α-substituted 1-aryl-3-dimethylaminopropanone hydrochlorides: Potent cytotoxins towards human WiDr colon cancer cells

Article abstract of DOI:10.1248/cpb.55.511

A series of 1-aryl-2-dimethylaminomethyl-2-propenone hydrochlorides 1 were prepared which possessed IC₅₀ values of less than 10 μM when examined towards human WiDr colon cancer cells. The related 1-aryl-2- dimethylaminomethyl-3-hydroxypropanone

Full text of DOI:10.1248/cpb.55.511

April 2007
Chem. Pharm. Bull. 55(4) 511—515 (2007)
511
a
-Substituted 1-Aryl-3-dimethylaminopropanone Hydrochlorides: Potent
Cytotoxins towards Human WiDr Colon Cancer Cells
Hari Narayan PATI,a Umashankar DAS,a Irving Javier RAMIREZ-EROSA,b Donna Mae DUNLOP,b
Robert Allan HICKIE,b and Jonathan Richard DIMMOCK*,a
a College of Pharmacy and Nutrition, University of Saskatchewan; 110 Science Place, Saskatoon, Saskatchewan S7N 5C9,
Canada: and bDepartment of Pharmacology, College of Medicine; 107 Wiggins Road, Saskatoon, Saskatchewan S7N 5E5,
Canada. Received May 24, 2006; accepted January 29, 2007
A series of 1-aryl-2-dimethylaminomethyl-2-propenone hydrochlorides 1 were prepared which possessed
IC50 values of less than 10 mM when examined towards human WiDr colon cancer cells. The related 1-aryl-2-di-
methylaminomethyl-3-hydroxypropanone hydrochlorides 2, formed by hydration of the analogs in series 1, also
had IC50 values in the low micromolar range. On the other hand, conversion of 2-dimethylaminomethyl-1-(4-ni-
trophenyl)-2-propenone hydrochloride 1c into the corresponding 2-mercaptoethanol of adduct 3c led to a 37-fold
reduction in potency. Two thirds of the compounds prepared in this study were more potent than a reference
drug cisplatin while one third of these molecules displayed greater cytotoxicity to the WiDr cells than human
CRL-2522 fibroblasts. A stability study of the 4-nitrophenyl analog in each of the series 1—3 in deuterium oxide
was undertaken. In the case of 1c, replacement of the dimethylamino hydrochloride group by a hydroxy function
was noted while in series 2, the loss of both water and dimethylamine hydrochloride gave rise to a mixture of two
enones. The mercaptoethanol adduct 3c underwent deamination. The data obtained provide guidelines for am-
plifying the project in the future.
Key words cytotoxicity; 1-aryl-3-dimethylaminopropanone; stability study; colon cancer
A number of different series of a,b-unsaturated ketones when the compound was formulated in niosomes. The con-
have been synthesized in our laboratories as candidate anti- clusions from this study were that the 1-aryl-2-dimethyl-
neoplastics.1,2) These compounds were designed as thiol aminomethyl-2-propenone hydrochlorides are promising lead
alkylators. Conversion of various conjugated arylidene ke- compounds and their gradual release in vivo improved the
tones into the corresponding Mannich bases led to com- bioactivity.
pounds with substantially increased rates of reaction with a
A review of the literature revealed that a number of inves-
model thiol which was attributed to greater stabilization of tigations have been undertaken with a view to determining
the reaction intermediate as well as solvation effects.3) Sev- the modes of action of 1-aryl-2-dimethylaminomethyl-2-
eral studies revealed that Mannich bases of enones reacted propenone hydrochlorides and adducts derived from these
with thiols but not with amino and hydroxy groups.4,5) Hence compounds. A previous study from our laboratory revealed
the genotoxic properties of a number of anticancer drugs cur- that 1a is a potent inhibitor of respiration in mitochondria
rently in use6) may be absent with these compounds. In addi- isolated from mouse liver cells having an ID50 value (the con-
tion, since Mannich bases of conjugated arylidene ketones centration required to inhibit respiration by 50%) of
are structurally divergent from current anticancer drugs, the 1.14 mM.9) The antimitochondrial properties of 1a and related
problem of their being cross-resistant to established medica- compounds were attributed to the presence of an enone
tion may be absent. The disclosure that several drug-resistant group and a basic centre located two carbon atoms from the
cell lines were free from cross-resistance to a number of carbonyl function, while hydrophobicity also influenced po-
Mannich bases of conjugated arylidene ketones7) supports tencies. Other investigators observed that 1a, b, e and related
this contention.
compounds inhibited tubulin polymerization.10,11) The shape
Earlier investigations from these laboratories described the of platelets is maintained by its microtubular cytoskeleton12)
noteworthy antineoplastic properties of the 1-aryl-2-dimethyl- and the secretion of lipoproteins into the extracellular space
aminomethyl-2-propenone hydrochlories.8) Thus the IC50 val- is influenced by the microtubular system.13) Compounds
ues of 1a, e towards a panel of human tumor cell lines are 1a, b, e and related analogs inhibited human ADP-induced
6.92 and 4.07 mM, respectively. In addition, the weights of platelet aggregation.10) A preliminary report revealed that 1a
various human tumor xenografts passaged in athymic mice and two analogs decreased the serum concentrations of
were reduced by several of these compounds, e.g., 1a, e triglycerides and cholesterol in rats treated with Triton WR
caused a reduction in the growth of the COLO 205 colon 1339 which induces hyperlipidemia in these animals.14)
A
cancer by 40 and 45%, respectively, while the weight of the subsequent study with 1a, b, e and analogs also reported this
PC-3 prostate tumor was lowered by 61% by 1e. A dose of phenomena as well as revealing an increase in phospholipids.
4 mg/kg of 1a increased the life span of mice with Ehrlich These studies confirm that an important site of action of
ascites carcinoma by 282% which was increased to 322% these compounds is the microtubules. In addition, 1a selec-
when the compound was formulated in niosomes. All mice tively inhibited a protein tyrosine kinase (PTK), namely epi-
inoculated with B16F1 melanoma were dead after 60 d. How- dermal growth factor receptor (EGFR) in contrast to having
ever the percentage survivors of animals receiving 4 mg/kg minimal or no effects on other tyrosine or serine/threonine
of 1a 60 and 230 d after administration of the Mannich base kinases.15) An analog of 1a in which a 4-benzyloxy group
were 30 and 10; these figures were increased to 40 and 20 was placed in the aryl ring was reacted with various thiols to
∗ To whom correspondence should be addressed. e-mail: jr.dimmock@usask.ca
© 2007 Pharmaceutical Society of Japan

512
Vol. 55, No. 4
Chart 1. Synthetic Chemical Pathway for Preparing Compounds in Series 1—3
The reagents used were as follows: a. 2HCHO, NH(CH3)2·HCl, b. H2O/pHꢂ8—9, c. HSCH2CH2OH.
give the corresponding adducts which also showed a selec- ding aminoalcohols 2a—e. 2-Mercaptoethanol condensed
tive inhibition of the activity of EGFR PTK. Evaluation of 1a with 1c to give the thiol adduct 3c.
and several thiols adducts against murine BALB/MK epider-
Representative compounds in each series, namely 1c, 2c
mal keratinocytes, whose proliferation depends on EGF,16) re- and 3c, were incubated in deuterium oxide at 37 °C for 48 h
vealed that a number of compounds had IC50 values in the which were the temperature and time of the cytotoxicity ex-
low micromolar range.15) Furthermore, flow cytometric periment vide infra. The products formed were identified by
analysis of 1a revealed that cell cycle transit in murine P388 1H-NMR spectroscopy and are indicated in Chart 2. Since
leukemia cells was completely blocked and there was no evi- both 1c and 2c gave rise to 2-hydroxymethyl-1-(4-nitro-
dence of any phase-dependent effects.17) Thus in addition to phenyl)-2-propenone 4, the compound was synthesized in
specific sites of action, namely mitochondria, microtubules order that its cytotoxicity could be determined.
and at least one PKT, 1a (and presumably its analogs in se-
Cytotoxicity The compounds in series 1—4 were evalu-
ries 1 and 2) has additional sites of action such as different ated against both human WiDr colon cancer cells and human
phases of the cell cycle. Since cancer cells are dysregulated CRL-2522 foreskin fibroblasts. These data, along with the re-
causing a myriad of aberrant biochemical reactions, the value sults from the assays using a reference drug namely cisplatin,
of multifunctional compounds is clear. In fact, the value of are presented in Table 1.
the marked pleiotropy of candidate cytotoxins has recently
been articulated.18)
Discussion
The objectives of the present study were to prepare a num-
The biodata presented in Table 1 reveal that the com-
ber of prototypic molecules in order to formulate guidelines pounds in series 1 and 2 are potent cytotoxics. A preliminary
as to how the project should be amplified. The specific series observation indicated that 3c was virtually devoid of potency
of compounds 1—3 are presented in Chart 1 and the design since a concentration of 50 mM of this compound caused only
of these molecules was based on the following considera- 1.9% and 11.1% mortalities of the WiDr and CRL-2522
tions. In regard to the aryl substituents, groups with widely cells, respectively. Hence further analogs in series 3 were not
differing physicochemical properties were chosen. The Ham- prepared.
mett sigma (s) and Hansch pi (p) values of these sub-
The potencies of the compounds in series 1—3 were com-
stituents are a measure of their electronic and hydrophobic pared with that of the established anticancer drug cisplatin
properties, respectively. Hence groups with positive (ꢀ) and whose mode of action resembles that of alkylating agents.21)
negative (ꢁ) s and p values were chosen, namely chloro With the exception of the 4-nitro analogues 1c and 2c, the
(ꢀ, ꢀ), nitro (ꢀ, ꢁ), methyl (ꢁ, ꢀ) and methoxy (ꢁ, ꢁ) compounds in series 1 and 2 are in the range of 1.5—3.7
which are found in b—e, respectively. In addition, the molar times the potency of cisplatin when examined against human
refractivity (MR) figures for the hydro, chloro, nitro, methyl WiDr colon cancer cells. The highest potencies were dis-
and methoxy groups are 1.03, 6.03, 7.36, 5.65 and 7.87, re- played by 1d, 1e and 2d. In order to ascertain whether
spectively.19) Since a gradual release of 1a improved bioac- greater toxicity would be demonstrated towards tumorous
tivity vide supra, the aminoalcohols 2a—e were suggested cells than normal tissues, the compounds were also examined
which may undergo dehydration to liberate the correspon- against human CRL-2522 foreskin fibroblasts. The data gen-
ding enones 1a—e. The conjugated unsaturated aldehyde erated indicate that 1a, d and 2a, d exerted a statistically sig-
acrolein, which is a metabolite of cyclophosphamide, gives nificant chemoselectivity for the malignant cells. Thus in
rise to cystitis which may be ameliorated by the coadminis- particular 1d and 2d are clearly lead molecules due to the po-
tration of a thiol.20) In order to examine the possibility that tencies displayed towards WiDr cells coupled to their tumour
cytotoxicity would be retained and a thiol liberated, the for- selectivity.
mation of the thiol adduct 3c obtained from 1c was sug-
With a view to developing guidelines for the amplification
gested.
of series 1 and 2, the cytotoxicity observed was evaluated
Chemistry Reaction of various 1-arylethanones with di- with reference to both the nature of the aryl substituents and
methylamine hydrochloride and excess of paraformaldehyde the presence of the methylene (ꢂCH2) group in series 1 vis-
led to the formation of the Mannich bases 1a—e. These com- à-vis the hydroxymethyl function in series 2. Variation in cy-
pounds reacted readily with water producing the correspon- totoxic potencies among the analogs in either series 1 or 2

April 2007
513
Chart 2. Stability of 1c, 2c and 3c after Incubation in Deuterium Oxide at 37 °C for 48 h.
Table 1. Evaluation of the Compounds in Series 1—4 versus WiDr and
CRL-2522 Cells
may be influenced by the electronic, hydrophobic and steric
properties of the aryl substituents. Hence linear and semilog-
arithmic plots were made between the s, p and MR values
of the aryl groups with the IC50 values generated in the WiDr
and CRL-2522 assays. In series 1, a negative correlation was
found between the s values and potencies in the WiDr
screen (pꢃ0.05) indicating that cytotoxicity is favoured by
electron-donating groups. This observation is counterintu-
itive as one would anticipate that increasing the electron den-
sity on the terminal olefinic carbon atom in series 1 would
lead to diminished electrophilicity for cellular thiols and
hence reduced potencies. For series 2, a similar negative cor-
relation (pꢃ0.05) was noted in both the WiDr and CRL-2522
screens. No other correlations (pꢃ0.05) were noted.
In order to determine whether a methylene group as in se-
ries 1 or a hydroxymethyl substituent present in 2a—e en-
hanced cytotoxicity, the potencies of the analogs in series 1
and 2 which had the same aryl substituent were compared. In
the WiDr assay, 1c—e were more potent than 2c—e while
1a, b, 2a, b had statistically indistinguishable IC50 values. On
the other hand, when higher IC50 values are desired in the
LC50 (mM)
Compound
S.I.a)
WiDr
CRL-2522
1a
1b
1c
1d
1e
2a
2b
2c
2d
4.9ꢄ1.0
4.1ꢄ0.6
8.4ꢄ0.5
2.0ꢄ0.1
2.0ꢄ0.1
3.7ꢄ0.2
4.5ꢄ0.3
12.8ꢄ2.4
2.5ꢄ0.3
4.0ꢄ0.3
311ꢄ4.2
13.0ꢄ1.2
7.4ꢄ1.7
7.2ꢄ0.5
4.0ꢄ0.4
8.6ꢄ0.1
2.9ꢄ0.2
2.5ꢄ0.6
4.1ꢄ0.1
4.1ꢄ0.3
12.5ꢄ0.4
3.3ꢄ0.3
1.4ꢄ0.2
218ꢄ3.4
13.0ꢄ1.6
14.6ꢄ3.8
1.47*
0.91
1.02
1.45*
1.25
1.11*
0.91
0.98
1.32*
0.35
0.70
1.00
2e
3c
4
Cisplatin
1.98*
a) The letters S.I. refer to the selectivity index, i.e., the ratio of the IC50 values be-
tween the CRL-2522 and WiDr cells. Figures marked with an asterisk indicate a statis-
tically significant greater toxicity of the compound towards WiDr cells compared to
CRL-2522 fibroblasts.
CRL-2522 assays, 1a, e had lower potencies than 2a, e while was undertaken for the following reasons, namely to (i) gain
1c was more toxic than 2c and 1b, d, 2b, d were equipotent. an insight into the possible way that the compounds behave
Thus from an assessment of the biodata for series 1 and 2, in vitro, (ii) ascertain the likelihood of whether the com-
the following guidelines for expanding this study may be for- pounds in series 2 and 3 are prodrugs of the enones 1, and
mulated. First, in terms of increasing the potencies towards (iii) determine the cause of the variation in cytotoxicity be-
WiDr cells, aryl substituents with lower s values than the 4- tween series 1 and 2 on one hand and the absence of marked
methoxy substituent (spꢂꢁ0.27) should be employed. The potency of 3c. Accordingly, the 1H-NMR spectra of solutions
biodata generated will enable a more thorough evaluation of of 1c, 2c and 3c in deuterium oxide were determined after
whether a corresponding increase in cytotoxicity to CRL- 48 h incubation and the results are portrayed in Chart 2. The
2522 cells takes place or if greater Selectivity Index values principal product obtained from the Mannich base 1c is the
will emerge. Second, in terms of potencies to WiDr cells, the unsaturated alcohol 4 which presumably arose via the inter-
development of analogs of the enones 1 rather than the corre- mediate 2c. In addition, 1c was present which could have
sponding hydroxymethyl series 2 is clearly indicated. Also been formed by dehydration of 2c or be unreacted material.
the data for the CRL-2522 cells suggests that higher IC50 val- The aminoalcohol 2c produced both the dehydrated and
ues are found with the compounds in series 1. In summary, deaminated products, namely 1c and 4, respectively. However
therefore, expansion of series 1 by inserting strongly elec- 3c underwent only deamination and no dethiolation product
tron-donating groups into the aryl ring is indicated.
was observed. The following conclusions were drawn from
The stability of representative compounds in series 1—3 this study. First, the compounds in series 1 and 2 likely give
under simulated conditions of the cytotoxicity assays, viz. in- rise to a mixture of the enones 1 and aminoalcohols 4. Sec-
cubation of solutions of the compounds at 37 °C for 48 h, ond, series 2 but not 3 appear to be prodrugs of the Mannich

514
Vol. 55, No. 4
with sodium carbonate solution (10%) to pH 8—9 and extracted with chlo-
roform (3ꢅ100 ml). The combined chloroform extracts were dried over
sodium sulfate and removal of the solvent in vacuo gave a viscous oil which
was purified by column chromatography using an eluting solvent of chloro-
form : methanol (95 : 5). The free base was dissolved in diethyl ether
(100 ml) and after acidification with dry hydrogen chloride, a colorless solid
was obtained which was collected and recrystallized from ethanol to give the
aminoalcohols 2a—e.
bases 1. Third, the lack of cytotoxic potency in series 3 may
be explained by the absence of dethiolation which prevented
the formation of the cytotoxic species 1. In order to deter-
mine whether 4 contributed to the cytotoxicity observed in
series 1 and 2, this compound was examined in the WiDr and
CRL-2522 assays. The IC50 figures of 4 portrayed in Table 1
reveal that this compound contributes significantly to the cy-
totoxicity of 1c and 2c.
1
Compound 2a: Yield 60%; mp 107 °C; H-NMR (D2O) d: 2.84 (s, 3H),
3.39 (d, 1H, Jꢂ9.64 Hz), 3.88 (m, 3H), 4.47 (m, 1H), 7.51 (m, 2H), 7.66 (m,
1H), 7.94 (d, 2H, Jꢂ7.33 Hz). Found
C 51.89; H 6.43; N 5.01%.
Conclusions
C12H18ClNO2·2H2O requires C 51.59; H 6.44; N 5.01%.
1
Compound 2b: Yield 62%; mp 127 °C; H-NMR (D2O) d: 2.84 (s, 3H),
2.91 (s, 3H), 3.40 (d, 1H, Jꢂ9.65 Hz), 3.87 (m, 3H), 4.45 (m, 1H), 7.58 (d,
2H, Jꢂ8.50 Hz), 7.92 (d, 2H, Jꢂ8.60 Hz). Found C 48.77; H 5.51; N 4.46%.
C12H17Cl2NO2·H2O requires C 48.66; H 5.78; N 4.75%.
This study has demonstrated that the compounds in series
1 and 2 are potent cytotoxins most of which display signifi-
cantly greater antineoplastic potencies than cisplatin. In par-
ticular, 1d and 2d are clearly lead molecules having low IC50
1
Compound 2c: Yield 53%; mp 175 °C; H-NMR (D2O) d: 2.83 (s, 6H),
values when assayed against WiDr colon cancer cells and 3.38 (m, 1H), 3.85—3.89 (m, 3H), 4.46 (m, 3H), 8.28 (d, 2H, Jꢂ9.15 Hz),
8.38 (d, 2H, Jꢂ8.80 Hz). Found
C 46.44; H 5.66; N 8.59%.
also they demonstrated a preferential cytotoxicity to these
cells compared to normal fibroblasts. The stability studies re-
vealed that the compounds in series 2 liberate the analogs in
series 1. It is possible that molecular modification of the hy-
droxy function in series 2 may control the rate of release of
the analogs in series 1 and the ratio of the released Mannich
bases 1 and corresponding allyl alcohol, e.g., 4, may vary
which could affect potencies and possibly give rise to in-
creased selective toxicity for the tumorous cells rather than
the fibroblasts.
C12H17ClN2O4·1.25H2O requires C 46.36; H 5.47; N 9.01%.
1
Compound 2d: Yield 68%; mp 114 °C; H-NMR (D2O) d: 2.33 (s, 3H),
2.84 (s, 3H), 2.90 (s, 3H), 3.38 (d, 1H, Jꢂ13.30 Hz), 3.87 (m, 3H), 4.44 (m,
1H), 7.32 (d, 2H, Jꢂ7.94 Hz), 7.85 (d, 2H, Jꢂ7.62 Hz). Found C 58.56;
H 7.41; N 4.80%. C13H20ClNO2·0.5H2O requires C 58.53; H 7.55;
N 5.25%.
Compound 2e: Yield 72%; mp 138 °C; 1H-NMR (D2O) d: 2.81 (s,
3H), 2.88 (s, 3H), 3.36 (d, 1H, Jꢂ13.30 Hz), 3.87 (m, 6H), 4.43 (m, 1H),
7.03 (d, 2H, Jꢂ8.73 Hz), 7.96 (d, 2H, Jꢂ8.80 Hz). Found C 53.16; H 6.43;
N 4.94%. C13H20ClNO3·H2O requires C 53.58; H 6.87; N 4.80%.
Synthesis of 2-Dimethylaminomethyl-3-(hydroxyethylthio)-1-(4-nitro-
phenyl)-1-propanone Hydrochloride 3c A mixture of 1c (0.0035 mol), 2-
mercaptoethanol (0.0052 mol) and dry chloroform (20 ml) was stirred at
20—22 °C for 12 h. The solvent was removed in vacuo and the residue was
recrystallized from ethanol to give 3c as a colorless solid. Yield 57%; mp
135 °C; 1H-NMR (D2O) d: 2.56 (m, 2H), 2.83—2.87 (m, 7H), 3.04 (m, 1H),
3.50—3.53 (m, 2H), 3.82 (m, 1H), 4.33 (m, 1H), 8.16 (d, 2H, Jꢂ7.00 Hz),
8.34 (d, 2H, Jꢂ7.45 Hz). Found C 48.19; H 6.14; N 7.78% C14H21ClN2O4S
requires C 48.20; H 6.07; N 8.03%.
Experimental
Chemistry Melting points were determined in Celsius degrees using a
Gallenkamp 889339 apparatus and are uncorrected. 1H- and 13C-NMR spec-
tra (500 MHz) were determined in deuterated solvents using a Bruker AM
500 FT spectrophotometer. The letters s, d, t and m indicate singlet, doublet,
triplet and multiplet, respectively.
Elementary analyses (C, H, N) were undertaken on 1b—e, 2a—e and 3c
by the Microanalytical Laboratory, Department of Chemistry, University of
Alberta and by Mr. K. Thoms, Department of Chemistry, University of
Saskatchewan. Mass spectrometry was performed using a VG70SE mass
spectrometer. Column chromatography was undertaken using silica gel 60
(70—230 mesh).
Synthesis of 2-Hydroxymethyl-1-(4-nitrophenyl)-prop-2-en-1-one
4
A solution of 1c (1 g) in demineralized water (30 ml) was incubated at 37 °C
for 48 h and extracted with ethyl acetate (2ꢅ50 ml). The combined organic
extracts were washed with water (2ꢅ50 ml) and dried over sodium sulfate.
Evaporation of the solvent in vacuo gave a viscous oil which was purified by
column chromatography using an eluting solvent of hexane : ethyl acetate
(4 : 1) to give 4 as an oil.
Synthesis of 1-Aryl-2-dimethylaminomethyl-prop-2-en-1-one Hy-
drochlorides, 1a—e. General Procedure A mixture of the appropriate
acetophenone (0.41 mol), paraformaldehyde (0.82 mol) and dimethylamine
hydrochloride (0.82 mol) in acetic acid (750 ml) was heated under reflux for
12 h. Acetic acid was removed in vacuo and the residue was dissolved in
acetone (500 ml). After 8 h, the precipitate was collected, dried and purified
by column chromatography using chloroform : methanol (97 : 3) as the elut-
ing solvent to give the desired products 1a—e.
1
Compound 4: Yield 35%; H-NMR d: 4.56 (s, 2H), 5.86 (s, 1H), 6.31 (s,
1H), 7.90 (d, 2H, Jꢂ8.6 Hz), 8.33 (d, 2H, Jꢂ8.7 Hz)l; 13C-NMR d: 62.75,
124.05, 129.38, 130.56, 143.01, 146.69, 150.25, 196.26; EI-MS (m/z) 206
(MꢁH), 190 (MꢁOH).
Stability Study of Representative Compounds Compounds 1c, 2c and
3c were dissolved in deuterium oxide to form 10 mM solutions and the H-
1
Compound 1a: Yield 78%; mp 157 °C (lit.17) mp 156—158 °C); 1H-NMR
(D2O) d: 2.87 (s, 6H), 4.06 (s, 2H), 6.35 (s, 1H), 6.60 (s, 1H), 7.51 (t, 2H),
7.64 (t, 1H), 7.71 (d, 2H, Jꢂ7.10 Hz).
NMR spectra were recorded immediately on dissolution and after 48 h incu-
bation at 37 °C. The products formed from 1c and 2c were identified by 1H-
NMR spectroscopy and the relative concentrations of the compounds present
in solution were obtained by comparing the intensities of the olefinic pro-
tons.
1
Compound 1b: Yield 72%; mp 160 °C; H-NMR (D2O) d: 2.83 (s, 6H),
4.03 (s, 2H), 6.33 (s, 1H), 6.57 (s, 1H), 7.49 (d, 2H, Jꢂ8.30 Hz), 7.66 (d,
2H, Jꢂ8.25 Hz). Found C 54.64; H 5.96; N 5.15%. C12H15Cl2NO·0.25H2O
requires C 54.45; H 5.90; N 5.29%.
The aminoalcohol 3c was converted into 2-(2-hydroxyethylthiomethyl)-1-
(4-nitrophenyl)-prop-2-en-1-one 5 which was identified by 1H-NMR spec-
troscopy and mass spectrometry.
1
Compound 1c: Yield 68%; mp 170 °C; H-NMR (D2O) d: 2.85 (s, 6H),
Compound 5: 1H-NMR d: 2.73 (t, 2H), 3.62 (s, 2H), 3.74 (t, 2H), 5.86 (s,
1H), 6.25 (s, 1H), 7.94 (d, 2H, Jꢂ8.52 Hz), 8.38 (d, 2H, Jꢂ8.53 Hz). CI-MS
(m/z) 268.05 (MꢀH)ꢀ, 285 (MꢀHꢀNa)ꢀ.
4.06 (s, 2H), 6.38 (s, 1H), 6.67 (s, 1H), 7.84 (d, 2H, Jꢂ8.70 Hz), 8.27 (d,
2H, Jꢂ8.95 Hz). Found C 52.77; H 5.48; N 9.95%. C12H15ClN2O3·0.5H2O
requires C 52.32; H 5.45; N 10.17%.
1
Cytotoxicity Assay The cytotoxic potencies of the compounds prepared
in this study were assessed using a standardized protocol.22) In brief, the
assay employed WiDr (ATCC # CCL 218) human colon cancer cells and
CRL-2522 human BJ foreskin fibroblasts. Compounds were evaluated using
concentrations of 1.56, 3.13, 6.25, 12.5, 25 and 50 mM. In the case of 3e, ad-
ditional concentrations of 100, 200 and 400 mM were employed. After 48 h
incubation in a humidified 5% carbon dioxide atmosphere at 37 °C, cell via-
bility was determined using the MTT tetrazolium salt assay.23) The IC50
value is the concentration of the compound to kill 50% of the cells and was
determined from dose–response curves. The analyses were undertaken in
triplicate at each concentration.
Compound 1d: Yields 72%; mp 158 °C; H-NMR (D2O) d: 2.46 (s, 3H),
2.80 (s, 6H), 4.02 (s, 2H), 6.30 (s, 1H), 6.53 (s, 1H), 7.31 (d, 2H,
Jꢂ7.78 Hz), 7.65 (d, 2H, Jꢂ7.97 Hz). Found C 63.95; H 7.43; N 5.75%.
C13H18ClNO·0.5H2O requires C 63.94; H 7.49; N 5.32%.
Compound 1e: Yield 75%; mp 152 °C (lit.17) mp 151—152 °C); H-NMR
1
(D2O) d: 2.83 (s, 6H), 3.85 (s, 3H), 4.01 (s, 2H), 6.26 (s, 1H), 6.48 (s, 1H),
7.01 (d, 2H, Jꢂ8.80 Hz), 7.57 (d, 2H, Jꢂ8.75 Hz). Found C 60.43; H 6.81;
N 5.25%. C13H18ClNO2·0.25H2O requires C 59.99; H 7.16; N 5.38%.
Synthesis of 1-Aryl-2-dimethylaminomethyl-3-hydroxy-1-propanone
Hydrochlorides 2a—e. General Procedure The crude Mannich base in
series 1 (20 g) was dissolved in water (60 ml) and the solution was basified

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Acknowledgements The authors thank the Canadian Institutes of
M., Mallevais M. L., Delacourte A., Dubreuil L., Devos J., Romond
Health for a grant to J. R. Dimmock (MOP-53171). I. J. Ramirez-Erosa was
C., Arzneim.-Forsch., 36, 20—24 (1986).
supported by the Agriculture Development Fund of the Government of 11) Mallevais M. L., Delacourte A., Lesieur I., Lesieur D., Cazin M.,
Saskatchewan and the Maunders McNeil Foundation Inc. which are grate-
fully acknowledged.
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