4464 J . Org. Chem., Vol. 61, No. 13, 1996
Notes
yielded 15 (0.72 g, 88%): lit.11 mp 214-216 °C11; 1H NMR (500
MHz, CD3COCD3) δ 3.0 (br, 1H, OH variable), 7.05 (dd, 1H, Ph-
H), 7.4 (dd, 1H, Ph-H), 7.56-7.61 (m, 2H, Ph-H), 9.1 (br, 1H,
Ph-H), 15.7 (br, 1H, NH); MS 162, 134, 119, 107, 91, 79, 65; exact
mass for C7H6N4O, m/ e (calcd) 162.0542, m/ e (obsd) 162.0555.
Anal. Calcd for C7H6N4O: N, 34.55. Found: N, 34.22.
volatile products in the indicated yields. The method is
much cleaner than pyrolysis of 8 and is being extended
to practical synthesis of analogs and derivatives of 10.
Finally, the mechanistic principles in the thermal con-
versions of 34 to 10 and 11 are identical with those found
for 9.
5-(4-Hyd r oxyp h en yl)tetr a zole (9). 4-Cyanophenol (13),
sodium azide, and boron trifluoride etherate as for 17 gave 9
(0.44 g, 54%): mp 234-238 °C, lit.10b,12 mp12 239-241 °C; 1H
NMR (500 MHz, CD3COCD3) δ 2.95 (br, 1H, NH), 7.02 and 7.95
(AB q, 4H, J AB ) 11.5 Hz), 10.1 (br, 1H, OH); MS 162, 134, 119,
107, 91, 79, 69, 65, 51; exact mass for C7H6N4O, m/ e (calcd)
162.0542, m/ e (obsd) 162.0538. Anal. Calcd for C7H6N4O: N,
34.55. Found: N, 34.39.
P yr olysis of 9. The products of volatization of 9 (320 mg, 2
mmol) through a packed quartz tube (3 × 35 cm) at 1.8 mmHg
at 620 °C were trapped at -78 °C. Addition of hexane (50 mL)
to the pyrolysate and filtration gave 4-cyanophenol (13, 71 mg,
0.6 mmol, 30%), identified by comparison with an authentic
sample. The filtrate was concentrated under reduced pressure
at room temperature. Gas chromatographic analysis (7.5% QF-1
Chromosorb, 10 in. × 1/4 in. column, 140 °C) of the concentrate
revealed the presence of benzaldehyde (11, ∼6%), tropone (10),
and o-cresol (12).
The concentrated solution was flash column-chromatographed
on silica gel using 1:1 methylene chloride:hexane (400 mL), 3:1
methylene chloride:ethyl acetate (500 mL), and 1:1 methylene
chloride:ethyl acetate (300 mL) as eluents. Separation and/or
analyses of the products yielded: (1) 11 (10 mg, 0.096 mmol,
5%), identified by its IR absorption and conversion to authentic
benzaldehyde (2,4-dinitrophenyl)hydrazone, (2) 10 (49 mg, 0.46
mmol, 23%), assigned by comparison of its Rf value and IR
absorption with an authentic sample, (3) 12 (5-8%) as identified
chromatographically by comparison with an authentic sample,
and (4) an unidentified red product (C14H12O2, 120 mg) which is
homogeneous by thin layer chromatography, has hydroxyl (OH,
3400 cm-1) and weak carbon-carbon double bond IR absorp-
tions, changes to dark brown with decomposition on heating,
thin layer chromatography, or crystallization from ethanol, and
exhibits 1H NMR (CD3COCD3) at δ 3.2 (br s), 6.95, and 8.22-
8.45 (br).4
Exp er im en ta l Section
Melting points were determined in capillaries and are uncor-
rected. The H NMR of all compounds of the present study are
1
reported on the δ scale in parts per million from tetramethyl-
silane in CDCl3. Elemental analyses were conducted by Micro
Analyses, Wilmington, DE. All reagents and solvents were dried
and purified, and subsequent reactions were conducted under
argon when deemed necessary.
P yr olysis of 15. Thermolysis of 15 at 800 °C/1.5 Torr and
product isolation as described for 9 yielded 10 (4-5%) and
3-cyanophenol (16, >50%) along with initial 15 (>25%) and
involatile products. Similar results were obtained on volatiza-
tion of 15 through glass-packed tubes at different temperature
and pressures. On dropping solid 15 into vertical pyrolysis tubes
at 650 °C/0.1 Torr, 10 (1%), 12 (1%), and phenol (1%) along with
16 (84%) were obtained.
5-(2-Hyd r oxyp h en yl)tetr a zole (17). To 2-cyanophenol (18,
0.6 g, 5 mmol) and sodium azide (0.54 g, 8 mmol) in anhydrous
dimethylformamide (15 mL) under argon was added boron
trifluoride (0.10 g, 1.60 mmol) in ethyl ether (1.2 mL). The
mixture was refluxed 24 h, concentrated under reduced pressure,
cooled, diluted with water, neutralized, and filtered to separate
the 17 that precipitated. The filtrate was diluted with water (5
mL). Acidification with concentrated hydrochloric acid to pH
2, storage (24 h), and separation gave additional 17. The mother
liquor, after vacuum concentration, addition of ethanol to
precipitate the sodium chloride and excess sodium azide, evapo-
ration to dryness, addition of water (5 mL) and dilute hydro-
chloric acid, and storage at 0-5 °C, yielded additional 17. After
crystallization from water, the combined 17 (0.72 g, 89%) melted
at 225-226 °C, lit.10 mp 221-222 °C: 1H NMR (500 MHz, CD3-
COCD3) δ 3.0 (br, 1H, OH variable), 7.09 (dd, 1H, Ph-H4), 7.14
(d, 1H, Ph-H3), 7.47 (dd, 1H, Ph-H5), 8.12 (d, 1H, Ph-H6), 10.6
(br, 1H, NH); MS 162, 134, 119, 105, 91, 78, 64, 51; exact mass
for C7H6N4O, m/ e (calcd) 162.0542, m/ e (obsd) 162.0541. Anal.
Calcd for C7H6N4O: N, 34.55. Found: N, 34.96.
P yr olysis of 17. Flash vacuum decompositions of 17 at 650-
710 °C at 1.5-2.0 Torr as for 9 gave 10 (∼1%), 12 (∼1%),
2-cyanophenol (18, 49-75%), phenol (∼1%), and intractables
along with 17 (up to 25% recovery). Such experiments were
conducted at various temperatures and contact times. The
principal reaction was always decomposition of 17 to 14 and 18.
4-Acetoxyben zyl Aceta te (30). Triethylamine (3 mL) was
added to a solution of 4-hydroxybenzyl alcohol (1.24 g, 11.5
mmol), acetic anhydride (4.1 mL, 44 mmol), and 4-(N,N-
dimethylamino)pyridine (DMAP, 100 mg) in methylene chloride
(50 mL). The mixture was stirred for 2.5 h, extracted with
water, hydrochloric acid (2.4 N), and saturated aqueous sodium
bicarbonate, and then dried over anhydrous potassium carbon-
ate. Concentration of the extract, filtration through silica gel,
elution with ethyl acetate:hexane (1:3), and evaporation of the
eluents yielded 30 (1.95 g, 95%):12 1H NMR (CDCl3) δ 1.9 (s, 3H),
5-(3-Hydr oxyph en yl)tetr azole (15). Reaction of 3-cyanophe-
nol (16), sodium azide, and boron trifluoride etherate as for 17
2.13 (s, 3H), 4.23 (s, 2H), 6.8-7.2 (AB q, 4H); IR (KBr, cm-1
)
(9) Slow addition of the dry sodium salt of 4-hydroxybenzaldehyde
(p-toluenesulfonyl)hydrazone to a vertical glass-packed column at 800
°C/0.1 Torr results in formation of phenol (49%), 10 (4-5%), 12 (4%),
and less volatile products. The dry sodium salt of 2-hydroxybenzalde-
hyde (p-toluenesulfonyl)hydrazone at 650 °C/0.1 Torr yields phenol
(39%), 10 (∼1%), 12 (9%), and high molecular weight derivatives. These
systems are based on generation of and decomposition diazo(4-
hydroxyphenyl)methane and diazo(2-hydroxyphenyl)methane and are
of interest because of formation of phenol rather than 10 and 12.
(10) (a) Brower-Van Straaten, B.; Solinger, D.; Vande Westeringh,
C.; Veldstra, H. Recl. Trav. Chim. 1958, 77, 1129. (b) Kaczmarek, J .;
Smagowski, H.; Grzonka, Z. J . Chem. Soc., Perkin Trans. 2 1979, 12,
1670.
1760, 1740 (>CdO); MS+ calcd 208, MS+ found 208.13
4-Hyd r oxyben zyl Meth yl Eth er (31). A mixture of 30 (14.9
g, 0.077 mol; prepared as above), anhydrous methanol (200 mL),
and sodium acetate (5.7 g, 0.07 mol) was refluxed under argon
for 3 days and then cooled. Concentration of the mixture,
addition of water, neutralization with sodium bicarbonate,
(11) Carboni, B. Ger. Offen. DE 3, 427, 606, Feb 16, 1985.
(12) Antonowa, A.; Hauptmann, S. Z. Chem. 1976, 16(1), 17.
(13) Culbertson, H. M.; Woodbrey, J . C. Anal. Chem. 37, 8, 1034.