Synthesis of podands with cyanurate or isocyanurate cores and terminal triple bonds

Article abstract of DOI:10.1055/s-0029-1218724

The synthesis of podands with cyanuric or isocyanuric acid cores and oligoethyleneoxy pendant arms exhibiting terminal triple bonds or brominated triple bonds is reported. The starting material for cyanuric acid derived podands is commercially available c

Full text of DOI:10.1055/s-0029-1218724

PAPER
1639
Synthesis of Podands with Cyanurate or Isocyanurate Cores and Terminal
Triple Bonds
Podands
with
l
a
a
te and
I
soc
v
yanurate Co
i
res a Piron,a,b Cornelia Oprea,a Crina Cismaş,*a Anamaria Terec,a Jean Roncali,b Ion Grosu*a
a
Babes-Bolyai University, Organic Chemistry Department and CCOCCAN, Cluj-Napoca, 11 Arany Janos str., 400028 Cluj-Napoca,
Romania
b
University of Angers, CNRS, CIMA, Group Linear Conjugated Systems, 2 Bd Lavoisier, 49045 Angers, France
Fax +40(264)590818.; E-mail: csocaci@chem.ubbcluj.ro; E-mail: igrosu@chem.ubbcluj.ro
Received 11 February 2010
The core of the two series of tripodands exhibit different
properties: the 1,3,5-triazine unit I is an electron-poor het-
eroaromatic system, while the isocyanurate core II can
participate, via the oxygen atoms, as a donor for the for-
Abstract: The synthesis of podands with cyanuric or isocyanuric
acid cores and oligoethyleneoxy pendant arms exhibiting terminal
triple bonds or brominated triple bonds is reported. The starting ma-
terial for cyanuric acid derived podands is commercially available
cyanuric acid, while the isocyanuric derivatives are obtained by mation of hydrogen bonds.10 The attachment of functional
thermal isomerization of the corresponding cyanurates.
groups (X = Br) to the terminal triple bonds opens the way
to many other possible synthetic approaches and makes
these compounds important precursors for host mole-
cules, macromolecules, and dendrimers with C3 symme-
try.
Key words: podands, cyanurates, alkynes, isomerization, heterocy-
cles
In this work we have investigated the synthesis of tripo-
dands with terminal triple bonds and cyanuric I or isocy-
anuric acids II as cores, targeted to be useful
intermediates for further functionalization in order to
achieve a plethora of macromolecular or supramolecular
compounds (Figure 1).1–9
The investigated synthetic strategies utilize consecutive
reactions, they are based on an inexpensive commercially
available starting compound (cyanuric chloride), and the
results have been compared with other methodologies,
which failed or gave poor results.
Trialkoxycyanurates have long been known,11 their syn-
thesis requires the reaction of silver cyanurates with alkyl
halides, trimerization of imidates, and, most commonly
used, the nucleophilic substitution of the chlorine in cya-
nuric chloride with alkoxides.
X
Given the availability of cyanuric chloride, we focused
our investigations on the possibility of obtaining com-
pounds 2a–e (Scheme 1) by nucleophilic substitution of
the chlorines of cyanuric chloride with alkoxides having
oligoethyleneoxy chains and a terminal triple bond.
O
N
N
X
X
O
N
O
I
X = H, Br
spacer
X
O
O
H
O
n
O
N
Cl
N
1a
–e
N
N
N
N
n-BuLi, THF
O
O
O
O
Cl
Cl
n
n
O
N
O
2a, n = 0 (65%)
2b, n = 1 (63%)
2c, n = 2 (63%)
2d, n = 3 (57%)
2e, n = 4 (55%)
N
N
X
X
O
II
Scheme 1
Figure 1
The cyanurate 2a was previously synthesized12 from cya-
nuric chloride and propargyl alcohol in acetone using so-
dium hydroxide as base. Compound 2a was later used as
an intermediate for the construction of dendrimers.13 At-
tempts to obtain 2a and other compounds 2 of the series
SYNTHESIS 2010, No. 10, pp 1639–1644
Advanced online publication: 06.04.2010
DOI: 10.1055/s-0029-1218724; Art ID: P01810SS
© Georg Thieme Verlag Stuttgart · New York
x
x.
x
x
.
2
0
1
0

1640
F. Piron et al.
PAPER
using this reported procedure gave poor or moderate
yields. The other procedures reported for the formation of
trialkoxycyanurates starting from cyanuric chloride with
alcohols use sodium hydride,14 sodium hydroxide, N,N-
diisopropylethylamine,15 or potassium tert-butoxide16 as
the base and require a large excess of alcohol. Due to the
use of a large excess of alcohol, these procedures were
considered unsuitable for the synthesis of 2a–e.
X
O
N
O
n
O
4b–d, 5b–d
O
N
O
O
X
HN
NH
N
X = Cl, I
O
O
n
O
N
H
O
n
3b–d
The high yielding synthesis of trialkoxycyanurates start-
ing from cyanuric chloride with alcohols using butyllithi-
um as a base has been recently reported.17 We adapted this
method for our target compounds and carried out the syn-
thesis of 2a–e in tetrahydrofuran with stoichiometric
amounts of the appropriate alcohol. The yields increased
considerably (55–65%) when compared to other
methods12 and the separation and purification of the prod-
ucts was substantially facilitated (Scheme 1).
Scheme 3
The chloro derivatives 4b and 4d are known com-
pounds.25,26 The procedure reported for 4d26 was used also
for the synthesis of 4c, providing 4c,d in good yields (70–
85%) (Scheme 4). The iodo compounds 5b–d were syn-
thesized (60–80% yields) by a standard procedure27 for
the halogen-exchange reaction (Scheme 4). Compounds
5c,d have not been previously reported, while 5b was re-
The precursor alcohols 1b–e were synthesized using pro-
cedures described in the literature18 while propargyl alco-
hol 1a is commercially available.
cently obtained by another procedure (using OTs for I–
–
exchange).28
As shown in the literature, isocyanuric acid derivatives
can be formed by trimerization of isocyanates,19 by substi-
tution under harsh conditions at cyanuric acid,20 or by re-
arrangement of the corresponding cyanurates.21,22
NaH
THF
Cl
Cl
O
H
O
propargyl
bromide
n
n
4b, n = 1
4c, n = 2
4d, n = 3
The hitherto unknown isocyanurate derivatives 3b–d
(Scheme 2) were obtained by the rearrangement reaction
from cyanurates 2b–d, in a process catalyzed by tetrabu-
tylammonium bromide or tetrabutylphosphonium bro-
mide at 120 °C without solvent. Even though there are
reports that such thermal isomerizations occur using sol-
vents at temperatures higher than 100 °C,22 the treatment
of cyanurates 2 in toluene or xylene under reflux gave no
isocyanurates 3. This type of reaction was previously de-
scribed by Harrington et al.21 for the isomerization of oth-
er 1,3,5-triazine derivatives.
I
O
n
NaI, acetone
n = 1,2,3
5b, n = 1
5c, n = 2
5d, n = 3
Scheme 4
As another alternative synthetic route to isocyanuric acid
derivatives 3, a side chain nucleophilic substitution of
commercially available 1,3,5-tris(2-hydroxyethyl)cyanu-
ric acid (6) with propargyl bromide and iodo derivatives
5b–d was considered. Only the reaction with propargyl
bromide in the presence of sodium hydride (DMSO, 20
°C) afforded the isocyanurate 3b, together with the ox-
azolidone 7 (Scheme 5). In the other reactions (iodo deriv-
atives 5b–d), no isocyanurates were isolated from the
reaction mixtures. The cleavage of the tris(2-hydroxyeth-
yl)isocyanurate heterocycle involved in the formation of 7
is likely to occur by nucleophilic attack of the deprotonat-
ed side chain hydroxy group on the carbonyl site with in
situ formation of the unsubstituted oxazolidone, which is
further deprotonated and propargylated. Similar behavior,
but without alkylation, was previously observed for 2-hy-
droxyethyl isocyanurates on vacuum pyrolysis29 and on
heating in N,N-dimethylformamide solution at high tem-
peratures.30 In our case working at 35–40 °C gave the ox-
azolidone 7 as the major product while the isocyanurate
3b was formed predominantly at room temperature (20
°C).
O
O
Bu4PBr or
Bu4NBr
O
O
N
O
O
N
N
N
N
O
O
n
O
O
O
N
O
n
n
n
2b, n = 1
2c, n = 2
2d, n = 3
3b, n = 1
3c, n = 2
3d, n = 3
Scheme 2
As an alternative route to the isocyanurate derivatives 3b–
d, the alkylation of cyanuric acid with propargyloligo(eth-
yleneoxy)ethyl halides 4b–d and 5b–d was attempted
(Scheme 3). Despite the successful synthesis reported for
3a,23 all attempts to alkylate cyanuric acid under various
basic conditions (KOH, NaH)24 with the chlorides 4b–d
or the iodides 5b–d failed.
The structures of the new cyanurates 2a–e and their iso-
mers isocyanurates 3b–d were confirmed by NMR spec-
troscopy. The main differences between the spectra of
Synthesis 2010, No. 10, 1639–1644 © Thieme Stuttgart · New York

PAPER
Podands with Cyanurate and Isocyanurate Cores
1641
The structure of the brominated products 8a–c and 9a,b
was elucidated by NMR spectroscopy. Thus, the absence
of signals for the protons of the terminal triple bonds in 1H
NMR spectra, the upfield shift of the signals belonging to
the sp carbon atoms in 13C NMR and the specific pattern
for the tribrominated peaks in MS were noted (see exper-
imental section).
O
N
O
N
O
OH
N
O
O
NaH, DMSO
Br
O
O
N
O
An efficient synthesis of C3 symmetry podands with pen-
dant arms of different lengths (n = 0–4) bearing at their
extremities triple bonds, either brominated or not, and ex-
hibiting 1,3,5-triazine or 1,3,5-triazinane-2,4,6-trione
cores is reported. Starting from cyanuric chloride, an in-
expensive commercially available compound, diverse po-
dands could be obtained in a few consecutive steps. The
compounds described in this paper represent promising
versatile starting materials for functionalized podands
and/or cryptands by subsequent reactions, such as copper-
catalyzed [2+3] cycloaddition with azides or oxidative
copper-catalyzed homocoupling, Sonogshira, and other
palladium-catalyzed cross-coupling reactions.
3b
N
N
+
HO
OH
O
O
6
N
O
3
7
Scheme 5
these two series were observed in the 13C NMR spectra
where the quaternary C=O carbons in isocyanurates give
signals at d = 148–149 compared with C–O signals of the
corresponding cyanurates which are considerably more
deshielded (d = 172–173). Similarly for the CH2N carbon
atoms of the isocyanurates 3 the 13C NMR signals are in
the range d = 41–42 (the corresponding protons show sig-
nals at d = 4.10–4.15), while the signals for the CH2O
moieties of cyanurates 2 are more deshielded (13C NMR,
d = 67–70 and 1H NMR, d = 4.51–4.55).
1H and 13C NMR spectra were recorded on a Bruker Avance 300
spectrometer operating at 300 MHz (1H) and 75 MHz (13C) relative
to TMS. MS were recorded on an ESI ion trap mass spectrometer
(Agilent 6320) in positive mode and in EI mode (70eV) on a VG-
Autospec mass spectrometer or in positive ionization on a Thermo-
Finnigan MSQ mass spectrometer. Solvents were dried and distilled
under argon using standard procedures before use. Chemicals of
commercial grade were used without further purification. Melting
points are uncorrected. Column chromatography purifications were
carried out on Merck silica gel Si 60 (40–63 mm). TLC was carried
out on aluminum plates coated with silica gel 60 F254 using UV
lamp (254 nm) and KMnO4 visualization.
In order to access C3 podands with extended capacity for
further applications (e.g., cross-coupling reactions), bro-
mination of the terminal CH of the triple bonds in com-
pounds 2a–c and 3a,b was envisaged (Scheme 6). The
reactions were carried out in fair to good yields (30–70%)
with N-bromosuccinimide in the presence of silver nitrate.
An excess of N-bromosuccinimide (250%) was used in or-
der to enhance the ratio of triple substitution products.
Podands 2 with 1,3,5-Triazine Units; General Procedure
A soln of 15% n-BuLi in hexane (3.34 mL, 5.32 mmol) was slowly
added to the soln of hydroxy alkyne 1b–e (5.32 mmol) in anhyd
THF (40 mL) under an argon atmosphere at –78 °C. The lithium
alkoxide soln was stirred at this temperature for 15 min and then cy-
anuric chloride (327.2 mg, 1.77 mmol) in anhyd THF (10 mL) was
added dropwise over 5 min. The mixture was stirred overnight at r.t.
The solvent was removed and the residue was washed with H2O (50
mL), extracted with CH2Cl2, dried (Na2SO4), and concentrated.
Br
O
O
O
N
NBS
O
N
AgNO3
N
n
N
N
n
N
O
O
2,4,6-Tris(prop-2-ynyloxy)-1,3,5-triazine (2a)
O
O
O
O
n
O
O
Following the general procedure with purification by column chro-
matography (silica gel, pentane–EtOAc, 9:1); white solid (65%);
mp 69–70 °C (Lit.13 69–70 °C); Rf = 0.35 (pentane–EtOAc, 9:1).
1H NMR (300 MHz, CDCl3): d = 2.53 (t, J = 2.4 Hz, 3 H), 5.04 (d,
J = 2.4 Hz, 6 H).
n
2a, n = 0
2b, n = 1
2c, n = 2
8a, n = 0
8b, n = 1
8c, n = 2
Br
Br
13C NMR (75 MHz, CDCl3): d = 58.8 (CH2), 75.8 (CH), 76.8 (C),
172.3 (CO).
Br
Anal. Calcd for C12H9N3O3: C, 59.26; H, 3.73; N, 17.28. Found: C,
59.43; H, 3.58; N, 17.44.
O
O
Br
n
Br
2,4,6-Tris(3-oxahexa-5-ynyloxy)-1,3,5-triazine (2b)
O
N
O
N
O
N
O
NBS
Following the general procedure with purification by column chro-
matography (silica gel, Et2O–acetone–hexane, 4:1:1); white solid
(63%); mp 96–97 °C; Rf = 0.35 (Et2O–acetone–hexane, 4:1:1).
AgNO3
N
N
N
O
O
O
O
n
n
n
O
O
1H NMR (300 MHz, CDCl3): d = 2.43 (t, J = 2.4 Hz, 3 H), 3.86 (t,
J = 4.8 Hz, 6 H), 4.21 (d, J = 2.4 Hz, 6 H), 4.55 (t, J = 4.8 Hz, 6 H).
3a, n = 0
3b, n = 1
9a, n = 0
9b, n = 1
Scheme 6
Synthesis 2010, No. 10, 1639–1644 © Thieme Stuttgart · New York

1642
F. Piron et al.
PAPER
13C NMR (75 MHz, CDCl3): d = 58.4 (CH2), 67.1, 67.2 (CH2CH2),
74.8 (CH), 79.1 (C), 172.8 (CO).
Anal. Calcd for C18H21N3O6: C, 57.59; H, 5.64; N, 11.19. Found: C,
57.80; H,5.41; N, 11.03.
MS (ESI): m/z = 376.1 [M + H]+.
1,3,5-Tris(3,6-dioxanona-8-ynyl)-1,3,5-triazinane-2,4,6-trione
(3c)
Following the general procedure with purification by column chro-
matography (silica gel, pentane–EtOAc, 1:1); yellow liquid (33%);
Rf = 0.64 (EtOAc–pentane, 1:1).
1H NMR (300 MHz, CDCl3): d = 2.42 (t, J = 2.4 Hz, 3 H), 3.68 (m,
12 H), 3.71 (t, J = 4.5 Hz, 6 H), 4.10 (t, J = 4.5 Hz, 6 H), 4.17 (d,
J = 2.1 Hz, 6 H).
13C NMR (75 MHz, CDCl3): d = 41.6 (NCH2), 58.3 (OCH2), 67.4
(OCH2), 69.0, 69.8 (CH2CH2), 74.5 (CH), 79.6 (C), 149.0 (C=O).
MS (ESI): m/z = 508.4 [M + H]+, 530.4 [M + Na]+, 546.3 [M + K]+.
Anal. Calcd for C18H21N3O6: C, 57.59; H, 5.64; N, 11.19. Found: C,
57.37; H, 5.48; N, 11.35.
2,4,6-Tris(3,6-dioxanona-8-ynyloxy)-1,3,5-triazine (2c)
Following the general procedure with purification by column chro-
matography (silica gel, Et2O–acetone–hexane, 4:1:1); colorless liq-
uid (63%); Rf = 0.35 (Et2O–acetone–hexane, 4:1:1).
1H NMR (300 MHz, CDCl3): d = 2.40 (t, J = 2.4 Hz, 3 H), 3.65–
3.67 (m, 12 H), 3.78–3.81 (m, 6 H), 4.16 (d, J = 2.4 Hz, 6 H), 4.48–
4.52 (m, 6 H).
13C NMR (75 MHz, CDCl3): d = 58.3 (CH2), 67.3, 68.7, 68.9, 70.4
(CH2CH2), 74.5 (CH), 79.4 (C), 172.8 (CO).
MS (ESI): m/z = 508.2 [M + H]+.
Anal. Calcd for C24H33N3O9: C, 56.80; H, 6.55; N, 8.28. Found: C,
56.65; H, 6.81; N, 8.39.
Anal. Calcd for C24H33N3O9: C, 56.80; H, 6.55; N, 8.28. Found: C,
56.96; H, 6.78; N, 8.19.
1,3,5-Tris(3,6,9-trioxadodeca-11-ynyl)-1,3,5-triazinane-2,4,6-
trione (3d)
Following the general procedure with purification by column chro-
matography (silica gel, pentane–EtOAc, 1:1); yellow liquid (20%);
Rf = 0.5 (EtOAc–pentane, 1:1).
1H NMR (300 MHz, CDCl3): d = 2.43 (t, J = 2.4 Hz, 3 H), 3.61–
6.71 (m, 30 H), 4.09 (t, J = 4.5 Hz, 6 H), 4.19 (d, J = 2.4 Hz, 6 H).
13C NMR (75 MHz, CDCl3): d = 41.6 (NCH2), 58.4 (OCH2), 67.4,
69.1, 69.9, 70.4, 70.6 (CH2CH2), 74.5 (CH), 149.0 (C=O).
2,4,6-Tris(3,6,9-trioxadodeca-11-ynyloxy)-1,3,5-triazine (2d)
Following the general procedure with purification by column chro-
matography (silica gel, Et2O–acetone–hexane, 4:1:1); colorless liq-
uid (57%); Rf = 0.3 (Et2O–acetone–hexane, 4:1:1).
1H NMR (300 MHz, CDCl3): d = 2.42 (t, J = 2.4 Hz, 3 H), 3.65–
3.66 (m, 24 H), 3.76–3.82 (m, 6 H), 4.17 (d, J = 2.4 Hz, 6 H), 4.49–
4.52 (m, 6 H).
13C NMR (75 MHz, CDCl3): d = 58.3 (CH2), 67.4, 68.8, 69.0, 70.4,
70.5, 70.6 (CH2CH2), 74.4 (CH), 79.4 (C), 172.9 (C–O).
MS (ESI): m/z = 640.3 [M + H]+, 662.3 [M + Na]+.
MS (ESI): m/z = 640.4 [M + H]+.
Anal. Calcd for C30H45N3O12: C, 56.33; H, 7.09; N, 6.57. Found: C,
56.29; H, 7.21; N, 6.51.
Anal. Calcd for C30H45N3O12: C, 56.33; H, 7.09; N, 6.57. Found: C,
56.51; H, 6.98; N, 6.76.
Chloroalkynes 4; General Procedure
Chloropoly(ethoxy)ethanol (20 mmol) was added dropwise to a
soln of 95% NaH (0.97 g, 40 mmol) in anhyd THF (50 mL) at –20
°C under an argon atmosphere. After 15 min at –78 °C, 80% prop-
argyl bromide soln (2.97 g, 20 mmol) was added dropwise and the
mixture was refluxed for 2 h. The mixture was concentrated by
evaporation in vacuo, washed with H2O (50 mL), and extracted with
CH2Cl2. The organic layer was dried (Na2SO4) and concentrated
and the resulting residue was purified by chromatography (silica
gel, pentane–Et2O, 4:1).
2,4,6-Tris(3,6,9,12-tetraoxapentadec-14-ynyloxy)-1,3,5-triaz-
ine (2e)
Following the general procedure with purification by column chro-
matography (silica gel, Et2O–acetone–hexane, 4:1:1); colorless liq-
uid (55%); Rf = 0.35 (Et2O–acetone–hexane, 4:1:1).
1H NMR (300 MHz, CDCl3): d = 2.42 (t, J = 2.4 Hz, 3 H), 3.64–
3.67 (m, 36 H), 3.80–3.83 (m, 6 H), 4.18 (d, J = 2.4 Hz, 6 H), 4.49–
4.53 (m, 6 H).
13C NMR (75 MHz, CDCl3): d = 58.3 (CH2), 67.4, 68.8, 69.1, 70.3,
70.5 (3 C) (CH2CH2), 70.6 (CH2), 74.4 (CH), 79.6 (C), 172.9 (CO).
MS (ESI): m/z = 772.3 [M + H]+, 794.3 [M + Na]+.
1-Chloro-3,6-dioxanona-8-yne (4c)
Following the general procedure; colorless liquid (70%); Rf = 0.56
(pentane–Et2O, 4:1).
1H NMR (300 MHz, CDCl3): d = 2.43 (t, J = 2.1 Hz, 1 H), 3.61–
3.77 (m, 8 H), 4.20 (d, J = 2.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 42.3 (ClC), 57.1 (OC), 68.5, 69.9,
70.8 (CH2CH2), 74.3 (CH), 78.1 (C).
Anal. Calcd for C36H57N3O15: C, 56.02; H, 7.44; N, 5.74. Found: C,
55.88; H, 7.59; N, 5.57.
Isocyanurate Podands 3; General Procedure
Anal. Calcd for C7H11ClO2: C, 51.70; H, 6.82; Cl, 21.80. Found: C,
51.98; H, 6.74; Cl, 21.93.
Derivatives 2b–d (0.66 mmol) and Bu4NBr (53 mg, 0.2 mmol) or
Bu4PBr (67.8 mg, 0.2 mmol) were stirred at 125 °C for 48 h. The
mixture was extracted with CH2Cl2 and, after washing with H2O,
the organic layer was concentrated.
Iodoalkynes 5; General Procedure
Chloroalkynes 4b–d (17 mmol) and anhyd NaI powder (10.2 g, 68
mmol) were refluxed in anhyd acetone (170 mL) for 48–68 h. The
solvent was removed and the crude mixture was washed with H2O
and extracted with CH2Cl2. The organic layer was dried (Na2SO4)
and the solvent removed under reduced pressure. The products were
purified by chromatography (silica gel, pentane–Et2O, 4:1).
1,3,5-Tris(3-oxahexa-5-ynyl)-1,3,5-triazinane-2,4,6-trione (3b)
Following the general procedure with purification by column chro-
matography (silica gel, pentane–EtOAc, 1:2); colorless liquid
(20%); Rf = 0.4 (EtOAc–pentane, 1:2).
1H NMR (300 MHz, CDCl3): d = 2.42 (t, J = 2.4 Hz, 3 H), 3.78 (t,
J = 5.4 Hz, 6 H), 4.13 (t, J = 5.4 Hz, 6 H), 4.16 (d, J = 2.1 Hz, 6 H).
1-Iodo-3,6-dioxanona-8-yne (5c)
Following the general procedure; brown liquid (60%); Rf = 0.5
(pentane–Et2O, 4:1).
13C NMR (75 MHz, CDCl3): d = 41.7 (NCH2), 57.8 (OCH2), 65.9
(OCH2), 74.7 (CH), 79.2 (C), 148.9 (C=O).
MS (APCI): m/z = 376.3 [M + H]+.
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PAPER
Podands with Cyanurate and Isocyanurate Cores
1643
1H NMR (300 MHz, CDCl3): d = 2.42 (t, J = 2.1 Hz, 1 H), 3.27 (t,
J = 6.9 Hz, 2 H), 3.65–3.76 (m, 6 H), 4.19 (d, J = 2.4 Hz, 2 H).
1H NMR (300 MHz, CDCl3): d = 3.86 (t, J = 3.6 Hz, 6 H), 4.25 (s,
6 H), 4.56 (t, J = 3.6 Hz, 6 H).
13C NMR (75 MHz, CDCl3): d = 2.7 (ICH2), 58.2 (OCH2), 68.8,
69.7, 71.7 (CH2CH2), 74.5 (CH), 79.3 (C).
13C NMR (75 MHz, CDCl3): d = 46.6 (CBr), 59.4 (OCH2), 67.1,
67.4 (CH2CH2), 75.8 (C), 172.9 (CO).
Anal. Calcd for C7H11IO2: C, 33.09; H, 4.36; I, 49.95. Found: C,
33.27; H, 4.29; I, 50.11.
MS (ESI): m/z (%) = 610.0 (42), 612.0 (100), 614.0 (91), 616.0 (31)
([M + H]+), 631.9 (19), 633.9 (53), 635.9 (54), 637.9 (18) ([M +
Na]+).
1-Iodo-3,6,9-trioxadodec-11-yne (5d)
Following the general procedure; brown liquid (79%); Rf = 0.38
(pentane–Et2O, 4:1).
Anal. Calcd for C18H18Br3N3O6: C, 35.32; H, 2.96; Br, 39.16; N,
6.87. Found: C, 35.17; H, 3.08; Br, 39.39; N, 6.93.
1H NMR (300 MHz, CDCl3): d = 2.42 (t, J = 2.1 Hz, 1 H), 3.24 (t,
J = 6.6 Hz, 2 H), 3.64–3.76 (m, 10 H), 4.19 (d, J = 2.4 Hz, 2 H).
2,4,6-Tris(9-bromo-3,6-dioxanona-8-ynyloxy)-1,3,5-triazine
(8c)
Following the general procedure with purification by column chro-
matography (silica gel, toluene–acetone, 4:1); colorless liquid
(20%); Rf = 0.31 (toluene–acetone, 4:1).
1H NMR (300 MHz, CDCl3): d = 3.68–3.71 (m, 12 H), 3.82–3.84
(m, 6 H), 4.22 (s, 6 H), 4.53–4.55 (m, 6 H).
13C NMR (75 MHz, CDCl3): d = 2.8 (ICH2), 58.1 (OCH2), 68.8,
69.9, 70.2, 70.3, 71.6 (CH2CH2), 74.4 (CH), 79.4 (C).
Anal. Calcd for C9H15IO3: C, 36.26; H, 5.07; I, 42.57. Found: C,
36.61; H, 4.88; I, 42.69.
3-(Prop-2-ynyl)oxazolidin-2-one (7)
13C NMR (75 MHz, CDCl3): d = 46.1 (CBr), 59.4 (OCH2), 67.4,
NaH 95% (1.72 g, 8.4 mmol) was slowly added to a soln of 1,3,5-
tris(2-hydroxyethyl)cyanuric acid (6 g, 22.8 mmol) in anhyd
DMSO (50 mL) under an argon atmosphere and cooling with ice,
without freezing the solvent. The mixture was stirred at r.t. for 1 h
and then 80% propargyl bromide in toluene (10.17 g, 68.4 mmol)
was added dropwise at 35–40 °C and the mixture was stirred for 2
h. The mixture was washed with H2O (3 × 50 mL) and extracted
with CH2Cl2. The organic layer was concentrated and the crude
product was purified by column chromatography (silica gel,
EtOAc–pentane, 1:2). The first collected fraction was compound
3b, colorless liquid (20%), Rf = 0.40 (EtOAc–pentane, 1:2), fol-
lowed by compound 7, colorless liquid (31%), Rf = 0.30 (EtOAc–
pentane, 1:2).
68.8, 69.2, 70.5 (CH2CH2), 76.1 (C), 172.9 (CO).
MS (ESI): m/z (%) = 742.1 (35), 744.0 (100), 746.0 (90), 747.9 (31)
([M + H]+), 763.9 (6), 765.9 (10), 767.9 (11), 770.0 (3) [M + Na]+.
Anal. Calcd for C24H30Br3N3O9: C, 38.73; H, 4.06; Br, 32.21; N,
5.65. Found: C, 38.55; H, 4.19; Br, 32.34; N, 5.49.
1,3,5-Tris(3-bromoprop-2-ynyl)-1,3,5-triazinane-2,4,6-trione
(9a)
Following the general procedure with purification by column chro-
matography (silica gel, toluene–acetone, 9:1); white solid (45%);
mp 79–81 °C; Rf = 0.6 (toluene–acetone, 9:1).
1H NMR (300 MHz, CDCl3): d = 4.70 (s, 6 H).
13C NMR (75 MHz, CDCl3): d = 33.5 (NCH2), 44.8 (CBr), 72.8 (C),
147.1 (C=O).
1H NMR (300 MHz, CDCl3): d = 2.30 (t, J = 2.4 Hz, 1 H), 3.62–
3.89 (m, 2 H), 4.07 (d, J = 2.4 Hz, 2 H), 4.33–4.38 (m, 2 H).
13C NMR (75 MHz, CDCl3): d = 34.0 (NCH2), 43.8 (NCH2), 61.9
(OCH2), 73.3 (CH), 76.81 (C), 157.8 (C=O).
MS (ESI): m/z (%) = 477.9 (29), 479.9 (100), 482.0 (95), 483.9 (27)
[M + H]+.
Anal. Calcd for C6H7NO2: C, 57.59; H, 5.64; N, 11.19. Found: C,
57.77; H, 5.44; N,11.35.
Anal. Calcd for C12H6Br3N3O3: C, 30.03; H, 1.26; Br, 49.95; N,
8.76. Found: C, 30.16; H, 1.34; Br, 49.77; N, 8.81.
Bromination Reaction; General Procedure
1,3,5-Tris(6-bromo-3-oxahexa-5-ynyl)-1,3,5-triazinane-2,4,6-
trione (9b)
Following the general procedure with purification by column chro-
matography (silica gel, toluene–acetone, 4:1); white solid (73%);
Rf = 0.56 (toluene–acetone, 4:1).
1H NMR (300 MHz, CDCl3): d = 3.77 (t, J = 4.2 Hz, 6 H), 4.13 (t,
J = 4.2 Hz, 6 H), 4.20 (s, 6 H).
NBS (34.6 mmol) and AgNO3 (4.9 mmol) were added to a soln of
cyanurates 2 (3.3 mmol) or isocyanurates 3 (3.3 mmol) in degassed
acetone (75 mL) under stirring at r.t. under an argon atmosphere.
The mixture was stirred at r.t. overnight, extracted with CH2Cl2, and
washed with brine. The oily crude product was purified by column
chromatography (silica gel, toluene–acetone).
13C NMR (75 MHz, CDCl3): d = 41.8 (NCH2), 46.3 (CBr), 58.9
2,4,6-Tris(3-bromoprop-2-ynyloxy)-1,3,5-triazine (8a)
Following the general procedure with purification by column chro-
matography (silica gel, toluene–acetone, 20:1); white solid (36%);
mp 94–95 °C; Rf = 0.7 (toluene–acetone, 20:1).
1H NMR (300 MHz, CDCl3): d = 5.05 (s, 6 H).
13C NMR (75 MHz, CDCl3): d = 48.5 (CBr), 56.7 (CH2), 73.3 (C),
172.3 (CO).
(OCH2), 66.1 (CH2), 75.9 (C), 148.9 (C=O).
MS (ESI): m/z (%) = 610.0 (37), 611.9 (96), 613.9 (100), 615.9 (34)
([M + H]+).
Anal. Calcd for C18H18Br3N3O6: C, 35.32; H, 2.96; Br, 39.16; N,
6.87. Found: C, 35.40; H, 3.09; Br, 39.02; N, 6.73.
MS (ESI): m/z (%) = 477.9 (33), 479.9 (100), 481.8 (99), 483.8 (35)
Acknowledgment
([M + H]+).
We are grateful to Professor Jürgen Liebscher from Humboldt Uni-
versity, Berlin for fruitful discussions. We acknowledge the finan-
cial support of this work by PNCDI II program (UEFISCSU;
projects IDEAS 570/2007 and 2358/2008 and TD82).
Anal. Calcd for C12H6Br3N3O3: C, 30.03; H, 1.26; Br, 49.95; N,
8.76. Found: C, 30.27; H, 1.42; Br, 50.15; N, 8.64.
2,4,6-Tris(6-bromo-3-oxahexa-5-ynyloxy)-1,3,5-triazine (8b)
Following the general procedure with purification by column chro-
matography (silica gel, toluene–acetone, 9:1); white solid (36%);
mp 103–105 °C; Rf = 0.7 (toluene–acetone, 9:1).
Synthesis 2010, No. 10, 1639–1644 © Thieme Stuttgart · New York

1644
F. Piron et al.
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