Preparation of diamines of adamantane and diamantane from the diazides

Article abstract of DOI:10.1080/00397910600636600

A novel synthetic method for preparing diaminodiamondoids from diazidodiamondoids starting from the hydrocarbons is described. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910600636600

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Preparation of Diamines of Adamantane and
Diamantane from the Diazides
Matthew C. Davis a & David A. Nissan a
a Chemistry and Materials Division, (Code 498220D), Michelson Laboratory,
Naval Air Warfare Center Weapons Division, China Lake, California, USA
Published online: 16 Feb 2007.
To cite this article: Matthew C. Davis & David A. Nissan (2006): Preparation of Diamines of Adamantane and
Diamantane from the Diazides, Synthetic Communications: An International Journal for Rapid Communication
of Synthetic Organic Chemistry, 36:15, 2113-2119
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Synthetic Communicationsw, 36: 2113–2119, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910600636600
Preparation of Diamines of Adamantane
and Diamantane from the Diazides
Matthew C. Davis and David A. Nissan
Chemistry and Materials Division, Michelson Laboratory, Naval Air
Warfare Center Weapons Division, China Lake, California, USA
Abstract: A novel synthetic method for preparing diaminodiamondoids from diazido-
diamondoids starting from the hydrocarbons is described.
Keywords: Adamantane, azidotrimethylsilane, diamantane, diamines, diazides,
dibromides
A program to find new high-strength polymeric materials required the three
diamines: 1,3-diaminoadamantane (3).[1–4] 1,6-diaminodiamantane (6),[5]
and 4,9-diaminodiamantane (9).[6,7] These diamines have been previously
prepared by the Ritter reaction on the corresponding dibromides followed
by hydrolysis. Although the Ritter reactions proceed to give excellent
yields, the subsequent hydrolyses of the amide products required forcing con-
ditions and long reaction times. The yields of the diamines were low in our
hands. Therefore, a method was sought that would give these products
quickly and in good yield.
A literature survey found the convenient method of Prakash et al.[8] to
transform bromoadamantane and bromodiamantanes into the corresponding
azides by Lewis acid–mediated exchange with azidotrimethylsilane.
Because alkylazides are readily reduced to amines, we imagined then that
Prakash et al.’s chemistry[8] on dibromodiamondoids and subsequent
reduction would be an alternate route to 3, 6, and 9 (see Fig. 1).
Received in the USA January 27, 2006
Address correspondence to Matthew C. Davis, Chemistry and Materials Division,
(Code 498220D), Michelson Laboratory, Naval Air Warfare Center Weapons
Division, China Lake, CA 93555, USA. Fax: 001 760 939 1617; E-mail: matthew.
davis@navy.mil
2113

2114
M. C. Davis and D. A. Nissan
Figure 1. Reagents and conditions: a) Br2, Fe, freon 113, 0 8C to rt; b) N3Si(Me)3,
CH2Cl2, SnCl4, reflux; c) H2, Pd/C, THF; d) Br2, reflux; and e) Br2 AlBr3.
The dibromides 1,[9–11] 4,[12,13] and 7[12,14,15] were prepared according to
literature procedures with slight modifications. Of the two iron-catalyzed
methods, Rahkimov et al.’s method[9] was preferred to Likhotvorik et al.’s
method[10] to make 1 because it does not require excess bromine. Both
these methods were better than Denmark et al.’s more recent two-step
process,[11] which uses aluminum bromide and was difficult to control. For
4, the procedure of Chern and Wang[13] was used, and although the yield
was low, the isolation and purification of the product was simple.
In the azide/bromide exchange, the reactions required reflux with an
excess of azidotrimethylsilane for completion. Progress was determined by
thin-layer chromatography. The three previously unknown diazides 2, 5,
and 8 were all solids (see Table 1). For reduction of the diazides, catalytic
hydrogenation was used, which gave the diamines in high yield and purity.
Because 3 is known to react with atmospheric carbon dioxide and water, it
was immediately converted to the stable oxalate salt.
In conclusion, a reliable, three-step method to prepare three known
diamines of adamantane and diamantane is reported. The key step was
transformation of dibromodiamondoids into diazidodiamondoids. Overall
yields of 3, 6, and 9 from the hydrocarbons were 51%, 39%, and 51%,
respectively.
EXPERIMENTAL
Melting points were collected on an electrothermal capillary melting-point
apparatus and are not corrected. NMR spectra were obtained on a Bruker
AC-200 spectrometer (1H at 200 MHz, 13C at 50 MHz) and are referenced
to solvent or tetramethylsilane. Iron powder (325 mesh) was purchased

Diamines of Adamantane and Diamantane
2115
Table 1. Some physical properties and yields of the bromides, azides, and amines
prepared
50 MHz 13C
(CDCl3) C-X
Compound
Yield (%)
Mp (8C)
1
2
3
4
5
6
7
8
9
75
74
93
45
88
99
57b
92
97
100–103
27–28
nd
62.40
59.89
55.41a
75.02
62.29
49.99a
63.29
57.48
45.98
262–265
87–90
312–315
320–323
125–127
220–222
aSolvent C6D6; nd ¼ not determined.
bReferences 12, 14, and 15; X ¼ Br, N3 or NH2.
from Alfa Products (Andover, MA). MolecularDiamondw diamantane (99%)
was provided by MolecularDiamond Technologies, a subsidiary of Chevron
Technology Ventures, LLC (Richmond, CA). Freon 113 (1,1,2-trichloro-
1,2,2-trifluoroethane) and all other reagents and solvents were obtained
from Sigma-Aldrich (Milwaukee, WI) and used as received. The preparation
of 4,9-dibromodiamantane (7)[12,14,15] will be published elsewhere.
1,3-Dibromoadamantane (1)
A 250-mL, single-necked, round-bottomed flask was charged with a magnetic
stirbar and equipped with a Claisen head and a 50-mL pressure-equalizing
addition funnel. The addition funnel and open neck of the Claisen were
adapted with tubing to a moderate N2 flow whereby N2 entered the reactor
at the addition funnel and exited at the Claisen to a gas scrubbing bottle con-
taining aqueous NaOH. A diagram of a similar setup was published pre-
viously.[16] The flask was charged with 20 g of pulverized adamantane
(0.147 mol), 800 mg of Fe powder (0.015 mol, 0.1 equiv) and 60 mL of
Freon 113 and set to stir at rt. The addition funnel was charged with
16.7 mL of Br2 (0.323 mol, 2.2 equiv). The Br2 was added over 30 min.
After 15 min, evolution of HBr began. The internal temperature of the
reaction remained at rt throughout. After 3 h, the reaction was partitioned
between 200 mL of crushed ice and H2O and 100 mL of CHCl3. The
organic phase was separated and washed once with saturated aqueous
NaHCO3 and brine and finally dried over anhydrous MgSO4. The solvent
was evaporated, leaving a tan solid. The solid was slurried with 100 mL of
MeOH and filtered to obtain 32 g of crude product (75%). The compound

2116
M. C. Davis and D. A. Nissan
crystallized as white leaflets from MeOH. It could also be recrystallized from
DMF, DMSO, EtOH, or MeCN. Mp 100–103 8C (lit.[10] 110–111 8C). dH
(CDCl3): 2.87 (s, 2H), 2.37–2.2 (m, 10H), 1.70 (m, 2H); dC (CDCl3):
62.40, 59.18, 47.18, 35.21, 33.71. Anal. calcd. for C10H14Br2: C, 40.85; H,
4.8. Found: C, 40.96; H, 4.78.
1,3-Diazidoadamantane (2)
A mixture of 4 g 1 of (0.014 mol), 12 mL of azidotrimethylsilane (10.44 g,
0.09 mol, 6.5 equiv) and 4 mL of SnCl4 (8.8 g, 0.034 mol, 2 equiv) in 50 mL
of CH2Cl2 was refluxed under N2 for 12 h. After this time, TLC indicated all
dibromide and mono-substituted intermediate were consumed. The mixture
was poured onto 100 mL of crushed ice and H2O. The mixture was stirred
for 30 min and then separated. The organic phase was washed with 50 mL of
H2O, 50 mL of saturated aqueous NaHCO3, and finally 50 mL of brine and
then dried over anhydrous MgSO4. The solvent was evaporated (10 Torr, rt)
to leave a colorless liquid. The liquid was dissolved in 50 mL of hexanes and
passed through a short plug of silica gel to remove a tin by-product (which
was trapped at the origin). The solvent was evaporated. The crude liquid recrys-
tallized from hexanes at 220 8C, and the crystals were collected on a medium-
porosity glass frit at rt. The colorless crystals (2.2 g, 74%) were stored at
220 8C until further use. Mp 27–28 8C. dH (CDCl3): 2.37–2.23 (bs, 2H),
1.76 (s, 2H), 1.73–1.66 (m, 8H), 1.58–1.49 (m, 2H); dC (CDCl3): 59.89,
45.71, 40.31, 34.51, 30.48. Elemental analysis was not performed.
1,3-Diaminoadamantane (3) and 1,3-Diaminoadamantane
bis-Oxalic Acid Salt
A mixture of 2.2 g of 2 (0.01 mol) and 300 mg of 5% Pd on carbon catalyst in
50mL of THF (containing 240 ppm of BHT) was hydrogenated (40 psig) in a
Parrw apparatus at rt for 22h. Hexane (25 mL) was added to the mixture before
filtering through diatomaceous earth on a coarse glass frit. The addition of
hexanes ensured complete removal of the catalyst by a single filtration.
Otherwise, a small amount of catalyst was invariably entrained. The solvent
was evaporated, leaving 1.56g of the title compound as a white solid (93%).
dH (C6D6): 1.97 (m, 2H), 1.37–1.24 (m, 10H), 1.20 (s, 2H), 0.73 (bs, 4H); dC
(C6D6): 55.41, 49.19, 45.54, 35.43, 31.07. The crude 1,3-diaminoadamantane
was dissolved in 50mL of Et2O and magnetically stirred at rt while a solution
of 1.58g of oxalic acid (0.017mol, 2 equiv) in 50mL of Et2O was added
dropwise. A white solid precipitated. The solid was collected on a medium
glass frit and dried under vacuum (2.8g, 92%). Mp .300 8C. dH (D2O): 2.47
(m, 2H), 2.08 (s, 2H), 2.03–1.82 (m, 8H), 1.71 (m, 2H). Anal. calcd. for
C14H22N2O8: C, 48.5; H, 6.35; N, 8.08. Found: C, 48.2; H, 6.53; N, 7.88.

Diamines of Adamantane and Diamantane
1,6-Dibromodiamantane (4)
2117
A 1-L, two-neck, round-bottomed flask was charged with 500 g of Br2 and a
magnetic stirbar. The flask was equipped with a condenser and screw-feed
powder addition funnel. The openings of the apparatus were connected with
tubing to a flow of N2 and a gas scrubbing bottle as described in the
procedure for 1. The flask was cooled in an ice bath and magnetically
stirred. The addition funnel was charged with 50 g of diamantane
(0.26 mol). The solid was added in portions with a screw-feed powder
addition funnel (1 h). After stirring 2 h, the cooling bath was removed and
the flask was heated to reflux for 12 h. The mixture was cooled, a distillation
head was attached to the flask, and the Br2 was distilled at atmospheric
pressure. The flask was cooled, and semisolid residue was partitioned
between 500 mL of CHCl3 and 500 mL of H2O. Some NaHSO3 was added
with stirring to remove the residual Br2, making a light yellow organic
solution. The organic phase was separated and washed with 250 mL of
H2O, 250 mL of saturated aqueous NaHCO3, and finally 250 mL of brine.
The organic phase was dried over anhydrous MgSO4 and evaporated to a
solid. The solid was slurried with 200 mL of hexanes and filtered on a
coarse-porosity glass frit. The crude, off-white solid was .90% pure by
NMR. The crude product was recrystallized from 1,4-dioxane to give
colorless rods (40.5 g, 45%). It can also be recrystallized from DMF,
DMSO, toluene, or MeCN. Mp 262–2658C (lit.[13] 272–273 8C). dH
(CDCl3): 2.59–2.43 (m, 8H), 2.37 (s, 4H), 1.96 (m, 2H), 1.70
(d, J ¼ 13.1 Hz, 4H); dC (CDCl3): 75.02, 52.27, 49.09, 34.34, 30.64. Anal.
calcd. for C14H18Br2: C, 48.58; H, 5.24. Found: C, 48.86; H, 5.36.
1,6-Diazidodiamantane (5)
Procedure similar to 2 using 9 g of 4 (0.026 mol), 22 mL of azidotrimethylsilane
(19.6 g, 0.17 mol, 6.5 equiv), and 6.1 mL of SnCl4 (13.5 g, 0.05 mol, 2 equiv).
The compound crystallized as colorless leaflets from MeCN (6.34 g, 88%). Mp
87–90 8C. dH (CDCl3): 2.18–2.03 (m, 6H), 1.91 (s, 4H), 1.87–1.81 (m, 4H),
1.46 (d, J ¼ 11.9 Hz, 4H); dC (CDCl3): 62.29, 41.35, 41.25, 31.69, 27.83.
Anal. calcd. for C14H18N6: C, 62.2; H, 6.71. Found: C, 62.38; H, 6.59.
1,6-Diaminodiamantane (6)
A mixture of 6.34 g of 5 (0.023 mol) and 700 mg of 5% Pd on carbon catalyst
in 50 mL of THF (containing 240 ppm of BHT) was hydrogenated (40 psig) at
rt for 22 h. Hexanes (50 mL) were added to the mixture before filtering through
diatomaceous earth on a coarse glass frit. The addition of hexanes ensured
complete removal of the catalyst by a single filtration. Otherwise, a small

2118
M. C. Davis and D. A. Nissan
amount of the catalyst was invariably entrained. The solvent was evaporated,
leaving a crude, white solid (5.0 g, 99%) that was pure by NMR. The material
crystallized as colorless leaflets from MeCN. Mp 312–315 8C (lit.[5] 324 8C).
dH (C6D6): 2.11 (d, J ¼ 13.0 Hz, 4H), 1.79 (pentet, J ¼ 2.5 Hz, 2H), 1.41–
1.32 (m, 8H), 1.26 (d, J ¼ 13.0 Hz, 4H), 0.77 (bs, 4H); dC (C6D6): 49.99,
48.34, 45.21, 32.56, 29.47. Anal. calcd. for C14H22N2: C, 77.01; H, 10.16.
Found: C, 76.91; H, 10.13.
4,9-Diazidodiamantane (8)
The procedure is similar to that used for 2, using 3.9 g of 7 (0.011 mol), 9.5 mL
of azidotrimethylsilane (8.2 g, 0.07 mol, 6.5 equiv), and 2.36 mL of SnCl4
(5.2 g, 0.02 mol, 2 equiv). The compound crystallized as colorless leaflets
from MeCN (2.78 g, 92%). Mp 125–127 8C. dH (CDCl3): 1.97 (s, 6H), 1.83
(s, 12H); dC (CDCl3): 57.48, 41.08, 37.73. Anal. calcd. for C14H18N6: C,
62.2; H, 6.71. Found: C, 61.55; H, 6.32.
4,9-Diaminodiamantane (9)
A procedure similar to that used for 6, using 2.78 g of 8 (0.01 mol), gave a
quantitative yield of crude product. The material crystallized as colorless
microcrystals from MeCN (2.2 g, 97%). Mp 220–222 8C (lit.[6] 238–
2408C). dH (CDCl3): 1.81 (s, 6H), 1.60 (s, 12H), 1.25 (bs, 4H); dC (CDCl3):
45.98, 45.81, 38.04. Anal. calcd. for C14H22N2: C, 77.01; H, 10.16. Found:
C, 76.41; H, 10.03.
ACKNOWLEDGMENTS
Financial support from the Office of Naval Research is gratefully recognized.
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