close

Вход

Забыли?

вход по аккаунту

?

Ionization and Rearrangement of Diphenylphenoxymethylmagnesium Chloride.

код для вставкиСкачать
peptide aziridide (3) which undergoes rapid cyclization to
give ( 4 ) with simultaneous liberation of aziridine, which thus
becomes available for further reaction. This cyclization
greatly hinders polymerization which otherwise would
readily occur - particularly in the presence of small amounts
of base. That reaction (3) proceeds rapidly can be ascribed
t o the fact that compound (3) has the character of a n activated carboxylic acid derivative.
We have been able t o support this view by the following observations: If N-trifluoroacetylphenylalaninaziridide (prepared in 72% yield, m.p. 107-108°C, by reaction of trifluoroacetylphenylalanine and aziridine by the anhydride
method) is treated with 0.2 N N a O H at room temperature in
order t o remove the trifluoroacetyl residue 121, phenylalanine
is formed exclusively; the aziridino residue, therefore, is just
as labile as the trifluoroacetyl group. Hydrolysis with semiconcentrated aqueous ammonia affords phenylalaninamide
(87 %,). Moreover, sodium ethoxide in ethanol liberates
aziridine from N-trifluoroacetylphenylalaninaziridide.
General method of preparation:
The Leuchs anhydride ( 1 ) is added in small portions (10 nig)
with vigorous stirring at room temperature to a solution of
aziridine (0.3 ml) in ethanol (or T H F ) (3 ml). The mixture is
allowed t o stand after each addition until evolution of COz
is complete and all anhydride has dissolved t o give a clear
solution; addition of anhydride is discontinued as soon as
the solution becomes turbid. After 1--5 min almost analytically pure diketopiperazine ( 4 ) crystallizes out in 70-80%,
yield. The mother liquor contains a further 1CblSX of ( 4 ) .
[Z 132 IE]
Received: September 15, 1969
German version: Angew. Chem. 82, 137 (1970)
Publication delayed a t authors' request
[*I Priv.-Doz. Dr. P. Rosenmund and Dipl.-Chem. K. Kaiser
Institut fur Organische Chemie der Universitat
6 Frankfurt/Main, Robert-Mayer-Strasse 7/9 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft.
[I] Part of Dissertation by K . Kaiser, Universitat Frankfurtl969.
[2] F. Wqvgand and R . Geiger, Chem. Ber. 89, 647 (1956).
Ionization and Rearrangement of Diphenylphenoxymethylmagnesium Chloride[**I
By H . F. Ebel, V. Dorr, and B. 0 . Wagner[*]
In earlier investigations[ll of metalated ethers and their rearrangement (Wittig rearrangement) the change of properties when going from the magnesium and zinc derivatives of
diphenylphenoxymethane, ( l a ) and ( I b ) respectively, to the
alkali metal derivatives ( I c ) was emphasized. Whereas ( l a )
and ( I b ) are colorless and do not rearrange to the triphenylmethoxides (2a) and (Zb), the alkali metal compounds ( I c )
are deep red and undergo slow conversion into (2c).
We have now found that hexamethylphosphoric acid triamide (HMPT), which has repeatedly been shown t o have
superior solvation properties for organomagnesium [2,31 and
other organometallic compounds 131 and which recently has
been called a "super-solvent" in carbanion chemistry [41,
changes the properties of ( l a ) profoundly.
On adding a solution o f isopropylmagnesium chloride [at
least 2 equiv., relative t o ( I d ) ] in T H F to diphenylphenoxymethane ( I d ) at 65 O C , a colorless solution results. If HMPT
(30 equiv.) is now added, the mixture starts boiling and gradually assumes a deep red color. After 96 hours there is no
(Id)present in the hydrolysis product (gas chromatography:
10m SE-30 column, 5 % o n Chromosorb W, 24 ml N?/min,
250 "C), and after one crystallization the melting point is that
of triphenylmethanol (2d) (m.p. 161-161.4 "C). Using only
H M P T as solvent, the rearrangement is complete after 30 min
at 110 "C (see Experimental).
A 0.13 N solution of ( I d ) in ether was refluxed with an excess
of isopropylmagnesium chloride in presence of H M P T for
several hours, and then diluted with T H F in a closed apparatus, the ratio of dilution varying from 1 : 1000 t o 1 : 125.
The resulting solutions exhibited a well developed absorption
band, hmax = 461 nm, which obeyed the Beer-Lambert law.
The band differs from the absorption measured earlier "1 for
( I c ) only in a shift t o longer wavelengths by 1 2 n m . We
suggest that ( l a ) , Hal = CI, forms solvent-separated ion
pairs in presence o f HMPT. Our measurements on magnesium derivatives of diphenylmethane, triphenylmethane, and
fluorene led to similar results [51.
Thus we have demonstrated by chemical and spectroscopic
means, and using a simple model, that organomagnesium
compounds may assume pronounced carbanionoid[6]
properties.
Experimental:
HMPT (0.60mole) is added dropwise under argon t o an
ethereal solution (100 ml) of isopropylmagnesium chloride
(0.097 mole). The ether is then removed by distillation and
( I d ) (0.04 mole) is added at 110 O C to the pale yellow, viscous
solution. A clear red solution is formed with evolution of
gas (propane). After 30 min the mixture is cooled in an ice
bath and treated with twice its volume of 5 N HCI. The
colorless crystals of (2d) (yield 95 % after filtration, washing
with water, and drying) are recrystallized from ethanol
(yield 83%; m.p. 161-161.5 "C).
Received: December 17, 1969
[ Z 131 IE]
German version: Angew. Chem. 82. 136 (1970)
[*I Priv.-Doz. Dr. Hans F. Ebel, Dipl.-Chem. V. Dorr, and
Dr. B. 0. Wagner
Organisch-Chemisches Institut der Universitat
69 Heidelberg, Tiergartenstrasse (Germany)
I**]This work was supported by the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie, and the Wirtschaftsministerium/LandesgewerbeamtBaden-Wiirttemberg.
[I] G. Wirtig and E. Stahnecker, Liebigs Ann. Chem. 605, 69
(1957).
[2] H. F. Ebel and R . Schneider, Angew. Chem. 77, 914 (1965);
Angew. Chem. internat. Edit. 4 , 878 (1965).
[3] H . Normanr, Angew Chem. 79, 1029 (1967); Angew. Chem.
internat. Edit. 6, 1046 (1967).
141 S . J . Rhoads and R . W. Hoider, Tetrahedron 25, 5443 (1969).
[5] H . F. Ebel (lecturer), B. 0.Wagner, and V . Dorr, paper read
at the Chemiedozententagung, Karlsruhe 1969.
[ 6 ] H . F. Ebel, Fortschr. chem. Forsch. 12, 387 (1969).
Nucleophilic Imino- and Aminomethylation
of Ketonest11 [**I
Spectral properties and the tendency to rearrange depend o n
the nature (not specified in the formulas) of the bonds involving the metal atoms; only derivatives ( I ) , in which
the C-R bond is ionic, are deeply colored and capable of
rearrangement.
Angew. Chern. internat. Edit. / Vol. 9 (1970)
No. 2
By Thomas Kauffmann, Edgar Koppelmann, and Heike Berg [*I
Electrophilic aminomethylation (Mannich reaction) is a well
known important reaction step in organic synthesis. We have
now found that an aminomethyl group can be introduced
163
Документ
Категория
Без категории
Просмотров
0
Размер файла
144 Кб
Теги
rearrangements, diphenylphenoxymethylmagnesium, chloride, ionization
1/--страниц
Пожаловаться на содержимое документа