to 0 °C before addition of boron trifluoride etherate (630 µL, 5
mmol). After 4 h of stirring at rt, the reaction was quenched by
adding 50 mL of saturated bicarbonate solution. The aqueous layer
was extracted with CH2Cl2 (2 × 100 mL), and the organic layers
were combined, dried over Na2SO4, and evaporated to dryness. The
crude product was then purified by silica gel column chromatog-
raphy (0-30% AcOEt in cyclohexane) to afford 3 (104 mg, 21%)
Synthesis of Solid-Supported Phosphotriester Alkyne Scaf-
folds. The solid-supported phosphotriester alkyne scaffolds were
synthesized on a DNA synthesizer (ABI 394) using standard
phosphoramidite chemistry on the monoalkyne solid support 7 using
alkyne phosphoramidite 6 (0.09 M in anhydrous CH3CN) or
commercially available thymidine phosphoramidite (0.075 M in
anhydrous CH3CN) and benzylmercaptotetrazole (0.3 M in anhy-
drous CH3CN) as activator.
1
as a colorless oil. Rf ) 0.29 (AcOEt/cyclo, 1:1, v/v). H NMR
(CDCl3, 200 MHz): δ 0.85-2.08 (m, 22H), 3.05-3.35 (m, 3H),
3.65-3.86 (m, 2H), 4.00-4.17 (m, 2H), 4.34-4.39 (m, 1H), 4.94
(dd, 1H, J ) 3.2 Hz, J ) 10.5 Hz), 5.14 (dd, 1H, J ) 7.8 Hz, J )
10.5 Hz), 5.32 (d, 1H, J ) 3.2 Hz). 13C NMR (CDCl3, 300 MHz):
δ 19.9, 20.0, 20.3, 24.3, 24.4, 25.3, 25.5, 28.0, 28.2, 29.1, 29.2,
34.2, 34.8, 37.0, 37.4, 54.7, 57.1, 60.5, 66.3, 68.2, 69.9, 70.2, 72.3,
74.8, 100.9, 168.7, 169.5, 169.6,169.7. ESIMS+: m/z 500.3 (M +
H)+, 331.1 (M + H - (HO-DMCH-N3))+, 271.1 (M + H - (HO-
DMCH-N3) - CH3CO2H)+, 211.1 (M + H - (HO-DMCH-N3) -
2CH3CO2H)+, 169.1 (M + H - C14H19O9)+. HRMS ESI+: m/z
calcd for C22H34N3O10 (M + H)+ 500.2244, found 500.2244.
1-O-(3-Azidopropyl)-2,3,4,6-tetra-O-acetyl-ꢀ-D-galactopyrano-
side (4). Synthesized according ref 11.
General Procedure for Cu(I)-Catalyzed 1,3-Dipolar Cycload-
dition. To a solid-supported oligoalkyne phosphotriester 8a-c (0.3
µmol) was added a mixture of 1-O-(3-azidopropyl)-2,3,4,6-tetra-
O-acetyl-ꢀ-D-galactopyranoside 4 (1.5 equiv by alkyne, 0.1 M
solution in MeOH) and 1-O-[[4-(azidomethyl)cyclohexyl]methyl]-
2,3,4,6-tetra-O-acetyl-ꢀ-D-galactopyranoside 3 (1.5 equiv by alkyne,
0.1 M solution in MeOH), and CuSO4 (0.4 equiv, 0.12 µmol, 3 µL
of a 40 mM solution in H2O), freshly prepared sodium ascorbate
(2 equiv, 0.6 µmol, 12 µL of a 50 mM solution in H2O), water,
and MeOH were added to obtain a total volume of 200 µL (1:1,
v/v). The other compounds with different ratios of carbohydrates
(1:2, 2:1) were prepared similarly. The resulting preparation was
treated in a sealed tube with microwave synthesizer Initiator from
Biotage set at 100 W with a 30 s premixing time. The temperature
was monitored with an internal infrared probe to 60 °C during 45
min. The solution was removed, and the CPG beads were washed
with H2O (2 mL) and MeOH (2 mL) and then dried.
1-O-(4,4′-Dimethoxytrityl)-2-propargyloxymethyl-2-meth-
yl-3-{O-[(2-cyanoethyl)-N,N-diisopropylphosphoramidite]-
1,3-propanediol (6). 1-Propargyl-2-[(4,4′-dimethoxytrityl)oxy-
methyl]-2-methylpropane-1,3-diol 513 (325 mg, 0.7 mmol) and
diisopropylammonium tetrazolide (60 mg, 0.35 mmol) were dried
three times by coevaporation with anhydrous acetonitrile and
then dissolved in anhydrous CH2Cl2 (5 mL) before addition of
2-cyanoethyl tetraisopropyl phosphorodiamidite (258 µL, 0.84
mmol) at rt. The resulting mixture was stirred at room temper-
ature for 3 h and then diluted with EtOAc (25 mL). The organic
layer was washed with brine (2 × 50 mL), dried (Na2SO4),
filtered, and evaporated. The residue was purified by chroma-
tography on silica gel (Cyclohexane/CH2Cl2 100/0 to 80/20 with
4% Et3N) affording the phosphoramidite 6 (422 mg 92%) as an
General Procedure for Deprotection. Beads were treated with
concentrated aqueous ammonia (500 µL) for 2 h at room temper-
ature, and the supernatant was withdrawn and evaporated to dryness.
The residue was dissolved in water for subsequent analyses.
Acknowledgment. We thank the Universite´ Montpellier 2
and CNRS: “Programme interdisciplinaire Interface Physique
chimie Biologie” for financial support. G.P. thanks the CNRS
and “Re´gion Languedoc Roussillon” for the award of a research
studentship. F.M. is from Inserm.
1
oil. Rf (cyclohexane/CH2Cl2/Et3N 7:2:1 v/v/v) ) 0.5. H NMR
(CDCl3, 200 MHz): δ 1.00-1.21 (m, 15H), 2.42 (bs, 1H),
2.53-259 (t, 2H, J ) 6.5 Hz), 3.03 (s, 2H), 3.43-3.79 (m, 8H),
3.82 (s, 6H), 4.11-4.18 (bs, 2H), 6.83-7.49 (m, 13H). 13C NMR
(CDCl3, 100 MHz): δ 17.8, 20.3, 24.5, 24.6, 41.2, 41.3, 43.2, 43.3,
53.3, 55.2, 58.3, 58.5, 58.6, 58.7, 65.2, 66,5, 66.6, 66.7, 72.8, 72.9,
73.9, 80.2, 85.7, 113.0, 117.4, 126.5, 127.6, 128.4, 130.2, 136.5, 145.3,
158.5. 31P NMR (CDCN3, 80 MHz): δ 148.6, 148.7. HRFABMS
(positive mode, nitrobenzylic alcohol): m/z calcd for C38H50N2O6P1
[M + H]+ 661.3407, found 661.3383.
1
Supporting Information Available: H and 13C and 31P
NMR spectra of new compounds. HPLC and MALDI-TOF
spectra of 9a-c with click performed in the presence of 1:2
and 2:1 molar ratio of 4:3. This material is available free of
JO8009837
J. Org. Chem. Vol. 73, No. 15, 2008 6017