2256 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 11
Martarello et al.
(m, 2H, CH2), 2.53-2.83 (m, 3H, CH2 and CH), 3.48 (d, 2H, J
) 4.8 Hz, OCH2), 4.52 (s, 2H, Ph-CH2-O), 5.15-5.26 (bs, 1H,
NH), 7.27-7.36 (m, 5H, phenyl). Anal. (C18H25NO5): C, H, N.
a n ti-1-[N-(ter t-Bu t oxyca r b on yl)a m in o]-3-b en zyloxy-
m eth yl-1-cyclobu ta n e-1-ca r boxylic Acid (7). Yield 0.28 g
(76%); oil. 1H NMR (CDCl3): δ 1.45 (s, 9H, t-Bu), 2.50-2.53
(m, 4H, CH2 ×2), 2.76-2.85 (m, 1H, CH), 3.54 (d, 2H, J ) 5.6
Hz, OCH2), 4.56 (s, 2H, PhCH2-O), 5.39-5.44 (bs, 1H, NH),
7.27-7.36 (m, 5H, phenyl). Anal. (C18H25NO5): C, H, N.
1-[N-(ter t-Bu toxyca r bon yl)a m in o]-3-ben zyloxym eth yl-
1-cyclobu ta n e-1-ca r boxylic Acid t-Bu tyl Ester s (8 a n d 9).
A solution of tert-butyl 2,2,2,-trichloroacetimidate (0.68 g, 3.1
mmol) and the appropriate isomerically pure protected amino
acid (0.335 g, 1 mmol) in 5 mL of dichloromethane was stirred
15 h at room temperature. The reaction mixture was concen-
trated to dryness and chromatographed on silica gel using CH2-
Cl2/MeOH (98:2).
syn -1-[N-(ter t-Bu t oxyca r b on yl)a m in o]-3-b en zyloxy-
m et h yl-1-cyclob u t a n e-1-ca r b oxylic Acid t-Bu t yl E st er
(8). Yield 1.08 g (89%); mp 52.5 °C (CH2Cl2-MeOH). 1H NMR
(CDCl3): δ 1.42 (s, 9H, NHtBu), 1.48 (s, 9H, CO2tBu), 2.19-
2.26 (m, 2H, CH2), 2.56-2.64 (m, 3H, CH2 and CH), 3.50 (bs,
2H, OCH2), 4.51 (s, 2H, PhCH2O), 5.2 (s, 1H, NH), 7.26-7.37
(m, 5H, phenyl). Anal. (C22H33NO5): C, H, N.
transport in the cellular uptake of these compounds in
a variety of tumor types. An additional goal is the in
vivo measurement of the regional distribution of [18F]-
16 and [18F]17 following intravenous administration in
severe combined immunodeficiency (SCID) mice im-
planted with the human tumor cells to determine their
potential for imaging systemic tumors in humans.
Exp er im en ta l Section
Gen er a l P r oced u r es. All animal experiments were carried
out according to protocols by the Institutional University
Animal Care Committee (IUCAC) and Radiation Safety Com-
mittees of Emory University. All chemicals and solvents were
of analytical grade and were used without further purification.
The [18F]fluoride was produced at Emory University with a
Siemens RDS 112 11 MeV negative-ion cyclotron by the 18O
(p,n) 18F reaction using [18O]H2O (95%). TLC analyses were
performed using either 0.25 mm thick layers of G PF-254 silica
gel adsorbed on aluminum plates or 0.25 mm RP Chiralplates
(Macherey-Nagel from Alltech Co., Deerfield, IL). Merck
Kieselgel 60 was used for column chromatography. The proton
NMR spectra were obtained with a 400 MHz Varian spec-
trometer. The chemical shift values are expressed in δ values
(parts per million) relative to tetramethylsilane as an internal
standard. Elemental analyses were obtained from Atlantic
Microlab Inc., Norcross GA. Meltings points were measured
with an Electrothermal 9100 apparatus (Electrothermal Eng.
Ltd) and are uncorrected. Chromatograms of the radiolabeled
compounds were analyzed with a Bioscan System 200 (Wash-
ington, DC).
a n ti-1-[N-(ter t-Bu t oxyca r b on yl)a m in o]-3-b en zyloxy-
m et h yl-1-cyclob u t a n e-1-ca r b oxylic Acid t-Bu t yl E st er
1
(9). Yield 1.12 g (92%); oil. H NMR (CDCl3): δ 1.43 (s, 18H,
NHt-Bu and CO2tBu), 2.12-2.30 (m, 2H, CH2), 2.34-2.42 (m,
2H, CH2 and CH), 2.70-2.84 (m, 1H, CH), 3.50 (d, 2H, J )
7.2 Hz, OCH2), 4.51 (s, 2H, PhCH2O), 5.2 (s, 1H, NH), 7.26-
7.36 (m, 5H, phenyl). Anal. (C22H33NO5): C, H, N.
1-[N-(ter t-Bu toxyca r bon yl)a m in o]-3-h yd r oxym eth yl-1-
cyclobu ta n e-1-ca r boxylic Acid t-Bu tyl Ester s (10 a n d 11).
A suspension of the benzyl ether (120 mg, 0.31 mmol) and 10%
Pd/C (20 mg) in 10 mL of methanol was stirred under a
hydrogen atmosphere for 3 h. After it was filtered through a
pad of Celite, the filtrate was concentrated to dryness under
reduced pressure and purified via silica column chromatog-
raphy using CH2Cl2/MeOH (98:2).
syn -1-[N -(t er t -B u t o xy c a r b o n y l)a m in o]-3-h y d r o x y -
m et h yl-1-cyclob u t a n e-1-ca r b oxylic Acid t-Bu t yl E st er
(10). Yield 92 mg (100%); oil. 1H NMR (CDCl3): δ 1.43 (s, 18H,
NHtBu and CO2tBu), 2.41-2.65 (m, 5H, CH2-CH-CH2), 3.66
(bs, 2H, CH2OH), 5.49 (s, 1H, NH). Anal. (C15H27NO5): C, H,
N.
syn -an d a n ti-2-[(P h en ylm eth oxy)m eth yl]-5,7-diazaspir o-
[3.4]octa n e-6,8-d ion e (4 a n d 5). To a stirring solution of
ammonium carbonate (11.16 g, 116 mmol) and ammonium
chloride (2.48 g, 46.3 mmol) in 75 mL of water was added a
solution of the ketone 3 (2.2 g, 11.58 mmol) in 75 mL of
ethanol. After 15 min, potassium cyanide (3.4 g, 52.3 mmol)
was added and the reaction mixture was heated at 60 °C for
72 h. The solvent was removed by rotoevaporation. The
resulting solid was stirred in water, and the crude product
was collected by filtration. Chromatography of the crude solid
on silica gel using CH2Cl2/MeOH (97:3) afforded 1.5 g (50%)
of 4, 0.47 g (16%) of 5, and approximately 0.2 g of unresolved
4 and 5.
syn -2-[(Ben zyloxy)m et h yl]-5,7-d ia za sp ir o[3.4]oct a n e-
6,8-d ion e (4). mp 150-151 °C (CH2Cl2-MeOH). 1H NMR
(CDCl3): δ 2.23 (dd, 2H, J ) 13.2 and 6.8 Hz, CH2), 2.52-
2.61 (m, 1H, CH), 2.76 (dd, J ) 12.2 and 9.4 Hz, CH2), 3.48 (d,
2H, J ) 4 Hz, OCH2), 4.57 (s, 2H, Ph-CH2-O), 6.15 (s, 1H,
NH), 7.32-7.40 (m, 5H, phenyl), 7.97 (s, 1H, NH). Anal.
(C14H16N2O3): C, H, N.
a n t i-1-[N -(t er t -Bu t oxyca r b on yl)a m in o]-3-h yd r oxy-
m et h yl-1-cyclob u t a n e-1-ca r b oxylic Acid t-Bu t yl E st er
1
(11). Yield 90 mg (96%); mp 96 °C (CH2Cl2-MeOH). H NMR
(CDCl3): δ 1.45 (s, 9H, NHtBu), 1.50 (s, 9H, CO2tBu), 2.26
(bs, 2H, CH2), 2.40-2.46 (m, 2H, CH2), 2.62-2.74 (m, 1H, CH),
3.68 (d, 2H, J ) 6.4 Hz, CH2OH), 5.11 (s, 1H, NH). Anal.
(C15H27NO5): C, H, N.
a n ti-2-[(Ben zyloxy)m eth yl]-5,7-d ia za sp ir o[3.4]octa n e-
6,8-d ion e (5). mp 173-174 °C (CH2Cl2-MeOH). 1H NMR
(CDCl3): δ 2.35-2.43 (m, 2H, CH2), 2.48-2.55 (m, 2H, CH2),
2.62-2.72 (m, 1H, CH), 3.65 (d, 2H, J ) 9.6 Hz, O-CH2), 4.53
(s, 2H, Ph-CH2-O), 6.37 (s, 1H, NH), 7.25-7.38 (m, 5H,
phenyl), 8.15 (s, 1H, NH). Anal. (C14H16N2O3): C, H, N.
1-[N-(ter t-Bu toxyca r bon yl)a m in o]-3-ben zyloxym eth yl-
1-cyclobu ta n e-1-ca r boxylic Acid s (6 a n d 7). The appropri-
ate isomerically pure hydantoin (0.3 g, 1.1 mmol) was hydro-
lyzed by heating with 13 mL of 3 N NaOH in a closed gas
cylinder at 120 °C for 12 h. The clear yellow solution was
neutralized to pH 6-7 with concentrated HCl and evaporated
to dryness. The residue was extracted with 5 × 10 mL of hot
methanol. Methanol aliquots were combined and evaporated
to dryness. The resulting white solid was treated with di-tert-
butyl dicarbonate (0.5 g, 2.3 mmol) in 10 mL of a mixture
methanol/triethylamine (9:1) at room temperature for 12 h.
The solvent was removed by rotoevaporation, and the crude
product was chromatographed on silica gel using CH2Cl2/
MeOH (95:5).
1-[N-(ter t-Bu toxyca r bon yl)a m in o]-3-m esyloxym eth yl-
1-cyclobu ta n e-1-ca r boxylic Acid t-Bu tyl Ester s (12 a n d
13). To a solution of the appropriate alcohol (90 mg, 0.3 mmol)
and 2,6-lutidine (0.21 mL, 1.83 mmol) in 5 mL of dichlo-
romethane at 0 °C under argon was added dropwise meth-
anesulfonyl chloride (0.094 mL, 1.22 mmol). After 2 h at room
temperature, water was added, and the organic phase was
separated. The organic layer was successively washed with
saturated NaHCO3, cold 1 N HCl, and saturated NaCl. After
the mixture was dried over sodium sulfate and the solvent was
evaporated, the crude residue was purified by column chro-
matography using EtOAc/Hex (1:2).
syn -1-[N -(t er t -Bu t oxyca r b on yl)a m in o]-3-m e syloxy-
m et h yl-1-cyclob u t a n e-1-ca r b oxylic Acid t-Bu t yl E st er
(12). Yield 90 mg (79%); mp 111 °C (EtOAc-Hex). 1H NMR
(CDCl3): δ 1.43 (s, 9H, NHtBu), 1.49 (s, 9H, CO2tBu), 2.38-
2.47 (m, 2H, CH2), 2.58-2.63 (m, 2H, CH2), 2.70-2.80 (m, 1H,
CH), 3.03 (s, 3H, SO2CH3), 4.30 (s, 2H, OCH2), 5.34 (s, 1H,
NH). Anal. (C16H29NO7S): C, H, N.
syn -1-[N-(ter t-Bu t oxyca r b on yl)a m in o]-3-b en zyloxy-
m eth yl-1-cyclobu ta n e-1-ca r boxylic Acid (6). Yield 0.31 g
(84%); oil. 1H NMR (CDCl3): δ 1.43 (s, 9H, t-Bu), 2.05-2.18
a n ti-1-[N-(ter t-Bu t oxyca r b on yl)a m in o]-3-m esyloxy-
m et h yl-1-cyclob u t a n e-1-ca r b oxylic Acid t-Bu t yl E st er
(13). Yield 95 mg (83%); mp 89-90 °C (EtOAc-Hex). 1H NMR