Synthesis of A/B ring analogs of territrem B and evaluation of their biological activities

1832

Helvetica Chimica Acta Vol. 87 (2004)

Synthesis of A/B Ring Analogs of Territrem B and Evaluation of Their

Biological Activities

by Jinhao Zhao^a)^b), Feng Zhao^a), Yanguang Wang^b), Haibo Li^a), Qijun Zhang^a), Daniel Gue¬nard^c),

Qiufu Ge^d), Erqing Wei^d), Hao Jiang^a), Yihang Wu^a), Lin Wang^e), Hualiang Jiang^f), FranÁoise Gue¬ritte^c),

Xiumei Wu^g), Christopher H. K. Cheng^h), Shoei-Sheng Leeⁱ), and Yu Zhao*^a)

^a) Department of Traditional Chinese Medicine and Natural Drug Research, College of Pharmaceutical

Sciences, Zhejiang University, Hangzhou 310031, China

(phone: 86-571-87217313; fax: 86-571-85270026; e-mail: dryuzhao@zju.edu.cn)

^b) Department of Chemistry, Zhejiang University, Hangzhou 310027, China

^c) Institut de Chimie des Substances Naturelles, CNRS, Avenue de la Terrasse, F-91198 Gif-sur-Yvette, France

^d) College of Medicine, Zhejiang University, Hangzhou 310031, China

^e) School of Pharmacy, Dali College, Dali 671000, China

^f) Shanghai Institute of Material Medica, Chinese Academy of Sciences, Shanghai 200031, China

^g) Zhejiang Hisun Naturelite Pharmaceutical R&D Co., Ltd. 19-G, Huazhe Plaza, Hangzhou 310006, China

^h) Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China

ⁱ) School of Pharmacy, College of Medicine, National Taiwan University, Taipei 10018, Taiwan, China

Two series of territrem B analogs, i.e., 5 10, containing both the 2-en-1-one-A-ring and the aromatic-E-

ring pharmacophores were designed and synthesized from jujubogenin (4a). The anti-acetylcholinesterase (anti-

AChE), anti-caspase-3, and other biological activities of these territrem-B analogs and their intermediates were

assessed. Compound 9b, 22a, and 24f were shown to be weak inhibitors of AChE. None of the synthesized

compounds exhibited significant inhibitory activity on caspase-3. On the other hand, compounds 22e, 24a, 7b,

and 8a showed mild cytotoxicity on cultured KB cells, with IC₅₀values of 2.0, 3.5, 6.5, and 14 mm, respectively. In

addition, compounds 23b and 5f were active against injury arising from oxygen-glucose deprivation.

Introduction. Diseases associated with an aging population are on the rise and

becoming a serious issue around the world. Alzheimer×s disease (AD), a major health

problem of many old people, is a disorder associated with progressive degeneration of

memory and cognition functions. One of the strategies to treat this disease is the

employment of acetylcholinesterase (AChE) inhibitors, a therapeutic approach based

on the cholinergic deficiency hypothesis of AD [1][2]. This hypothesis rationalizes that

the loss of acetylcholine (ACh) in the brain is one of the main causes of AD [2].

Consequently, inhibition of AChE has become an important treatment regimen

because inhibiting the removal of ACh could improve the ACh level in the brain [3].

Arisugacin A (1) and B (2), and territrem B (3), which were isolated from the

culture broth of Penicillium sp. FO-4259 and Aspergillus terreus 23-1, respectively, are

members of the meroterpenoid family [4]. They show potent inhibitory activities

against AChE with IC₅₀values in the range of 1 to 26 nm. Moreover, their inhibitory

mechanism is different from the other known AChE inhibitors [5]. Peng et al. [6]

proposed that the 2-en-1-one moiety in these compounds is essential for their inhibitory

activities against AChE because modification of the A ring in territrem B resulted in a

large reduction or even complete abolition of the inhibitory potency. Zhao et al. [7] had

Helvetica Chimica Acta Vol. 87 (2004)

1833

prepared A/B-ring analogs of territrem B starting from the triterpenoid jujubogenin

(4a) and found that they possess inhibitory activity against AChE with an IC₅₀value of

10 mm. In addition, we proposed that the aromatic moiety in the E ring present in

territrem B and arisugacins might be another pharmacophore apart from the 2-en-1-

one moiety in the A ring. Therefore, attempts to combine the two potential

pharmacophores into one molecule would constitute an extension of the structure-

activity-relationship (SAR) investigation of these AChE inhibitors.

According to the prediction of a molecular-modelling study, Chen et al. [5] showed

that the pyran and the terpenoid moieties of territrem B (3) bind to AChE by

occupying a large portion of the AChE substrate channel (the gorge), making contacts

1834

Helvetica Chimica Acta Vol. 87 (2004)

with 23 amino acids to block the access of ACh to the bottom of the long narrow gorge,

at which the catalytic center of AChE is buried [5]. As a result of this binding, the

substrate ACh is prevented from being hydrolyzed. To choke the entrance of the gorge,

the molecule must adopt a suitable spatial length. This −choking hypothesis× enspired us

to design a series of molecules with different lengths as compared to the leads, e.g., by

preparing a molecule with an eight-bond linkage between C(1) of the 1-one function

and C(1') of the aromatic ring (see 5 7), and a corresponding ten-bond-linkage

molecule (see 8 10 in Fig. 1). To demonstrate the relationship between the length and

bioactivity, the length of the C(1) ¥¥¥ C(1') distance in compounds 5 10 (named

Distance A, abbreviated as Da) was also compared with that of territrem B (3) by

means of SYBYL calculations (Table 1).

Table 1. Comparison of Distances within Territrem B (3) and 5 10 by SYBYL Calculations. See also Fig. 1.

Eight-bond-linkage compounds

Ten-bond-linkage compounds

territrem B (3)

5

6

7

8

9

10

Da^a) [ä]

Db^b) [ä]

Dc^c) [ä]

Dd^d) [ä]

11.809

4.910

6.994

12.017

7.443

6.156

12.885

7.441

6.345

11.965

7.409

6.399

14.861

9.014

9.160

15.673

9.669

8.419

8.575

14.783

9.056

8.874

9.670

11.373

10.349

11.102

10.589

10.194

^a) Da sum of the length of bold bonds between C(1) and C(1'). ^b) Db spatial distance between the two

CO of 5 10 and territrem B (3). ^c) Dc spatial distance between the O-atom at C(1) and the X-atom of 5

10, and the distance between the O-atom at C(1) and C(9) in territrem B (3). ^d) Dd spatial distance between

the geometric center of the 2-en-1-one moiety and that of the aromatic ring in territrem B (3) and 5 10.

Furthermore, it is conceivable that the two carbonyl groups present in territrem B

(3) might bind jointly with AChE in a cooperative manner to block the substrate

channel. Therefore, the spatial distance between its two CO groups (named

Distance B, abbreviated as Db) might also be important; thus, the Db of 3 and 5 10

were also compared (Table 1). Based on the principle of bioisosterism, the aromatic

thioesters and aromatic amides were synthesized. The two other spatial-distance factors

Dc and Dd (see Fig. 1), i.e., the spatial distances between C(1) O and the X-atom of

5 10 (Dc) and between the geometrical center of the 2-en-1-one pharmacophore and

the geometrical center of the aromatic ring of 5 10 (Dd), respectively, were also

calculated (Table 1).

Since the supply of territrem B (3) is limited due to the low yield from

fermentation, we started our semi-synthetic preparative work from the naturally

abundant triterpenoid jujubogenin (4a), which was derived from jujubogenin glyco-

sides 4b isolated from the leaves of Zizyphus jujuba Var. spinosa (Bunge) hu. With the

view of looking into other potential biological activities related to the prevention and

treatment of AD, these synthetic compounds were also tested for caspase-3 inhibition

and protection against oxygen-glucose deprivation (OGD)-induced injury of rat

primary neurons.

The synthesis and the evaluation of the biological activities of the compounds 5 10

are reported herein, together with a comparison of their spatial parameters Da to Dd.

Helvetica Chimica Acta Vol. 87 (2004)

1835

Fig. 1. Eight-bond- and ten-bond-linked potential inhibitors 5 7 and 8 10 of acetylcholinesterase as compared

to territrem B (3). See also Table 1.

Results and Discussions.

Synthesis. The BuOH extract from the leaves of

Zizyphus jujuba Var. spinosa (Bunge) hu, containing jujubogenin glycosides 4b, was

treated under O₂with NaOBu at 908 to give jujubogenin (4a) [7]. After acidic

hydrolysis of pure jujubogenin 4a ( ! 11/12) followed by mesylation, a mixture 13/14

of (20E)- and (20Z)-3-[(methylsulfonyl)oxy]-ebelin lactone [7] was obtained

(Scheme 1). The crude mixture was ozonized and reduced with Me₂S [8] to afford

the aldehydes 15 17 with yields of 44, 8, and 1%, respectively. However, when the

1836

Helvetica Chimica Acta Vol. 87 (2004)

Scheme 1

a) HCl/EtOH/H₂O 1 :3 :3, 808, 5 h. b) MsCl, pyridine, 08, 10 h. c) 1. O₃, MeOH/CH₂Cl₂1:1, À 788, 1 h; 2. Me₂S,

À 108, 1 h; 08, 1 h; r.t., 1 h.

ozonide was reduced with Zn powder or with thiourea, the yields of aldehydes were

unsatisfactory.

Oxidation of aldehyde 15 with N-bromosuccinimide (NBS) under irradiation [9]

gave the corresponding acyl bromide 18, which was treated directly with substituted

phenols, thiophenols, or arylamines to afford the corresponding esters 19, thioesters 20,

or amides 21 in 22.7 75.2% yield (Scheme 2). Compounds 19 21 were treated with

Li₂CO₃in refluxing N,N-dimethylacetamide (DMAC) [10] for 30 min to afford the 2-

ene derivatives 22 24 in 28.3 83.9% yield. During the oxidation of 22 (R¹ R³ H,

R² H, 4'-Cl or 4'-NO₂) by CrO₃in AcOH at 808, the yield of the corresponding target

compounds 5 was not satisfactory (18 29.4%) due to formation of the 1-en-3-one by-

products 25 by an unexpected radical rearrangement reaction. Furthermore, when the

aromatic ring was substituted by an electron-donating group such as MeO or Me, it was

difficult to obtain the expected enone products 5 7, since the electron-donating aryl

part was fragile under these oxidative conditions.

Alternatively, oxidation of the 2-ene compounds 22 24 with the mild oxidative

reagent N-bromosuccinimide (NBS) in 1,4-dioxane in the presence of CaCO₃[11]

furnished the target enone compounds 5 7 directly in 20 37% yield as well as the 1-

bromo products 26 28 (Scheme 3). The latter could be hydrolyzed to the enol

derivatives, which were subsequently oxidized with pyridinium chlorochromate (PCC)

to give enones 5 7 smoothly. As a result, the total yield of 5 7 was higher than that

obtained from oxidation by CrO₃. Moreover, when the aromatic ring was substituted by

an electron-donating group such as one or more MeO, the corresponding 2-en-1-one

derivatives of 5 7 could also be obtained smoothly in good yield. Therefore, the

preparative route of the 2-en-1-one moiety in 5 7 from 2-ene compounds 22 24 by

oxidation with NBS is entirely feasible and, in fact, favorable.

Helvetica Chimica Acta Vol. 87 (2004)

Scheme 2^a)

1837

a) NBS, CCl₄, hv, reflux, 5 min. b) ArOH, ArSH, or ArNH₂, Et₃N, r.t., 1 h. c) Li₂CO₃, DMAC, reflux, 0.5 h. d)

CrO₃, AcOH, 808, 1 h.

^a) For R¹, R², and R³, see names in the Exper. Part.

Scheme 3^a)

a) CaCO₃, NBS, dioxane, H₂O, 508, 6 h, hv. b) CaCO₃, H₂O, dioxane, reflux, 5 h. c) PCC, CH₂Cl₂, reflux, 6 h.

^a) For R¹, R², and R³, see names in the Exper. Part.

By a similar method, the other series of territrem B analogs 8 10 and their

intermediates 30 38 could also be prepared from the a,b-unsaturated aldehyde 16 via

29 (Scheme 4).

Evaluation of Biological Activities. All the synthesized compounds were evaluated

for their AChE inhibitory activities according to the method of Ellman et al. [12].

However, only compounds 9b and 24f showed some activity against AChE with 70%

inhibition at 10^À4m. Thus, probably some other factors apart from the 2-en-1-one and

1838

Helvetica Chimica Acta Vol. 87 (2004)

Scheme 4^a)

a) NBS, CCl₄, hv, reflux, 5 min. b) ArOH, ArSH, or ArNH₂, Et₃N, r.t., 1 h. c) Li₂CO₃, DMAC, reflux, 0.5 h. d)

CaCO₃, NBS, dioxane, H₂O, 508, 6 h, hv. e) CaCO₃, H₂O, dioxane, reflux, 5 h. f) PCC, CH₂Cl₂, reflux, 6 h.

^a) For R¹, R², and R³, see names in the Exper. Part.

aromatic-E-ring pharmacophores contribute to the anti-AChE activity. The absence of

the 5a-OH and 9a-OH groups in the territrem-B analogs might also affect their AChE-

inhibition activity. Furthermore, it could be seen that the C(2)C(3) moiety and the

aliphatic E ring might also affect the anti-AChE activity. On the other hand, increasing

the number of bonds between the two CO groups did not improve the enzyme-

inhibition activity. The superposition of compounds 5a h, 6a c, 7a c, 8a d, 9a c,

and 10a with territrem B (3), based on their C-atoms in the A and B rings, as calculated

by the SYBYL program, showed that the aromatic E ring in these derivatives has

apparently deviated from that in territrem B (Figs. 2 and 3). Therefore, subsequent

Helvetica Chimica Acta Vol. 87 (2004)

1839

Fig. 2. Superposition of compounds 5a h, 6a c, 7a c, and territrem B (3; in red), based on C-atoms in the A

and B rings, obtained by SYBYL calculations

Fig. 3. Superposition of compounds 8a d, 9a c, 10a, and territrem B (3; in red), based on C-atoms in the A and

B rings, obtained by SYBYL calculations

modifications would focus on the synthesis of further analogs possessing a planar angle

identical to that of territrem B, and with the enone and the aromatic rings combined in

the same molecule with a suitable spatial length.

Within the caspase family, caspase-3 plays a critical role in neuronal-cell death

during development and after neuronal injury [13], and has previously been shown to

be relevant to memory loss [14]. However, results related to the investigation of

1840

Helvetica Chimica Acta Vol. 87 (2004)

territrem-B analogs on this enzyme model are absent in the pertinent literature.

Therefore, the two series of compounds were tested for caspase-3 inhibitory activity.

However, the results showed rather weak inhibitory activities of these synthetic

compounds (Table 2).

Table 2. Inhibition [%] of Caspase-3 by Selected Compounds at 20-mm Concentration

5a

5b6b22a

22c

22g

22h

33d

34c

35b

Inhibition

0

2.0

3.5

2.7

4.2

5.4

1.6

1.8

3.3

2.4

Although, to the best of our knowledge, the cytotoxicity of territrem B (3) and its

analogs is not described in the literature, enones quite often act as cytotoxic

pharmacophores, and many natural products possess cytotoxicity against various

tumor cell lines [15][16]. Since the two series of synthetic analogs contain a common 2-

en-1-one moiety and were derived from natural products, it is reasonable to investigate

the cytotoxicity of these compounds as well. The commonly used cultured KB cell line

was employed for this screening [17]. In addition to compounds 7b and 8a showing

cytotoxicity to KB cells at 6.5 and 14.0 mm, respectively, two 2-ene intermediates,

compounds 22e and 24a, also exhibited cytotoxicity at 2.0 and 3.5 mm, respectively

(Table 3). This might be due to the presence of the g-lactone structure in these

molecules.

Table 3. Cytotoxicity of Compounds 8a, 7b, 24a, and 22e against KB Cells

8a

7b24a

22e

Inhibition [%] at 10 mm^a)

IC₅₀[mm]^a)

68 Æ 11

50 Æ 8

56 Æ 13

56 Æ 6

14.0 Æ 1.3

6.5 Æ 1.8

3.5 Æ 0.4

2.0 Æ 0.3

^a) Values are expressed as mean Æ standard deviation, n 3.

It is known that the risk of AD is significantly increased after acute events of

cerebrovascular diseases such as stroke or transient ischemic attacks. Furthermore,

organic damage of the brain caused by OGD may also lead to dementia [18]. We have,

therefore, examined the potential neuroprotective effect of these synthetic analogs on

OGD-induced injury on rat primary neurons. The results showed that compounds 23b

and 5f exhibit protective activity on rat hippocampal cell against OGD injury

(Table 4).

Conclusions. Two series of triterpenoid derivatives, 5 7 and 8 10, were prepared

starting from jujubogenin (4a). Few synthetic analogs exhibited promising inhibitory

activity towards AChE. This implies that some other structural factors influencing the

inhibition ratio among the territrem-B analogs remain to be elucidated. Based on the

results obtained in the present study, further preparation and investigation of territrem-

B analogs possessing both 5a-OH and 9a-OH groups together with the 2-en-1-one

moiety and the appropriate spatial position of the aromatic E ring will be carried out in

our further work. The assumption that these synthetic compounds might be cytotoxic

was justified to some extent by the finding that compounds 22e, 24a, 7b, and 8a show

Helvetica Chimica Acta Vol. 87 (2004)

1841

Table 4. Protection of Rat Primary Neurons from OGD-Induced Injury

c [mm]

OD₄₉₀[nm]^a)

OGD Control

Compound 23b

0.094 Æ 0.002

0.1

1.0

10.0

0.1

1.0

10.0

0.115 Æ 0.009^b)

0.114 Æ 0.005^b)

0.123 Æ 0.018^b)

0.116 Æ 0.004^b)

0.132 Æ 0.008^b)

0.127 Æ 0.004^b)

Compound 5f

^a) Values are expressed as mean Æ standard deviation, n 3. ^b)P < 0.05 vs. OGD control.

some cytotoxicity on cultured KB cells. In addition, compounds 23b and 5f exhibited

protective activity against OGD-induced injury of rat primary neurons, indicating that

further investigations of these compounds on the prevention and treatment of the

complications of cerebrovascular diseases are highly warranted.

This work was financially supported in part by China-France PRA BT01-02 and Zhejiang University. We

are grateful to Dr. Xiaojiang Hao (KIB, Chinese Academy of Sciences) for helpful suggestions. One of the

authors (Y. Zhao) would also like to express his thanks to the Chinese Ministry of Education as well as to Mr.

Ka-shing Li for the −Cheung Kong Scholar Chair Professorship× at Zhejiang University.

Experimental Part

1. General. TLC: silica gel 60 GF-254 plates. CC column chromatography, FC flash CC. NMR Spectra:

Bruker Advance at 400 MHz, Bruker Advance DMX at 500 (¹H) and 100 MHz (¹³C); chemical shift d in ppm

with Me₄Si as an internal standard, coupling constants J in Hz. EI-MS: HP5898B. ESI-MS: Bruker Esquire

3000 . FAB-MS: VG Autospec-3000. Molecular calculations were carried out with the SYBYL program

version 6.1, on a Silicon-Graphics Indigo (SGI) workstation.

2. Jujubogenin (4a): General Method. Jujubogenin (4a) was prepared from the jujubogenin glycoside 4b

isolated from the leaves of Zizyphus jujuba Var. spinosa (Bunge) hu according to [7].

3. Aldehydes 15 17: General Method. 3.1. The crude mixture 13/14 of (20E)- and (20Z)-3-O-

(methylsulfonyl)ebelin lactones¹) was prepared according to [7] by hydrolysis of jujubogenin (4a; 5.0 g,

10.6 mmol) followed by mesylation of the crude ebelin lactones 11 and 12.

3.2. Ozonolysis of the Crude Mixture 13/14. The colorless soln. of the crude mixture 13/14 in CH₂Cl₂(10 ml)

and MeOH (40 ml) was cooled to À 788 in a liq. N₂/EtOH bath, and O₃containing O₂was introduced (0.1 m³/h)

until no starting material could be detected by TLC. Me₂S (3.5 ml) was added dropwise within 1 min at À 708,

and then the temp. was increased to À 108. Stirring was continued for 1 h at À 108 and then for 1 h at 08. AcOH

(0.5 ml) was added, and the reaction was continued for 1 h at r.t. After evaporation, the residue was taken up in

CH₂Cl₂(50 ml) and H₂O (30 ml), the aq. layer extracted with CH₂Cl₂(3 Â 50 ml), the combined org. layer

washed with 10% aq. Na₂CO₃soln. and H₂O, dried (MgSO₄), and evaporated, and the white solid subjected to

CC (SiO₂, hexane/AcOEt 2 :1): 3-O-(methylsulfonyl)-20-secoebelin-20-al lactone¹) (15; 2.1 g, 44% from 4a),

(20E)-3-O-(methylsulfonyl)-22-secoebelin-22-al lactone¹) (16; 0.4 g, 8% from 4a), and (20Z)-3-O-(methylsul-

fonyl)-22-secoebelin-22-al lactone¹) (17; 0.05 g, 1% from 4a). ¹H-NMR of 15 17: in accordance with those

reported in [19].

4. 3-O-(Methylsulfonyl)-20-secoebelin-20-oic Acid Lactone 20-Aryl Esters ((1'S,2'S,4'aR,4'bR,7'S,

8'aR,10'aR)-Tetradecahydro-4'b,8',8',10'a-tetramethyl-7'-[(methylsulfonyl)oxy]-5-oxospiro[furan-3(2H),1'(2'H)-

phenanthrene]-2'-carboxylic Acid Aryl Esters) 19, 3-O-(Methylsulfonyl)-20-secoebelin-20-thioic Acid Lactone

20-S-Aryl Esters ((1'S,2'S,4'aR,4'bR,7'S,8'aR,10'aR)-Tetradecahydro-4'b,8',8',10'a-tetramethyl-7'-[(methylsul-

1

)

Ebelin lactone (1'S,2'R,4'aR,4'bR,7'S,8'aR,10'aR)-2'-[(1E,3E)-2,6-dimethylhepta-1,3,5-trienyl]dodecahy-

dro-7'-hydroxy-4'b,8',8',10'a-tetramethylspiro[furan-3(2H),1'(2'H)-phenanthren]-5(4H)-one.

1842

Helvetica Chimica Acta Vol. 87 (2004)

fonyl)oxy]-5-oxospiro[furan-3(2H),1'(2'H)-phenanthrene]-2'-carbothioic Acid S-Aryl Esters) 20, and N-Aryl-3-

O-(methylsulfonyl)-20-secoebelin-20-amide Lactones ((1'S,2'S,4'aR,4'bR,7'S,8'aR,10'aR)-N-Aryl-tetradecahy-

dro-4'b,8',8',10'a-tetramethyl-7'-[(methylsulfonyl)oxy]-5-oxospiro[furan-3(2H),1'(2'H)-phenanthrene]-2'car-

boxamides) 21: General Method. To a soln. of 15 (132 mg, 0.3 mmol) in CCl₄(10 ml), NBS (62.3 mg, 0.35 mmol)

was added under N₂. The flask was irradiated with a 100-W flood lamp, and spontaneous reflux was allowed to

continue for 5 min. Then the mixture containing acyl bromide 18 was cooled to 08 and treated directly with the

substituted phenol, thiophenol, or aniline (0.3 mmol each) in the presence of Et₃N (0.3 mmol). Stirring was

continued for 1 h at r.t. After evaporation, the residue was diluted with CH₂Cl₂(10 ml), the soln. washed with

H₂O, dried (MgSO₄), and evaporated, and the crude product subjected to CC (SiO₂, hexane/AcOEt 3 :1): 19,

20, or 21, resp.

20-Phenyl Ester 19a: Yield 92 mg (57.6%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.53. ¹H-NMR (400 MHz,

CDCl₃): 0.88 (s, Me(22)); 0.92 (s, Me(19)); 1.04 (s, Me(21)); 1.07 (s, Me(18)); 2.65 (d, J 18.7, 1 HÀC(15));

2.68 (d, J 18.7, 1 HÀC(15)); 2.96 (m, H ÀC(13)); 3.03 (s, MeSO₂); 4.34 (dd, J 11.8, 4.9, HÀC(3)); 4.43

(d, J 10.2, 1 HÀC(17)); 4.69 (d, J 10.3, 1 HÀC(17)); 7.04 (dd, J 1.2, 8.2, HÀC(2'), HÀC(6')); 7.23

(m, HÀC(4')); 7.37 (m, HÀC(3'), HÀC(5')). ¹³C-NMR (100 MHz, CDCl₃): 16.0 (C(19)); 16.2 (C(21)); 17.8

(C(18)); 17.8 (C(6)); 19.4 (C(11)); 25.1 (C(12)); 26.1 (C(2)); 29.7 (C(22)); 33.4 (C(15)); 34.7 (C(7)); 36.8

(C(10)); 38.1 (C(1)); 38.7 (MeSO₂); 40.5 (C(4)); 46.2 (C(9)); 50.0 (C(14)); 52.2 (C(13)); 55.2 (C(5)); 69.6

(C(17)); 89.5 (C(3)); 121.4 (C(2'), C(6')); 126.2 (C(4')); 129.5 (C(3'), C(5')); 150.2 (C(1')); 172.3 (C(20)); 176.0

(C(16)). EI-MS: 532 (2, M ), 436 (6), 393 (29), 343 (37), 315 (100), 135 (67), 121 (73), 107 (52), 94 (88).

20-(4-Chlorophenyl) Ester 19b: Yield 73.2 mg (43.1%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.55.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.91 (s, Me(19)); 1.05 (s, Me(21)); 1.07 (s, Me(18)); 2.60 (d, J

18.6, 1 HÀC(15)); 2.71 (d, J 18.5, 1 HÀC(15)); 2.95 (m, HÀC(13)); 3.03 (s, MeSO₂); 4.34 (dd, J 11.5, 4.8,

HÀC(3)); 4.43 (d, J 10.2, 1 HÀC(17)); 4.66 (d, J 10.2, 1 HÀC(17)); 6.99 (br. d, J 8.4, HÀC(2'),

HÀC(6')); 7.33 (dd, J 8.4, HÀC(3'), HÀC(5')). EI-MS: 531 (3, [M À Cl] ), 485 (2), 450 (17), 435 (3), 407

(7), 343 (8), 315 (20), 108 (100).

20-(2,4-Dichlorophenyl) Ester 19c: Yield 91.1 mg (50.7%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.58.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.92 (s, Me(19)); 1.05 (s, Me(21)); 1.07 (s, Me(18)); 2.60 (d, J

18.8, 1 HÀC(15)); 2.71(d, J 18.7, 1 HÀC(15)); 2.96 (s, MeSO₂); 3.08 (m, HÀC(13)); 4.34 (dd, J 11.7, 4.8,

HÀC(3)); 4.44 (d, J 10.3, 1 HÀC(17)); 4.66 (d, J 10.3, 1 HÀC(17)); 7.05 (d, J 8.4, HÀC(6')); 7.26 (dd, J

8.4, 2.4, HÀC(5')); 7.44 (d, J 2.4, HÀC(3')). EI-MS: 504 ( 4, [M À Me₃SO₃H 1] ), 359 (6), 343 (21), 315

(92), 191 (24), 162 (46), 147 (27), 121 (100).

20-[4-(Methylthio)phenyl] Ester 19d: Yield 129.3 mg (74.6%). Colorless oil. R_f(hexane/AcOEt 1 :1) 0.58.

¹H-NMR (400 MHz, CDCl₃): 0.92 (s, Me(22)); 0.94 (s, Me(19)); 1.05 (s, Me(21)); 1.07 (s, Me(18)); 2.47

(s, MeS); 2.56 (d, J 18.6, 1 HÀC(15)); 2.68 (d, J 18.6, 1 HÀC(15)); 2.95 (m, HÀC(13)); 3.02 (s, MeSO₂);

4.34 (dd, J 11.8, 4.6, HÀC(3)); 4.45 (d, J 10.2, 1 HÀC(17)); 4.67 (d, J 10.2, 1 HÀC(17)); 7.07 (br. d, J

8.8, HÀC(2'), HÀC(6')); 7.25 (br. d, J 8.8, HÀC(3'), HÀC(5')). EI-MS: 482 (40, [M À Me₃SO₃H] ), 439 (4),

407 (7), 343 (2), 315 (13), 140 (100). FAB-MS: 578 (5, M ), 530 (17).

20-(4-Methoxyphenyl) Ester 19e: Yield 60.9 mg (36.1%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.31.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.91 (s, Me(19)); 1.05 (s, Me(21)); 1.07 (s, Me(18)); 2.65 (d, J

18.6, 1 HÀC(15)); 2.68 (d, J 18.5, 1 HÀC(15)); 2.95 (m, HÀC(13)); 3.03 (s, MeSO₂); 3.78 (s, MeO); 4.20

(dd, J 11.8, 4.8, HÀC(3)); 4.44 (d, J 10.2, 1 HÀC(17)); 4.69 (d, J 10.2, 1 HÀC(17)); 6.87 (br. d, J 8.8,

HÀC(3'), HÀC(5')); 6.95 (br. d, J 8.8, HÀC(2'), HÀC(6')). FAB-MS: 564 (9, [M 2] ), 466 (4), 343 (11),

315 (7), 282 (100).

20-(Naphthalen-1-yl) Ester 19f: Yield 128.7 mg (73.7%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.48.

¹H-NMR (400 MHz, CDCl₃): 0.89 (s, Me(22)); 0.95 (s, Me(19)); 1.06 (s, Me(21)); 1.12 (s, Me(18)); 2.72 (d, J

18.7, HÀC(15)); 2.75 (d, J 18.6, HÀC(15)); 3.03 (s, MeSO₂); 3.25 (m, HÀC(13)); 4.35 (dd, J 11.8, 4.7,

HÀC(3)); 4.48 (d, J 10.3, 1 HÀC(17)); 4.77 (d, J 10.1, 1 HÀC(17)); 7.20 (d, J 8.0, HÀC(2')); 7.46

(m, HÀC(5')); 7.52 (m, HÀC(3'), HÀC(4')); 7.75 (m, HÀC(6'), HÀC(7')); 7.88 (m, HÀC(8')). EI-MS: 486 (8,

[M À MeSO₃H] ), 343 (3), 315 (16), 144 (100).

20-(Naphthalen-2-yl) Ester 19g: Yield 39.6 mg (22.7%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.52.

¹H-NMR (400 MHz, CDCl₃): 0.89 (s, Me(22)); 0.93 (s, Me(19)); 1.06 (s, Me(21)); 1.09 (s, Me(18)); 2.72 (d, J

18.7, 1 HÀC(15)); 2.74 (d, J 18.6, 1 HÀC(15)); 3.03 (s, MeSO₂); 3.08 (m, HÀC(13)); 4.35 (dd, J 11.7, 4.7,

HÀC(3)); 4.48 (d, J 10.3, 1 HÀC(17)); 4.74 (d, J 10.1, 1 HÀC(17)); 7.18 (dd, J 2.5, 8.5, 1 H); 7.48

(m, 3 H); 7.80 (m, 3 H). EI-MS: 486 (12, [M À MeSO₃H] ), 443 (10), 343 (7), 315 (27), 144 (100).

20-(4-Nitropheny) Ester 19h: Yield 112.7 mg (65.1%). Colorless oil. R_f(hexane/AcOEt 1 :1) 0.65. ¹H-NMR

(400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.92 (s, Me(19)); 1.05 (s, Me(21)); 1.08 (s, Me(18)); 2.59 (d, J 18.7,

Helvetica Chimica Acta Vol. 87 (2004)

1843

1 HÀC(15)); 2.75 (d, J 18.6, 1 HÀC(15)); 3.03 (s, MeSO₂); 3.05 (m, HÀC(13)); 4.32 (dd, J 11.5, 4.9,

HÀC(3)); 4.45 (d, J 10.2, 1 HÀC(17)); 4.63 (d, J 10.2, 1 HÀC(17)); 7.24 (br. d, J 8.8, HÀC(2'), HÀC(6'));

8.26 (br. d, J 8.8, HÀC(3'), HÀC(5')). EI-MS: 481 (37, [M À MeSO₃H] ), 466 (27), 451 (7), 438 (100), 343

(31), 315 (72).

20-(4-Methylphenyl) Ester 19i: Yield 79.1 mg (48.3%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.30.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.92 (s, Me(19)); 1.05 (s, Me(21)); 1.07 (s, Me(18)); 2.33

(s, MeÀC(4')); 2.65 (d, J 18.7, 1 HÀC(15)); 2.70 (d, J 18.6, 1 HÀC(15)); 2.98 (m, HÀC(13)); 3.03

(s, MeSO₂); 4.33 (dd, J 11.8, 4.9, HÀC(3)); 4.43 (d, J 10.2, 1 HÀC(17)); 4.63 (d, J 10.2, 1 HÀC(17));

6.90 (br. d, J 8.4, HÀC(2'), HÀC(6')); 7.17 (br. d, J 8.4, HÀC(3'), HÀC(5')). EI-MS: 546 (5, M ), 466 (27),

450 (45), 407 (35), 343 (15), 315 (58), 135 (57), 108 (100).

20-([1,1'-Biphenyloxy]-4-yl) Ester 19j: Yield 93.2 mg (51.1%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.56.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.92 (s, Me(19)); 1.06 (s, Me(21)); 1.07 (s, Me(18)); 2.65 (d, J

18.7, 1 HÀC(15)); 2.58 (d, J 18.7, 1 HÀC(15)); 3.05 (m, HÀC(13)); 3.02 (s, MeSO₂); 4.27 (dd, J 11.8, 4.9,

HÀC(3)); 4.37 (d, J 10.2, 1 HÀC(17)); 4.64 (d, J 10.3, 1 HÀC(17)); 7.04 (br. d, J 8.4, HÀC(3'),

HÀC(5')); 7.36 (m, HÀC(4'')); 7.43 (m, HÀC(2'), HÀC(6')); 7.48 (m, 4 H). ¹³C-NMR (100 MHz, CDCl₃):

16.2 (C(19)); 16.4 (C(21)); 18.0 (C(18)); 18.0 (C(6)); 19.6 (C(11)); 25.3 (C(12)); 26.2 (C(2)); 28.3 (C(22)); 33.6

(C(15)); 34.9 (C(7)); 37.0 (C(10)); 38.3 (C(1)); 38.7 (MeSO₂); 40.7 (C(4)); 46.24 (C(9)); 50.3 (C(14)); 52.4

(C(13)); 55.3 (C(5)); 69.8 (C(17)); 89.6 (C(3)); 121.8 (C(3'), C(5')); 127.3 (C(2''), C(6'')); 127.6 (C(4'')); 128.4

(C(2'), C(6')); 128.9 (C(3''), C(5'')); 139.5 (C(1')); 140.4 (C(1'')); 149.7 (C(4')); 1721.9 (C(20)); 175.6 (C(16)).

EI-MS: 608 (1, M ), 512 (37), 497 (6), 469 (37), 343 (5), 315 (31), 170 (100).

20-(3,4,5-Trimethoxyphenyl) Ester 19k: Yield 73.4 mg (40.0%). Colorless oil. R_f(hexane/AcOEt 1 :1) 0.22.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.96 (s, Me(19)); 1.06 (s, Me(21)); 1.13 (s, Me(18)); 2.60 (d, J

18.7, 1 HÀC(15)); 2.67 (d, J 18.6, 1 HÀC(15)); 3.07 (m, HÀC(13)); 3.09 (s, MeSO₂); 3.69 (s, MeO); 3.77

(s, MeOÀC(2'), MeOÀC(6')); 4.31 (dd, J 11.2, 6.4, HÀC(3)); 4.55 (d, J 10.4, 1 HÀC(17)); 4.61 (d, J 10.4,

1 HÀC(17)); 6.44 (br. s, HÀC(2'), HÀC(6')).

20-S-Phenyl Ester 20a: Yield 75.8 mg (46.1%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.68. ¹H-NMR

(400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.90 (s, Me(19)); 1.03 (s, Me(21)); 1.04 (s, Me(18)); 2.64 (br. s, HÀC(15));

3.02 (s, MeSO₂); 3.05 (m, HÀC(13)); 4.32 (dd, J 11.9, 4.6, HÀC(3)); 4.35 (d, J 10.0, 1 HÀC(17)); 4.82

(d, J 10.1, 1 HÀC(17)); 7.38 (m, HÀC(2'), HÀC(6')); 7.42 (m, HÀC(3'), HÀC(5')); 7.45 (m, HÀC(4')).

20-S-(4-Chlorophenyl) Ester 20b: Yield 92.8 mg (53.1%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.76.

¹H-NMR (400 MHz, CDCl₃): 0.85 (s, Me(22)); 0.88 (s, Me(19)); 1.01 (s, Me(21)); 1.03 (s, Me(18)); 2.59 (d, J

18.6, 1 HÀC(15)); 2.62 (d, J 18.6, 1 HÀC(15)); 3.00 (s, MeSO₂); 3.05 (m, HÀC(13)); 4.32 (dd, J 11.9, 4.6,

HÀC(3)); 4.74 (d, J 10.1, 1 HÀC(17)); 4.76 (d, J 10.1, 1 HÀC(17)); 7.20 (br. d, J 8.4, HÀC(2'), HÀC(6'));

7.42 (br. d, J 8.4, HÀC(3'), HÀC(5')). EI-MS: 545 (1, [M À Cl] ), 531 (16), 516 (3), 486 (7), 471 (2), 443 (10),

383 (67), 357 (11), 343 (71), 315 (100).

20-S-(2,6-Dichlorophenyl) Ester 20c: Yield 128.1 mg (69.2%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.72.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.91 (s, Me(19)); 1.03 (s, Me(21)); 1.06 (s, Me(18)); 2.61 (d, J

18.6, 1 HÀC(15)); 2.70 (d, J 18.6, 1 HÀC(15)); 3.02 (s, MeSO₂); 3.09 (m, HÀC(13)); 4.38 (dd, J 11.6, 5.2,

HÀC(3)); 4.38 (d, J 10.1, 1 HÀC(17)); 4.80 (d, J 10.1, 1 HÀC(17)); 7.29 (m, HÀC(4')); 7.42 (br. d, J 8.0,

HÀC(3'), HÀC(5')).

20-S-(4-Methoxyphenyl) Ester 20d: Yield 90.3 mg (52.1%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.58.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.90 (s, Me(19)); 1.03 (s, Me(21)); 1.04 (s, Me(18)); 2.64

(s, 2 HÀC(15)); 3.02 (s, MeSO₂); 3.05 (m, HÀC(13)); 3.81 (s, MeO); 4.28 (m, HÀC(3)); 4.35 (d, J 9.9,

1 HÀC(17)); 4.87 (d, J 9.9, 1 HÀC(17)); 6.87 (br. d, J 8.8, HÀC(3'), HÀC(5')); 7.28 (br. d, J 8.8,

HÀC(2'), HÀC(6')). EI-MS: 578 (0.5, M ), 482 (20), 343 (7), 315 (56).

20-S-(3-Methoxyphenyl) Ester 20e: Yield 46.3 mg (26.7%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.62.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.91 (s, Me(19)); 1.04 (s, Me(21)); 1.06 (s, Me(18)); 2.64

(s, 2 HÀC(15)); 3.03 (s, MeSO₂); 3.06 (m, HÀC(13)); 3.82 (s, MeO); 4.33 (dd, J 11.6, 4.4, HÀC(3)); 4.38

(d, J 10.0, 1 HÀC(17)); 4.82 (d, J 10.0, 1 HÀC(17)); 6.91 (m, HÀC(2')); 6.95 (br. d, J 8.4, HÀC(4'),

HÀC(6')); 7.32 (m, HÀC(5')).

20-S-(2-Methoxyphenyl) Ester 20f: Yield 104.5 mg (60.3%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.65.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.91 (s, Me(19)); 1.03 (s, Me(21)); 1.06 (s, Me(18)); 2.62 (d, J

18.8, 1 HÀC(15)); 2.93 (d, J 18.8, 1 HÀC(15)); 3.02 (s, MeSO₂); 3.06 (m, HÀC(13)); 3.81 (s, MeO); 4.33

(dd, J 11.6, 4.8, HÀC(3)); 4.38 (d, J 10.4, 1 HÀC(17)); 4.87 (d, J 10.4, 1 HÀC(17)); 6.97 (m, HÀC(3'),

HÀC(5')); 7.34 (dd, J 8.0, 1.6, HÀC(6')); 7.42 (ddd, J 1.6, 7.6, 8.0, HÀC(4')).

1844

Helvetica Chimica Acta Vol. 87 (2004)

N-Phenyl-20-amide 21a: Yield 71.9 mg (46%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.50. ¹H-NMR

(400 MHz, CDCl₃): 0.79 (s, Me(22)); 0.84 (s, Me(19)); 0.97 (s, Me(21)); 0.97 (s, Me(18)); 2.25 (d, J 18.6,

1 HÀC(15)); 2.64 (d, J 18.6, 1 HÀC(15)); 2.84 (m, HÀC(13)); 3.16 (s, MeSO₂); 4.28 (dd, J 11.5, 4.7,

HÀC(3)); 4.39 (d, J 9.6, 1 HÀC(17)); 4.90 (d, J 9.6, 1 HÀC(17)); 7.10 (m, HÀC(4')); 7.28 (m, HÀC(3'),

HÀC(5')); 7.53 (br. d, J 8.0, HÀC(2'), HÀC(6')); 8.31 (s, NHCO). EI-MS: 389 (2, [M À MeSO₃H] ), 357

(40), 345 (14), 329 (100).

N-(4-Chlorophenyl)-20-amide 21b: Yield 98.5 mg (58%). Colorless oil. R_f(hexane/AcOEt 1 :1) 0.36.

¹H-NMR (400 MHz, (D₆)DMSO): 0.81 (s, Me(22)); 0.87 (s, Me(19)); 0.99 (s, Me(21)); 1.00 (s, Me(18)); 2.32

(d, J 18.7, 1 HÀC(15)); 2.55 (d, J 18.8, 1 HÀC(15)); 2.86 (s, MeSO₂); 3.05 (m, HÀC(13)); 4.29 (dd, J 11.5,

4.9, HÀC(3)); 4.40 (d, J 10.0, 1 HÀC(17)); 5.01 (d, J 10.0, 1 HÀC(17)); 7.23 (br. d, J 8.8, HÀC(2'),

HÀC(6')); 7.57 (br. d, J 8.8, HÀC(3'), HÀC(5')).

N-(3,4-Dichlorophenyl)-20-amide 21c: Yield 135.1 mg (75.2%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.53.

¹H-NMR (400 MHz, (CD₃)₂CO): 0.84 (s, Me(22)); 0.90 (s, Me(19)); 1.02 (s, Me(21)); 1.03 (s, Me(18)); 2.38

(d, J 18.6, 1 HÀC(15)); 2.58 (d, J 18.6, 1 HÀC(15)); 2.84 (m, HÀC(13)); 3.03 (s, MeSO₂); 4.28 (dd, J 11.6,

5.5, HÀC(3)); 4.46 (d, J 10.0, 1 HÀC(17)); 5.01 (d, J 10.0, 1 HÀC(17)); 7.34 (m, HÀC(5'), HÀC(6')); 7.88

(br. s, HÀC(2')). EI-MS: 599 (26, M ), 503 (18).

N-(4-Methoxyphenyl)-20-amide 21d: Yield 109.4 mg (65%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.44.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.91 (s, Me(19)); 1.04 (s, Me(21)); 1.05 (s, Me(18)); 2.32 (d, J

18.6, 1 HÀC(15)); 2.53 (d, J 18.7, 1 HÀC(15)); 3.02 (s, MeSO₂); 3.78 (s, MeO); 4.32 (dd, J 11.8, 4.6,

HÀC(3)); 4.38 (d, J 10.3, 1 HÀC(17)); 5.24 (d, J 10.3, 1 HÀC(17)); 6.84 (br. d, J 8.0, HÀC(3'),

HÀC(5')); 7.37 (br. d, J 8.0, HÀC(2'), HÀC(6')).

N-(1,1'-[Biphenyl]-4-yl)-20-amide 21e: Yield 92.9 mg (51%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.44.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.90 (s, Me(19)); 1.03 (s, Me(21)); 1.03 (s, Me(18)); 2.50 (d, J

18.1, 1 HÀC(15)); 2.62 (d, J 18.0, 1 HÀC(15)); 3.03 (s, MeSO₂); 4.33 (dd, J 11.6, 4.7, HÀC(3)); 4.42 (d, J

10.0, 1 HÀC(17)); 5.17 (d, J 10.0, 1 HÀC(17)); 7.33 (m, HÀC(4'')); 7.42 (m, HÀC(3''), HÀC(5'')); 7.54

(m, 6 H). FAB-MS: 608 (26, [M 1] ), 530 (50), 441 (91), 343 (5).

N-(4-Methylphenyl)-20-amide 21f: Yield 60.5 mg (37%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.48.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.90 (s, Me(19)); 1.03 (s, Me(21)); 1.04 (s, Me(18)); 2.32 (d, J

18.7, 1 HÀC(15)); 2.33 (s, MeÀC(4')); 2.53 (d, J 18.7, 1 HÀC(15)); 3.03 (s, MeSO₂); 4.32 (dd, J 11.8, 4.6,

HÀC(3)); 4.37 (d, J 10.2, 1 HÀC(17)); 5.14 (d, J 10.2, 1 HÀC(17)); 7.03 (br. d, J 8.0, HÀC(3'),

HÀC(5')); 7.28 (br. d, J 8.0, HÀC(2'), HÀC(6')). FAB-MS: 546 (25, [M 1] ). EI-MS: 449 (25, [M À

MeSO₃H] ), 434 (32), 406 (53), 107 (100).

N-(2,4,5-Trichlorophenyl)-20-amide 21g: Yield 97.3 mg (51.1%). Colorless oil. R_f(hexane/AcOEt 3 :1)

0.40. ¹H-NMR (400 MHz, CDCl₃): 0.92 (s, Me(22)); 0.96 (s, Me(19)); 1.05 (s, Me(21)); 1.06 (s, Me(18)); 2.41

(d, J 18.5, 1 HÀC(15)); 2.65 (d, J 18.7, 1 HÀC(15)); 3.03 (s, MeSO₂); 4.32 (dd, J 11.6, 4.7, HÀC(3)); 4.43

(d, J 9.9, 1 HÀC(17)); 5.14 (d, J 9.8, 1 HÀC(17)); 7.49 (s, J 8.0, HÀC(3')); 7.58 (s, HÀC(6')). FAB-MS:

635 (4, M ), 530 (64), 515 (5), 441 (20).

N-(Cyclohexyl)-20-amide 21h: Yield 111.1 mg (68.7%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.30.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.90 (s, Me(19)); 0.99 (s, Me(21)); 1.03 (s, Me(18)); 2.37 (d, J

18.0, 1 HÀC(15)); 2.52 (d, J 18.0, 1 HÀC(15)); 3.02 (s, MeSO₂); 4.32 (dd, J 11.8, 4.6, HÀC(3)); 4.36 (d, J

9.9, 1 HÀC(17)); 5.13 (d, J 9.9, 1 HÀC(17)). FAB-MS: 539 (3, M ), 441 (36).

5. 3-Deoxy-20-secoebelin-2-en-20-oic Acid Lactone 20-Aryl Esters ((1'S,2'S,4'aR,4'bS,8'aS,10'aR)-

3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-Dodecahydro-4'b,8',8',10'a-tetramethyl-5-oxospiro[furan-3(2H),1'(2'H)-phe-

nanthrene]-2'-carboxylic Acid Aryl Esters) 22, 3-Deoxy-20-secoebelin-2-en-20-oic Acid Lactone 20-S-Aryl Esters

((1'S,2'S,4'aR,4'bS,8'aS,10'aR)-3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-Dodecahydro-4'b,8',8',10'a-tetramethyl-5-ox-

ospiro[furan-3(2H),1'(2'H)-phenanthrene]-2'-carbothioic Acid S-Aryl Esters) 23, and N-Aryl-3-deoxy-20-

secoebelin-2-en-20-amide Lactones ((1'S,2'S,4'aR,4'bS,8'aS,10'aR)-N-Aryl-3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-

dodecahydro-4b,8',8',10'a-tetramethyl-5-oxospiro[furan-3(2H),1'(2'H)-phenanthrene]-2'-carboxamides) 24:

General Method. To a soln. of 19, 20, or 21 (0.1 mmol) in N,N-dimethylacetamide (10 ml), Li₂CO₃(0.5 mmol)

was added. The mixture was refluxed for 0.5 h and cooled to r.t. The suspension was taken up with 1m aq. HCl

and extracted with Et₂O (3 Â 10 ml), the org. layer washed with H₂O (3 Â 5 ml), dried (MgSO₄), and

evaporated, and the crude product purified by FC (hexane/AcOEt 5 :1): 22, 23, or 24, resp.

20-Phenyl Ester 22a: From 19a, 33 mg (75.7%) of 22a. Colorless oil. R_f(hexane/AcOEt 5 :1) 0.40. ¹H-NMR

(400 MHz, CDCl₃): 0.93 (s, Me(22)); 0.95 (s, Me(19)); 1.01 (s, Me(21)); 1.11 (s, Me(18)); 2.67 (d, J 18.7,

1 HÀC(15)); 2.75 (d, J 18.7, 1 HÀC(15)); 3.06 (dd, J 3.9, 13.1, HÀC(13)); 4.52 (d, J 10.4, 1 HÀC(17));

4.73 (d, J 10.4, 1 HÀC(17)); 5.44 (m, HÀC(3)); 5.45 (m, HÀC(2)); 7.08 (dd, J 1.2, 8.5, HÀC(2'), HÀC(6'));

Helvetica Chimica Acta Vol. 87 (2004)

1845

7.25 (m, HÀC(4')); 7.40 (m, HÀC(3'), HÀC(5')). ¹³C-NMR (100 MHz, CDCl₃): 16.2 (C(19)); 17.2 (C(21)); 18.8

(C(6)); 19.6 (C(11)); 22.6 (C(18)); 26.3 (C(12)); 31.6 (C(22)); 32.5 (C(15)); 34.6 (C(7)); 36.2 (C(10)); 38.6

(C(8)); 40.7 (C(4)); 40.8 (C(1)); 46.2 (C(9)); 50.0 (C(14)); 51.0 (C(13)); 51.7 (C(5)); 69.6 (C(17)); 120.8 (C(2));

121.4 (C(2'), C(6')); 126.1 (C(4')); 129.5 (C(3'), C(5')); 137.9 (C(3)); 150.2 (C(1')); 172.5 (C(20)); 176.2 (C(16)).

EI-MS: 436 (9, M ), 343 (37), 315 (61), 135 (51), 121 (51), 107 (49), 94 (100).

20-(4-Chlorophenyl) Ester 22b: From 19b, 38 mg (81%) of 22b. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.62.

¹H-NMR (400 MHz, CDCl₃): 0.90 (s, Me(22)); 0.91 (s, Me(19)); 0.98 (s, Me(21)); 1.08 (s, Me(18)); 2.60 (d, J

18.6, 1 HÀC(15)); 2.74 (d, J 18.5, 1 HÀC(15)); 3.02 (dd, J 3.8, 13.2, HÀC(13)); 4.48 (d, J 10.2,

1 HÀC(17)); 4.65 (d, J 10.2, 1 HÀC(17)); 5.41 (m, HÀC(3)); 5.42 (m, HÀC(2)); 6.97 (dd, J 2.4, 8.8,

HÀC(2'), HÀC(6')); 7.33 (br. d, J 8.8, HÀC(3'), HÀC(5')). EI-MS: 470 (25, M ), 343 (45), 315 (100), 301

(7), 136 (79), 107 (66).

20-(2,4-Dichlorophenyl) Ester 22c: From 19c, 38.4 mg (76.1%) of 22c. Colorless oil. R_f(hexane/AcOEt

1

4 :1) 0.60. H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.88 (s, Me(19)); 0.97 (s, Me(21)); 1.08 (s, Me(18));

2.61 (d, J 18.7, 1 HÀC(15)); 2.72 (d, J 18.7, 1 HÀC(15)); 3.03 (dd, J 3.9, 13.1, HÀC(13)); 4.49 (d, J 10.3,

1 HÀC(17)); 4.67 (d, J 10.3, 1 HÀC(17)); 5.41 (m, HÀC(3)); 5.42 (m, HÀC(2)); 7.06 (d, J 8.8, HÀC(6'));

7.26 (dd, J 2.4, 8.8, HÀC(5')); 7.44 (d, J 2.4, HÀC(3')). ¹³C-NMR (100 MHz, CDCl₃): 16.3 (C(19)); 17.3

(C(21)); 19.1 (C(6)); 19.8 (C(11)); 22.7 (C(18)); 26.4 (C(12)); 31.7 (C(22)); 32.6 (C(15)); 34.8 (C(7)); 36.4

(C(10)); 38.6 (C(8)); 40.8 (C(4)); 40.9 (C(1)); 46.3 (C(9)); 50.1 (C(14)); 51.1 (C(13)); 51.8 (C(5)); 69.8 (C(17));

120.0 (C(2)); 124.7 (C(6')); 127.7 (C(2')); 128.3 (C(3')); 130.2 (C(5')); 132.4 (C(4')); 138.1 (C(3)); 145.4 (C(1'));

171.6 (C(20)); 176.3 (C(16)). EI-MS: 505 (8, M ), 343 (72), 315 (100).

20-[4-(Methylthio)phenyl] Ester 22d: From 19d, 34.7 mg (72%) of 22d. Colorless oil. R_f(hexane/AcOEt

4 :1) 0.57. ¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.92 (s, Me(19)); 0.98 (s, Me(21)); 1.08 (s, Me(18));

2.46 (s, MeS); 2.64 (d, J 18.8, 1 HÀC(15)); 2.71 (d, J 18.8, 1 HÀC(15)); 3.04 (dd, J 3.8, 13.2, HÀC(13));

4.47 (d, J 10.2, 1 HÀC(17)); 4.67 (d, J 10.2, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 7.07

(br. d, J 8.8, HÀC(2'), HÀC(6')); 7.25 (br. d, J 8.8, HÀC(3'), HÀC(5')). EI-MS: 482 (12, M ), 343 (45), 140

(100).

20-(4-Methoxyphenyl) Ester 22e: From 19e, 39.1 mg (83.9%) of 22e. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.41. ¹H-NMR (400 MHz, CDCl₃): 0.86 (s, Me(22)); 0.88 (s, Me(19)); 0.99 (s, Me(21)); 1.09 (s, Me(18)); 2.64

(d, J 18.7, 1 HÀC(15)); 2.72 (d, J 18.6, 1 HÀC(15)); 3.03 (dd, J 3.9, 13.1, HÀC(13)); 3.80 (s, MeO); 4.47

(d, J 10.2, 1 HÀC(17)); 4.69 (d, J 10.2, 1 HÀC(17)); 5.41 (m, HÀC(3)); 5.42 (m, HÀC(2)); 6.87 (br. d, J

8.8, HÀC(3'), HÀC(5')); 6.96 (dd, J 2.2, 8.8, HÀC(2'), HÀC(6')). ¹³C-NMR (100 MHz, CDCl₃): 16.4 (C(19));

17.3 (C(21)); 20.0 (C(6)); 19.8 (C(11)); 22.7 (C(18)); 26.4 (C(12)); 31.8 (C(22)); 32.7 (C(15)); 34.8 (C(7)); 36.4

(C(10)); 38.6 (C(8)); 40.8 (C(4)); 40.9 (C(1)); 46.3 (C(9)); 50.2 (C(14)); 51.2 (C(13)); 51.8 (C(5)); 69.8 (C(17));

114.7 (C(3'), C(5')); 121.0 (C(2)); 122.3 (C(2'), C(6'); 140.1 (C(3)); 143.9 (C(1')); 157.6 (C(4')); 173.1 (C(20));

176.4 (C(16)). EI-MS: 466 (18, M ), 343 (3), 315 (8), 124 (100).

20-(Naphthalen-1-yl) Ester 22f: From 19f, 27.2 mg (56%) of 22f. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.62.

¹H-NMR (400 MHz, CDCl₃): 0.96 (s, Me(22)); 0.97 (s, Me(19)); 1.03 (s, Me(21)); 1.14 (s, Me(18)); 2.73 (d, J

18.6, 1 HÀC(15)); 2.81 (d, J 18.6, 1 HÀC(15)); 3.28 (dd, J 3.8, 13.8, HÀC(13)); 4.57 (d, J 10.2,

1 HÀC(17)); 4.82 (d, J 10.2, 1 HÀC(17)); 5.43 (m, HÀC(3)); 5.46 (m, HÀC(2)); 7.21 (d, J 7.6, HÀC(2'));

7.48 (m, HÀC(5')); 7.52 (m, HÀC(3'), HÀC(4')); 7.78 (m, HÀC(6'), HÀC(7')); 7.88 (m, HÀC(8')). EI-MS: 486

(4, M ), 343 (3), 315 (7), 144 (100).

20-(4-Nitrophenyl) Ester 22g: From 19h, 28.9 mg (60%) of 22g. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.42.

¹H-NMR (400 MHz, CDCl₃): 0.90 (s, Me(22)); 0.91 (s, Me(19)); 0.98 (s, Me(21)); 1.10 (s, Me(18)); 2.62 (d, J

18.8, 1 HÀC(15)); 2.80 (d, J 18.8, 1 HÀC(15)); 3.07 (dd, J 4.0, 12.8, HÀC(13)); 4.50 (d, J 10.2,

1 HÀC(17)); 4.64 (d, J 10.2, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 7.25 (br. d, J 9.2,

HÀC(2'), HÀC(6')); 8.27 (br. d, J 9.2, HÀC(3'), HÀC(5')). EI-MS: 481 (5, M ), 343 (40), 315 (59), 109

(100).

20-(Naphthalen-2-yl) Ester 22h: From 19g, 27.2 mg (56%) of 22h. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.60. ¹H-NMR (400 MHz, CDCl₃): 0.89 (s, Me(22)); 0.91 (s, Me(19)); 0.98 (s, Me(21)); 1.08 (s, Me(18)); 2.68

(d, J 18.6, 1 HÀC(15)); 2.74 (d, J 18.6, 1 HÀC(15)); 3.08 (dd, J 3.2, 12.8, HÀC(13)); 4.52 (d, J 10.2,

1 HÀC(17)); 4.74 (d, J 10.2, 1 HÀC(17)); 5.41 (m, HÀC(3)); 5.42 (m, HÀC(2)); 7.18 (dd, J 2.4, 8.8, 1 H);

7.49 (m, 3 H); 7.82 (m, 3 H). EI-MS: 486 (7, M ), 343 (1), 315 (3), 144 (100).

20-(4-Methylphenyl) Ester 22i: From 19i, 27 mg (60%) of 22i. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.60.

¹H-NMR (400 MHz, CDCl₃): 0.90 (s, Me(22)); 0.92 (s, Me(19)); 0.97 (s, Me(21)); 1.08 (s, Me(18)); 2.34

(s, MeÀC(4')); 2.64 (d, J 18.8, 1 HÀC(15)); 2.71 (d, J 18.8, 1 HÀC(15)); 3.02 (dd, J 4.0, 13.2, HÀC(13));

4.48 (d, J 10.2, 1 HÀC(17)); 4.69 (d, J 10.2, 1 HÀC(17)); 5.41 (m, HÀC(3)); 5.42 (m, HÀC(2)); 6.92

1846

Helvetica Chimica Acta Vol. 87 (2004)

(br. d, J 8.4, HÀC(3'), HÀC(5')); 7.17 (br. d, J 8.4, HÀC(2'), HÀC(6')). EI-MS: 450 (62, M ), 343 (11), 315

(59), 135 (58), 108 (100).

20-([1,1'-Biphenyl]-4-yl) Ester 22j: From 19j, 31.8 mg (62.1%) of 22j. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.60. ¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.92 (s, Me(19)); 0.98 (s, Me(21)); 1.08 (s, Me(18)); 2.65

(d, J 18.6, 1 HÀC(15)); 2.75 (d, J 18.6, 1 HÀC(15)); 3.07 (dd, J 4.0, 13.2, HÀC(13)); 4.50 (d, J 10.1,

1 HÀC(17)); 4.71 (d, J 10.1, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 7.04 (br. d, J 8.4,

HÀC(3'), HÀC(5')); 7.35 (m, HÀC(4'')); 7.43 (m, HÀC(2'), HÀC(6')); 7.48 (m, 4 H). EI-MS: 512 (19, M ),

343 (7), 315 (31), 170 (100).

20-S-(4-Chlorophenyl) Ester 23a: From 20b, 30.7 mg (63.2%) of 23a. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.53. ¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.90 (s, Me(19)); 0.96 (s, Me(21)); 1.10 (s, Me(18)); 2.61

(d, J 18.6, 1 HÀC(15)); 2.67 (d, J 18.6, 1 HÀC(15)); 3.07 (dd, J 4.0, 13.2, HÀC(13)); 4.42 (d, J 10.1,

1 HÀC(17)); 4.77 (d, J 10.1, 1 HÀC(17)); 5.39 (m, HÀC(3)); 5.40 (m, HÀC(2)); 7.30 (br. d, J 8.0, HÀC(2'),

HÀC(6')); 7.39 (br. d, J 8.0, HÀC(3'), HÀC(5')). EI-MS: 486 (4, M ), 344 (11).

20-S-(2,6-Dichlorophenyl) Ester 23b: From 20c, 41.7 mg (28.3%) of 23b. Colorless oil. R_f(hexane/AcOEt

4 :1) 0.63. ¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.95 (s, Me(19)); 1.08 (s, Me(21)); 1.08 (s, Me(18));

2.67 (d, J 18.6, 1 HÀC(15)); 2.71 (d, J 18.6, 1 HÀC(15)); 3.14 (dd, J 4.0, 13.2, HÀC(13)); 4.44 (d, J 10.4,

1 HÀC(17)); 4.81 (d, J 10.4, 1 HÀC(17)); 5.41 (m, HÀC(3)); 5.42 (m, HÀC(2)); 7.31 (m, HÀC(4')); 7.44

(br. d, J 8.0, HÀC(3'), HÀC(5')).

N-Phenyl-20-amide 24a: From 21a, 31 mg (73%) of 24a. Colorless oil. R_f(hexane/AcOEt 1:1) 0.52.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.92 (s, Me(19)); 0.99 (s, Me(21)); 1.08 (s, Me(18)); 2.55 (d, J

18.4, 1 HÀC(15)); 2.62 (d, J 18.4, 1 HÀC(15)); 4.43 (d, J 10.1, 1 HÀC(17)); 5.10 (d, J 10.1, 1 HÀC(17));

5.41 (m, HÀC(3)); 5.43 (m, HÀC(2)); 7.12 (m, HÀC(4')); 7.29 (m, HÀC(3'), HÀC(5')); 7.45 (m, HÀC(2'),

HÀC(6')).

N-(3,4-Dichlorophenyl)-20-amide 24b: From 21c, 34.2 mg (68%) of 24b. Colorless oil. R_f(hexane/AcOEt

1:1) 0.42. ¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.90 (s, Me(19)); 0.97 (s, Me(21)); 1.05 (s, Me(18));

2.37 (d, J 17.7, 1 HÀC(15)); 2.63 (d, J 17.6, 1 HÀC(15)); 4.47 (d, J 10.1, 1 HÀC(17)); 4.55 (d, J 10.1,

1 HÀC(17)); 5.41 (m, HÀC(3)); 5.42 (m, HÀC(2)); 7.35 (m, HÀC(5'), HÀC(6')); 7.71 (br. s, HÀC(2')).

N-(4-Chlorophenyl)-20-amide 24c: From 21b, 23.4 mg (49.8%) of 24c. Colorless oil. R_f(hexane/AcOEt

1

4 :1) 0.30. H-NMR (400 MHz, CDCl₃): 0.90 (s, Me(22)); 0.91 (s, Me(19)); 0.99 (s, Me(21)); 1.04 (s, Me(18));

2.42 (d, J 18.6, 1 HÀC(15)); 2.63 (d, J 18.6, 1 HÀC(15)); 4.47 (d, J 10.0, 1 HÀC(17)); 5.11 (d, J 10.0,

1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 7.39 (m, 2 H); 7.71 (m, 2 H).

N-(2,4,5-Trichlorophenyl)-20-amide 24d: From 21g, 29.9 mg (55.5%) of 24d. Colorless oil. R_f(hexane/

AcOEt 4 :1) 0.37. ¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.91 (s, Me(19)); 0.98 (s, Me(21)); 1.07

(s, Me(18)); 2.42 (d, J 19.5, 1 HÀC(15)); 2.65 (d, J 19.6, 1 HÀC(15)); 4.47 (d, J 9.8, 1 HÀC(17)); 4.95

(d, J 9.7, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 7.48 (s, HÀC(3')); 7.55 (s, HÀC(6')).

N-(1,1'-[Biphenyl]-4-yl)-20-amide 24e: From 21e, 36.9 mg (72.3%) of 24c. Colorless oil. R_f(hexane/AcOEt

1

4 :1) 0.20. H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 0.91 (s, Me(19)); 0.97 (s, Me(21)); 1.07 (s, Me(18));

2.48 (d, J 18.0, 1 HÀC(15)); 2.62 (d, J 18.0, 1 HÀC(15)); 4.51 (d, J 10.0, 1 HÀC(17)); 5.18 (d, J 10.0,

1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 7.32 (m, 1 H); 7.42 (m, 2 H); 7.55 (m, 6 H). EI-MS: 511

(76, M ), 169 (100).

N-Cyclohexyl-20-amide 24f: From 21h, 32.6 mg (73.9%) of 24f. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.23.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(22)); 0.88 (s, Me(19)); 0.96 (s, Me(21)); 1.00 (s, Me(18)); 2.37 (d, J

18.0, 1 HÀC(15)); 2.53 (d, J 18.0, 1 HÀC(15)); 4.41 (d, J 9.9, 1 HÀC(17)); 5.12 (d, J 9.9, 1 HÀC(17)). EI-

MS: 441 (M ).

6. Oxidation of 2-Ene Derivatives 22 with CrO₃: 3-Deoxy-1-oxo-20-secoebelin-2-en-20-oic Acid Lactone

Aryl Esters ((1'S,2'S,4'aS,4'bS,8'aS,10'aR)-3',4,4',4'a,4'b,5,5',8,8'a,9',10',10'a-Dodecahydro-4'b,8',8',10'a-tetra-

methyl-5,5'-dioxospiro[furan-3(2H),1'(2'H)-phenanthrene]-2'-carboxylic Acid Aryl Esters) 5: General Method.

To a soln. of 22 (0.1 mmol) in AcOH (1 ml), CrO₃in AcOH (1 ml) was added dropwise at 808, and stirring was

continued for 1 h. After evaporation, the residue was taken up with H₂O and extracted with CH₂Cl₂, the org.

phase evaporated, and the residue purified by CC (SiO₂, hexane/AcOEt 2 :1): 5 and the by-products 25.

20-Phenyl Ester 5a: From 22a, 11.7 mg (26%) of 5a. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.33. ¹H-NMR

(400 MHz, CDCl₃): 0.87 (s, Me(22)); 1.11 (s, Me(19)); 1.13 (s, Me(21)); 1.15 (s, Me(18)); 2.69 (d, J 18.7,

1 HÀC(15)); 2.71 (d, J 18.6, 1 HÀC(15)); 3.05 (dd, J 3.5, 13.0, HÀC(13)); 4.46 (d, J 10.6, 1 HÀC(17));

4.76 (d, J 10.3, 1 HÀC(17)); 5.71 (d, J 10.3, HÀC(2)); 6.35 (d, J 10.2, HÀC(3)); 7.06 (br. d, J 7.3,

HÀC(2'), HÀC(6')); 7.26 (m, HÀC(4')); 7.37 (m, HÀC(3'), HÀC(5')). ¹³C-NMR (100 MHz, CDCl₃): 15.8

(C(19)); 17.9 (C(21)); 18.4 (C(6)); 21.8 (C(22)); 22.7 (C(11)); 26.3 (C(12)); 31.0 (C(18)); 32.3 (C(15)); 34.8

Helvetica Chimica Acta Vol. 87 (2004)

1847

(C(7)); 36.4 (C(8)); 40.8 (C(4)); 43.1 (C(9)); 46.6 (C(13)); 47.4 (C(10)); 50.1 (C(14)); 50.9 (C(5)); 69.9 (C(17));

121.4 (C(2'), C(6')); 124.1 (C(2)); 126.1 (C(4')); 129.5 (C(3'), C(5')); 150.2 (C(1')); 154.7 (C(3)); 172.4 (C(20));

176.2 (C(16)); 206.1 (C(1)). EI-MS: 450 (27, M ), 357 (35), 329 (100), 217 (30).

20-(2,4-Dichlorophenyl) Ester 5b: From 22c, 14.5 mg (27.9%) of 5b. Colorless oil. R_f(hexane/AcOEt 1 :1)

0.82. ¹H-NMR (400 MHz, CDCl₃): 0.93 (s, Me(22)); 1.09 (s, Me(19)); 1.12 (s, Me(21)); 1.14 (s, Me(18)); 2.65

(d, J 18.7, 1 HÀC(15)); 2.73 (d, J 18.6, 1 HÀC(15)); 3.12 (dd, J 3.5, 13.0, HÀC(13)); 4.46 (d, J 10.0,

1 HÀC(17)); 4.76 (d, J 10.0, 1 HÀC(17)); 5.70 (d, J 10.0, HÀC(2)); 6.35 (d, J 10.1, HÀC(3)); 7.03

(br. d, J 8.4, HÀC(6')); 7.26 (m, HÀC(5')); 7.44 (d, J 2.4, HÀC(3')). EI-MS: 519 (4, M ), 373 (13), 357 (41),

329 (100), 168 (38).

20-(4-Chlorophenyl) Ester 5c: From 22b, 10.9 mg (22.5%) of 5c. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.53.

¹H-NMR (400 MHz, CDCl₃): 1.11 (s, Me(22)); 1.13 (s, Me(19)); 1.15 (s, Me(21)); 1.23 (s, Me(18)); 2.62 (d, J

18.7, 1 HÀC(15)); 2.70 (d, J 18.6, 1 HÀC(15)); 3.12 (dd, J 3.5, 13.0, HÀC(13)); 4.46 (d, J 10.3,

1 HÀC(17)); 4.72 (d, J 10.3, 1 HÀC(17)); 5.71 (d, J 10.3, HÀC(2)); 6.35 (d, J 10.4, HÀC(3)); 7.02

(br. d, J 8.8, HÀC(2'), HÀC(6')); 7.35 (d, J 8.8, HÀC(3'), HÀC(5')). ¹³C-NMR (100 MHz, CDCl₃): 15.8

(C(19)); 18.1 (C(21)); 18.4 (C(6)); 21.9 (C(22)); 22.6 (C(11)); 26.2 (C(12)); 31.0 (C(18)); 32.4 (C(15)); 34.8

(C(7)); 36.4 (C(8)); 40.7 (C(4)); 43.1 (C(9)); 46.7 (C(13)); 47.5 (C(10)); 50.5 (C(14)); 50.9 (C(5)); 69.7 (C(17));

122.8 (C(2'), C(6')); 124.1 (C(2)); 129.6 (C(3'), C(5')); 132.5 (C(4')); 149.2 (C(1')); 154.7 (C(3)); 171.7 (C(20));

176.1 (C(16)); 206.1 (C(1)). EI-MS: 484 (5, M ), 357 (30), 329 (100).

20-(4-Nitrophenyl) Ester 5d: From 22g, 14.5 mg (29.4%) of 5d. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.36.

¹H-NMR (400 MHz, CDCl₃): 1.11 (s, Me(22)); 1.14 (s, Me(19)); 1.16 (s, Me(21)); 1.24 (s, Me(18)); 2.59 (d, J

18.7, 1 HÀC(15)); 2.75 (d, J 18.6, 1 HÀC(15)); 3.18 (dd, J 3.5, 13.0, HÀC(13)); 4.47 (d, J 10.2,

1 HÀC(17)); 4.71 (d, J 10.2, 1 HÀC(17)); 5.71 (d, J 10.4, HÀC(2)); 6.36 (d, J 10.4, HÀC(3)); 7.26

(dd, J 2.4, 7.2, HÀC(2'), HÀC(6')); 8.27 (dd, J 2.4, 7.2, HÀC(3'), HÀC(5')). ¹³C-NMR (100 MHz, CDCl₃):

15.7 (C(19)); 18.1 (C(21)); 18.4 (C(6)); 21.8 (C(22)); 22.6 (C(11)); 26.1 (C(12)); 30.9 (C(18)); 32.5 (C(15)); 34.8

(C(7)); 36.3 (C(8)); 40.7 (C(4)); 43.1 (C(9)); 46.8 (C(13)); 47.4 (C(10)); 50.5 (C(14)); 50.9 (C(5)); 69.5 (C(17));

122.5 (C(2'), C(6')); 124.0 (C(2)); 125.2 (C(3'), C(5')); 145.6 (C(4')); 154.8 (C(1')); 154.7 (C(3)); 171.5 (C(20));

175.8 (C(16)); 205.9 (C(1)). EI-MS: 357 (7, [M À NO₂C₆H₄O] ), 329 (18), 137 (17).

20-(4-Methylphenyl) Ester 5e: From 22i, 8.3 mg (18%) of 5e. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.38.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(22)); 1.09 (s, Me(19)); 1.12 (s, Me(21)); 1.13 (s, Me(18)); 2.34

(s, MeÀC(4')); 2.65 (d, J 18.7, 1 HÀC(15)); 2.72 (d, J 18.6, 1 HÀC(15)); 3.06 (dd, J 3.5, 13.0, HÀC(13));

4.47 (d, J 10.2, 1 HÀC(17)); 4.70 (d, J 10.2, 1 HÀC(17)); 5.72 (d, J 10.4, HÀC(2)); 6.35 (d, J 10.4,

HÀC(3)); 6.93 (br. d, J 8.0, HÀC(2'), HÀC(6')); 7.15 (br. d, J 8.0, HÀC(3'), HÀC(5')). EI-MS: 464 (8,

M ), 357 (4), 329 (15), 135 (17), 108 (100).

3-Deoxy-3-oxo-20-secoebelin-1-en-20-oic Acid Lactone Phenyl Ester ((1'S,2'S,4'aR,4'bR,8'aR,10'aR)-

3',4,4',4'a,4'b,5,7',8'8'a,9'10'10'a-Dodecahydro-4'b,8',8'10'a-tetramethyl-5,7'-dioxospiro[furan-3(2H),1'(2'H)-phen-

anthrene]-2'-carboxylic Acid Phenyl Ester; 25a): From 22a, 7.2 mg (16%) of 25a. Colorless oil. R_f(hexane/

AcOEt 4 :1) 0.21. ¹H-NMR (400 MHz, CDCl₃): 1.11 (s, Me(21)); 1.12 (s, Me(18)); 1.17 (s, Me(19)); 1.18

(s, Me(22)); 2.72 (d, J 18.7, 1 HÀC(15)); 2.74 (d, J 18.3, 1 HÀC(15)); 3.10 (m, HÀC(13)); 4.45 (d, J 10.7,

1 HÀC(17)); 4.71 (d, J 10.7, 1 HÀC(17)); 5.89 (d, J 10.2, HÀC(2)); 7.08 (d, J 10.2, HÀC(1)); 7.06

(br. d, J 8.4, HÀC(2'), HÀC(6')); 7.27 (m, HÀC(4')); 7.39 (m, HÀC(3'), HÀC(5')).

7. Oxidation of 2-Ene Derivatives 22, 23, or 24 with N-Bromosuccinimide (NBS): 20-Aryl Esters 5, 20-S-Aryl

Esters ((1'S,2'S,4'aS,4'bS,8'aS,10'aR)-3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-Dodecahydro-4'b,8',8',10'a-tetramethyl-

5,5'-dioxospiro[furan-3(2H),1'(2'H)-phenanthrene]-2'-carbothioic Acid S-Aryl Esters) 6, and N-Aryl-20-amides

((1'S,2'S,4'aS,4'bS,8'aS,10'aR)-N-Aryl-3',4,4',4'a,4'b,5,5',8',8'a,9',10'10'a-dodecahydro-4'b,8',8',10'a-tetramethyl-

5,5'-dioxospiro[furan-3(2H),1'(2'H)-phenanthrene]-2'-carboxamides) 7: General Method. 7.1. To a soln. of 22,

23, or 24 (0.025 mmol) in 1,4-dioxane (5 ml), CaCO₃(0.19 mmol) and NBS (0.15 mmol) were added. The

mixture was heated at 508 for 6 h under irradiation. After neutralization with 5% aq. HCl soln., the suspension

was extracted with Et₂O and the org. layer washed with H₂O, dried (MgSO₄), and evaporated: yellow oil A. This

crude product could be used directly in the next step or purified by FC (hexane/AcOEt 3 :1): 5, 6, or 7, resp., and

the 1-bromo-2-ene derivatives 26, 27, or 28, resp.

7.2. To the yellow oil A in 1,4-dioxane (2 ml) were added CaCO₃(0.026 mmol) and H₂O (20 ml). The

mixture was refluxed for 5 h. After neutralization with 5% aq. HCl soln., the mixture was extracted with Et₂O

and the org. layer washed with brine, dried (MgSO₄), and evaporated: yellowish oil B.

7.3. To the yellowish oil B in CH₂Cl₂(5 ml) was added PCC (0.1 mmol), and the soln. was refluxed for 6 h.

The mixture was diluted with CH₂Cl₂, the soln. washed with 10% aq. K₂CO₃soln., and H₂O, dried (MgSO₄), and

evaporated, and the obtained brown oil purified by FC (SiO₂, hexane/CHCl₃/Me₂CO 15 :5 :1): 5, 6, or 7, resp.

1848

Helvetica Chimica Acta Vol. 87 (2004)

20-(4-Methoxyphenyl) Ester 5f: From 22e, 6.9 mg (57.4%) of 5f. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.37.

¹H-NMR (400 MHz, CDCl₃): 1.11 (s, Me(22)); 1.13 (s, Me(19)); 1.15 (s, Me(21)); 1.20 (s, Me(18)); 2.68 (d, J

18.4, 1 HÀC(15)); 2.71 (d, J 18.4, 1 HÀC(15)); 3.06 (dd, J 4.4, 13.2, HÀC(13)); 3.80 (s, MeO); 4.48 (d, J

10.4, 1 HÀC(17)); 4.77 (d, J 10.4, 1 HÀC(17)); 5.72 (d, J 10.0, HÀC(2)); 6.36 (d, J 10.0, HÀC(3)); 6.88

(br. d, J 9.2, HÀC(3'), HÀC(5')); 6.98 (br. d, J 9.2, HÀC(2'), HÀC(6')). ESI-MS: 503.3 ([M Na] ).

20-(Naphthalen-1-yl) Ester 5g: From 22f, 5.3 mg (44.7%) of 5g. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.10.

¹H-NMR (400 MHz, CDCl₃): 1.10 (s, Me(22)); 1.14 (s, Me(19)); 1.17 (s, Me(21)); 1.19 (s, Me(18)); 2.68 (d, J

18.4, 1 HÀC(15)); 2.77 (d, J 18.4, 1 HÀC(15)); 3.09 (dd, J 4.4, 13.2, HÀC(13)); 4.49 (d, J 10.2,

1 HÀC(17)); 4.80 (d, J 10.2, 1 HÀC(17)); 5.72 (d, J 10.4, HÀC(2)); 6.37 (d, J 10.4, HÀC(3)); 7.15

(br. d, J 7.6, HÀC(2')); 7.36 (m, HÀC(5')); 7.45 (m, HÀC(3'), HÀC(4')); 7.58 (m, 3 H). ESI-MS: 501 ([M

Na] ).

20-(3,4,5-Trimethoxyphenyl) Ester 5h: 22.8 mg (14.1% based on 15) of 5h. Colorless oil. R_f(hexane/AcOEt

1:1) 0.60. ¹H-NMR (400 MHz, CDCl₃): 1.07 (s, Me(22)); 1.09 (s, Me(19)); 1.12 (s, Me(21)); 1.19 (s, Me(18));

2.66 (d, J 18.6, 1 HÀC(15)); 2.71 (d, J 18.6, 1 HÀC(15)); 3.13 (dd, J 3.7, 13.3, HÀC(13)); 3.82

(s, MeOÀC(4')); 3.86 (s, MeOÀC(3'), MeOÀC(5')); 4.47 (d, J 10.3, 1 HÀC(17)); 4.76 (d, J 10.3,

1 HÀC(17)); 5.69 (d, J 10.1, HÀC(2)); 6.35 (d, J 10.1, HÀC(3)); 6.52 (br. s, HÀC(2'), HÀC(6')).

¹³C-NMR (100 MHz, CDCl₃): 14.3 (C(19)); 18.0 (C(21)); 18.4 (C(6)); 21.8 (C(22)); 22.7 (C(11)); 26.4

(C(12)); 30.9 (C(18)); 32.2 (C(15)); 34.9 (C(7)); 36.3 (C(8)); 40.7 (C(4)); 42.9 (C(9)); 46.6 (C(13)); 47.4 (C(10));

50.1 (C(14)); 50.8 (C(5)); 56.2 (MeOÀC(4')); 61.2 (MeOÀC(3'), MeOÀC(5')); 69.9 (C(17)); 102.9 (C(2'),

C(6')); 124.1 (C(2)); 141.2 (C(4')); 151.5 (C(1')); 153.1 (C(3'), C(5')); 154.7 (C(3)); 171.7 (C(20)); 176.4 (C(16));

206.2 (C(1)). ESI-MS: 565.3 ([M 2 Na] ).

20-S-Phenyl Ester 6a: 26.8 mg (19.2% based on 15) of 6a. Colorless oil. R_f(hexane/AcOEt 1:1) 0.70.

¹H-NMR (400 MHz, CDCl₃): 1.08 (s, Me(22)); 1.11 (s, Me(19)); 1.12 (s, Me(21)); 1.21 (s, Me(18)); 2.65

(br. s, 2 HÀC(15)); 3.11 (dd, J 3.6, 13.2, HÀC(13)); 4.41 (d, J 10.3, 1 HÀC(17)); 4.87 (d, J 10.3,

1 HÀC(17)); 5.69 (d, J 10.1, HÀC(2)); 6.33 (d, J 10.1, HÀC(3)); 7.36 (m, 2 H); 7.41 (m, 3 H). ESI-MS:

489.3 ([M Na] ).

20-S-(4-Chlorophenyl) Ester 6b: From 23a, 3.8 mg (30.5%) of 6b. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.33. ¹H-NMR (400 MHz, CDCl₃): 1.06 (s, Me(22)); 1.11 (s, Me(19)); 1.12 (s, Me(21)); 1.21 (s, Me(18)); 2.60

(d, J 18.6, 1 HÀC(15)); 2.66 (d, J 18.6, 1 HÀC(15)); 3.09 (dd, J 3.6, 13.2, HÀC(13)); 4.40 (d, J 10.3,

1 HÀC(17)); 4.83 (d, J 10.3, 1 HÀC(17)); 5.69 (d, J 10.1, HÀC(2)); 6.34 (d, J 10.1, HÀC(3)); 7.29 (dd, J

6.7, 1.8, HÀC(3'), HÀC(5')); 7.39 (dd, J 6.7, 1.8, HÀC(2'), HÀC(6')). ESI-MS: 523.3 ([M Na] ).

20-S-(4-Methoxyphenyl) Ester 6c: 63.2 mg (42.5% based on 15) of 6c. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.32. ¹H-NMR (400 MHz, CDCl₃): 1.09 (s, Me(22)); 1.12 (s, Me(19)); 1.14 (s, Me(21)); 1.17 (s, Me(18)); 2.70

(br. s, 2 HÀC(15)); 3.09 (dd, J 4.4, 13.2, HÀC(13)); 3.83 (s, MeO); 4.41 (d, J 10.3, 1 HÀC(17)); 4.88 (d, J

10.3, 1 HÀC(17)); 5.70 (d, J 10.1, HÀC(2)); 6.35 (d, J 10.1, HÀC(3)); 6.96 (br. d, J 8.8, HÀC(3'),

HÀC(5')); 7.29 (dd, J 8.8, HÀC(2'), HÀC(6')). ESI-MS: 519.4 ([M Na] ).

N-Phenyl-20-amide 7a: 45.8 mg (34.0% based on 15) of 7a. Colorless oil. R_f(hexane/AcOEt 1:1) 0.45.

¹H-NMR (400 MHz, CDCl₃): 1.08 (s, Me(22)); 1.10 (s, Me(19)); 1.11 (s, Me(21)); 1.18 (s, Me(18)); 2.57 (d, J

18.0, 1 HÀC(15)); 2.61 (d, J 18.0, 1 HÀC(15)); 4.46 (d, J 10.1, 1 HÀC(17)); 5.13 (d, J 10.1, 1 HÀC(17));

5.69 (d, J 10.1, HÀC(2)); 6.34 (d, J 10.1, HÀC(3)); 7.13 (m, HÀC(4')); 7.31 (m, HÀC(3'), HÀC(5')); 7.44

(br. d, J 6.4, HÀC(2'), HÀC(6')). ESI-MS: 472.4 ([M Na] ).

N-(4-Chlorophenyl)-20-amide 7b: 38.4 mg (26.5% based on 15) of 7b. Colorless oil. R_f(hexane/AcOEt

1:1) 0.45. ¹H-NMR (400 MHz, CDCl₃): 1.09 (s, Me(22)); 1.12 (s, Me(19)); 1.14 (s, Me(21)); 1.20 (s, Me(18));

2.48 (d, J 18.3, 1 HÀC(15)); 2.60 (d, J 18.3, 1 HÀC(15)); 4.45 (d, J 10.1, 1 HÀC(17)); 5.08 (d, J 10.1,

1 HÀC(17)); 5.69 (d, J 10.1, HÀC(2)); 6.34 (d, J 10.1, HÀC(3)); 7.31 (br. d, J 8.8, HÀC(3'), HÀC(5'));

7.47 (d, J 8.8, HÀC(2'), HÀC(6')). ESI-MS: 506.3 ([M Na] ).

N-(4-Methoxyphenyl)-20-amide 7c: 25.6 mg (17.8% based on 15) of 7c. Colorless oil. R_f(hexane/AcOEt

1:1) 0.48. ¹H-NMR (400 MHz, CDCl₃): 1.04 (s, Me(22)); 1.08 (s, Me(19)); 1.12 (s, Me(21)); 1.15 (s, Me(18));

2.60 (d, J 18.3, 1 HÀC(15)); 3.24 (d, J 18.3, 1 HÀC(15)); 3.80 (s, MeO); 4.45 (d, J 10.1, 1 HÀC(17)); 5.08

(d, J 10.1, 1 HÀC(17)); 5.70 (d, J 10.1, HÀC(2)); 6.33 (d, J 10.1, HÀC(3)); 6.89 (br. d, J 8.8, HÀC(3'),

HÀC(5')); 7.03 (d, J 8.8, HÀC(2'), HÀC(6')).

1-Bromo-3-deoxy-20-secoebelin-2-en-20-oic Acid Lactone Phenyl Ester ((1'S,2'S,4'aS,4'bS,8'aS,10'aR)-5-

Bromo-3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-dodecahydro-4'b,8',8',10'a-tetramethyl-5-oxospiro[furan-3(2H),1'(2'H)-

phenanthrene]-2'-carboxylic Acid Phenyl Ester; 26a). From 22a, 4.9 mg (39.6%) of 26a. Colorless oil. R_f

(hexane/AcOEt 4 :1) 0.35. ¹H-NMR (400 MHz, (CD₃)₂CO): 0.95 (s, Me(22)); 1.05 (s, Me(19)); 1.09 (s, Me(21));

1.19 (s, Me(18)); 2.63 (d, J 18.4, 1 HÀC(15)); 2.78 (d, J 18.4, 1 HÀC(15)); 3.17 (dd, J 3.7, 13.6, HÀC(13));

Helvetica Chimica Acta Vol. 87 (2004)

1849

4.54 (d, J 10.4, 1 HÀC(17)); 4.62 (d, J 10.4, 1 HÀC(17)); 4.72 (d, J 5.6, HÀC(1)); 5.48 (d, J 9.6,

HÀC(3)); 5.84 (dd, J 5.6, 9.6, HÀC(2)); 7.12 (br. d, J 8.0, HÀC(2'), HÀC(6')); 7.24 (m, HÀC(4')); 7.39

(m, HÀC(3'), HÀC(5')). ¹³C-NMR (100 MHz, CDCl₃): 15.5 (C(19)); 17.1 (C(21)); 19.5 (C(6)); 23.4 (C(22));

20.1 (C(11)); 26.6 (C(12)); 30.8 (C(18)); 32.3 (C(15)); 35.2 (C(7)); 35.6 (C(8)); 40.8 (C(4)); 41.3 (C(10)); 45.3

(C(13)); 46.9 (C(9)); 47.1 (C(5)); 51.3 (C(14)); 63.3 (C(1)); 70.0 (C(17)); 122.6 (C(2'), C(6')); 124.8 (C(2)); 126.7

(C(4')); 130.2 (C(3'), C(5')); 140.4 (C(3)); 151.6 (C(1')); 173.4 (C(20)); 176.3 (C(16)). EI-MS: 419 (4, [M À

Br] ), 406 (5), 378 (7), 341 (9), 313 (18).

8. (20E)-3-O-(Methylsulfonyl)-22-secoebelin-22-oic Acid Lactone 22-Aryl Esters ((2E)-2-Methyl-3-

{(1'S,2'R,4'aR,4'bR,7'S,8'aR,10'aR)-tetradecahydro-4'b,8',8',10'a-tetramethyl-7'-[(methylsulfonyl)oxy]-5-oxo-

spiro[furan-3(2H),1'(2'H)-phenanthren]-2'-yl}prop-2-enoic Acid Aryl Esters) 30, (20E)-3-O-(Methylsulfonyl)-

22-secoebelin-22-oic Acid Lactone 22-S-Aryl Esters ((2E)-2-Methyl-3-{(1'S,2'R,4'aR,4'bR,7'S,8'aR,10'aR)-

tetradecahydro-4'b,8',8',10'a-tetramethyl-7'-[(methylsulfonyl)oxy]-5-oxospiro[furan-3(2H),1'(2'H)-phenan-

thren]-2'-yl}prop-2-enethioic Acid S-Aryl Esters) 31, or (20E)-N-Aryl-3-O-(Methylsulfonyl)-22-secoebelin-22-

amide Lactones ((2E)-N-Aryl-2-methyl-3-{(1'S,2'R,4'aR,4'bR,7'S,8'aR,10'aR)-tetradecahydro-4'b,8',8',10'a-

tetramethyl-7'-[(methylsulfonyl)oxy]-5-oxospiro[furan-3(2H),1'(2'H)-phenanthren]-2'yl}prop-2-enamides) 32:

General Method. To a soln of 16 (81.6 mg, 0.17 mmol) in CCl₄(10 ml), NBS (33.8 mg, 0.19 mmol) was added

under N₂. The flask was irradiated with a 100-W flood lamp, and the spontaneous reflux was allowed to continue

for 5 min. Then the mixture containing acyl bromide 29 was cooled to 08 and treated directly with the substituted

phenol, thiophenol, or aniline (0.2 mmol in each case) in the presence of Et₃N (0.17 mmol). Stirring was

continued for 1 h at r.t. After evaporation, the residue was diluted with CH₂Cl₂(10 ml), the soln. washed with

H₂O, dried (MgSO₄), and evaporated, and the crude product purified by CC (SiO₂, hexane/AcOEt (3 :1): 30, 31,

or 32, resp.

22-Phenyl Ester 30a: Yield 58.5 mg (60.2%). Colorless oil. R_f(hexane/AcOEt 3 :1) 0.28. ¹H-NMR

(400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.92 (s, Me(19)); 1.04 (s, Me(24)); 1.09 (s, Me(18)); 1.99 (br. s, Me(23));

2.06 (d, J 18.3, 1 HÀC(15)); 2.56 (d, J 18.7, 1 HÀC(15)); 2.91 (m, HÀC(13)); 3.02 (s, MeSO₂); 4.34 (dd, J

4.5, 11.3, HÀC(3)); 4.38 (d, J 10.4, 1 HÀC(17)); 4.45 (d, J 10.6, 1 HÀC(17)); 6.79 (br. d, J 10.7,

HÀC(20)); 7.10 (dd, J 1.0, 8.4, HÀC(2'), HÀC(6')); 7.24 (m, HÀC(4')); 7.39 (m, HÀC(3'), HÀC(5')). EI-

MS: 479 (8, [M À PhO] ), 476 (6), 383 (100). FAB-MS: 573 (23, [M 1] ), 479 (100), 383 (16).

22-(4-Chlorophenyl) Ester 30b: Yield 44.4 mg (43%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.42. ¹H-NMR

(400 MHz, CDCl₃): 0.86 (s, Me(25)); 0.94 (s, Me(19)); 1.08 (s, Me(24)); 1.11 (s, Me(18)); 2.00 (d, J 1.2,

Me(23)); 2.05 (d, J 18.4, 1 HÀC(15)); 2.58 (d, J 18.4, 1 HÀC(15)); 2.93 (ddd, J 2.0, 3.6, 10.4, HÀC(13));

3.03 (s, MeSO₂); 4.36 (dd, J 5.2, 12.0, HÀC(3)); 4.40 (d, J 10.4, 1 HÀC(17)); 4.46 (d, J 10.4, 1 HÀC(17));

6.79 (dd, J 1.2, 10.4, HÀC(20)); 7.07 (dd, J 1.6, 8.2, HÀC(2'), HÀC(6')); 7.36 (dd, J 1.6, 8.4, HÀC(3'),

HÀC(5')).

22-(4-Methoxyphenyl) Ester 30c: Yield 55.6 mg (54.3%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.47.

¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(25)); 0.91 (s, Me(19)); 1.03 (s, Me(24)); 1.07 (s, Me(18)); 1.97 (d, J

1.2, Me(23)); 2.05 (d, J 18.0, 1 HÀC(15)); 2.53 (d, J 18.4, 1 HÀC(15)); 2.88 (ddd, J 2.0, 3.6, 10.4,

HÀC(13)); 3.01 (s, MeSO₂); 3.78 (s, MeO); 4.37 (dd, J 4.8, 11.6, HÀC(3)); 4.37 (d, J 10.8, 1 HÀC(17)); 4.42

(d, J 10.8, 1 HÀC(17)); 6.75 (dd, J 1.2, 10.8, HÀC(20)); 6.89 (br. d, J 9.2, HÀC(3'), HÀC(5')); 6.99

(br. d, J 9.2, HÀC(2'), HÀC(6')).

22-(4-Nitrophenyl) Ester 30d: Yield 78.2 mg (74.6%). Colorless oil. R_f(hexane/AcOEt 1 :1) 0.63. ¹H-NMR

(400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.94 (s, Me(19)); 1.06 (s, Me(24)); 1.12 (s, Me(18)); 2.03 (d, J 1.2,

Me(23)); 2.39 (d, J 18.8, 1 HÀC(15)); 2.59 (d, J 18.8, 1 HÀC(15)); 2.94 (ddd, J 2.0, 3.6, 10.4, HÀC(13));

3.04 (s, MeSO₂); 4.35 (dd, J 4.8, 11.2, HÀC(3)); 4.39 (d, J 12.8, 1 HÀC(17)); 4.43 (d, J 12.8, 1 HÀC(17));

6.91 (dd, J 1.2, 10.8, HÀC(20)); 7.32 (br. d, J 9.2, HÀC(3'), HÀC(5')); 8.30 (br. d, J 9.2, HÀC(2'),

HÀC(6')).

22-(3,4,5-Trimethoxyphenyl) Ester 30e: Yield 23.7 mg (21.1%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.50.

¹H-NMR (400 MHz, CDCl₃): 0.89 (s, Me(25)); 0.89 (s, Me(19)); 1.05 (s, Me(24)); 1.05 (s, Me(18)); 2.09 (d, J

1.2, Me(23)); 2.41 (d, J 18.0, 1 HÀC(15)); 2.52 (d, J 18.0, 1 HÀC(15)); 3.03 (m, HÀC(13)); 3.04 (s, MeSO₂);

3.84 (s, MeOÀC(4')); 3.88 (s, MeOÀC(3'), MeOÀC(5')); 4.35 (dd, J 4.4, 11.2, HÀC(3)); 4.37 (d, J 10.4,

1 HÀC(17)); 4.41 (d, J 10.4, 1 HÀC(17)); 5.88 (dd, J 1.2, 11.6, HÀC(20)); 6.36 (br. s, HÀC(2'), HÀC(6')).

22-S-Phenyl Ester 31a: Yield 44.4 mg (44.4%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.36. ¹H-NMR

(400 MHz, CDCl₃): 0.87 (s, Me(25)); 0.93 (s, Me(19)); 1.06 (s, Me(24)); 1.09 (s, Me(18)); 1.96 (d, J 1.2,

Me(23)); 2.04 (d, J 18.0, 1 HÀC(15)); 2.58 (d, J 18.0, 1 HÀC(15)); 2.94 (m, HÀC(13)); 3.04 (s, MeSO₂);

4.34 (dd, J 3.2, 8.0, HÀC(3)); 4.41 (d, J 10.4, 1 HÀC(17)); 4.48 (d, J 10.4, 1 HÀC(17)); 6.62 (dd, J 1.2,

10.4, HÀC(20)); 7.42 (m, 5 H).

1850

Helvetica Chimica Acta Vol. 87 (2004)

N-Phenyl-22-amide 32a: Yield 70.2 mg (72.3%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.43. ¹H-NMR

(400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.92 (s, Me(19)); 1.05 (s, Me(24)); 1.11 (s, Me(18)); 2.00 (d, J 1.6,

Me(23)); 1.99 (d, J 17.2, 1 HÀC(15)); 2.66 (d, J 17.2, 1 HÀC(15)); 2.87 (ddd, J 4.8, 10.8, 12.4, HÀC(13));

3.04 (s, MeSO₂); 4.35 (dd, J 4.8, 11.6, HÀC(3)); 4.42 (d, J 10.4, 1 HÀC(17)); 4.46 (d, J 10.4, 1 HÀC(17));

5.80 (dd, J 1.6, 10.8, HÀC(20)); 7.11 (t, J 4.8, 4.8, HÀC(4')); 7.34 (t, J 4.8, 8.8, HÀC(3'), HÀC(5')); 7.59

(dd, J 0.8, 8.8, HÀC(2'), HÀC(6')).

N-(4-Chlorophenyl)-22-amide 32b: Yield 46.4 mg (45.1%). Colorless oil. R_f(hexane/AcOEt 1:1) 0.37.

¹H-NMR (400 MHz, CDCl₃): 0.89 (s, Me(25)); 0.92 (s, Me(19)); 1.04 (s, Me(24)); 1.10 (s, Me(18)); 1.98 (d, J

1.6, Me(23)); 1.96 (d, J 17.2, 1 HÀC(15)); 2.64 (d, J 17.2, 1 HÀC(15)); 2.87 (ddd, J 4.8, 10.8, 12.4,

HÀC(13)); 3.04 (s, MeSO₂); 4.34 (dd, J 4.2, 12.0, HÀC(3)); 4.42 (d, J 10.0, 1 HÀC(17)); 4.47 (d, J 10.0,

1 HÀC(17)); 5.78 (br. d, J 10.4, HÀC(20)); 7.28 (dd, J 2.0, 8.8, HÀC(3'), HÀC(5')); 7.55 (dd, J 2.0, 8.8,

HÀC(2'), HÀC(6')).

9. (20E)-3-Deoxy-22-secoebelin-2-en-22-oic Acid Lactone 22-Aryl Esters ((2E)-3-{(1'S,2'R,4'aR,4'bS,8'a-

S,10'aR)-3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-Dodecahydro-4'b,8',8',10'a-tetramethyl-5-oxospiro[furan-3(2H),1'(2'H)-

phenanthren]-2'-yl}-2-methylprop-2-enoic Acid Aryl Esters) 33, (20E)-3-Deoxy-22-secoebelin-2-en-22-oic Acid

Lactone 22-S-Aryl Esters ((2E)-3-{(1'S,2'R,4'aR,4'bS,8'aS,10'aR)-3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-Dodeca-

hydro-4'b,8',8',10'a-tetramethyl-5-oxospiro[furan-3(2H),1'(2'H)-phenanthren]-2'-yl}-2-methylprop-2-enethioic

Acid S-Aryl Esters) 34, or (20E)-N-Aryl-3-deoxy-22-secoebelin-2-en-22-amide Lactones ((2E)-N-Aryl-3-

{(1'S,2'R,4'aR,4'bS,8'aS,10'aR)-3',4,4'a,4'b,5,5',8',8'a,9',10',10'a-dodecahydro-4'b,8',8',10'a-tetramethyl-5-oxospir-

o[furan-3(2H),1'(2'H)-phenanthren]-2'-yl}-2-methylprop-2-enamide) 35: General Method. To a soln. of 30, 31,

or 32 (0.1 mmol) in N,N-dimethylacetamide (10 ml), Li₂CO₃(0.5 mmol) was added. The mixture was refluxed

for 0.5 h and cooled to r.t. The suspension was taken up with 1m aq. HCl and extracted with Et₂O, the org. layer

washed with brine, dried (MgSO₄), and evaporated, and the crude product purified by FC (hexane/AcOEt 5 :1):

33, 34, or 35, resp.

22-Phenyl Ester 33a: From 30a, 27.2 mg (57.2%) of 33a. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.61.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.97 (s, Me(19)); 1.10 (s, Me(24)); 1.11 (s, Me(18)); 2.03

(br. s, Me(23)); 2.08 (d, J 18.4, 1 HÀC(15)); 2.56 (d, J 18.4, 1 HÀC(15)); 2.93 (m, HÀC(13)); 4.39 (d, J

10.4, 1 HÀC(17)); 4.49 (d, J 10.4, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 6.81 (br. d, J 10.8,

HÀC(20)); 7.09 (br. d, J 8.0, HÀC(2'), HÀC(6')); 7.24 (t, J 7.6, 7.6, HÀC(4')); 7.37 (t, J 7.6, 8.0, HÀC(3'),

HÀC(5')). ¹³C-NMR (100 MHz, CDCl₃): 13.3 (C(23)); 16.2 (C(19)); 17.3 (C(24)); 18.9 (C(6)); 20.1 (C(11)); 22.6

(C(18)); 28.2 (C(12)); 31.6 (C(25)); 33.1 (C(15)); 34.7 (C(7)); 36.3 (C(10)); 38.6 (C(8)); 40.0 (C(9)); 40.2

(C(4)); 40.8 (C(1)); 51.2 (C(13)); 51.4 (C(14)); 51.8 (C(5)); 69.3 (C(17)); 120.9 (C(2)); 121.7 (C(2'), C(6'); 125.7

(C(4')); 129.3 (C(3'), C(5')); 130.3 (C(21)); 137.9 (C(3)); 142.3 (C(20)); 150.9 (C(1')); 165.9 (C(22)); 176.4

(C(16)). EI-MS: 383 (100, [M À PhO] ), 355 (1), 121 (41), 93 (60).

22-(4-Chlorophenyl) Ester 33b: From 30b, 21.3 mg (41.7%) of 33b. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.50. ¹H-NMR (400 MHz, CDCl₃): 0.90 (s, Me(25)); 0.92 (s, Me(19)); 0.99 (s, Me(24)); 1.13 (s, Me(18)); 2.01

(d, J 1.6, Me(23)); 2.06 (d, J 18.2, 1 HÀC(15)); 2.60 (d, J 18.2, 1 HÀC(15)); 2.97 (m, HÀC(13)); 4.39

(d, J 10.4, 1 HÀC(17)); 4.51 (d, J 10.4, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 6.82 (dd, J 1.6,

10.8, HÀC(20)); 7.07 (br. d, J 8.8, HÀC(2'), HÀC(6')); 7.35 (br. d, J 8.0, HÀC(3'), HÀC(5')).

22-(4-Methoxyphenyl) Ester 33c: From 30c, 37.8 mg (74.7%) of 33c. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.33. ¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.92 (s, Me(19)); 1.01 (s, Me(24)); 1.12 (s, Me(18)); 2.01

(d, J 1.2, Me(23)); 1.98 (d, J 18.2, 1 HÀC(15)); 2.60 (d, J 18.2, 1 HÀC(15)); 2.98 (m, HÀC(13)); 3.81

(s, MeO); 4.42 (d, J 10.4, 1 HÀC(17)); 4.54 (d, J 10.4, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2));

6.30 (dd, J 1.2, 10.4, HÀC(20)); 6.91 (br. d, J 8.2, HÀC(3'), HÀC(5')); 7.02 (br. d, J 8.2, HÀC(2'),

HÀC(6')).

22-(4-Nitrophenyl) Ester 33d: From 30d, 28 mg (53.8%) of 33d. Colorless oil. R_f(hexane/AcOEt 1:1) 0.53.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.93 (s, Me(19)); 0.99 (s, Me(24)); 1.12 (s, Me(18)); 2.03 (d, J

1.2, Me(23)); 2.10 (d, J 18.0, 1 HÀC(15)); 2.66 (d, J 18.0, 1 HÀC(15)); 2.99 (m, HÀC(13)); 4.41 (d, J 10.8,

HÀC(17)); 4.52 (d, J 10.8, HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 6.86 (dd, J 1.2, 10.4,

HÀC(20)); 7.31 (br. d, J 9.2, HÀC(3'), HÀC(5')); 8.28 (br. d, J 9.2, HÀC(2'), HÀC(6')).

22-(3,4,5-Trimethoxyphenyl) Ester 33e: From 30e, 15.6 mg (27.6%) of 33e. Colorless oil. R_f(hexane/AcOEt

1

4 :1) 0.62. H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.89 (s, Me(19)); 0.97 (s, Me(24)); 1.07 (s, Me(18));

2.13 (br. s, Me(23)); 2.65 (d, J 18.2, 1 HÀC(15)); 2.73 (d, J 18.2, 1 HÀC(15)); 3.01 (m, HÀC(13)); 3.80

(s, MeOÀC(4')); 3.82 (s, MeOÀC(3'), MeOÀC(5')); 4.41 (d, J 10.8, 1 HÀC(17)); 4.68 (d, J 10.8,

1 HÀC(17)); 5.41 (m, HÀC(3)); 5.40 (m, HÀC(2)); 6.36 (br. d, J 10.4, HÀC(20)); 6.28 (br. s, HÀC(2'),

HÀC(6')).

Helvetica Chimica Acta Vol. 87 (2004)

1851

22-S-Phenyl Ester 34a: From 31a, 13.4 mg (27.3%) of 34a. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.55.

¹H-NMR (400 MHz, CDCl₃): 0.86 (s, Me(25)); 0.90 (s, Me(19)); 0.98 (s, Me(24)); 1.03 (s, Me(18)); 2.12 (d, J

1.6, Me(23)); 2.36 (d, J 18.0, 1 HÀC(15)); 2.56 (d, J 18.0, 1 HÀC(15)); 3.40 (m, HÀC(13)); 4.32 (d, J 10.4,

1 HÀC(17)); 4.44 (d, J 10.4, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 5.52 (dd, J 1.6, 10.2,

HÀC(20)); 7.45 (m, 5 H).

22-(4-Chlorophenyl) Ester 34b: 42.1 mg (47.0% based on 16) of 34b. Colorless oil. R_f(hexane/AcOEt 4 :1)

0.67. ¹H-NMR (400 MHz, CDCl₃): 0.89 (s, Me(25)); 0.92 (s, Me(19)); 0.97 (s, Me(24)); 1.12 (s, Me(18)); 1.97

(d, J 1.2, Me(23)); 2.56 (d, J 18.2, 1 HÀC(15)); 2.64 (d, J 18.2, 1 HÀC(15)); 2.92 (m, HÀC(13)); 4.42

(d, J 10.8, 1 HÀC(17)); 4.54 (d, J 10.8, 1 HÀC(17)); 5.43 (m, HÀC(3)); 5.44 (m, HÀC(2)); 6.63 (dd, J 1.2,

10.0, HÀC(20)); 7.38 (br. d, J 9.2, HÀC(3'), HÀC(5')); 7.39 (br. d, J 9.2, HÀC(2'), HÀC(6')).

22-S-(4-Methoxyphenyl) Ester 34c: 40.2 mg (44.9% based on 16) of 34c. Colorless oil. R_f(hexane/AcOEt

1

4 :1) 0.33. H-NMR (400 MHz, CDCl₃): 0.92 (s, Me(25)); 0.96 (s, Me(19)); 1.11 (s, Me(24)); 1.13 (s, Me(18));

1.96 (d, J 1.2, Me(23)); 2.08 (d, J 18.2, 1 HÀC(15)); 2.60 (d, J 18.2, 1 HÀC(15)); 2.96 (m, HÀC(13)); 3.84

(s, MeO); 4.41 (d, J 10.4, 1 HÀC(17)); 4.54 (d, J 10.4, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2));

6.63 (dd, J 1.2, 10.4, HÀC(20)); 6.95 (br. d, J 8.8, HÀC(3'), HÀC(5') ); 7.33 (br. d, J 8.8, HÀC(2'),

HÀC(6')).

N-Phenyl-22-amide 35a: From 32a, 24 mg (50.5%) of 35a. Colorless oil. R_f(hexane/AcOEt 4 :1) 0.33.

¹H-NMR (400 MHz, CDCl₃): 0.88 (s, Me(25)); 0.93 (s, Me(19)); 0.99 (s, Me(24)); 1.11 (s, Me(18)); 1.98 (d, J

1.6, Me(23)); 1.98 (d, J 18.2, 1 HÀC(15)); 2.66 (d, J 18.2, 1 HÀC(15)); 2.91 (m, HÀC(13)); 4.42 (d, J 10.8,

1 HÀC(17)); 4.51 (d, J 10.8, 1 HÀC(17)); 5.42 (m, HÀC(3)); 5.43 (m, HÀC(2)); 5.82 (dd, J 1.6, 10.8,

HÀC(20)); 7.10 (t, J 7.6, HÀC(4')); 7.32 (t, J 7.6, 8.4, HÀC(3'), HÀC(5')); 7.33 (br. d, J 8.4, HÀC(2'),

HÀC(6')).

N-(4-Chlorophenyl-22-amide 35b: From 32b, 23.4 mg (45.9%) of 35b. Colorless oil. R_f(hexane/AcOEt

4 :1) 0.37. ¹H-NMR (400 MHz, CDCl₃): 0.87 (s, Me(25)); 0.89 (s, Me(19)); 1.01 (s, Me(24)); 1.14 (s, Me(18));

1.98 (d, J 1.6, Me(23)); 1.98 (d, J 17.2, 1 HÀC(15)); 2.66 (d, J 17.2, 1 HÀC(15)); 2.90 (m, HÀC(13)); 4.42

(d, J 10.4, 1 HÀC(17)); 4.53 (d, J 10.4, 1 HÀC(17)); 5.43 (m, HÀC(3)); 5.45 (m, HÀC(2)); 5.80 (dd, J 1.6,

10.4, HÀC(20)); 7.28 (dd, J 2.0, 6.8, HÀC(3'), HÀC(5') ); 7.56 (dd, J 2.0, 6.8, HÀC(2'), HÀC(6')).

10. (20E)-3-Deoxy-1-oxo-22-secoebelin2-en-22-oic Acid Lactone 22-Aryl Esters ((2E)-3-

{(1'S,2'R,4'aS,4'bS,8'aS,10'aR)-3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-Dodecahydro-4'b,8',8',10'a-tetramethyl-5,5'-di-

oxospiro[furan-3(2H),1'(2'H)-phenanthren]-2'-yl}-2-methylprop-2-enoic Acid Aryl Esters) 8, (20E)-3-Deoxy-1-

oxo-22-secoebelin-2-en-22-oic Acid Lactone 22-S-Aryl Esters ((2E)-3-{(1'S,2'R,4'aS,4'bS,8'aS,10'aR)-

3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-Dodecahydro-4'b,8',8',10'a-tetramethyl-5,5'-dioxospiro[furan-3(2H),1'(2'H)-

phenanthren]-2'-yl}-2-methylprop-2-enethioic Acid S-Aryl Esters) 9, and (20E)-N-Aryl-3-deoxy-1-oxo-22-

secoebelin-2-en-22-amide

Lactones

((2E)-N-Aryl-3-{(1'S,2'R,4'aS,4'bS,8'aS,10'aR)-

3',4,4',4'a,4'b,5,5',8',8'a,9',10',10'a-dodecahydro-4'b,8',8',10'a-tetramethyl-5,5'-dioxospiro[furan-3(2H),1'(2'H)-

phenanthren]-2'-yl}-2-methylprop-2-enamides) 10: General Method. 10.1. To a soln. of 33, 34, or 35

(0.025 mmol) in dioxane (5 ml), CaCO₃(0.14 mmol) and NBS (0.12 mmol) were added. The mixture was

heated at 508 for 6 h under irradiation. After neutralization with 5% aq. HCl soln., the mixture was extracted

with Et₂O and the org. layer washed with H₂O, dried (MgSO₄), and evaporated: yellowish oil C. This crude

product could be used directly in the next step or could be purified by FC (hexane/AcOEt 3 :1): 8, 9, or 10, resp.,

and the by-products 36, 37, or 38, resp.

10.2. To the crude yellowish oil C in dioxane (5 ml), CaCO₃(0.14 mmol) and H₂O (50 ml) were added. The

mixture was refluxed for 5 h. After neutralization with 5% aq. HCl soln., the mixture was extracted with Et₂O

(3 Â 10 ml) and the org. layer washed with H₂O (10 ml), dried (MgSO₄), and evaporated: yellowish oil D.

10.3. To the yellowish oil D in CH₂Cl₂(5 ml), PCC (0.1 mmol) was added and the mixture refluxed for 6 h.

The mixture was diluted with CH₂Cl₂(20 ml), the soln. washed with 10% aq. K₂CO₃soln. and H₂O, dried

(MgSO₄), and evaporated, and the a brown oil purified by FC (SiO₂, hexane/CHCl₃/Me₂CO 15 :5 :1): 8, 9, or 10,

resp.

1

22-Phenyl Ester 8a: From 33a, 4.1 mg (34%) of 8a. Colorless oil. R_f(hexane/AcOEt 3 :1) 0.42. H-NMR

(400 MHz, CDCl₃): 1.10 (s, Me(25)); 1.13 (s, Me(19)); 1.18 (s, Me(24)); 1.24 (s, Me(18)); 2.01 (br. s, Me(23));

2.08 (d, J 18.4, 1 HÀC(15)); 2.56 (d, 18.4, 1 HÀC(15)); 2.98 (m, HÀC(13)); 4.46 (m, 2 HÀC(17)); 5.71

(d, J 10.0, HÀC(2)); 6.34 (m, J 10.0, HÀC(3)); 6.85 (br. d, J 10.8, HÀC(20)); 7.11 (br. d, J 7.6, HÀC(2'),

HÀC(6')); 7.25 (m, HÀC(4')); 7.38 (m, HÀC(3'), HÀC(5')).

22-(4-Chlorophenyl) Ester 8b: 30.2 mg (33.9% based on 16) of 8b. Colorless oil. R_f(hexane/AcOEt 3 :1)

0.42. ¹H-NMR (500 MHz, CDCl₃): 1.07 (s, Me(25)); 1.12 (s, Me(19)); 1.17 (s, Me(24)); 1.22 (s, Me(18)); 2.00

(br. s, Me(23)); 2.08 (d, J 18.4, 1 HÀC(15)); 2.56 (d, J 18.4, 1 HÀC(15)); 2.97 (m, HÀC(13)); 4.41

1852

Helvetica Chimica Acta Vol. 87 (2004)

(br. s, 2 HÀC(17)); 5.69 (d, J 10.1, HÀC(2)); 6.34 (m, J 10.1, HÀC(3)); 6.84 (br. d, J 10.6, HÀC(20)); 7.10

(dd, J 0.4, 8.1, HÀC(2'), HÀC(6')); 7.38 (dd, J 0.4, 8.1, HÀC(3'), HÀC(5')). ESI-MS: 479 [M 1 Na À Cl] ).

22-(4-Methoxyphenyl) Ester 8c: From 33c, 4.2 mg (32.1%) of 8c. Colorless oil. R_f(hexane/AcOEt 1 :1) 0.59.

¹H-NMR (500 MHz, CDCl₃): 1.07 (s, Me(25)); 1.12 (s, Me(19)); 1.16 (s, Me(24)); 1.22 (s, Me(18)); 1.97 (d, J

0.8, Me(23)); 2.06 (d, J 18.4, 1 HÀC(15)); 2.56 (d, J 18.4, 1 HÀC(15)); 2.94 (m, HÀC(13)); 4.48

(m, 2 HÀC(17)); 5.70 (d, J 10.1, HÀC(2)); 6.34 (m, J 10.1, HÀC(3)); 6.64 (dd, J 1.1, 10.3, HÀC(20));

6.93 (dd, J 1.8, 8.7, HÀC(2'), HÀC(6')); 7.32 (dd, J 1.8, 8.7, HÀC(3'), HÀC(5')). ESI-MS: 559.6 ([M K] ).

22-(3,4,5-Trimethoxyphenyl) Ester 8d: 19.1 mg (19.4% based on 16) of 8d. Colorless oil. R_f(hexane/AcOEt

1:1) 0.55. ¹H-NMR (500 MHz, CDCl₃): 1.09 (s, Me(25)); 1.12 (s, Me(19)); 1.17 (s, Me(24)); 1.22 (s, Me(18));

2.03 (d, J 1.1, Me(23)); 2.03 (d, J 18.3, 1 HÀC(15)); 2.56 (d, J 18.3, 1 HÀC(15)); 3.01 (m, HÀC(13)); 3.83

(s, MeOÀC(4')); 3.87 (s, MeOÀC(3'), MeOÀC(5')); 4.47 (br. s, 2 HÀC(17)); 5.70 (d, J 10.1, HÀC(2)); 6.35

(m, J 10.1, HÀC(3)); 6.92 (dd, J 1.0, 10.4, HÀC(20)); 6.60 (br. s, HÀC(2'), HÀC(6')). ¹³C-NMR (100 MHz,

CDCl₃): 13.3 (C(23)); 14.1 (C(19)); 18.0 (C(24)); 18.4 (C(6)); 23.1 (C(11)); 21.8 (C(18)); 28.1 (C(12)); 29.6

(C(25)); 34.7 (C(15)); 33.1 (C(7)); 36.4 (C(10)); 40.1 (C(8)); 40.4 (C(13)); 43.1 (C(9)); 47.5 (C(4)); 50.9 (C(5));

51.4 (C(14)); 56.2 (MeOÀC(4')); 61.1 (MeOÀC(3'), MeOÀC(5'); 69.2 (C(17)); 103.4 (C(2'), C(6')); 124.0

(C(2)); 129.6 (C(21)); 141.4 (C(4')); 143.2(C(20)); 144.6 (C(1')); 152.9 (C(3'), C(5')); 154.7 (C(3)); 165.1

(C(22)); 175.8 (C(16)); 206.2 (C(1)). ESI-MS: 580.4 (10, M ).

22-S-Phenyl Ester 9a: 11.6 mg (13.5% based on 16) of 9a. Colorless oil. R_f(hexane/AcOEt 1:1) 0.60.

¹H-NMR (500 MHz, CDCl₃): 1.09 (s, Me(25)); 1.11 (s, Me(19)); 1.16 (s, Me(24)); 1.23 (s, Me(18)); 1.95 (d, J

1.0, Me(23)); 2.04 (d, J 18.3, 1 HÀC(15)); 2.57 (d, J 18.3, 1 HÀC(15)); 2.98 (m, HÀC(13)); 4.48

(m, 2 HÀC(17)); 5.70 (d, J 10.1, HÀC(2)); 6.34 (m, J 10.1, HÀC(3)); 6.68 (dd, J 1.0, 10.5, HÀC(20));

7.40 7.42 (m, 5 H). ESI-MS: 529 (100, [M Na] ).

22-S-(4-Chlorophenyl) Ester 9b: 19.7 mg (21.5% based on 16) of 9b. Colorless oil. R_f(hexane/AcOEt 1 :1)

0.62. ¹H-NMR (500 MHz, CDCl₃): 1.09 (s, Me(25)); 1.12 (s, Me(19)); 1.16 (s, Me(24)); 1.22 (s, Me(18)); 1.94

(br. s, Me(23)); 1.98 (d, J 18.4, 1 HÀC(15)); 2.58 (d, J 18.4, 1 HÀC(15)); 2.96 (m, HÀC(13)); 4.47

(br. s, 2 HÀC(17)); 5.70 (d, J 10.1, HÀC(2)); 6.34 (m, J 10.1, HÀC(3)); 6.59 (br. d, J 10.3, HÀC(20));

7.33 7.36 (m, 4 H). ¹³C-NMR (100 MHz, CDCl₃): 13.4 (C(23)); 15.7 (C(19)); 17.9 (C(24)); 18.0 (C(6)); 21.8

(C(18)); 23.0 (C(11)); 27.8 (C(12)); 31.0 (C(25)); 32.8 (C(7)); 34.8 (C(15)); 36.3 (C(10)); 39.9 (C(8)); 40.0

(C(13)); 43.1 (C(9)); 47.4 (C(4)); 50.8 (C(5)); 52.3 (C(14)); 69.4 (C(17)); 124.0 (C(2)); 129.2 (C(2'), C(6'));

129.6 (C(21)); 135.8 (C(4')); 136.3 (C(3'), C(5')); 138.4 (C(20)); 141.4 (C(1')); 151.7 (C(3)); 175.9 (C(16)); 191.4

(C(22)); 206.4 (C(1)). ESI-MS: 564.3 ([M 1 Na] ).

22-S-(4-Methoxyphenyl) Ester 9c: From 34c, 8.2 mg (61.0%) of 9c. Colorless oil. R_f(hexane/AcOEt 1 :1)

0.59. ¹H-NMR (500 MHz, CDCl₃): 1.09 (s, Me(25)); 1.12 (s, Me(19)); 1.17 (s, Me(24)); 1.23 (s, Me(18)); 2.06

(br. s, Me(23)); 2.06 (d, J 18.2, 1 HÀC(15)); 2.56 (d, J 18.2, 1 HÀC(15)); 2.94 (m, HÀC(13)); 3.80

(s, MeO); 4.46 (br. s, 2 HÀC(17)); 5.70 (d, J 10.1, HÀC(2)); 6.34 (m, J 10.1, HÀC(3)); 6.82 (br. d, J

10.5, HÀC(20)); 6.88 (br. d, J 8.7, HÀC(3'), HÀC(5')); 7.02 (br. d, J 8.7, HÀC(2'), HÀC(6')). ESI-MS:

538 ([M 2] ).

N-(4-Methoxyphenyl)-22-amide 10a: From 16, 11.5 mg (13.1%) of 10a. Colorless oil. R_f(hexane/AcOEt

1:1) 0.67. ¹H-NMR (500 MHz, CDCl₃): 1.06 (s, Me(25)); 1.09 (s, Me(19)); 1.12 (s, Me(24)); 1.22 (s, Me(18));

2.05 (br. s, Me(23)); 2.51 (d, J 18.2, 1 HÀC(15)); 2.62 (d, J 18.2, 1 HÀC(15)); 2.94 (m, HÀC(13)); 3.82

(s, MeO); 4.35 (br. s, 2 HÀC(17)); 5.66 (d, J 10.2, HÀC(2)); 6.35 (m, J 10.2, HÀC(3)); 6.84 (br. d, J 10.4,

HÀC(20)); 7.47 (m, 4 H). ESI-MS: 543.1 ([M 1 Na] ).

11. AChE Inhibitory Activities. AChE activity was measured spectrophotometrically according to Ellman

et al. [12]. Briefly, to 3 ml of 0.1m phosphate buffer at pH 8.0, 20 ml of 0.075m acetylthiocholine iodide or

chloride (Sigma, U.S.A.) was added, followed by 100 ml of 0.1m 5,5'-dithiobis[2-nitrobenzoic acid] and 10

100 ml of the sample to be tested. At 258, the reaction was started by addition of 20 ml of an AChE (Sigma,

U.S.A.) stock soln. (5 units/ml), and the time course of the enzyme activity was monitored for 3 min.

12. KB Cell Cytotoxicity Assay. KB-Cells survival was determined by the MTT assays [17]. Briefly, the

tetrazolium salt MTT ( 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide; Sigma, St. Louis,

MO, USA) soln. was prepared at 5 mg/ml in phosphate-buffered saline freshly before use. KB Cells were diluted

in fresh complete medium and seeded in 96-well plates (Falcon, Franklin Lakes, NJ, USA) (10⁴cells/well). After

24 h incubation, cells were treated with various concentrations of synthetic compounds for 72 h, then 10 ml of

MTT soln. was added to each well. The plates were then incubated in a CO₂incubator for 4 h. After incubation,

the cells were lysed with DMSO. The plates were analyzed in a multiwell-plate reader (Bio-Tek Instruments,

USA) at 570 nm.

Helvetica Chimica Acta Vol. 87 (2004)

1853

13. Caspase-3 Cleavage Assay. The fluorogenic substrate for caspase-3 (Ac-DEVD-AMC) is labeled with

the fluorochrome 7-amino-4-methyl coumarin ( 7-amino-4-methyl-2H-1-benzopyran-2-one; AMC). The

substrate produces a blue fluorescence that can be detected by exposure to UV light at 360 nm. AMC is released

from these substrates upon cleavage by caspase-3. Free AMC produces a yellow-green fluorescence that could

be monitored in a fluorometer at 460 nm. The amount of yellow-green fluorescence produced upon cleavage is

proportional to the amount of caspase-3 activity [14].

14. Protection of Rat Primary Neurons Against OGD-Induced Injury. Cortical neurons were isolated from

newborn rats and cultured at 378 in a humidified atmosphere containing 5% of CO₂. Cells were seeded at a

density of 2 ¥ 10⁵per ml in phenol red-free RPMI 1640 medium, supplemented with 10% heat-inactivated fetal

bovine serum, penicillin (100 units/ml), and streptomycin (100 mg/ml). Experiments were carried out 10 d after

cells were seeded [18].

For OGD insult, the original media were removed, and the cells were washed with a glucose-free Earle×s

balanced salt soln. (EBSS, pH 7.4, supplemented with penicillin (100 units/ml) and streptomycin (100 mg/ml)).

The cultures were then placed in fresh glucose-free EBSS and held for 6 h in a box containing 95% (v/v) of N₂

and 5% (v/v) of CO₂at 378. Control cultures were maintained for the same interval of time under standard

conditions.

The synthetic compounds were dissolved and diluted in a phosphate-buffered saline (PBS) and were added

into the cultures 2 h before OGD treatment. After OGD for 6 h, cell viability was evaluated by the ability to

reduce MTT, as an indication of metabolic activity. This viability assay was conducted in 96-well plates, and the

formed formazan, the metabolite of MTT, was detected by spectrophotometric measurement at 490 nm in a

microplate reader (Bio-Tek Instruments, U SA).

REFERENCES

[1] E. K. Perry, Br. Med. Bull. 1986, 42, 63; R. T. Bartus, R. L. Dean 3rd, B. Beer, A. S. Lippa, Science

(Washington, D.C.) 1982, 217, 408; W. K. Summers, L. V. Majovski, G. M. Marsh, K. Tachiki, A. Kling, N.

Engl. J. Med. 1986, 315, 1241.

[2] A. Shvaloff, E. Neuman, D. Guez, Psychopharmacol. Bull. 1996, 32, 343; G. K. Wilcock, Neurodegeneration

1996, 5, 505.

[3] K. Otoguro, F. Kuno, S. Omura, Pharmacol. Ther. 1997, 76, 45.

[4] S. Omura, F. Kuno, K. Otoguro, T. Sunazuka, K. Shiomi, R. Masuma, Y. Iwai, J. Antibiot. 1995, 48, 745; F.

Kuno, K. Otoguro, K. Shiomi, Y. Iwai, S. Omura, J. Antibiot. 1996, 49, 742; F. Kuno, K. Shiomi, K. Otoguro,

T. Sunazuka, S. Omura, J. Antibiot. 1996, 49, 748.

[5] J. W. Chen, Y. L. Luo, M.-J. Hwang, J.-C. Peng, K.-H. Ling, J. Biol. Chem. 1999, 274, 34916.

[6] F.-C. Peng, J. Nat. Prod. 1995, 58, 857; F.-C. Peng, J.-S. Cheng, Mycopathologia 1997, 137, 125; F.-C. Peng, J.

Nat. Prod. 1997, 60, 842.

[7] Y. Zhao, Y.-L. Ku, X. J. Hao, S. S. Lee, Tetrahedron 2000, 56, 8901.

[8] J. J. Pappas, W. P. Keaveney, Tetrahedron Lett. 1966, 4273.

[9] Y.-F. Cheung, Tetrahedron Lett. 1979, 3809; I. E. Marko, A. Mekhalfia, Tetrahedron Lett. 1990, 31, 7237.

[10] A. Furlenmeier, A. F¸rst, A. Langemann, G. Waldvogel, P. Hocks, U. Kerb, R. Wiechert, Helv. Chim. Acta

1967, 50, 2387.

[11] B. W. Finucane; J. B. Thomson, J. Chem. Soc., Chem. Commun. 1969, 1220.

[12] G. L. Ellman, K. D. Courtney, V. Andres Jr., R. M. Featherstone, Biochem. Pharmacol. 1961, 7, 88.

[13] J. Harada, M. Sugimoto, Brain Res. 2000, 842, 311.

[14] J. Zhou, X. C. Tang, FEBS Lett. 2002, 526, 21.

[15] M. D×Ambrosio, A. Guerriero, C. Debitus, J. Waikedre, F. Pietra, Tetrahedron Lett. 1997, 38, 6285.

[16] S. Nanduri, S. S. R. Thunuguntla, V. K. Nyavanandi, S. Kasu, P. M. Kumar, P. S. Ram, S. Rajagopal, R. A.

Kumar, D. S. Deevi, R. Rajagopalan, A. Venkateswarlu, Bioorg. Med. Chem. Lett. 2003, 13, 4111.

[17] T. Araki, Y. Enokido, N. Inamura, S. Aizawa, H. Hatanaka, Brain Res. 1998, 794, 239.

[18] K. Abe, R. E. Tanzi, K. Kogure, Neurosci. Lett. 1991, 125, 172; R. N. Kalaria, Neurobiol. Aging, 2000, 21,

321; G. Zhao, P. F. Michael, Neurosci. Lett. 2000, 285, 177; J. Zhou, Y. Fu, X. C. Tang, Neurosci. Lett. 2001,

306, 53.

[19] D. Gupta, R. Soman, S. Dev, Tetrahedron 1982, 38, 3013.

Received January 4, 2004

Article Doi

Synthesis of A/B ring analogs of territrem B and evaluation of their biological activities

DOI: 10.1002/hlca.200490163

Source and publish data:

Authors:

Article abstract of DOI:10.1002/hlca.200490163

Full text of DOI:10.1002/hlca.200490163

Products guided by the article

R&D Labs maybe for 769949-91-9

Relevant to this article

Hot Product