Total syntheses of telisatin A, telisatin B and lettowianthine

Article abstract of DOI:10.3390/molecules14030917

Treatment of 1-(2-bromoarylmethyl)-3,4-dihydroisoquinolines with oxalyl chloride and triethylamine gave 1-(2-bromophenyl)-5,6-dihydropyrrolo[2,1-a] isoquinoline-2,3-dione derivatives, for example, 1-(2-bromophenyl)-5,6-dihydro- 8,9-dimethoxypyrrolo[2,1-a]

Full text of DOI:10.3390/molecules14030917

Molecules 2009, 14, 917-924; doi:10.3390/molecules14030917
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molecules
ISSN 1420-3049
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Article
Total Syntheses of Telisatin A, Telisatin B and Lettowianthine
Surachai Nimgirawath * and Phansuang Udomputtimekakul
Department of Chemistry, Faculty of Science, Silpakorn University; Nakorn Pathom 73000, Thailand;
E-mail: Phansuang@yahoo.com (P.U.)
* Author to whom correspondence should be addressed; E-mail: surachai@su.ac.th.
Received: 2 February 2009; in revised form: 17 February 2009/ Accepted: 26 February 2009 /
Published: 26 February 2009
Abstract: Treatment of 1-(2-bromoarylmethyl)-3,4-dihydroisoquinolines with oxalyl
chloride and triethylamine gave 1-(2-bromophenyl)-5,6-dihydropyrrolo[2,1-a]isoquinoline-
2,3-dione
derivatives,
for
example,
1-(2-bromophenyl)-5,6-dihydro-8,9-
dimethoxypyrrolo[2,1-a]isoquinoline-2,3-dione. Radical cyclisation of these derivatives
with tributyltin hydride and 1,1′-azobis(cyclohexanecarbonitrile) afforded telisatin A,
telisatin B and lettowianthine.
Keywords: Alkaloid; Dioxoaporphine; Isoquinoline; Radical cyclisation; Synthesis.
Introduction
The telisatin-type aporphine alkaloids form a very small sub-group of the aporphine alkaloids in
which N-6 and C-7 are fused to an oxalyl function. To date only five members of this type of
aporphine alkaloids have been found to occur in Nature. These are telisatin A (1) and telisatin B (2)
from Telitoxicum peruvianum Moldenke (Menispermaceae) [1], lettowianthine (3) and 11-methoxy-
lettowianthine (4) from Lettowianthus stellatus Diels (Annonaceae) [2], and laurodionine (5) from
Phoebe formosana Hayata (Lauraceae) [3]. Annonbraine, isolated from Annona glaba L
(Annonaceae), was also assigned the same structure as lettowianthine (3), although there was a big
difference in the melting points of the two alkaloids [4]. The structure of telisatin A was elucidated by
comparison of spectral data and physical properties with a synthetic compound obtained by Saa and

Molecules 2009, 14
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Cava [5], Castedo et al. [6] and Saa et al. [7]. The structures of the remaining alkaloids were assigned
based on spectral data analysis.
Figure 1. Structures of telisatin A (1), telisatin B (2), lettowianthine (annonbraine) (3),
11-methoxylettowianthine (4) and laurodionine (5).
R
1
3
4
R
2
5
2
3 a
1 b
N
O
6 a
7
1
6
R
R
1 a
3
4
1 2
1 1 a
1 3
1 1
7 a
O
8
1 0
R
9
5
R
6
1 : R1 = R4 = R5 = R6 = H, R2 = R3 = OCH3 (telisatin A)
2 : R1 = R2 = R3 = OCH3, R4 = R5 =R6 = H (telisatin B)
3 : R1 = R4 = R5 = R6 = H, R2 + R3 = OCH2O (lettowianthine, annonbraine)
4 : R1 = R5 = R6 = H, R2 + R3 = OCH2O, R4 = OCH3 (11-methoxylettowianthine)
5 : R1 = R4 = H, R2 = R6 = OH, R3 = R5 = OCH3 (laurodionine)
At present there are only two total syntheses of telisatin A reported by Castedo et al. [6] and by Saa
et al. [7] The first method involved photochemical cyclisation in reasonably good yield (60%) of a
very dilute (0.001 M) solution of 1-(2-bromophenyl)-5,6-dihydro-8,9-dimethoxypyrrolo[2,1-
a]isoquinoline-2,3-dione (10a) [6]. This method has obvious inherent limitations with regards to its
scalability and convenience. The second method, based on benzyne cycloaddition, gave a low yield
(10%) [7]. A partial synthesis reported by Saa and Cava involved acylation of 6a,7-dehydronuciferine
with oxalyl chloride [5]. Since 6a,7-dehydroaporphines themselves are not readily accessible, this
method therefore lacks generality and convenience.
Results and Discussion
We would like to report herein an extension of the first method described by Castedo et al. [6],
shown in Scheme 1. Amides 8a-8c, obtained by conventional methods, were converted by a Bischler–
Napieralski reaction to dihydroisoquinolines 9a-9c. We found that 1-(2-bromophenyl)-5,6-
dihydropyrrolo[2,1-a]-isoquinoline-2,3-dione derivatives 10a-10c could be more conveniently
prepared by the reaction of dihydroisoquinolines 9a-9c with oxalyl chloride in the presence of
triethylamine with straightforward workup [8]. The antiplatelet activity of such 1-aryl-5,6-
dihydropyrrolo[2,1-a]-isoquinoline-2,3-dione derivatives has been reported [9]. To overcome the
limitations of photochemical cyclisation under extreme dilution and based on previous reports on the
radical cyclisation of halostilbenes to phenanthrenes [10-14], solutions (0.025 M) of 1-(2-

Molecules 2009, 14
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bromophenyl)-5,6-dihydropyrrolo[2,1-a]isoquinoline-2,3-dione derivatives 10a-10c were treated with
tributyltin hydride in the presence of 1,1′-azobis(cyclohexanecarbonitrile) (ACCN) to give the
corresponding telisatin-type alkaloids in 30-34% yields.
Scheme 1. Syntheses of telisatin A (1), telisatin B (2) and lettowianthine (3).
R
1
B r
R
1
R
R
2
3
C l
R
R
2
3
+
N H
2
O
N
A
O
B r
H
6 a , 6 b , 6 c
7
8 a , 8 b , 8 c
R
R
1
1
R
1
6
1
R
R
R
8
2
3
2
3
5
R
R
2
3
7
C
D
B
9
4
N
1 0
O
N
N
O
R
3
B r
B r
2
O
O
1 0 a , 1 0 b , 1 0 c
1 , 2 , 3
9 a , 9 b , 9 c
a : R = H , R = R = O C H
3
2
3
b : R 1 = R = R = O C H
c : R = H , R +3 R = O C H O
1
2
3
1
2
3
2
Reaction conditions: A) 10 % NaHCO3/ chloroform; B) POCl3/ benzene; C) oxalyl
chloride, triethylamine/ chloroform; D) Bu3SnH, ACCN/ dry toluene.
Fortunately, in all cases, it was possible to isolate the pure alkaloids from the crude reaction
mixtures by simple crystallization from ethanol. Silica gel chromatography of the residues from the
filtrates afforded only minute quantities of the pure alkaloids and was therefore not pursued any
further. Comparison of the yields from radical cyclisation using ACCN with those obtained using 2,2′-
azobis(isobutyronitrile)(AIBN) was not possible since AIBN is no longer commercially available in
Thailand. The spectral data of synthetic telisatin A (1), telisatin B (2) and lettowianthine (3) were in
good agreement to those reported for the natural alkaloids.
Conclusions
We have developed an easy and convenient synthesis of the telisatin-type alkaloids. Further
applications of the current synthesis to the remaining telisatin-type alkaloids are in progress.

Molecules 2009, 14
920
Experimental
General
Melting points were determined on a Stuart Scientific SMP 2 melting point apparatus and are
uncorrected. Infrared spectra were recorded on CH2Cl2-films with a Perkin Elmer Spectrum GX FT-IR
spectrophotometer. Ultraviolet spectra were recorded on methanol solutions with a Hitachi U-3300
1
13
spectrophotometer. H- and C-NMR spectra were recorded for deuterochloroform solutions at 300
1
13
MHz for H and 75 MHz for C with a Bruker AVANCE 300 spectrometer. Tetramethylsilane was
used as the internal standard. High Resolution Mass spectra were recorded with a Bruker Daltonics
MicrOTOF mass spectrometer.
N-(3,4-Dimethoxyphenethyl)-2-(2-bromophenyl)acetamide (8a). A mixture of 2-bromophenylacetic
acid (15.0 g, 0.07 mol) and thionyl chloride (20.8 g) in benzene (50 mL) was refluxed for 1 h.
Removal of the solvent under vacuum gave 2-bromophenylacetyl chloride (7) which was dissolved in
ethanol-free chloroform (50 mL) and added to a mixture of 3,4-dimethoxyphenethylamine (6a, 12.7 g,
0.07 mol) in chloroform (100 mL) and 10% sodium hydrogen carbonate (100 mL). The mixture was
then stirred for 3 h and the chloroform layer was washed with water (2 × 100 mL), 10% hydrochloric
acid (3 × 50 mL), water (100 mL), then dried over anhydrous sodium sulfate. Removal of the solvent
under vacuum gave a residue which was recrystallized from ethanol to give amide 8a as a pale yellow
1
solid (22.0 g, 88.1%); m.p. 131-132 °C (Lit. [15] m.p. 127-129 °C); H-NMR: δ 7.54 (1H, d, J = 7.8
Hz, Ar-H); 7.30-7.22 (2H, m, Ar-H); 7.18-7.09 (1H, m, Ar-H); 6.72 (1H, d, J = 8.1 Hz, Ar-H); 6.63
(1H, d, J = 1.9 Hz, Ar-H); 6.60 (1H, dd, J = 8.1, 1.9 Hz, Ar-H); 5.58 (1H, s, NH); 3.85 (3H, s, OCH3);
3.82 (3H, s, OCH3); 3.66 (2H, s, CH2); 3.47 (2H, apparent q, J = 6.8 Hz, CH2); 2.71 (2H, apparent t, J
13
= 7.0 Hz, CH2); C-NMR: δ 169.48(C), 148.98(C), 147.60(C), 134.79(C), 133.03(CH), 131.63(CH),
131.10(C), 129.04(CH), 127.92(CH), 124.94(C), 120.58(CH), 111.79(CH), 111.32(CH), 55.91(OCH3),
55.82 (OCH3), 43.99(CH2), 40.81(CH2), 34.99(CH2).
N-(2,3,4-Trimethoxyphenethyl)-2-(2-bromophenyl)acetamide (8b). In a similar manner, 8b was
obtained in 78.8% yield as a pale yellow solid from ethanol; m.p. 92-93 °C; 1H-NMR: δ 7.57 (1H, d, J
= 8.3 Hz, Ar-H); 7.33-7.25 (2H, m, Ar-H); 7.19-7.12 (1H, m, Ar-H); 6.72 (1H, d, J = 8.5 Hz, Ar-H);
6.54 (1H, d, J = 8.5 Hz, Ar-H); 5.83 (1H, br s, NH); 3.88 (3H, s, OCH3); 3.83 (3H, s, OCH3); 3.79
(3H, s, OCH3); 3.67 (2H, s, CH2); 3.43 (2H, apparent q, J = 6.4 Hz, CH2); 2.70 (2H, apparent t, J = 6.7
Hz, CH2); 13C-NMR: δ 169.58(C), 152.59(C), 151.74(C), 142.19(C), 134.91(C), 133.05(CH),
131.78(CH), 128.97(CH), 127.89(CH), 125.10(C), 124.69(C), 124.46(CH), 107.42(CH), 60.92(OCH3),
60.75(OCH3), 56.01(OCH3), 44.05 (CH2), 40.91(CH2), 29.47(CH2).
N-(3,4-Methylenedioxyphenethyl)-2-(2-bromophenyl)acetamide (8c). In a similar manner, 8c was
obtained in 82.5% yield as a pale yellow solid from ethanol; m.p. 124-126 °C (Lit. [16] m.p. 128-130
1
°C); H-NMR: δ 7.56 (1H, d, J = 7.8 Hz, Ar-H); 7.33-7.25 (2H, m, Ar-H); 7.19-7.11 (1H, m, Ar-H);
6.65 (1H, d, J = 7.9 Hz, Ar-H); 6.55 (1H, d, J = 1.6 Hz, Ar-H); 6.48 (1H, dd, J = 7.9, 1.6 Hz, Ar-H);
5.91 (2H, s, OCH2O); 5.48 (1H, br s, NH); 3.66 (2H, s, CH2); 3.42 (2H, apparent q, J = 6.7 Hz, CH2);

Molecules 2009, 14
921
13
2.65 (2H, apparent t, J = 6.7 Hz, CH2); C-NMR: δ 169.44(C), 147.72(C), 146.11(C), 134.80(C),
133.13(CH), 132.35(C), 131.67(CH), 129.09(CH), 127.97(CH), 124.98(C), 121.57(CH), 109.04(CH),
108.30(CH), 100.85(CH2), 44.04(CH2), 40.87(CH2), 35.15(CH2).
1-(2-Bromobenzyl)-3,4-dihydro-6,7-dimethoxyisoquinoline (9a). A solution of 8a (5.5 g, 14.6 mmol)
and phosphorus oxychloride (17.0 g) in benzene (60 mL) was refluxed for 3 h. The excess reagent and
solvent were removed under vacuum. The residue was shaken with chloroform (100 mL) and dilute
ammonium hydroxide (100 mL). The chloroform layer was washed with water (100 mL), then dried
over anhydrous sodium carbonate. Removal of the solvent under vacuum gave dihydroisoquinoline 9a
as a pale yellow solid (3.9 g, 75.8%) from ethyl acetate-hexane; m.p. 95-96 °C (Lit. [15] m.p. 93-95
°C). It was found to be unstable and was immediately used in the next step without further purification.
1H-NMR: δ 7.56 (1H, dd, J = 7.9, 1.3 Hz, Ar-H); 7.27 (1H, dd, J = 7.6, 1.7 Hz, Ar-H); 7.18 (1H, dt, J
= 7.6, 1.3 Hz, Ar-H); 7.05 (1H, dt, J = 7.6, 1.7 Hz, Ar-H); 6.91 (1H, s, Ar-H); 6.67 (1H, s, Ar-H); 4.20
(2H, s, Ar-CH2); 3.88 (3H, s, OCH3); 3.79 (3H, s, OCH3); 3.73 (2H, t, J = 7.6 Hz, CH2); 2.67 (2H, t, J
= 7.6 Hz, CH2); 13C-NMR δ: 165.08(C), 150.76(C), 147.43(C), 137.66(C), 132.78(CH), 131.59(C),
130.21 (CH), 128.18(CH), 127.62(CH), 124.54(C), 121.41(C), 110.25(CH), 109.15(CH),
56.16(OCH3), 55.92(OCH3), 47.29(CH2), 42.53(CH2), 25.73(CH2).
1-(2-Bromobenzyl)-3,4-dihydro-5,6,7-trimethoxyisoquinoline (9b). In a similar manner, 9b was
obtained in almost quantitative yield as a yellow viscous oil. 1H-NMR: δ 7.55 (1H, dd, J = 7.9, 1.2 Hz,
Ar-H); 7.30-7.26 (1H, m, Ar-H); 7.20-7.15 (1H, m, Ar-H); 7.09-7.01 (1H, m, Ar-H); 6.78 (1H, s,
H−8); 4.19 (2H, s, Ar−CH2); 3.88 (3H, s, OCH3); 3.83 (3H, s, OCH3); 3.78 (3H, s, OCH3); 3.71 (2H, t,
J = 7.6 Hz, CH2); 2.67 (2H, t, J = 7.6 Hz, CH2); 13C-NMR: δ 164.68(C), 151.69(C), 149.88(C), 144.17
(C), 137.63(C), 132.77(CH), 130.23(CH), 128.19(CH), 127.61(CH), 124.52(C), 124.46(C), 124.09(C),
105.63(CH), 60.88(OCH3), 60.83(OCH3), 56.19(OCH3), 47.09 (CH2), 42.58(CH2), 18.99(CH2).
1-(2-Bromobenzyl)-3,4-dihydro-6,7-methylenedioxyisoquinoline (9c). In a similar manner, 9c was
obtained in 42.1% yield from ethanol as a pale yellow solid; m.p. 122-123 °C (Lit. [16] m.p. 121-123
°C); 1H-NMR: δ 7.52 (1H, dd, J = 7.8, 1.0 Hz, Ar-H); 7.22-7.12 (2H, m, Ar-H); 7.06- 6.98 (1H, m, Ar-
H); 6.89 (1H, s, Ar-H); 6.61 (1H, s, Ar-H); 5.86 (2H, s, OCH2O); 4.09 (2H, s, Ar-CH2); 3.65 (2H, t, J
= 7.6 Hz, CH2); 2.60 (2H, t, J = 7.6 Hz, CH2); 13C-NMR: δ 164.65(C), 149.08(C), 146.44(C),
137.55(C), 133.38(C), 132.79 (CH), 130.30(CH), 128.14(CH), 127.50(CH), 124.79(C), 122.77(C),
107.98(CH), 106.02(CH), 101.31(CH2), 47.09(CH2), 42.55(CH2), 26.33(CH2).
1-(2-Bromophenyl)-5,6-dihydro-8,9-dimethoxypyrrolo[2,1-a]isoquinoline-2,3-dione (10a). Oxalyl
chloride (0.2 mL) was added dropwise to a stirred solution of 9a (359 mg, 1 mmol), triethylamine (0.3
mL) in chloroform (10 mL) at room temperature. Stirring was continued for 3 h. Chloroform (20 mL)
was added and the chloroform layer was washed with 5% hydrochloric acid (4 × 50 mL), water (50
mL), then dried over anhydrous sodium sulfate. Removal of the solvent under vacuum gave a residue
which was recrystallized from ethanol to give 10a as red prisms (247.8 mg, 60.0%); m.p. 195-196 °C.
(lit. [6] m.p. 176-178 °C); UV λmax (MeOH) nm (log ε): 203 (4.36), 226sh (4.12), 262 (3.76), 322

Molecules 2009, 14
922
(3.65). IR (CH2Cl2-film) νmax cm-1: 2937, 2843, 1744, 1699, 1594, 1575, 1515, 1472, 1428, 1398,
1337, 1312, 1291, 1270, 1225, 1187, 1101, 1034, 987, 865, 798, 735, 683; 1H-NMR: δ 7.70 (1H, dd, J
= 8.0, 0.9 Hz, Ar-H); 7.44-7.37 (1H, m, Ar-H); 7.34-7.29 (1H, m, Ar-H); 7.29-7.22 (1H, m, Ar-H);
6.77 (1H, s, Ar-H); 6.66 (1H, s, Ar-H); 3.95 (3H, s, OCH3); 3.89 (2H, t, J = 6.3 Hz, CH2); 3.29 (3H, s,
13
OCH3); 3.10 (2H, t, J = 6.3 Hz, CH2); C-NMR: δ 181.59(C), 158.50(C), 158.35(C), 153.80(C),
148.14(C), 133.17(CH), 133.09(C), 132.83(CH), 132.41(C), 129.96(CH), 128.06(CH), 125.82(C),
116.68(C), 111.29(CH), 107.80(C), 56.27(OCH3), 55.17(OCH3), 36.37(CH2), 28.37(CH2). HRMS
(ESI-TOF) calcd for C20H16BrNO4 ([M+H+]) = 414.0335, Found 414.0438.
1-(2-Bromophenyl)-5,6-dihydro-7,8,9-trimethoxypyrrolo[2,1-a]isoquinoline-2,3-dione (10b). In a
similar manner, 10b was obtained as a deep red solid in 68.2% yield after chromatography over
alumina using dichloromethane as eluent; m.p. 69-70 °C; UV (MeOH) λ max nm (log ε): 203 (4.66),
226sh (4.38), 258 (3.95), 332 (3.93); IR (CH2Cl2-film) νmax cm-1: 2939, 2837, 1746, 1702, 1592, 1576,
1467, 1425, 1397, 1342, 1298, 1248, 1182, 1109, 1024, 986, 939, 914, 845, 752; 1H-NMR: δ 7.71 (1H,
dd, J = 8.0, 0.9 Hz, Ar-H); 7.44-7.35 (1H, m, Ar-H); 7.32-7.23 (2H, m, Ar-H); 6.53 (1H, s, Ar-H); 3.94
(3H, s, OCH3); 3.88 (3H, s, OCH3); 3.93-3.73 (2H, m, CH2); 3.27 (3H, s, OCH3); 3.20-3.00 (2H, m,
CH2); 13C-NMR: δ 182.05(C), 158.07(C), 152.24(C), 150.56(C), 147.02(C), 133.21(CH), 132.70(CH),
132.25(C), 130.03(CH), 128.08(CH), 125.77(C), 125.48(C), 119.38(C), 108.64(C), 108.53(CH),
105.68(C), 61.12(OCH3), 61.08(OCH3), 55.21(OCH3), 36.19(CH2), 21.67(CH2). HRMS (ESI-TOF)
calcd for C21H18BrNO5 ([M+H+]) = 444.0441, Found 444.0519.
1-(2-Bromophenyl)-5,6-dihydro-8,9-methylenedioxypyrrolo[2,1-a]isoquinoline-2,3-dione (10c). In a
similar manner, 10c was obtained in 47.7% yield from ethanol as a deep red prisms; m.p. 226-227 °C;
UV (MeOH) λ max nm (log ε): 203 (4.64), 236sh (4.18), 261sh (3.88), 284 (3.77), 320 (3.67), 388
(3.64); IR (CH2Cl2-film) νmax cm-1: 3056, 2906, 1744, 1698, 1608, 1568, 1505, 1467, 1403, 1378,
1
1338, 1316, 1286, 1249, 1181, 1036, 938, 868, 748, 736; H-NMR: δ 7.71-7.66 (1H, m, Ar-H); 7.42-
7.36 (1H, m, Ar-H); 7.31-7.23 (2H, m, Ar-H); 6.79 (1H, s, Ar-H); 6.56 (1H, s, Ar-H); 6.00 (2H, AB q,
13
J = 1.1 Hz, OCH2O); 3.94-3.77 (2H, m, CH2); 3.07 (2H, t, J = 6.3 Hz, CH2); C-NMR: δ 181.94(C),
158.10(C), 157.94(C), 152.47(C), 147.37(C), 135.17(C), 133.43(CH), 132.43(CH), 131.68(C),
130.13(CH), 128.14(CH), 125.35(C), 118.23(C), 109.28(CH), 108.50(CH), 108.23(C), 102.25(CH2),
36.20(CH2), 29.24(CH2). HRMS (ESI-TOF) calcd for C19H12BrNO4 ([M+H+]) = 398.0022, Found
397.9895.
Telisatin A (1). A solution of 1,1′-azobis(cyclohexanecarbonitrile) (245.0 mg, 1.0 mmol) and
tributyltin hydride (1.2 g, 4.0 mmol) in toluene (20 mL) was added dropwise in four equal portions
over 3 h to a refluxing solution of 10a (413.0 mg, 1.0 mmol) in toluene (20 mL) and the resulting
mixture was then refluxed for another 8 h. The solvent was then removed under vacuum and the
residue was dissolved in acetonitrile (40 mL) and washed with hexane (2 × 30 mL), then dried over
anhydrous sodium sulfate. Removal of the solvent gave a brown viscous oil (0.4 g) which was
recrystallized with ethanol to give telisatin A (1) as red prisms (109.9 mg, 33.0%); m.p. 234-235 °C
(Lit. [1] m.p. 238-239 °C); UV (MeOH) λ max nm (log ε): 207 (4.03), 257 (4.26), 284sh (3.60), 322

Molecules 2009, 14
923
(3.70), 336 (3.80), 352sh (3.56); IR (CH2Cl2-film) νmax cm-1: 2925, 1748, 1701, 1605, 1584, 1531,
1462, 1423, 1386, 1306, 1261, 1195, 1149, 1131, 1112, 1037, 969, 924, 802, 759. 1H-NMR δ: 9.41
(1H, br d, J = 8.5 Hz, H−11); 8.63 (1H, dd, J = 8.0, 1.5 Hz, H−8); 7.67-7.60 (1H, m, H−9); 7.54-7.46
(1H, m, H−10); 7.17 (1H, s, H−3); 4.10 (3H, s, OCH3); 3.97 (2H, t, J = 6.5 Hz, CH2); 3.95 (3H, s,
13
OCH3); 3.35 (2H, t, J = 6.5 Hz, CH2); C-NMR: δ 179.98(C), 160.34(C), 157.15(C), 153.36(C),
146.65(C), 130.75(C), 129.35(C), 129.21(CH), 128.33(CH), 127.56(C), 125.87(C), 125.62(CH),
123.76(CH), 112.29(CH), 112.18(C), 103.17(C), 59.99(OCH3), 56.62(OCH3), 36.53(CH2), 27.68
(CH2). HRMS (ESI-TOF) calcd for C20H15NO4 ([M+H+]) = 334.1074, Found 334.1125.
Telisatin B (2). In a similar manner, telisatin B (2) was obtained as deep red prisms (30.0%) from
ethanol; m.p. 218-219 °C (Lit.[1] m.p. 221-222 °C); UV (MeOH) λ max nm (log ε): 203 (4.33), 223sh
(4.26), 257 (4.59), 318sh (3.99), 329 (4.07); IR (CH2Cl2-film) νmax cm-1: 2942, 2864, 1749, 1716,
1702, 1619, 1607, 1579, 1527, 1515, 1452, 1406, 1389, 1323, 1146, 1125, 1071, 1033, 973, 814, 757;
1H-NMR: δ 9.37 (1H, br d, J = 8.5 Hz, H−11), 8.60 (1H, dd, J = 8.0, 1.3 Hz, H−8), 7.64-7.56 (1H, m,
H−9), 7.55-7.45 (1H, m, H−10), 4.14 (3H, s, OCH3), 4.03 (3H, s, OCH3), 4.01 (3H, s, OCH3), 3.91
(2H, t, J = 6.5 Hz, CH2), 3.33 (2H, t, J = 6.5 Hz, CH2); 13C-NMR: δ 180.69(C), 159.86(C), 152.58(C),
152.16(C), 152.03(C), 150.16(C), 128.71(CH), 127.53(CH), 126.63(C), 126.38(C), 126.11(C),
125.78(CH), 123.66(CH), 121.18(C), 114.14(C), 104.17(C), 61.47(OCH3), 61.30(OCH3), 60.48
(OCH3), 36.14(CH2), 21.21(CH2); HRMS (ESI-TOF) calcd for C21H17NO5 ([M+H+]) = 364.1179,
Found 364.1231.
Lettowianthine (3). In a similar manner, lettowianthine (3) was obtained as red prisms (34.0%); m.p.
294-295 °C (dec.) (Lit. [2] m.p. 314-317 °C (dec.); Lit.[4] m.p. 265-267 °C); UV (MeOH) λ max nm
(log ε): 203 (4.37), 212sh (4.29), 247sh (4.07), 257sh (4.04), 287 (3.64), 335 (3.51), 353 (3.28). IR
(CH2Cl2-film) νmax cm-1: 2923, 2093, 1737, 1695, 1622, 1610, 1581, 1530, 1506, 1450, 1417, 1301,
1
1253, 1222, 1176, 1151, 1122, 1050, 927, 867, 749; H-NMR: δ 8.80 (1H, br d, J = 8.6 Hz, H−11),
8.55 (1H, br d, J = 7.6 Hz, H−8), 7.61 (1H, t, J = 6.9 Hz, H−9), 7.48 (1H, t, J = 7.2 Hz, H−10), 7.09
(1H, s, H−3), 6.35 (2H, s, OCH2O), 3.93 (2H, t, J = 6.2 Hz, CH2), 3.29 (2H, t, J = 6.2 Hz, CH2); 13C-
NMR δ: 179.92(C), 160.33(C), 153.68(C), 151.55(C), 143.08(C), 129.61(C), 129.33(CH), 127.62
(CH), 126.83(C), 125.35(CH), 124.45(C), 123.60(CH), 119.90(C), 112.46(C), 109.23(CH), 103.10
(C), 102.35(CH2), 36.66(CH2), 27.51(CH2); HRMS (ESI-TOF) calcd for C19H11NO4 ([M+H+]) =
318.0761, Found 318.0666.
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Sample Availability: All stable products reported in this paper are available from the authors.
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