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Can. J. Chem. Vol. 78, 2000
(br.s, H-2 or H-3′, 1H), 5.73 (br.s, H-2 or H-3′), 3.67 (s,
COOMe, 3H), 3.60 (t, J = 6.6 Hz, 2H), 2.43 (d, J = 17.1 Hz,
H-5′, 1H), 2.32 (d, J = 17.1 Hz, H-5′, 1H), 1.99 (d, J =
1.1 Hz, 6-CH3, 3H), 1.90 (d, J = 1.3 Hz, 7′-CH3, 3H), 1.57–
1.19 (m, 10H), 0.94 (s, 9′-CH3). LRFABMS (m/z) (rel. int.):
365 [M+1]+ (100), 85 (93). HRFABMS (m/z) C21H32O5 re-
quires: 365.2328 [M+1]+; found: 365.2325 [M+1]+.
citric acid and extracted with EtOAc (3 × 20 mL). The or-
ganic extracts were combined, washed with brine, dried
(Na2SO4), and were concentrated to afford 100 mg (95%) of
3′-thiol ABA 12, which was used immediately in the next
step. IR νmax (cm–1): 3369, 2924, 1671, 1599, 1246. 1H
NMR δ: 7.77 (d, J = 16 Hz, 1H), 6.11 (d, J = 16 Hz, 1H),
5.74 (s, 1H), 4.67 (s, 1H), 2.55 (d, J = 17 Hz, 1H), 2.50 (d,
J = 17 Hz, 1H), 2.02 (s, 3H), 1.96 (s, 3H), 1.07 (s, 3H), 1.01
(s, 3H).
Hydroxy acid 9
A solution of ester 8 (100 mg, 0.274 mmol) in MeOH
(2 mL) and 10% KOH (2 mL) was stirred at 50°C for 1 h.
Water was added and the mixture was extracted with EtOAc
and discarded. The remaining aqueous layer was then acidi-
fied with 10% HCl to pH 3 and was extracted several times
with EtOAc. The organic layers were combined, washed
with water, brine, and were dried (Na2SO4). The solvent was
removed and the residue was purified by column chromatog-
raphy (50% acetone in hexane) to give 66 mg (69%) of the
A solution of the crude thiol ABA 12 (100 mg,
0.33 mmol) and (iodoacetamido)-fluorescein (200 mg,
0.40 mmol) in MeOH (30 mL) was treated with 1 M NaOH
(3 mL) at room temperature under nitrogen. After 2 days the
mixture was concentrated in vacuo, and the residue was dis-
solved in water (100 mL), acidified with 1 M HCl, and was
extracted with ethyl acetate (3 × 20 mL). The organic ex-
tracts were dried (Na2SO4), concentrated in vacuo, and the
residue chromatographed (toluene–EtOAc–HOAc, 50:30:2)
to afford 3′-S-acetamidofluorescein ABA 13 (113 mg, 50%)
as a yellow glass. IR νmax (cm–1): 3417, 2922, 1734, 1384,
1
acid 9. IR νmax (cm–1): 3308 (OH), 1704 (CO). H NMR δ:
7.77 (d, J = 16.1 Hz, H-4, 1H), 6.15 (d, J = 16.1 Hz, H-5,
1H), 5.96 (br.s, H-2 or H-3′, 1H), 5.75 (br.s, H-2 or H-3′),
3.60 (t, J = 6.5 Hz, 2H), 2.44 (d, J = 17.2 Hz, H-5′, 1H),
2.34 (d, J = 17.2 Hz, H-5′, 1H), 2.03 (d, J = 1.2 Hz, 6-CH3,
3H), 1.90 (d, J = 1.0 Hz, 7′-CH3, 3H), 1.58–1.17 (m, 10H),
0.96 (s, 9′-CH3). LRFABMS (m/z) (rel. int.): 351 [M+1]+
(100), 102 (64). HRFABMS (m/z) C20H30O5 requires:
351.2171 [M+1]+; found: 351.2150 [M+1]+.
1
1113. H NMR (CD3OD) δ: 7.93 (d, J = 8.5 Hz, 1H), 7.85
(dd, J = 8.5, 1.7 Hz, 1H), 7.54 (d, J = 16.3 Hz, 1H), 7.45 (d,
J = 1.7 Hz, 1H), 6.75 (m, 2H), 6.66 (m, 2H), 6.57 (m, 2H),
5.87 (d, J = 16.3 Hz, 1H), 4.89 (s, 1H), 3.57 (d, J = 14.4 Hz,
1H), 3.42 (d, J = 14.4 Hz, 1H), 2.48 (d, J = 16.6 Hz, 1H),
2.18 (d, J = 16.6 Hz, 1H), 2.17 (s, 3H), 1.76 (s, 3H), 0.95 (s,
3H), 0.93 (s, 3H). ESMS m/z: 301 (100), 684 [M+1]+ (10).
HREIMS (m/z) C37H34NO10S requires: 684.1903 [M+1]+;
found: 684.1885 [M+1]+.
Benzophenone coupling (10)
A solution of acid 9 (16.0 mg, 0.046 mmol), Et3N
(0.13 mL, 0.914 mmol), and 3′-O-(4-benzoyl)benzoyl imida-
zolide (22) (44.0 mg, 0.138 mmol) in CH2Cl2 (1 mL) was
stirred at room temperature overnight. The mixture was then
quenched with 5% HCl. The organic layer was then sepa-
rated, and washed with brine, was dried (Na2SO4) and was
concentrated. Purification of the residue by preparative thin
layer chromatography (5% MeOH in CH2Cl2) provided
9.6 mg (38%) of the 8′-benzophenone ABA derivative 10,
Preparation of the 3′-S-(2-ethyldansylamide) derivative
of ABA
5-(N,N-Dimethylamino)naphthalene-1-sulfon(2-
hydroxyethyl)amide
A solution of pyridine (3 mL) and ethanolamine (281 mg,
4.6 mmol) under N2 was treated with dansyl chloride
(500 mg, 1.9 mmol) and stirred for 17 h. Water (15 mL) was
added and stirring continued for a further 1 h followed by
extraction of the mixture with EtOAc (3 × 25 mL). The
combined organic extract was washed with brine (2 ×
75 mL), dried (Na2SO4), and concentrated in vacuo to afford
the dansyl ethanolamide as a light green oil (545 mg, 100%
based on dansyl chloride). The product was homogeneous
by TLC (toluene–EtOAc–HOAc, 25:15:2), Rf ca. 0.30 and
used without further purification. UV λ max (nm): 217, 250,
335. IR νmax (cm–1): 3509, 3301, 2944, 2871, 2788, 1575,
1
mp 141–143°C (hexane). H NMR δ: 8.12 (m, 2H), 7.80 (m,
5H), 7.60 (m, 1H), 7.48 (m, 2H), 6.16 (d, J = 16.0 Hz, H-5,
1H), 5.95 (br.s, H-2 or H-3′, 1H), 5.76 (br.s, H-2 or H-3′),
4.31 (t, J = 6.6 Hz, 2H), 2.44 (d, J = 17.3 Hz, H-5′, 1H),
2.34 (d, J = 17.3 Hz, H-5′, 1H), 2.03 (d, J = 0.9 Hz, 6-CH3,
3H), 1.90 (d, J = 1.0 Hz, 7′-CH3, 3H), 1.77–1.18 (m, 10H),
0.96 (s, 9′-CH3). LRFABMS (m/z) (rel. int.): 558 [M+1]+
(100), 102 (64). HRFABMS (m/z) C34H38O7 requires:
559.2696 [M+1]+; found: 559.2660 [M+1]+.
1
1456, 1312, 1143, 1060, 940, 790. H NMR (CDCl3) δ: 8.51
Preparation of the 3′-S-acetamidofluorescein derivative
of ABA (13)
(1H, d, J = 8.5 Hz), 8.24 (1H, d, J = 8.6 Hz), 8.21 (1H, d,
J = 7.2 Hz), 7.52 (1H, t, J = 8.0 Hz), 7.49 (1H, t, J =
7.8 Hz), 7.15 (1H, d, J = 7.5 Hz), 5.68 (1H, bs), 3.59 (2H, t,
J = 4.9 Hz), 3.00 (2H, t, J = 4.9 Hz), 2.86 (6H, s). MS (FIB)
(m/z) (rel. int.): 295 [MH]+ (100), 294 [M]+ (70), 252 (5),
218 (7), 184 (10), 170 (70), 157 (11), 128 (7), 88 (15).
HRMS (FIB) calcd. for C14H19N2O3S1 [MH]+: 295.1116;
found: 295.1113.
NaH (60% in oil, 20 mg, 0.5 mmol) was added to a solu-
tion of 2′,3′-epoxy ABA 11 (100 mg, 0.357 mmol, ref. (12))
in THF (6 mL) at 0°C under nitrogen. Thiol acetic acid (5
drops, ca. 55 mg, 0.7 mmol) and a further portion of sodium
hydride (60% in oil, 15 mg, 0.38 mmol) were then added
and the reaction mixture was allowed to warm to room tem-
perature. After stirring for an hour, a solution of 0.25 M
NaOH (15 mL) was added and stirring continued under ni-
trogen for another hour. The resultant mixture was concen-
trated in vacuo to ca. 10 mL, water (25 mL) was added, and
was washed with ether (2 × 15 mL). The ether washings
were discarded and the aqueous layer was acidified with 1 M
5-(N,N-Dimethylamino)naphthalene-1-sulfon(2-
mesyloxyethyl)amide
A solution of dansyl ethanolamide (320 mg, 1.1 mmol) in
pyridine (5 mL) was treated with methanesulfonyl chloride
© 2000 NRC Canada