Z. Liu, L. M. Sayre / Tetrahedron 60 (2004) 1601–1610
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eluting with ethyl acetate–hexane (v/v, 4:5) to give 1a and
5a as yellow oils in yields of 72.3 and 11.3%, respectively.
1a: 1H NMR (CDCl3, free base) d 2.30 (s, 6H), 3.83 (s, 2H),
7.87 (d, 1H, J¼11.0 Hz), 9.73 (d, 1H, J¼6.7 Hz); 13C NMR
(CDCl3) d 45.7 (2), 60.0 (þ), 120.8 (þ, d, J¼19.3 Hz),
123.7 (2, d, J¼1.2 Hz), 144.0 (þ), 145.6 (þ, d, J¼7.6 Hz),
154.5 (þ, d, J¼19.6 Hz), 157.5 (þ, d, J¼216.8 Hz); EI
HRMS m/z calcd for C9H10FN3O4 Mþ 243.0655, found
243.0649. The HCl salt of 1a was prepared by passing HCl
diluted to 4 mL with water and extracted with ether
(3£2 mL). The aqueous layer was acidified to pH 2 with
2 N HCl and extracted with ethyl acetate (3£2 mL). The
organic layer was dried over anhydrous Na2SO4 and the
solvent was evaporated to give 7d as a yellow powder in a
yield of 91.8%: mp .240 8C (dec); 1H NMR (methanol-d4)
d 0.92 (d, 6H, J¼5.9 Hz), 1.53–1.69 (3H), 4.22 (s, 2H), 4.37
(td, 1H, J¼3.3, 10.0 Hz), 7.02 (d, 1H, J¼9.6 Hz), 8.28 (dd,
1H, J¼2.7, 9.6 Hz), 9.04 (d, 1H, J¼2.6 Hz); 13C NMR
(methanol-d4) d 22.0 (2), 23.8 (2), 26.3 (2), 43.1 (þ), 46.9
(þ), 55.0 (2), 116.3 (2), 124.5 (2), 131.0 (2), 132.2 (þ),
137.5 (þ), 149.3 (þ), 164.3 (þ), 169.4 (þ); FAB HRMS m/
z calcd for C14H19N4O7 (MþH)þ 355.1254 found 355.1263.
1
gas through a solution of 1a in ether: mp 152–154 8C; H
NMR (methanol-d4) d 3.09 (s, 6H), 4.80 (s, 2H), 8.13 (d, 1H,
J¼10.6 Hz), 9.08 (d, 1H, J¼6.9 Hz); 13C NMR (methanol-
d4) d 44.6 (2), 58.9 (þ), 126.2 (2), 126.7 (2, d,
J¼24.4 Hz), 134.4 (þ, d, J¼10.1 Hz), 139.3 (þ, d,
J¼9.2 Hz), 146.0 (þ, d, J¼5.8 Hz), 158.7 (þ, d,
4.3.9. N a-Acetyl-S-(2,4-dinitro-5-(dimethylamino-
methyl)phenyl)-L-cysteine (11). According to the pro-
cedure for synthesis of 7b, 11 was obtained from N a-acetyl-
1
J¼221.0 Hz). 5a: H NMR (CDCl3) 2.16 (s, 6H), 3.71 (s,
2H), 7.34 (t, J¼8.2, 9.0 Hz) 7.90 (dd, J¼9.0, 4.6 Hz); 13C
NMR (CDCl3) d 45.2 (2), 54.9 (þ), 116.7 (d, J¼21.0 Hz),
127.4 (2, d, J¼9.0 Hz), 131.1 (þ), 140.5 (þ, d, J¼8.3 Hz),
146.6 (þ, d, J¼2.7 Hz), 155.0 (þ, d, J¼263.4 Hz); EI
HRMS m/z calcd for C9H10FN3O4 Mþ 243.0655, found
243.0649. According to the procedure for synthesis of 1a,
the 1:1 mixture of 1a and N,N-dimethyl-d6-2,4-dinitro-5-
fluorobenzylamine (1b) was prepared using a 1:1 mixture of
4a and 4b in a yield of 70.8%.
1
L-cysteine as a yellow powder in 100% yield: H NMR
(methanol-d4) d 2.00 (s, 3H), 2.97 (s, 6H), 3.50 (dd, 1H,
J¼14.1, 6.6 Hz), 3.65 (dd, 1H, J¼14.2, 6.3 Hz), 4.52 (t, 1H,
J¼6.5 Hz), 4.63 (s, 2H), 8.29 (s, 1H), 9.00 (s, 1H); 13C
NMR (methanol-d4) d 22.7 (2), 35.4 (þ), 44.7 (2), 53.4
(2), 59.3 (þ), 125.0 (2), 131.9 (þ), 134.2 (2), 145.9 (þ),
146.7 (þ), 147.1 (þ), 173.3 (þ), 175.0 (þ); FAB HRMS
m/z calcd for C14H19N4O7S (MþH)þ 387.0974, found
387.0975.
4.3.6. N a-(2,4-Dinitro-5-(dimethylaminomethyl)-
phenyl)glycyl-L-leucine (7b). A solution of 1a (100 mg)
in DMF (2 mL) was added to a suspension of glycyl-L-
leucine (50 mg, 0.266 mmol) and sodium bicarbonate
(100 mg) in water (1 mL) and the mixture was stirred at
room temperature for 1 h. The solution was diluted with
water (10 mL) and extracted with ethyl acetate (2£10 mL).
Water was evaporated to give a crude product, which was
subjected to preparative TLC eluted with methanol–ethyl
acetate (1:1, v/v) to give 7b as a yellow powder in a yield of
4.3.10. N a-Acetyl-O-(2,4-dinitro-5-(dimethylamino-
methyl)phenyl)-L-tyrosine (13). According to the pro-
cedure for the synthesis of 7b, 13 was obtained from N a-
1
acetyl-L-tyrosine as a yellow powder in 89.3% yield: H
NMR (HCl salt in methanol-d4) d 1.92 (s, 3H), 2.70 (s, 6H),
2.96 (dd, 1H, J¼14.1, 5.7 Hz), 3.21 (dd, 1H, J¼13.8,
5.0 Hz), 4.35 (s, 2H), 4.58 (m, 1H), 7.14 (d, 2H, J¼8.4 Hz),
7.38 (d, 2H, J¼8.4 Hz), 7.89 (s, 1H), 8.87 (s, 1H); 13C NMR
(HCl salt in methanol-d4) d 22.7 (2), 38.5 (þ), 44.7 (2),
55.4 (2), 69.7 (þ), 121.4 (2), 124.2 (2), 125.5 (2), 132.8
(2), 135.9 (þ), 137.7 (þ), 141.0 (þ), 143.6 (þ), 154.2 (þ),
156.2 (þ), 172.9 (þ), 175.3 (þ); FAB HRMS m/z calcd for
C20H23N4O8 (MþH)þ 447.1516, found 447.1513.
1
95.4%: mp .215 8C (dec); H NMR (methanol-d4) d 0.91
(d, 6H, J¼5.9 Hz), 1.60–1.71 (3H), 2.30 (s, 6H), 3.85 (s,
2H), 4.24 (s, 2H), 4.39 (m, 1H) 7.11(s, 1H), 8.95 (s, 1H); 13C
NMR (methanol-d4) d 22.2 (þ), 23.8 (þ), 26.3 (þ), 43.3
(þ), 46.0 (2), 46.9 (þ), 55.0 (2), 62.0 (þ), 117.6 (þ),
126.6 (þ), 131.1 (2), 138.1 (2), 143.7 (2), 148.0 (2),
169.5 (2), 179.8 (2); FAB HRMS m/z calcd for
C17H26N5O7 (MþH)þ 412.1832 found 412.1840.
4.3.7. N a-(2,4-Dinitro-5-(dimethylaminomethyl)-
phenyl)-L-asparagine (7a). According to the procedure
for the synthesis of 7b, 7a was obtained from L-asparagine
as a yellow powder in a yield of 85%: mp .200 8C (dec); 1H
NMR (methanol-d4) d 2.25 (s, 1H), 2.78 (dd, 1H, J¼13.9,
6.8 Hz), 2.87 (dd, 1H, J¼13.9, 4.6 Hz), 3.81 (s, 2H), 4.53 (t,
1H), 7.17 (s, 1H), 8.94 (s, 1H); 13C NMR (methanol-d4) d
39.5 (2), 46.0 (2), 57.1 (2), 60.2 (þ), 116.2 (2), 125.3
(2), 131.1 (þ), 137.3 (þ), 143.3 (þ), 148.1 (þ), 173.2 (þ),
175.8 (þ); FAB HRMS m/z calcd for C13H18N5O7 (MþH)þ
356.1206, found 356.1212.
4.3.11. N,N-Dimethyl-2,4-dinitro-5-((2-hydroxy-
ethyl)thio)benzylamine (14). According to the procedure
for the synthesis of 7b, 14 was obtained from mercapto-
ethanol as a yellow resin in 100% yield: 1H NMR (CDCl3) d
2.31 (s, 6H), 2.51 (b, 1H), 3.31 (t, 2H, J¼6.18 Hz), 3.87 (s,
2H), 3.99 (t, 2H, J¼6.24 Hz), 7.97 (s, 1H), 8.85 (s, 1H); 13C
NMR (CDCl3) d 35.11 (þ), 45.78 (2), 59.93 (þ), 60.16
(þ), 123.26 (2), 128.16 (2), 140.25 (þ), 143.72 (þ),
144.35 (þ); EI HRMS m/z calcd for C11H15N3O5S Mþ
301.0732, found 301.0726.
4.3.12. 2-Amino-6-(7-(5-amino-5-carboxypentylamino-
carbonyl)heptanoylamino)hexanoic acid (17). Disuccini-
midyl suberate (DSS) (50 mg, 0.135 mmol) and N a-Cbz-
lysine (151.2 mg, 0.54 mmol) were suspended in DMF
(5 mL) and the mixture was stirred at room temperature for
1 h. The reaction mixture was subjected to flash chroma-
tography eluted first with acetone, then with a mixture of
acetone and acetic acid (v/v 95:5). The solvent was
evaporated and the residue was dissolved in water
(20 mL). The aqueous solution was extracted with ethyl
acetate (3£10 mL). The combined organic layer was dried
4.3.8. N a-(2,4-Dinitrophenyl)glycyl-L-leucine (7d). A
solution of DNFB (19 mL, 0.15 mmol) in ethanol (0.8 mL)
was added to a suspension of glycyl-L-leucine (18.8 mg,
0.1 mmol) and sodium bicarbonate (33.6 mg) in water
(0.4 mL) and the mixture was stirred at room temperature
for 2 h. Ethanol was evaporated and the aqueous residue was