Synthesis of bisbicyclo[1.1.1]pentyldiazene. The smallest bridgehead diazene

Article abstract of DOI:10.1021/jo010212u

Bisbicyclo[1.1.1]pentyldiazene, the smallest bicyclic azo compound, has been synthesized from the precursor [1.1.1]propellane via synthesis of N,N′-bis(bicyclo[1.1.1]pentyl)sulfamide and azoxybicyclo[1.1.1]pentane. The UV absorption of this diazene at 382 nm indicates that the compound is the trans isomer. Conversion to the cis isomer by irradiation was not possible because of attainment of a photostationary state. However, on the basis of the photochemical studies, the absorption of the cis-[1.1.1] isomer is estimated to be 384 nm.

Full text of DOI:10.1021/jo010212u

6282
J . Org. Chem. 2001, 66, 6282-6285
Syn th esis of Bisbicyclo[1.1.1]p en tyld ia zen e. Th e Sm a llest
Br id geh ea d Dia zen e
Md. T. Hossain and J ack W. Timberlake*
Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
Received February 26, 2001
Bisbicyclo[1.1.1]pentyldiazene, the smallest bicyclic azo compound, has been synthesized from the
precursor [1.1.1]propellane via synthesis of N,N′-bis(bicyclo[1.1.1]pentyl)sulfamide and azoxybicyclo-
[1.1.1]pentane. The UV absorption of this diazene at 382 nm indicates that the compound is the
trans isomer. Conversion to the cis isomer by irradiation was not possible because of attainment
of a photostationary state. However, on the basis of the photochemical studies, the absorption of
the cis-[1.1.1] isomer is estimated to be 384 nm.
Sch em e 1
In tr od u ction
Diazenes have been studied since the end of the 19th
century.1 They are often highly colored being intense
orange, yellow, red, blue, or green depending on their
molecular structure and have been used in the dying,
printing, and textile industries. Other uses include
sources of free radicals2 in industrial processes such as
polymerization, cracking, and oxidations, as well as in
biological systems of photosynthesis and biosynthesis.3,4
Diazenes exist in two isomeric forms, the trans and
the less-stable cis isomer. Trans isomers normally are
converted to the thermodynamically less-stable cis forms
photochemically, and when heated, cis isomers can revert
to trans isomers with the release of excess stored energy.5
Thus, light energy is converted into heat energy, and
diazenes can be considered as a source of solar energy.
The cis isomer generally absorbs at a higher wavelength
in the UV spectrum than the corresponding trans isomer.
The highest known absorption for a cis isomer is cis-
azoadamantane at 455 nm.6
on carbons attached to nitrogen have a tendency to
tautomerism.11 Bridgehead diazenes with no R-hydrogen
undergo trans-cis isomerization and are more stable
than their acyclic counterparts. An extensive study of
bridgehead diazenes such as azo-1-adamantane, azo-1-
bicyclo[2.2.2]octane, azo-1-bicyclo[2.2.1]heptane, and azo-
1-bicyclo[2.1.1]hexane was reported in 1982.12 The bulki-
The thermal and photochemical behaviors of diazenes
have been studied since their very early discovery.7
Although, historically, considerable controversy existed
over the decomposition mechanism, whether it is con-
certed or stepwise,8,9 the decomposition is now well-
understood.10 The recent study of the decomposition of
azo methane by Zewail using femtosecond spectroscopy
clearly shows the decomposition to be stepwise.10 The
general mechanisms for decomposition and isomerization
are depicted in Scheme 1. Diazenes having R-hydrogens
ness of the bridgehead group plays an important role in
the isomerization and decomposition.13 The smaller
groups favor isomerization, whereas larger groups as in
1 and 2 undergo isomerization and decomposition to
radicals and nitrogen. The probability of formation of
radical decreases with the smaller R groups.12 According
to Ru¨chardt, the measured rate for formation of radical
is krel(trans,300 °C): cis-ada (1.0), cis-[2.2.2] (0.13), cis-
[2.2.1] (0.008).13
(1) Sandler, S. R; Karo, E. Organic Functional Group Preparations;
Academic Press Inc: New York, 1986; Vol II, p 353.
(2) Pryor, W. A. Free Radicals; McGraw-Hill: New York, 1966; p
129.
(3) Issaces, N. S. Reactive Intermediate in Organic Chemistry;
Wiley: New York, 1975.
(4) Baysal, B.; Tobolsky, A. J . Polym. Sci. 1952, 8, 529.
(5) Engel, P. S.; Wood, J . L.; Sweet, J . A.; Margrave, J . L. J . Am.
Chem. Soc. 1974, 96, 2381.
(6) (a) Prochazka, M.; Ryba, O.; Lim, P. Collect. Czech. Chem.
Commun. 1968, 33, 3387. (b) Timberlake, J . W.; Szilagyi, S.; Page, M.
A.; Melaugh, R. A.; Engel, P. S. J . Am. Chem. Soc. 1976, 98, 1971.
(7) Engel. P. S. Chem. Rev. 1980, 80, 99.
The smallest bridgehead diazene, bisbicyclo[1.1.1]-
pentyldiazene, is not known, although several attempts
to synthesize this diazene12 failed from complexity in
(11) (a) Coates, G. E.; Sulton, L. E. J . Chem. Soc. 1948, 1187. (b)
Mills, T.; Stingham, R. S. Tetrahedron Lett. 1969, 23, 1853.
(12) Chae, W.; Baughman, S. A.; Engel, P. S.; Bruch, M.; O¨ zmeral,
C.; Szilagyi, S.; Timberlake, J . W. J . Am. Chem. Soc. 1981, 103, 4824.
(13) Golzke, V.; George, F.; Oberlinner, A, Ru¨chardt, C. Nouv. J .
Chim. 1978, 17, 594.
(8) Porter, N. A.; Marnett, L. J . J . Am. Chem. Soc. 1973, 95, 4363.
(9) (a) Rampsperger, H. C. J . Am. Chem. Soc. 1929, 51, 2134. (b)
Seltzer, S.; Dunne, F. T. J . Am. Chem. Soc. 1965, 87, 2628.
(10) Diau, E. W. G.; Abou-Zaid, O. K.; Scala, A.; Zewail, A. H. J .
Am. Chem. Soc. 1998, 120, 3245.
10.1021/jo010212u CCC: $20.00 © 2001 American Chemical Society
Published on Web 08/29/2001

Synthesis of Bisbicyclo[1.1.1]pentyldiazene
J . Org. Chem., Vol. 66, No. 19, 2001 6283
Sch em e 2
Sch em e 4
Sch em e 3
Sch em e 5
synthesis of the precursor amine 7 from ester 5 and
resulted in the formation of olefins 8 and 9 (Scheme 2).
This paper reports the synthesis of this diazene from
[1.1.1]propellane.
matography. The Schmidt reaction of 20 provides 1-bicyclo-
[1.1.1]pentylamine hydrochloride19 (12) in up to 87%
yield.
A single-step synthesis of bisbicyclo[1.1.1]pentyldiazene
(23) by oxidative coupling of 1-bicyclo[1.1.1]pentylamine
with iodine pentafluoride20 failed, and only a trace
amount of 23 could be isolated. An alternative approach
was successful. The conversion of 1-bicyclo[1.1.1]pentyl-
amine to N,N′-bis(bicyclo[1.1.1]pentyl)sulfamide (21) was
easily achieved with sulfuryl chloride and triethylamine
in up to 78% yield.21 The hypochlorite oxidation of
sulfamides in the presence of a strong base affords
diazenes.22 However, our repeated attempts always pro-
vided azoxybicyclo[1.1.1]pentane (22) (Scheme 5) along
with a very small quantity of 23. This is the only case of
which we are aware in which an azoxy compound results.
The reduction of 22 with lithium aluminum hydride
(LAH) in ether under mild reaction conditions provides
23 in 87% yield. The UV absorption maximum of 23 is
at 382 nm, and 23 has a molar absorptivity of 22, thus
establishing it as the trans isomer.
In an attempt to synthesize the cis isomer directly by
chemical means using the Engel method,23 we obtained
a mixture of three compounds, 21, 22, and 23. The
preparation of cis-23 by irradiation of the trans isomer
was also unsuccessful. The comparison of 23 with a series
of other bridgehead bicyclic diazenes reveals an interest-
ing correlation (Table 1). The absorption maximum for
trans-23 is 382 nm and is the highest absorption maxi-
mum among the trans bicyclic diazenes. The UV absorp-
tion maxima in the cis series are 444 nm for cis-2, 423
Resu lts a n d Discu ssion
[1.1.1]Propellane (10) has been known since 198214 and
undergoes 1,3 additions at its bridgehead to afford 1,3-
adducts. Pseudohalogens15,16 are probable candidates for
addition to 10, and iodine azide adds to give 3-iodobicyclo-
[1.1.1]pentyl azide (11) in 92% yield.17 Further reduction
of 3-iodobicyclo[1.1.1]propyl azide would provide 1-bicyclo-
[1.1.1]pentylamine because both the iodine and the azide
are reducible. However, with a variety of reducing agents,
the [1.1.1]propellane group fragments. Lithium alu-
minium hydride reduction of 11 in THF affords 3-meth-
ylenecyclobutylamine hydrochloride (13) and reduction
in ether gives 3-chloro-3-methylbutylamine hydrochloride
(14) (Scheme 3).17
The addition of thiophenol to 10 afforded 1-bicyclo-
[1.1.1]pentylphenylsulfide (15) which by lithiation with
lithium di-tert-butylbiphenyl (LDBB) followed by car-
boxylation provided 1-bicyclo[1.1.1]pentyl carboxylic acid
(20) in up to 45% yield (Scheme 4).18 While working on a
larger scale, we have produced up to 55% yield of 20.
Lithiation of 15 yielded the major product 1-bicyclo-
[1.1.1]pentyllithium (16) along with 17, 18, and 19. In
situ carboxylation of the mixture followed by aqueous
workup removed most of the side products, and 1-bicyclo-
[1.1.1]carboxylic acid (20) can be purified by flash chro-
(14) (a) Semmler, K.; Szeimies, G.; Belzner, J . J . Am. Chem. Soc.
1985, 107, 6410. (b) Wiberg, K. B. Chem. Rev. 1989, 89, 975.
(15) Hassner, A.; Matthews, G. J .; Flower, F. W. J . Am Chem. Soc.
1969, 91, 5046.
(16) Fowler, F. W.; Hassner, A.; Levy, L. A. J . Am. Chem. Soc. 1967,
89, 2077.
(19) Wiberg, K. B.; William, V. Z., J r. J . Org. Chem. 1970, 35, 369.
(20) (a) Stevens, T. E. J . Org. Chem. 1961, 26, 2531. (b) Timberlake,
J . W.; Martin, J . C. J . Org. Chem. 1968, 33, 4054.
(21) Timberlake, J . W.; Alender, J .; Garner, A. W.; Hodges, M. L.;
Ozmeral, C.; Szilagyi, S.; J acobus, J . O. J . Org. Chem. 1981, 46, 2082.
(22) Ohme, R.; Preuschof, H.; Heyne, H. U. Org. Syn. 1972, 11, 52.
(23) Engel, P. S. Tetrahedron Lett. 1974, 26, 2301.
(17) Hossain, M. T.; Timberlake, J . W. J . Org. Chem. 2001, 66, 4409.
(18) Wiberg, K. B.; Waddell, S. T. J . Am. Chem. Soc. 1990, 112, 2194.

6284 J . Org. Chem., Vol. 66, No. 19, 2001
Hossain and Timberlake
Ta ble 1. Com p a r ison of UV Absor p tion for Br id geh ea d
Dia zen es
3.0 g of anhydrous aluminum chloride was added. The color
of the solution changed to deep violet. A solution of 17.36 g
(0.19 mol) of 2-chloro-2-methylpropane (tert-butyl chloride) in
20 mL of nitromethane was added dropwise to the stirred
mixture over 30 min. At the end of the addition, the reaction
started vigorously as was evidenced by the evolution of
hydrogen chloride gas through the condenser. The reaction
mixture was stirred overnight and poured onto crushed ice in
a 500 mL beaker. The ice was allowed to melt, and the solution
was warmed to room temperature. The organic layer was
extracted with a mixture of nitromethane/pentane (1:1, 3 ×
50 mL), dried over anhydrous magnesium sulfate, and then
filtered. The light yellow color filtrate was treated with silica
gel (100 g) to provide a colorless solution. Evaporation of the
solvent afforded a white powder which was purified by
crystallization from nitromethane to give white needlelike
crystals of 4,4′-di-tert-butylbiphenyl: 21.0 g, 92%, mp 127.5-
129° C (lit.25 128.6-129 °C). 1H NMR (CDCl3): δ 7.53-7.44
(m, 8H), 1.35 (s, 18H). 13C NMR (CDCl3): δ 127.1, 126.0, 31.6,
0.2.
cis,
λmax
(nm)
cis, ꢀ
trans, trans, ꢀ
com-
pounds
(L mol-1
λmax
(L mol-1
ref-
erence
cm-1
)
(nm)
cm-1
)
2
3
4
444
423
404
(404 - 20) )
384 (calcd)
369
365
371
382
14.7
15.1
21
13, 27
13, 27
13, 27
present
work
123
118
23
22
nm for cis-3, and 404 nm for cis-4. The average difference
in absorption of these cis diazenes from one to the next
is about 20 nm. Thus, the estimated λmax for cis-23 would
be near 384 nm (404 - 20) which is almost the same as
that of the trans isomer. The isolated yield of a cis isomer
from irradiation of the trans isomer decreases as the
bulkiness of the bridgehead group decreases.12 The isola-
tion of cis-2 was not possible because of its lability, and
its formation was indicated only by UV absorption. The
yield of cis-3 was not reported, and cis-4 was isolated in
33% yield.12 As bulkiness of the bridgehead diazene
decreases, the difference in absorption maxima between
cis and trans isomers decreases significantly and the
maxima become almost the same (382 and 384 nm) for
both the cis and trans bisbicyclo[1.1.1]pentyldiazene
isomers. Furthermore, because the molar absorptivity of
cis-23 is expected to be larger than that of trans-23, the
photostationary state that is established would greatly
favor the trans isomer over the cis isomer.
Bicyclo[1.1.1]p en tylp h en ylsu lfid e (15).18 To a solution
of 4.63 mmol of [1.1.1]propellane in ether at 0 °C was added
0.51 g (4.63 mmol) of thiophenol in 15 mL of ether dropwise,
and the mixture was stirred at room temperature for 30 min.
Evaporation of ether under vacuum gave a colorless oil, which
was dissolved in 5 mL of pentane and purified by passing
through a short column of silica gel with pentane. Evaporation
1
of pentane yielded 15 as a colorless oil: 0.75 g, 92%. H NMR
(CDCl3): δ 7.45-7.32 (m, 5H), 2.72 (s, 1H), 1.95 (s, 6H) [lit.18
δ 7.50-7.44 (m, 2H), 7.35-7.25 (m, 4H), 7.23 (s, 1H), 1.96 (s,
6H)].
1-Bicyclo[1.1.1]pen tan e Car boxylic Acid (20).18 An oven-
dried 250 mL three-neck flask, equipped with a glass coated
magnetic stirrer, a condenser, and a rubber septum, was put
under positive pressure of argon. The flask was heated with a
flame by occasional release of the argon from the septum.
When the flask was cool, 16.32 g (61.26 mmol) of 4,4′-di-tert-
butylbiphenyl and 50 mL of dry THF were introduced, and a
positive pressure of argon was maintained throughout the
reaction. Lithium wire was cleaned with a sharp knife in
petroleum ether (bp 40-60 °C) and dried with filter paper,
and 0.42 g (60.52 mmol) was cut, while held in the stream of
argon, into very small pieces with a pair of scissors. The pieces
fell into the flask by gravitation. The funnel was replaced with
a rubber septum, and the mixture was magnetically stirred.
The surface of the lithium wire became shiny, and within 7
min, the solution became dark green. The solution was stirred
at 0 °C under a positive pressure of argon for 4 h, during which
time all of the lithium reacted, and lithium di-tert-butylbi-
phenyl (LDBB) was formed. Into another 250 mL three-neck
flask, which was dried as above, under a positive pressure of
argon were added 5.28 g (29.97 mmol) of 1-bicyclo[1.1.1]-
pentylphenylsulfide (18) and 30 mL of dry THF. The mixture
was stirred and cooled to -78 °C. The freshly prepared lithium
di-tert-butylbiphenyl (LDBB) was cannulated dropwise over
a 30 min period. When the addition was completed, the
reaction mixture was stirred between -65 and -55° C for 1 h
and cooled to -78 °C. A stream of carbon dioxide was bubbled
into the solution using a long needle, and an exit needle vented
the carbon dioxide stream. The solution became colorless
within 5 min, and the carbon dioxide stream was continued
until the solution became milky white and was allowed to
warm to room temperature. The solution became colorless after
evaporation of excess carbon dioxide. A saturated solution of
50 mL of sodium bicarbonate and 50 mL of ether was added
to the stirred solution. The aqueous layer was separated,
acidified with excess hydrochloric acid, and extracted with
ether (3 × 30 mL). The combined organic layers were dried
over anhydrous magnesium sulfate and evaporated to a
colorless oil of two components (TLC). Separation by silica gel
flash chromatography with dichloromethane afforded 20 as a
Con clu sion
Bisbicylo[1.1.1]pentyldiazene has been synthesized by
a multistep process from [1.1.1]propellane. The UV
spectrum indicates that the compound is trans. The
isolation of the cis isomer by irradiation was not possible.
However, on the basis of the study of a series of
bridgehead diazenes, the UV absorption maximum of the
cis [1.1.1]diazene is estimated to be 384 nm. These two
factors, the close proximity of λmax between the cis and
trans isomers and the greater molar absorptivity of the
cis isomer over the trans isomer, resulted in no observa-
tion of any photochemical conversion of the trans isomer
to the cis one in the UV spectrum.
Exp er im en ta l Section
Gen er a l. THF and ether were distilled from sodium and
benzophenone. Pentane was distilled from sodium. Acetonitrile
and triethylamine were distilled from phosphorus pentoxide,
pyridine was distilled from potassium hydroxide, and di-
chloromethane was distilled from calcium sulfate. Thiophenol
was first dried over calcium chloride and then distilled under
reduced pressure with a positive flow of nitrogen. Methanol
was distilled from magnesium. Biphenyl was recrystallized
from methanol. All the solvents after distillation were pre-
served under either 4 Å molecular sieves or potassium
hydroxide and used with a positive pressure of nitrogen.
The syntheses of [1.1.1]propellane24 (10), 3-iodobicyclo-
[1.1.1]pentyl azide (11), 3-methylenecyclobutylamine hydro-
chloride (13), and 3-chloro-3-methylbutylamine hydrochloride
(14) have been described in a previous paper.17
4,4′-Di-ter t-bu tylbip h en yl.25 To 75 mL of nitromethane in
a 250 mL dry three-neck flask equipped with a condenser, an
addition funnel, a magnetic stirrer, and a stopper was added
13.15 g (0.085 mol) of biphenyl. The mixture was stirred, and
white solid: 1.9 g (57%). IR (KBr): 1704 cm-1 1H NMR
.
(CDCl3): δ 2.43 (s, 1H), 2.11 (s, 6H) [lit.22 δ 2.45 (s, 1H), 2.13
(s, 6H)]. 13C NMR (CDCl3): δ 175.7, 51.5, 42.3, 27.8.
(24) Lynch, K. M.; Dailey, W. P. J . Org. Chem. 1995, 60, 4666.
(25) Curtis, M. D.; Allred, A. L. J . Am. Chem. Soc. 1965, 87, 2554.

Synthesis of Bisbicyclo[1.1.1]pentyldiazene
J . Org. Chem., Vol. 66, No. 19, 2001 6285
1-Bicyclo[1.1.1]p en tyla m in e Hyd r och lor id e (12).26 1-Bi-
cyclo[1.1.1]pentane carboxylic acid (23) (1.84 g, 16.41 mmol),
30 mL of chloroform, and 6 mL of concentrated sulfuric acid
were added to a three-neck 100 mL flask equipped with a
reflux condenser, a magnetic stirrer, and a stopper. The
mixture was stirred and heated to 35-40 °C in an oil bath.
Sodium azide (2.17 g, 33.37 mmol) was added to the slowly
stirred solution over 1 h. The solution was cooled to room
temperature and made basic with 33% sodium hydroxide
solution. The basic solution was then steam distilled into an
ice-water receiver. Evaporation of the chloroform and water
afforded a light orange amine salt, which was purified by
crystallization from ethyl acetate-ethanol to give 1-bicyclo-
[1.1.1]pentylamine hydrochloride (12): 1.70 g, (87%); mp 242-
Azoxybicyclo[1.1.1]p en ta n e (22). N,N′-Bis(1-bicyclo-
[1.1.1]pentyl)sulfamide (21) (0.5 g, 2.19 mmol), 60 mL of
pentane, and 20 mL of 5% NaOCl (chlorox) were added to a
250 mL three-neck flask and cooled to 0 °C in an ice bath.
The reaction mixture was stirred for 2 h at 0 °C, the ice bath
was removed, and the mixture was stirred overnight at room
temperature. Completion of the reaction was evidenced by the
disappearance of the sulfamide. The yellow organic layer was
separated from the aqueous layer and washed with water (2
× 20 mL), 5% HCl (2 × 20 mL), and water (10 mL), followed
by drying over anhydrous magnesium sulfate. Evaporation of
the solvent under vacuum gave a yellow solid. The crude solid
was purified by silica gel flash chromatography with pentane,
and evaporation of the solvent under vacuum afforded a light
yellow solid. Further purification was done by recrystallization
from pentane to give azoxybicyclo[1.1.1]pentane (22): 0.23 g
(59%); mp 79.5-80.5 °C. IR (KBr): 3016, 2937, 2897, 1720,
1481, 1357, 1267, 1207 cm-1. 1H NMR (CDCl3): δ 2.58 (s, 1H),
2.54 (s, 1H), 2.27 (s, 6H), 2.23 (s, 6H). 13C NMR (CDCl3): δ
63.1, 56.3, 52.4, 52.1, 26.8, 20.4. UV (pentane) λmax: 233 nm.
Anal. Calcd for C10H14N2O: C, 67.39; H, 7.92; N, 15.72.
Found: C, 67.32; H, 8.03; N, 15.63.
244 °C. 1H NMR (D2O): δ 2.50 (s, 1H), 1.94 (s, 6H) [lit.19
2.61 (1H), 2.06 (6H)]. 13C NMR (D2O): δ 50.9, 44.9, 23.2.
δ
N,N′-Bis(1-bicyclo[1.1.1]pen tyl)su lfam ide (21). 1-Bicyclo-
[1.1.1]pentylamine hydrochloride (12) (1.0 g, 8.35 mmol) was
taken up in 5 mL of 10% NaOH solution, and the free amine
was extracted with dichloromethane (5 × 5 mL). The combined
dichloromethane was dried over KOH for 4 h. An oven-dried
100 mL three-necked flask equipped with a condenser, addition
funnel, and magnetic stirring bar under a positive pressure
of argon was charged with 0.84 g (8.30 mmol) of triethylamine.
Dichloromethane-containing free amine was decanted to the
reaction flask and cooled to -30 to -35 °C in a dry ice-acetone
bath. A solution of 4.18 mL (1 M, 4.18 mmol) of sulfuryl
chloride in dichloromethane was added from the addition
funnel slowly over 30 min, and then the mixture was stirred
for 2 h at the same temperature. It was allowed to warm to
room temperature and stirred overnight. The mixture was
poured into a separatory funnel, washed with 5% HCl (3 × 20
mL), dried over anhydrous magnesium sulfate, and filtered.
Evaporation of the filtrate under vacuum provided a light gray
solid, which was purified by crystallization from ethyl acetate-
water to give N,N′-bis(1-bicyclo[1.1.1]pentyl)sulfamide (21) as
white crystals: 0.74 g (78%); mp 201-203 °C. IR (KBr): 3298,
2985, 2921, 2865, 1498, 1424, 1323, 1267, 1157, 973, 922, 885
Bisbicyclo[1.1.1]p en tyld ia zen e (23). To a stirred slurry
of 0.09 g (2.37 mmol) of lithium aluminum hydride in 25 mL
of dry ether in a 100 mL three-neck flask under argon was
added 0.29 g (1.62 mmol) of azoxybicyclo[1.1.1]pentane (22)
slowly over a 10 min period. When the addition was completed,
the reaction mixture was refluxed gently for 16 h and cooled
to room temperature. The reaction mixture was cooled in an
ice bath, and unreacted lithium aluminum hydride was taken
up with ice cold water (10 mL). The organic layer was
separated, the aqueous layer was extracted with ether (4 ×
20 mL), and the combined organic layers were dried over
anhydrous magnesium sulfate. Evaporation of the solvent
afforded a yellow solid. The solid was purified by recrystalli-
zation from pentane and by sublimation to give bisbicyclo-
[1.1.1]pentyldiazene (23) as yellow crystals: 0.23 g (87%); mp
108-110 °C. 1H NMR (CDCl3): δ 2.58 (s, 1H), 2.10 (s, 6H).
13C NMR (CDCl3): δ 65.7, 51.5, 23.4. UV (pentane) λmax: 382
nm. ꢀ ) 22.4 mol-1 cm-1. Anal. Calcd for C10H14N2: C, 74.02;
H, 8.71; N, 17.27. Found: C, 74.41; H, 8.82; N, 16.90. HRMS:
calcd for C10H14N2, 162.1157; found, 162.1150.
cm-1
6H). 13C NMR (CDCl3): δ 52.6, 48.5, 23.9. Anal. Calcd for
10H16N2O2S: C, 52.60; H, 7.08; N, 12.27. Found: C, 52.72;
.
1H NMR (CDCl3): δ 4.84 (s, 1H), 2.44 (s, 1H), 2.03 (s,
C
H, 7.07; N, 12.22.
(26) Barbachyn, M. R.; Hutchinson, D. K.; Toops, D. S.; Reid, R. J .;
Zurenko, G. E.; Yagi, B. H.; Schaadt, R. D.; Allison, J . W. Bioorg. Med.
Chem. Lett. 1993, 3, 671.
J O010212U