A. Palmioli et al.
Bioorganic Chemistry 109 (2021) 104739
+
calculated for [C16
H
19
N
3
O
5
] 333.13; found 334.2 [M + H] , 356.2 [M
J = 2.6 Hz, 1H, H4), 4.42 (d, J = 5.3 Hz, H10* minor isomer), 4.26–4.21
+
+
′
+
Na] , 351.3 [M + H
2
O + H] .
(m, 1H, H6 ), 4.22–4.16 (m, 1H, H8), 4.13 (dd, J = 12.6, 2.2 Hz, 1H,
′
′
GRPR-L1. To a stirred solution of 8 (28.3 mg, 0.033 mmol) in
H6 ), 4.11–4.05 (m, 1H, H2), 4.02–3.98 (m, minor isomer), 3.81 (dd, J
◦
′
anhydrous MeOH (1.7 mL), formic acid (87
μ
L) was slowly added at 0 C
= 5.5, 2.1 Hz, 1H, H3), 3.68–3.60 (m, 2H, H5, H9 ), 3.54 (dd, J = 13.8,
◦
′′
′
and the resulting mixture was heated at 50 C and stirred for 5 h under
4.2 Hz, 1H, H9 ), 2.52 (dt, J = 14.9, 7.8 Hz, H7 * minor isomer), 2.38
′
argon atmosphere. Then, reaction was quenched by addition of Et
3
N
(dt, J = 14.3, 7.4 Hz, 1H, H7 ), 1.85 (ddd, J = 13.9, 6.2, 2.6 Hz, 1H,
′′
13
(
100 L) and concentrated under reduced pressure. The crude was pu-
μ
H7 ). C NMR (100 MHz, Methanol‑d ) δ 170.49 (CO), 139.67 (Cq),
4
rified by automated flash chromatography (AcOEt:MeOH gradient
135.81 (Cq), 134.57 (C11), 132.68, 129.97, 129.58, 129.55, 129.19,
129.14, 128.41, 128.38, 128.30, 127.45, 119.98 (C12), 105.09 (C15*
minor isomer), 101.80 (C15), 84.33 (C2), 81.52 (C3), 78.60 (C1), 78.51
(C8), 74.05 (C4), 73.52 (C6), 68.79 (C5), 65.59 (C10* minor isomer),
63.57 (C10), 45.22 (C9), 36.76 (C7). MS (ESI) calculated for
elution) obtaining pure compound GRPR-L1 (19 mg, 91% yield). TLC
1
RF = 0.27 (AcOEt:MeOH 9:1). H NMR (400 MHz, Chloroform-d) δ 8.49
(
d, J = 8.5 Hz, 1H, Harom), 8.40 (d, J = 8.6 Hz, 1H, H14), 8.37 (d, J =
8
8
7
.6 Hz, H14* minor isomer), 8.20 (ddd, J = 7.3, 2.8, 1.3 Hz, 1H, Harom),
.15 (s, 1H, H13), 8.08 (s, minor isomer), 7.58–7.41 (m, 3H, Harom),
.39–7.31 (m, 3H, CH Ph), 7.31–7.27 (m, 2H, CH Ph), 7.15–7.08 (m, 2H,
+
+
[C27
H
29
N
3
O
6
] 491.20; found 492.2 [M + H] , 514.2 [M + Na] , 530.2
+
[M + K] .
H12, Harom), 6.98 (s, minor isomer), 5.67 (s, H15* minor isomer), 5.42
GRPR-L4. To a stirred solution of 10 (26 mg, 0.033 mmol) in
′
◦
(
s, 1H, H15), 5.05–4.93 (m, 1H, H1), 4.74 (d, J = 12.8 Hz, 1H, H10 ),
anhydrous MeOH (1.5 mL), formic acid (75
μ
L) was slowly added at 0 C
′′
′
◦
4
.66 (d, J = 12.5 Hz, 1H, H10 ), 4.55 (d, J = 12.6 Hz, H10 * minor
and the resulting mixture was heated at 50 C and stirred for 5 h under
′′
isomer), 4.50–4.41 (m, H10 * minor isomer), 4.38 (t, J = 2.5 Hz, 1H,
argon atmosphere. Then, reaction was quenched by addition of Et
3
N
′′
′
H4), 4.23–4.07 (m, 3H, H2, H8, H6 ), 3.95 (d, J = 12.2 Hz, 1H, H6 ),
(150 L) and concentrated under reduced pressure. The crude was pu-
μ
3
.85 (dt, J = 5.4, 2.6 Hz, 1H, H3), 3.67 (dt, J = 8.6, 4.5 Hz, minor
rified by automated flash chromatography (AcOEt:MeOH gradient
′
isomer), 3.59 (d, J = 5.9 Hz, 1H, H6 * minor isomer), 3.44 (bm, 1H, H5),
elution) obtaining pure compound GRPR-L4 (16.4 mg, 92% yield). TLC
′
1
3
.24 (dd, J = 14.2, 4.1 Hz, H9 * minor isomer), 3.08 (qt, J = 9.8, 5.4 Hz,
RF = 0.15 (AcOEt:MeOH 9:1). H NMR (400 MHz, Methanol‑d
4
) δ 8.34
′
2
H, H9), 2.84 (s, 6H, NMe), 2.30 (dt, J = 14.7, 7.4 Hz, H7 * minor
(s, 1H, H14), 8.08 (s, 1H, H12), 7.78–7.65 (m, 2H, Harom), 7.55–7.49
(m, 1H, minor isomer), 7.48–7.40 (m, 2H, Harom), 7.35 (m, 4H,
Harom), 6.80–6.63 (m, 2H, Harom), 5.74 (s, H15*minor isomer), 5.54
(s, 1H, H15), 5.17–4.99 (m, 1H, H1), 4.72 (s, 2H, H10), 4.54–4.49 (m,
′
isomer), 2.07 (td, J = 13.4, 12.6, 6.1 Hz, 1H, H7 ), 2.00 (d, J = 13.6 Hz,
′′
′′
13
H7 * minor isomer), 1.65–1.55 (m, 1H, H7 ). C NMR (100 MHz,
CDCl ) δ 151.95, 151.91 (Cq N), 137.76 (Cq S), 136.64 (Cq), 135.47
C11), 135.30, 132.42, 131.50, 130.43, 130.29, 130.01, 129.94 (Cq),
3
′
(
1H, H4), 4.47–4.34 (m, H10* minor isomer), 4.29–4.21 (m, 1H, H6 ),
1
1
1
29.72 (Cq), 129.68, 129.29, 129.23, 129.05, 128.83, 128.51, 128.42,
28.39, 127.88, 127.45, 126.41, 123.35, 119.42, 119.22, 118.50,
15.40, 115.34, 104.09, 100.81 (C15), 82.68 (C2), 80.17 (C3), 77.66
4.15 (m, 2H, H6‘’, H8), 4.08 (t, J = 4.5 Hz, 1H, H2), 4.03–3.90 (m, minor
isomer), 3.80 (d, J = 5.4 Hz, 1H, H3), 3.67–3.63 (m, 1H, H5), 3.62–3.56
′
′
′
(m, 1H, H9 ), 3.56–3.49 (m, 1H, H9 ), 3.01 (s, 6H, NMe), 2.99 (s, NMe,
′
(
C8), 76.54, 75.15, 74.54, 74.28, 72.87 (C4), 72.41 (C6), 72.31, 72.05,
9.98, 67.47, 67.05 (C5), 65.14, 63.64, 61.65 (C10), 47.39 (C9), 45.54
NMe), 45.13, 36.40, 35.17 (C7). MS (ESI) calculated for [C32 S]
minor isomer), 2.50 (dt, J = 14.8, 7.8 Hz, H7 * minor isomer), 2.43–2.29
′
′′ 13
6
(m, 1H, H7 ), 1.84 (dd, J = 14.7, 10.2 Hz, 1H, H7 ). C NMR (100 MHz,
(
H
36
N
4
O
7
3
CD OD) δ 170.66, 170.59 (CO), 154.27, 154.24, 139.66, 138.38,
+
+
+
6
20.23; found 621.5 [M + H] , 643.3 [M + Na] , 655.3 [M + K] .
130.70, 130.49, 129.98, 129.88, 129.76, 129.19, 129.15, 128.40,
127.45, 121.94, 121.69, 119.84, 112.18, 112.11, 112.07, 105.08,
101.81 (C15), 84.08 (C2), 81.64 (C3), 78.70 (C8), 78.57 (C1), 78.45,
75.84, 75.62, 74.04 (C4), 73.60, 73.48 (C6), 73.32, 70.77, 68.76 (C5),
68.73, 65.14, 63.13 (C10), 45.08 (C9), 43.34, 40.24, 40.23 (NMe),
GRPR-L2. To a stirred solution of 9 (32 mg, 0.044 mmol) in anhy-
◦
drous MeOH (1 mL), TFA (1 mL) was slowly added at 0 C and the
◦
resulting mixture was heated at 50 C and stirred for 5 h under argon
atmosphere. Then, reaction was quenched by addition of Et
and concentrated under reduced pressure. The crude was purified by
automated flash chromatography (RP18, H O:MeOH gradient elution)
3
N (100
μL)
34 4 6
38.13, 36.69 (C7). MS (ESI) calculated for [C29H N O ] 534.25; found
+
+
2
535.2 [M + H] , 557.2 [M + Na] .
obtaining pure compound GRPR-L2 (17 mg, quant % yield). TLC RF =
GRPR-L5. To a stirred solution of 11 (26 mg, 0.33 mmol) in anhy-
.10 (AcOEt:MeOH 7:3). 1H NMR (400 MHz, Methanol‑d
) δ 8.87 (bs,
drous MeOH (1.6 mL), formic acid (75
μ
L) was slowly added at 0 C and
◦
0
1
7
4
◦
H, H13), 7.87–7.79 (m, 2H, Harom), 7.58–7.50 (m, 2H, H12, H14),
the resulting mixture was heated at 50 C and stirred for 5 h under argon
atmosphere. Then, reaction was quenched by addition of Et N (100 L)
.50–7.40 (m, 3H, Harom), 4.78 (d, J = 2.2 Hz, 1H, H10), 4.58 (m, 1H,
3
μ
H1), 4.31–4.20 (m, 1H, H8), 4.17 (bt, 1H, H4), 4.01 (dd, J = 10.1, 5.3
and concentrated under reduced pressure. The crude was purified by
automated flash chromatography (AcOEt:MeOH gradient elution)
obtaining pure compound GRPR-L5 (13 mg, 83% yield). TLC RF = 0.16
′′
′
Hz, 1H, H2), 3.91–3.76 (m, 2H, H5, H6 ), 3.75–3.61 (m, 2H, H3, H6 ),
3
1
.57 (ddd, J = 21.6, 13.3, 5.2 Hz, 2H, H9), 2.30 (dq, J = 14.3, 7.3 Hz,
13
′′
′
1
H, H7 ), 1.89 (m, 1H, H7 ). C NMR (101 MHz, Methanol‑d
4
) δ 170.47
(AcOEt:MeOH 9:1). H NMR (400 MHz, Chloroform-d) δ 7.87–7.76 (m,
(
CO), 135.67 (Cq), 132.74, 132.69 (C12, C14), 132.133 (C11), 129.64,
3H, Harom), 7.58–7.48 (m, 1H, H14), 7.45–7.29 (m, 5H, Harom), 7.01
(s, 1H, H12), 6.87 (m, 2H, Harom), 5.74 (s, minor isomer), 5.46 (s, 1H,
H15), 5.13 (ddd, J = 6.7, 4.3, 2.1 Hz, 1H, H1), 4.71 (dd, J = 13.3, 9.2 Hz,
2H, H10), 4.66–4.56 (m, minor isomer), 4.50 (d, J = 12.4 Hz, minor
1
7
29.58, 128.24 (Carom), 82.51 (C2), 81.47 (C3), 78.18 (C8), 78.05 (C5),
4.49 (C1), 67.31 (C4), 61.71 (C10), 60.88 (C6), 45.31 (C9), 35.42 (C7).
MS (ESI) calculated for [C20
H
25
3
N O
6
] 403.17; found 404.1 [M + H]+,
+
′
4
26.1 [M + Na] .
isomer), 4.42–4.37 (m, 1H, H4), 4.31 (m, 2H, H8, H6 ), 4.23 (dd, J = 8.3,
GRPR-L3. To a stirred solution of 9 (15 mg, 0.02 mmol) in anhy-
1.7 Hz, minor isomer), 4.13 (t, J = 4.9 Hz, 1H, H2), 4.05 (dd, J = 12.9,
◦
′′
drous MeOH (1 mL), formic acid (54
μ
L) was slowly added at 0 C and
2.2 Hz, 1H, H6 ), 4.01–3.87 (m, minor isomer), 3.80 (s, 1H, minor
◦
′′
the resulting mixture was heated at 50 C and stirred for 5 h under argon
atmosphere. Then, reaction was quenched by addition of Et N (100 L)
isomer), 3.79 (s, 3H, OMe), 3.78–3.69 (m, 2H, H3, H9 ), 3.63–3.55 (m,
′
3
μ
1H, H9 ), 3.53 (s, 1H, H5), 2.50 (dt, J = 15.1, 8.1 Hz, minor isomer),
′
′
′
13
and concentrated under reduced pressure. The crude was purified by
automated flash chromatography (AcOEt:MeOH gradient elution)
2.37 (dq, J = 15.2, 7.6 Hz, 1H, H7 ), 1.92–1.76 (m, 1H, H7 ). C NMR
(100 MHz, CDCl ) δ 167.92 (CO), 167.81, 162.42, 162.25 (Cq), 137.78
3
obtaining pure compound GRPR-L3 (10 mg, quant % yield). TLC RF =
(Cq), 136.54 (C11), 130.09, 129.34, 129.13, 129.08, 128.56, 128.46,
127.45, 126.79 (Cq), 126.43, 126.37, 113.87, 113.79, 104.20, 100.84
(C15), 83.34 (C2), 79.59 (C3), 77.77 (C8), 77.51 (C1), 76.98, 74.76,
74.15, 72.97, 72.68 (C6), 72.28, 72.18, 69.95, 67.92, 67.54 (C5), 64.52,
61.92 (C10), 55.56, 55.54 (OMe), 44.02 (C9), 43.18, 37.72, 35.95 (C7).
1
0
.19 (AcOEt:MeOH 9:1). H NMR (400 MHz, Methanol‑d
4
) δ 8.36 (s, 1H,
H13), 7.90 (s, 1H, H14), 7.82 (m, 2H, Harom), 7.56–7.49 (m, 1H,
Harom), 7.49–7.39 (m, 5H, Harom), 7.39–7.30 (m, 3H, Harom), 7.17 (s,
1
5
1
H, H12), 7.09 (s, H12* minor isomer), 5.74 (s, H15* minor isomer),
.54 (s, 1H, H15), 5.10 (ddd, J = 7.1, 4.5, 2.7 Hz, 1H, H1), 4.71 (dd, J =
2.8, 2.2 Hz, 2H, H10), 4.64 (dd, J = 8.4, 2.5 Hz, minor isomer), 4.51 (t,
MS (ESI) calculated for [C28
H
31
N
3
O
7
] 521.22; found 522.2 [M + H]+,
544.3 [M + Na]+.
8