4
36 J . Org. Chem., Vol. 67, No. 2, 2002
Miller and Salvador
completed. In another earlier work,5 electron-transfer
chemistry was described for the photoreaction between
alcohols and 1-bromo and 1-iodonorbornanes. In that
work the reactivity was attributed to bond homolysis
followed by electron-transfer; however, wavelength de-
pendence studies were not completed, nor was the
analogous photochemistry of alkyl chlorides investigated.
of the solution was occasionally measured and did not rise
above 30 °C. The solution was then transferred to a 50 mL
round-bottom flask and reduced in volume by rotary evapora-
tion to give a wet solid. The reaction products were isolated
by preparatory gas chromatography using a Varian 2700 fitted
with a 1/4 in. packed methyl silica column and a thermal
conductivity detector. Separation was effected by the isother-
mal heating of the column to 170 °C with a flow rate of 6 mL/
min of He. The 1-adamantyl methyl ether was collected as a
flaky white powder in a U-tube cooled in liquid nitrogen.
The reaction of 1-bromoadamantane in liquid ammonia
to yield 1-adamantaneamine has also been reported.6
9
Spectroscopic analysis was consistent with literature values.
That was a side reaction observed during an investigation
of the photocatalyzed SRN1 reaction of thiolates with the
1
H NMR (400 MHz, CDCl
3
) [δ (ppm)]: 1.25 (3H, s), 1.67 (6H,
) [δ
ppm)]: 31.2, 36.9, 40.7, 48.5, quaternary carbon not observed.
IR (KBr): 2912 (s), 2846, 1674 (s), 1389, 1257 (w), 1098, 1025
(w), 806 (w), 661 (w) cm-1
s), 2.13 (6H, s), 3.23 (3H, s). 13C NMR (400 MHz, CDCl
(
3
1
-bromoadamantane; the liquid ammonia was the sol-
vent, selected for its electron solvation properties, and
the mechanism for formation of the 1-adamantylamine
was not addressed.
.
1
-Ad a m a n t yl ter t-Bu t yl E t h er . A 5.8 g amount of 1-
A variety of reactions of halogenated bridgehead
carbons, most notably 1-iodoadamantane and 1-bromo-
adamantane, with molecules containing group 15 and 16
heteroatoms have been documented. Organic derivatives
of phosphorus, arsenic, and antimony as well as selenide
and telluride compounds have been shown to undergo
bromoadamantane was dissolved in 10 mL of neat tert-butyl
alcohol in the 20 mL quartz-capped reaction vessel described
above. The solution was irradiated by a 1000 W Hg/Xe arc
lamp for 144 h, resulting in a dark yellow solution. Product
isolation was effected by preparatory gas chromatography as
for the 1-adamantyl methyl ether. The isolated 1-adamantyl
tert-butyl ether was collected as solid white needles in a liquid-
7
S
RN1 radical substitution reactions with 1-haloadaman-
nitrogen-cooled U-tube. Spectroscopic analysis was consistent
8
9 1
tanes. The reaction mechanisms were elucidated using
free radical inhibitors and observing the effect such
compounds had on the rates of the reactions and the
product distributions. Radical inhibitors were found to
retard the rate of formation of group 15 and 16 substitu-
tion products for third-row and higher elements.
It might be presumed from these trends that the
formation of bridgehead ethers and amines could also
proceed by the SRN1 or another radical mechanism. We
found that this was not the case. Instead, the rich and
potentially useful and controllable class of photoinduced
substitution reactions described in Scheme 1 was in-
volved.
with literature values. H NMR (400 MHz, CDCl ) [δ (ppm)]:
3
1
3
1.2 (3H, s), 1.5 (6H, m), 1.62 (9H, s), 2.1 (6H, s). C NMR (400
MHz, CDCl ) [δ (ppm)]: 29.5 (3C, s), 31.5 (3C, s), 35.5 (3C, s),
5.7 (3C, s), 68.5 (1C, s), second quaternary carbon not
observed. IR (KBr): 2929 (s), 2844 (s), 1729, 1635 (w), 1453,
3
4
-1
1
379 (w), 1271 (w), 744, 693 cm .
N,N-Di-1-a d a m a n tyl-ter t-bu tyla m in e. A 5 g amount of
-bromoadamantane was dissolved in 10 mL of neat tert-
1
butylamine. The solution was irradiated for 96 h by a 1000 W
Hg/Xe lamp in the 20 mL quartz-capped cylindrical reactor
described above. A white solid precipitated during irradiation.
The precipitate was filtered out and retained for further
identification. The supernatant was reduced in volume by
rotary evaporation to yield a wet solid. This solid was redis-
solved in 5 mL of pentane and the N,N-di-1-adamantyl-tert-
butylamine reaction product isolated as a white powder by
preparatory gas chromatography as for the 1-adamantyl
Exp er im en ta l Section
1
methyl ether. H NMR (200 MHz, CDCl
3
) [δ (ppm)]: 1.20 (9H,
tert-Butylamine (Aldrich, 98%), tert-butyl alcohol (Fisher,
9%), methanol (Aldrich, HPLC grade), methylamine (Aldrich,
.0 M in THF solution), 1-chloroadamantane (Aldrich 98%),
cyclohexane (Aldrich, spectrophotometric grade), and pentane
Aldrich, HPLC grade) were obtained and used without further
purification, except for tert-butylamine, which was fractionally
distilled at atmospheric pressure prior to use. Other com-
pounds were prepared as described.
Nuclear magnetic resonance spectra were obtained using
either a Bruker 200 MHz or a J EOL Eclipse 400 MHz
instrument. Infrared spectra were obtained using a Nicolet
DX-5 with sample prepared as pressed KBR pellets. Gas-
chromatography/mass spectra were obtained using a HP 5890
GC/MS. Analytical gas chromatography was performed on a
Varian 3700 gas chromatograph fitted with a methyl silica
capillary column and flame ionization detector.
s), 1.60 (6H, s), 1.75 (6H, d, J ) 4 Hz), 2.00 (3H, s), 2.3 (1H,
broad). 13C NMR (200 MHz, CDCl
) [δ (ppm)]: 23.32, 26.33,
30.09, 40.3, quaternary carbons not observed. IR (KBr): 3410
9
2
3
-
1
(br), 2915, 2849, 1453, 1260, 1088, 1021, 799 cm .
(
The filtered precipitate was dissolved in methanol, treated
with base, and determined by gas chromatographic analysis
to be a mixture composed primarily of the tert-butylamine
starting material and a small amount of the N,N-di-1-ada-
mantyl-tert-butylamine. Thus, the precipitates were identified
as the hydrogen bromide salts of the amine starting material
and the amine product.
N,N-Di-1-a d a m a n t ylm et h yla m in e. A 5 g amount of 1-
bromoadamantane was dissolved in ca. 10 mL of a 2.0 M
solution of methylamine in tetrahydrofuran. This solution was
irradiated for 96 h by a 1000 W Hg/Xe lamp in the 20 mL
quartz-capped cylindrical reactor described above. A white
solid precipitated during irradiation. The precipitate was
filtered out and retained for further identification. The super-
natant was reduced in volume by rotary evaporation to yield
a wet solid. This solid was redissolved in 5 mL of pentane and
the N,N-di-1-adamantylmethylamine product isolated as a
white powder by preparatory gas chromatography as for the
1
-Ad a m a n tyl Meth yl Eth er . A 5 g amount of 1-bromoada-
mantane was dissolved in 10 mL of 10:1 methanol-pentane
and the solution placed into a 20 mL glass cylindrical reaction
vessel capped on both ends with quartz plates. The solution
was irradiated by a 1000 W Hg/Xe arc lamp for 96 h, which
resulted in a dark yellow solution. The unfiltered lamp output
was defocused to fill the endcap area of the reaction vessel,
which was approximately 1 m from the lamp. The temperature
1
N,N-di-1-adamantyl-tert-butylamine above. H NMR (200
MHz, CDCl ) [δ (ppm)]: 1.50 (3H, s), 1.61 (6H, s), 1.64 (6H,
3
s), 2.13 (3H, s), amine hydrogen not observed. 13C NMR (200
MHz, CDCl
3
) [δ (ppm)]: 25.8, 28.3, 32.0, 43.1, quaternary
(
(
5) Poindexter, G. S.; Kropp, P. J . J . Am. Chem. Soc. 1974, 96, 7142.
6) Palacios, S. M.; Santiago, A. N.; Rossi, R. A. J . Org. Chem. 1984,
carbon not observed. IR (KBr): 3403 (br), 2915, 2849, 1653,
1453, 1260, 1088, 1021, 799 cm .
-
1
4
4
4
9, 4609.
(7) Palacios, S. M.; Alonso, R. A.; Rossi, R. A. Tetrahedron 1985,
1, 4147.
(8) Rossi, R. A.; Palacios, S. M.; Santiago, A. N. J . Org. Chem. 1982,
(9) Masada, H.; Yamamoto, F.; Okuda, T. Nippon Kagaku Kaishi
1996, 508.
7, 4654.