Synthesis and inotropic activity of hydroindene derivatives

Article abstract of DOI:10.1016/S0968-0896(99)00251-5

A synthetic approach to hydroindenic inotropic agents has been developed, starting from enantiopure Hajos-Parrish (1), Hajos-Wiechert (2), and related diketones. Their transformation into C-1 formyl derivatives and other subsequent synthetic targets is described. The results of the thermodynamic equilibration between both epimers of each formyl derivative are analysed. The inotropic activities of selected compounds on right and left atrial preparations are also evaluated and discussed. Copyright (C) 1999 Elsevier Science Ltd.

Full text of DOI:10.1016/S0968-0896(99)00251-5

Bioorganic & Medicinal Chemistry 7 (1999) 2991±3001
Synthesis and Inotropic Activity of Hydroindene Derivativesy
Luis G. Sevillano, a Concepcion P. Melero, a Melchor Boya, a Jose Luis Lopez, a
Fernando Tome, a Esther Caballero, a Rosalõa Carron, b M. Jose Montero, b
Manuel Medarde a,* and Arturo San Feliciano a
a
Â
Laboratorio de Quõmica Organica y Farmaceutica, Facultad de Farmacia, Universidad de Salamanca, Campus `Miguel de Unamuno',
Â
Â
37007 Salamanca, Spain
Laboratorio de Farmacologõa, Facultad de Farmacia, Universidad de Salamanca, Campus `Miguel de Unamuno', 37007 Salamanca,
Spain
b
Â
Accepted 16 August 1999
AbstractÐA synthetic approach to hydroindenic inotropic agents has been developed, starting from enantiopure Hajos±Parrish (1),
Hajos±Wiechert (2), and related diketones. Their transformation into C-1 formyl derivatives and other subsequent synthetic targets
is described. The results of the thermodynamic equilibration between both epimers of each formyl derivative are analysed. The
inotropic activities of selected compounds on right and left atrial preparations are also evaluated and discussed. # 1999 Elsevier
Science Ltd. All rights reserved.
Introduction
moieties of cardenolides. In this way it is possible to
study the structural requirements of the C, D-ring sys-
tem and the minimum size of these molecules to display
cardiotonic activity.
Cardenolides constitute a very interesting and well
known family of steroid glycosides, which have been
used for a long time in the treatment of congestive heart
failure. Among them, digoxin is the drug of election for
this disease, although it has some toxic e€ects that limit
its use. Therefore, a lot of e€ort has been done to design
and synthesise other inotropic agents.1 A great number
of derivatives obtained by chemical transformations of
natural steroids have been assayed, in order to ®nd less
toxic cardiotonic digitalis like compounds.2±4 Non-
steroidal synthetic analogues have also been obtained to
this purpose,5±8 but no de®nitive structure±activity
relationship (SAR) has been deduced.
These ideas had been described in preliminary commu-
nications14±16 and the previous results in the synthesis of
the starting materials17,18 and some derivatives19 have
already been published. To our knowledge, no previous
approaches to cardenolide analogues by using hydro-
indane as the basic skeleton have been reported. Only
recently, a similar approach to those shown in our pre-
vious communications has been applied in the synthesis
of 9,10-secosteroids20 and cyclohexylhydrindanes21 as
digitoxigenin analogues.
Some time ago we started out a research line directed at
the synthesis of new `nonsteroidal' cardenolide analo-
gues. After the preparation of several diterpene9±11 and
cyclohexane12,13 derivatives, lacking the cyclopentane
D-ring, we moved to the synthesis of hydroindane deri-
vatives (Fig. 1), as structural equivalents of the C-D
rings of the steroid skeleton. By this approach it is pos-
sible to prepare a number of derivatives bearing sub-
stituents at positions C-4 and C-5, thus increasing the
molecular size to mimic the A, B rings and the sugar
In this paper we describe the general methodology used
at our laboratory for the synthesis of 3ab-hydroxy and
3a-unsaturated derivatives of hydroindenes, carrying
C-1, C-4, and/or C-5 substituents. The Y moiety at C-1
can be functional groups replacing the butenolide moi-
ety and the Z one can contribute to increasing the size
and/or the solubility of the ®nal products. We have
recently communicated the activity of some of these
compounds,22 which describe the positive inotropic
e€ect displayed by the 3a-unsaturated bis(guanylhy-
drazone) derivative. In the present article we report the
synthesis of some new derivatives, with di€erent sub-
stituents at C-1 and the guanylhydrazone moiety at C-5,
with the aim of assessing their inotropic activity.
* Corresponding author. Tel.:+34-923-294528; fax:+34-923-294515;
ye-mail: medarde@gugu.usal.es
Dedicated to the memory of Professor Joaquõn de Pascual Teresa.
0968-0896/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(99)00251-5

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L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
observed transposition of the double bond from C-3a to
C-231 in the case of 800. When lower temperatures were
used ( 78ꢀC), the reaction proved to be chemoselective
towards the C-5 derivative 8. In the case of the methyl
derivative 4, the reaction only worked under conditions,
which led to the C-1 protected product 100, without any
detectable amount of 10. In consequence, for unsatu-
rated ketones 2 and 4, it seemed that kinetic control
produces C-5 protected derivatives, increasing C-1 pro-
tected products with temperature. As the reaction rate
at C-5 decreases by the presence of the methyl at C-4 in
4, a higher temperature is required for the process to
work, thus yielding the thermodynamic product 100. In
the case of 9, the higher reactivity of 1,3-propanedithiol
facilitates the formation of the C-5 protected 1,3-
dithiane derivative 9 in good yield (Scheme 2).
Figure 1. Structural comparison between cardenolides and projected
hydroindenic inotropic agents.
Methods and Results
The transformation of protected ketones 5±9 into the
formyl derivatives could be achieved by direct approa-
ches, as methoxymethylenation-hydrolysis or by TOS-
MIC cyanation followed by DIBALH reduction, but
those compounds showed a low reactivity, especially in
the case of 3a-hydroxy derivatives 5±7. Well known
reactions for their utility with sterically hindered
ketones, as the Peterson ole®nation and the reaction
with 2-lithium-2-trimethylsilyl-1,3-dithiane, also failed
to introduce one carbon fragment at the C-1 of those
hydroxyketones. The one carbon elongation at C-1 was
carried out32 by following the Conia procedure33,34 for
the Wittig reaction and the methylenation of these
hydroindane derivatives was then achieved in high yield
(80%) to give 11±15.32
For the obtention of compounds with the hydroindane
skeleton, we decided to start from available enantiopure
materials with this skeleton and carry out their trans-
formation into the target molecules. According to the
retrosynthetic analysis depicted in Scheme 1, the C-1
formyl derivatives are intermediates of interest for our
synthesis.
Starting from the easily available Hajos±Parrish ketone
(1),23,24 the dehydrated Hajos±Wiechert ketone (2),25 or
the 4-methyl derivative 3,26 and due to the higher reac-
tivity of the C-5 keto group in these diketones, it was
necessary for its protection to produce selective trans-
formations of the C-1 keto group. Transformation of 1
or 3 into their dioxolane and dithiane derivatives by
standard procedures27,28 allowed us to obtain com-
pounds 5±7 without any detectable amount of the C-1
protected products.19 On the other hand, for unsatu-
rated diketones 2 or 4 the selective protection of C-5
showed to be very variable depending on the structure
and the reagent used. The selective protection of dike-
tone 2 as the dithiane resulted favourable at position C-
5, yielding 9. The use of bis(trimethylsilyloxy)ethane29,30
with diketone 2 for its protection as a dioxolane deri-
vative, at 50ꢀC, produced a mixture of 80 and 800, pro-
tected at C-1 and C-5 positions, respectively, having
The conversion into the formyl compounds at C-1 was
brought about by hydroboration±oxydation of 11±15 to
16±20(a,b), followed by PCC oxidation to 21±25(a,b).
The hydroboration±oxidation sequence produced the
stereoisomeric alcohols b (16b±20b) and a (16a±20a)
with very di€erent ratios depending on the presence of a
hydroxyl group or double bond at C-3a. Among the 3a-
hydroxy derivatives the compound that displayed the
most stereoselective outcome was 12, resulting 17, in a
ratio a:b 3:7. The dioxolane derivatives 11 and 13, pro-
duced equimolecular amounts of both stereoisomers
16a,b and 18a,b. In the case of unsaturated compounds
14 and 15, the reaction with BBN-oxidation was almost
stereospeci®c, being the b:a ratio in the crude reaction
product 12:1 and 21:1, respectively. When the protected
derivative 14 was used, the reaction took place with
hydrolysis of the dioxolane group, thus yielding hydroxy-
ketones 19a,b (Scheme 3).
In order to know the preferred conformation for each
starting ole®n 11±15 and to correlate the accessibility of
the double bond with the stereochemical outcome of the
hydroboration±oxidation process, molecular mechanics
calculations were carried out.35 The hydroindenes show
three preferred conformations A-B-C (Fig. 2) depending
on the substituents at C-1, C-4, and C-5 for the 3a-hy-
droxy derivatives, while the 3a-unsaturated compounds
have less conformational freedom, due to the presence
of the double bond close to the ring junction, thus having
D as the preferred spatial disposition. The calculated
Scheme 1. Retrosynthetic analysis for planned hydroindenes.

L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
2993
ꢀ
.
Scheme 2. Reagents and conditions: (a) HO(CH2)2OH, BF3 OEt2 or TMSO(CH2)2OTMS, TMSOTf, CH2Cl2, 50 C or HS(CH2)3SH, BF3 OEt2, rt.
.
Scheme 3. Reagents and conditions: (a) (C6H5)3P+CH3 I , NaOtAm, C6H6, re¯ux; (b) 1. BH3/THF or 9-BBN, rt; 2. H2O2, NaOH, EtOH, 50ꢀC;
(c) CCP, CH2Cl2, rt; (d) KOH/ EtOH 5%, rt.
conformations are also in agreement with NMR
experimental results and data, as they are: (a) the NOE
observed at H4b upon irradiation of the C7a-methyl
group for preferred A conformations and (b) the 13C
NMR shift of the C7a-methyl, signal which appears at
<18 ppm when it is in axial disposition (A conforma-
tion) and >20 ppm when it is equatorially disposed (B
conformation).
due to the steric e€ect produced by the 4a-methyl on the
rest of the skeleton in conformations B or C; ®nally,
compounds 14 and 15 both display the D conformation
(Fig. 3). The exocyclic double bond at C-1 shows no
di€erences for accessibility of the hydroborating agent
in the case of compounds with preferred A or B con-
formations, in agreement with the experimental data for
hydroboration-oxidation of 11±13. For the unsaturated
derivatives 14 and 15, the high a-stereoselective attack is
justi®ed by the accessibility of the reagent from this face
of the double bond in conformation D.
Compounds 11 and 12 show a preferred B conformation.
Methyl derivative 13 has A as a preferred conformation

2994
L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
communication.17 Thus, equilibration of compounds
21±25 in basic media produced the desired 1b-CHO
epimers as major equilibration products. By this meth-
odology, the required aldehydes 21b±25b were prepared
by oxidation of the corresponding beta alcohols or
through oxidation±epimerisation processes starting
from the epimeric alpha alcohols.
Figure 2. Preferred conformations for hydroindenes.
Since only the b-stereochemistry of the formyl group at
C-1, obtained by this methodology, maintains the same
relative stereochemistry at C-1 and C-7a as the natural
cardenolides, compounds with type (b) structures are
adequate to prepare hydroindene analogues of carde-
nolides. As a consequence, it would be desirable that a-
formyl derivatives 21a±25a could be transformed into
the b-formyl derivatives 21b±25b. In order to know the
relative stability of both C-1 epimers in compounds 21±
25, theoretical calculations were carried out with these
and other related structures.36 The stability of the C-1-
formyl b-isomers (b) is higher than that of C-1-formyl a-
isomers (a) for the 3a-unsaturated derivatives 24 and 25
as well as for 3a-hydroxy derivatives 21±23, although
for other derivatives it depends on the substituents
at position C-5. Calculations of heats of formation
of compounds 23a and 23b gave ÁH(b)-ÁH(a)=
0.68 kcal/mol, thus favouring the desired b-epimer.
Similar calculations for 24a and 24b and for 25a and
25b also gave negative values for ÁH(b)-ÁH(a)=
0.8 kcal/mol and higher di€erences were observed for
21 and 22, as it was pointed out in our preliminary
These formyl derivatives were used as synthetic inter-
mediates for the preparation of some ®nal products,
carrying at C-1 unsaturated moieties, which usually
confer inotropic activity when placed on a steroidal
framework, as described in the literature.1±4 By Wittig
ole®nation of the aldehyde at C-9 with di€erent ylides
or by condensation with nitromethane, hydroxylamine,
or aminoguanidine, followed by deprotection, reduc-
tion, or treatment of the C-5 keto group with amino-
guanidine, di€erent hydroindenic cardenolide analogues
26±41 have been obtained (Fig. 4). Other derivatives,
carrying less elaborated chains at C-1, as the hydroxy-
methyl derivative 42, have also been prepared, to be
tested as inotropic agents.
Inotropic activity
Compounds 35, 41 and 42 were selected for testing by
virtue of their structural complementarity and di€er-
ences with respect to those other indene derivatives
previously evaluated22 in order to perform a broader
Figure 3. Preferred conformations of compounds 11±15, from MM calculations and NMR data.
Figure 4. Synthesized molecules with hydroindene skeleton.

L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
2995
Figure 5. Cumulative concentration±response e€ect of compounds 35, 41 and 42 on isolated guinea pig left (A) and right (B) atria contractile force.
Each value represents the mean of at least ®ve experiments. Vertical lines show ‹SEM. à indicates p<0.05 when compared with the corresponding
control values.
analysis of the structure±activity relationships within
this family of compounds. They have been evaluated on
isolated guinea pig right and left atria. Right atria show
spontaneous beating, and are used to evaluate the e€ect
of the compounds tested on the contraction force and
cardiac rhythm. Electrically stimulated left atria are
used to evaluate the e€ect on the contractile force.
Simultaneous studies are carried out with the solvent
(DMSO) to con®rm that the parameters checked are not
in¯uenced in none of the preparations.
Comparatively, the nitrovinyl derivative 35 displays
inotropic pro®le and potency similar to those of its 1,5-
bis(guanylhydrazone) analogue previously reported,22
thus reinforcing the presence in this type of compounds
of a Á3a double bond, rather than the 3a-OH group
equivalent to that at C-14 in cardenolides, as an impor-
tant structural factor for positive inotropic activity. On
the other hand, the existence of that double bond toge-
ther with the guanylhydrazone moiety at position C-5
does not constitute a structural guarantee for positive
inotropic activity. The function at position C-1 is also
very important, as it is proven with the carboxylate
derivative 41, the hydroxymethyl derivative 42 and
other compounds previously reported.22 Nevertheless,
the number of compounds assayed and the results
obtained are still low to permit SAR generalisations. To
complement these studies, more speci®c evaluations on
Na+, K+-ATPase inhibition by these and other com-
pounds of the series are currently being studied.
The e€ect of these compounds on the left atria contractile
force has been represented in Figure 5. Compound 41
shows
dependent, on left atria, being signi®cant at 10
a negative inotropic e€ect, concentration-
7
M
dose and showing a maximum of 68% at the highest
4
concentration tested (3Â10 M). Compound 42 also
produces a negative inotropic e€ect, less potent than 41,
at doses higher than 10 5 M, reaching a maximum value
of 46.6% at the same concentration. Similarly both
compounds display light negative inotropic e€ect on
right atria, which is more potent for 41.
In conclusion, we have established a synthetic metho-
dology for the preparation of a variety of 1,5-di-
substituted hydroindenes, and it can be stated that the
dihydroindene structure constitutes, up to the date, the
simplest homocyclic skeletal base for the construction of
either cardiotonics or negative inotropic agents.
Compound 35 shows a di€erent pattern of activity, with
a biphasic e€ect. At low doses (10 7±10 5 M) it displays
a negative inotropic e€ect, similar (left atria) or slightly
more pronounced (right atria) than those observed for
5
compounds 41 and 42, with a maximum of 50% at 10
5
M (Fig. 5). At concentrations higher than 10 M that
Experimental
e€ect begin to be reversed, turning towards a fair posi-
tive inotropic e€ect, which raises to maximum values of
128% on left atria and 75% on right atria, at the max-
General. Melting points were determined on a Buchi 510
instrument and are uncorrected. 1H NMR and 13C
NMR were recorded on a 200 MHz (Bruker WP200SY)
and 400 MHz (Bruker SY) spectrometer, using CDCl3
as solvent with TMS as internal standard. IR spectra
were obtained in CH2Cl2 ®lm in a Nicolet (Impact 410)
spectrophotometer. GC±MS analyses were carried out
with a Hewlett±Packard 5890 Serie II apparatus (70 eV).
4
imum assayed concentration (3Â10
M). This fact
implies the existence of two di€erent mechanisms of
interaction of the compound with the organ, one indu-
cing relaxation and other, opposed and made evident at
higher doses, that enhances the contractile force. None
of the three compounds modi®es signi®cantly the car-
diac beating rate.

2996
L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
For FABHRMS analyses, a VG-TS250 apparatus (70 eV)
was used. Optical rotations were measured at 20ꢀC on a
digital polarimeter. Column chromathography was per-
formed over silica gel Merck (0.063±0.2 or 0.040±
0.063 mm). TLC was performed on precoated silica gel
polyester plates (0.25 mm thickness) with ¯uorescent
indicator UV 254 (Polychrom SI F254).
(7aS)-1,1-Ethylenedioxy-7a-methyl-2,3,5,6,7,7a-hexa-
hydro-1H-inden-5-one (80) and (7aS)-5,5-ethylenedioxy-
7a-methyl-2,4,5,6,7,7a-hexahydro-1H-inden-1-one (800).
To a cooled solution ( 50ꢀC) of diketone 2 (500 mg,
3.05 mmol) in dry CH2Cl2 (10 mL), 1,2-bis(trimethyl-
silyloxy)ethane (0.60 mL, 2.36 mmol) and trimethylsilyl
tri¯ate (60 mL, 0.3 mmol) were added. The reaction was
maintained at 50ꢀC for 24 h. After that time, it was
worked up as usual. After chromatography (hexane:
EtOAc, 3:1), 80 (yellow oil, 203 mg, 32%), 800 (white
solid, 116 mg, 18%) and starting material (220 mg,
44%) were obtained.
(7aS)-5,5-Ethylenedioxy-7a-methyl-2,3,5,6,7,7a-hexahydro-
1H-inden-1-one (8). To a cooled solution ( 78ꢀC) of
diketone 2 (100 mg, 0.61 mmol) in dry CH2Cl2 (0.4 mL),
1,2-bis(trimethylsilyloxy)ethane (0.17 mL, 0.67 mmol)
and trimethylsilyl tri¯ate (10 mL, 0.05 mmol) were
added. The reaction was kept at 78ꢀC for 24 h and
then quenched with pyridine. The mixture was poured
into a saturated sodium bicarbonate solution, diluted
with CH2Cl2, washed with brine and dried to obtain 8
(120 mg, 95%) as a white solid.
80. [a]d 4.0ꢀ (c 0.73, CHCl3). IR: 1692, 1651, 1087, 951
1
cm 1. H NMR (CDCl3) d 1.28 (s, 3H, H8), 1.55±2.85
(m, 8H), 3.87±4.03 (m, 4H, OCH2), 5.80 (dd, 1H, J1=
J2=1.8, H4). 13C NMR (see Table 1). MS m/z (%): 208
(M+, 81), 86 (100).
8. Mp: 87ꢀC (CH2Cl2). [a]d +148.9ꢀ (c 0.26, CHCl3).
800. [a]d +106.3ꢀ (c 0.51, CHCl3). IR: 1743, 1655, 1095,
859 cm 1. 1H NMR (CDCl3) d 1.19 (s, 3H, H8), 1.4±3.2
(m, 8H), 3.9±4.0 (m, 4H, OCH2), 5.71 (d, 1H, J=1.8,
H3). 13C NMR (see Table 1). MS m/z (%): 208 (M+, 6),
99 (100).
1
IR: 1744, 1728, 1647, 866 cm 1. H NMR (CDCl3) d
1.17 (s, 3H, H8), 1.55±2.80 (m, 8H), 3.81±4.10 (m, 4H,
OCH2), 5.49 (d, 1H, J=1.1, H4). 13C NMR (see Table
1). MS m/z (%): 164 (M+ C2H4O2, 89), 79 (100).
Table 1. 13C NMR data for compounds 8±42
C-1
C-2
C-3
C-3a
C-4
C-5
C-6
30.2
C-7
28.3
C-7a
48.1
C-8
20.3
C-9
X
X
X
X
Y
Y
Y
8
218.6
117.3
220.6
117.7
159.2
52.4
53.0
61.8
62.5
44.5
49.6
44.4
45.1
44.8
47.9
45.4
49.3
45.7
47.6
41.1
51.2
41.5
36.7
48.5
47.7
53.3
49.8
50.6
48.1
53.4
53.4
54.0
36.5
31.5
41.5 118.0
26.3
26.6
149.1 120.9 106.4
174.2 123.0 198.7
145.5
166.9 128.5 198.3
154.5 117.4 106.9
179.5 121.5 199.9
152.8 119.2
175.7 122.0 198.3
150.7 120.1 48.7
81.3
84.0
81.7
80.7
81.3
80.9
81.2
84.1
81.3
82.2
81.1
64.5 64.9
65.5 64.5
64.3 64.7
80
32.9
30.7
32.9
32.9
33.4
33.6
33.0
33.3
30.1
36.6
30.3
28.3
26.4
25.6
30.1
36.7
26.6
29.8
30.1
29.6
29.9
30.3
31.0
31.6
28.6
31.2
30.6
33.3
33.2
28.6
29.4
26.4
29.5
26.4
29.5
36.0
33.8
35.7
33.3
28.3
33.8
29.4
25.3
29.3
25.2
28.0
32.8
28.8
27.7
28.4
34.4
28.6
29.2
32.4
35.8
33.5
34.4
36.1
34.8
34.8
33.4
35.7
47.6
49.9
47.3
44.2
44.1
43.0
45.4
44.8
46.9
47.6
46.5
47.3
46.6
47.4
46.6
46.7
45.3
48.9
47.1
41.1
46.0
46.8
49.5
48.1
45.8
54.4
54.3
47.0
46.1
45.6
44.4
19.8
19.0
10.4
25.2
16.4
17.9
18.1
19.6
17.8
16.3
17.6
18.1
17.3
17.1
17.6
16.6
17.2
16.9
17.9
18.0
17.8
17.8
17.5
16.1
17.5
17.1
18.3
16.9
17.3
17.5
16.9
64.7
65.6
65.6
800
37.5 108.8
100
14
31.5
30.9
24.7
24.5
21.1
20.6
24.0
26.0
24.4
24.4
24.5
24.7
24.9
26.6
25.4
25.2
23.9
22.5
22.6
22.1
23.8
25.7
21.8
24.8
25.2
28.0
26.4
22.5
23.0
25.6
28.4
29.1
27.9
28.5
27.6
35.5
37.9
37.8
36.2
37.5
36.1
35.4
38.0
37.5
35.2
35.4
27.7
35.3
35.6
36.8
38.3
24.7
38.0
37.1
29.5
29.1
26.7
26.0
20.1
64.7
104.0
62.8
63.9
202.2
203.6
19b
20b
24b
25b
26b
27b
28a
28b
29a
29b
30b
31b
33b
34a
34b
35ba
360
3600
37aa
37ba
38bb
39aa
39ba
40a
40b
41b
42b
49.0
26.5 24.9 27.6
26.4 24.8 27.6
64.6 64.2
41.9 109.0
50.5 209.9
44.3
39.7
40.3
38.2
42.0 109.3
51.0 210.8
40.6
149.6 131.8 216.1 27.0
150.3 131.2 198.7 27.0
149.8 131.8 198.5 27.2
150.2 131.8 198.7 27.0
149.2 131.7 198.2 27.0 170.4 21.3
150.8 131.2 198.5 26.7 169.7 21.3
128.0 124.8
128.1 125.1
127.7 125.1
143.9 139.6
144.1 139.6
142.6 141.7
153.6
67.3
67.6
70.3
70.6
15.1
15.2
15.1
64.5 64.1
70.7
170.5 21.5
64.4 63.6
64.4 64.3
155.3
64.2 64.2
64.5 64.5
65.4 65.4
64.6 64.6
155.8c
42.0 108.4
41.7 108.8
157.3 119.5 163.7
81.2
81.2
82.9
83.9
41.7 109.2
41.7 109.2
42.7 110.1
40.9 110.1
154.3
156.2 156.5
157.8 158.6
154.2 155.4c
156.8 156.5c
157.5 156.5c
148.3 122.0 166.5 51.3
147.0 122.9 166.6 51.7
147.7 122.5 166.6 51.6 154.1
63.4 156.1
166.1 117.2 157.8
83.2
83.7
177.4 121.7 199.2
176.8 122.2 198.9
163.2 118.2 156.2
166.5 118.5 157.2
44.0 160.4
37.5 160.4
157.2
157.2c
a
Solvent: CD3OD.
Solvent: D2O.
Interchangeable signals.
b
c

L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
2997
(7aS)-1,1-Ethylenedioxy-4,7a-dimethyl-2,3,5,6,7,7a-hexa-
hydro-1H-inden-5-one (100). To
cooled solution
( 50ꢀC) of diketone 4 (1.07 g, 6.0 mmol) in dry CH2Cl2
(21 mL), 1,2-bis(trimethylsilyloxy)ethane (4.5 mL,
18 mmol) and trimethylsilyl tri¯ate (0.4 mL, 1.8 mmol)
were added. The reaction was kept at 20ꢀC for 60 h
under argon. After this period, it was worked up as
usual, obtaining 100 (1.2 g, 91%).
(7aR)-1-Hydroxymethyl-7a-methyl-2,3,5,6,7,7a-hexa-
hydro-1H-inden-5-one propylenic thioacetal (20). The
reaction was carried out under the same conditions as
for the compound 19. From 15 (917mg, 3.64mmol), after
chromatography (hexane:EtOAc, 3:1), a mixture 21:1 of
20b and 20a (820mg, 84%) was obtained as a white solid.
a
20b. [a]d+65.8ꢀ (c 0.33, CHCl3). IR: 3417, 1665,
1
1033 cm 1. H NMR (400 MHz) (CDCl3) d 0.92 (s, 3H,
100. [a]d 18.6ꢀ (c 1.45, CHCl3). IR: 1662, 1156, 1073
H8), 1.3±1.5 (m, 2H, H2 and OH), 1.67 (dt, 1H, J1=13.5
and J2=3.0, H7), 1.71±1.99 (m, 4H, H1, H2, H7 and
Hdithiane), 1.99±2.08 (m, 1H, Hdithiane), 2.15 (dt, 1H,
J1=14.0, J2=3.0, H6), 2.26 (dddd, 1H, J1=17.0,
J2=9.4, J3=6.7 and J4=1.8, H3), 2.43±2.55 (m, 2H, H3
and H6), 2.72 (ddd, 1H, J1=14.0, J2=6.2 and J3=3.0,
Hdithiane), 2.82 (ddd, 1H, J1=14.0, J2=6.2 and J3=3.0,
Hdithiane), 2.93 (ddd, 1H, J1= 14.0, J2=10.5 and
J3=3.0, Hdithiane), 3.00 (ddd, 1H, J1=14.0, J2=10.5
and J3=3.0, Hdithiane), 3.63 (dd, 1H, J1=10.7 and
J2=7.1, H9), 3.73 (dd, 1H, J1=10.7 and J2=7.1, H9),
5.45 (d, 1H, J=1.9, H4). 13C NMR (see Table 1). MS
m/z (%): 270 (M+, 94), 196 (100).
1
cm 1. H NMR (CDCl3) d 1.25 (s, 3H, H8), 1.5±2.7 (m,
8H), 1.69 (s, 3H, H9), 3.85±4.03 (m, 4H, OCH2). 13C
NMR (see Table 1). MS m/z (%): 222 (M+, 37), 86
(100).
(7aR)-7a-Methyl-1-methylene-2,3,5,6,7,7a-hexahydro-
1H-inden-5-one ethylenic acetal (14). To a suspension
of methyltriphenylphosphonium iodide (509 mg,
1.26 mmol) in dry benzene (4 mL), a solution of
tAmONa 4.5N (1.3 mmol) in benzene, diluted with dry
benzene (4 mL) was added at room temperature, being
immediately formed the bright-yellow phosphorane.
The mixture was heated to re¯ux and a solution of 8
(210 mg, 1.01 mmol) in dry benzene (1.5 mL) was added.
After 1 h at re¯ux, it was cooled and ®ltered; the solu-
tion was extracted with EtOAc and washed with brine.
The product was puri®ed by ¯ash chromatography
(hexane:EtOAc, 9:1+1% of Et3N) to yield 14 as a col-
ourless oil (120 mg, 58%).
(1S,7aR)-7a-Methyl-5-oxo-2,3,5,6,7,7a-hexahydro-1H-
inden-1-carbaldehyde (24b). To a suspension of pyr-
idinium chlorochromate (199 mg, 0.93 mmol) and 4 A
molecular sieves (110 mg) in dry CH2Cl2 (31 mL), a
solution of 19b (111 mg, 0.62 mmol) in CH2Cl2 (13 mL)
was added under argon. It was stirred at room tem-
perature for 2 h. Later, the mixture was passed through
a silica gel column (hexane:EtOAc, 1:2) obtaining 24b
(86 mg, 78%) as a white solid.
14. [a]d+175.2ꢀ (c 0.82, CHCl3). IR: 1669, 1075,
1
885 cm 1. H NMR (CDCl3) d 1.12 (s, 3H, H8), 1.60±
2.80 (m, 8H), 3.81±4.10 (m, 4H, OCH2), 4.74 (t, 1H,
J=1.8, H9), 4.79 (t, 1H, J=1.8, H9), 5.27 (s, 1H, H4).
13C NMR (see Table 1).
24b. [a]d+158.9ꢀ (c 0.64, CHCl3). IR: 2740, 1727, 1647,
1
1634 cm 1. H NMR (CDCl3) d 1.19 (s, 3H, H8), 1.90±
3.00 (m, 8H), 5.79 (d, 1H, J=1.5, H4), 9.87 (d, 1H,
J=1.8, H9). 13C NMR (see Table 1). MS m/z (%): 178
(M+, 7), 121 (100).
(7aR)-1-Hydroxymethyl-7a-methyl-2,3,5,6,7,7a-hexahydro-
1H-inden-5-one (19). To a solution of 9-BBN (170 mg,
1.40 mmol) in dry THF (2.2 mL), a solution of 14
(106 mg, 0.51 mmol) in dry THF (1.6 mL) was added at
room temperature under argon. The resulting solution
was stirred for 1 h and 10 min. After that time, it was
cooled to 0ꢀC; ethanol (2 mL), NaOH 6 N (0.65 mL,
3.9 mmol) and 30% H2O2 (0.35 mL, 3.1 mmol) were
sequentially added. The mixture was heated to 50ꢀC for
1 h, and then was allowed to reach room temperature,
diluted with EtOAc, washed with brine and dried to
obtain 260 mg of an oil that was chromatographed on
silica gel column (hexane:EtOAc, 1:1) yielding 19b as a
yellow oil (53 mg, 58%) and 19a (5 mg) along with some
impurities.
(1S,7aR)-7a-Methyl-5,5-propylenedithio-2,3,5,6,7,7a-hexa-
hydro-1H-indene-1-carbaldehyde (25b). Using the same
procedure as for compound 24b, from 20b (520 mg,
1.93 mmol), after the chromatographic column (hexane:
EtOAc, 3:1), 25b (white solid, 250 mg, 48%), 20b
(30 mg, 6%) and sulfoxide-aldehyde (80 mg, 15%) were
obtained.
25b. Mp: 119ꢀC (CHCl3). [a]d +184.8ꢀ (c 1.04, CHCl3).
1
IR: 2753, 1716 cm 1. H NMR (CDCl3) d 1.02 (s, 3H,
H8), 1.70±3.20 (m, 14H), 5.50 (dd, 1H, J1=3.7 and
J2=1.5, H4), 9.83 (d, 1H, J=1.8, H9). 13C NMR (see
Table 1). MS m/z (%): 268 (M+, 100).
19b. [a]d+67.1ꢀ (c 0.55, CHCl3). IR: 3416, 1649,
1
1078 cm 1. H NMR (400 MHz) (CDCl3) d 1.05 (s, 3H,
Epimerization of aldehyde 25. To a 5% KOH/EtOH
solution (2 mL), a mixture 18:1 of aldehydes 25b/25a
(50 mg, 0.19 mmol) was added. The resultant solution
was stirred at room temperature for 1.5 h and then
extracted with CH2Cl2, washed with brine, dried and
evaporated to obtain a mixture 7.7:1 of aldehydes
25b:25a (48 mg, 96%).
H8), 1.47±1.63 (m, 1H, H2), 1.82 (dt, 1H, J1=13.8 and
J2=5.0, H7), 1.85±1.95 (m, 1H, H1), 1.90±2.00 (m, 1H,
H2), 2.17 (ddd, 1H, J1=13.8, J2=5.3 and J3=2.0, H7),
2.30 (dddd, 1H, J1=18.7, J2=5.0, J3=1.3 and J4=0.7,
H6), 2.35±2.55 (m, 2H, H3 and H6), 2.66 (ddt, 1H,
J1=20.0, J2=10.9, and J3=2.8, H3), 3.67 (dd, 1H,
J1=10.7 and J2=7.0, H9), 3.74 (dd, 1H, J1=10.7 and
J2=7.0, H9), 5.72 (s, 1H, H4). 13C NMR (see Table 1).
MS m/z (%): 180 (M+, 17), 121 (100).
4-[(1R,3aS,7aR)-5,5-Ethylenedioxy-3a-hydroxy-7a-meth-
ylperhydroinden-1-yl]-3E-buten-2-one (26b). A solution

2998
L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
of aldehyde 21b (270 mg, 1.12 mmol) and acetonyliden-
triphenylphosphorane (752 mg, 2.36 mmol) in dry ben-
zene (4.8 mL) was stirred at re¯ux under argon for 4.5 h.
The crude product was chromatographed on a silica gel
column (hexane:EtOAc 8:2) to obtain 26b (275 mg,
93%).
1.72 (dd, 1H, J1=13.6 and J2=11.0, H4), 1.90 (ddd, 1H,
J1=13.6, J2=4.0 and J3=2.2, H4), 2.04 (s, 3H,
CH3COO), 2.25 (s, 3H, CH3CO), 2.83 (q, 1H, J=8.4,
H1), 4.95 (tt, 1H, J1=10.5 and J2=4.4, H5), 6.02 (d, 1H,
J=15.8, H10), 6.74 (dd, 1H, J1=15.8 and J2=8.2, H9).
13C NMR (see Table 1).
26b. Mp: 75ꢀC (hexane). [a]d +0.27ꢀ (c 1.00, CHCl3).
(1R,3aS,5S,7aR)-3a-Hydroxy-7a-methyl-1-(3-oxo-1E-
butenyl)perhydroinden-5-yl acetate (29b). The reaction
was carried out under the previously described condi-
tions. From 28b (25 mg, 0.11 mmol), 29b (28 mg, 95%)
was obtained.
1
IR: 3450, 1680, 1625, 1180 cm 1. H NMR (CDCl3) d
0.86 (s, 3H, H8), 2.27 (s, 3H, CH3CO), 2.76 (q, 1H,
J=8.0, H1), 3.98 (s, 4H, OCH2), 5.99 (d, 1H, J=16.0,
H10), 6.71 (dd, 1H, J1=16.0 and J2=8.0, H9). 13C
NMR (see Table 1). MS m/z (%): 280 (M+, 1), 262
(M+ H2O), 99 (100).
29b. [a]d 111ꢀ (c 0.70, CHCl3). IR: 3450, 1725, 1680,
1
1625, 1165 cm 1. H NMR (CDCl3) d 0.91 (s, 3H, H8 ),
(1R,3aS,7aR)-3a-Hydroxy-7a-methyl-1-(3-oxo-1E-buten-
yl)perhydroinden-5-one (27b).
1.36 (ddd, 1H, J1=14.4, J2=6.8 and J3=4.8), 1.50
(ddd, 1H, J1=14.8, J2=14.4 and J3=9.6), 1.76 (dd, 1H,
J1=14.4 and J2=6.0, H4), 1.96 (dd, 1H, J1=14.4,
J2=4.2, H4) 2.08 (s, 3H, CH3COO), 2.26 (s, 3H,
CH3CO), 2.59 (q, 1H, J=7.2, H1), 5.04 (tt, 2H, J1=6.2
and J2=4.2, H5), 5.96 (d, 1H, J=15.8, H10), 6.82 (dd,
1H, J1=15.8 and J2=9.0, H9). 13C NMR (see Table 1).
A
solution of 26b
(170 mg, 0.64 mmol) in AcOH:H2O, 4:1, (10 mL) was
stirred at room temperature for 9 h. The crude product
was neutralised with NaHCO3, extracted with CH2Cl2
and washed with brine. The extract was dried and eva-
porated to obtain compound 27b (135 mg, 95%).
1
27b. IR: 3400, 1710, 1665, 1620, 1150 cm 1. H NMR
(1R,3aS,7aR)-3a-Hydroxy-7a-methyl-1-[(E)-methylthio-
vinyl]perhydroinden-5-one ethylenic acetal (30b). To
CH3SCH2PO(OEt)2 (0.29 mL, 328 mg, 1.6 mmol), 80%
NaH (in paran oil, 50 mg, 1.1 mmol) was added while
the reaction ¯ask was cooled down to 5ꢀC. After evo-
lution of H2, a solution of 21b (199 mg, 0.83 mmol) in
dry benzene (3 mL) was added, followed by re¯uxing
under argon for 4.5 h. The crude product was chroma-
tographed on silica gel column (hexane:EtOAc, 8:2) to
give 30b (150 mg, 63%).
(CDCl3) d 1.04 (s, 3H, H8), 2.29 (s, 3H, CH3CO), 2.49
(d, 1H, J=16.6, H4), 2.63 (d, 1H, J=16.6, H4), 6.03 (d,
1H, J=15.8, H10) 6.92 (dd, 1H, J1=15.8 and J2=9.0,
H9). 13C NMR (see Table 1). MS m/z (%): 236 (M+, 3),
218 (M+ H2O, 3), 43 (100).
4-[(1R,3aS,5R,7aR)-3a,5-Dihydroxy-7a-methylperhydro-
inden-1-yl]-3E-buten-2-one (28a) and 4-[(1R,3aS,5S,
7aR)-3a,5-dihydroxy-7a-methylperhydroinden-1-yl]-3E-
buten-2-one (28b). To an ice-cold solution ( 5ꢀC) of
27b (117 mg, 0.53 mmol) in dry MeOH, NaBH4 (7 mg,
0.18 mmol) was added. The mixture was stirred at 5ꢀC
under argon for 1 h and 15 min. Then, it was extracted
with EtOAc, washed with brine, dried and evaporated.
The crude reaction product was puri®ed by chromato-
graphy (hexane:EtOAc, 9:1) to obtain 28a (30 mg, 25%)
and 28b (35 mg, 29%).
30b. [a]d+10.2ꢀ (c 1.00, CHCl3). IR: 3460, 1620,
1175 cm 1. 1H NMR (CDCl3) d 0.81 (s, 3H, H8), 2.25 (s,
3H, CH3S), 2.67 (q, 1H, J=8.0, H1), 3.97 (br s, 4H,
OCH2), 5.31 (dd, 1H, J1=15.0 and J2=8.0, H9), 5.93
(d, 1H, J=15.0, H10). 13C NMR (see Table 1). MS m/z
(%): 284 (M+, 3), 266 (M+ H2O, 49), 169 (100).
(1R,3aS,7aR)-3a-Hydroxy-7a-methyl-1-[(E)-2-methyl-
thiovinyl]perhydroinden-5-one (31b). The reaction was
carried out under the conditions described above for
compound 27b, yielding 31b (99%).
28a. [a]d 4.1ꢀ (c 0.90, CHCl3). IR: 3400, 1670, 1620,
1
1170, 1060 cm 1. H NMR (CDCl3) d 0.83 (s, 3H, H8),
2.27 (s, 3H, CH3-CO), 2.87 (q, 1H, J=8.5, H1), 3.86 (m,
1H, H5), 6.01 (d, 1H, J=15.8, H10), 6.71 (dd, 1H,
J1=15.8 and J2=8.4, H9). 13C NMR (see Table 1).
1
31b. IR: 3410, 1710, 1150 cm 1. H NMR (CDCl3) d
0.96 (s, 3H, H8), 2.27 (s, 3H, CH3S), 2.41 (d, 1H,
J=14.8, H4), 2.53 (d, 1H, J=14.8, H4), 2.70 (q, 1H,
J=8.8, H1), 5.45 (dd, 1H, J1=14.8 and J2=8.8, H9),
6.02 (d, 1H, J=14.8, H10). 13C NMR (see Table 1). MS
m/z (%): 240 (M+, 32), 222 (M+ H2O, 12), 85 (100).
28b. [a]d+7.9ꢀ (c 0.80, CHCl3). IR: 3380, 1660, 1620,
1
1160, 1100 cm 1. H NMR (CDCl3) d 0.88 (s, 3H, H8),
2.27 (s, 3H, CH3-CO), 2.70 (q, 1H, J=8.4, H1), 4.16 (m,
1H, H5), 5.99 (d, 1H, J=15.8, H10), 6.75 (dd, 1H,
J1=15.8 and J2=8.4, H9). 13C NMR (see Table 1).
(1R,3aS,5S,7aR)-7a-Methyl-1-[(E)-2-methylthiovinylper-
hydroindene-3a,5-diol (32b). The reaction was carried
out under the conditions previously described for 28b,
obtaining 32b (75%).
(1R,3aS,5R,7aR)-3a-Hydroxy-7a-methyl-1-(3-oxo-1E-
butenyl)perhydroinden-5-yl acetate (29a). To a solution
of 28a (28 mg, 0.12 mmol) in CH2Cl2 (1 mL), pyridine
(0.30 mL) and acetic anhydride (0.30 mL) were added.
After stirring for 12 h, it was worked up as usually
yielding 29a (30 mg, 92%).
32b. Mp: 168ꢀC (AcOEt/diethyl ether). IR: 3320, 1610,
1
1170, 1060 cm 1. H NMR (CDCl3) d 0.77 (s, 3H, H8),
2.25 (s, 3H, CH3S), 2.78 (q, 1H, J=8.6, H1), 3.85 (tt,
1H, J1=10.4 and J2=5.8, H5), 5.28 (dd, 1H, J1=14.8
and J2=8.8, H9), 5.94 (d, 1H, J=14.8, H10). 13C NMR
29a. [a]d+3.40ꢀ (c 0.95, CHCl3). IR: 3420, 1720, 1670,
1
1625, 1170 cm 1. H NMR (CDCl3) d 0.85 (s, 3H, H8),

L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
2999
(see Table 1). MS m/z (%): 242 (M+, 38), 224
3600. H NMR (CDCl3) d 0.95 (s, 3H, H8), 3.70 (q, 1H,
J=8, H1), 6.65 (d, 1H, J=8, H9), 7.32 (1H,=N±OH).
13C NMR (see Table 1).MS m/z (%): 238 (M+, 21), 222
(M+ H2O, 2), 99 (100).
1
(M+ H2O, 18), 85 (100).
(1R,3aS,5S,7aR)-3a-Hydroxy-7a-methyl-1-[(E)-2-methyl-
thiovinyl]perhydroinden-5-yl acetate (33b). Compound 33b
was obtained in the same way as that of 29b, in 70% yield.
(1S,7aR)-7a-Methyl-5-oxo-2,3,5,6,7,7a-hexahydro-1H-
indene-1-carbaldehyde
bis(guanylhydrazone)
(38b).
1
33b. H NMR (CDCl3) d 0.80 (s, 3H, H8), 2.03 (s, 3H,
Aldehyde 21b (100 mg, 0.41 mmol) was dissolved in
EtOH (7 mL). The resultant solution was treated with
aminoguanidine hydrochloride (2 equiv, prepared by
adding HCl 2 N to aminoguanidine bicarbonate until
pH 5). The mixture was re¯uxed for 30 min. Then the
solvent was evaporated and the solid recrystallised to
obtain 38b (70 mg, 58%) as a white solid.
CH3COO), 2.25 (s, 3H, CH3S), 2.77 (q, 1H, J=8.8, H1),
4.94 (tt, 1H, J1=11.0 and J2=6.0, H5), 5.28 (dd, 1H,
J1=15.0 and J2=8.6, H9), 5.94 (d, 1H, J=15.0, H10).
13C NMR (see Table 1).
(1S,3aS,7aR)-3a-Hydroxy-7a-methyl-1-[(E)-2-nitrovinyl]-
perhydroinden-5-one ethylenic acetal (34a) and
(1R,3aS,7aR)-3a-hydroxy-7a-methyl-1-[(E)-2-nitrovinyl]-
perhydroinden-5-one ethylenic acetal (34b). A solution of
aldehyde 21b (134 mg, 0.47 mmol) and NH4AcO (48 mg,
0.6 mmol) in CH3NO2 (3 mL) was re¯uxed for 1 h. After
that period of time, it was extracted with CH2Cl2,
washed with brine and dried to obtain 180 mg of a
mixture of two isomers, which was resolved through a
column chromatography (CH2Cl2:EtOAc, 8:2) yielding
34b (60 mg, 37%) and 34a (40 mg, 26%).
38b. Mp: 248ꢀC (MeOH). [a]d +4.1ꢀ (c 0.75%, MeOH).
1
IR: 3200, 1670, 1625, 1115, 990, 865 cm 1. H NMR
(D2O) d 0.93 (s, 3H, H8), 5.94 (s, 1H, H4), 7.50 (d, 1H,
J=6.4, H9). 13C NMR (see Table 1). MS m/z (%): 291
(M++1, 43), 185 (100).
(3aS,7aR)-5,5-Ethylenedioxy-3a-hydroxyperhydroinden-
1-carbaldehyde guanylhydrazone (37). To a solution of
21b (30 mg, 0.13mmol) in EtOH (7 mL), aminoguanidine
hydrochloride (1 equiv) was added. The reaction mixture
was re¯uxed for 30 min. The solvent was evaporated
and the solid crystallised from MeOH to obtain 37
1
34a. H NMR (CDCl3) d 0.95 (s, 3H, H8), 2.87 (q, 1H,
J=8.3, H1), 6.99 (d, 1H, J=13.5, H10), 7.27 (dd, 1H,
J1=13.5 and J2=8.8, H9). 13C NMR (see Table 1).
(36 mg, 97%) as a mixture, in a 2:1 ratio, of the two iso-
1
mers (37a/37b). IR: 3350, 1672, 1626, 1121, 873 cm
.
1
34b. H NMR (CDCl3) d 0.90 (s, 3H, H8), 2.82 (q, 1H,
J=8.4, H1), 6.92 (d, 1H, J=13.6, H10), 7.23 (dd, 1H,
37a. 1H NMR (CD3OD) d 0.75 (s, 3H, H8), 2.61 (q, 1H,
J=7.2, H1) 3.76 (m, 4H, OCH2), 7.32 (d, 1H, J=7.2,
H9). 13C NMR (see Table 1).
J1=13.6 and J2=8.8, H9). 13C NMR (see Table 1).
(1R,7aR)-7a-Methyl-1-[(E)-2-nitrovinyl]-2,3,5,6,7,7a-hexa-
hydro-1H-indene-5-one guanylhydrazone (35b). To a
solution of the nitroderivative 34b (45 mg. 0.16 mmol) in
dry methanol (4 mL), aminoguanidine hydrochloride
(1 mmol, prepared by adding HCl 2 N to aminoguani-
dine bicarbonate until pH 5) was added. The reaction
mixture was heated to re¯ux for 30 min. The solvent was
removed under vacuum and the resultant solid was
recrystallised from MeOH/ether to obtain 35b (26 mg,
62%) as a white solid.
1
37b. H NMR (CD3OD) d 0.92 (s, 3H, H8), 2.37 (dd,
1H, J1=9.0 and J2=4.6, H1), 6.77 (d, 1H, J=8.6, H9).
13C NMR (see Table 1).
(3aS,7aR)-3a-Hydroxy-7a-methyl-5-oxoperhydroindene-
1-carbaldehyde bis(guanylhydrazone) (39). To a suspen-
sion of HgO (red) (255mg, 1.2 mmol) in THF:H2O, 85:15
.
(6.15 mL), BF3 Et2O (0.29 mL, 2.30 mmol) was added.
A solution of 22b (150 mg, 0.52 mmol) in THF
(27.3 mL) was added next. The mixture was stirred for
20 h at room temperature and then quenched by addi-
tion of CH2Cl2, ®ltrated and washed with Na2CO3 and
brine. After evaporation, the corresponding keto-alde-
hyde (80 mg, 76%) was obtained. This keto-aldehyde
(80 mg, 0.33 mmol) was dissolved in dry EtOH (7.3 mL),
and treated with aminoguanidine hydrochloride (2
equiv, prepared by adding HCl 6 N to a solution of
aminoguanidine bicarbonate until pH 5). The reaction
mixture was re¯uxed for 30 min under argon. The sol-
vent was evaporated and the residue crystallised from
MeOH:benzene to obtain a mixture of two isomers in a
35b. [a]d+34.6ꢀ (c 0.45). IR: 3310, 1672, 1626, 1520,
1
1350 cm 1. H NMR (CD3OD) d 0.91 (s, 3H, H8), 5.91
(s, 1H, H4), 7.11 (d, 1H, J=13.2, H10), 7.23 (dd, 1H,
J1=13.2 and J2=7.3, H9). 13C NMR (see Table 1).
FABHRMS m/z: calcd: 277.3261; found: 277.6628.
(1S,3aS,7aR)-3a-Hydroxy-1-hydroxyiminomethyl-7a-
methylperhydroinden-5-one ethylenic acetal (36). To a
solution of aldehyde 21b (110 mg, 0.46 mmol) in EtOH
(15 mL), pyridine (1.5 mL), HONH2.HCl (73.5 mg,
1.37 mmol) and NaOAc.3H2O (93.5 mg, 0.29 mmol)
were sequentially added. The mixture was re¯uxed for
2 h, then extracted with CH2Cl2, washed and dried.
After evaporating the solvent, a mixture of isomers Z/E
360 and 3600 (110 mg, 94%) was obtained.
1:1 ratio (39a:39b) (solid, 15 mg, 14%). IR: 3457, 1675,
1
1631, 1142, 1003, 880, 855 cm
.
39a. 1H NMR (CD3OD) d 0.90 (s, 3H, H8), 7.48 (d, 1H,
J=3.0, H9). 13C NMR (see Table 1).
360. H NMR (CDCl3) d 0.90 (s, 3H, H8), 2.82 (q, 1H,
1
J=8, H1), 7.36 (d, 1H, J=8, H9), 8.61 (br s, 1H, =N±
OH). 13C NMR (see Table 1).
39b. 1H NMR (CD3OD) d 0.88 (s, 3H, H8), 7.51 (d, 1H,
J=3.0, H9). 13C NMR (see Table 1).

3000
L. G. Sevillano et al. / Bioorg. Med. Chem. 7 (1999) 2991±3001
Methyl
[(1R,7aR)-7a-methyl-5-oxo-2,3,5,6,7,7a-hexa-
KCl, 5.4; CaCl2, 1.8; MgCl2, 1.05; NaHCO3, 24;
NaH2PO4, 0.42; glucose, 11. The solution was bubbled
with 95% O2±5% CO2 and maintained at 34ꢀC. Under
these conditions, right atria beat spontaneously, while
left atria were electrically driven at a basal rate of 2 Hz
through bipolar platinum electrodes, with rectangular
pulses (1 ms duration, twice threshold strength) deliv-
ered from a multipurpose programmable stimulator
(Cibertec CS.220, Cibertec SA, Madrid, Spain). Rate
and amplitude of contractions were measured iso-
metrically by a force-displacement transducer and
recorded on a Grass Moder 7B polygraph (Grass
Instrument Co., Quincy, MA, USA). Resting tension
was adjusted to 1 g and a 60 min equilibration period
was allowed to elapse before control measurements were
taken.
hydro-1H-inden-1-yl]acrylate (40b) and methyl [(1S,
7aR)-7a-methyl-5-oxo-2,3,5,6,7,7a-hexahydro-1H-indene-
1-yl]acrylate (40a). A solution of aldehyde 24b (44 mg,
0.25 mmol) and methoxycarbonylmethylentriphenyl-
phosphorane (100 mg, 0.30 mmol) in dry benzene (1 mL)
was stirred at re¯ux under argon for 1 h 30 min. The
crude product was chromatographed on a silica gel col-
umn (hexane:EtOAc, 6:1) to yield 40b (34 mg, 58%) and
40a (6 mg, 9%), both as colourless oils.
40a. [a]d 94ꢀ (c 0.15, CHCl3). IR: 1715, 1667, 1649,
1201, 829 cm 1. H NMR (CD3OD) d 1.12 (s, 3H, H8),
1
3.60±3.80 (m, 1H, H1), 3.71 (s, 3H, OMe), 5.79 (dd, 1H,
J1=2.2 and J2=1.8, H4), 5.93 (d, 1H, J=11.5, H10),
6.19 (dd, 1H, J1=11.5 and J2=10.4, H9). 13C NMR
(see Table 1). MS m/z (%) 234 (M+, 9), 202 (52), 174
(100).
The parameters of isometric contractions and cardiac
rate were determined as previously described.37 Follow-
ing a 60 min equilibration period, cumulative dose±
response curves to digoxin and compounds 35, 41 and
42 were constructed, increasing concentration at 20 min
intervals. Compound concentrations were used in the
40b. [a]d+81ꢀ (c 0.38, CHCl3). IR: 1727, 1667, 1649,
1201, 829 cm 1. H NMR (CD3OD) d 1.08 (s, 3H, H8),
1
3.76 (s, 3H, OMe), 5.80 (dd, 1H, J1=1.8 and J2=1.8,
H4), 5.90 (dd, 1H, J1=15.7 and J2=1.5, H10), 6.97 (dd,
1H, J1=15.7 and J2=7.7, H9). 13C NMR (see Table 1).
MS m/z (%) 234 (M+, 1), 202 (69), 174 (100).
6
range 10 7±10 M for digoxin (Boehringer digoxin1)
4
and 10 7±3Â10 M for 35, 41 and 42. Dose±response
curves with the vehicle employed for dissolving the
compounds (0.1±3% DMSO) were used as controls.
The values for di€erent parameters obtained in the
absence of drug were used as control and compared
with those obtained after each increment in drug con-
centration.
Methyl [(1R,7aR)-5-guanylhydrazono-7a-methyl-2,3,5,
a
6,7,7a-hexahydro-1H-indene-1-yl]acrylate (41). To
solution of 40b (37 mg, 0.16 mmol) in ethanol (3.4 mL),
aminoguanidine hydrochloride (19 mg, 0.17 mmol) and
HCl 2 N (74 mL) were added. The reaction mixture was
re¯uxed for 45 min, the solvent evaporated and the
residue crystallised from CH2Cl2:diethyl ether to obtain
41 (mixture 6:1 of E/Z isomers, 45 mg, 97%) as a white
solid.
The results obtained from a minimum of ®ve experi-
ments were expressed as means ‹ SEM Statistical
analysis of results were performed by unpaired Stu-
dent's t test. Probability levels of <0.05 were taken as
indicating statistical signi®cance.
41. [a]d+37.1ꢀ (c 0.35, MeOH). IR: 3352, 1719, 1671,
1624, 1277, 999 cm 1. H NMR (CDCl3) d 0.91 (s, 3H,
1
H8 (E)), 0.98 (s, 3H, H8 (Z)), 3.75 (s, 3H, OMe), 5.84 (s,
1H, H4), 5.92 (s, 1H, H10), 6.95 (dd, 1H, J1=15.0,
J2=6.9, H9). 13C NMR (see Table 1). FABHRMS m/z:
calcd: 290.3648; found: 290.5718.
Acknowledgements
Financial support came from the Spanish CICYT
(SAF95-1566) and Junta de Castilla y Leon (SA02/99).
C.P.M. and L.G.S. thank the Spanish M.E.C. for their
predoctoral fellowship positions.
[(1S,7aR)-1-Hydroxymethyl-7a-methyl-2,3,5,6,7,7a-hexa-
hydro-1H-indene-5-one]guanylhydrazone (42). The reac-
tion was carried out in the way previously described.
From 1-hydroxymethyl-5-ketone 19b (75 mg, 0.42mmol),
after crystallisation from MeOH:diethyl ether, 42 was
obtained (mixture 3:1 of E/Z isomers, 97 mg, 99%), as a
yellow solid.
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