DIPHENYLMETHYL PROTECTIVE GROUP IN THE SYNTHESIS
403
b. Compound VIII was prepared in a similar way
from triazole XX, except that the reaction time was
7 h.
3-Nitro-5-phenoxy-1H-1,2,4-triazole (XIII). To a
suspension of 1.2 g of compound VI in 10 ml of
benzene, 5 ml of 96% sulfuric acid was added. The
mixture was stirred for 8 h at 20 C, the benzene layer
being changed twice during this time. After the reac-
tion had been complete, the organic and acidic layers
were separated. The acidic layer was carefully neutra-
lized with 25% aqueous ammonia under cooling.
Compound XIII precipitated and was purified by re-
crystallization from 2-propanol or water. An addi-
tional portion of XIII can be extracted from the
mother liquor with ethyl acetate.
1-Diphenylmethyl-5-(imidazol-1-yl)-3-nitro-1H-
1,2,4-triazole (IX). a. Compound II, 5.0 g, and 3.2 g
of imidazole in 25 ml of DMF were heated at 80
90 C with stirring for 36 h. Isolation and purification
of compound IX were performed as described for
compound V.
b. Compound IX was prepared in a similar way
from triazole XX, except that the reaction time was
24 h.
5-Diethylamino-3-nitro-1H-1,2,4-triazole (XIV)
was prepared from 2.0 g of compound VII, 10 ml of
96% sulfuric acid, and 40 ml of benzene as described
for compound XII, except that to isolate the product
the acidic layer was simply diluted with two volumes
of water. Compound XIV precipitated after 12 h and
was recrystallized from 2-propanol.
5-(5-Amino-1H-1,2,4-triazol-1-yl)-1-diphenyl-
methyl-3-nitro-1H-1,2,4-triazole (X). a. Compound
II, 5.0 g, 5-amino-1H-1,2,4-triazole, 1.5 g, and 1.9 g
of K2CO3 DMF (20 ml) were used as reagents. The
reaction conditions and product isolation procedure
were analogous to those described for compound IV,
except that the reaction time was 16 h. The product
was recrystallized from either DMF or 2-propanol.
3-Nitro-5-piperidino-1H-1,2,4-triazole (XV) was
prepared from 1.3 g of compound VIII, 5 ml of 96%
sulfuric acid, and 10 ml of benzene as described for
compound XII. After the benzene layer was separated,
the acidic layer was neutralized with aqueous potas-
sium hydroxide, and the product was extracted with
ethyl acetate (4 50 ml). The combined extracts were
dried over MgSO4, and the solvent was evaporated.
Compound XV was purified by recrystallization from
a mixture of 2-propanol and water (1:2).
b. Compound X was prepared in a similar way
from triazole XX, except that the reaction time was
10 h.
5-Dodecylsulfanyl-3-nitro-1H-1,2,4-triazole
(XI). a. A solution of 0.53 g of compound V and
0.20 g of phenol in 10 ml of trifluoroacetic acid was
heated at 65 70 C, following the reaction progress by
TLC. After 5 h, the solution was poured into water,
the precipitate was filtered off and dried in a vacuum
at 40 C for 10 h. Compound XI was recrystallized
twice from n-heptane.
5-(Imidazol-1-yl)-3-nitro-1H-1,2,4-triazole (XVI)
was prepared from 1.2 g of compound IX, 5 ml of
96% sulfuric acid, and 10 ml of benzene as described
for compound XII and isolated as described for com-
pound XV.
b. A mixture of 5.1 g of compound IV, 50 ml of
96% sulfuric acid, and 20 ml of benzene was stirred
at 90 C for 2h. After the reaction had been complete,
the benzene layer was decanted, and the residue was
poured into water. A black solution formed. After 6 h,
compound XI precipitated from the aqueous solution
and was filtered off, dried in air, and recrystallized
twice from n-heptane.
5-(5-Amino-1H-1,2,4-triazol-1-yl)-3-nitro-1H-
1,2,4-triazole (XVII). A mixture of 0.75 g of triazole
X, 15 ml of 96% sulfuric acid, and 10 ml of benzene
was stirred at 90 C for 2 h. After the reaction had
been complete, the benzene layer was decanted, and
the residue was poured into 30 ml of water and neutra-
lized with 25% aqueous ammonia. The aqueous solu-
tion was additionally extracted with ethyl acetate
(2 20 ml). After 8 h, compound XVII precipitated
from the aqueous solution. It was filtered off, dried in
air and recrystallized from a mixture of 2-propanol
and water (1:2).
3-Nitro-5-phenylsulfanyl-1H-1,2,4-triazole (XII).
A mixture of 1.15 g of compound V, 10 ml of 96%
sulfuric acid, and 40 ml of benzene was vigorously
stirred for 8 h at 20 C. During this time, the benzene
layer containing benzhydrol was twice decanted into a
Petri dish and a new portion of benzene was added to
the reaction mixture. After the reaction had been
complete, the benzene and sulfuric acid layers were
separated. The acidic layer was poured into 50 ml of
water under cooling. Compound XII precipitated and
was filtered off, dried in air, and recrystallized from
2-propanol.
1-Diphenylmethyl-5-methylsulfanyl-3-nitro-1H-
1,2,4-triazole (XIX) was prepared from 4.00 g of tri-
azole XVIII, 5.06 g of diphenylmethyl chloride, and
3.50 g of K2CO3 in 25 ml of acetone as described for
compound II and purified by recrystallization from
2-propanol.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 3 2004
Tolstyakov
