close

Вход

Забыли?

вход по аккаунту

?

Formation of Tetramethyl Furantetracarboxylate form Dimethyl Acetylenedicarboxylate.

код для вставкиСкачать
The structure of product (8) follows from its cleavage by acid
to cyclohexanone (2,4-dinitrophenylhydrazone,m.p. 162 "C)
and 4-phenylsemicarbazide (benzylidene derivative, m. p. and
mixed n1.p. 180°C).
Received: March 2lbt. 1966
1Z 178/14 IE]
(icrnian version: Angew. Chem. 78, 587 (1966)
[I] E. Schnrirz, R. Ohme, and G. Kozakiewicr, Z . anorg. allg.
Chem. 339, 44 ( I 965).
121 E. Sclrrnitz, R . Ohtne, and S. Schramm, Tetrahedron Letters
1965, 1857.
[3] E. Sclrnritz and D. Habisch, Rev. Chim. (Bucarest) 7, 1281
( 1962).
[4] R . Gus/, Angcw. Chcm. 74, 470 (1962); Angew. Chem.
intcmat. Edit. I , 268 (1962).
The trapping reaction leading to the carbene (3) has parallels
i n the investigations of diazo derivatives by R.Hirisgen et al. [*I
The or-keto ester (5) can then pass into the triester (1) by
decarbonylation. The following findings support this assumption: exclusion of oxygen reduces the yield of ester ( 1 ) to
0.01 %; the carbon monoxide liberated can be identified; the
radical (4) can be trapped by other acetylenic compounds;
and the carbene (3) can be trapped by sulfur. The correct
order of the two steps is still open t o question. The stability
of tetramethyl furantetracarboxylate under the reaction
conditions has been ascertained.
Received: March 21st, 1966
[ Z 181/17 I E I
German version: Angew. Chern. 78, 588 (1966)
[I] C. F. Huebtrer, E. Donogliue, L. Dorfinan, F. A . Stuher,
N . Danieli, and E. Wenlcert, Tetrahedron Letters 1966, 1185.
[2] R. Hnisgen et nl., Chem. Ber. 97, 2864 et seq. (1964).
Formation of Tetramethyl Furantetracarboxylate
from Dimethyl Acetylenedicarboxylate
A Simple Method for Selective Acylation of
Cytidine on the 4-Amino Group
By Priv.-Doz. Dr. E. Winterfeldt and cand. chem. G. Giesler
Organisch-Chemisches Institut
der Technischen Universitit Berlin (Germany)
By Dr. K. A. Watanabe and Prof. Dr. J . J. Fox
In addition reactions of dimethyl acetylenedicarboxylate we
isolated varying yields of the triester ( I ) . We have now found
that this ester is also formed when dimethyl acetylenedicarboxylate is heated alone at 180"C, and that the yield is
increased to 25 if the sealed tube is filled with oxygen and
the reaction catalysed with copper powder. Support is thus
withdrawn from the rather complicated mechanism proposed
by Huebrier et 01.
when he isolated (1) in diene syntheses
with acetylenedicarboxylic esters.
The structure of ( I ) was supported by, inter alia, formation
of (2) on hydrolysis and by the spectral data.
Division of Biological Chemistry, Sloan-Kettering Institute
for Cancer Research, Sloan-Kettering Division of Cornell
University Medical College, New York, N.Y. (U.S.A.)
T o our knowledge, the only reported procedure[Zl for the
preparation of N(4)-acetylcytidine ( l a ) is the reaction of
cytidine with I-acetoxy-2(1H)-quinolones (65 % yield).
NHR
(b): R = CO-CeH,,
(C): R = CO-(CH,)2-CH,
O H OH
121 "C
1750, 1620, 1590, 1160, 1110, 1070 cm-1
273mp (E= 1 5 4 0 0 ) , s h o u l d e r a t 2 4 8 m p ( ~ =10900)
in ether
NMR: 5.72r (3 H), 6.02 (3 H), 6.12 (3 H),
6.17 (3 H).
( I ) : M.p.
IR:
UV:
(2): M.p.
IR:
71 "C
1850, 1830, 1740, 1640 cm-1
232 m p (E = 9850)
UV:
N M R : 6.22.: (3 H ) ; 6.60 (2 H), J = 2.5;
2.43 ( I H), J = 2.5
The formation of ( I ) can be understood if it is assumed that
acetylenedicarboxylic ester reacts in the 1,3-dipolar form ( 4 ) .
C H302C- C =C -C 0 2 CH3
CI
A simple and direct synthesis, giving a n almost quantitative
yield of the selectively blocked nucleosides ( I ) , consists in
treatment of cytidine with aliphatic or aromatic acid anhydrides in boiling methanol.
The structures of products were secured as follows: All gave
ultraviolet spectra (details for p H 6.4 in the table) similar to
those of poly-0-acetylated N(4)-acetylcytidine [31 and N(4)acetyl-1 -methylcytosine"+I. Elemental analyses agree with
monoacetylated products. The compounds have sharp
melting points and give only one spot on thin-layer chromatography in two solvent systems [Sl. Their infrared spectra
(KBr pellets) show no absorption bands in the region 1650
to 1800 cm-1 that could be attributed to an ester-carbonyl
group.
C H 3 0 2 C q- C - C OzC H3
Emin
!
(3)
lo,
268 [bl (4400)
(6100)
225
212
(18200)
(/cJ
182-183
295
245
210
(8500)
(17000)
(19300)
//b)
238-239
302
257
(9900)
(ISOOO)
(41
-278
225
(7500)
(7600)
--
5)
284
228
(7900)
(8300)
[a] Determined o n a Thomas-Hoover melting-point apparatus; corrected.
[b] Mizrrno [2] gives for neutral aqueous solution: Amax
;,,in
= 270, 221 niw.
Angew. Clzem. internut. Edit.
Vol. 5 (1966) 1 No. 6
-=
296, 241 rnp;
579
Документ
Категория
Без категории
Просмотров
2
Размер файла
106 Кб
Теги
forma, formation, furantetracarboxylate, dimethyl, acetylenedicarboxylic, tetramethyl
1/--страниц
Пожаловаться на содержимое документа