Synthesis and characterization of chroman-containing compounds and their preliminary assessment of cytotoxicity toward two human cancer cell lines

Article abstract of DOI:10.1002/hc.20621

A series of chroman derivatives were synthesized by employing o-methyl phenol as a precursor. These compounds were fully characterized using IR, NMR spectroscopic techniques, and elemental analysis. Mechanisms for the formation of the chroman moiety of these compounds were also proposed. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to estimate their cytotoxicity toward two cancer cell lines: human ovarian cancer (A2780) and human cervical cancer (Hela).

Full text of DOI:10.1002/hc.20621

Heteroatom Chemistry
Volume 21, Number 6, 2010
Synthesis and Characterization of
Chroman-Containing Compounds and
Their Preliminary Assessment of Cytotoxicity
Toward Two Human Cancer Cell Lines
Ying Tang,1 Jie Wei,2 Wei Zhong,1 and Xiaoming Liu1
1Department of Chemistry/Institute for Advanced Study, Nanchang University,
Nanchang 330031, People’s Republic of China
2Department of Physiology, Medical College, Nanchang University, Nanchang 330006,
People’s Republic of China
Received 3 April 2010; revised 5 June 2010
erocyclic compounds are widely found in many do-
ABSTRACT: A series of chroman derivatives were
mestic products, for instance, medicines, pesticides,
synthesized by employing o-methyl phenol as a pre-
and herbicides.
cursor. These compounds were fully characterized
Compounds containing chroman and chromene
using IR, NMR spectroscopic techniques, and el-
moieties represent a large category of heterocyclic
emental analysis. Mechanisms for the formation
compounds, for example, benzopyran chalcone,
of the chroman moiety of these compounds were
coumarin, flavone, and vitamin E (VE) (Fig. 1).
also proposed. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-
These compounds draw scientists’ attention due to
diphenyltetrazolium bromide) assay was used to esti-
their antitumor, antibacterial, and analgesic effects
mate their cytotoxicity toward two cancer cell lines:
[1–2]. In 1960s, scientists isolated a number of ben-
human ovarian cancer (A2780) and human cervi-
zopyran chalcone compounds from certain plants,
ꢀ
C
cal cancer (Hela).
2010 Wiley Periodicals, Inc. Het-
investigated their physiological activities, and ulti-
mately achieved their total synthesis [3]. Synthesized
flavone and flavonoid compounds are used to treat
coronary heart disease [4]. A large number of syn-
thesized coumarin compounds have been reported
and have been proven to be efficacious anticoag-
ulants [5]. A chroman moiety is an indispensable
component of VE, which is an important trace nu-
trient for human beings due to its antioxidant prop-
erty [6]. In the past decades, there have been many
reports concerning the modification of VE to pre-
pare its analogues [7]. One particular example is
α-tocopheryl succinate (α-TOS), which can selec-
tively kill tumor cells via destabilization the function
of mitochondria with low toxicity to normal cells
[8,9].
eroatom Chem 21:423–429, 2010; View this article online
at wileyonlinelibrary.com. DOI 10.1002/hc.20621
INTRODUCTION
Heterocyclic compounds exist widely in nature, for
example, nucleic acids, vitamins, antibiotics, hor-
mones, pigments, and alkaloids. These molecules
play various physiological roles in biological sys-
tems. It is a great inspiration from nature to explore
the applications of heterocycles. A typical example is
total synthesis of natural products and then investi-
gation into their applications. Indeed, synthetic het-
Correspondence to: Xiaoming Liu; e-mail: xiaoming.liu@
Herein, we describe the synthesis and
characterization of five compounds containing
ncu.edu.cn.
c
ꢀ
2010 Wiley Periodicals, Inc.
423

424 Tang et al.
RESULTS AND DISCUSSION
Synthesis
The synthetic routes of compounds 1 and 2 are
shown in Scheme 1. Starting with o-methyl phenol,
product d was afforded through methylation, bromi-
nation, nucleophilic substitution, and reduction. In
the synthesis of compound c, sodium ethoxide was
used to deprotonate diethyl 2-methylmalonate by
following the literature procedure [10]. In spite of
a fairly good yield (ca. 50%) of this reaction, its un-
clean nature gave much difficulty in further purifica-
tion. This is probably due to reactivity of the ethox-
ide, which is able to attack the electrophilic carbon
adjacent to the bromine atom. However, when using
NaH in the deprotonation, the reaction was almost
quantitative (yielding 97%), and no further purifica-
tion was needed in the reduction of compound c to
give quantitatively a diol (d) (Scheme 1).
The preparation of compound d was initiated by
modeling chemistry of [FeFe]-hydrogenase in which
a dithiol ligand containing a phenol moiety was re-
quired to prepare a di-iron hexacarbonyl complex
by reacting the dithiol with Fe3(CO)12 by following
a general procedure [11,12]. The dibromide, 1-(3-
bromo-2-(bromomethyl)-2- methylpropyl) - 2- meth-
oxybenzene (1a), in principle, can be prepared
through either the substitution reaction of com-
pound e, which was achieved by tosylation of the
FIGURE 1 Compounds containing chroman and chromene
moieties: (i) flavone, (ii) benzopyran chalcone, (iii) coumarin,
and (iv) vitamin E (α-tocopherol).
chroman-liked moiety. In these compounds, various
groups as mimics of the phytyl chain in VE were
attached to the chroman-liked moiety. These
compounds were fully characterized. Cytotoxicity
of these compounds was estimated against two
cancer cell lines: human ovarian cancer (A2780)
and human cervical cancer (Hela) using MTT (3-
(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide) assay. Our results showed that these
compounds possess essentially no cytotoxic effect
on these examined cell lines, which suggests that
modifying the phytyl chain is not an effective
way to prepare VE analogues to achieve desired
cytotoxicity.
SCHEME 1 Synthetic routes for the formation of the chroman ring.
Heteroatom Chemistry DOI 10.1002/hc

Chroman-Containing Compounds and Their Preliminary Assessment of Cytotoxicity 425
diol (d) with KBr in DMF (Route 1) or bromina-
of VE analogues. It has also been proven that redox-
silent VE analogues in which the functional domain
was replaced with ethers (RO–), esters (RCOO ),
and amides (RCONH–) show anticancer activity via
destabilizing mitochondria [8,9]. The destabilization
induces apoptosis of tumor cells. The hydrophobic
domain, a long alkyl chain at C2, decides whether
the VE analogues can effectively bind to lipoproteins
and membranes or not. There is no doubt that such
an interaction plays an important role in rendering
the VE analogues’ anticancer activity. The synthe-
sized compounds 1 and 2 have functional groups at
C3, which can be further modified with other func-
tional groups. As shown in Fig. 1, VE contains a long
alkyl chain at C2. This similarity prompted us to ex-
plore whether the substituent at C3 will render any
enhancement in cytotoxicity. Thus a series of chro-
man derivatives were synthesized through the mod-
ification of the hydroxyl of compound 2. In princi-
ple, using compound 1 could also achieve the same
goal.
As shown in Scheme 3, functionalization of the
hydroxyl group of compound 2 led to compounds 3–
5. A long alkyl chain was introduced through the re-
action of 1-bromododecane with compound 2. Com-
pound 3 is supposed to have good lipophilicity and
similar to the lipophilic chain of VE. When com-
pound 2 was treated with chloroacetyl chloride in
the presence of NEt3, compound 3 was obtained in
good yield. The resultant compound 4 can react with
pyridin-2-ylmethanamine to generate compound 5
(Scheme 3).
tion of compound d in HBr acid (Route 2). But in
practice, Route 2 failed to lead to the desired di-
bromide. Instead, compound 2 was formed bearing
a chroman moiety via cyclization. While the dibro-
mide (1a) was obtained in ca. 41% yield, compound
1, structurally similar to compound 2, was isolated
as well in 30% yield when Route 1 was adopted. The
only difference between the two compounds is that
the hydroxyl group in compound 2 was replaced with
a bromine atom to give compound 1. This difference
suggests that the formation of these two chroman
derivatives may follow different mechanisms.
In Route 2, the diol was treated in concentrated
acidic medium at 140◦C. Under this harsh condi-
tion, a possible reaction pathway is that the hy-
droxyl is protonated to form oxonium salt. Among
the possible nucleophilic attacks by the O atom of
the methoxy group, the carbon atom adjacent to the
oxonium salt is the most favored target to form a
six-member ring via an intramolecular reaction and
subsequently a H2O molecule is cleaved to produce
compound 2. What is surprising in the formation
of compound 2 is that the other hydroxy group re-
mained intact during the reaction. For the formation
of compound 1, compound e with toluenesulfonate
(OTs), which is a good leaving group under mild
condition, was likely brominated first to afford the
desired dibromide. This dibromide would follow the
mechanism as that for the formation of compound
2 to give the corresponding oxonium bromide. Since
the bromide ion is a good nucleophile, it attacks the
methyl group of the oxonium ion to give CH3Br and
compound 1. Two mechanisms with subtle differ-
ences for the formation of compounds 1 and 2 are
depicted in Scheme 2.
Cytotoxic Assessment of Compounds 2–5
The cytotoxic investigations of these synthesized
chroman derivatives were performed using MTT
assay, and viable and nonviable cells were discrim-
inated to reflect the impact of a compound on cell
growth [13]. Unfortunately, preliminary investi-
gations turned out that none of the synthesized
Both compounds 1 and 2 possess a chroman
moiety, which is found in VE (Fig. 1). VE struc-
turally consists of functional, signaling, and hy-
drophobic domains. The functional domain, sub-
stituent at C6, is responsible for antioxidant activity
SCHEME 2 Possible mechanisms of the cyclization reactions.
Heteroatom Chemistry DOI 10.1002/hc

426 Tang et al.
SCHEME 3 Synthesis of the chroman derivatives.
TABLE 1 Cytotoxicity Effects of the Chroman Derivatives
EXPERIMENTAL
General Procedures
Compound
2
3
4
5
Reactions were carried out under argon atmosphere
by using the standard Schlenk technique when
necessary. Solvents were freshly distilled by using
appropriate drying agents prior to use. Infrared spec-
tral data were collected on Scimitar 2000 (Varian).
1H NMR spectra were recorded on Avance DRX-
400 (Bruker) and Bruker Avance 600. Microanaly-
sis service was provided by the Center of Analysis
and Testing at Nanchang University. MTT assay
was carried out at the Medical College, Nanchang
University.
Cell survival (1.0 × A2780 cells 100% 100% 100% 100%
10−4 mol L−1
Hela cells 100% 100% 100% 62%
)
compounds shows any cytotoxic efficacy to the
examined cell lines at the concentration of 1.0 ×
10−4 mol L−1 except for compound 5. Hela cell
line’s survival was 62% when the concentration of
compound 5 was 1.0 × 10−4 mol L−1 (Table 1). This
is probably due to the lack of functional domain
at position C6 of the synthesized compounds 1–5.
Our results suggest that the phytyl chain of the VE
analogues did not play a decisive role in anticancer
activity. For the cytotoxic activity of compound 5,
it may be attributed to the presence of the pyridine
ring, which existed as a ligand in some anticancer
agents such as coordination compounds of Pt and
Sn [14]. Indeed, some pyridine derivatives have
been proven to have anticancer activity [15].
Synthesis of o-CH3C6 H4OCH3, a
Dimethyl sulfate (22.7 mL, 240 mmol) was added
into a suspension of K2CO3 (26 g, 188 mmol) and
o-cresol (13 g, 120 mmol) in acetone (400 mL). (Cau-
tion: This reagent is toxic.) The reaction solution was
stirred at 75◦C overnight and then filtered and con-
centrated under vacuum to produce a crude product,
which was dissolved in a solution of NaOH (0.01 mol
L−1, 60 mL). The mixture was extracted with ethyl
acetate (4 × 60 mL). The organic phases were com-
bined and dried with MgSO4. The removal of the
solvents gave a colorless liquid (14 g, 96%). 1H NMR
(CDCl3, 400 MHz) (ppm): 7.16 (m, 2H, ArH), 6.84
(m, 2H, ArH), 3.82 (s, 3H, OCH ), 2.22 (s, 3H, CH ).
CONCLUSIONS
A series of chroman derivatives have been synthe-
sized and characterized using IR, NMR, and elemen-
tal analysis. Since these compounds posses struc-
tural similarity to that of VE, their cytotoxicities
against A2780 and Hela cell lines have been investi-
gated using MTT assay. Our results show that none
of these compounds exhibit any anticancer efficacy
except for that compound 5 showed slightly some ac-
tivity. These preliminary results suggest that in syn-
thesis of VE analogues, which may show anticancer
activity, the lipophilic domain may not be the essen-
tial concern.
3
3
Synthesis of o-H3COC6 H4CH2Br, b
A solution of compound a (7.3 g, 60 mmol), NBS
(N-bromosuccinimide) (10.7 g, 60 mmol), and AIBN
(azobisisobutyronitrile) (160 mg, 1 mmol) in CCl4
(250 mL) was heated under reflux for about 1 h
until a white solid started floating on the surface.
Heteroatom Chemistry DOI 10.1002/hc

Chroman-Containing Compounds and Their Preliminary Assessment of Cytotoxicity 427
The mixture was filtered, and then the filtrate was
Preparation of o-CH3OC6 H4CH2C(CH3)
(CH2OTs)2, e
concentrated under reduced pressure to produce a
residue. Recrystallizing the residue in hexane af-
A solution of compound d (6.5 g, 30 mmol) in pyri-
dine (100 mL) was cooled with an ice bath, and then
added with a solution of 4-toluene sulfonyl chloride
(TsCl, 40 g, 210 mmol) in pyridine (15 mL). After
being stirred at room temperature overnight, con-
centrated H2SO4 was dropwise added at ice temper-
ature till the smell of pyridine disappeared. The mix-
ture was then poured into an ice water (500 mL)
and then was left in a refrigerator for several hours.
A sticky liquid that adhered to the inner surface of
the container appeared. The aqueous phase was de-
canted off, and the oily liquid was extracted with
ethyl acetate (4 × 40 mL). The organic layer was
dried with MgSO4 and was concentrated under vac-
uum to give a sticky light yellow liquid (14.3 g, 90%).
IR (Nujol): S = O: 1361 cm−1 (s), 1189 cm−1 (s); C C
(Ph): 1599 cm−1 (s); C O C: 1096 cm−1 (s), 1245
1
forded a white solid (11.5 g, 93%). Mp: 47–50◦C. H
NMR (CDCl3, 600 MHz) (ppm): 7.30 (m, 2H, ArH),
6.92 (t, J = 7.2 Hz. 1H, ArH), 6.88 (d, J = 7.8 Hz, 1H,
ArH), 4.57 (s, 2H, 2 × CHH), 3.88 (s, 3H, OCH ). 13
C
3
NMR (CDCl3, 600 MHz) (ppm): 157.4, 130.9, 130.2,
126.1, 120.7, 111.0, 55.6, 29.1.
Synthesis of o-CH3OC6 H4CH2C(CH3)
(COOCH2CH3)2, c
Diethyl methylmalonate (5.2 mL, 30 mmol) was
added to a suspension of NaH (60% dispersion in
mineral oil, 2.9 g, 72 mmol) in THF (200 mL) at ice
temperature. (Caution: this reagent is toxic.) Then
a solution of compound b (6 g, 30 mmol) in THF
(10 mL) was added when there was no more hydro-
gen gas evolving. The reaction solution was stirred at
85◦C for about 3 h. Then the solvent was removed un-
der vacuum. Water (20 mL) was carefully added to
remove the excess NaH, and this aqueous solution
was extracted with ethyl acetate (4 × 30 mL). The
combined organic phases were dried with MgSO4
before the removal of the solvents to give a straw
yellow oily liquid (8.5 g, 97%). IR (Nujol): C O:
1
cm−1 (s). H NMR (CDCl3, 400 MHz) (ppm): 7.57
(d, J = 7.8 Hz, 4H, ArH), 7.15 (d, J = 7.8 Hz, 4H,
ArH), 6.97 (t, J = 7.5 Hz, 1H, ArH), 6.69 (d, J = 7.1
Hz, 1H, ArH), 6.61 (d, J = 8.1 Hz, 1H, ArH), 6.55
(t, J = 7.2 Hz, 1H, ArH), 3.69 (d, J = 9.5 Hz, 2H,
2 × CHH), 3.61 (d, J = 9.5 Hz, 2H, 2 × CHH), 3.50
(s, 3H, OCH ), 2.44 (s, 2H, CH ), 2.22 (s, 6H, 2 ×
3
2
PhCH ), 0.62 (s, 3H, CH ). 13C NMR (CDCl3, 400
3
3
1
1731.5 cm−1 (s), H NMR (CDCl3, 400 MHz) (ppm):
MHz) (ppm): 157.8, 145.0, 132.7, 132.2, 130.0, 128.3,
127.8, 123.8, 120.2, 110.6, 72.7, 54.9, 39.5, 33.1,
21.5, 18.2.
7.12 (t, J = 7.6 Hz, 1H, ArH), 6.98 (d, J = 7.2 Hz, 1H,
ArH), 6.75 (m, 2H, ArH), 4.10 (m, 4H, 2 × CH ), 3.68
2
(s, 3H, OCH ), 3.24 (s, 2H, CH ), 1.16 (s, 3H, CH ),
3
2
3
0.78 (t, J = 8.3 Hz, 6H, 2 × CH ).
Synthesis of 3-(Bromomethyl)-3-
methylchroman, 1
3
KBr (4.5 g, 38 mmol) was added to a solution of com-
pound e (2 g, 3.8 mmol) in DMF (15 mL). After being
stirred at 160◦C overnight, the reaction mixture was
concentrated under reduced pressure while it was
hot. Then the obtained residue was extracted with
ethyl acetate (4 × 30 mL). The organic phases were
combined and washed with brine. The removal of
the solvent under reduced pressure afforded a crude
product, which was purified with flash chromatog-
raphy (eluent: petroleum ether) to give compounds
1 (311 mg, 30%) and 1a (533 mg, 41%) both as light
Synthesis of o-CH3OC6 H4CH2C(CH3)
(CH2OH)2, d
An ice-chilled suspension of LiAlH4 (3.7 g,
100 mmol) in dried THF (200 mL) was added with
a solution of compound c (9.7 g, 33 mmol) in THF
(10 mL). After being stirred at 50◦C overnight, the
solvent was removed and the resultant residue was
treated with extreme care by addition of a solution
of NH4Cl (aq., sat., 30 mL) in dropwise manner to
consume any unreacted LiAlH4. The mixture was ex-
tracted with ethyl acetate (4 × 50 mL). The organic
phases were combined and then concentrated under
reduced pressure to produce a crude product that
was recrystallized in a diethyl ether/hexane system
to afford a white solid (6.8 g, 98%). 1H NMR (CDCl3,
400 MHz) (ppm): 7.25 (t, J = 7.4 Hz, 1H, ArH), 7.16
(d, J = 7.0 Hz, 1H, ArH), 6.95 (m, 2H, ArH), 3.89 (s,
1
yellow oily liquid. Compound 1: H NMR (CDCl3,
400 MHz) (ppm): 7.09 (t, J = 7.6 Hz, 1H, ArH), 7.01
(d, J = 7.4 Hz, 1H, ArH), 6.84 (m, 2H, ArH), 3.91
(q, 2H, 2 × CHH), 3.88 (q, 2H, 2 × CHH), 2.70 (m,
2H, 2 × CHH), 1.12 (s, 3H, CH ). Microanalysis for
3
C11H13BrO (FW (formula weight) = 240.01), calcd
(found): C%, 54.79 (54.64); H%, 5.43 (5.59).
Compound 1a: 1H NMR (CDCl3) (ppm): 7.22 (m,
3H, OCH ), 3.52 (q, 2H, 2 × CHH), 3.39 (q, 2H, 2 ×
3
CHH), 3.29 (t, J = 6.5 Hz, 2H, 2 × CH2OH), 2.81 (s,
2H, CH ), 0.73 (s, 3H, CH ).
2H, ArH), 6.88 (m, 2H, ArH), 3.79 (s, 3H, OCH ), 3.51
3
(d, J = 10.3 Hz, 2H, 2 × CHH), 3.43 (d, J = 10.3 Hz,
2
3
Heteroatom Chemistry DOI 10.1002/hc

428 Tang et al.
2H, 2 × CHH), 2.86 (s, 2H, CH ), 1.06 (s, 3H, CH ).
Preparation of (3-Methylchroman-3-yl)methyl
2-chloroacetate, 4
2
3
13C NMR (CDCl3): 158.0, 132.0, 128.2, 125.2, 120.4,
110.6, 55.1, 42.7, 40.0, 35.3, 21.8.
Chloroacetyl chloride (2 mL, 25 mmol) was added to
a solution of compound 2 (415 mg, 2.3 mmol) and
triethylamine (2 mL, 15 mmol) in dichloromethane
(20 mL). After being stirred at room temperature for
1 h, a solution of NaHCO3 (aq., sat.) was added to re-
move the unreacted chloroacetyl chloride. Then the
mixture was extracted with dichloromethane (3 ×
20 mL). The organic phases were combined and were
concentrated to give a crude product, which was pu-
rified by flash chromatography (eluent: petroleum
ether: ethyl acetate = 10:1) to afford a colorless oily
Synthesis of (3-Methylchroman-3-yl)methanol, 2
A mixture of compound d (2.1 g, 10 mmol) and HBr
(48%, 70 mL) were heated at 140◦C for about 3 h.
After being cooled to room temperate, a solution of
NaHCO3 (aq., sat.) was added to neutralize the ex-
cess HBr. Then the mixture was extracted with ethyl
acetate (4 × 50 mL). The organic layers were com-
bined and were concentrated under reduced pres-
sure to give a residue, which was purified using
column chromatography (eluent: petroleum ether:
ethyl acetate = 3:1). Recrystallization in diethyl ether
gave a white solid (1.4 g, 79%). 1H NMR (CDCl3, 400
MHz) (ppm): 7.10 (t, J = 7.6 Hz, 1H, ArH), 7.03
(d, J = 7.4 Hz, 1H, ArH), 6.84 (m, 2H, ArH), 3.91
(q, 2H, 2 × CHH), 3.51 (m, 2H, 2 × CHH), 2.60
(q, 2H, 2 × CHH), 1.60 (m, 1H, OH), 1.05 (s, 3H,
1
liquid (415 mg, 58%). H NMR (CDCl3 600 MHz)
(ppm): 7.10 (m, 1H, ArH), 7.02 (m, 1H, ArH), 6.87
(m, 1H, ArH), 6.82 (q, 1H, ArH), 4.08 (m, 4H, 4 ×
CHH), 3.91 (q, 2H, 2 × CHH), 2.60 (q, 2H, 2 × CHH),
1.07 (s, 3H, CH ). 13C NMR (CDCl3, 400 MHz) (ppm):
3
169.9, 152.6, 129.0, 126.3, 119.7, 119.2, 115.5, 70.3,
67.1, 52.4, 33.4, 31.3, 19.7, 19.4.
CH ). 13C NMR (CDCl3): 153.9, 130.1, 127.2, 120.9,
3
Synthesis of Bis((3-methylchroman-3-yl)methyl)
120.6, 116.5, 71.5, 67.3, 34.2, 33.8, 20.3. Microanal-
ysis for C11H14O2, (FW = 178.23), calcd (found): C%,
74.13 (74.09); H%, 7.92 (7.84).
2,2ꢁ-((pyridin-2-yl-methyl) azanediyl)diacetate, 5
A solution of compound 4 (425 mg, 1.7 mmol)
in MeCN (10 mL) was added to a suspension
of K2CO3 (460 mg), KI (550 mg), and pyridin-
2-ylmethanamine (192 μL, 1.68 mmol) in MeCN
(30 mL). The mixture was stirred under reflux
overnight. After removal of the inorganic salt by fil-
tration, the filtrate was concentrated under reduced
pressure to give a crude product, which was puri-
fied by flash chromatography (eluant: ethyl acetate)
Preparation of 3-(Dodecyloxy)methyl)-3-
methylchroman, 3
Compound 2 (177 mg, 1 mmol) was added to
a suspension of NaH (60% dispersion in mineral
oil, 100 mg, 2.5 mmol) in THF (20 mL) at ice
temperature. When hydrogen bubbling stopped, 1-
bromododecane (240 μL, 1.25 mmol) was added. The
mixture was stirred under reflux for 3 h and then
was concentrated under reduced pressure. Distilled
water (10 mL) was carefully added to remove the
excess NaH. Then the mixture was extracted with
ethyl acetate (3 × 10 mL). The organic phases were
combined and were concentrated under vacuum to
give a crude product, which was purified by flash
chromatography to give a colorless liquid (220 mg,
1
to give a yellow oily liquid (yield, 42%). H NMR
(CDCl3, 600 MHz) (ppm): 8.50 (s, 1H, PyH), 7.64
(m, 2H, 2 × PyH), 7.15 (t, J = 5.7 Hz, 1H, PyH), 7.06
(t, J = 7.2 Hz, 2H, 2 × ArH), 6.99 (d, J = 7.2 Hz, 2H,
2 × ArH), 6.82 (m, 4H, 4 × ArH), 4.01 (m, 8H, 8 ×
CHH), 3.68 (q, 4H, 4 × CHH), 2.60 (q, 4H, 4 × CHH),
1.01 (s, 6H, 2 × CH ). 13C NMR (CDCl3, 400 MHz)
3
(ppm): 171.0, 158.7, 153.6, 149.1, 136.7, 130.0, 127.4,
123.1, 122.3, 120.8, 120.1, 116.5, 71.4, 68.3, 59.9,
54.7, 53.5, 34.4, 32.4, 20.5, 14.2. Microanalysis for
C32H36N2O6 (FW = 544.26), calcd (found): C%, 70.57
(69.43); H%, 6.66 (6.55); N%, 5.14 (4.95)
1
65%). H NMR (CDCl3, 600 MHz) (ppm): 7.07 (m,
1H, ArH), 7.01 (d, J = 7.8 Hz, 1H, ArH), 6.82 (m,
2H, 2 × ArH), 3.87 (q, 2H, 2 × CHH), 3.37 (m, 2H,
2 × CHH), 3.34 (q, 2H, 2× CHH), 2.59 (q, 2H, 2 ×
CHH), 1.54 (m, 2H, 2 × CHH), 1.29 (m, 18H, 18 ×
CHH), 1.03 (s, 3H, CH ), 0.88 (m, 3H, CH ). 13C NMR
MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-
tetrazolium bromide) Assay
3
3
(CDCl3, 400 MHz) (ppm): 154.0, 130.1, 127.1, 121.4,
120.4, 116.4, 75.3, 72.0, 71.8, 34.6, 33.3, 32.0, 29.7,
29.5, 29.4, 26.2, 22.7, 20.8, 14.2. Microanalysis for
C23H38O2 (FW = 346.29), calcd (found): C%, 79.71
(79.54); H%, 11.05 (11.06).
For the in vitro cell viability assays, A2780 and
Hela cell lines were employed. Both cell lines were
grown in 1640 medium, supplemented with 10%
foetal bovine serum under 5% CO2 and aseptic
Heteroatom Chemistry DOI 10.1002/hc

Chroman-Containing Compounds and Their Preliminary Assessment of Cytotoxicity 429
conditions at 37◦C. The cells were seeded at a
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ACKNOWLEDGMENTS
We thank the Natural Science Foundation of China
(Grant No. 20571038, 20871064) and the Centre of
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Heteroatom Chemistry DOI 10.1002/hc