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Formation of Phenylcarbenes by Photolysis of Phenyloxiranes.

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Formation of a 2-Thiocyanatopyrimidine from a
l-Amino-2-thioxo-l,2-dihydropyrimidine
and
Dimethylformamide/POCl3
Formation of Phenylcarbenes by Photolysis of
Phenyloxiranes
By Dr. H. Kristinsson and Prof. Dr. G. W. Griffin [I]
By Prof. Dr. E. C. Taylor and Dr. R. W. Morrison, Jr.
Department of Chemistry, Tulane University,
New Orleans, La.( U.S.A.)
Department of Chemistry, Princeton University,
Princeton, N.J. (U.S.A.)
We have found that photolysis 121 of trans-stilbene oxide
Condensation of malonodinitrile with thiosemicarbazide in
2 M ethanolic sodium ethoxide gives 1,4,6-triamino-2-thioxo1,2-dihydropyrimidine ( I ) , m.p. 261 "C (decomp.), in 34 %
yield. Treatment of ( I ) for 2 h at room temperature with the
dimethylformamide/POCl3 complex [I ] leads to 4,6-bis(dimethylaminomethyleneamino)-2-thiocyanatopyrimidine (2)
in 65 % yield. This compound melts at 130-131.5 "C and is
isolated by addition of the reaction mixture to crushed ice,
adjustment of the p H to 10 with 6 N sodium hydroxide, rapid
filtration, and recrystallization of the dried precipitate from
acetone/hexane.
The structure of (2) was indicated by its elemental composition, by a strong infrared absorption band at 2172cm-1
characteristic of the -SCN grouping, and by its chemical
reactions. For example, (2) was converted by either benzylamine at 95 OC or 1 N sodium hydroxide at room temperature
or refluxing 2 M ethanolic ammonia into 4,6-diamino-2mercaptopyrimidine [2]. Hydrolysis of (2) with cold 0.5 N
hydrochloric acid gave 4-amino-6-dirnethylaminomethyleneamino-24hiocyanatopyrimidine(3), m.p. 198.5-199 'C,
whereas hydrolysis with 6 N hydrochloric acid at 100 "C gave
barbituric acid. Hydrolysis with 4 N acetic acid at room
temperature afforded 4,6-bisformylamino-2-thiocyanatopyrimidine (4), m.p. 249°C (decomp.). Treatment of 1.0 g
of (2) with 4 g of chlorine in 15 ml of acetic acid gave rise
to 4,6-diamino-2,5-dichloropyrimidinein 71 % yield 131.
( l a ) [3] in 2-methylbut-2-ene leads to a 1 : 1 mixture of cis(Sa) and trans-2,2,3-trimethyI-l-phenylcyclopropane
(Sb) in
90 % yield [4]. In addition, the oxetane derivative (6) [5],
which is formed by addition of benzaldehyde to the solvent,
was isolated.
The cyclopropane derivatives (Sa) and (Sb) were also
obtained on photolysis [2] of triphenyloxirane (Ib) [3] in
either 2-methylbut-2-ene/benzene or 2-methylbut-2-ene alone.
However, here the main products were tetraphenylethane and
the oxetane (6).
These reactions apparently all involve the diradical(2), which
decomposes preferentially by Route A to the carbene (3)
plus the carbonyl compound ( 4 ) .
R,
c:
R,"
c=o
R3'
R
'
R,c=o+ R,"c:
R3'
R
1
'
H3C CH3
A
II5Cs
(sa)
+
+
H3C CH3
CH3
H
HsCs
H&CH3 H (56)
(a),
(b),
R
R
(c),
R = R' =
R' = R2 = H
R2 = CsH5; R3 = H
R2 = R3 = C6H5
= R3 = C&;
=
R'
=
H3T-F
H3C
H
(6)
R'
(2), R' = R 2 = -N=CH-N(CH3)2
(3), R' = -N=CH-N(CH3)2
R 2 = -NH2
(4), R' = R2 = -NH-CHO
We consider that the reaction of ( I ) with the dimethylformamide/POC13 complex involves initial formation of the 1,4,6tris(dimethylaminomethyleneamino) compound 141. The
(CH&N-CH=N-group o n N-1 could then cyclize with the
thioxo sulfur on C-2 to form a thiadiazole ring; loss of dimethylamine followed by cleavage of the N-N bond could
then yield (2).
Received: June 24th, 1965
IZ 13/847 IEI
German version: Angew. Chem. 77, 859 (1965)
[I] Z. Arnold and A. Holy, Collect. Czechoslov. chem. Commun.
27, 2886 (1962).
[2] W. Traube, Liebigs Ann. Chem. 331, 64 (1964).
[3] E. C . Taylor and P . Drenchko, J. Amer. chem. SOC.74, 1101
(1952).
[4] Reaction of 4,5-diamino-6-fluoropyrimidine
with dimethylformamide/POCl3 gives rise to 4,5-bis(dimethylaminomethyIeneamino)-6-fluoropyrimidine: A. G. Beaman and R. K . Robins, J.
med. pharrnac. Chem. 5, 1067 (1962).
Photolysis of tetraphenyloxirane (Ic) [3] in methanol/benzene gives benzhydrol methyl ether in almost 100 % yield.
Kirrnse and Horner [6] have previously used alcohols to trap
aryl carbenes.
All products were separated by gas chromatography and
identified by comparison with authentic samples 171.
Received: July Znd, 1965
[Z 40/865 IEI
German version: Angew. Chem. 77, 859 (1965)
[I] We gratefully acknowledge financial support from the Army
Research Office (Durham) N.C. (U.S.A.).
[2] The solutions were carefully degassed and irradiated for 10 h
at 40°C. The radiation source was an air-cooled Rayonet
Chamber Reactor (from the Southern New England Ultraviolet
Co., Middletown, Conn. (U.S.A.) containing sixteen 8-watt lowpressure mercury lamps.
[3] A . C. Cope, P . A.TrumbuII, and E. R.Trumbid1, J. Amer.
chem. SOC.80, 2844 (1958).
[4] G. L. Closs and R . A. Moss, J. Amer. chem. SOC.86, 4042
(1964).
[S] G. Biichi, C . G. Inman, and E. S . Lipinsky, J. Amer. chem.
SOC.76, 4327 (1954).
161 W . Kirmse, L. Horner, and H. Hofmann, Liebigs Ann. Chem.
614, 19 (1958); W . Kirmse, ibid. 666, 9 (1963).
[7] We thank Prof. G. Closs, University of Chicago (U.S.A.) for
copies of the infrared spectra of (Ja) and (56).
Angew. Chem. internat. Edit.1 Vol. 4 (1965) 1 No. 10
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phenylcarbenes, photolysis, formation, phenyloxiranes
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