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Condensation of Alkynylamines with 1 3-Dipolar Compounds Carbonyl Compounds and Schiff Bases.

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Table 3. Acrylamidines formed from ynamines.
Condensation of Alkynylamines with lY3-Dipolar
Compounds, Carbonyl Compounds
and Schiff Bases [I1
+
R'-C=C-N(CH&
C6H5-CH=N-R2
By Dr. R. Fuks, Dr. R. Buijle, and Dr. H. G. Viehe
Union Carbide European Research Associates,
Brussels (Belgium)
Only two examples of cycloaddition to ynamines have so far
been reported 121. By 1,3-dipolar cycloaddition under the
conditions described previously 131, ynamines readily afford
dialkylamino-substituted heterocycles ( I ) (Table 1). The
structure of the products follows from analytical data and in
analogy to earlier results [31.
I
zI
R2
-CoH?
C6H5t-CjHu-
Table 1. Heterocycles from ynamines.
1
II
-(CH:),-CH,
-c62i
87-88
140/0.3
145/0.1
[a] See footnote to Table 2.
Received: April 7th, 1966
[Z 194/29 IEI
Publication delayed at the authors' request
Germin version: Angew. Chem. 78, 594 (1966)
.
R
R'
1
180
59
151
95
144
89
128
63
143
71
144
45
Ynamines condense surprisingly easily also with aldehydes
and ketones. Although this addition occurs without catalysis
when the components are heatedc41, catalysis with 1 to
5 mole- % of boron trifluoride-ether is preferable.
Addition of this catalyst t o a n etheral solution of eqnivalent
amounts of the reactants leads t o exothermal condensation
that is usually complete in a few minutes but at latest after
refluxing for half an hour.
The four-membered ring system (2) probably formed as
intermediate rearranges to the a,P-unsaturated carboxamides
(3).
BF3-catalysed addition of Schiff bases to ynamines occurs
less easily and gives lower yields. Reaction times are about
24 hr under the conditions described for thz carbonyl
compounds (heating under reflux). Acrylamidines (S), whose
structures are proved by independent syntheses, are obtained,
probably by way of azetines ( 4 ) .
[l] Part XI11 of Hetero-substituted Acetylenes. - Part XII:
R . Buijle, A . Halleux, and H . G. Viehe, Angew. Chem. 78, 593
(1966); Angew. Chem. internat. Edit. 5 , 584 (1966).
[ 2 ] H . G. Viehe, R . Fuks, and M . Reinstein, Angew. Chem. 76,
571 (1964); Angew. Chem. internat. Edit. 3, 581 (1964); H. Ficini
and C . Barabara, Bull. SOC.chim. France 1964, 871; 1965, 2787;
see also M . Frmck-Neumann, Tetrahedron Letters 1966, 341.
[3] R. Huisgen, Angew. Chem. 75, 604 (1963), Angew. Chem.
internat. Edit. 2, 565 (1963).
[4] Stoichiometric amounts of this condensing azent were
necessary in similar addition reactions: H . J . T. Bos and J . F.
Arens, Recueii Trav. chim. Pays-Bas 82, 845 (1963).
Chlorination of Cyclooctatetraene
By Prof. Dr. R. Huisgen, Dr. G . Boche,
Dipl.-Chem. W. Hechtl, and H. Huber
Institut fur Organische Chemie
der Universitat Munchen (Germany)
W . Reppe et al. [ I ] obtained the bicyclic cis-dichloride (2)
from cyclooctatetraene and chlorine or sulfuryl chloride 121.
Studies on Diels-Alder adducts by C . D . Nenitzescu et a/. '31
strongly suggest the trans-structure ( 4 ) for a dichloride
formed from (2) under the influence of heat or acid catalysis.
This chlorination was found to follow a similar course as
bromination [41. Four isomeric dichlorides can be isolated in
pure, crystalline form. Rapid stereospecific cis-addition of
chlorine, yielding the isomer ( I ) , is observed in both polar
(acetonitrile) and nonpolar solvents (hexane).
Table 2. ?,S-Unsaturated carboxamides formed from ynamines
COzH
H - CI - C 1
H - CI- C 1
CO z H
o;l-
13)
84--55 [a]
106--107 [a]
56-57
65-66
75-76
70-71
@c1
H H
(4)
82
84
83
90
72
85
[a] Melting point and yield of the cis-isomer for.ned exclusively
Angew. Chem. internat. Edit.
H
Vol. S (1966) / No. 6
According to the N M R spectrum, cis-7,8-dichloro-l,3,5-cyclooctatriene ( I ) arises quantitatively as primary product on
low-temperature chlorination and can be isolated by crystallization at 0 ° C (m.p. 34'62; 91 % yield). Ozonolysis in ethyl
acetate gives 67 % of meso-dichlorosuccinic acid. The 1HN M R spectrum of ( I ) in CC14 includes bands at 4.09 (s)
585
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