Novel fluorescent reactive dyes as intermediates for the preparation of UV and vis wavelength fluorescent probes

Article abstract of DOI:10.1007/PL00013476

To prepare reactive dyes matching the optical properties of 2-(1,1-dicyano-propenyl-2)-6-dimethylaminonaphthalene (DDNP), 2-ethylaminoethanol or 4-piperidinemethanol were used in a Bucherer reaction with 1-(6-hydroxy-2-naphthyl)-1-ethanone. The two amines were chosen to mimic the dimethylamino group's steric and electronic (inductive) effects and to provide a reactive site for ligand attachment. The intermediate hydroxy derivatives were transformed into fluorescent reactive p-toluenesulfonic acid esters which in turn were conjugated to the test ligand spiperone. Knoevenagel condensation with malononitrile afforded Vis wavelength fluorescent probes.

Full text of DOI:10.1007/PL00013476

Monatshefte fuÈr Chemie 129, 777±786 (1998)
Novel Fluorescent Reactive Dyes as
Intermediates for the Preparation of UV and
Vis Wavelength Fluorescent Probes
1
2
ꢀ1;Ã
ꢀ
Andrej Petric , Tatjana Spes , and Jorge R. Barrio
1
Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana,
Slovenia
2
Department of Molecular and Medical Pharmacology and Laboratory of Structural Biology and
Molecular Medicine, UCLA, School of Medicine, Los Angeles, California 90095, USA
Summary. To prepare reactive dyes matching the optical properties of 2-(1,1-dicyano-propenyl-2)-
6-dimethylaminonaphthalene (DDNP), 2-ethylaminoethanol or 4-piperidinemethanol were used in a
Bucherer reaction with 1-(6-hydroxy-2-naphthyl)-1-ethanone. The two amines were chosen to mimic
the dimethylamino group's steric and electronic (inductive) effects and to provide a reactive site for
ligand attachment. The intermediate hydroxy derivatives were transformed into ¯uorescent reactive
p-toluenesulfonic acid esters which in turn were conjugated to the test ligand spiperone.
Knoevenagel condensation with malononitrile afforded Vis wavelength ¯uorescent probes.
Keywords. Bucherer reaction; Fluorescent dyes; Fluorescent probes; Spiperone conjugates.
Neue reaktive Fluoreszenzfarbstoffe als Zwischenprodukte zur Herstellung von
Fluoreszenzindikatoren im ultravioletten und sichtbaren Bereich
Zusammenfassung. Zur Herstellung reaktiver Farbstoffe mit optischen Eigenschaften, die jenen von
2-(1,1-Dicyanopropenyl-2)-6-dimethylaminonaphthalin (DDNP) entsprechen, wurden 2-Ethyl-
aminoethanol bzw. 4-Piperidinmethanol in einer Bucherer-Reaktion mit 1-(6-Hydroxy-2-
È
naphthyl)-1-ethanon umgesetzt. Die beiden Amine wurden gewahlt, um die sterischen und
elektronischen (induktiven) Effekte der Dimethylaminogruppe zu imitieren und zugleich ein
reaktives Zentrum fuÈr Substituitionsreaktionen bereitzustellen. Die als Zwischenprodukte auftre-
È
È
tenden Hydroxyderivate wurden in reaktive ¯uoreszierende p-Toluolsulfonsaureester ubergefuhrt,
È
die ihrerseits mit dem Testliganden Spiperon umgesetzt wurden. Durch Knoevenagel-Kondensation
È
È
mit Malonsaurenitril wurden Fluoreszenzindikatoren fur den sichtbaren Bereich erhalten.
Introduction
After the discovery of the novel polarity/viscosity sensitive Vis wavelength
¯uorescent compound 2-(1,1-dicyanopropenyl-2)-6-dimethylaminonaphthalene
(DDNP) [1] we set out to modify its structure in order to prepare a reactive dye
Ã
Corresponding author

Ï
A. Petric et al.
778
which would inherit DDNP's unique optical properties and would allow for the
preparation of new ¯uorescent probes for the probing of biological systems. In this
work we chose 2-ethylaminoethanol and 4-piperidinemethanol as substitutes for
dimethylamine in the synthesis of these analogs. Both contain an amine nitrogen,
required for the production of the ¯uorophore, and a hydroxyalkyl functional group
which can be effectively activated for nucleophilic substitution by a ligand of
choice. To test this approach, spiperone, a highly potent ligand for the dopamine D2
receptors, was chosen as the ligand.
Results and Discussion
The synthetic approach used in the preparation of 2-acetyl-6-N,N-dimethyl-
aminonaphthalene (ADMAN) [1], utilizing the corresponding lithium amide and 2-
acetyl-6-methoxynaphthalene, could not be employed with 2-ethylaminoethanol
and 4-piperidinemethanol. The competing faster reaction of dimethylamine
liberated in the decomposition of hexamethylphosphoric amide [2] lead to
exclusive formation of ADMAN, irrespective of the presence of the intended amine.
This prompted us to resort to the Bucherer reaction [3]. Starting from 1-(6-
hydroxy-2-naphthyl)-1-ethanone (1) and using 2-ethylaminoethanol or 4-piper-
idine-methanol as substrates in the presence of sodium hydrogensulfate resulted in
relatively poor yields of the desired naphthalene derivatives 2 and 3 (Fig. 1).
Fig. 1.
In order to conjugate spiperone to the naphthalene ring via a dialkylamino
spacer, we ®rst activated the hydroxy group in 2 for nucleophilic displacement by
transforming it into the tosylate 4, a reactive dye which can be excited in the UV
range (Scheme 1). The latter was then subjected to reaction with spiperone ketal
under phase transfer reaction conditions. We isolated two products (5 and 6) in a
ratio of approximately 1:2, exhibiting the same molecular mass but different NMR
spectra. One of the characteristic differences that led to the assignment of the
respective structures was the subspectrum resulting from the ethylene group
between the naphthalene and spiperone moieties. In 5, we found two triplets at 4.52
and 3.85 ppm, corresponding to a OCH2CH2N structural element. On the other
hand, in 6 analogous signals were found overlapping at 3.71±3.81 ppm, consistent
with a NCH2CH2N moiety [4]. The structures were further supported by chemical
shift changes of a well separated singlet, corresponding to the protons at the
spiperone C-3 position. In spiperone or its N-2 alkylated derivatives such signals
appear at 4.68±4.75 ppm [5]. In 6 the corresponding signal appeared in the
expected range (4.68 ppm), whereas it was shifted down®eld to 4.99 ppm in 5,

UV and Vis Fluorescent Probes
779
Scheme 1
consistent with imide (5) and amide (6) structures. Using the Knoevenagel reaction
with malononitrile, we transformed compound 6 into 7 which upon acid catalyzed
deprotection of the spiperone moiety gave the new Vis wavelength ¯uorescent
probe 8.
In a similar synthetic sequence we attached the spiperone moiety to the
¯uorophore via a 4-methylpiperidine spacer. First, the 4-hydroxymethyl group in 3
was activated by conversion into the tosylate 9, followed by the reaction with
spiperone under phase transfer conditions at room temperature. Two products (10
and 11) exhibiting the same molecular mass were isolated in an approximately 1:4
ratio (Scheme 2). Based on characteristic differences in NMR chemical shifts of
the signals for the C-3 protons in the spiperone subspectra (singlet, 4.97 and
4.71 ppm, resp.) and the exocyclic methylene group protons in the piperidylmethyl
group subspectra (doublet, 4.19 and 3.35 ppm, resp.) [6], we assigned structures 10
and 11 to the two products. Intermediate 11 was subjected to a Knoevenagel
reaction with malononitrile to yield the Vis ¯uorescent intermediate 12 which upon
acid catalyzed deprotection of the spiperone moiety yielded the Vis ¯uorescent
probe 13. The proposed structures of compounds 2 through 13 were also con®rmed
by elemental analyses or HRMS.
The optical properties of compounds 6, 7, 11, and 12 are presented and
compared with those of DNNP and ADMAN in Table 1. Chloroform and methanol
were chosen as the solvents to detect solvent polarity dependent differences in
absorption, ¯uorescence excitation, and emission (Fig. 2). The results support our

Ï
A. Petric et al.
780
Scheme 2
Table 1. Absorption (ꢀmax (nm)), ¯uorescence excitation (ꢀex (nm)) and emission maxima (ꢀem (nm))
Solvent
ADMAN [1]
6
11
DDNP [1]
7
12
ꢀmax
ꢀex
358
360
436
374
359
430
370
354
443
444
450
548
437
436
525
433
CHCl3
418, 443
538
ꢀem
ꢀmax
ꢀex
366
365
506
371
371
426
428
610
430
438
419
MeOH
362, 379 357
487 494
395, 440
ꢀem
558, 565 563
assumption that formal replacement of the dimethyl amino group in ADMAN and
DDNP by a substituted diethylamino- or 4-methylpiperidino group should not
dramatically change the optical properties of the ¯uorophore. Both ADMAN
(compounds 6 and 11) and DDNP derivatives (compounds 7 and 12) match the
properties of the parent compounds well. However, the excitation and emission
maxima are somewhat blueshifted. This indicates that both amines used disturb the

UV and Vis Fluorescent Probes
781
Fig. 2. Fluorescence excitation (Ð) and emission (Ð) spectra; (A): in CHCl3, (B): in MeOH
electronic density distribution of the parent ¯uorophores, resulting in ¯uorescence
changes.
Conclusions
We have shown that ligands possessing at least one nucleophilic center where
alkylation does not result in signi®cant degradation of binding properties (e.g.
spiperone) can be effectively conjugated with tosylates 4 and 9 to produce UV
¯uorescent probes maintaining the biological properties of the parent ligand. Due
to amide/imide tautomerism, two competing nucleophilic centers are present in the
spiperone ketal molecule leading to the formation of mixtures of O- and N-
alkylated products in reactions with 4 and 9. If the chosen ligand is unaffected
under Knoevenagel conditions with malononitrile, or it can be suitably protected,
Vis wavelength ¯uorescent probes can be prepared. The ¯uorescent properties of
these compounds resemble those of ADMAN and DDNP, supporting the validity of
the described approach to the preparation of novel UV and Vis ¯uorescent dyes for
the probing of biological systems.
Experimental
1
NMR spectra were obtained on Bruker AM 360 WB or DPX 300 spectrometers. H chemical shifts
are reported in ppm down®eld from TMS as internal standard. Deuteriochloroform was used as the
solvent unless stated otherwise. Fluorescence spectra were measured on a Perkin Elmer LS 50B
luminescence spectrometer. Melting points were determined on a Electrothermal melting point
apparatus and are uncorrected. Elemental analyses were performed at the Faculty of Chemistry and

Ï
A. Petric et al.
782
Chemical Technology, University of Ljubljana, or by Galbraith Laboratories Inc., Knoxville, TN.
Mass spectra were recorded by Dr. Bogdan Kralj at the National Center for Mass Spectrometry of the
Republic of Slovenia or by Dr. Kym Faull at the mass spectrometry facility at the Department of
Chemistry, University of California at Los Angeles. Radial chromatography was performed on a
Chromatotron (Harrison Research, 840 Moana Court, Palo Alto, CA 94306). The rotors were
prepared as recommended by Harrison Research using EM Silica Gel (Cal. No. 7749±3). Solvents
and reagents were from Fisher, Aldrich, or Fluka and were used as received unless noted otherwise.
The elemental analysis data compared satisfactorily with the calculated values.
1-(6-Hydroxy-2-naphthyl)-1-ethanone (1)
In a 3 l two-neck round bottom ¯ask equipped with a re¯ux condenser and a dropping funnel, 2 l of
HCl (d ˆ 1.16) were stirred and heated to boiling. A solution of 6.06 g (30.3 mmol) of 1-(6-methoxy-
2-naphthyl)-1-ethanone [9] in a minimum amount of dichloromethane was added, and the mixture
was stirred and heated at re¯ux for 2 h. The hot solution was ®ltered through a mineral wool plug to
remove the oily residue. The solid that separated after cooling was ®ltered through a glass frit and
dissolved in 130 ml of ethyl acetate. The solution was washed with brine, dried over anhydrous
magnesium sulfate, and evaporated to give 5 g (89%) 1. After recrystallization from ethyl acetate the
sample melted at 173.5±177ꢀC (Ref. [10]: 170±171ꢀC).
1H NMR: ꢁ ˆ 2.71 (s, 3H, CH3), 7.18 (dd, 1H, 7-H), 7.19 (d, 1H, 5-H), 7.72 (d, 1H, 4-H), 7.88 (d,
1H, 8-H), 8.00 (dd, 1H, 3-H), 8.40 (d, 1H, 1-H) ppm; J1;3 ˆ 2 Hz, J3;4 ˆ 8.5 Hz, J5;7 ˆ 2 Hz,
J7;8 ˆ 8.6 Hz.
1-6-(Ethyl-(2-hydroxyethyl)-amino)-2-naphthyl-1-ethanone (2; C16H19NO2)
A mixture of 1-(6-hydroxy-2-naphthyl)-1-ethanone (1, 744 mg, 3.92 mmol), sodium hydrogensulfate
(1.66 g, 16 mmol), 2-ethylaminoethanol (2 ml), and water (5 ml) was heated in a steel bomb at 130±
140ꢀC for 3 days. After cooling, the mixture was distributed between water and ethyl acetate, and the
organic layer was washed with brine, dried, and evaporated. The residue was dissolved in acetone
and applied onto a 4 mm dry silica plate for radial chromatography. The plate was eluted with a 1:1
mixture of petroleum ether and ethyl acetate. Appropriate fractions were collected and evaporated to
give 125 mg (12%) of 2. The product melted at 82±85ꢀC.
1H NMR: ꢁ ˆ 1.27 (t, 3H, CH2CH3), 1.52 (s, 1H, OH), 2.67, (s, 3H, COCH3), 3.56 (t, 2H,
NCH2CH2O), 3.63 (t, 2H, NCH2CH2O), 3.91 (q, 2H, CH2CH3), 6.93 (d, 1H, 5-H), 7.19 (dd, 1H, 7-
H), 7.62 (d, 1H, 4-H), 7.80 (d, 1H, 8-H), 7.92 (dd, 1H, 3-H), 8.30 (d, 1H, 1-H) ppm; J1;3 ˆ 3 Hz,
J3;4 ˆ 10 Hz, J5;7 ˆ 3 Hz, J7;8 ˆ 10 Hz, J
) ˆ 5.9 Hz, JꢁNCH CH O† ˆ 5.9 Hz.
ꢁCH2CH3
2
2
1-6-(4-(Hydroxymethyl)-piperidino)-2-naphthyl-1-ethanone (3; C18H21NO2)
A mixture of 1-(6-hydroxy-2-naphthyl)-1-ethanone (1, 653 mg, 3.5 mmol), sodium hydrogensulfate
(1.6 g, 15.5 mmol), 4-piperidylmethanol [7] (2 g, 17.6 mmol), and water (6 ml) was heated in a steel
bomb at 135±142ꢀC for 16 days. After cooling, the reaction mixture was extracted with ethyl acetate.
Some product still remained in the residue, so it was further extracted with 5% methanol in
dichloromethane. The organic extracts were combined, dried, and evaporated. The residue was
chromatographed by radial chromatography (2 mm silica, 2% methanol in dichloromethane) to yield
139 mg (14%) of 3. After recrystallization from ethyl acetate the compound melted at 180±182ꢀC.
1H NMR: ꢁ ˆ 1.44 (dddd, 2H, 30a-H, 50a-H), 1.76 (m, 1H, 40a-H), 1.91 (bd, 2H, 30e-H, 50e-H),
2.68 (s, 3H, COCH3), 2.89 (ddd, 2H, 20a-H, 60a-H), 3.58 (d, 2H, OCH2), 3.94 (bd, 2H, 20e-H, 60e-H),
7.10 (d, 1H, 5-H), 7.32 (dd, 1H, 7-H), 7.66 (d, 1H, 4-H), 7.80 (d, 1H, 8-H), 7.94 (dd, 1H, 3-H), 8.32
0
0
0
0
0
0
0
0
0
0
0
0
(d, 1H, 1-H) ppm; J3 a,3 e ˆ J5 a,5 e ˆ 12.5 Hz, J2 a,3 a ˆ J6 a,5 a ˆ 12.5 Hz, J3 a,4 a ˆ J5 a,4 a ˆ 12.5 Hz,

UV and Vis Fluorescent Probes
783
0
0
0
0
0
0
0
0
0
0
0
0
J2 e,3 a ˆ J6 e,5 a ˆ 4.0 Hz, J2 a,2 e ˆ J6 a,6 e ˆ 12.5 Hz, J2 a,3 e ˆ J6 a,5 e ˆ 2.6 Hz, J4a,OCH ˆ 6.4 Hz,
2
J1,3 ˆ 1.9 Hz, J3,4 ˆ 8.9 Hz, J5;7 ˆ 2.3Hz, J7;8 ˆ 9.0 Hz.
6-Acetyl-2-(ethyl-2-((4-methylphenyl)-sulfonyloxy)-ethylamino)-naphthalene (4; C23H25NO4S)
A solution of 2 (125 mg, 0.486 mmol) in pyridine (3.5 ml) was cooled to ꢂ15ꢀC, and p-
toluenesulfonic anhydride (252 mg, 0.81 mmol) was added with stirring under argon. The reaction
mixture was allowed to warm up slowly to room temperature, and stirring was continued for 24 h.
Because TLC (silica, 10% ethyl acetate in petroleum ether) revealed that starting material was still
present, more p-toluensulfonic anhydride (252 mg, 0.81 mmol) was added, and stirring was
continued for additional 24 h. The mixture was then cooled in an ice-water bath and distributed
between brine and ether. The organic layer was dried and evaporated to leave an oily residue. The
product (4) was isolated by radial chromatography (1 mm silica, dichloromethane) in 30% yield.
HRMS: calcd. for C23H25NO4S: 411.1504, found: 411.1514; 1H NMR: ꢁ ˆ 1.25 (t, 3H,
CH2CH3), 2.33 (s, 3H, Ph-CH3), 2.67 (s, 3H, COCH3), 3.49 (q, 2H, CH2CH3), 3.75 (t, 2H,
NCH2CH2O), 4.25 (t, 2H, NCH2CH2O), 6.97 (d, 1H, 5-H), 7.01 (dd, 1H, 7-H), 7.18 and 7.20 (d, 2H,
30-H, 50-H), 7.56 (d, 1H, 4-H), 7.69 and 7.72 (d, 2H, 20-H, 60-H), 7.75 (d, 1H, 8-H), 7.93 (dd, 1H, 3-
0
0
0
0
H), 8.29 (d, 1H, 1-H) ppm; J1;3 ˆ 1.6 Hz, J2 ,6 ˆ J3 ,5 ˆ 8.5 Hz, J7;5 ˆ 2.5 Hz, J7;8 ˆ 9.2 Hz,
J3;4 ˆ 8.7 Hz, J ˆ 7.1 Hz, JꢁNCH CH O† ˆ 6.2 Hz.
ꢁCH2CH3†
2
2
1-(6-(Ethyl-2-((8-3-(2-(4-¯uorophenyl)-1,3-dioxolan-2-yl)-propyl-4-phenyl-2,4,8-triazaspiro-
[4.5]dec-1-en-1-yl)-oxy)-ethylamino)-2-naphthyl)-1-ethanone (5; C41H47FN4O4) and
1-(6-Ethyl-(2-(8-3-(2-(4-¯uorophenyl)-1,3-dioxolan-2-yl)-propyl-1-oxo-4-phenyl-
2,4,8-triazaspiro[4.5]dec-2-yl)-ethyl)-amino-2-naphthyl)-1-ethanone (6; C41H47Fn4O4)
To a solution of sodium hydroxide (1 g) and tetra-n-butylammonium hydrogensulfate(VI) (50 mg,
0.15 mmol) in water (2 ml), spiperone ketal (8-3-(2-(4-¯uorophenyl)-1,3-dioxolan-2-yl)propyl-1-
phenyl-1,3,8-triazaspiro[4.5]decan-4-one [8], 15 mg, 0.034 mmol) was added and the mixture was
stirred vigorously. After 10 min, a solution of tosylate 4 (12 mg, 0.03 mmol) in toluene (3 ml) was
added, and the reaction mixture was stirred and heated at 90ꢀC for 1 h. After cooling, the reaction
mixture was distributed between water and dichloromethane, and the organic layer was washed with
brine, dried, and evaporated to leave an oily residue. Radial chromatography (1 mm silica, 2%
methanol in dichloromethane) yielded 5 mg (25%) of O-alkyl product 5 and 11 mg (56%) of N-alkyl
product 6.
1
5: HRMS: calcd. for C41H47FN4O4: 678.3581, found: 678.3605; H NMR: ꢁ ˆ 1.45±2.24 (m, 11H,
spiperone CH2, CH2CH3), 2.35±2.84 (m, 6H, spiperone), 2.65 (s, 3H, OCH3), 3.59 (q, 2H,
NCH2CH3), 3.76 in 4.05 (m, 4H, OCH2CH2O), 3.85 (t, 2H, NCH2CH2O), 4.52 (t, 2H, OCH2CH2N),
4.99 (s, 2H, NCH2N), 6.76±6.83 (m, 3H, phenyl, ¯uorophenyl), 6.93 (d, 1H, 5-H), 6.95±7.04
(m, 2H, phenyl, ¯uorophenyl), 7.19 (dd, 1H, 7-H), 7.21±7.26 (m, 2H, phenyl, ¯uorophenyl), 7.39±
7.45 (m, 2H, phenyl, ¯uorophenyl), 7.61 (d, 1H, 4-H), 7.78 (d, 1H, 8-H), 7.93 (dd, 1H, 3-H), 8.30
(d, 1H, 1-H) ppm; J1;3 ˆ 1.5 Hz, J5;7 ˆ 2.4 Hz, J3;4 ˆ 9.5 Hz, J7;8 ˆ 9.2 Hz, J
JꢁNCH CH O† ˆ 6.3 Hz.
ˆ 7.1 Hz,
ꢁCH2CH3†
2
2
1
6: HRMS: calcd. for C41H47FF4O4: 678.3581, found: 678.3603; H NMR: ꢁ ˆ 1.20±1.94 (m, 17H,
spiperone CH2,CH3CH2), 2.66 (s, 3H, COCH3), 3.56 (q, 2H, NCH2CH3), 3.66 and 4.02 (m, 4H,
OCH2CH2O), 3.71±3.81 (m, 4H, NCH2CH2N), 4.68 (s, 2H, NCH2N), 6.82±6.90 (m, 2H, phenyl,
¯uorophenyl), 6.94 (d, 1H, 5-H), 6.98±7.04 (m, 2H, phenyl, ¯uorophenyl), 7.18 (dd, 1H, 7-H), 7.21±
7.26 (m, 3H, phenyl, ¯uorophenyl), 7.39±7.45 (m, 2H, phenyl, ¯uorophenyl), 7.60 (d, 1H, 4-H), 7.78
(d, 1H, 8-H), 7.93 (dd, 1H, 3-H), 8.29 (d, 1H, 1-H) ppm; J1;3 ˆ 1.6 Hz, J3;4 ˆ 9.8 Hz, J5;7 ˆ 2.4 Hz,
J7;8 ˆ 10.4 Hz, J
ˆ 7.1 Hz.
ꢁCH2CH3†

Ï
A. Petric et al.
784
2-(1-(6-Ethyl-(2-(8-3-(2-(4-¯uorophenyl)-1,3-dioxolan-2-yl)-propyl-1-oxo-4-phenyl-2,4,8-
triazaspiro[4.5]dec-2-yl)-ethyl)-amino-2-naphthyl)-ethylidene)-malononitrile (7; C44H47FN6O3)
A solution of 6 (13 mg, 0.018 mmol) and malononitrile (6 mg, 0.09 mmol) in pyridine (3 ml) was
heated at 85ꢀC under argon for 24 h. After removal of pyridine in vacuo at room temperature, the
residue was distributed between brine and dichloromethane, and the organic layer was dried and
evaporated. The product 7 was isolated by radial chromatography (1 mm silica, 2.5% methanol in
dichloromethane; 13.5 mg, 97%).
FAB HRMS: calcd. for C44H48FN6O3 (M‡H): 727.37719, found: 727.3772; 1H NMR: ꢁ ˆ 1.25±
1.93 (m, 17H, spiperone CH2, CH3CH2), 2.70 (s, 3H, C=C-CH3), 3.57 (q, 2H, NCH2CH3), 3.64 and
4,03 (m, 4H, OCH2CH2O), 3,71±3.78 (m, 4H, NCH2CH2N), 4.68 (s, 2H, NCH2N), 6.83±6.88 (m,
2H, phenyl, ¯uorophenyl), 6.94 (d, 1H, 5-H), 6.96±7.04 (m, 2H, phenyl, ¯uorophenyl), 7.18 (dd, 1H,
7-H), 7.21±7.25 (m, 3H, phenyl, ¯uorophenyl), 7.39±7.45 (m, 2H, phenyl, ¯uorophenyl), 7.56 (dd,
1H, 3-H), 7.63 (d, 1H, 4-H), 7.76 (d, 1H, 9-H), 8.00 (d, 1H, 1-H) ppm; J1;3 ˆ 1.9 Hz, J3;4 ˆ 8.8 Hz,
J5;7 ˆ 2.4 Hz, J7;8 ˆ 9.3 Hz, J
ˆ 7.1 Hz.
ꢁCH2CH3†
2-(1-6(Ethyl-(2-8-(4-(4-¯uorophenyl)-4-oxobutyl)-1-oxo-4-phenyl-2,4,8-triazaspiro[4.5]dec-
2-ylethyl)-amino)-2-naphthylethylidene)-malononitrile (8; C42H43FN6O2)
The ketal protective group was removed by stirring compound 7 (13.5 mg, 0.0186 mmol) in methanol
(1 ml) with one drop of concentrated hydrochloric acid for 3 h at room temperature. The reaction
mixture was diluted with dichloromethane and washed with a saturated solution of sodium
bicarbonate. After evaporation in vacuo the residue was puri®ed by radial chromatography (1 mm
silica, 2%) methanol in dichloromethane) to give 10 mg (79%) of 8.
1
FAB MS: calcd. for C42H44FN6O2 (M‡H): 683.35, found: 683; H NMR: ꢁ ˆ 1.21±3.02 (m,
17H, spiperone CH2, CH3), 2.71 (s, 3H, C=C-CH3), 3.56 (q, 2H, NCH2CH3), 3.69 (m, 4H,
NCH2CH2N), 4.67 (s, 2H, NCH2N), 6.79±7.23 (m, 7H, phenyl, ¯uorophenyl), 6.95 (d, 1H, 5-H),
7.19 (dd, 1H, 7-H), 7.56 (dd, 1H, 3-H), 7.65 (d, 1H, 4-H), 7.76 (d, 1H, 8-H), 7.97±8.04 (m, 3H,
¯uorophenyl, 1-H) ppm; J1;3 ˆ 1.9 Hz, J3;4 ˆ 8.8 Hz, J5;7 ˆ 2.5 Hz, J7;8 ˆ 9.1 Hz, J
ˆ 7.1 Hz.
ꢁCH2CH3†
1-(6-Acetyl-2-naphthyl)-4-((4-methylphenyl)-sulfonyloxy)-methylpiperidine (9; C25H27NO4S)
A solution of 3 (59 mg, 0.2 mmol) in pyridine (3 ml) was cooled to ꢂ15ꢀC, and p-toluenesulfonic
anhydride (205 mg, 0.6 mmol) was added with stirring under argon. The reaction mixture was
allowed to warm up slowly to room temperature during 1 h. It was cooled again and distributed
between brine and ether. The organic layer was washed with brine, dried, and evaporated to leave
83 mg (91%) of raw 9. For elemental analysis it was puri®ed by radial chromatography (1 mm silica,
ether). Pure 9 melted at 135±137ꢀC.
1H NMR: ꢁ ˆ 1.39 (dddd, 2H, 3a-H, 5a-H), 1.84 (bd, 2H, 3e-H, 5e-H), 1.93 (m, 1H, 4a-H), 2.46
(s, 3H, PhCH3), 2.67 (s, 3H, COCH3), 2.83 (ddd, 2H, 2a-H, 6a-H), 3.87 (bd, 2H, 2e-H, 6e-H), 3.92
(d, 2H, OCH2), 7.06 (d, 1H, 50-H), 7.27 (dd, 1H, 70-H), 7.36 (d, 2H, 300-H, 500-H (Ts)), 7.65 (d, 1H, 40-
H), 7.79 (d, 1H, 80-H), 7.80 (d, 2H, 200-H, 600-H (Ts)), 7.94 (dd, 1H, 30-H), 8.32 (d, 1H, 10-H) ppm;
J3a;3e ˆ J5a;5e ˆ 12.4 Hz, J2a;3a ˆ J6a;5a ˆ 12.4 Hz, J3a;4a ˆ J5a;4a ˆ 12.4 Hz, J2e;3a ˆ J6e;5a ˆ 4.0 Hz,
0
0
0
0
J2a,2e, J6a;6e ˆ 12.4 Hz, J2a;3e ˆ J6a;5e ˆ 2.4 Hz, J4a;OCH ˆ 6.5 Hz, J1 ,3 ˆ 1.6 Hz, J3 ,4 ˆ 8.7 Hz,
2
0
0
0
0
00 00
00 00
J5 ,7 ˆ 2.4 Hz, J7 ,8 ˆ 9.5 Hz, J2 ,3 ˆ J5 ,6 ˆ 8.1 Hz.
1-(6-(4-((8-3-(2-(4-Fluorophenyl)-1,3-dioxolan-2-yl)-propyl-4-phenyl-2,4,8-triazaspiro[4.5]dec-
1-en-1-yl)-oxy)-methylpiperidino)-2-naphthyl)-1-ethanone (10; C43H49FN4O4) and
1-(6-4-((8-3-(2-(4-¯uorophenyl)-1,3-dioxolan-2-yl)-propyl-1-oxo-4-phenyl-2,4,8-
triazaspiro[4.5]dec-2-yl)-methyl)-piperidino-2-naphthyl)-1-ethanone (11; C43H49FN4O4)
To a solution of sodium hydroxide (1 g) and tetra-n-butylammonium hydrogensulfate(VI) (50 mg,
0.15 mmol) in water (2 ml), spiperone ketal (100 mg, 0.2 mmol) was added, and the mixture was

UV and Vis Fluorescent Probes
785
stirred vigorously. After 10 minutes, a solution of tosylate 9 (98 mg, 0.2 mmol) in toluene (10 ml)
was added, and the reaction mixture was stirred at room temperature for 11 days. It was then
distributed between brine and dichloromethane, and the organic layer was dried and evaporated to
leave 190 mg of an oily residue. Radial chromatography (1 mm silica, dichloromethane followed by
2% methanol in dichloromethane) yielded 27 mg (17%) of O-alkayl 10 and 92 mg (58%) of N-alkyl
product 11.
10: HRMS: calcd. for C43H49FN4O4: 704.3738, found: 704.3760; 1H NMR: ꢁ ˆ 1.46±1.90 (m, 10H,
30a-H, 50a-H, 30e-H, 50e-H, spiperone), 1.88 (m, 1H, 40a-H), 2.15 and 2.38 (b, 4H, spiperone), 2.67 (s,
3H, COCH3), 2.80 (m, 4H, spiperone), 2.95 (m, 2H, 20a-H, 60a-H), 3.75 (m, 2H, OCH2CH2O), 3.87
(m, 2H, 20e-H, 60e-H), 3.92 (m, 2H, OCH2CH2O), 4.19 (d, 2H, OCH2), 4.97 (s, 2H, NCH2N), 6.7±
6.9 (m, 3H, Ph), 7.01 (m, 2H, Ph), 7.11 (d, 1H, 5-H), 7.23 (m, 2H, Ph), 7.32 (dd, 1H, 7-H), 7.41 (m,
2H, Ph), 7.66 (d, 1H, 4-H), 7.81 (d, 1H, 8-H), 7.95 (dd, 1H, 3-H), 8.32 (d, 1H, 1-H) ppm;
0
0
0
0
0
0
0
0
0
J2 a,2 e ˆ J6 a,6 e ˆ 12.4 Hz, J2 a,3 e ˆ J6 a,5 e ˆ 2.6 Hz, J4 a,OCH ˆ 6.1 Hz, J1;3 ˆ 2.1 Hz, J3;4 ˆ 8.8 Hz,
2
J5;7 ˆ 2.1 Hz, J7;8 ˆ 9.1 Hz.
11: HRMS: calcd. for C43H49FN4O4: 704.3738, found: 704.3710; 1H NMR: ꢁ ˆ 1.50 (dddd, 2H, 30a-
H, 50a-H), 1.55±1.70 (m, 4H, spiperone), 1.84 (bd, 2H, 30e-H, 50e-H), 1.92 (m, 2H, spiperone), 1.98
(m, 1H, 40a-H), 2.42 (m, 2H, spiperone), 2.67 (s, 3H, COCH3), 2.69 (m, 2H, spiperone), 2.83 (m, 4H,
spiperone), 2.88 (m, 2H, 20a-H, 60a-H), 3.35 (d, 2H, 40-CH2N), 3.75 (m, 2H, OCH2CH2O), 3.92 (bd,
2H, 20e-H, 60e-H), 4.02 (m, 2H, OCH2CH2O), 4.71 (s, 2H, NCH2N), 6.88 (m, 1H, Ph), 6.91 (m, 2H,
Ph), 7.01 (m, 2H, Ph), 7.08 (bs, 1H, 5-H), 7.27 (m, 3H, 7-H, Ph), 7.43 (m, 2H, Ph), 7.65 (d, 1H, 4-H),
0
0
0
0
7.79 (d, 1H, 8-H), 7.94 (dd, 1H, 3-H), 8.32 (bs, 1H, 1-H) ppm; J3 a,3 e) ˆ J5 a,5 e ˆ 12.4 Hz,
0
0
0
0
0
0
0
0
0
0
0
J2 a,3 a ˆ Hz, J2 a,2e ˆ J6 a,6 e ˆ 12.8 Hz, J2 a,3 e ˆ J6 a,5 e ˆ 2.4 Hz, J4 a,4 -CH N ˆ 7.3 Hz, J1;3 ˆ 1.9 Hz,
2
J3;4 ˆ 8.8 Hz, J5;7 ˆ 2.1 Hz, J7;8 ˆ 9.2 Hz.
2-(1-(6-4-((8-3-(2-(4-Fluorophenyl)-1,3-dioxolan-2-yl)-propyl-1-oxo-4-phenyl-2,4,8-
triazaspiro[4.5]dec-2-yl)-methyl)-piperidino-2-naphthyl)-ethylidene)malononitrile
(12; C46H49FN6O3)
Using the procedure described for the synthesis of 7, compound 11 was transformed into the
malononitrile derivative 12. It was puri®ed by radial chromatography on a 1 mm silica plate using
2% MeOH in CH2Cl2 as the solvent.
FAB HRMS: calcd. for C46H50FN6O3 (M‡H): 753.3928, found: 753.3940; 1H NMR: ꢁ ˆ 1.60±
2.1 (m, 11H, spiperone, 30a-H, 30e-H, 40a-H, 50a-H, 50e-H), 2.40 (m, 2H, spiperone), 2.71 (s, 3H,
C=CCH3), 2.60±2.80 (m, 6H, spiperone), 2.91 (m, 2H, 20a-H, 60a-H), 3.37 (d, 2H, 40-CH2N), 3.75
(m, 2H, OCH2CH2O), 3.94 (bd, 2H, 20e-H, 60e-H), 4.02 (m, 2H, OCH2CH2O), 4.72 (s, 2H, NCH2N),
6.85±6.95 (m, 3H, Ph), 7.01 (m, 2H, ¯uorophenyl), 7.07 (d, 1H, 5-H), 7.31 (m, 3H, 7-H, Ph), 7.41
(m, 2H, ¯uorophenyl), 7.56 (dd, 1H, 3-H), 7.69 (d, 1H, 4-H), 7.77 (d, 1H, 8-H), 8.01 (d, 1H, 1-H)
0
0
0
0
0
0
0
0
0
ppm; J2 a,3 a ˆ J5 a,6a ˆ 12.8 Hz, J2 a,2 e ˆ J6 a,6 e ˆ 12.8 Hz, J4 a,4 -CH N ˆ 7.6 Hz, J1;3 ˆ 1.8 Hz,
2
0
0
0
0
J3;4 ˆ 8.6 Hz, J5;7 ˆ 2.2 Hz, J7;8 ˆ 9.4 Hz, J2 a,3 e ˆ J5 e,6 a ˆ 1.8 Hz, JH;F ˆ 8.7 and 6.2 Hz.
2-(1-6-(4-(8-(4(4-Fluorophenyl)-4-oxobutyl)-1-oxo-4-phenyl-2,4,8-triazaspiro[4,5]dec-2-ylmethyl)-
piperidino)-2-naphthylethylidene)-malononitrile (13; C44H45FN6O2)
The ketal protective group was removed from 12 as described for 8 to give 13 in quantitative yield.
FAB HRMS: calcd. for C44H46FN6O2 (M‡H): 709.3666, found: 709.3689; 1H NMR: ꢁ ˆ 1.60±
2.1 (m, 11H, spiperone, 30a-H, 30e-H, 40a-H, 50a-H, 50e-H), 2.5±2.71 (m, 4H, spiperone), 2.73 (s, 3H,
C=C-CH3), 2.8±3.1 (m, 6H, spiperone, 20a-H, 60a-H), 3.38 (d, 2H, 40-CH2N), 3.96 (bd, 2H, 20e-H,
60e-H), 4.74 (s, 2H, NCH2N), 6.91 (m, 3H, phenyl), 7.1 (d, 1H, 5-H), 7.15 (m, 2H, ¯uorophenyl),

Ï
A. Petric et al.: UV and Vis Fluorescent Probes
786
7.24±7.30 (m, 2H, Ph), 7.34 (dd, 1H, 7-H), 7.58 (dd, 1H, 3-H), 7.72 (d, 1H, 4-H), 7.79 (d, 1H, 8-H),
8.01±8.08 (m, 3H, ¯uorophenyl, 1-H) ppm; J1;3 ˆ 2.0 Hz, J3;4 ˆ 8.6 Hz, J5;7 ˆ 2.4 Hz, J7;8 ˆ 9.2 Hz,
0
0
0
0
0
0
0
0
0
0
0
0
0
0
J4 a,4 -CH N ˆ 7.4 Hz, J2 a,2 e ˆ J6 a,6 e ˆ 13.0 Hz, J2 a,3 a ˆ J5 a,6 a ˆ 12.5 Hz, J2 a,3 e ˆ J5 e,6 a ˆ 1.9 Hz,
2
JH,F ˆ 8.7 and 6.2 Hz.
Acknowledgements
This work was supported by the US-Slovene Science and Technology Joint Fund in cooperation with
the US Department of Energy and the Ministry of Science and Technology of the Republic of
Slovenia (Project No. US-SLO 95/2-02), in part by the US Department of Energy (Grant DE-
FC0387-ER60615), and in part by the Ministry of Science and Technology of the Republic of
Slovenia.
References
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[6] Petric A, Barrio JR (1994) J Heterocyclic Chem 31: 545
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[9] Arsenijevic L, Arsenijevic V, Horeau A, Jacques J (1988) Org Synth Coll Vol 6: 34
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ꢁ
Received January 16, 1998. Accepted (revised) April 10, 1998