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Erratum УFormation of Nucleophilic Carbenes from Heterocyclic N-Methyl BetainesФ.

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Synthesis of 1-Selenochromones 11)
By Dr. F. Bossert
Pharmazeutisch-Wissenschaftliche Abteilung
der Farbenfabriken Bayer AG., Werk Eiberfeld (Germany)
We have prepared 1-selenochromones ( I ) by condensation
of selenophenol and P-keto esters with polyphosphoric acid.
For example, ethyl acetoacetate yields 2-methylselenochromone ( I ) , R = CH3, m.p. 100°C, ethyl benzoylacetate yields
with water, difute sodium hydroxide, and water and thed
dried. After evaporation of the ether, the crude product is
obtained in 40-50% yield and is purified by recrystallization
from methanol, ethanol, or benzene/ligroin. The structures
of the products were proved by comparing their infrared and
N M R spectra with those of the corresponding thio compounds.
Received: August 23rd. 1965
[Z 54/880 IE]
German version: Angew. Chem. 77, 913 (1965)
[l] Cf. M . Renson, Bull. SOC.Chim. Belg. 73, 483 (1964).
ROOC
O S e H
+
Errata
R
HOF,
2-phenylselenochromone ( I ) , R = C6H5, m.p. 127-128 OC,
and ethyl 4-methoxybenzoylacetate yields 2-(p-methoxypheny1)selenochromone ( I ) , R = p-CH30CsH4, m.p. 150 to
152 ‘C.
A mixture of 0.1 mole of selenophenol and 0.12-0.14 mole
of P-keto ester is added dropwise over 1 h to 350 g of polyphosphoric acid at about 90°C, and the mixture is then
heated for about 3 h at 90- 100 “C and poured onto ice. The
product is extracted with ether, and the ether extract is washed
“Formation of Nucleophilic Carbenes from Heterocyclic NMethyl Betaines” by H. Quast and E. Frankenfeld, Angew.
Chem. internat. Edit. 4, 691 (1965):
The last line of this Communication should read “limiting
structure (2’)”.
“Synthesis of 2,5-Dibromo-l,2,4-triazoleby Bromination of
1,2,4-Triazole” by C. F. Kroger and H. Frank, Angew. Chem.
internat. Edit. 4, 434 (1965):
In the title and in the last sentence of this Communication,
the name of the compound synthesized should be changed to
“3,5-dibromo- 1,2,4-triazole”.
C O N F E R E N C E REPORTS
~~
Conference of Chemistry Lecturers in Potsdam
The Conference was held at Potsdam (Germany) on July
108 lectures
1965. The
delivered.
following is a selection of excerpts
the
5th-8th,
from
New Photochemical Reactions of Nitrogenous Steroids
F- J
-
H :n
H3c
G . Adam and K . Schreiber, Gatersleben (Germany)
Unlike
its
(22R:25S)
and
(22s: 25R)
cH3
:
H3c
(2a. b)
ib)
(4
stereoisomers,
tion
not
(22s:
lead
induced
25S)-N-chloro-22,26-imino-5a-cholestan-3~-ol
to solanidanol
by ultraviolet
in the
irradiation.
Hofmann-Loffler-Freytag
An unresolvable
( 1 ) reacmixdoes
&cH3H0&;H
ture of the two C-20 stereoisomers of 20-chloro-5a-pregnan3P-01 ( 2 4 b) is obtained instead (in 52 % yield) in a degradation reaction taking place when ( I ) is irradiated in trifluoroacetic acid. The same product has also been synthesized from
(20R)-3P-acetoxy-5a-pregnan-20-01(3).
H3 C
Ho
H
OH C 1
(4). 22s :25R
(51, 22s : 25s
H3 C
H
I7a. b)
(6). 22R: 25s
According to the free-radical mechanism postulated for this
new type of fragmentation, the nitrogen-containing radical
ion formed in the photochemical reaction undergoes C-C
cleavage via (a), the resulting carbon radical (b) being stabilized before it recombines with a chlorine radical to form
(2a,b).
Angew. Chem. internat. Edit. Vol. 4 (1965) / No, 10
When this photolysis is carried out on the 16P-hydroxy-substituted N-chloro-22,26-iminocholestanols
(4)-(6), degradation is always the principal reaction, leading invariably to the
same mixture of C-20 stereoisomeric 20-chloro-5a-pregnan3@,16P-diols(70,b) in a yield of up toSZ%.Theresultingmixture can be resolved by column chromatography.
879
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