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Detection of Valence Tautomerism between 2H-1 3-Thiazete and N-Alkylidenethiocarboxamide.

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Table I . [)at21 for compounds ( I ) and ( 2 ) . The molecular ion is observed in the 70eV mass spectrum of all compounds
(2)
(1)
R
yield
"'41
(Oi
CbH,
Ih)
p-CH,Cda
P-CH 10CbHa
P-CICJ,
(c)
(0)
58
54
52
57
IR
b. p. ["C!torr]
m.p. [ T I
b. p. ["C,'torr]
m. p. ["C]
yield
"'/,,I
5210 I
19
40
53--54
68
76
88 12
78
65
72
112:12
118
14-76
[cm
I
~
'1
'F-NMR
[cl
1602, 1560 [d]
-4 9
1605, 1585, 1560 [a]
1600, 1580, 1560 [h]
1602, 1882, 1560 [b]
-48
-50
-5 1
La] Film. [b] in KBr: [c] 6 values [ppm] relative to CF,COOH a s external standard. in CHCI?, singlets.
kis(trifluoromethyl)-6H-1,3,5-oxathiazines
( [)I2),
which afford
2H-1,3-thiazetes (2) on thermolysis ( 140°C/12 torr) (Table
1).
Detection of Valence Tautomerism between 2H-1,3Thiazete and N-Alkylidenethiocarbxamide[**l
By Klaus Burger, Josef Albanbauer, and Walter Foag[*]
This ring contraction is the result of a retro-Diels-Alder
reaction[3' followed by an electrocyclic ring closure[41.
The constitution of compounds ( I ) and (2) is verified
by the spectroscopic data, the fragmentation pattern in the
mass spectrum, and by elemental analysis['!
The 2H-1,3-thiazetes (1)12] shown by their spectra['] to
exist-exclusively in cyclic form at room temperature are in
valence-tautomeric equilibrium with the open chain N (perfluoroisopropylidene)thiocarboxamides (2) at elevated
temperature. The presence of (2), and thus the occurrence
of thermally induced ring openingL3],is proved by trapping
reactions.
General procedure:
Two equivalents of hexafluoroacetone is passed onto a vigorously stirred solution of a thiocarboxamide (20g) in anhydrous
ether (250ml) at -20 to 0°C. The reaction mixture is then
treated simultaneously with an equimolar amount of POC13
and a fourfold amount of pyridine and left to stand for 48
to 72h at -30°C. After removal of precipitated salt, the
ethereal phase is washed with ice-water, dried over Na,SO,,
and concentrated. The residue is digested several times with
hexane and recrystallized from methanol after removal of
hexane.-Product ( I ) obtained in this way is decomposed
at 120-l4O0C/12 torr in the course of 20 to 80h. The crude
product (2) is purified by column chromatography [silica
gel; elution of any residual ( I ) with CCI,, and of (2) with
CHCI 3] and then fractionally distilled or recrystallized from
hexane.
13i
Table 1. Data for compounds ( 3 ) to (5). The molecular ion
in the 70 eV mass spectrum of all compounds.
Cpd.
[X]
M.p. ["C]
b.p. ["C:torr]
"F-NMR [a]
6 [ppm], J [ H r ]
73
81
- 6.8 (s)
78
56
-6.7 (s)
79
75
-
75
58
- 6.7
78
86
61 -68/0.1
96-98\02
6 1-63
81
86-88
-4.7 (s)
(s)
-6.9 (q. 11.0) [b]
-9.7 (4, 11.0)
-6.9(q. 11.0) [b]
-9.7 (4, 11.0)
(40)
(4b)
(50)
hewafluoroacctone. 684-16-2: C,H,C(=S)-NH,. 227-7%4.
p-CH,C,H,C(=S)-NH,. 2362-62-1 : p-CH,0C,H,C(=SI-NH2.
11-CIC,H,C(=S)-NH,.
2521-24-6
(Sb)
p-CIC,H,
(3b)
(3r)
131))
1362-64-3 :
D. M . Lenzul and L,. H. Dirrtlap jr.. J. Am. Chem. Sac. 94. 6562 (1972):
W Adum. J.-C. Liii, and 0. Roilrryurz. J. Ore. Chem. 38. 2269 (1973).
[2] 1,3,5-0xathiarin-6-ones, see: A . S r h u l x and J . Gouidrler.. Tetrahedron
Lett. 1073, 221.
[3] t l . M/i,//who.: Diels-Alder-Reaktion. Thieme, Stuttgart 1972. pp. 152ff.
[4] G. Muier ' Valenzisomerisierungen. Verlag Chemie, Weinheim 1972, pp.
[I]
89ff.
[ 5 ] J 4lho11houcv.Dissertation. Technische Universitat Munchen, scheduled
for 1975
observed
Yield
CAS Registry numbers
( l u J . 57014-91-2: ( l b ) . 57014-92-3: ( 1 0 . 57014-93-4: ( I d ) . 57014-94-5.
/ 7 0 ) , 57014-95-6: ( 2 h i . 57014-96-7; i c ) . 57014-97-8. ( 2 d ~ 57014-98-9:
.
i30i
IS
R1
R'
ChH,
r-C,H,>
CbH,
c-C,H i
p-CH,C,H,
f-C,H9
p-CH,C,H,
c-C,H, r
C,Hi
p-CH,C,H,
C&,
Received: Seplember 15, 1975 [Z 315a I€]
German version: Angew. Chem. X7, 816 (1975)
f41
81
6.7 (s)
(s)
- 4.9
[a] Relative to CF,COOH as external standard, in CHCI,.
[b] Shows additional fine structure.
[*I
Priv.-Doz.
Dr. K. Burger, Dip].-Chem. J. Albanbauer, and W. I'oag
Organisch-Chemisches Institut der Technischen Universitiit
8 Munchen 2, Arcisstrasse 21 (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie.
[**I
767
Smooth conversion of (1) into the S-irnino-1,3-thiazol-2ines ( 3 a ) to (3d) is accomplished in boiling xylene in the
presence of isocyanides141. Reaction of (1) with phosphorus
pentasulfide without solvent at 140°C gives good yields of
3H-1,2.4-dithiazoles (4a) and (4h) which are also accessible
from the N-(perfluoroisopropy1idene)carboxamides"' and
phosphorus pentasulfidelbI; finally the trapping reaction with
norbornene affords the annelated 5,6-dihydro-4H- 1,3-thiazines
( S a ) and (Sb).
if (1) is heated to 140°C without a trapping reagent it
turns yellowish brown but immediately regains its original
pale yellow color on cooling.-The reactions mentioned can
readily be described in terms of a thermally mobile equilibrium
( 1 )a 2 ) .
silyliminophosphorane (2)[".51. Thus, we have possible means
of access to the novel aminobis(imino)phosphoranes'5.'''
without having to resort to rcactions involving azides.
Bis(trimethylsilyl)aminomethyliminotrimethylsilyliminophosphorane ( 3 ) occurs only as intermediate product in the
reaction of (2) with ( I ), as can be observed by the appearance
and disappearance of the 31P-NMRsignal at -46.7 ppm during the course of thereaction. On addition of a second molecule
of (1) to the ylidic P=NCH3 bond a compound is finally
obtained which melts at 171"C, is readily soluble in most
organic solvents, and to which we assign the structure
of a 1,3-dimethyl-2-bis(trimethylsilyl)amino-2-trimethylsilylimino-4,4.4-triphenyI-1,3.2h5,4~~s-diazadiphosphetidine i 4 a /
on the basis of elemental analysis, molecular weight determination, and NMR spectra['!
S-Irnino-4,4-his(trijluoromethyl)-l,3-thiazol-2-ines
(3)
Equimolar amounts of (I)[*] and isocyanide are refluxed for
12 to 36 h in anhydrous xylene. The residue left on distillation
of the solvent crystallizes on rubbing; it is recrystallized from
hexane.-The procedure can be applied directly for the preparation of compounds ( 5 ) .
3,3-Bis(trijluo~omethyl)-3H-l,2,4-dithiazoles
(4)
Equimolar amounts of ( 1 ) and phosphorus pentasulfide
are stirred for 24 h at 140°C. Workup is by column chromatography on silica gel (elution with CCIJand subsequent fractional
distillation.
Received: September 15, 1975 [Z 315b IE]
German version: Angew. Chem. 87, 816 (1975)
CAS Registry numbers
i l i . R ' = C , H , . 57014-95-6: ( 1 ) R'=p-CH,C,H,,
57014-96-7:
i l l . R'=p-CIC6HI, 57014-98-9: ( 2 ) . R ' = C , H , . 57015-05-1 :
/ 2 ) . R1=p-CH,C,H,. 57015-06-2: / 2 ) . R1=p-CIC,H4. 57015-07-3:
r-C,H,NC. 7188-38-7. c-C,H, ,NC. 931-53-3: i 3 a ) . 57014-99-0:
13 h ) . 57015-00-6 ; 13<.1, 5701 5-01-7 : i 3 d ) . 57015-02-8 : i 4 r i i . 5501 5-72-0:
i 4 h ) . 55015-74-2: / 5 a ) , 57015-03-9: i 5 h ) . 57015-04-0
[ I ] The '"F-NMR spectra of / I / and 14) contain the signals of the
two magnetically equivalent CF, groups at 6 = -4.7 to -5.1 ppm.
uhereasfor ( 2 ) a chemical shift resembling that of N-(perfluoro~sopropy1idene)carboxamides ( 6 = - 9 to - IOppm) should be expected.
[2] K . Hur(ger, J . .4lhud~uirer.and M . Egg/ersdor{rr. Angew. Chem. 87. X I 6
(1975): Angew. Chem. internat. Edit. 14, 766 (1975).
[ 3 ] Electrocyclic reactions. see C . Muier. Valenzisomerisierungen. Verlag
Chemie. Weinheim 1972. pp. 89R., and references cited therein.
[4] N . P. G u m b a r w i i . E . M . Rokhlin, Yu. V Zrifmuii, L. A. Sirno~r~uri,
and
I . L. Kiiuiii~unriDokl. Akad. Nauk SSSR 166, 864 (1966); Chem. Abstr.
6 4 , 15861 (1966).
[ 5 ] W Sreglicli, K . Burger. M . Diirr, and E . Burgis, Chem. Her. 107. 1488
(1974).
[6] K . Burger, J. Alhanbuurr. and M.: Str1,i.h. Synthesis lY75, 57.
Diazadiphosphetidinesby Reaction of Arninoiminophosphanes with Irninophosphoranes"]
By Rolf Appel and Mechthild Halstenberg[*]
The use of iminophosphoranes as donors of imino groups
has previously only been known for those reactions, which-as
e. g. thereactions with carbonyl compounds"] or e p ~ x i d e s ~ ~ l lead to the corresponding oxophosphoranes via O/NR
exchange. We have now found that direct transference of
the methylimino group and liberation of the tertiary phosphane takes place when triphenyl(methy1imino)phosphorane
(1) is allowed to react with bis(trimethylsilyl)aminotrirnethyl-
[*I
Prof. Dr. R. Appel and Dipl.-Chem. M Halstenberg
Anorganisch-chemisches Institut der Universitht
53 Bonn, Max-Planck-Strasse 1 (Germany)
768
Evidence for this reaction is also afforded by the fact that
compound ( S ) , obtainable from ( 2 ) and trimethylsilyl azide,
reacts smoothly with ( 1 ) to give (4b)"'.
Experimental
A neat mixture of ( 1 ) (1.46g, 5mmol) and (2) (0.70g,
2.5mmol) is heated for 2 h at 140°C. The triphenylphosphane
that is formed is removed by sublimation (ca. 5 h at
100"C/0.4 torr;0.53 g, 81 %). The residue is recrystallized twice
from acetonitrile (2 x 5 ml); 0.8 1 g (54 %) of analytically pure
(4u) is obtained. In theanalogous reaction indichloromethane
a transitory sharp signal is observed at -46.7ppm in the
3'P-NMR spectrum.
A solution of ( 1 ) (0.58g, 2mmol) and ( 5 ) (0.73g, 2mmol)
in dichloromethane (2 ml) is stirred for 24 h at room temperature. On addition of acetonitrile a precipitate is formed, which
after filtration and multiple recrystallization from dichloromethane/acetonitrile affords pure (4h) r0.17 g, 15 yield,
m.p: 116"C].
Receibed: August 1 I . 1975 [Z 306a IE]
German version: Angew. Chem 87. 810 (1975)
Part 65: R. A p p d and
M . Hulsrenherg, Chem. Ber.. in press.
[2] H . Stuurlinyer and E. Haurrr, Heh. Chi,. Acta 4, 861 (1921): R. A p p d
and A . Hauss. Chem. Ber. 93. 405 (1960).
[3] R. A p p e l and M. H u l a r ~ ~ ~ i h eChem.
ry.
Ber.. in press.
ke and M: Flick, Angeh. Chem. 85, 586 (1973): Angew. Chem.
internat. Edit. 12. 585 (1973).
[5] 0. .J. Schrrrr and N . Kiili~i.Chem. Ber. 107. 2123 (1974).
161 E. h'iecku and W Flick. Angeu. Chem. 86. 128 (1974); Angew. Chem.
internat. Edit. 13. 134 (1974).
[7] ( 4 ~ ) '"P-NMR (in CHCI,): A H type: 6=-6.0 (d). -4.9 (d) ppm:
*Jpp = 3 2 H r . 'H-NMR (in CDCI,). 6 =
-0.05 (s) silylamino-H. + O O X
(s) silylamino-H. - 2 2 0 (d) CH,, -7.18 to -7.97 ( m ) ppm C,H,;
iJp,,.,=13.5 Hr.
/ 4 h ) : "P-NMR (in CHCI,): AB type: 6 = -0.6 Id). + 3 3 ( d ) p p m .
z.I,p =34 H r . 'H-NMR (in CDCi2):S = 0 6 to -0.25 (m) silyl-H. - 2 44(d)
CH,. -7.35 to -8 18 (m) ppm C,H,: 'J,,,.=15
Hr
[I] Part 66 of Nonmetallic lmine Compounds.
~
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valence, alkylidenethiocarboxamide, tautomeric, detection, thiazete
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