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New Synthesis of 1 2 5-Thiadiazole and Some of its Derivatives.

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the product does not have the structure (4), for the hydrolysis
gives 1-pentene and not cis-2-pentene. This appears to
indicate structure (5), but hydrolysis with D20 gives a monodeuterio-I-pentene in which a saturated C atom has been
deuterated, as is shown by the position of the C-D stretching
vibration (? = 2140 cm-1) on comparison with the spectra of
alkenes deuterated at known positions 131.
phenyl-1,2,5-thiadiazole(m.p. and mixed m.p. 43-44 " C ) ;
and 0.0163 mole of c+phenylphenethylamine and 0.0165
mole of S4N4 give a 60 % yield of 3,4-diphenyl-1,2,5-thiadiazole (m.p. and mixed m.p. 85-86 "C)
If an excess of diazomethane is used with compound (3),
insertion of a second CH2 group per alane molecule occurs,
so that subsequent hydrolysis gives propane and, above all,
3-methyl-l-pentene, but no hexene, as well as ethane and
1-pentene. Thus an isomerization ( 4 ) + (5) is excluded.
[ I ] L. M. Weinstock, Ph.D. Thesis, University of Indiana, 1958 ;
Univ. Microfilms (Ann Arbor, Mich.) Mic 58-2974.
[2] Ital. Patent Appln. 2204/66 (Feb. lst, 1966).
[3] Although the possibility of obtaining benzo-1,2,5-thiadiazole
by reaction of o-phenylenediamine with S4N4 has been briefly
mentioned in the literature [l], the reaction of S4N4 with vicinal
diamines containing amino groups bound to aliphatic carbon
has not been described.
[4] G. M. Gill, Ph.D. Thesis, University of Indiana (1963);
Univ. Microfilms (Ann Arbor, Mich.) 64-468.
[5] Y. Berrini and P.Pino, Angew. Chem. 77,262 (1965); Angew.
Chem. internat. Edit. 4, 239 (1965).
[6] Ital. Patent Appln. 2203/66 (Feb. Ist, 1966).
The formation of 3-methyl-1-pentene on alcoholysis after
reaction of compound (3) with an excess of diazomethane
throws light on the nature of the rearrangement. The 3-methyl
group results from the second CH2 insertion, so after the
first insertion a n allyl rearrangement onto aluminum
according to (4) + (6) must have occurred.
Received: February 23rd, 1966 [Z 169/1000 IE]
German version: Angew. Chem. 78, 493 (1966)
Preparation of N-Stannylketenimines and Ketene
Ethyl Stannyl Acetals by 1,4-Hydrostannation
of Conjugated Systems
A recent paper o n allyl rearrangements on addition of dialkylalanes to substituted 1,3-dienes [41 supports our formulations.
By Prof. Dr. W. P. Neumann, Dr. R. Sommer, and
cand. chem. E. Muller
Received: February 16th, 1966
[Z 172/4 IE]
German version: Angew. Chem. 78, 492 (1966)
Institut fur Organische Chemie
der Universitat GieRen (Germany)
[ l ] H. Hoberg, Liebigs Ann. Chem., in press.
[2] G. W i k e and H. Miiller, Liebigs Ann. Chem. 629, 222 (1960);
G. Wilke and W . Schneider, Bull. SOC.chim. France 1963, 1462.
[3] E. G. Hoffmann, Liebigs Ann. Chem. 618, 276 (1958); H. W.
Schrotter and E. G. Hoffmann, ibid. 672, 44 (1964).
[4] J. J. Eisch and G. R . Husk, J. organomet. Chem. 4,415 (1965).
In the presence of catalysts at 60-80 "C conjugated dienes,
e . g . 1,3-butadiene, add organotin hydrides preponderatingly
at the 1,4-positions in a radical reaction 111. We now report a
polar 1,4-hydrostannation of conjugated unsaturated systems
whose C = C group is sufficiently polarized, e.g. of alkylidenemalononitriles ( I ) . N-Stannylketenimines (2) are thus formed, usually even at 20 "C and without a catalyst, in a strongly
exothermic reaction. This is surprising because previous
attempts to bring about reaction between organotin hydrides
and CN groups failed [21 and cinnamonitrile and acrylnitrile
react exclusively at their C = C groups [31.
____.
New Synthesis of 1,2,5-Thiadiazole and
Some of its Derivatives
By Dr. V. Bertini and Prof. Dr. P. Pino
CN
+
R'HC=C:
Istituto di Chimica Organica, Facolta di Scienze,
Universita di Pisa (Italy)
(1)
R,SnH + R' H C- C=C=N - S n R,
CN
I
I
H CN
(a)
(2)
Hitherto the only synthesis of 1.2,5-thiadiazole has been a
five-stage one affording poor yields
I n continuation of our study of the use of S4N4 for synthesis
of thiadiazole derivatives we have prepared 1,2,5-thiadiazole
=
(b.p. 94"C, n g = 1.5151, ultraviolet spectrum: A,,
254 mp, log E = 3.94) in 70 % yield by heating 0.0434 mole of
ethylenediamine with 0.0109 mole of S4N4 in 45 ml of a
mixture of 0-,nz-, and p-xylene for 2-3 hrI273J. The 1,2,5thiadiazole was isolated and purified by distillation of the
reaction mixture, followed by precipitation as Cd salt, decomposition of the latter in steam, and salting out of the
aqueous solution with NazS04. Under similar conditions
0.0326 mole of propylenediamine and 0.0109 mole of S4N4
yielded 3-methyl-l,2,5-thiadiazole[41(b.p. 121 "C; n g =
1.5053; Amax = 259 my, log E = 3.94) in 97 % yield.
Synthesis of mono- and di-aryl derivatives of 1,2,5-thiadiazole, which can be obtained in low yield by reaction of
S4N4 with alkylaromatic hydrocarbons of the type
R-CH2-CH2-R'
(with R = C6H5, C10H7; R' = H,
C6H5)[51, is accomplished in much higher yield and more
conveniently from the more readily accessible monoamines [6J
C ~ H ~ - C H Z - C H ( N H ~ ) - R ' (R' = H or C6H5). In this
way, boiling 0.0325 mole of phenethylamine with 0.0163
mole of S4N4 in the xylene mixture gives a 20 % yield of 3-
514
Compounds R'zC=C(CN)2 ( R = e.g. CH3, C6H5) react
analogously to ( I ) .
The N-stannylketenimines (2) are very reactive [4J. Their
structure follows, inter uliu, from the N M R spectra and the
very intense ketene imine bands at 2060-2110 cm-1 in their
infrared spectra (C-N absorption at 2180 cm-1 is also
present). They are readily soluble in hydrocarbons and
ethers, sensitive to moisture, and stable only up to about
5OoC. The average molecular weight of these viscous, undistillable liquids in benzene increases rapidly with concentration, which indicates association by means of pentacoordinated tin.
Reaction is slower the less polarized is the C=C group.
Electron-donating substituents R' decrease the reaction
velocity, as does replacement of CN by the more weakly
electron-attracting ester group: alkylidenecyanoacetates (3u)
and alkylidenemalonic esters (3b) also react with organotin
hydrides by 1,4-addition, giving ketene ethyl stannyl acetals
( 4 ) , but sometimes so slowly that 1,2-hydrostannation of the
C=C bond also occurs.
Angew. Chem. internut. Edit.
1 VoI. 5 (1966)
{ No. 5
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