close

Вход

Забыли?

вход по аккаунту

?

Bis(diethoxyphosphinyl)(trimethylammonio)-methylide a Stable N-Ylide.

код для вставкиСкачать
All products were separated by gas and elution chromatography and identified by comparison with authentic samples "1.
Received: February 9, 1968
[Z 754 IE]
German version: Angew. Chem. 80, 442 (1968)
[*I Dr. R. M. G. Nair and Prof. Dr. G . W. Griffin
Department of Chemistry, Louisiana State University
Lakefront, New Orleans, La., 70122 (U.S.A.)
[**I Dr. E. Meyer
Cassella A.-G.
6 Frankfurt/Main (Germany)
[l] We gratefully acknowledge financial support from the Petroleum Research Fund of the American Chemical Society.
121 The solutions were carefully degassed and irradiated in a
sealed quartz vessel at 40-70°C. The radiation source was an
air-cooled Rayonet RPR-100 Chamber Reactor (from The
Southern New England Ultraviolet Co., Middletown, Conn.
U.S.A.) containing sixteen 8-watt low-pressure mercury lamps, or
the larger preparative RPR-208 model. The yields reported are
based on reactions performed in the latter unit.
131 This compound (m.p. 281 "C) was obtained in 81 '% yield
by addition of diazofluorene to 3,4,5,6-tetrachloro-o-henzoquinone in ether under a nitrogen atmosphere. The solution was
then heated under reflux until nitrogen evolution ceased whereupon the solvent was removed and the residue recrystallized from
ethanol/acetonitrile.
[4] [a] W. von E. Doering and M. Jones jr., Tetrahedron Letters
1963,791; p] M . Jonesjr. and K. R. Rettig, J. Amer. chem. Soc.
87, 4013 (1965).
[51 H. Dietrich, G. W . Griffin, and R. C . Petterson, Tetrahedron
Letters 1968, 153.
161 W. Kirmse, L. Horner, and H . Hoffmann, Liebigs Ann. Chem.
614, 19 (1958); W. Kirmse, ibid. 666, 9 (1963).
171 We thank Dr. M. Jones jr., Princeton University, for copies
of the infrared spectra of (2a) and (Zb).
Bis(diethoxyphosphinyl)(trimethylammonio)methylide, a Stable N-YLide
By H. Gross and B. Costisella [*I
[Bis(diethoxyphosphinyl)methyl]dimethylamine ( I ) [I], which
is readily accessible from formamide dimethyl acetal and diethyl phosphite is smoothly converted by reaction with dimethyl sulfate or methyl iodide in dioxane at room temperature into the quarternary salts (2a) and (Zb), respectively, which are obtained pure when washed several times
appeared as a triplet a t T = 6.80 or 4.12, respectively, for
(Z) [ * I and (2) is not present in the spectrum of (2c). The
31P-NMR spectrarzl of the compounds (1)-(3) and of ( 4 )
[Na salt of (Z)]131 contain the following signals: ( I ) -18
ppm, (2) -11 ppm, (3) -28 ppm, (4)-33 ppm; the appreciably more negative shift of (3) compared with that of (2)
indicates delocalization of the free electron pair of the
carbanion as shown in (3b); this presumably accounts for
the stability of the ylide [41. The same delocalization is shown
on comparison of the chemical shifts of ( I ) and ( 4 ) .
The ylide (3) is readily soluble in water from which it can
be recovered unchanged by evaporation or extraction.
Addition of perchloric acid to a solution of ( 3 ) in dioxane
followed by addition of ether leads to regeneration of the
perchlorate (2c).
Received: March 15, 1968
[Z 759 IE]
German version: Angew. Chem. 80, 445 (1968)
[*I Doz. Dr. H. Gross and Dip1.-Chem. B. Costisella
Institut fur Organische Chemie der Deutschen Akademie
der Wissenschaften zu Berlin
DDR-1199 Berlin-Adlershof, Rudower Chaussee (Germany)
[l] H . Gross and B. Costisella, Angew. Chem. 80, 364 (1968);
Angew. Chem. internat. Edit. 7, 391 (1968).
[2] We thank Dr. E. Grundemann, Dr. W. Wiecker, and Dipl.Chem. A . R. Grimmer for measurement of the 1H- and 31P-NMR
spectra.
[31 Compound (4) is obtained from ( I ) and NaH in dioxane.
[4] An analogous effect was assumed to explain the stability of
the dicyano(trimethy1ammonio)methylide described by 2. Arnold, Chem. and Ind. 1960, 1470; Coll. Czech. chem. Commun.
26, 1113 (1961).
Synthesis of Both Hexobarbital Enantiomers and
of (+)-Thiohexobarbitalfrom( +)-Methyl 2-Cyano-2(1-cyclohexeny1)propionate I11
By J. Knabe and D . Strauss[*l
(2)
(a), Xo = CH30S03@
(b), XQ = 1 0
(c),
x@ =
ClO,@
with ether [ ( 2 a ) : yield 76 %, m.p. 105-106 OC; ( 2 b ) : yield
85 %, m.p. 116-118 O C , N M R spectrum TCH~-CH*- = 8.58
triplet (J = 7 Hz), 5.65 multiplet (J = 8 Hz, T - N ( c H ~ ) ~= 6.10
singlet, T>CH- = 4.12 triplet (J = 20 Hz)]. When treated
with silver perchlorate in a n aqueous medium, (2a) gave the
perchlorate (2c), m.p. 134-135 O C , in 90 % yield.
The phosphonate proton of ( 2 ) , like that of ( I ) [11, is very
strongly acidic. If (2al is stirred for ca. 30 min with saturated
aqueous potassium carbonate solution and then shaken with
benzene, subsequent separation of the organic phase leads,
after drying and evaporation in a vacuum, to a colorless
crystalline compound of m.p. 38-40 "C, which according to
its ekmental analysis and spectral properties has the structure
of a n N-ylide ( 3 ) , namely, bis(diethoxyphosphinyl)(trimethylammonio)methylide. lH-NMR spectrum: T C H ~ - C H ~ - =
8.74 triplet ( J = 7 Hz), 6.07 multiplet ( J = 4 Hz), T - N ( c H ~ ) ~=
6.47 singlet. The signal of the phosphonate proton that
Angew. Chem. internat. Edit.
1 Yol. 7 (1968) / No. 6
Since the enantiomers of hexobarbital[z] have different
pharmacological properties [31 and resolution of the racemate is difficult o n a large scale [21, we sought an alternative
route for their synthesis.
We have found that the two hexobarbital enantiomers can be
prepared in good yields from (+)-methyl 2-cyano-2-(l-cyclohexeny1)propionate [ ( + ) - ( 2 ) ] : (-)-hexobarbital [(-)-(4)]is
obtained via (-)-iminohexobarbital [(-)-(3)] by condensing
(+)-(2) with N-methylurea and (+)-hexobarbital [ ( + ) - ( 4 ) ]
is obtained by condensing ( + ) - ( 2 ) with dicyanodiamide;
in the last-mentioned reaction (-)-cyanodiiminobarbital
[(-)-(5)], which is first formed, gives [ ( + ) - / 4 ) ]o n methylation with dimethy1 sulfate and subsequent hydrolysis.
The formation of optically active hexobarbital from (+)-(2)
and N-methylurea in about the same optical purity as is obtained by resolution of the racemate (21 confirms previous
findings [41 that condensation of disubstituted cyanoacetic
esters with N-methylurea is stereoselective [51. We have found
this also to be the case with N-methylthiourea, since we obtained (+)-thiohexobarbital from (-)-2-cyano-2-(l-cyclohexeny1)propionic acid [(-)-(I)] and N-methylthiourea.
The (+)-form of ( 2 ) is easily obtained from racemic ( I ) by
resolution and subsequent esterification [61.
463
Документ
Категория
Без категории
Просмотров
0
Размер файла
140 Кб
Теги
trimethylammonio, diethoxyphosphinyl, methylidene, bis, ylide, stable
1/--страниц
Пожаловаться на содержимое документа