6150
V. Jithender Reddy et al. / Tetrahedron Letters 53 (2012) 6148–6150
11. (a) Analytical data of compound 11: Rf = 0.5 silica gel, 10% EtOAc in Petroleum
ether). ½a D25 = +6.8 (c 3.5, CHCl3). IR (neat): max (br) 3441, 2924, 17111, 1498,
1366, 1167, 741 and 700 cmꢀ1 1H NMR (CDCl3, 300 MHz): d 7.38–7.13 (m,
ꢁ
m
OH
.
BocHN
BocHN
10H), 5.39 (dt, J = 10.5, 7.5 Hz, 1H), 5.13 (t, J = 10.5 Hz, 1H), 5.02–4.86 (m, 2H),
4.55 (ddd, J = 14.3, 6.8, 6.0 Hz, 1H), 4.47–4.37 (m, 2H), 3.42–3.26 (m, 2H), 3.10
(dd, J = 14.3, 6.0 Hz, 1H), 2.92 (dd, J = 14.3, 7.5 Hz, 1H), 2.71 (dt, J = 9.8, 6.7 Hz,
1H), 2.06–1.86 (m, 2H), 1.80–1.50 (m, 2H), 1.35–1.20 (m, 13H), 0.97–0.82 (m,
6H). 13C NMR (CDCl3, 75 MHz): d 171.7, 154.9, 138.2, 136.2, 131.1, 130.4, 129.3,
128.4, 128.3, 127.6, 127.5, 126.8, 79.6, 76.5, 72.9, 66.6, 54.4, 38.1, 35.6, 32.1,
31.7, 28.2, 27.2, 22.2, 16.8, 13.9. mass (ESIMS): m/z 524 [M+H]+, 546 [M+Na]+.
(b) Analytical data of compound 12: Rf = 0.5 (silica gel, 10% EtOAc in Petroleum
OH
BocHN
O
O
i, ii
iii, iv
H
N
COOH
TFA.H2N
H
N
ether). ½a D25
ꢁ
= ꢀ23.9 (c 2.5, CHCl3). IR (neat):
mmax (br) 3619, 2923, 1707, 1647,
COOMe
1515, 1462, 1169, and 742 cmꢀ1
.
1H NMR (CDCl3, 300 MHz): d 7.35–7.15 (m,
O
10H), 5.41 (dt, J = 11.3, 7.5 Hz, 1H), 5.17 (m, 1H), 5.04 (dd, J = 11.3, 6.0 Hz, 1H),
4.91 (d, J = 8.3 Hz, 1H), 4.53 (m, 1H), 4.49–4.39 (m, 2H), 3.50–3.33 (m, 2H), 3.14
(dd, J = 14.3, 6.0 Hz, 1H), 2.93 (dd, J = 14.3, 6.7 Hz, 1H), 2.70 (m, 1H), 2.06–1.93
(m, 2H), 1.81 (dd, J = 12.8, 6.0 Hz, 2H), 1.44–1.24 (m, 13H), 0.97–0.83 (m, 6H).
13C NMR (CDCl3, 75 MHz): d 171.8, 155.0, 138.3, 136.1, 131.5, 130.0, 129.3,
128.4, 128.2, 127.7, 127.5, 126.8, 79.7, 75.8, 73.1, 66.6, 54.5, 38.1, 35.5, 31.8,
31.7, 28.2, 27.1, 22.3, 16.8, 13.9. mass (ESIMS): m/z 524 [M+H]+, 546 [M+Na]+.
(c) Analytical data of compound 13: Rf = 0.5 (silica gel, 10% EtOAc in Petroleum
20
O
21
v
O
O
H
N
H
N
R
BocHN
N
H
O
ether). ½a D25
ꢁ
= +26.1 (c 2.2, CHCl3). IR (neat): mmax 2921, 2851, 1716, 1365,
O
O
1214, 1168, and 746 cmꢀ1
.
1H NMR (CDCl3, 300 MHz): d 7.38–7.12 (m, 10H),
5.40 (dt, J = 10.9, 6.7 Hz, 1H), 5.15 (t, J = 10.2 Hz, 1H), 5.06–4.86 (m, 2H), 4.55
(dd, J = 14.1, 6.4 Hz, 1H), 4.49–4.37 (m, 2H), 3.44–3.28 (m, 2H), 3.09 (dd,
J = 14.1, 6.4 Hz, 1H), 2.96 (dd, J = 14.1, 6.0 Hz, 1H), 2.71 (m, 1H), 2.07–1.92 (m,
2H), 1.79 (dd, J = 12.6, 6.2 Hz, 2H), 1.44–1.23 (m, 13H), 0.95–0.84 (m, 6H). 13C
NMR (CDCl3, 75 MHz): d 171.6, 154.9, 138.3, 136.2, 131.5, 129.8, 129.3, 128.4,
128.3, 127.7, 127.5, 126.8, 79.7, 76.1, 73.0, 66.7, 54.5, 38.2, 35.2, 31.8, 31.7,
28.2, 27.1, 22.3, 16.8, 13.9. Mass (ESIMS): m/z 524 [M+H]+, 546 [M+Na]+.
12. Chakraborty, T. K.; Ghosh, S.; Jayaprakash, S.; Sharma, J. A. R. P.; Ravikanth, V.;
Diwan, P. V.; Nagraj, R.; Kunwar, A. C. J. Org. Chem. 2000, 65, 6441–6457.
13. Analytical data of compound 22 Rf = 0.4 (silica gel, 80% EtOAc in Petroleum
22: R = CH3
23: R = H
ii
Scheme 4. Reagents and conditions: (i)
to rt, 95%.; (ii) LiOH, THF:MeOH:H2O (3:1:1); (iii)
L
-Val-OMe, EDCI, HOBT, DIPEA, CH2Cl2, 0 °C
-Ala-OMe, EDCI, HOBT, DIPEA,
L
CH2Cl2, 0 °C to rt, 97%.; (iv) TFA, CH2Cl2, 0 °C.; (v) EDCI, HOBT, DIPEA, CH2Cl2, 0 °C to
rt, 94%.
ether). ½a D25
ꢁ
= ꢀ49.0 (c 0.5, CHCl3). IR (neat): mmax 3285, 2962, 1641, 1544,
i
1368, 1164 and 754 cmꢀ1
.
1H NMR (CDCl3, 500 MHz): d 7.45–7.35 (m, 2H), 6.99
8 9 10
/ /
11/12/13
(d, J = 7.0 Hz, 1H), 5.53 (t, J = 5.4 Hz, 1H), 4.61–4.52 (m, 2H), 4.40 (t, J = 7.8 Hz,
1H), 4.00–3.84 (m, 2H), 3.72 (s, 3H), 2.09 (td, J = 7.0, 7.0, 20.2, 1H), 1.75–1.62
(m, 2H), 1.55 (m 1H), 1.44 (s, 9H), 1.38 (d, J = 7.8 Hz, 3H), 0.96–0.87 (m, 12H).
13C NMR (CDCl3, 75 MHz): d 173.0, 171.9, 171.3, 169.3, 156.1, 58.1, 52.2, 51.6,
47.9, 43.9, 41.1, 31.7, 28.2, 24.5, 22.5, 22.3, 19.0, 18.3, 17.5. Mass (ESIMS): m/z
473 [M+H]+, 495 [M+Na]+.
ii
O
H
N
H
N
NH
N
H
Ph
14. Vatele, J. M. Tetrahedron Lett. 2006, 47, 715–718.
iii
O
15. (a) Reddy, K. M.; Shashidhar, J.; Reddy, P. G.; Ghosh, S. Tetrahedron Lett. 2011,
52, 5987–5991; (b) Han, S. Y.; Kim, Y. A. Tetrahedron 2004, 60, 2447–2467.
16. (a) Analytical data of compound 2: Rf = 0.4 (silica gel, 6% MeOH in CHCl3).
O
5/6 7
/
O
O
O
29
NHBoc
28
HO
½
aꢁD25
= ꢀ43.7 (c 0.08, CHCl3). IR (neat):
mmax (br) 3330, 2958, 2925, 1639, 1531,
iv
and 672 cmꢀ1 1H NMR (CDCl3, 500 MHz): d 8.23 (d, J = 7.1 Hz, 1H), 8.13 (d,
.
24: 28R, 29R
25
: 28S, 29R
26: 28R, 29S
J = 7.1 Hz, 1H), 7.91–7.82 (m, 3H), 7.28–7.14 (m, 5H), 5.03 (m, 1H), 4.35 (ddd,
J = 8.7, 7.1, 5.5 Hz 1H), 4.11–4.00 (m, 3H), 3.93 (t, J = 7.9 Hz, 1H), 3.83 (d,
J = 5.5 Hz, 1H), 3.10 (dd, J = 14.2, 5.5 Hz, 1H), 3.0 (dd, J = 14.2, 8.7 Hz, 1H), 2.46
(m, 1H),2.33 (d, J = 13.4 Hz, 1H), 2.06 (m, 1H), 1.75–1.61 (m, 2H), 1.55 (m, 1H),
1.48 (m, 1H), 1.27 (d, J = 7.1 Hz, 3H), 1.24–1.10 (m, 10H), 0.88 (two d, J = 6.3 Hz,
6H), 0.85 (d, J = 6.3 Hz, 3H), 0.84–0.80 (m, 6H), 0.76 (d, J = 6.7 Hz, 3H). 13C NMR
(CDCl3, 75 MHz): d 171.8, 171.3, 170.6, 169.9, 169.8, 169.6, 138.1, 128.8, 128.1,
126.1, 75.2, 59.5, 54.2, 52.3, 48.5, 42.3, 38.1, 37.8, 35.9, 31.3, 31.1, 29.9, 29.8,
26.4, 24.2, 22.9, 22.1, 21.1, 19.1, 18.2, 17.6, 14.7, 13.9. HRMS (ESIMS): calcd for
2/3/4
Scheme 5. Reagents and conditions: (i) (a) TFA, CH2Cl2, 0 °C; (b) 23, EDCI, HOBT,
DIPEA, CH2Cl2, 0 °C to rt; 90% (24), 93% (25), 91% (26); (ii) H2, 10%Pd-C, MeOH, 98%;
(iii) (a) TEMPO, BAIB-CH3CN:H2O (2:1), 0 °C to rt, 2 h; (b) TFA, CH2Cl2, 0 °C; (iv)
HATU, HOAT, DIPEA, CH2Cl2, 0 °C to rt, 56% (2), 54% (3) and 59% (4) over three steps.
C
36H57N5O7Na [M+Na]+ = 694.4150, found: 694.4156.
(b) Analytical data of compound 3: Rf = 0.4 (silica gel, 6% MeOH in CHCl3).
= ꢀ12.5 (c 0.08, CHCl3). IR (neat): mmax 3308, 2926, 2858, 1749, 1639,
1543, 1173 and 694 cmꢀ1 1H NMR (CDCl3, 500 MHz): d 8.40 (d, J = 4.5 Hz, 1H),
Acknowledgments
½aꢁD25
.
The authors wish to thank CSIR (V.J.R.) and UGC (T.K.P.), New
Delhi for research fellowships. We are also thankful to Professor
Fenical for providing natural arenamide A.
8.01 (d, J = 9.0 Hz, 1H), 7.86 (d, J = 7.5 Hz, 1H), 7.60 (t, J = 4.5 Hz, 1H), 7.29–7.19
(m, 6H), 4.90 (dd, J = 7.5, 4.5 Hz, 1H), 4.28–4.18 (m, 2H), 4.15–4.05 (m, 2H),
3.94 (t, J = 7.5 Hz, 1H), 3.77 (dd, J = 16.5, 4.5 Hz, 1H), 2.99 (dd, J = 13.5, 6 Hz,
1H), 2.87 (dd, J = 13.5, 9.0 Hz, 1H), 2.45 (m, 1H), 2.11 (d, J = 13.5 Hz, 1H), 1.93
(m, 1H), 1.61–1.50 (m, 3H), 1.36–1.06 (m, 12H), 1.0 (m, 1H), 0.93–0.85 (m,
12H), 0.83 (d, J = 4.5 Hz, 3H), 0.43 (d, J = 6.0 Hz, 3H). 13C NMR (CDCl3, 75 MHz):
d 171.6, 171.2, 170.8, 169.4, 169.0, 168.9, 136.2, 129.1, 128.3, 126.7, 75.1, 60.3,
54.9, 51.4, 47.2, 42.2, 37.2, 36.7, 35.2, 31.7, 31.1, 29.7, 28.5, 26.2, 24.3, 23.2,
22.0, 20.6, 19.0, 18.6, 18.5, 13.9, 13.8. HRMS (ESIMS): calcd for C36H57N5O7Na
[M+Na]+ = 694.4150, found: 694.4154.
References and notes
1. Asolkar, R. N.; Freel, K. C.; Jensen, P. R.; Fenical, W.; Kondratyuk, T. P.; Park, E. J.;
Pezzuto, J. M. J. Nat. Prod. 2009, 72, 396–402.
2. Chandrasekhar, S.; Pavankumarreddy, J.; Sathish, K. Tetrahedron Lett. 2009, 50,
6851–6854.
3. Asolkar, R. N.; Freel, K. C.; Jensen, P. R.; Fenical, W.; Kondratyuk, T. P.; Park, E. J.;
Pezzuto, J. M. J. Nat. Prod. 2010, 73, 796.
(c) Analytical data of compound 4: Rf = 0.4 (silica gel, 6% MeOH in CHCl3);
½
a D25
ꢁ
= ꢀ4.0 (c 0.07, CHCl3); IR (neat): mmax 3301, 2926, 1648, 1535, 1248 and
696 cmꢀ1 1H NMR (CDCl3, 500 MHz):
.
d
8.20 (d, J = 7.1 Hz, 1H), 8.08 (d,
J = 7.1 Hz, 1H), 7.93–7.81 (m, 3H), 7.28–1.13 (m, 5H), 4.99 (m, 1H), 4.35 (dd,
J = 13.4, 7.9 Hz, 1H), 4.11–4.01 (m, 2H), 3.91 (t, J = 7.1 Hz, 1H), 3.88–3.79 (m,
2H), 3.13 (dd, J = 14.2, 5.5 Hz, 1H), 3.01 (dd, J = 14.2, 9.5 Hz, 1H), 2.44 (dd,
J = 15.0, 9.5 Hz, 1H), 2.35 (d, J = 13.4 Hz, 1H), 2.06 (m, 1H), 1.75–1.61 (m, 2H),
1.56 (m, 1H), 1.48 (m, 1H), 1.26 (d, J = 6.3 Hz, 3H), 1.24–1.10 (m, 10H), 0.91–
0.86 (m, 9H), 0.85 (d, J = 6.3 Hz, 3H), 0.82 (d, J = 6.3 Hz, 3H), 0.74 (d J = 6.3 Hz,
3H). 13C NMR (CDCl3, 75 MHz): d 172.0, 171.4, 170.4, 170.0, 169.9, 169.7, 138.1,
128.7, 128.0, 126.0, 75.5, 59.8, 54.2, 52.3, 48.1, 42.1, 36.7, 35.3, 31.7, 31.1, 29.6,
28.8, 28.6, 26.2, 24.2, 22.9, 21.9, 21.0, 19.0, 18.1, 17.7, 14.1, 13.8. HRMS
(ESIMS): calcd for C36H58N5O7 [M+H]+ = 672.4330, found: 672.4337.
4. Ghosh, S.; Pradhan, T. K. Tetrahedron Lett. 2008, 49, 5303–5310.
5. (a) Crimmins, M. T.; She, J. Synlett 2004, 1371–1374; (b) Tian, H.; Jiao, H.; Xie,
P.; Liang, H. Tetrahedron Lett. 2005, 46, 8579–8581.
6. Lorenz, M.; Kalesse, M. Tetrahedron Lett. 2007, 48, 2905–2907.
7. Mancuso, A. J.; Swern, D. Synthesis 1981, 165–185.
8. Harchken, C.; Martin, S. F. Org. Lett. 2001, 3, 3591–3595.
9. Gurjar, M. K.; Nagaprasad, R.; Ramana, C. V. Tetrahedron Lett. 2003, 44, 2873–
2875.
10. (a) Dodge, J. F.; Trujillo, J. I.; Presnell, M. J. Org. Chem. 1994, 59, 234–236; (b)
Ahn, C.; Correia, R.; Deshong, P. J. Org. Chem. 2002, 67, 1751–1753.