4206 J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 21
Patel et al.
mL). The organic layer was dried over sodium sulfate, filtered,
and concentrated in vacuo. The residue was purified on Merck
silica gel (30 mL) and eluted with ethyl acetate/hexane (3:1 to
100:0) to give the coupled intermediate (113 mg, 20%): TLC
Rf ) 0.45 (EtOAc, visualized by ceric ammonium sulfate); MS
After the mixture was stirred for 3 h, additional p-toluene-
sulfonic acid monohydrate (42 mg, 0.214 mmol, 0.65 equiv)
was added. After the mixture was stirred an additional 4 h,
the solvents were removed in vacuo and the residue was
dissolved in ethyl acetate (40 mL) and washed sequentially
with 10% sodium bicarbonate (10 mL) and saturated sodium
chloride (10 mL). The organic solution was dried over sodium
sulfate, filtered, and concentrated in vacuo. The residue was
purified on Merck silica gel (30 mL), eluting with hexane/
acetone (2:1) to give 22 (110 mg, 50%): TLC Rf ) 0.48 (1:1
hexane/acetone visualized by ceric ammonium sulfate); MS (M
+ H)+ 667; HRMS (M + H)+ calculated 667.4104, found
667.4082 for C34H59O7N4S; 1H NMR (270 MHz, CDCl3/CD3OD,
10:1) δ 0.92 (m, 12 H), 1.59 (s, 6 H), 1.67 (s, 3 H), 1.68 (s, 3 H),
2.07 (s, 3 H), 1.90-2.22 (m, 12 H), 2.51 (br m, 2 H), 3.57 (br
m, 2 H), 3.73 (s, 3 H), 4.20-4.65 (m, 5 H), 5.10-5.27 (m, 3 H);
13C 68 MHZ (CDCl3:CD3OD 10:1) δ 15.2, 160, 16.4, 17.7, 18.4,
18.5, 19.1, 19.2, 25.7, 26.5, 26.8, 29.2, 30.0, 30.6, 31.1, 39.7,
45.8, 51.4, 51.5, 52.5, 53.8, 53.9, 58.8, 59.2, 117.4, 123.8, 124.4,
131.4, 135.4, 141.1, 168.7, 171.7, 172.3.
1
(M + H)+ 721; H NMR (400 MHz, CDCl3) δ 0.95 (m, 12 H),
1.60 (s, 6 H), 1.67 (s, 3 H), 1.70 (s, 3 H), 1.60-2.33 (m, 18 H),
3.55 (m, 3 H), 3.73 (s, 3 H), 3.97 (m, 2 H), 4.25-4.75 (m, 6 H),
4.91-5.27 (m, 4 H); 13C NMR (100 MHz, CDCl3) δ 16.0, 16.4,
17.6, 17.7, 19.4, 20.2, 21.3, 23.2, 24.7, 24.8, 25.7, 26.3, 26.4,
26.7, 29.1, 29.4, 29.5, 37.5, 39.5, 39.6, 39.7, 40.4, 46.0, 51.7,
52.4, 55.2, 55.3, 60.3, 60.4, 62.2, 62.6, 64.7, 67.9, 104.2, 117.5,
117.7, 117.8, 123.6, 123.7, 124.3, 131.3, 135.4, 140.5, 140.6,
140.8, 169.0, 160.2, 170.6, 171.3, 172.4, 172.5.
To a solution of of the above intermediate (113 mg, 0.157
mmol, 1 equiv) in THF (1 mL) at room temperature under N2
was added p-toluenesulfonic acid monohydrate (33 mg, 0.173
mmol, 1.1 equiv). After the mixture was stirred at room
temperature for 3 h, more p-toluenesulfonic acid monohydrate
(16 mg, 0.086 mmol, 0.55 equiv) was added. After the mixture
was stirred an additional 2 h, the solvents were removed in
vacuo, and the residue was dissolved in ethyl acetate (20 mL)
and washed sequentially with saturated sodium bicarbonate
(10 mL) and saturated sodium chloride (10 mL). The organic
solution was dried over sodium sulfate, filtered, and concen-
trated in vacuo. The residue was purified on Merck silica gel
(14 mL), eluting with hexane/acetone (4:1 to 1:4) to give 19
(54 mg, 54%): TLC Rf ) 0.40 (EtOAc, visualized by ceric
P r ep a r a tion of 23. To a solution of 22 (110 mg, 0.165
mmol, 1 equiv) in dioxane/methanol/water (3.5 mL, 4:2:1) was
added 1 N NaOH (231 µL, 0.231 mmol, 1.4 equiv). After the
mixture was stirred for 6 h, the solvents were removed in
vacuo. The residue was purified on CHP-20P (15 mL), eluting
with water/acetonitrile (0:100 to 100:0) to give 23 after
lyophilization (63 mg, 57%): mp 135-139 °C; TLC Rf ) 0.67
(CHCl3/CH3OH/HOAc, 5:1:0.05, visualized by ceric ammonium
1
1
ammonium sulfate); H NMR (270 MHz, CDCl3) δ 0.80-1.05
sulfate); MS (M + H)+ 653; [R]D ) -27.8° (c ) 0.78, H2O); H
(m, 12 H), 1.60 (s, 6 H), 1.67 (s, 3 H), 1.69 (s, 3 H), 1.60-2.30
(m, 12 H), 3.72 (s, 3 H), 3.5-4.5 (m, 9 H), 5.02-5.3 (m, 3 H),
7.60-8.00 (m, 3 H); 13C NMR (68 MHz, CDCl3) δ 16.0, 16.4,
17.6, 17.7, 19.3, 21.1, 23.2, 24.8, 25.7, 26.4, 26.8, 29.3, 39.7,
40.1, 41.1, 41.3, 46.0, 52.0, 52.5, 53.9, 55.1, 60.9, 62.4, 69.6,
117.2, 123.7, 124.3, 131.3, 135.4, 141..3, 168.1, 170.5, 170.8,
171.1, 171.9, 173,2
NMR (400 MHz (CD3OD) δ 0.96 (m, 12 H), 1.60 (s, 6 H), 1.66
(s, 3 H), 1.71 (s, 3 H), 2.05 (s, 3 H), 1.88-2.21 (m, 12 H), 2.50
(m, 2 H), 4.18-4.30 (m, 5 H), 5.10-5.32 (m, 3 H); 13C NMR
(68 MHz, CD3OD) δ 15.3, 16.1, 16.5, 17..8, 18.3, 18.9, 19.9,
25.9, 27.4, 27.8, 31.1, 31.6, 24.1, 40.7, 40.8, 47.2, 48.0, 48.4,
48.6, 55.7, 60.3, 60.7, 119.3, 125.1, 125.4, 136.2, 141.4, 172.6,
173.8, 177.7. HRMS (M + Na)+ calculated 675.3767, found
675.3759. Anal. (C33H53N4O7SNa‚2.65H2O) C, H, N.
P r ep a r a tion of HCl‚H-Va l-Va l-(D-Met)-OMe (24): HCl‚
H-(D-Met)-OMe. To a suspension of D-methionine (5g, 0.335
mmol, 1 equiv) in 2,2-dimethoxypropane (330 mL) was added
11.7 M hydrochloric acid (33 mL). After the mixture was
stirred for 16 h, the solvents were removed in vacuo. The
residue was dissolved in methanol (50 mL) and diluted with
ether (400 mL), and the resulting precipitate was filtered and
washed with ether (50 mL). The precipitate was redissolved
in methanol (30 mL) and slowly precipitated with ether (200
mL). The precipitate was filtered, washed with ether (40 mL),
and dried in vacuo to give the HCl salt of H-(D-Met)-OMe (5.44
g, 84%): mp 147-148 °C; TLC Rf ) 0.48 (9:1:0.05 chloroform/
methanol/acetic acid visualized by ceric ammonium sulfate);
IR (KBr) 1748 cm-1; MS (M + H)+ 164; [R]D ) -23.58° (c )
0.85, CH3OH); 1H NMR (270 MHz, CD3OD) δ 2.21 (s, 3 H),
2.31 (m, 2 H), 2.76 (t, 2 H, J ) 7.03), 3.95 (s, 3 H), 4.32 (t, 1 H,
J ) 6.45); 13C NMR (68 MHz, CD3OD) δ 14.9, 30.0, 30.7, 52.7,
53.7, 170.7.
P r ep a r a tion of 20. To a solution of 19 (54 mg, 0.085 mmol,
1 equiv) in 2:1 methanol/water (1 mL) at 0 °C was added 1 N
sodium hydroxide (125 µL, 0.125 mmol, 1.4 equiv). After the
mixture was stirred for 1 h, TLC indicated completion of the
reaction. The solvents were removed, and the residue was
purified on CHP-20P (10 mL) eluting with acetonitrile/water
(1:9 to 8:2). Appropriate fractions were combined and lyo-
philized to give 20 (39 mg, 66%): mp 136-139 °C; TLC Rf )
0.15 (9:1:0.05 CHCl3/CH3OH/HOAc visualized by ceric am-
monium sulfate); MS (M + H)+ 623; [R]D ) -19.6° (c ) 1.0,
1
H2O); H NMR (400 MHz, D2O) δ 0.90-1.11 (m, 12 H), 1.58
(s, 6 H), 1.65 (s, 3 H), 1.71 (s, 3 H), 1.58-1.71 (m, 3 H), 1.96-
2.04 (m, 9 H), 3.87-4.51 (m, 9 H), 5.09-5.32 (m, 3 H); 13C NMR
(68 MHz, D2O) δ 1.6.7, 17.2, 18.2, 18.4, 19.8, 21.7, 23.9, 26.4,
27.5, 27.7, 30.3, 40.7, 47.2, 52.3, 58.2, 60.7, 62.4, 117.2, 125.2,
125.5, 131.3, 135.4, 141.3, 168.1, 170.5, 175.1, 176.2. HRMS
(M + Na)+ calculated 645.3839, found 645.3841. Anal.
(C32H53N4O8Na‚0.75H2O) C, H, N.
P r ep a r a tion of 22. To a solution of 18 (415 mg, 1.02 mmol,
1.0 equiv) in dimethylformamide (12 mL) was added H-VVM-
OCH3 21 (368 mg, 1.02 mmol, 1.0 equiv), BOP (451 mg, 1.02
mmol, 1.0 equiv), and iPr2NEt (522 µL, 3.06 mmol, 3.0 equiv).
After the reaction mixture was stirred for 20 h at room
temperature, it was concentrated in vacuo. The residue was
purified on Merck silica gel (100 mL), eluting with hexane/
ethyl acetate (1:1 to 1:2) to give the coupled product (247 mg,
32%): TLC Rf ) 0.62 (ethyl acetate, visualized by ceric
ammonium sulfate); MS (M + H)+ 751; HRMS (M + H)+
calculated 751.4679, found 751.4614 for C39H67O8N4S; 1H NMR
(400 MHz, CDCl3) δ 0.95 (m, 12 H), 1.59 (s, 6 H), 1.67 (s, 6 H),
2.0 (s, 3 H), 1.60-2.25 (m, 18 H), 2.48 (m, 2 H), 3.72 (s, 3 H),
3.42-4.00 (m, 4 H), 4.22-4.71 (m, 5 H), 4.97-5.29 (m, 4 H),
7.53 (br m, 3 H); 13C NMR (100 MHz, CDCl3) δ 15.3, 16.0, 16.4,
17.7, 18.2, 19.2, 19.4, 199, 24.9, 25.7, 26.4, 26.7, 30.1, 30.4,
30.5, 30,8, 31.2, 39.6, 39.7, 40.2, 46.2, 51.5, 52.3, 58.6, 59.0,
64.1, 104.5, 118.3, 118.4, 123.8, 124.3, 131.2, 135.3, 139.8,
140.0, 167.3, 170.1, 171.4, 172.2.
Boc-Va l-(D-Met)-OMe. To a suspension of D-methionine
methyl ester (5 g, 25 mmol, 1 equiv), Boc-valine (5.51 g, 25
mmol, 1 equiv), and HOBT (3.88 g, 25 mmol, 1 equiv) in THF/
DMF (160 mL, 3:1) was added iPr2NEt (4.85 mL, 28 mmol,
1.1 equiv). The suspension was cooled to 0 °C, and EDC (4.87
g, 25 mmol, 1 equiv) was added. The ice bath was removed,
and after being stirred for 1 h, the reaction mixture was a clear
solution. The solution was stirred for 16 h, and the reaction
mixture was concentrated to ∼40 mL. The concentrate was
diluted with ethyl acetate (200 mL) and washed with saturated
sodium bicarbonate (100 mL), phosphate buffer (pH ) 4, 100
mL), and 10% lithium chloride (3 × 100 mL), dried over sodium
sulfate, filtered, and concentrated in vacuo. The residue was
triturated with petroleum ether (50 mL) to give Boc-Val-(D-
Met)-OMe (7.72 g, 84%): mp 94-95 °C; TLC Rf ) 0.91 (4:1:1
butanol/acetic acid/water visualized by ceric ammonium sul-
1
fate); IR (KBr) 1750 cm-1; MS (M + H)+ 363; H NMR (400
MHz (CDCl3) δ 0.91 (d, 3 H, J ) 6.84), 0.98 (d, 3 H, J ) 6.84),
1.45 (s, 9 H), 2.01 (m, 1 H, J ) 7.26), 2.09 (s, 3 H), 2.82 (m, 2
H), 2.49 (t, 2 H, J ) 7.26), 3.75 (s, 3 H), 4.0 (m, 1 H), 4.71 (dd,
1 H, J ) 7.26), 5.0 (m, 1 H), 6.81 (d, 1 H, J ) 7.69); 13C NMR
To a solution of above intermediate (247 mg, 0.329 mmol, 1
equiv) in tetrahydrofuran (2 mL) was added p-toluenesulfonic
acid monohydrate (81 mg, 0.428 mmol 1.3 equiv) under N2.