10.1002/chem.201903531
Chemistry - A European Journal
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Hz, 1H), 3.15 (dd, J = 5.2, 14.0 Hz, 1H), 3.00 (dd, J = 6.4, 14.0 Hz, 1H);
13C NMR (CDCl3, 125 MHz) δ 174.5, 170.3, 156.3, 137.2, 136.0, 135.7,
129.4, 128.7, 128.6, 128.6, 128.4, 128.2, 128.1, 128.0, 127.2, 73.6, 69.6,
67.4, 54.2, 53.5, 37.4; IR (ATR): 3279, 3059, 1724, 1696, 1656, 1537,
Purification method: The crude product was purified by GPC. HPLC
conditions: DAICEL CHIRALPAK ID 4.6 mm×25 cm, 10% IPA (containing
0.1% formic acid) in hexane (containing 0.1% formic acid), 40 °C, flow rate
1 mL/min, detection wavelength 254 nm, retention time 22.30 min (epimer
28.68 min). 165 mg, 0.242 mmol, 60% (epimer: 0.4%). White solid; 1H
NMR (CDCl3, 400 MHz) δ 10.0 (brs, 1H), 7.41-7.35 (m, 6H), 7.27-7.14 (m,
13H), 7.12-7.08 (m, 1H), 6.83-6.70 (m, 2H), 5.22 (s, 1H), 4.70 (s, 1H), 4.14-
3.95 (m, 2H), 3.22-3.09 (m, 1H), 3.02 (dd, J = 6.6, 13.9 Hz, 1H), 2.76 (dd,
J = 6.5, 12.4 Hz, 1H), 2.51 (s, 1H), 1.37 (s, 9H), 1.18 (d, J = 6.9 Hz, 3H);
13C NMR (CDCl3, 125 MHz) δ 173.4, 173.1, 169.9, 155.6, 144.4, 136.1,
129.6, 129.4, 128.5, 128.1, 128.0, 126.9, 80.5, 67.3, 53.6, 52.4, 50.2, 37.2,
33.1, 28.4, 18.4; IR (neat): 3310, 3030, 2931, 1715, 1682, 1506, 1445,
1367, 1249, 1166, 741, 701 cm-1; [α]30D = +4.82 (c 1.05, CH2Cl2); mp 114-
116 °C; HRMS (ESI-TOF): calcd for [C39H43N3O6S-H]- 680.2800, found
680.2801.
1496, 1238, 1043, 694 cm-1; [α]30 = +48.2 (c 1.01, CH2Cl2) ; mp 119-
D
121 °C; HRMS (ESI-TOF): calcd for [C27H28N2O6-H]- 475.1875, found
475.1876.
Boc-L-Tyr(O-Bn)-L-Phe-OH (4j)
Purification method: The crude product was purified by GPC. HPLC
conditions: DAICEL CHIRALPAK IB 4.6 mm×25 cm, 5% IPA (containing
0.1% formic acid) in hexane (containing 0.1% formic acid), 40 °C, flow rate
1 mL/min, detection wavelength 254 nm, retention time 10.74 min (epimer
15.40 min). 172 mg, 0.332 mmol, 83% (epimer: <0.1%). White solid; 1H
NMR (CDCl3, 400 MHz) δ 9.40 (brs, 1H), 7.34-7.03 (m, 9H), 7.03-6.90 (m,
4H), 6.85-6.67 (m, 3H), 5.25 (s, 1H), 4.86 (s, 2H), 4.69 (s, 1H), 4.33 (s,
1H), 3.04 (dd, J = 4.8, 13.6 Hz, 1H), 2.95-2.68 (m, 3H), 1.28 (s, 9H); 13C
NMR (CDCl3, 100 MHz) δ 173.8, 171.7, 157.9, 155.8, 137.1, 136.0, 130.5,
129.5, 128.8, 128.6, 128.5, 127.9, 127.4, 127.1, 115.0, 80.5, 70.0, 58.2,
55.7, 53.4, 37.6, 28.3; IR (neat): 3332, 2978, 2930, 1723, 1512, 1367,
1242, 1175, 1024, 861, 737, 699 cm-1; [α]30D = +27.4 (c 1.12, CH2Cl2); mp
121-123 °C; HRMS (ESI-TOF): calcd for [C30H34N2O6-H]- 517.2344, found
517.2344.
Boc-L-Ala-L-Phg-L-Phe-OH (4m)
THF was used for solvent instead of MeCN. Purification method: The crude
product was purified by column chromatography on silica gel (MeOH :
CHCl3 = 1 : 99 to 3 : 97). HPLC conditions: DAICEL CHIRALPAK IB 4.6
mm×25 cm, 8% IPA (containing 0.1% formic acid) in hexane (containing
0.1% formic acid), 40 °C, flow rate 1 mL/min, detection wavelength 254
nm, retention time 13.01 min (epimer 20.28 min). 128 mg, 0.272 mmol,
1
68% (epimer <0.1%). White solid; H NMR (CDCl3+CD3OD, 400 MHz) δ
7.26-7.02 (m, 10H), 5.38 (s, 1H), 4.59 (t, J = 6.4 Hz, 1H) 4.06 (d, J = 5.7
Hz, 1H), 3.11 (dd, J = 5.2, 13.9 Hz, 1H), 2.93 (dd, J = 7.5, 13.8 Hz, 1H),
1.32 (s, 9H), 1.20 (d, J = 7.1 Hz, 3H); 13C NMR (CDCl3+CD3OD, 125 MHz)
δ 173.1, 172.5, 169.8, 155.8, 136.4, 136.1, 128.8, 128.2, 127.9, 127.7,
126.7, 126.3, 79.5, 56.6, 53.4, 49.6, 36.8, 27.5, 17.1; IR (neat): 3307, 2978,
Fmoc-L-Cys(Trt)-L-Phe-OH (4j)
Purification method: The crude product was purified by GPC. HPLC
conditions: DAICEL CHIRALPAK IB 4.6 mm×25 cm, 8% IPA (containing
0.1% formic acid) in hexane (containing 0.1% formic acid), 40 °C, flow rate
1 mL/min, detection wavelength 254 nm, retention time 24.50 min (epimer
21.53 min). 239 mg, 0.326 mmol, 82% (epimer: <0.1%). White solid; 1H
NMR (CDCl3, 500 MHz) δ 8.55 (brs, 1H), 7.77-7.65 (m, 2H), 7.52 (s, 1H),
7.40-7.30 (m, 8H), 7.26-7.11 (m, 12H), 7.10-7.00 (m, 5H), 6.51 (d, J = 7.7
Hz, 1H), 5.20 (d, J = 7.9 Hz, 1H), 4.73 (q, J = 6.2 Hz, 1H), 4.36 (t, J = 6.8
Hz, 1H), 4.27 (t, J = 7.1 Hz, 1H), 4.13 (t, J = 7.0 Hz, 1H), 3.72 (d, J = 6.0
Hz, 1H), 3.11 (dd, J = 5.1, 13.9 Hz, 1H), 2.96 (dd, J = 6.4, 14.0 Hz, 1H),
2.65-2.51 (m, 2H); 13C NMR (CDCl3, 100 MHz) δ 174.2, 170.4, 156.2,
144.4, 143.7, 141.3, 135.6, 129.6, 129.5, 128.6, 128.2, 127.9, 127.2, 127.0,
125.2, 125.1, 120.1, 67.5, 67.3, 54.0, 53.3, 47.1, 37.4, 33.5; IR (neat):
3402, 3059, 2947, 1715, 1695, 1520, 1489, 1216, 1032, 738, 699, 620 cm-
1; [α]30D = +7.20 (c 0.96, CH2Cl2); mp 115-117 °C; HRMS (ESI-TOF): calcd
for [C46H40N2O5S-H]- 731.2585, found 731.2581.
1717, 1649, 1521, 1367, 1166, 698 cm-1; [α]30 = +44.6 (c 1.00, 25%
D
MeOH in CH2Cl2); mp 136-138 °C; HRMS (ESI-TOF): calcd for
[C25H31N3O6-H]- 468.2140, found 468.2143.
Boc-L-Ala-L-Ser-L-Phe-L-Gly-OH (4n)
A solution of Boc-L-Ala-L-Ser(O-Bn)-OH (1a) (0.333 M, 1.00 equiv.), NMM
(0.333 M, 1.00 equiv.), and DIEA (0.333 M, 1.00 equiv.) in MeCN (flow
rate: 1.20 mL/min) and a solution of isobutyl chloroformate (0.240 M, 1.20
equiv.) in MeCN (flow rate: 2.00 mL/min) were introduced to the T-shape
mixer at 20 °C with the syringe pumps. The resultant mixture was passed
through a reaction tube (inner diameter: 0.800 mm, length: 531 mm,
volume 267 µL, reaction time: 5.00 s) at the same temperature. Then, the
resultant mixture and a solution of H-L-Phe-Gly-ONa[37] (3f) (0.340 M, 1.70
equiv.) in H2O (flow rate: 2.00 mL/min) were introduced to the V-shape
mixer at 20 °C. The resultant mixer was passed through a reaction tube
(inner diameter: 0.800 mm, length 1724 mm, volume: 867 µL, reaction time
10.0 s) at the same temperature. After being eluted for 50 s to reach a
steady state, the resultant mixture was poured into a solution of saturated
aqueous NH4Cl, H2O and EtOAc for 60 s. The aqueous layer was acidified
to pH of 1 with aqueous 1 M HCl and extracted 3 times with EtOAc. The
combined organic layer was washed with aqueous 1 M HCl and brine,
dried over MgSO4, filtered and concentrated in vacuo. The residue was
purified by GPC to afford 4o (149 mg, 0.261 mmol, 65%, epimer: <0.1%).
White solid. HPLC conditions: DAICEL CHIRALPAK IB 4.6 mm×25 cm,
8% IPA (containing 0.1% formic acid) in hexane (containing 0.1% formic
acid), 40 °C, flow rate 1 mL/min, detection wavelength 254 nm, retention
time 41.50 min (epimer 23.69 min). 1H NMR (CDCl3+CD3OD, 500 MHz) δ
7.33-7.27 (m, 2H), 7.27-7.23 (m, 3H), 7.19-7.11 (m, 5H), 4.75 (q, J = 4.38
Hz, 1H), 4.51-4.42 (m, 3H), 4.11 (d, J = 6.5 Hz, 1H), 3.87-3.79 (m, 1H),
3.77-3.68 (m, 2H), 3.65-3.58 (m, 1H), 3.24 (dd, J = 4.7, 15.1 Hz, 1H), 2.96
(dd, J = 9.0, 14.1 Hz, 1H), 1.38 (s, 9H), 1.25 (d, J = 6.8 Hz, 3H); 13C NMR
(CDCl3+CD3OD, 100 MHz) δ 174.2, 171.7, 171.4, 170.0, 156.1, 137.0,
136.5, 128.7, 128.1, 128.0, 127.6, 127.4, 126.3, 79.9, 73.0, 68.7, 57.1,
Cbz-L-Phg-L-Phe-OH (4k)
The reaction mixture was collected for 120 s. Purification method: The
crude product was purified by column chromatography on silica gel
(MeOH : CHCl3 = 1 : 99 to 15 : 95). HPLC conditions: DAICEL CHIRALPAK
IB 4.6 mm×25 cm, 10% IPA (containing 0.1% formic acid) in hexane
(containing 0.1% formic acid), 40 °C, flow rate 1 mL/min, detection
wavelength 254 nm, retention time 12.14 min (epimer 15.75 min). 306 mg,
0.707 mmol, 88% (epimer: <0.1%). White solid; 1H NMR (CDCl3+CD3OD,
400 MHz) δ 7.43-7.06 (m, 15H), 5.31 (s, 1H), 5.11-5.01 (m, 2H), 4.71 (t, J
= 6.9 Hz, 1H) 3.19 (dd, J = 5.3, 13.4 Hz, 1H), 3.00 (dd, J = 7.3, 13.7 Hz,
1H); 13C NMR (CDCl3+CD3OD, 125 MHz) δ 175.2, 170.1, 156.1, 136.9,
136.8, 135.8, 128.9, 128.1, 127.8, 127.6, 127.5, 127.5, 127.3, 126.6, 125.8,
66.4, 58.7, 55.1, 37.0; IR (neat): 3417, 2109, 1692, 1644, 1549, 1404,
1252, 1107, 1014, 699 cm-1; [α]30D = +55.6 (c 1.03, 25% MeOH in CH2Cl2);
mp 220-222 °C; HRMS (ESI-TOF): calcd for [C25H24N2O5-H]- 431.1612,
found 431.1612.
Boc-L-Ala-L-Cys(Trt)-L-Phe-OH (4l)
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