyzed to the corresponding cyclobutanones (7)-(15) (Table l)14]. We propose
that collidine converts the 0-acylated intermediates (4)
A 100 mL round-bottomed flask fitted with gas inlet (dry
argon atmosphere), dropping funnel and reflux condenser
connected to a sulfuric acid trap, is charged with (lb) (252
mg, 2.5 mmol), collidine (367 mg, 3 mmol), cyclohexene (4
mL) and CHC13 (10 mL). A solution of (2) (0.5 mL, 3
mmol) in 20 mL of CHCl3 is added to the refluxing mixture over a period of 24 h. Evaporation of the solvent
leaves an oil which is washed with ether (3 x 20 mL), and
then hydrolyzed overnight in a two phase system (20 mL
CH,Cl, 20 mL H20). Evaporation of CH,Cl, and extraction of the aqueous phase with cc14gives (15) which is
chromatographed on silica gel (ethyIacetate/petroleum
ether 1 :5). Yield: 165 mg (48%).
Received: May 4, 1981 [Z 865 IE]
German version: Angew. Chem. 93, 926 (1981)
Table 1. Preparation of cyclobutanones and cyclobutenones by reaction of (I)
with alkenes or alkynes.
[%I [a1
CAS Registry numbers:
(laj, 21678-37-5; (Ibj, 758-96-3; (lc). 18925-69-4;(Id), 127-19-5; (7). 4056-875 ; cis-(8). 79028-17-4; trans-(8). 79028-18-5; (9j, 79028-19-6; (10). 52784-31-3;
( I I j isomer 1, 54276-00-5; (11) isomer 2, 54235-95-9; (12). 73788-97-3; (13).
13756-54-2; (14). 42436-86-2; (15), 63903-17-3; (16). 79028-20-9; (17). 6949060-4; styrene, 100-42-5; cyclopentene, 142-29-0; ethylene, 74-85-1; cyclohexene, 110-83-8; diphenylacetylene, 501-65-5
Styrene + ( l b )
Styrene +(ldj
(2 isomers)
1760 p]
Cyclopentene +(I61
Cyclopentene (Ic)
Ethylene +(Ic)
Cyclohexene + (16)
[I] a) J. Marchand-Brynaer?,L. Ghosez, J. Amer. Chem. SOC.1972, 94, 2870;
A. Sidani. J . Marchand-Brynaert, L. Chaser, Angew. Chem. 86, 272
(1974); Angew. Chem. Int. Ed. Engl. 13. 267 (1974); H . 4 . Heine, W.
Harrmann, ibid. 93, 805 (1981); 20, 782 (1981); C. Hoornaert, A. M. Frisque-Hesbain, L. Ghosez, ibid. 87, 552 (1975); 14. 569 (1975).
[2] L. Ghosez, J . Marchand-Brynaer?,Adv. Org. Chem. 9,421 (1976); L. Ghasez, M. J. O’Donnell in A. P. Marchand, R. E. LPhr: Pericyclic Reactions
Vol. 2, Academic Press, New York 1977.
I31 M. Hourekie, M. Demuylder. L. Ghosez, unpublished results.
[4] All the new compounds gave correct analyses and characteristic spectra.
(2 isomers)
1785 [c]
Anionic Cycloaddition on Electron-Deficient
Alkynes-Synthesis and Stereochemistry of
3-Pyrroline-3-carboxylicAcid N,N-Dimethylamides
By Liliane Vo Quang, Henri Gaessler, and
Yen Vo Quang“]
1,3-Diphenyl-2-azaallyllithium(2)I’I reacts with alkynes
to give quantitative yields of 3-pyrroline~~~’.
Studying the
+( l b )
Diphenylacetylene +(lc)
[*] Dr. Y. Vo Quang, Dipl.-Ing. H. Caessler, Dr. L. Vo Quang
Laboratoire de Recherches de Chimie Oreaniaue
Ecole Nationale Superieure de Chimie de Paris
11, rue Pierre-et-Marie-Curie, 75231 Paris Cedex 05 (France)
[a] The yield was not optimized. [b] In CHCI,. [c] In CH2C12.
0 Verlag Chemie GmbH. 6940 Weinheim. 1981
0570-0833/81/1010-0880 $02.50/0
Angew. Chem. Inl. Ed. Engl. 20 (f981)No. 10
generality of this anionic polar cycloaddition with activated triple bonds, we have now found that reaction of (2)
with phenylpropiolic acid N, N-dimethylamide (3) affords
2,4,5-triphenyl-3-pyrroline-3-carboxylicacid N,N-dimethylamide ( 4 4 , thus indicating that electron-withdrawing
for anionic cycloaddition.
groups are not
The present synthetic procedure should be valuable in
the stereospecific preparation of substituted 3-pyrrolines
which are relatively rare in spite of the promising biological properties of some representative examples[*]. Using
this procedure we have also prepared 3-diphenylphosphino-2,4,5-triphenyl-3-pyrroline (31% yield; 'H-NMR:
6=5.72 (d, H-2), 5.24 (d, H-5; 52.5~4.5Hz)).
Received: December 22, 1980 [Z 875 IE]
German version: Angew. Chem. 93, 922 (1981)
CAS Registry numbers:
(I). 37019-82-2; (3). 26218-50-8; (4a), 79084-04-1 ; (4b). 79084-05-2; ( 5 ~ ) .
79084-06-3; (5b). 79084-07-4; 3-diphenylphosphino-2,4,5-triphenyl-3-pyrroline, 79084-08-5
(4h), R
(Sa),R = H
(Sb), R = C H z P h
[I] T. Kauffmann. Angew. Chem. 86. 715 (1974); Angew. Chem. Int. Ed.
Engl. 13. 627 (1974), and references cited therein.
[21 L. Vo Quang, Y. Vo Quang, Tetrahedron Lett. 1978, 4679.
[3] a) T. Kauffmann, H . Ahlers, A. Hamsen, H . Schulz, H.-J. Tilhard. A. Vahrenhorst, Angew. Chem. 89, 107 (1977); Angew. Chem. Int. Ed. Engl. 16,
119 (1977); b) S. Sinbandhit, X Hamelin, J. Chem. Soc. Chem. Commun.
1977. 768.
141 All compounds gave characteristic spectra.
151 R . K . Hill, T. Chan, Tetrahedron 21. 2015 (1965).
161 G. C i g n a r e k A . Vigeuuni, Gazz. Chim. Ital. 98. 1474 (1968).
[7] T. 1.Batterham, N . V. Riggs, A . V. Robertson, W.R. J. Simpson, Aust. J.
Chem. 22, 725 (1969).
[81 A. R . Mattocks, J. Chem. SOC.Perkin Trans. I 1978, 896.
Ring opening of N-Iithiated cis-2,3-diphenylaziridine
(l)"]occurs easily in boiling tetrahydrofuran under argon
atmosphere. The anion (2) which is formed can be trapped
at -70°C by slow addition of an equimolar amount of the
alkyne (3). After complete conversion (5 h, monitored
~ be isoNMR spectroscopically), the pyrroline ( 4 ~ ) "can
lated from the hydrolyzed mixture in 46% yield. (4a) is very
readily oxidized by air to its corresponding pyrrole derivative (5a), partially during subsequent work-up at room
temperature in either day-light or darkness, and completely in a chloroform solution in a few hours. From the
mixture of cycloadducts, the pyrrole (Sa) (22% yield) and a
polymeric pyrrole (20% yield, mass spectrometric confirmation) are also isolated.
Using the method of Hill and Chan['l it could be shown
that the 3-pyrroline (4a) is trans-configurated with respect
to C-2 and C-5: as a result of the lack of a plane of symmetry in identically a&-trans-disubstituted heterocyclic amines, the methylene protons of their N-benzyl derivatives
are stereochemically and magnetically non-equivalent. The
same observation was made in the case of 1,3-isoindolinedicarboxylic acid dimethyl ester[61.
When treated with an equimolar amount of benzyl
bromide before hydrolysis, the crude cycloadduct mixture
affords 1-benzyl-2,4,5-triphenyl-3-pyrroline-3-carboxylic
acid N,N-dimethylamide (46) in 20% yield, which is rapidly
oxidized by air to the corresponding pyrrole (Sb). Its 'HNMR spectrum shows unambiguously a stereochemically
pure trans-2,5 configuration (4b) (Table 1). The large valcoupling constants in (4a) and (4b) are
ues observed for J2,5
noteworthy, and are of the same order of magnitude as
those previously reported for compounds of this type"].
Table I. 'H-NMR data of (4) and (5) (6 values, referred to TMS).
Cpd. R
(4a) 2.40(s)
f4b) 3.82(d),3.34(d)P]
(So) 9.4(s)
2.15(~),2.70(s) CDCl,
5.74(d)[a] 5.88(d)[al 1.87(~),2.46(s) C6D6
5.62(d)[a] 5.56(d)[a] 2.34(~),2.69(s) C6D6
2.52(~),2.82(s) CDCl,
2.55(~),2.79(s) CDCI,
(Sb) 5.11(s)
Inl. Ed. Engl 20
By Dieter Reinehr and Tammo Winklerl']
5-Amino-2,4-pentadienal ( I ) , the parent compound of a
preparatively important class of compounds['1, has so far
never been isolated. (1) is formed during the photohydrolysis of pyridine""]; it is rather unstable"] and readily loses
water to give pyridine again. (1) has been characterized
only by its UV spectrum and by trapping reactions'']. We
report here on a simple synthesis of ( l ) , its isolation as a
crystalline compound, and on its spectroscopic properties.
( Ihl
Reaction of isopropylamine with the 7-pheny l-6-aza2,4,6-heptatrienal @), which is readily accessible from pyridinef3],affords (1) in 62% yield. The amine (1) is formally
replaced by isopropylamine; (I) precipitates as yellow
crystals which rapidly turn brownish at room temperature
and on exposure to air. N-Benzylideneisopropylamine (3)
was isolated from the mother liquor in 58% yield.
and (3) were characterized by their 'H-NMR and
IR spectra and elemental analyses and, in the case of ( I )
also by its I3C-NMR, UV, and mass spectra (Table I). The
UV data of (1) are consistent with those of the photohydrolysis product of pyridine['"]. The absorption maximum of a
['I Dr. D. Reinehr, Dr. T. Winkler
[a] J2.5=5.6Hz. P] J = 14.2 Hz.
(E,E)-5-Amino-2,4-pentadienal: The First
Preparative Synthesis of Hydrolyzed Pyridine
Ciba-Geigy AG, CH-4002 Base1 (Switzerland)
(1981) No. 10
0 Veriag Chemie GmbH, 6940 Weinheim. 1981
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acid, pyrroline, cycloadditions, deficiency, anionic, alkynesцsynthesis, carboxylic, dimethylamides, electro, stereochemistry
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