was added. After refluxing for 2 h, it was cooled to
room temperature, and then water (50 mL) was
added. The aqueous layer was extracted with chloro-
form, and the combined organic layer was washed
with water, saturated NaHCO3 solution, and brine
successively and dried over anhydrous MgSO4. Fil-
tration and evaporation afforded crude dihalide 4,
which was used without purification. The crude can
be recrystallized from hexane to give the desired
The aqueous solution was extracted with ether
(3330 mL). The combined organic layer was washed
with brine and dried over anhydrous MgSO4. Filtra-
tion and evaporation gave a crude product, which
was purified by aluminum oxide (brockmann 3) col-
umn chromatography (hexane:EtOAc 6:1) to give a
mixture of the diastereomers 6 and recovered 5. The
two diastereomers 6 were dissolved in CHCl3 to
afford the desired diastereomers 7 (0.36 g, 53%
yield) and the diol, which was separated by chroma-
1
dihalide 4 (0.62 g, 88% yield). H-NMR: d 7.6-7.5 (m,
1
2H); 7.3-7.3 (m, 3H); 5.29 (s, 1H); 3.94 (d, J511.7
Hz, 1H); 3.62 (d, J511.4 Hz, 1H); 3.57 (d, J511.7
Hz, 1H); 3.56 (d, J511.1 Hz, 1H); 3.52 (dd, J511.7,
2.4 Hz, 1H); 3.43 (dd, J511.7, 2.4 Hz, 1H); 0.80 (s,
3H); 0.76 (s, 3H). 13C-NMR: d 136.4, 129.9, 128.6,
127.8, 97.9, 71.2, 71.0, 63.6, 29.7, 27.8, 22.3. MS:
tography (hexane:EtOAc 3:1). H-NMR: d 8.0-7.9 (m,
2H); 7.6-7.4 (m, 3H); 5.22 (d, J57. 2 Hz, 1H mi);
5.11 (d, J52.4 1H ma); 5.10 (s, 1H mi); 4.78 (d,
J56.6 Hz, 1H ma); 3.75 (ddd, J58.1, 7.2, 2.4 Hz, 1H
ma); 3.41 (m, 1H mi); 2.39 (m, 1H mi); 2.03 (dsept,
J5 8.1, 6.6 Hz, 1H ma); 1.31 (s, 9H ma); 1.26 (s, 9H
mi); 1.15 (d, J56.6 Hz, 3H); 1.09 (d, J56.6 Hz, 3H);
1.087 (d, J56.6 Hz, 3H); 1.03 (d, J56.6 Hz, 3H). 13C-
NMR: d 158.5, 157.6, 156.5, 156.0, 155.7, 154.7,
132.9, 132.8, 132.6, 122.9, 81.1 (mi), 80.8 (ma), 73.2
(mi), 71.4 (ma), 62.4 (mi), 61.3 (ma), 29.8 (ma, mi),
28.1, 28.0 (ma, mi), 20.1 (ma), 20.0 (ma), 19.7 (mi),
19.1 (mi). MS: m=z 332 (3), 276 (100), 232 (14).
HRMS: m=z for (MH1) C19H26NO4: calcd. 332.1862,
found 332.1834; for (MH1-C4H8) C15H18NO4: calcd.
m=z (M-Cl) 299 (5) 297 (5), 209 (90), 207 (90), 69
(100). HRMS: m=z for
calcd. 334.0290
C
13CH19O2BrCl (MH1):
12
13
found
334.0291;
for
12
C
13CH18O281Br (M-Cl): calcd. 300.0503 found
13
12
300.0408; for
C
13CH18O279Br (M-Cl): calcd.
13
298.0524 found 298.0442; for C14H18O279Br (M-Cl):
calcd. 297.0490 found 297.0468.
Phenyl cyclopropenone Acetal (5). To solution of
potassium tert-butoxide (0.59 g, 5.23 mmol) in THF
(5 mL) and HMPA (1.37 mL, 7.83 mmol) was added
via cannula dihalide 4 (0.87g, 2.61 mmol) in THF (5
mL). The reaction was carried under argon atmos-
phere. After stirring for 4 h at 0ꢀC the reaction was
allowed to warm up to room temperature and stirred
overnight. Then water (20 mL) was added, and the
aqueous solution was extracted with hexane (3 3 20
mL). The combined organic layer was washed with
brine and dried over anhydrous MgSO4. Filtration
and evaporation gave a crude product, which was
purified by deactivated (brockmann 3) aluminum ox-
ide chromatography (hexane: EtOAc 30:1) to afford
compound 5. (0.39 g, 60% yield). The CDCl3 for
NMR was passed through K2CO3 (Alternatively
276.1236,
found
276.1175;
for
(MH1)
12
C
13CH26NO4: calcd. 333.1895, found 333.1926;
18
for (MH1-C4H8)
C
13CH18NO4: calcd. 277.1269,
12
14
found 277.1219.
2-f(2S)-2-amino-1-hydroxy-3-methylbutylg-3-phe-
nylcyclopropenone hydrochloride (8). To solu-
tion of 7 (87 mg, 0.26 mmol) in 1,4-dioxane (0.25
mL) and water (5.6 mL) 4N HCl in 1,4-dioxane (0.8
mL) was added at room temperature. After stirring
for 30 min, the solution was evaporated in warm
bath to afford compound 8 as highly hygroscopic
salt. (54 mg, 90% yield). 1H-NMR: d 8.1-8.0 (m, 2H);
7.7-7.5 (m, 3H); 5.41 (d, J54.5 Hz, 1H mi); 5.19 (d,
J56.6 Hz, 1H ma); 3.42 (dd, J56.3, 5.4 Hz, 1H ma);
3.33 (dd, J59.6, 4.5 Hz, 1H mi); 2.28 (septd, J56.9,
5.4 Hz, 1H ma); 2.08 (dsept, J59.6, 6.9 Hz, 1H mi);
1.21 (d, J56.9 Hz, 1H mi); 1.19 (d, J56.9, 1H ma);
1.16 (d, J56.9 Hz, 1H mi); 1.158 (d, J56.9 Hz, 1H
ma). 13C-NMR: d 157.5, 157.1, 154.4, 134.8, 133.9,
130.5, 123.7, 68.6 (mi), 68.0 (ma); 62.6 (mi), 60.8
(ma), 30.1 (mi), 29.3 (ma), 19.9 (mi), 19.7 (ma), 17.4
(ma, mi). MS: m=z 232 (100), 214 (50).
1
CD3CN was used as solvent). H-NMR: d 7.68 (s, 1H);
7.64-7.61 (m, 2H); 7.50-7.35 (m, 3H); 3.74 (s, 4H); 1.14
(s, 3H); 1.06 (s, 3H). 13C-NMR: d 135.6, 130.1, 129.7,
128.9, 125.9, 114.7, 83.0, 77.8, 30.5, 22.6, 22.4. MS:
m=z 217 (M1, 100). HRMS: m=z for
(MH1): calcd. 218.1262 found 218.1251.
C
13
13CH17O2
12
2-f(2S)-2-Bocamine-1-hydroxy-3-methyl-butylg-3-
phenylcyclopeopenone (7). To solution of
a
5
(0.82 g, 3.8 mmol) and dry N,N,N’,N’-tetramethyle-
thylenediamine (1.14 mL, 7.8 mmol) in dry THF (8
mL), was added n-BuLi (1.2 M in THF, 3.16 mL) at -
78ꢀC over 5 min. After the mixture was stirred for
20 min, a solution of N-Boc-valinal14 (0.42 g, 2.11
mmol) in dry THF (4 mL) was added via cannula.
The mixture was stirred for 2 h at -78ꢀC. After addi-
tion of 1:4 water:THF (4 mL) the mixture was
diluted with ether and extracted with water (33).
2-f(2S)-2-(Cbz-Leucyl-amino)-1-hydroxyl-3-meth-
ylbutylg-3-phenyl-cyclopropenone (9). Cbz-Leu-
OH (77 mg, 0.29 mmol), PyBOP (154 mg, 0.29
mmol) and the hydrochloride salt 8 (60 mg, 0.26
mmol) were dissolved in CH2Cl2 (2 mL) and Et3N
(0.13 mL, 9.5 mmol) was added. After 15 min of stir-
ring at room temperature, the pH checked for basic
condition and the mixture was stirred for additional
2.5 h. It was then quenched with an aq KHSO4
Cohen et al.
PROTEIN SCIENCE VOL 22:788—799 797