Novel High Energy Intermediate Analogues with Triazasterol-Related Structures as Potential Inhibitors of the Ergosterol Biosynthesis II [1]. Optimization of the Synthesis of 1,6,7,11b-Tetrahydro-2H-pyrimido[4,3-a] isoquinolin-4-amines as Parent Compounds of Novel 8,13,15-Triazasteroids

Article abstract of DOI:10.1007/s00706-002-0559-7

Summary. Various routes for an effective synthesis of 1,6,7,11b-tetrahydro- 2H-pyrimido[4,3-a]isoquinolin-4-amine and its 9-methoxy derivative, which were designed as tricyclic triaza-analogues with stable positive charge to mimic carbocationic high energy intermediates (HEI) of the ergosterol biosynthesis, were investigated. Starting from β-phenylethylamines the corresponding 3-chloro-N-phenethylpropionamides were prepared and transformed into N-phenethyl-3-phthalimidopropionamides. These amides were cyclized via Bischler-Napieralski reaction to yield after hydrolytic deprotection 1-(aminoethyl)tetrahydroisoquinolines. The 1,6,7,11b-tetrahydro-2H-pyrimido[4,3- a]isoquinoline ring system was then built up by condensation of the bicyclic diamines with various carbonic acid derivatives (carbon disulfide, nitroguanidine, tetraethyl orthocarbonate). Along with the applied reaction sequences unexpected side reactions took place. The structures of all isolated compounds were proven and completely assigned on the basis of homo- and heteronuclear correlated 1D and 2D NMR experiments. The in vitro antifungal susceptibility tests with a standard panel of eight pathogenic fungi revealed only weak antimycotic effects of the pyrimidoisoquinolinamine salts, but strong inhibitory activity of the intermediate 1-(aminoethyl)-3,4-dihydroisoquinoline.

Full text of DOI:10.1007/s00706-002-0559-7

Monatshefte f€ur Chemie 134, 909–927 (2003)
DOI 10.1007/s00706-002-0559-7
Novel High Energy Intermediate Analogues
with Triazasterol-Related Structures
as Potential Inhibitors of the Ergosterol
Biosynthesis II [1]. Optimization
of the Synthesis of 1,6,7,11b-Tetrahydro-2H-
pyrimido[4,3-a] isoquinolin-4-amines
as Parent Compounds of Novel 8,13,15-
Triazasteroids
ꢀ
¨ ¨
Edith Goßnitzer and Asbjorn Punkenhofer
Institute of Pharmaceutical Chemistry and Pharmaceutical Technology,
Karl-Franzens-University Graz, A-8010 Graz, Austria
Received August 26, 2002; accepted September 2, 2002
Published online February 3, 2003 # Springer-Verlag 2003
Summary. Various routes for an effective synthesis of 1,6,7,11b-tetrahydro-2H-pyrimido[4,3-a]iso-
quinolin-4-amine and its 9-methoxy derivative, which were designed as tricyclic triaza-analogues with
stable positive charge to mimic carbocationic high energy intermediates (HEI) of the ergosterol
biosynthesis, were investigated. Starting from ꢀ-phenylethylamines the corresponding 3-chloro-N-
phenethylpropionamides were prepared and transformed into N-phenethyl-3-phthalimidopropion-
amides. These amides were cyclized via Bischler-Napieralski reaction to yield after hydrolytic
deprotection 1-(aminoethyl)tetrahydroisoquinolines. The 1,6,7,11b-tetrahydro-2H-pyrimido[4,3-a]iso-
quinoline ring system was then built up by condensation of the bicyclic diamines with various carbonic
acid derivatives (carbon disulfide, nitroguanidine, tetraethyl orthocarbonate). Along with the applied
reaction sequences unexpected side reactions took place. The structures of all isolated compounds were
proven and completely assigned on the basis of homo- and heteronuclear correlated 1D and 2D NMR
experiments. The in vitro antifungal susceptibility tests with a standard panel of eight pathogenic fungi
revealed only weak antimycotic effects of the pyrimidoisoquinolinamine salts, but strong inhibitory
activity of the intermediate 1-(aminoethyl)-3,4-dihydroisoquinoline.
Keywords. 1-(Aminoethyl)tetrahydroisoquinolines; 1,6,7,11b-Tetrahydro-2H-pyrimido[4,3-a]iso-
quinolin-4-amines; High energy intermediate analogues; Structure elucidation; Fungicides.
ꢀ
Corresponding author. E-mail: edith.goessnitzer@uni-graz.at

¨
E. Goßnitzer and A. Punkenhofer
910
Introduction
Previously we reported on the synthesis of potent new antifungal N-alkyl-N0-(phen-
ethyl- and cyclohexenylethyl)guanidines and N2- and N2,4-substituted imidazolin-
2-amines, which represent monocyclic analogues of 8,13,15-triazasterols [1]. They
were designed as inhibitors of the ergosterol biosynthesis similar to potent anti-
mycotics such as azoles, allylamines, and morpholines [2–5]. The inhibition of the
fungal ergosterol synthesis causes serious malfunctions of the cell membrane,
inhibition of the fungal growth, and cell death [5].
The design of agents of this type bases on the knowledge that certain enzymes involved in the
ergosterol biosynthesis create carbocationic high energy intermediates (HEI) and bind these inter-
mediates more tightly than the uncharged substrates [6]. Furtheron, it is known that compounds
with structures similar to HEI and stable positive charge in corresponding positions, so called high
energy intermediate analogues (HEIA), are able to act as potent HEIA-type inhibitors of fungal
enzymes [5–8]. Among others, carbocationic HEIs with the positive center in the steroid nucleus at
C-14 (HEI I, generated by ꢀ14-reductase) and C-8 (HEI II, generated by ꢀ8–ꢀ7-isomerase) appear in
the course of the enzymatic transformation of lanosterol via fecosterol and episterol into ergosterol
[5, 7] (Fig. 1). The naturally occurring HEIs I and II could be mimicked by HEIA of type 1, i.e. N4-
alkyl substitued pyrimido[4,3-a]isoquinolinamines, which represent tricyclic analogues of 8,13,15-
triazasterols bearing a positive charge in the guanidinium moiety around C-14 (steroid numbering,
Fig. 1).
In this contribution we report on the elaboration of effective synthetic routes
to the 1,6,7,11b-tetrahydro-2H-pyrimido[4,3-a]isoquinolin-4-amines 22a and
22b representing the parent compounds of HEIAs of type 1. Thus, the de-
sired amine salts 22a, b Á HX were obtained in eight steps starting from the phe-
nethylamines 2a and 2b in excellent overall yields. The results of the antifungal
evaluation of the amine salts 22a, b Á HX and of some intermediates are also
reported.
Fig. 1. Enzymatic transformation of lanosterol into ergosterol via HEIs and general formula of
HEIA of type 1

Potential Inhibitors of the Ergosterol Biosynthesis
911
Results and Discussion
The key intermediates for the synthesis of the pyrimidoisoquinolinamines 22a and
22b are the 1-(aminoethyl)tetrahydroisoquinolines 10a and 10b. As depicted in
Scheme 1, the synthesis of 10a and 10b started from commercially available ꢀ-
phenylethylamines 2a and 2b. However, we prepared 3-methoxyphenethylamine
2b also readily from 3-methoxybenzaldehyde (16b) and nitromethane by a
Knoevenagel-type condensation according to Ref. [8] and reduction of the gener-
ated 3-methoxy-ꢀ-nitrostyrene (17b) with lithium aluminium hydride as shown in
Scheme 3. Reaction of the amines 2a and 2b with 3-chloropropionyl chloride in an
emulsion reaction mixture of chloroform and aqueous sodium bicarbonate to com-
bine with the liberated HCl gave quantitatively the corresponding 3-chloro-N-phen-
ethylpropionamides 3a and 3b [9]. Subsequently, the ꢀ-chloroamides 3a and 3b
were reacted with potassium phthalimide to provide the 3-phthalimidopropion-
amides 4a and 4b (Scheme 1).
The electrophilic ring closure reactions of the N-phenethylpropionamides 4a
and 4b were performed by Bischler-Napieralski cyclization to yield phthal-
imidoethyldihydroisoquinolines 6a and 6b. The optimization [10] up to nearly
Scheme 1

¨
E. Goßnitzer and A. Punkenhofer
912
quantitative yield of the cyclodehydratization reaction succeeded in a series of
experiments at last with polyphosphoric acid without solvent at 145ꢁC. The appli-
cation of various other Lewis acids (phosphorus oxychloride, phosphorus pen-
tachloride, phosphorus pentoxide), solvents (benzene, toluene, tetraline), and
reaction temperatures (80ꢁC, 110ꢁC, 160ꢁC) gave minor yields. As expected, the
presence of the electron-donating methoxy group in 4b para to the site of ring
closure facilitated the formation of the 6-methoxydihydroisoquinoline 6b, which
could be prepared by smooth boiling of 4b with POCl3 in benzene in a yield of
97%. The stereochemically unfavoured ortho ring closure product 7b was gener-
ated only in an analytical amount and was separated chromatographically. Product
7b was readily identified by 1H NMR spectroscopy via the typical signal pattern of
the vic-trisubstituted benzene moiety of the isoquinoline ring. The aromatic protons
of 7b in ortho (H-7) and in para (H-5) position to the methoxy group appear as
doublets at 6.71 ppm and 6.75 ppm. The meta positioned H-6 appeared as a triplet
at 7.20 ppm.
When chloro-N-phenethylpropionamide 3a was subjected to Bischler-
Napieralski conditions (heating with POCl3 and P2O5 in boiling m-xylene [11])
not only the ring closure reaction, but additionally a Friedel-Crafts alkylation of
the solvent m-xylene took place. Accordingly, the reaction produced 1-[2-(2,4-
dimethylphenyl)ethyl]-3,4-dihydroisoquinoline hydrochloride (5a Á HCl, Scheme 1).
Hence, it was necessary to transform the ꢀ-chloropropionamides 3a and 3b into the
phthalimido compounds 4a and 4b prior to their Bischler-Napieralski cyclization.
The structure of the xylylethylisoquinoline 5a Á HCl was verified by NMR. The
linkage of the xylyl residue to the isoquinolinethyl moiety of 5a Á HCl was indi-
cated by the high-field shifted triplet of the CH2-20 protons (2.39 ppm) in com-
parison with the ꢀ-methylene protons of the employed ꢀ-chloropropionamide 3a
(3.76 ppm). Further evidence of this linkage in 5a Á HCl gave the long-range con-
nectivity between C-3 of the xylyl residue (131.3 ppm) and the CH2-20 protons of
the ethyl residue (2.39 ppm). The cyclization to the isoquinoline ring was proved
by the multiple bond correlation of the 10-methylene protons at 2.11 ppm to the
aromatic carbons C-8a and C-4a.
In attempts to effect the cleavage of the phthalyl protecting group of 6a and 6b in a gentle way,
several alternative methods were explored, partly with surprising results. Application of the conventional
hydrazinolysis [12] of 6a and 6b gave a variety of reaction products and proved to be unsuitable. Thus,
we tried the methylhydrazine (ten molar excess) mediated removal of the phthalyl residue of 6b in highly
diluted dichloromethane solution at ambient temperature according to the procedure described in Ref.
[13]. However, although the reaction time was varied between 2–24 hours no definite product except the
educts could be isolated. Treatment of 6b with only four mole equivalents excess of methylhydrazine in
more concentrated dichloromethane solution under mild reaction conditions produced a mixture of 32%
of the desired 1-(2-aminoethyl)isoquinoline 9bÁ 2HCl and 46% of 1-(2-ammonioethyl)-6-methoxy-2-
methyl-3,4-dihydroisoquinolinium dichloride (11b). Change of the solvent to ethanol and refluxing of 6b
with a 4-fold molar amount of methylhydrazine for 3 hours afforded exclusively the N2-methyl com-
pound 11b in a yield of 61% (Scheme 1). In every case N-methylphthalhydrazide 15 (Scheme 2) was
isolated as the second main product of the hydrazinolyses.
The observed unexpected transfer of a methyl group from methylhydrazine to the isoquinoline
nitrogen could proceed through the route suggested in Scheme 2. Accordingly, the reaction starts with
the usual ring opening of the phthalimide in 6b by the nucleophilic attack of methylhydrazine. The

Potential Inhibitors of the Ergosterol Biosynthesis
913
Scheme 2
isoquinoline moiety of the generated N,N0-disubstituted phthalamidehydrazide 12b could exhibit a
canonical form with a para-quinoid structure due to the electron-donating methoxy group with
increased electron density of the isoquinoline nitrogen N-2 (see little arrows in Scheme 2). Intramo-
lecular nucleophilic attack of N-2 on the methyl group of the 10-methylhydrazide moiety results in the
formation of (N2-methylisoquinolinioethyl) phthalamohydrazide 13b. Further hydrazinolysis of the
amide substructure of 13b generates the ion pair of N-methylisoquinolinium 11bþ and N-methyl-
phthaldihydrazide 14À (I). Tautomerization of 14À (I) into 14À (II) and ring closure under elimination
of hydrazine affords N-methylisoquinolinium N-methylphthalhydrazide 11bþ Á 15À . Working up with
hydrochloric acid yields a product mixture of dichloride 11b and hydrazide 15, which could be
separated.
As a quaternized imine the unexpectedly formed N-methylisoquinolinium
cation 11bþ bears a steady positive charge delocalized between C-8 and C-9
(sterol numbering, compare Fig. 1) and represents an interesting new type of
HEIA.
Finally, the phthalyl-protection group of 6a and 6b was successfully hydro-
lyzed in one step with boiling concentrated hydrochloric acid (Scheme 1).
The subsequent reduction of the generated 3,4-dihydroisoquinolines
9a, b Á 2HCl to rac-1-(2-aminoethyl)tetrahydroisoquinolines 10a, b Á 2HCl pro-
ceeded readily with sodium borohydride in excellent yields (Scheme 1). It was
important to carry out the reduction after the deprotection of the ꢀ-aminoethyl
residue. When phthalimidoethyldihydroisoquinoline 6a was treated with NaBH4
a reductive ring closure reaction [14] took place to furnish a new pentacyclic ring
system, i.e. isoindolo[10,20:2,1]pyrimido[4,3-a]isoquinoline 8a (Scheme 1). On the
separation of the generated diastereoisomers of 8a and their full stereochemical
characterization we will report lateron.
Alternatively, we tried to obtain tetrahydroisoquinoline derivatives 18 in a
single step by a Pictet-Spengler-type reaction [10]. For this purpose the amine
2a was condensed under various reaction conditions with cyanoacetaldehyde,
which was liberated from its diethylacetal under acidic conditions, to yield
1-cyanomethyl-1,2,3,4-tetrahydroisoquinoline salt 18a Á HCl (Scheme 3). However,
these experiments resulted in the production of an amount of tar and only poor
yields of product 18a Á HCl.

¨
E. Goßnitzer and A. Punkenhofer
914
Scheme 3
Synthesis of Tetrahydro-2H-pyrimido[4,3-a]isoquinolin-4-amines 22a and 22b
For the synthesis of the tricyclic amines 22a and 22b we investigated four alter-
native reaction pathways A-D (Scheme 4). Each route should be also applicable to
the synthesis of N 4-alkyl substituted 2H-pyrimido[4,3-a]isoquinolin-4-amines as
HEIAs of type 1 (Fig. 1).
The direct and shortest way [A] for the preparation of 22a, b Á HX would have been the cyclo-
condensation of the 1,5-diamine salts 10a, b Á 2HCl with cyanamide according to Ref. [15]. But none of
the respective experiments in various solvents (ethanol, butanol, DMF, THF) gave the desired products.
Routes [B]-[D] should lead via reactive tricyclic intermediates to amines 22a and 22b. The inter-
mediate of route [B], 4-ethoxytetrahydro-2H-pyrimido[4,3-a]isoquinoline (23a), was prepared in mod-
erate yield (31%) by condensation of the diamine 10a with tetraethyl orthocarbonate in refluxing
toluene [16]. However, this approach was abandoned when it was found that the successive displace-
ment of the ethoxy group of 23a with ammonia to the amino compound 22a failed.
Scheme 4

Potential Inhibitors of the Ergosterol Biosynthesis
915
Scheme 5
A convenient method for the preparation of N2-substituted five and six mem-
bered cyclic guanidines via condensation of diamines with nitroguanidine has been
described by McKay et al. [17, 18]. However, following this procedure, we
obtained from the reaction of diamine 10a and nitroguanidine in aqueous solution
not only the 4-nitriminopyrimidoisoquinoline 20a but also the 4-amino compound
22a (route [C], Scheme 4). Obviously, the cyclization reaction proceeded not uni-
formly under loss of two molecules of ammonia and retention of the nitramino
group but also under exchange of amino and nitramino group of the nitroguanidine.
Further degradation of 20a with water into the fused pyrimidinone 24a under
elimination of dinitrogen oxide as shown in Scheme 5 limited the use of this
reaction sequence with respect to our aim to generate 4-amino- and furtheron 4-
alkylamino pyrimidoisoquinolines 22 and 1.
The ultimately successful synthesis of 22a and 22b (route [D], Scheme 4)
consisted of the treatment of the ꢀ-aminoethyltetrahydroisoquinolines 10a and
10b with CS2 yielding the properly crystallizing cyclic thions 19a and 19b, and
subsequent methylation with methyl iodide generating the tricyclic isothiouronium
salts 21a, b Á HI. The nucleophilic displacement of the methylthio group of
21a, b Á HI with ammonia gave the salts of tetrahydro-2H-pyrimido[4,3-a]-isoqui-
nolin-4-amines 22a, b Á HX in good overall yields.
Spectroscopy and Stereochemistry
All structures and signal assignments of the reported substances were confirmed by
1D and 2D homo- and heteronuclear correlated NMR and NOE experiments as
well as by increment calculations [19–21] and proved to be as shown. The stereo-
chemistry of the 4-substituted tetrahydro-2H-pyrimido[4,3-a]isoquinoline ring sys-
tem common to amines 22a and 22b, and thions 19a and 19b as well as to the
methylthio, nitrimino and ethoxy compounds 21a, b Á HI, 20a, and 23a shall be
discussed in detail. All these tricyclic angularly fused compounds with an approxi-
mately planar arrangement of the guanidine (20a, 22a, 22b), thiourea (19a, 19b),
isothiourea (21a, 21b), and isourea (23a) moiety inclusive attached atoms show
very similar features in their NMR spectra. The characteristics are demonstrated by
the target compound 22a Á HI. It is noted that all compounds under study are race-
mates, whereas Fig. 2 shows only the structural formulae of the (11S)-enantiomers
with H-11b in the ꢀ-position.
A significant feature common to the five types of compounds is the chemical
shift value and the multiplicity of the methine proton H-11b. The H-11b signal of
22a Á HI appears at 4.77 ppm as a double doublet with J ¼ 10.8 and 4.0 Hz, in which

¨
E. Goßnitzer and A. Punkenhofer
916
Fig. 2. Stereoformulae of 20a and 22a Á HI (only one enantiomer shown; arrows indicate signifi-
cant NOEs)
the large coupling (10.8 Hz) to H-1ax reveals the trans-diaxial arrangement of the
coupling protons. The signals of the two ethylene ring moieties –C1H2–C2H2– of
the pyrimidine subunit and –C6H2–C7H2– of the isoquinoline part of 22a Á HI are
distinct and well resolved. Their multiplicities and magnitudes (2Jgem ¼ 3Jax,ax
ꢂ
12–13 Hz, Jax,eq ¼ 3Jeq,eq ꢂ 3–4 Hz) are in agreement with axial and equatorial
positions [21]. NOESY experiments showed mutual dipolar interactions between
H-11b, H-6ax, and H-2ax, which indicate their near spatial arrangement on the same
face of the molecule (Fig. 2). As can be judged from the Dreiding molecular model
all these results are consistent with a half-chair like conformation of the tetrahy-
dropyridine ring in which C-7, C-7a, C-11a, and C-11b are almost in one plane.
Due to the guanidinium moiety the anellated tetrahydropyrimidine ring adopts a
sofa conformation with C-1 being the out-of-plane atom (Fig. 2). Proton H-6eq
experiences a remarkable downfield shift to 4.19 ppm which is obviously the
result of the deshielding influence of the neighbouring approximately coplanar
guanidinuim moiety. The spatial proximity of H-6eq and the amino group at C-4
is also proved by the observed NOE between H-6eq and the NH2 protons at
7.51 ppm.
3
In case of nitrimino compound 20a the question of a possible nitramino-nitri-
mino tautomerism was elucidated by a NOESY experiment. The first hint sugges-
ting the existence of only one tautomer of 20a in CDCl3 solution at 298 K was the
appearence of a single resonance for the NH proton at 9.85 ppm with the intensity
1. The observed cross peak between the signals of the NH proton and the methy-
lene protons at C-2 in the NOESY contur plot revealed their spatial proximity and
proved the location of the NH proton at N-3. Hence, the CDCl3 solution contained
exclusively the nitrimino form of 20a with exocyclic C-4–N-4 double bond
(Fig. 2).
Antifungal Activity
The in vitro antifungal activities of the salts of 1-(aminoethyl)isoquinolines
9a, b Á 2HCl, 10a, b Á 2HCl, and of 2H-pyrimido[4,3-a]isoquinolinamines 22a, b Á HX
aresummerized inTable 1. The minimal inhibitory concentrations(MICs, mg Á cmÀ 3
)
with 80% and 100% growth inhibition were determined by the broth microdilution

Potential Inhibitors of the Ergosterol Biosynthesis
917
Table 1. In vitro antifungal activities of tested compounds; MICs in mg Á cmÀ 3 (80% and 100%
growth inhibition) against a standard panel of pathogenic fungi
Compound
Cand.
alb.
Cand.
alb.
Sach. Crypt. Asperg. Asperg. Trich.
Trich.
rubr.
cerev. neof.
fum.
fum.
ment.
9a Á 2HCl
9b Á 2HCl
10a Á 2HCl
10b Á 2HCl
22a Á HI
80%
1
2
8
8
4
4
0.5
0.5
8
8
16
16
4
8
2
4
100%
80%
64
64
64
64
64
64
64
64
64
64
64
64
64
64
64
100%
64
80% 128
128
128
128
128
32
32
128
128
128
128
128
128
128
128
100% 128
80% 128
128
128
128
128
32
32
128
128
128
128
128
128
128
128
100% 128
80%
64
64
64
64
64
64
64
64
64
64
64
64
64
64
64
64
100%
22b Á HCl
Itraconazole
80%
64
64
64
64
64
64
64
64
100% 128
128
128
128
128
128
128
128
80%
0.06
0.13
1
2
0.03
0.5
0.5
0.5
0.13
0.25
2
100% >4
>4
1
1
1
method [22] with use of eight fungal strains and itraconazole as reference test
compound. Most of the tested compounds (9b Á 2HCl, 10a, b Á 2HCl, 22a, b Á HX)
showed only weak inhibitory effects with MICs in the range of 32 to 128 mg Á cmÀ 3
.
In contrast, the intermediate aminoethyldihydroisoquinoline 9a Á 2HCl displayed sur-
prisingly strong effects against the used yeasts, dermatophytes, and moulds at MIC
.
levels between 0.5 and 16 mg Á cmÀ 3
Experimental
Melting points were determined on a Kofler melting point apparatus and are uncorrected. Thin layer
chromatograms (TLC) were run on TLC plastic sheets silica gel 60 F254 (E. Merck, Darmstadt).
The spots were detected by visual examination under UV light (254 and 366 nm) or visualized
with chlorine vapour. Column chromatography (CC) was performed using silica gel 60 (0.063–
0.200 mm, Merck). Infrared spectra were recorded with a 2000 FTIR spectrophotometer (s¼ strong,
m ¼ medium, w ¼ weak). NMR spectra were aquired on a Varian 400 MHz Unity Inova NMR spectro-
meter equipped with a Sun Sparc 5 computer system and operating at an observation frequency of
1
399.98 MHz for H and 100.59 MHz for 13C. 1D and 2D NMR experiments were performed using a
pulsed magnetic field gradient unit and a 5 mm inverse broadband probehead. The HH-COSY, gs-
HSQC, gs-HMBC, NOESY, and 1D NOE difference experiments were performed using the pulse
programs supplied by the manufacturer. The gs-HMBC experiments were optimized for 4, 8, and
10Hz nJCH giving delays of 125.0, 62.5, and 50.0ms. All NOEs were measured in samples degassed
by freeze-pump-thaw cycles, cooling in an ice bath. 15–25mg of the substances were dissolved in
0.5 cm3 of deuterated solvents and measured at 298K. All chemical shifts are reported with TMS as
internal standard. For a convenient reading correlating spin systems are reported coherently, assign-
ments marked with an asterisk are interchangeable. Elemental analyses were performed by J. Theiner,
Microanalytical Laboratory at the University of Vienna, Institute of Physical Chemistry; they were
found to agree favourably with the calculated values.

¨
E. Goßnitzer and A. Punkenhofer
918
2-(3-Methoxyphenyl)ethylamine hydrochloride (2b Á HCl)
Salt 2b Á HCl was prepared according to the method described in Ref. [8] from 8.90g of ꢀ-nitrostyrene
17b (50 mmol) and 6.82g of LiAlH4 (180 mmol) in 60cm3 of dry Et2O. The obtained crude amine 2b
was mixed with 6 M ethanolic HCl and the solvent was removed under reduced pressure. The resulting
solid was triturated with acetone to give 6.50 g (70%) of 2b Á HCl. Mp: 132ꢁC (Ref. [23] 133–135ꢁC);
TLC (toluene:isopropanol:diethylamine ¼ 6:3:1): Rf ¼ 0.38; IR (KBr): ꢁꢁ ¼ 3376ðsÞ, 2979(s), 2891(s),
1603(s), 1480(s), 1469(s), 1319(m), 1272(s), 858(s) cmÀ 1
;
1H NMR (DMSO-d6): ꢂ ¼ 2.87 (t,
J ¼ 7.8 Hz, 2H, CH2-2), 2.99 (m, 2H, CH2-1), 3.73 (s, 3H, OCH3), 6.82 (m, 3H, H-2, H-4, H-6,
C6H4), 7.22 (t, J ¼ 7.6 Hz, 1H, H-5, C6H4), 8.21 (bs, 3H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 32.9
(C-2), 39.4 (C-1), 55.0 (OCH3), 112.2 (C-4, C6H4), 114.2 (C-2, C6H4), 120.8 (C-6, C6H4), 129.6 (C-5,
C6H4), 139.0 (C-1, C6H4), 159.4 (C-3, C6H4) ppm.
3-Chloro-N-phenethylpropionamide (3a)
To a vigorously stirred mixture of 12.1g of 2a (0.10 mol) in 300 cm3 of CHCl3 and 400 cm3 of aqueous
5% NaHCO3 solution of 14.0g of 3-chloropropionyl chloride (0.11 mol) were added dropwise within
1 h under cooling with an ice bath. After additional stirring for 1 h at ambient temperature the aqueous
layer was separated and extracted with 2ꢃ50cm3 of CHCl3. The combined organic layers were dried
(Na2SO4) and concentrated in vacuo to give 21.2g of already pure, crystalline 3a in quantitative yield.
Mp: 55ꢁC (Ref. [9] 52ꢁC); TLC (MeOH:MeCN ¼ 1:1): Rf ¼ 0.61; IR (KBr): ꢁꢁ ¼ 3302ðsÞ, 2972(m),
1
2938(m), 1641(s), 1555(s), 1421(m), 1290(m), 1152(m), 927(m), 742(m), 699(s) cmÀ 1; H NMR
(DMSO-d6): ꢂ ¼ 2.53 (t, J ¼ 6.8 Hz, 2H, CH2-2), 2.70 (t, J ¼ 7.2 Hz, 2H, CH2-20, ethyl), 3.28 (q,
J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 3.76 (t, J ¼ 6.8 Hz, 2H, CH2-3), 7.19 (m, 3H, o-H, p-H, C6H5), 7.27
(m, 2H, m-H, C6H5), 8.09 (bs, 1H, NH) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 35.6 (C-20, ethyl), 39.6 (C-2),
ꢀ
ꢀ
40.1 (C-3), 40.7 (C-10, ethyl), 126.6 (p-C, C6H5), 128.6 (o-C , C6H5), 128.7 (m-C , C6H5), 138.7 (C-1,
C6H5), 169.3 (C-1) ppm.
3-Chloro-N-[2-(3-methoxyphenyl)ethyl]propionamide (3b)
Following the procedure described for 3a, reaction of 15.2g of 2b (0.10 mol) and 14.0g of 3-chloro-
propionyl chloride (0.11 mol) afforded 24.1g of pure yellowish oily 3b in quantitative yield, which
solidified after drying in vacuo. Mp: 46ꢁC (Ref. [9] 48ꢁC); TLC (ethyl acetate:MeOH ¼ 5:1):
Rf ¼ 0.57; IR (KBr): ꢁꢁ ¼ 3305ðsÞ, 2935(m), 1636(s), 1584(s), 1549(s), 1491(m), 1437(m), 1260(s),
1156(s), 1061(m), 782(m) cmÀ 1
;
1H NMR (CDCl3): ꢂ ¼ 2.56 (t, J ¼ 6.8 Hz, 2H, CH2-2), 2.78
(t, J ¼ 7.2 Hz, 2H, CH2-20, ethyl), 3.54 (q, J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 3.73 (t, partly overlapped,
J ¼ 6.8 Hz, 2H, CH2-3), 3.75 (s, 3H, OCH3), 6.03 (bs, 1H, NH), 6.72 (d, J ¼ 1.6 Hz, 1H, H-2, C6H4),
6.76 (m, 2H, H-4, H-6, C6H4), 7.21 (t, J ¼ 7.6 Hz, 1H, H-5, C6H4) ppm; 13C NMR (CDCl3): ꢂ ¼ 35.5
(C-20, ethyl), 39.3 (C-2), 40.1 (C-3), 40.6 (C-10, ethyl), 55.1 (OCH3), 111.8 (C-2, C6H4), 114.3 (C-4,
C6H4), 120.9 (C-6, C6H4), 129.1 (C-5, C6H4), 140.2 (C-1, C6H4), 159.7 (C-3, C6H4), 169.5 (C-1) ppm.
N-Phenethyl-3-phthalimidopropionamide (4a, C19H18N2O3)
ꢀ-Chloropropionamide 3a (4.23 g, 20.0mmol) and 4.63 g of potassium phthalimide (25.0 mmol) were
dissolved in 25cm3 of dry DMF and heated at 140ꢁC under stirring for 6 h. After cooling, the reaction
mixture was diluted with 200 cm3 of H2O and 50cm3 of 2 N NaOH solution, and extracted with
3 ꢃ 30cm3 of CHCl3. The combined organic layers were dried with Na2SO4 and concentrated in
vacuo to give crystalline 4a. Treatment of raw 4a with Et2O yielded 5.72g (89%) of colourless needles.
Mp: 180ꢁC; TLC (ethyl acetate:toluene ¼ 1:1): Rf ¼ 0.20; IR (KBr): ꢁꢁ ¼ 3309ðsÞ, 2931(w), 1770(m),
1709(s), 1635(s), 1547(s), 1444(m), 1400(s), 1235(m), 997(m), 722(s) cmÀ 1 1H NMR (CDCl3):
;
ꢂ ¼ 2.55 (t, J ¼ 7.2 Hz, 2H, CH2-2), 2.77 (t, J ¼ 7.2 Hz, 2H, CH2-20, ethyl), 3.49 (q, J ¼ 7.2Hz, 2H,

Potential Inhibitors of the Ergosterol Biosynthesis
919
CH2-10, ethyl), 3.96 (t, J ¼ 7.2 Hz, 2H, CH2-3), 5.62 (bs, 1H, NH), 7.13 (d, J ¼ 7.2 Hz, 2H, o-H, C6H5),
7.16 (t, J ¼ 7.2Hz, 1H, p-H, C6H5), 7.25 (t, 2H, J ¼ 7.2 Hz, m-H, C6H5), 7.68 (m, 2H, H-4=5,
phthalimide), 7.80 (m, 2H, H-3=6, phthalimide) ppm; 13C NMR (CDCl3): ꢂ ¼ 34.3 (C-3), 34.8 (C-
2), 35.5 (C-20, ethyl), 40.6 (C-10, ethyl), 123.3 (C-3=6, phthalimide), 126.5 (p-C, C6H5), 128.6 (m-C,
C6H5), 128.7 (o-C, C6H5), 132.0 (C-1=2, phthalimide), 134.0 (C-4=5, phthalimide), 138.7 (C-1, C6H5),
168.1 (C¼O, phthalimide), 169.5 (C-1) ppm.
N-[2-(3-Methoxyphenyl)ethyl]-3-phthalimidopropionamide (4b, C20H20N2O4)
Following the procedure described for 4a, reaction of 3.93g of amide 3b (16.3mmol) and 3.78g of
potassium phthalimide (20.4 mmol) afforded 4.62g (80%) of colourless crystalline 4b. Mp: 150ꢁC
(Et2O); TLC (ethyl acetate:toluene ¼ 1:1): Rf ¼ 0.31; IR (KBr): ꢁꢁ ¼ 3325ðmÞ, 2947(w), 1771(m),
1
1713(s), 1637(s), 1548(m), 1398(m), 1259(m), 999(m), 721(m) cmÀ 1; H NMR (CDCl3): ꢂ ¼ 2.55
(t, J ¼ 7.2 Hz, 2H, CH2-2), 2.74 (t, J ¼ 7.2 Hz, 2H, CH2-20, ethyl), 3.47 (q, J ¼ 7.2 Hz, 2H, CH2-10,
ethyl), 3.76 (s, 3H, OCH3), 3.96 (t, J ¼ 7.2Hz, 2H, CH2-3), 5.70 (bs, 1H, NH), 6.71–6.80 (3H, H-2,
H-4, H-6, C6H4), 7.15 (t, J ¼ 7.6 Hz, 1H, H-5, C6H4), 7.69 (m, 2H, H-4=5, phthalimide), 7.81 (m, 2H,
H-3=6, phthalimide) ppm; 13C NMR (CDCl3): ꢂ ¼ 34.3 (C-3), 34.9 (C-2), 35.5 (C-20, ethyl), 40.5 (C-
10, ethyl), 55.1 (OCH3), 111.9 (C-2, C6H4), 114.3 (C-4, C6H4), 120.9 (C-6, C6H4), 123.3 (C-3=6,
phthalimide), 129.6 (C-5, C6H4), 131.9 (C-1=2, phthalimide), 133.9 (C-4=5, phthalimide), 140.3 (C-1,
C6H4), 159.8 (C-3, C6H4), 168.1 (C¼O, phthalimide), 169.5 (C-1) ppm.
1-[2-(2,4-Dimethylphenyl)ethyl)]-3,4-dihydroisoquinoline hydrochloride (5a Á HCl, C19H22ClN)
According to the general procedure of Ref. [11] the solution of 5.00g of amide 3a (24.0 mmol) in
75cm3 of dry 1,3-xylene was mixed with 10.0g of POCl3 (65.0mmol) and 10.0g of P4O10
(35.0mmol) under stirring and it was refluxed for 1 h. After cooling, the reaction mixture was poured
into ice=H2O, the separated aqueous phase made alkaline with 5 N NaOH solution and it was extracted
with 3 ꢃ 50 cm3 of toluene. The combined organic layers were dried with Na2SO4 and the solvent was
removed in vacuo. The obtained resin was treated with 10cm3 of 6 M ethanolic HCl and evaporated to
dryness. The residue was purified by successive column chromatographies on silica gel (toluene:
MeOH¼ 2:1, CHCl3:ethyl acetate ¼ 5:1) affording 2.81 g (39%) of 5aÁ HCl as honey-yellow resin.
1
TLC (CHCl3:ethyl acetate ¼ 5:1): Rf ¼ 0.69; H NMR (CDCl3): ꢂ ¼ 2.11 (t, J ¼ 7.2 Hz, 2H, CH2-10,
ethyl), 2.25 (s, 3H, CH3), 2.29 (s, 3H, CH3), 2.39 (t, J ¼ 7.2Hz, 2H, CH2-20, ethyl), 2.87 (t, J ¼ 7.6 Hz,
2H, CH2-4), 4.06 (t, J ¼ 7.6 Hz, 2H, CH2-3), 6.96 (s, 1H, H-3, xylyl), 7.01 (m, 2H, H-5, H-6, xylyl),
7.24–7.30 (m, 4H, H-5, H-6, H-7, H-8, isoquinoline), 12.80 (bs, 1H, NH-2) ppm; 13C NMR (CDCl3):
ꢀ
ꢂ ¼ 19.5 (CH3), 20.9 (CH3), 23.9 (C-4), 31.6 (C-20, ethyl), 35.1 (C-10, ethyl), 44.1 (C-3), 126.4 (C-7 ),
ꢀ
(C-8a), 136.4 (C-4, xylyl), 137.0 (C-2, xylyl), 138.4 (C-1, xylyl), 139.0 (C-4a), 169.8 (C-1) ppm.
126.6 (C-5, xylyl), 127.4 (C-6 ), 128.2 (C-6, xylyl), 129.0 (C-5), 129.8 (C-8), 131.3 (C-3, xylyl), 132.9
3,4-Dihydro-1-(2-phthalimidoethyl)isoquinoline (6a, C19H16N2O2)
To 36.0g of polyphosphoric acid, mechanically stirred and heated to 140ꢁC, was added 4.90 g of amide
4a (15.2mmol) in portions within 15 minutes. Thereafter, the brownish and viscous reaction mixture
was kept at 145ꢁC for 3.5 h. After cooling, the reaction mixture was cautiously diluted with 140cm3 of
H2O and adjusted to pH 9 with 5 N NaOH solution, and extracted with 3 ꢃ 30cm3 of CHCl3. The
combined organic layers were dried with Na2SO4 and the solvent was removed under reduced pressure.
Recrystallization from MeOH gave 4.12g (89%) of slight yellowish crystals of 6a. Mp: 176ꢁC; TLC
(CHCl3:ethyl acetate ¼ 1:1): Rf ¼ 0.18; IR (KBr): ꢁꢁ ¼ 3051ðwÞ, 2937(m), 2872(w), 1768(s), 1711(s),
1
1631(s), 1574(m), 1402(s), 1369(s), 1233(m), 1105(m), 999(m), 719(s) cmÀ 1; H NMR (CDCl3):

¨
E. Goßnitzer and A. Punkenhofer
920
ꢂ ¼ 2.68 (t, J ¼ 7.6 Hz, 2H, CH2-4), 3.09 (t, J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 3.65 (t, J ¼ 7.6 Hz, 2H,
CH2-3), 4.08 (t, J ¼ 7.2 Hz, 2H, CH2-20, ethyl), 7.17 (d, J ¼ 7.6 Hz, 1H, H-5), 7.24 (td, J ¼ 7.6, 1.6 Hz,
1H, H-7), 7.30 (td, J ¼ 7.6, 1.6 Hz, 1H, H-6), 7.48 (d, J ¼ 7.6 Hz, 1H, H-8), 7.69 (m, 2H, H-4=5,
13
phthalimide), 7.82 (m, 2H, H-3=6, phthalimide) ppm; C NMR (CDCl3): ꢂ ¼ 25.9 (C-4), 33.9 (C-10,
ethyl), 35.9 (C-20, ethyl), 46.9 (C-3), 123.1 (C-3=6, phthalimide), 124.6 (C-8a), 126.9 (C-6), 127.6 (C-
7), 128.3 (C-5), 130.6 (C-8), 132.2 (C-4=5, phthalimide), 133.8 (C-1=2, phthalimide), 137.7 (C-4a),
164.3 (C-1), 168.2 (C¼O, phthalimide) ppm.
3,4-Dihydro-6-methoxy-1-(2-phthalimidoethyl)isoquinoline (6b, C20H18N2O3)
and the 8-Methoxy Isomer 7b (C20H18N2O3)
A mixture of 2.50 g of 4b (7.10 mmol) and 7.50cm3 of POCl3 in 40cm3 of dry benzene were refluxed
for 3 h. The yellowish reaction mixture was concentrated in vacuo. The obtained sludge was diluted
with 80cm3 of H2O, made alkaline with 2 N NaOH solution and extracted with 3ꢃ 30cm3 of CHCl3.
The combined organic layers were dried with Na2SO4 and the solvent was removed in vacuo. Recrys-
tallization of the residue with 2-propanol yielded 2.23g (94%) of salmon pink coloured crystals of 6b.
Mp: 128ꢁC; TLC (ethyl acetate:MeOH ¼ 5:1): Rf ¼ 0.40; IR (KBr): ꢁꢁ ¼ 2933ðmÞ, 2842(m), 1765(m),
1708(s), 1608(s), 1566(s), 1399(s), 1360(s), 1259(s), 1147(m), 733(m), 717(m)cmÀ 1 1H NMR
;
(CDCl3): ꢂ ¼ 2.62 (t, J ¼ 7.2 Hz, 2H, CH2-4), 3.01 (t, J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 3.58 (t,
J ¼ 7.2 Hz, 2H, CH2-3), 3.76 (s, 3H, OCH3), 4.02 (t, J ¼ 7.2 Hz, 2H, CH2-20, ethyl), 6.65 (d, J ¼ 2.4 Hz,
1H, H-5), 6.70 (dd, J ¼ 8.4, 2.4Hz, 1H, H-7), 7.39 (d, J ¼ 8.4 Hz, 1H, H-8), 7.65 (m, 2H, H-4=5,
13
phthalimide), 7.78 (m, 2H, H-3=6, phthalimide) ppm; C NMR (CDCl3): ꢂ ¼ 26.4 (C-4), 33.9 (C-10,
ethyl), 35.9 (C-20, ethyl), 46.7 (C-3), 55.2 (OCH3), 111.8 (C-7), 112.9 (C-5), 122.3 (C-8a), 123.0 (C-3=6,
phthalimide), 126.5 (C-8), 132.2 (C-1=2, phthalimide), 133.7 (C-4=5, phthalimide), 139.9 (C-4a), 161.1
(C-6), 163.9 (C-1), 168.1 (C¼O, phthalimide) ppm.
The 8-methoxy isomer 7b (40 mg) was isolated from crude 6b via column chromatography on
silica gel (CH2Cl2:MeOH ¼ 10:1). TLC (ethyl acetate:MeOH¼ 5:1): Rf ¼ 0.41 (flourescent at UV254);
1H NMR (CDCl3): ꢂ ¼ 2.53 (t, J ¼ 7.2 Hz, 2H, CH2-4), 3.21 (t, J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 3.46 (t,
J ¼ 7.2 Hz, 2H, CH2-3), 3.82 (s, 3H, OCH3), 3.99 (t, J ¼ 7.2 Hz, 2H, CH2-20, ethyl), 6.71 (d, J ¼ 8.2 Hz,
1H, H-7), 6.75 (d, J ¼ 8.2 Hz, 1H, H-5), 7.20 (t, J ¼ 8.2 Hz, 1H, H-6), 7.65 (m, 2H, H-4=5, phthal-
imide), 7.76 (m, 2H, H-3=6, phthalimide) ppm.
( ꢄ )-5,6,14,15-Tetrahydro-4bH-isoindolo[10,20:2,1]pyrimido[4,3-a]isoquinolin-8(12bH)-one
(8a, C19H18N2O)
An ice-cooled solution of 1.83g of 6a (6.00 mmol) in 40cm3 of CHCl3 and 40cm3 of MeOH was
treated with 1.51 g of NaBH4 (40 mmol) and stirred for 1 h at room temperature. The mixture was
poured onto 500 cm3 of ice=H2O and extracted with 3 ꢃ 40cm3 of CHCl3. The organic layer was dried
with Na2SO4 and evaporated in vacuo. Colourless crystals of pure 8a were obtained quantitatively
(1.75 g). Mp: 130ꢁC; TLC (ethyl acetate:MeOH ¼ 5:1): Rf ¼ 0.21; IR (KBr): ꢁꢁ ¼ 3061ðwÞ, 2924(m),
2701(m), 1686(s), 1493(m), 1467(m), 1408(s), 1284(m), 1054(s), 746(s) cmÀ 1
.
1-(2-Aminoethyl)-3,4-dihydroisoquinoline dihydrochloride (9a Á 2HCl, C11H16Cl2N2)
Phthalimidoethylisoquinoline 6a (4.06 g, 13.3 mmol) and 42cm3 of conc. HCl were refluxed for 6 h.
On cooling, phthalic acid precipitated and was filtered off. The aqueous filtrate was diluted with 15cm3
of H2O and washed once with 30cm3 of CHCl3 to remove residual educt. The aqueous layer was
adjusted to pH 12 with 5 N NaOH solution, extracted with 3 ꢃ 15cm3 of CHCl3, dried with Na2SO4,
and the solvent was removed in vacuo. To the residue 3 cm3 of 6 M ethanolic HCl were added, the
solvent was evaporated, and the obtained solid triturated with acetone to give 3.04 g (92%) of slightly

Potential Inhibitors of the Ergosterol Biosynthesis
921
beige crystals of 9aÁ 2HCl. Mp: 189ꢁC (decomp.); TLC (toluene:MeOH¼ 1:1): Rf ¼ 0.38; IR (KBr):
ꢁꢁ ¼ 3424ðmÞ, 2902(s), 2828(s), 2662(s), 1664(s), 1601(m), 1568(m), 1316(m), 1163(m), 916(m),
746(m) cmÀ 1; 1H NMR (DMSO-d6): ꢂ ¼ 3.11 (t, J ¼ 7.6 Hz, 2H, CH2-4), 3.22 (m, 2H, CH2-20, ethyl),
3.57 (t, J ¼ 7.6Hz, 2H, CH2-10, ethyl), 3.82 (t, J ¼ 7.6 Hz, 2H, CH2-3), 7.50 (d, J ¼ 7.6 Hz, 1H, H-5),
7.54 (t, J ¼ 7.6Hz, 1H, H-7), 7.77 (t, J ¼ 7.6 Hz, 1H, H-6), 8.18 (d, J ¼ 7.6Hz, 1H, H-8), 8.54 (s, 3H,
NH-20), 14.11 (bs, 1H, NH-2) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 24.1 (C-4), 29.9 (C-10, ethyl), 36.6 (C-
20, ethyl), 40.9 (C-3), 125.1 (C-8a), 127.9 (C-7), 128.6 (C-5), 129.9 (C-8), 136.5 (C-6), 138.3 (C-4a),
174.3 (C-1) ppm.
1-(2-Aminoethyl)-3,4-dihydro-6-methoxyisoquinoline dihydrochloride
(9b Á 2HCl, C12H18Cl2N2O)
Following the procedure given for 9a, refluxing of 2.50g of 6-methoxyisoquinoline 6b (7.42 mmol)
in 50cm3 of conc. HCl for 5 h afforded 3.06g (80%) of 9bÁ 2HCl. Mp: 199ꢁC; TLC
(toluene:MeOH ¼ 1:1): Rf ¼ 0.24; IR (KBr): ꢁꢁ ¼ 3424ðwÞ, 2866(s), 2756(m), 1646(m), 1602(s),
1
1561(m), 1326(m), 1265(s), 1147(m), 907(w) cmÀ 1; H NMR (DMSO-d6): ꢂ ¼ 3.09 (t, J ¼ 7.6 Hz,
2H, CH2-4), 3.19 (m, 2H, CH2-20, ethyl), 3.53 (t, J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 3.76 (t, J ¼ 7.6 Hz,
2H, CH2-3), 3.91 (s, 3H, OCH3), 7.05 (dd, J ¼ 8.8, 2.8 Hz, 1H, H-7), 7.08 (s, 1H, H-5), 8.20
(d, J ¼ 8.8 Hz, 1H, H-8), 8.63 (bs, 3H, NH-20), 13.62 (bs, 1H, NH-2) ppm; 13C NMR (DMSO-d6):
ꢂ ¼ 24.7 (C-4), 29.7 (C-10, ethyl), 36.9 (C-20, ethyl), 40.5 (C-3), 55.2 (OCH3), 113.6 (C-7), 114.1 (C-5),
117.8 (C-8a), 133.1 (C-8), 141.6 (C-4a), 165.8 (C-6), 172.9 (C-1) ppm.
1-(2-Ammonioethyl)-3,4-dihydro-6-methoxy-2-methylisoquinolinium dichloride
(11b, C13H20Cl2N2O) and 1-(2-Aminoethyl)-3,4-dihydro-6-methoxyisoquinoline
dihydrochloride (9b Á 2HCl, C12H18Cl2N2O)
The hydrazinolysis was carried out in a modification of the procedure described in Ref. [13].
Method A: A solution of 1.00 g of phthalimidoisoquinoline 6b (3.00 mmol) and 0.55g of methyl-
hydrazine (12.0 mmol) in 60 cm3 of CH2Cl2 was stirred at 30ꢁC for 24h. Upon adding of 40cm3 of
H2O and 20 cm3 of 2 N HCl to the reaction mixture N-methylphthalhydrazide 15 precipitated and
was filtered off. The aqueous layer was separated from the filtrate, made alkaline with 2 N
NaOH solution and extracted with 3ꢃ 10 cm3 of CH2Cl2. The organic layer was mixed with 5 cm3
of 6 M ethanolic HCl and evaporated under vacuum. The obtained residue was separated by chroma-
tography on silical gel (MeOH:CH2Cl2 ¼ 10:1, 1:1) to yield 0.27g (32%) of 9bÁ 2HCl and 0.40g
(46%) of 11b.
Method B: A solution of 3.0 g of 6b (9.0mmol) and 1.65g of methylhydrazine (36.0 mmol) in
50cm3 of EtOH was refluxed for 3 h. The reaction mixture was concentrated under reduced pressure,
the solid residue was treated with 30 cm3 of H2O and 5 cm3 of 2 N HCl, and the precipitated N-
methylphthalhydrazide 15 was filtered off. The aqueous filtrate was made alkaline with 5 N NaOH
solution to pH >10 and extracted with 3 ꢃ 20cm3 of CH2Cl2. The organic layer was dried with
Na2SO4, filtered, mixed with 5 cm3 of 6 M ethanolic HCl, and evaporated. The obtained yellow residue
was recrystallized from acetone to give 1.60g (61%) of 11b. Mp: 214ꢁC; TLC (CH2Cl2:MeOH ¼
10:1): Rf ¼ 0.10; IR (KBr): ꢁꢁ ¼ 3406ðwÞ, 2970(s), 2624(m), 2519(m), 1608(s), 1599(s), 1560(m),
1
1469(m), 1353(s), 1251(s), 1033(m), 827(m)cmÀ 1; H NMR (DMSO-d6): ꢂ ¼ 2.98 (m, 2H, CH2-20,
ethyl), 3.16 (s, 3H, CH3N-2), 3.26 (t, J ¼ 7.2Hz, 2H, CH2-4), 3.57 (t, J ¼ 6.8 Hz, 2H, CH2-10, ethyl),
3.61 (t, J ¼ 7.2Hz, 2H, CH2-3), 6.98 (dd, J ¼ 8.8, 2.4 Hz, 1H, H-7), 7.04 (d, J ¼ 2.4 Hz, 1H, H-5), 7.64
13
(d, J ¼ 8.8, 2.4 Hz, 1H, H-8), 8.31 (bs, 3H, NH); C NMR (DMSO-d6): ꢂ ¼ 32.5 (C-4), 37.8 (C-20,
ethyl), 39.2 (C-10, ethyl), 43.1 (CH3N-2), 51.6 (C-3), 55.5 (OCH3), 112.5 (C-7), 117.6 (C-5), 120.1 (C-
8a), 133.4 (C-8), 140.1 (C-4a), 161.5 (C-6), 172.1 (C-1) ppm.

¨
E. Goßnitzer and A. Punkenhofer
922
( ꢄ )-1-(2-Aminoethyl)-1,2,3,4-tetrahydroisoquinoline dihydrochloride (10a Á 2HCl)
To an ice-cooled solution of 4.60 g of amine salt 9a Á 2HCl (18.6 mmol) in 50 cm3 of MeOH 1.85g of
NaBH4 (48.9mmol) were added in portions within 1.5 h. The brownish reaction mixture was stirred for
1 h at room temperature and changed its colour to yellowish. After addition of 5 cm3 of conc. HCl, the
precipitated solid was filtered off and washed with little MeOH. The combined MeOH filtrates were
evaporated to dryness and the obtained resin was dissolved in 50cm3 of H2O, made alkaline with 5 N
NaOH solution and extracted with 3 ꢃ 30cm3 of CHCl3. To the combined organic layers 6 M ethanolic
HCl was added to pH 3 and the solution was evaporated to dryness in vacuo. The obtained solid was
triturated with acetone to give in quantitative yield (4.62 g) slightly beige crystals of 10a Á 2HCl. Mp:
224ꢁC (Ref. [24] 245–246ꢁC); TLC (toluene:MeOH¼ 1:2): Rf ¼ 0.28; IR (KBr): ꢁꢁ ¼ 3426ðmÞ,
1
2935(s), 2728(s), 1592(m), 1493(m), 1454(m), 1140(w), 774(m), 763(m)cmÀ 1; H NMR (DMSO-
d6): ꢂ ¼ 2.34 (q, J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 2.98 and 3.10 (dt, J ¼ 16.0, 5.6Hz, 1H, Ha-4, and m,
1H, Hb-4), 3.22 (m, 2H, CH2-20, ethyl), 3.41 (m, 2H, CH2-3), 4.72 (m, 1H, H-1), 7.21 (d, J ¼ 7.8 Hz,
1H, H-5), 7.27 (m, 2H, H-6, H-7), 7.34 (d, J ¼ 8.0 Hz, 1H, H-8), 8.27 (bs, 3H, NH-20), 9.69 (bs, 1H,
NHa-2), 10.02 (bs, 1H, NHb-2) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 24.7 (C-4), 31.0 (C-10, ethyl), 35.3 (C-
ꢀ
ꢀ
20, ethyl), 38.6 (C-3), 51.4 (C-1), 126.4 (C-8), 126.7 (C-7 ), 127.5 (C-6 ), 128.9 (C-5), 132.2 (C-8a),
132.4 (C-4a) ppm.
( ꢄ )-1-(2-Aminoethyl)-1,2,3,4-tetrahydro-6-methoxyisoquinoline dihydrochloride (10b Á 2HCl)
Following the same procedure as for 10a Á 2HCl, reaction of 6.05 g of 6-methoxy dihydroisoquinoline
salt 9bÁ 2HCl (21.5 mmol) and 0.50g of NaBH4 (12.7 mmol) afforded colourless crystals (6.00 g)
of pure 10b Á 2HCl in quantitative yield. Mp: 220ꢁC (Ref. [25] 233ꢁC); TLC (toluene:
MeOH:AcOH ¼ 8:12:1): Rf ¼ 0.75; IR (KBr): ꢁꢁ ¼ 2937ðsÞ, 2843(s), 2637(s), 1614(m), 1590(m),
1
1505(s), 1434(m), 1434(m), 1245(s), 1049(m), 1033(m), 845(m), 819(m) cmÀ 1; H NMR (DMSO-
d6): ꢂ ¼ 2.29 (q, J ¼ 7.2 Hz, 2H, CH2-10, ethyl), 2.92 and 3.06 (dt, J ¼ 16.0, 5.6Hz, 1H, Ha-4, and m,
partly overlapped, 1H, Hb-4), 3.02 (m, 2H, CH2-20, ethyl), 3.16 and 3.38 (m, 1H, Ha-3, and m, 1H, Hb-
3), 3.74 (s, 3H, OCH3), 4.63 (m, 1H, H-1), 6.79 (s, 1H, H-5), 6.87 (dd, J ¼ 8.4, 2.0 Hz, 1H, H-7), 7.22
(d, J ¼ 8.4 Hz, 1H, H-8), 8.24 (bs, 3H, NH-20), 9.61 (bs, 1H, NHa-2), 9.96 (bs, 1H, NHb-2) ppm;
13C NMR (DMSO-d6): ꢂ ¼ 25.0 (C-4), 31.0 (C-10, ethyl), 35.3 (C-20, ethyl), 38.5 (C-3), 51.2 (C-1),
ꢀ
ꢀ
55.2 (OCH3), 113.2 (C-5 ), 113.3 (C-7 ), 123.9 (C-8a), 127.6 (C-8), 133.7 (C-4a), 158.4 (C-6) ppm.
3-Methoxy-ꢀ-nitrostyrene (17b)
17b was prepared according to Ref. [8]. Mp: 90ꢁC (Ref. [8] 90ꢁC); TLC (CHCl3): Rf ¼ 0.61.
( ꢄ )-1-(Cyanomethyl)-1,2,3,4-tetrahydroisoquinoline hydrochloride (18a Á HCl; C11H13ClN2)
To a mixture of 1.87 g of 2a Á HCl (10.0 mmol) and 1.45g of cyanoacetaldehyde diethylacetal
(10.0mmol) in 20 cm3 of chlorobenzene five drops of 6 M ethanolic HCl were added. The reaction
mixture was refluxed for 2 h. During the whole reaction time the eliminated EtOH was removed from
the reaction mixture by destillation. The dark brown, tar-like residue was extracted with 2 N HCl under
slight warming (4ꢃ 20 cm3), the combined aqueous phases were evaporated in vacuo, and the obtained
resin was triturated several times with Et2O to give 0.36 g (17%) of 18a Á HCl. Mp: 185ꢁC; IR (KBr):
ꢁꢁ ¼ 3425ðwÞ, 2938(m), 2744(s), 2637(s), 2468(s), 2247(w), 2191(w), 1590(m), 1525(s), 1466(m),
1
1096(m), 746(s)cmÀ 1; H NMR (DMSO-d6): ꢂ ¼ 3.05 (m, 2H, CH2-4), 3.36 and 3.41 (m, 1H, Ha-
3, and m, 1H, Hb-3), 3.52 (A-part of the ABX-system, JAB ¼ 17.6Hz, JAX ¼ 5.6 Hz, 1H, Ha-10), 3.61
(B-part of the ABX-system, JBA ¼ 17.6Hz, JBX ¼ 6.4 Hz, 1H, Hb-10), 4.90 (X-part of the ABX-system,
J ¼ 5.6 Hz, 1H, H-1), 7.25 (d, J ¼ 7.8 Hz, 1H, H-5), 7.30 (m, 1H, H-7), 7.32 (m, 1H, H-6), 7.40

Potential Inhibitors of the Ergosterol Biosynthesis
923
(d, J ¼ 7.8 Hz, 1H, H-8), 10.32 (bs, 2H, NH-2) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 21.9 (C-10), 24.6 (C-4),
38.3 (C-3), 49.7 (C-1), 117.4 (CN), 126.6 (C-8), 126.8 (C-7), 128.3 (C-6), 129.1 (C-5), 130.2 (C-8a),
132.5 (C-4a) ppm.
( ꢄ )-1,6,7,11b-Tetrahydro-2H-pyrimido[4,3-a]isoquinoline-4(3H)-thione (19a, C12H14N2S)
Amine salt 10 Á 2HCl (4.00 g, 16.3mmol) was dissolved in 20cm3 of H2O, made alkaline with 2 N
NaOH solution and was extracted with CHCl3, dried with Na2SO4, and evaporated to dryness. The
obtained oily amine 10 was dissolved in 30cm3 of EtOH and 10cm3 of CS2 were added under cooling.
Immediately a solid precipitated, the mixture was stirred at room temperature for 1.5 h, then filtered
and washed with little EtOH. The solid was dissolved in 20cm3 of dry DMF and refluxed for 40min,
whereby the liberated H2S was oxidized by discharging successively into 30% H2O2 and 6 N NaOH
solution. After cooling, the reaction mixture was diluted with 160 cm3 of H2O and extracted with
3 ꢃ 20cm3 of CHCl3, dried with Na2SO4, and evaporated to dryness to give 3.36g (95%) of bronze
coloured crystalline 19a. Mp: 191ꢁC; TLC (toluene:MeOH ¼ 1:1): Rf ¼ 0.68; IR (KBr): ꢁꢁ ¼ 3255ðmÞ,
1
2918(w), 2860(w), 1546(s), 1490(s), 1362(m), 1307(m), 1170(s), 1120(w), 750(m) cmÀ 1; H NMR
(CDCl3): ꢂ ¼ 2.03 and 2.52 (ddd, J ¼ 13.2, 10.4, 4.0 Hz, 1H, H-1ax, and dm, J ¼ 13.2Hz, 1H, H-1eq),
2.75 and 3.09 (dt, J ¼ 13.6, 3.2 Hz, 1H, H-7eq, and md, J ¼ 3.2 Hz, 1H, H-7ax), 3.25 and 5.48 (td,
J ¼ 13.6, 3.2 Hz, 1H, H-6ax, and dt, J ¼ 13.6, 3.2 Hz, 1H, H-6eq), 3.35 and 3.45 (dm, J ¼ 13.2Hz, 1H,
H-2eq, and td, J ¼ 13.2, 4.0 Hz, 1H, H-2ax), 4.70 (dd, J ¼ 10.8, 4.0 Hz, 1H, H-11b), 6.65 (bs, 1H, NH-
3), 7.15 (t, J ¼ 6.4 Hz, 1H, H-9), 7.17 (m, 1H, H-10), 7.21 (m, 2H, H-8, H-11) ppm; 13C NMR
(CDCl3): ꢂ ¼ 28.9 (C-1), 29.7 (C-7), 39.8 (C-2), 47.4 (C-6), 55.6 (C-11b), 125.2 (C-9), 126.6 (C-
ꢀ
ꢀ
10), 126.9 (C-8 ), 129.0 (C-11 ), 135.2 (C-11a), 135.4 (C-7a), 177.9 (C-2) ppm.
( ꢄ )-9-Methoxy-1,6,7,11b-tetrahydro-2H-pyrimido[4,3-a]isoquinoline-4(3H)-thione
(19b, C13H16N2OS)
Following the same procedure as described for 19a, the reaction 2.90 g of 6-methoxyisoquinoline 10b
(10.1mmol) and 2.5 cm3 of CS2 (3.17 g, 41.6 mmol) afforded 2.34g (94%) of yellowish 19b. Mp:
202ꢁC; TLC (toluene:MeOH ¼ 1:1): Rf ¼ 0.68; IR (KBr): ꢁꢁ ¼ 3225ðmÞ, 2929(m), 2831(w), 1612(m),
1
1579(m), 1538(s), 1499(s), 1462(m), 1362(m), 1315(s), 1173(s), 1040(m), 813(m) cmÀ 1; H NMR
(CDCl3): ꢂ ¼ 1.99 and 2.47 (m, 1H, H-1ax, and dm, J ¼ 13.6Hz, 1H, H-1eq), 2.70 and 3.43 (dt,
J ¼ 13.2, 2.8 Hz, 1H, H-7eq, and td, J ¼ 13.2, 2.8 Hz, 1H, H-7ax), 3.26 and 5.42 (dd, J ¼ 13.2,
2.8 Hz, 1H, H-6ax, and dt, J ¼ 13.2, 2.8 Hz, 1H, H-6eq), 3.31 and 3.41 (dm, J ¼ 13.6Hz, 1H, H-2eq,
and td, J ¼ 13.6, 3.2Hz, 1H, H-2ax), 3.78 (s, 3H, OCH3), 4.64 (dd, J ¼ 10.8, 4.0 Hz, 1H, H-11b), 6.48
(bs, 1H, NH-3), 6.66 (d, J ¼ 2.4 Hz, 1H, H-8), 6.77 (dd, J ¼ 8.4, 2.4Hz, 1H, H-10), 7.05 (d, J ¼ 8.4 Hz,
1H, H-11) ppm; 13C NMR (CDCl3): ꢂ ¼ 29.3 (C-7), 29.6 (C-1), 39.6 (C-2), 47.3 (C-6), 55.0 (C-11b ),
ꢀ
ꢀ
177.7 (C-4) ppm.
55.3 (OCH3 ), 113.0 (C-10), 113.8 (C-8), 126.3 (C-11), 127.7 (C-11a), 136.6 (C-7a), 158.3 (C-9),
( ꢄ )-1,6,7,11b-Tetrahydro-N 4-nitro-2H-pyrimido[4,3-a]isoquinolin-4(3H)-imine
(20a, C12H14N4O2), ( ꢄ )-1,6,7,11b-Tetrahydro-2H-pyrimido[4,3-a]isoquinolin-4-amine
hydrochloride (22a Á HCl, C12H16ClN3), and ( ꢄ )-1,6,7,11b-Tetrahydro-2H-
pyrimido[4,3-a]isoquinolin-4(3H)-one (24a, C12H14N2O)
20a was synthesized according to the method described in Ref. [17]. Nitroguanidine (0.63 g,
4.80mmol) was dissolved in 8 cm3 of H2O containing 0.54 g of KOH (9.60mmol), then a solution
of diamine salt 10a Á 2HCl (1.20 g, 4.80mmol) in 8 cm3 of H2O was added with stirring. A thick sludge
formed, which was heated at 70ꢁC over 50 min until the sludge dissolved completely and gas evolution
ceased. After cooling of the reaction mixture and dilution with 30cm3 of 2 N HCl the precipitated solid

¨
E. Goßnitzer and A. Punkenhofer
924
was filtered off and washed with water. The solid contained cyclic urea 24a and nitrimino compound
20a which were separated by dissolving 20a with 3 ꢃ 10 cm3 of ethyl acetate and filtering off 0.11g
(11%) of insoluble 24a with mp: 133ꢁC (Ref. [26] 149–151ꢁC) and TLC (MeOH:toluene ¼ 1:1):
Rf ¼ 0.52. The ethyl acetate filtrate was dried with Na2SO4, filtered and concentrated in vacuo to give
0.63g (53%) of nitrimino compound 20a as yellow resin: TLC (MeOH:toluene ¼ 1:1): Rf ¼ 0.69. The
aqueous filtrate was extracted with 3 ꢃ 10 cm3 of CHCl3, the organic layer was dried with Na2SO4 and
it was evaporated to dryness affording 0.37 g (32%) of 22a Á HCl; mp 168ꢁC; (NMR data are identical
to that of the hydroiodide 22a Á HI).
20a: IR (KBr): ꢁꢁ ¼ 3262ðmÞ, 2927(m), 1655(s), 1595(s), 1578(s), 1553(s), 1422(s), 1324(m),
1
1264(s), 1136(s), 1040(m), 756(m)cmÀ 1; H NMR (CDCl3): ꢂ ¼ 1.96 and 2.59 (m, 1H, H-1ax, and
dq, J ¼ 13.6, 4.0 Hz, 1H, H-1eq), 2.72 and 2.95 (dt, J ¼ 12.8, 3.6 Hz, 1H, H-7eq, and td, J ¼ 12.8,
3.6 Hz, 1H, H-7ax), 3.09 and 4.85 (td, J ¼ 12.8, 3.6 Hz, 1H, H-6ax, and dt, J ¼ 12.8, 3.6 Hz, 1H, H-6eq),
3.58 (m, 2H, CH2-2), 4.76 (dd, J ¼ 10.8, 4.0 Hz, 1H, H-11b), 7.10 (d, J ¼ 8.4 Hz, 1H, H-8), 7.14 (d,
J ¼ 8.4 Hz, 1H, H-11), 7.19 (m, 2H, H-9, H-10), 9.85 (s, 1H, NH-3) ppm; 13C NMR (CDCl3): ꢂ ¼ 28.7
ꢀ
ꢀ
(C-1), 28.9 (C-7), 38.0 (C-2), 42.3 (C-6), 54.4 (C-11b), 125.1 (C-11), 126.9 (C-9 ), 127.4 (C-10 ),
129.1 (C-8), 134.0 (C-11a), 134.7 (C-7a), 154.4 (C-4) ppm.
24a: IR (KBr): ꢁꢁ ¼ 3289ðmÞ, 3198(m), 3057(m), 2962(m), 1649(s), 1513(s), 1451(m), 1366(m),
1
1155(w), 757(m) cmÀ 1; H NMR (DMSO-d6): ꢂ ¼ 1.64 and 2.49 (ddd, J ¼ 11.6, 5.2, 3.6 Hz, 1H, H-
1ax, and md, partly overlapped, J ¼ 3.6 Hz, 1H, H-1eq), 2.66 and 2.71 (m, 1H, H-7ax, and m, partly
overlapped, 1H, H-7eq), 2.75 and 4.45 (m, partly overlapped, 1H, H-6ax, and m, 1H, H-6eq), 3.13 and
3.25 (m, 1H, H-2eq, and td, J ¼ 11.6, 3.6 Hz, 1H, H-2ax), 4.61 (dd, J ¼ 10.8Hz, 3.6 Hz, 1H, H-11b),
6.40 (bs, 1H, NH-3), 7.13 (m, 1H, H-9), 7.17 (d, partly overlapped, 1H, H-8), 7.21 (td, J ¼ 7.6, 2.0 Hz,
1H, H-10), 7.28 (d, J ¼ 8.4 Hz, 1H, H-11) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 28.9 (C-7) , 30.2 (C-1),
ꢀ
ꢀ
37.9 (C-2), 38.9 (C-6), 53.9 (C-11b), 125.5 (C-11), 126.1 (C-9 ), 126.2 (C-10 ), 128.8 (C-8), 134.9
(C-11a), 137.2 (C-7a), 155.0 (C-4) ppm.
( ꢄ )-1,6,7,11b-Tetrahydro-4-methylthio-2H-pyrimido[4,3-a]isoquinoline hydroiodide
(21a Á HI, C13H17IN2S)
Thion 19a (7.25 g, 33.2 mmol) and 6.00 g of CH3I (42.3mmol) were refluxed in 90cm3 of MeOH
3
˚
(dried with molecular sieve, 3 A) for 1 h. On cooling and dilution of the reaction mixture with 250 cm
of dry Et2O, 10.9g (91%) of pure yellowish 21a Á HI precipitated. Mp: 208ꢁC (decomp.); TLC
(toluene:MeOH ¼ 1:1): Rf ¼ 0.48; IR (KBr): ꢁꢁ ¼ 3251ðmÞ, 2971(w), 2931(w), 1600(s), 1578(m),
1
1516(m), 1428(m), 1208(m), 1190(m), 756(m) cmÀ 1; H NMR (DMSO-d6): ꢂ ¼ 1.93 and 2.72 (m,
1H, H-1ax, and dq, J ¼ 12.0, 4.0 Hz, 1H, H-1eq), 2.67 (s, 3H, SCH3), 2.91 and 3.00 (dt, J ¼ 12.8, 4.4Hz,
1H, H-7eq, and td, J ¼ 12.8, 4.4 Hz, 1H, H-7ax), 3.55 (m, 2H, CH2-2), 3.62 and 4.12 (td, J ¼ 12.8,
4.4 Hz, 1H, H-6ax, and dt, J ¼ 12.8, 4.4 Hz, 1H, H-6eq), 4.97 (dd, J ¼ 10.8, 4.0Hz, 1H, H-11b), 7.26 (m,
1H, H-9), 7.28 (m, 1H, H-10), 7.30 (dd, J ¼ 7.8, 2.0 Hz, 1H, H-8), 7.37 (d, J ¼ 7.8 Hz, 1H, H-11), 9.23
(s, 1H, NH-3) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 14.3 (CH3), 26.7 (C-1), 27.9 (C-7), 40.1 (C-2), 46.6 (C-
6), 55.8 (C-11b), 125.5 (C-11), 126.9 (C-9), 127.3 (C-10), 128.3 (C-8), 133.9 (C-7a), 134.3 (C-11a),
164.1 (C-4) ppm.
( ꢄ )-1,6,7,11b-Tetrahydro-9-methoxy-4-methylthio-2H-pyrimido[4,3-a]isoquinoline
hydroiodide (21b Á HI, C14H19IN2OS)
Following the same procedure as described for 21a Á HI, reaction of 1.00 g of 19b (4.04 mmol) and
1.00g of CH3I (7.04 mmol) afforded 1.24 g (78%) of yellowish 21b Á HI. Mp: 225ꢁC (decomp.); TLC
(toluene:MeOH ¼ 1:2): Rf ¼ 0.10; IR (KBr): ꢁꢁ ¼ 3284ðmÞ, 2962(m), 2932(w), 1610(s), 1519(m),
1
1508(s), 1373(m), 1303(s), 1242(m), 1030(m), 844(m)cmÀ 1; H NMR (DMSO-d6): ꢂ ¼ 1.88 and
2.68 (m, 1H, H-1ax, and md, partly overlapped, J ¼ 4.4 Hz, 1H, H-1eq), 2.66 (s, 3H, SCH3), 2.90

Potential Inhibitors of the Ergosterol Biosynthesis
925
and 2.99 (m, 1H, Ha-7, and m, 1H, Hb-7), 3.53 (m, 2H, CH2-2), 3.62 and 4.06 (td, J ¼ 12.8, 4.4Hz, 1H,
H-6ax, and dt, J ¼ 12.8, 4.4 Hz, 1H, H-6eq), 3.74 (s, 3H, OCH3), 4.89 (dd, J ¼ 10.8, 4.4 Hz, 1H, H-11b),
6.83 (d, J ¼ 2.0 Hz, 1H, H-8), 6.87 (dd, J ¼ 8.8, 2.0 Hz, 1H, H-10), 7.27 (d, J ¼ 8.8 Hz, 1H, H-11), 9.21
(s, 1H, NH-3) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 14.4 (SCH3), 26.7 (C-1), 28.1 (C-7), 40.0 (C-2), 46.6
(C-6), 55.2 (C-11b), 55.5 (OCH3), 112.9 (C-8), 113.0 (C-10), 126.3 (C-11a), 126.6 (C-11), 135.4
(C-7a), 158.2 (C-9), 164.0 (C-4) ppm.
( ꢄ )-1,6,7,11b-Tetrahydro-2H-pyrimido[4,3-a]isoquinolin-4-amine hydroiodide
(22a Á HI, C12H16IN3)
Isothiouronium salt 21a Á HI (1.80 g, 5.00mmol) was suspended in 30cm3 of MeCN and refluxed for
2.5 h, while dry NH3 was passed through the solution. The liberated CH3SH was discharged succes-
sively into 20% KMnO4 and 6 N NaOH solution. After cooling, the solvent was removed in vacuo. The
obtained solid was triturated with Et2O and filtered to yield 1.49 g (91%) of pure 22a Á HI. Mp: 168ꢁC;
TLC (CH2Cl2:MeOH: Et3N ¼ 16:4:1): Rf ¼ 0.83; IR (KBr): ꢁꢁ ¼ 3275ðmÞ, 3124(s), 2880(w), 1643(s),
1
1618(s), 1590(s), 1393(m), 1370(m), 1329(m), 1145(w), 1124(w), 1043(w), 778(m)cmÀ 1; H NMR
(CDCl3): ꢂ ¼ 1.81 and 2.62 (m, 1H, H-1ax, and dq, J ¼ 13.6, 4.0 Hz, 1H, H-1eq), 2.86 and 3.08 (dt,
J ¼ 13.2, 4.2 Hz, 1H, H-7eq, and td, J ¼ 13.2, 4.2 Hz, 1H, H-7ax), 3.41 (m, 2H, CH2-2), 3.62 and 4.16
(m, 1H, H-6ax, and dt, J ¼ 12.8, 4.2 Hz, 1H, H-6eq), 4.77 (dd, J ¼ 10.4Hz, 4.0 Hz, 1H, H-11b), 7.13
(d, J ¼ 8.4Hz, 1H, H-8), 7.28 (m, 2H, H-9, H-10), 7.33 (d, J ¼ 8.4 Hz, 1H, H-11), 7.51 (bs, 2H,
NH-2), 8.04 (bs, 1H, NH-3) ppm; 13C NMR (CDCl3): ꢂ ¼ 27.7 (C-1), 28.0 (C-7), 37.0 (C-2), 42.9
ꢀ
ꢀ
(C-6), 53.5 (C-11b), 125.2 (C-11), 126.7 (C-10 ), 127.0 (C-9 ), 128.4 (C-8), 134.2 (C-7a), 135.4
(C-11a), 153.2 (C-4) ppm.
( ꢄ )-1,6,7,11b-Tetrahydro-9-methoxy-2H-pyrimido[4,3-a]isoquinolin-4-amine
hydrochloride (22b Á HCl, C13H18ClN3O)
Dry NH3 was passed through the suspension of 1.00 g of 21b Á HI (2.56 mmol) in 10cm3 of MeOH at
reflux for 3 h. The reaction mixture became clear and the liberated CH3SH was discharged successively
into 20% KMnO4 and 6 N NaOH solution. After cooling, the solvent was removed in vacuo. The
obtained residue was dissolved in CHCl3. On trituration of this solution with Et2O solid 22b Á HI
precipitated. For purification the crude 22b Á HI was treated with 6 N NaOH solution, extracted with
3 ꢃ 10cm3 of CHCl3, it was dried with Na2SO4 and evaporated. Addition of 3 cm3 6 M ethanolic HCl
to the obtained oil of 22b and evaporation yielded 0.89g (97%) of hygroscopic 22b Á HCl. Mp: 85ꢁC
(decomp.); TLC (CH2Cl2:MeOH:Et3N ¼ 16:4:1): Rf ¼ 0.30; IR (KBr): ꢁꢁ ¼ 3304ðmÞ, 2933(m),
1643(m), 1611(s), 1504(m), 1302(w), 1242(m), 1034(m), 802(w) cmÀ 1 1H NMR (DMSO-d6):
;
ꢂ ¼ 1.75 and 2.55 (m, 1H, H-1ax, and dd, J ¼ 12.8, 3.2 Hz, 1H, H-1eq), 2.81 and 2.92 (dt, J ¼ 13.6,
4.0 Hz, 1H, H-7eq, and m, 1H, H-7ax), 3.24 and 3.87 (td, J ¼ 13.6, 4.0 Hz, 1H, H-6ax, and dt, J ¼ 13.6,
4.0 Hz, 1H, H-6eq), 3.30 (m, 2H, CH2-2), 3.75 (s, 3H, OCH3), 4.67 (dd, J ¼ 10.8, 4.4 Hz, 1H, H-11b),
6.76 (d, J ¼ 2.4 Hz, 1H, H-8), 6.83 (dd, J ¼ 8.4, 2.4 Hz, 1H, H-10), 7.20 (bs, 2H, NH-4), 7.23 (d,
J ¼ 8.4 Hz, 1H, H-11), 7.71 (s, 1H, NH-3) ppm; 13C NMR (DMSO-d6): ꢂ ¼ 27.6 (C-1), 27.9 (C-7), 36.9
(C-2), 43.0 (C-6), 53.1 (C-11b), 55.4 (OCH3), 113.7 (C-10), 114.5 (C-8), 125.8 (C-11a), 126.2 (C-11),
135.5 (C-7a), 153.2 (C-4), 156.2 (C-9) ppm.
( ꢄ )-4-Ethoxy-1,6,7,11b-tetrahydro-2H-pyrimido[4,3-a]isoquinoline (23a, C14H18N2O)
The diamine 10a was set free from 0.45g of 10a Á 2HCl (1.80mmol) with 2 N NaOH solution and
extracted with 3 ꢃ 30 cm3 of toluene. After drying the toluene phase with Na2SO4 and filtration 0.66g
of tetraethyl orthocarbonate (3.40 mmol) and 0.06g of capronic acid (0.52 mmol) were added accord-
ing to Ref. [16]. The reaction mixture was heated to maintain a slow rate of distillation (vapor

¨
E. Goßnitzer and A. Punkenhofer
926
temperature first 76ꢁC, then 115ꢁC) until EtOH and half of the toluene were removed (ꢂ30min).
Then, the residue was evaporated to dryness. The obtained resin was dissolved in 2 cm3 of ethyl acetate
and filtered through a short silica gel column (ethyl acetate:diethylamine¼ 9:1) to afford, after vacuum
1
drying, 0.13 g (31%) of 23a as yellow resin. TLC (ethyl acetate:diethylamine ¼ 9:1): Rf ¼ 0.49; H
NMR (CDCl3): ꢂ ¼ 1.25 and 4.07 (t, J ¼ 7.2 Hz, 3H, and q, J ¼ 7.2 Hz, 2H, CH3CH2O), 1.77 and 2.33
(m, 1H, H-1ax, and dq, J ¼ 13.2, 4.0Hz, 1H, H-1eq), 2.62 and 2.90 (dm, J ¼ 11.6 Hz, 1H, H-7eq, and td,
J ¼ 11.6, 4.4Hz, 1H, H-7ax), 2.96 and 4.27 (td, J ¼ 11.6, 4.4 Hz, 1H, H-6ax, and m, 1H, H-6eq), 3.43
(m, 2H, CH2-2), 4.53 (dd, J ¼ 10.0, 4.0 Hz, 1H, H-11b), 7.07 (t, J ¼ 7.8Hz, 1H, H-8), 7.13 (m, 3H, H-
9, H-10, H-11) ppm; 13C NMR (CDCl3): ꢂ ¼ 14.5 (CH3), 29.3 (C-1), 30.4 (C-7), 41.2 (C-6), 42.8 (C-2),
54.6 (C-11b), 61.3 (OCH2), 125.2 (C-8), 126.2 (C-9, C-10), 128.8 (C-11), 134.9 (C-11a), 137.5 (C-7a),
153.1 (C-4) ppm.
Antifungal Testing
The antifungal testing was performed according to the National Committee for Clinical Laboratory
Standards (NCCLS) microdilution procedure M38-P [22]. The eight fungal strains were dispersed in
Sabouraud broth supplemented with 2% glucose. For the yeasts Candida albicans NFI 0124, Candida
albicans NFI 2103, Saccharomyces cerevisiae NFI 3201, and Cryptococcus neoformans NFI 3102
the MIC testing was performed at a concentration of 1 ꢃ 103 CFU Á cmÀ 3. The dermatophytes
Trichophyton mentagrophytes NFI 5606 and Trichophyton rubrum NFI 5182 were diluted to
5 ꢃ 103 CFU Á cmÀ 3 and the Aspergillus fumigatus NFI 0159 and Aspergillus fumigatus NFI 0240
strains were tested at 1 ꢃ 104 CFU Á cmÀ 3. In every assay itraconazole was included as a control drug
tested in a range from 4 to 0.008 mg Á cmÀ 3. The test compounds were diluted in DMSO at a
concentration of 12.8mgÁ cmÀ 3. For the antifungal testing a serial 2-fold dilution-row was performed.
Acknowledgment
¨
Financial support from the Austrian Fonds zur Forderung der wissenschaftlichen Forschung (P14758-
CHE) is gratefully acknowledged. The authors are grateful to Prof. W. Wendelin for helpful discussions
¨
and Ing. K. Ploschberger for his assistance in the preparation of some intermediates. We thank the
Novartis Research Institute, Vienna, in particular Dr. N. Ryder for the granting of test facilities and
Dr. B. Favre and Dr. B. Hofbauer for performing the antifungal tests.
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