Efficient synthesis of 19-31 membered macrocyclic tetralactones via ring closing metathesis in ionic liquids

Article abstract of DOI:10.1016/j.tet.2010.08.019

The ring closing metathesis reaction in the presence of Grubbs catalyst was demonstrated using several ionic liquids to synthesize a range of macrocyclic tetralactones having ring size of 19 to 31 membered with different spacers. The ionic liquid [mmim][PF₆] was found to be an excellent solvent and the recovery of the catalyst was demonstrated. X-ray analysis of a representative macrocyclic tetralactone was also reported.

Full text of DOI:10.1016/j.tet.2010.08.019

Tetrahedron 66 (2010) 8196e8202
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Efficient synthesis of 19e31 membered macrocyclic tetralactones via ring closing
metathesis in ionic liquids
*
Sengodagounder Muthusamy , Datschnamoorthy Azhagan
School of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 July 2010
Received in revised form 27 July 2010
Accepted 8 August 2010
Available online 18 August 2010
The ring closing metathesis reaction in the presence of Grubbs catalyst was demonstrated using several
ionic liquids to synthesize a range of macrocyclic tetralactones having ring size of 19 to 31 membered
with different spacers. The ionic liquid [mmim][PF6] was found to be an excellent solvent and the
recovery of the catalyst was demonstrated. X-ray analysis of a representative macrocyclic tetralactone
was also reported.
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
Grubbs catalyst
Ionic liquids
Ring closing metathesis
Macrocyclic tetralactones
1. Introduction
PCy3
MesN
NMes
MesN
NMes
Cl
Cl
During the past decade, ring closing metathesis (RCM) has found
increasing application in the synthesis of carbo- and heterocyclic
ring systems.1 The application of RCM as the key macrocyclization
step in the synthesis of crown compounds has opened their
importance in supramolecular chemistry.2e6 The success of this
reaction has been mainly due to the availability of Grubbs7 (1e3)
and Hoveyda8 (4,5) catalysts (Fig. 1). But these catalysts are not
recyclable and can only be separated via repeated chromatography
severely hampers their application. Several reports have recently
demonstrated the solutions for this problem. The methods rely on
the removal of ruthenium complexes by exchange of their hydro-
phobic with hydrophilic ligands followed by aqueous extraction,9
catalyst immobilization10 or on removal of the catalyst by treat-
ment with Pb(OAc)4,11 Ph3PO or DMSO.12
Ru
Cl
Cl
Ru
Pcy3
2
Ru
Pcy3
3
Cl
Cl
Ph
Pcy3
Ph
Ph
1
PCy3
Ru
MesN
NMes
Cl
Cl
Cl
Cl
Ru
O
O
4
5
Environmental concern associated with chemical synthesis has
posed demands for environmentally benign reaction has become
one of the main themes of modern synthesis. Towards this, ionic
liquids helped as an environmentally friendly alternative for con-
ventional organic solvents and gained much attention. Ionic liquids
are known to be nonvolatile, nontoxic, reusable and compatible
with many organic reactions. Our specific interest in ionic liquid
was drawn by the recent disclosures that ionic liquid (IL) stabilizes
Figure 1.
many organometallic catalysts and helps for the catalyst
recyclablity.13
Moreover, synthesis14 and studies15 of macrocyclic dilactones
are impressive in organic chemistry due to their biological prop-
erties, complex formation, ion carriers and application in perfume
industry. Even though literature methods provide a mixture of
dilactones and tetralactones, the reactions give low yields and
require drastic conditions. In continuation of our recent work16 on
the synthesis of macrocyclic tetralactones, we herein report a RCM
reaction in the presence of Grubbs’ catalyst to synthesize a variety
* Corresponding author. Tel.: þ91 431 2407053; fax: þ91 431 2407045; e-mail
address: muthu@bdu.ac.in (S. Muthusamy).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.08.019

S. Muthusamy, D. Azhagan / Tetrahedron 66 (2010) 8196e8202
8197
macrocyclic tetralactones using ionic liquid in good yields with
recyclability of the catalyst.
difficult task. The reaction mixture containing E/Z isomers was kept
to obtain a good crystal using ethyl alcohol as solvent. The major
isomer of 10a was crystallized and characterized as an E-isomer by
the X-ray crystallography (Fig. 3). To exploit this interesting result,
the diolefinic compounds 9bee, prepared from phthalic anhydride
system, was subjected to RCM reaction using 5 mol % of 1 to afford
the corresponding tetralactones 10bee as a mixture of E/Z isomers
in the ratio of 3:1. The RCM reaction of diolefin 9f that was obtained
from hexahydro-4-methylphthalic anhydride, furnished the re-
spective tetralactone 10f as a 2:1 mixture of E/Z isomers. The me-
tathesis reaction of diolefins 9geh that was derived from
cyclohexanedicarboxylic anhydride, yielded the respective tetra-
lactones 10geh as a 2:1 mixture of E/Z isomers. The metathesis
reaction of diolefins 10iel that was obtained from diphenic anhy-
dride, afforded the respective macrocyclic tetralactones 10iel as
a 3:1 mixture of E/Z isomers.
To study the RCM reaction of diolefinic compounds 9 in other
ionic liquids, a representative reaction of compound 9l was chosen.
Initial investigation of 9l was performed with ionic liquids having
different counter anions. Thus, the ionic liquids containing bmim,
bbim or mmim as counter cations and PF6, BF4, NO2 or HSO‑4das
counter anions were synthesized based on the literature.17 Reaction
of 9l using bmim ionic liquid having different counter anions in the
presence of 5 mol % of 1 at 60 ꢀC was performed to furnish the
corresponding macrocyclic compound 10l. The similar reaction of
9l with bbim ionic liquid having different counter anions furnished
the corresponding macrocyclic compound 10l. Reaction of 9l with
mmim ionic liquid having different counter anions also provided
the corresponding macrocycle 10l. The [mmim][PF6] ionic liquid is
found to be a good solvent and afforded the product 10l in high
yield. In turn, the ionic liquids having BF4, NO2-counter anions gave
poor yield and the results are depicted in Table 2. The ionic liquid
having HSO‑4 counter anion did not furnish any product.
2. Results and discussion
Initially, we planned to study the RCM in various imidazole
derivatives reported as ionic liquid medium. Towards this, we have
synthesized17 several ionic liquids for our present study (Fig. 2).
Based on the desymmetrization18 of anhydrides with alcohols, the
desymmetrization reactions of 2 equiv of cyclic anhydride 6 with
1 equiv of dihydroxy compound 7 in the presence of triethylamine
were performed to obtain the corresponding dicarboxylic acids
8ael. The dialkylation of 8ael with allyl bromide in the presence of
triethylamine afforded the corresponding diolefins 9ael with dif-
ferent spacers in good yield. The reaction of diolefin 9a in [mmim]
PF6 ionic liquid solution was carried out at 60 ꢀC in the presence of
Grubbs’ first generation catalyst 1 under an argon atmosphere to
furnish the crude reaction mixture. The purification by passing
through silica gel column chromatography afforded the 21-mem-
bered macrocyclic tetralactone 10a as a mixture of E/Z isomers in
95% yield (Scheme 1, Table 1, entry 1). The crude NMR spectrum
indicated that the product 10a obtained as a mixture of E/Z isomers
in the ratio of 3:1. 1H NMR spectrum showed the absence of ter-
minal olefinic CH2 hydrogens. Mass spectrum clearly indicated that
the molecular ion with a reduction of 28 atomic mass unit from the
starting material. To get a crystal for macrocycles is generally
Me
N
Bu
BF4
+
+
N
N
N
Me
Me
BF4
[mmim]BF4
[bmim]BF4
There are no considerable differences in the reaction rates and
yields by changing the substitution on the imidazole ring. The
efficiency of the ionic liquid was strongly influenced by the nature
of the anion. These results indicate that the anions play an impor-
tant role in RCM reaction. In order to compare, the reaction of 9l
was carried out using organic solvents, such as dichloromethane,
dichloroethane or toluene to afford the corresponding macrocyclic
compound 10l in moderate yield.
Me
Bu
+
+
N
N
N
N
Me
Me
PF6
PF6
[mmim]PF6
[bmim]PF6
To study the template effect involved in the preparation of
macrocycles, reaction of 9l using ionic liquid or organic solvent was
repeated in the presence of catalytic amount of 1 and CsCl under
similar reaction conditions to furnish the macrocycle 10l (Table 2).
The minor effect in the presence of CsCl was observed.
To study the recovery and recycling of the expensive Grubbs’
catalyst in line with the literature,19 the reaction of 9a was studied
for the recovery of catalyst 1 with different temperatures for the
duration of 10 h to optimize the reaction condition. The optimum
temperature is found to be 60 ꢀC for the RCM reactions using ionic
liquids. The yield of the product 10a was getting reduced when the
reaction was performed above or below 60 ꢀC during the recycling
process (Table 3). The reason might be the thermal decomposition
of 1 occurred at higher temperature.
Figure 2.
Y
O
O
O
O
O
O
O
NEt3
Y
X
O
+
X
X
HO
OH
DCM
0-5 °C
O
6
OH HO
8a-l
7
2 equiv
1 equiv
75-90%
allyl bromide
K2CO3, TBAI
DMF, rt
Finally, the representative reaction of diolefin 9a in the presence
of catalyst 1 using mmim[PF6] at 60 ꢀC was performed. The pink
coloured reaction mixture was extracted with dry ethyl acetate/
hexane (1:9) solution after the appropriate time duration to pro-
vide the product 10a free from Grubbs’ catalyst. The recovered pink
coloured ionic liquid containing the catalyst 1 was dried under
reduced pressure before performing the next reaction. The above
reaction was repeated by adding the required starting material 9a
to provide the corresponding product 10a. Notably, this process
was repeated five times and the yields are provided in Table 4. The
insolubility of ionic liquid in ethyl acetate/hexane (1:9) solution
O
X
O
X
1, CsCl
O
O
O
O
O
O
O
O
Ionic
X
X
Liquid
O
O
O
O
Y
O
O
Y
10a-l; 85-95%
9a-l; 85-90%
Scheme 1. Synthesis of macrocyclic tetralactones 10.

8198
S. Muthusamy, D. Azhagan / Tetrahedron 66 (2010) 8196e8202
Table 1
Synthesis of macrocyclic tetralactones 10 from diolefins 9 in the presence of Grubbs catalyst 1 using ionic liquid
b
Entry
Diolefins 9
Macrocyclic Tetralactones 10
Time (hours)
Ring Size
Yield (%)a
E/Z
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
1
11
21
95
3:1
O
10a
9a
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
2
11
19
94
3:1
10b
9b
O
O
O
O
O
O
3
9
20
92
3:1
O
O
O
O
O
O
O
O
O
O
10c
9c
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
4
9
22
90
3:1
10d
9d
O
O
O
O
O
O
O
O
O
O
5
9
24
94
3:1
O
O
O
O
O
O
O
O
O
O
O
O
10e
9e
O
O
O
O
O
O
H
H
H
H
H
O
O
O
O
6
8
21
86
2:1
O
O
O
O
H
H
H
O
O
10f
9f
O
O
O
O
O
O
O
O
H
H
H
H
H
H
H
O
O
O
O
O
O
O
O
7
8
19
85
2:1
H
10g
9g

S. Muthusamy, D. Azhagan / Tetrahedron 66 (2010) 8196e8202
8199
b
Table 1 (continued)
Entry
Diolefins 9
Macrocyclic Tetralactones 10
Time (hours)
Ring Size
Yield (%)a
E/Z
O
O
O
O
O
O
O
O
O
O
H
H
H
H
H
H
H
H
O
O
O
O
O
O
O
O
8
8
21
87
2:1
O
10h
9h
O
O
O
O
O
O
O
O
O
O
O
O
9
8
23
92
3:1
O
O
O
10i
9i
O
O
O
O
O
O
O
O
O
O
O
O
O
O
10
8
25
93
3:1
O
O
10j
9j
O
O
O
O
O
O
O
O
O
O
O
O
11
8
28
95
3:1
O
O
O
O
10k
9k
O
O
O
O
O
O
O
O
O
O
O
O
O
12
8
31
93
3:1
O
O
O
O
O
O
O
O
O
10l
9l
a
Yields (unoptimized) refer to isolated pure compounds of macrocyclic tetralactones 10.
Ratio of isomers is determined by proton NMR spectroscopy.
b
and the very good solubility of Grubbs’ catalyst in ionic liquid
helped to productively recycle the catalyst. Based on this process,
Grubbs’ catalyst 1 could be immobilized in [mmim]PF6 while per-
forming the above RCM reaction. It is noteworthy to mention that
the recovery of the catalyst 1 at 60 ꢀC in ionic liquid was very good
during recycling process rather it was observed as low.19
3. Conclusion
In conclusion, we have described the synthesis of various di-
olefins and their ring closing metathesis reaction was demon-
strated to synthesize a range of macrocyclic tetralactones in several
ionic liquids. The ionic liquid [mmim][PF6] is an excellent solvent to
synthesize macrocyclic tetralactones via RCM and the recovery of
Figure 3. ORTEP view of compound 10a.

8200
S. Muthusamy, D. Azhagan / Tetrahedron 66 (2010) 8196e8202
Table 2
performed on silica and components were visualized by observation
under iodine, UV-light or sulfuric acid charring. Column chroma-
Reaction of 9l at 60 ꢀC with various ionic liquid or solvent
tography was performed on a silica gel (100e200 mesh) column.
Entry
Ionic liquid or Solvent
Time (min)
Yield (%) of 10l
Without CsCla
With CsCla
4.2. General experimental procedure for the synthesis of
macrocycle 10
1
2
3
4
5
6
7
8
[bmim][PF6]
[bmim][BF4]
[bmim][NO3]
[bmim][HSO4]
[bbim][PF6]
[bbim][BF4]
[bbim][NO3]
[mmim][BF4]
[mmim][PF6]
[mmim][NO3]
DCM
8
24
24
24
8
24
24
24
8
24
24
24
24
85
53
20
d
87
56
22
d
The bis-olefin 9 (1.0 mmol) was taken in a well-dried ionic liquid
(3.0 mL) under an argon atmosphere. The reaction mixture was
stirred at room temperature for 5 min to obtain a clear oily solution.
To this ionic liquid solution, 5 mol % of Grubbs’ first generation
catalyst and CsCl was added stirred at 60 ꢀC for 8e12 h. The re-
action was followed by TLC and 1H NMR. After completion of the
reaction, the crude reaction mixture was washed with 10% dry ethyl
acetate in hexane (5ꢁ10 mL) till the absence of any organic com-
pound in the solvent layer. The combined extracts were concen-
trated in vacuum and the resulting residue subjected on
a 100e200 mesh silica gel column chromatography to afford the
macrocycle 10. The ionic liquid layer was dried on the vacuum line
to use the next cycles during the recycling process.
86
56
18
59
90
21
68
65
72
89
60
21
61
93
26
90
89
86
9
10
11
12
13
DCE
Toluene
a
Yields (unoptimized) refer to isolated pure compound 10l.
Table 3
Studies on the reuse of catalyst 1 and temperature effect on 9a
Entry
Temperature
Cycles, Yield of 10a (%)a
4.2.1. Compound 10a. A white solid; mp 144e146; nmax (neat) 3022,
I
II
III
IV
1725, 1435, 1281, 1116, 738, 668 cmꢂ1
; dH (400 MHz, CDCl3)
1
2
3
4
5
25
40
60
80
100
20
74
93
93
93
17
68
88
87
85
13
63
84
80
65
7
57
80
77
40
7.75e7.70 (4H, m, AreH), 7.57e7.53 (4H, m, AreH), 6.03e6.02 (2H,
m, ]CH), 4.85e4.84 (4H, m, OCH2), 4.47e4.41 (4H, m, OCH2),
3.79e3.77 (4H, m, OCH2); dC (100 MHz, CDCl3) 167.7 (C]O), 167.2
(C]O),131.9 (CAr),131.7 (CAr),131.6 (CAr),131.2 (]CH),131.1 (]CH),
129.1 (]CH2),129.0 (]CH),128.8 (]CH),128.5 (]CH),128.2 (]CH),
127.9 (]CH), 68.8 (OCH2), 65.0 (OCH2), 61.2 (OCH2); HRMS (ESIþ)
calcd for C24H22O9 [MþNa]þ: 477.1162 found 477.1154.
a
Yields (unoptimized) refer to isolated pure compounds 10a.
Table 4
Studies on the reuse of catalyst 1 and (mmim)(PF6) on 9aa
Crystal data for the compound 10a (CCDC 783915): C24H22O9,
M¼454.42, 0.20ꢁ0.20ꢁ0.16 mm, Monoclinic, space group P-21 with
Entry
Yield of 10a (%)b
Recovered ionic liquid
a¼7.182 (10) Å, b¼8.495 (10) Å, c¼17.763 (3) Å,
a
¼90ꢀ,
b
¼98.684 (10)ꢀ,
g
¼90ꢀ, V¼1071.48 (3) Å3, T¼293(2) K, R1¼0.1016, wR2¼0.3972 on ob-
1
2
3
4
5
93
88
84
80
76
99
99
97
96
96
served data, z¼2, Dcalcd¼1.355 mg cmꢂ3, F(000)¼532, Absorption coef-
ficient¼0.095 mmꢂ1
¼0.71073 Å, 5906 reflections were collected on
,
l
a smart apex CCD single crystal diffractometer 3669 observed reflections
(Iꢃ2
s
(I)). The largest difference peak and hole¼0.985 and ꢂ0.495 e Åꢂ3
,
a
All reactions were carried out at 60 ꢀC.
Yields (unoptimized) refer to isolated pure compounds 10a.
respectively. The structure was solved by direct methods and refined by
b
full-matrix least squares on F2 using SHELXLe97 software.
the catalyst was also demonstrated. Most importantly, the process
is friendly to the environment to synthesize various macrocyclic
tetralactones having ring size of 19e31 membered with different
spacers. These macrocyclic compounds are expected to be poten-
tially important to the biologically significant materials and su-
pramolecular chemistry.
4.2.2. Compound 10b. A white solid; mp 123e125; nmax (neat)
2935, 1714, 1597, 1387, 1291, 1135, 1073, 744 cmꢂ1
; dH (400 MHz,
CDCl3) 7.80e7.74 (4H, m, AreH), 7.73e7.74 (4H, m, AreH),
6.03e6.02 (2H, m, ]CH), 4.97e4.96 (4H, m, ]CH2), 4.41 (4H, t,
OCH2, J 6 Hz), 2.20e2.14 (2H, m, CH2); dC (100 MHz, CDCl3) 167.7
(C]O), 167.1 (C]O), 132.3 (CAr), 131.4 (]CH), 131.2 (CAr), 129.4
(]CH), 128.9 (]CH), 127.9 (]CH), 127.8 (]CH), 64.9 (OCH2), 62.7
(OCH2), 62.5 (OCH2), 61.4 (OCH2), 28.0 (CH2); HRMS (ESIþ) calcd for
C23H20O8 [MþNa]þ: 447.1056 found 447.1068.
4. Experimental section
4.1. General
4.2.3. Compound 10c. A white solid; mp 149e151; nmax (neat) 3037,
All reactions were carried out in oven-dried glassware under an
atmosphere of argon. All solvents were freshly purified by distilla-
tion. IR spectra were recorded neat on a Bruker Alpha FT-IR spec-
trophotometer. 1H NMR and 13C NMR spectra were recorded (400
and 100 MHz, respectively) on a Bruker Avance DPX 400 using
CDCl3. Chemical shifts for proton and carbon resonances are repor-
2930, 1720, 1599, 1448, 1283, 1138, 1034, 748 cmꢂ1
; dH (400 MHz,
CDCl3) 7.73e7.64 (4H, m, AreH), 7.58e7.570 (4H, m, AreH),
7.49e7.65 (2H, m, AreH), 7.39e7.28 (2H, m, AreH), 5.84e5.83 (2H,
m, ]CH2), 5.79e5.78 (4H, m, CH2), 4.52 (4H, d, OCH2 J 4 Hz); dC
(100 MHz, CDCl3) 167.7 (C]O), 167.3 (C]O), 167.2 (C]O), 166.9
(C]O), 134.3 (CAr), 133.8 (CAr), 132.5 (CAr), 131.6 (CAr), 131.5 (CAr),
131.5 (]CH), 131.3 (]CH), 131.0 (]CH), 130.8 (CAr), 129.8 (]CH),
129.3 (]CH),129.2 (]CH), 129.0 (]CH),129.0 (]CH),128.9 (]CH),
128.6 (]CH), 128.1 (]CH), 127.5 (]CH), 65.0 (OCH2), 64.9 (OCH2),
64.7 (OCH2), 61.1 (OCH2); HRMS (ESIþ) calcd for C28H22O8 [MþNa]þ:
509.1212 found 509.1221.
ted for the major isomer in parts per million (
d) relative to tetra-
methylsilane 0.00) and chloroform
(
d
(d 77), respectively.
Multiplicities are indicated by singlet (s), doublet (d), triplet (t),
quartet (q), multiplet (m). Coupling constants (J) were reported in
hertz (Hz). Carbon types were determined from 13C NMR and DEPT
experiments. High resolution mass analyses were performed using
electrospray ionization (ESI) technique on a Waters QTof-micro
mass spectrometer. Analytical thin layer chromatography (TLC) was
4.2.4. Compound 10d. A white solid; mp 153e155; nmax (neat),
3066, 2935, 1715, 1597, 1387, 1292, 1135, 1073, 742 cmꢂ1
; dH

S. Muthusamy, D. Azhagan / Tetrahedron 66 (2010) 8196e8202
8201
(400 MHz, CDCl3) 7.68e7.63 (4H, m, AreH), 7.49e7.43 (4H, m,
AreH), 5.94e5.94 (2H, m, ]CH), 4.76 (4H, q, ]CH2, J 4 Hz),
4.24e4.20 (4H, m, OCH2), 1.66e1.59 (4H, m, CH2), 1.32e1.29 (4H, m,
CH2); dC (100 MHz, CDCl3) 167.9 (C]O), 167.1 (C]O), 132.7 (CAr),
132.6 (CAr), 131.4 (]CH), 129.9 (CAr), 127.0 (]CH), 128.1 (]CH)
65.8 (OCH2), 65.1 (OCH2), 61.1 (CH2), 32.6 (CH2), 28.8 (CH2), 28.6
(CH2), 28.3 (CH2), 25.6 (CH2); HRMS (ESIþ) calcd for C26H26O8
[MþNa]þ: 489.1525 found 489.1537.
61.1 (OCH2), 60.9 (OCH2), 27.4 (CH2); HRMS (ESIþ) calcd for
C35H28O8 [MþNa]þ: 599.1682, found 599.1699.
4.2.10. Compound 10j. Semisolid; nmax (neat) 3132, 3082, 2027,
1724, 1577, 1280, 754 cmꢂ1
; dH (400 MHz, CDCl3) 7.96e7.93 (2H, m,
AreH), 7.87e7.85 (2H, m, AreH), 7.45e7.40 (4H, m, AreH),
7.35e7.29 (4H, m, AreH), 7.17e6.96 (8H, m, AreH), 5.35e5.34 (2H,
m, ]CH), 4.97e4.87 (4H, m, CH2), 4.32e4.14 (4H, m, OCH2); dC
(100 MHz, CDCl3) 166.9 (C]O), 166.8 (C]O), 166.7 (C]O), 166.6
(C]O), 143.2 (CAr), 143.1 (CAr), 131.6 (CAr), 131.5 (]CH), 131.2
(]CH), 130.4 (]CH), 130.2 (]CH), 130.2 (]CH), 130.0 (]CH), 129.9
(]CH2), 129.8 (]CH2), 128.6 (]CH), 128.5 (]CH), 128.3 (]CH),
127.7 (]CH), 127.6 (]CH), 127.2 (]CH), 64.4 (OCH2), 64.0 (OCH2),
63.9 (OCH2), 59.8 (OCH2), 59.6 (OCH2); HRMS (ESIþ) calcd for
C40H30O8 [MþNa]þ: 661.1838, found 661.1851.
4.2.5. Compound 10e. A white solid; mp 137e139; nmax (neat) 2951,
2887, 1728, 1448, 1281, 1124, 1078, 738 cmꢂ1
; dH (400 MHz, CDCl3)
7.78e7.70 (4H, m, AreH), 7.59e7.52 (4H, m, AreH), 6.09e6.06 (2H,
m, ]CH), 4.89e4.84 (4H, m, OCH2), 4.41e4.36 (4H, m, OCH2),
3.76e3.64 (8H, m, OCH2); dC (100 MHz, CDCl3) 167.7 (C]O), 167.1
(C]O), 131.6 (CAr), 131.2 (]CH), 131.1 (]CH), 130.0 (]CH), 128.6
(]CH), 125.1 (CAr), 70.6 (OCH2), 68.9 (OCH2), 65.2 (OCH2), 64.9
(OCH2); HRMS (ESIþ) calcd for C26H26O10Na [MþNa]þ: 521.1424,
found 521.1411.
4.2.11. Compound 10k. Semisolid; nmax (neat) 3132, 3082, 2027,
1724, 1577, 1280, 754 cmꢂ1
; dH (400 MHz, CDCl3) 7.94e7.88 (4H, m,
AreH), 7.45e7.30 (8H, m, AreH), 7.14e7.09 (4H, m, AreH),
5.24e5.22 (2H, m, ]CH), 4.40e4.30 (4H, m, OCH2), 3.89 (4H, t,
OCH2, J 6 Hz), 1.22e1.01 (12H, m, CH2); dC (100 MHz, CDCl3) 171.2
(C]O), 167.2 (C]O), 166.6 (C]O), 166.5 (C]O), 143.5 (CAr), 143.4
(CAr), 131.5 (]CH), 131.4 (]CH), 131.3 (]CH), 130.2 (]CH), 129.9
(]CH), 129.7 (]CH) 129.3 (]CH2), 127.4 (]CH), 127.1 (]CH), 64.9
(OCH2), 62.8 (OCH2), 60.4 (OCH2), 60.0 (OCH2), 32.6 (CH2), 29.2
(CH2), 29.1 (CH2), 28.9 (CH2), 28.2 (CH2), 28.1 (CH2), 25.7 (CH2), 25.6
(CH2); HRMS (ESIþ) calcd for C40H38O8 [MþNa]þ: 669.2464, found
669.2453.
4.2.6. Compound 10f. Semisolid; nmax (neat) 3030, 2925, 1729,
1440, 1372, 1295, 1185, 1033, 936 cmꢂ1
; dH (400 MHz, CDCl3)
7.26e7.19 (4H, m, AreH), 5.56e5.55 (2H, m, ]CH), 5.17e4.85
(4H, m, ]CH2), 4.42 (4H, s, CH2,) 3.22e3.20 (4H, m, OCH2),
2.47e2.12 (2H, m, CH2), 1.98e1.95 (2H, m, CH), 1.72e1.71 (4H, m,
CH), 1.48e1.11 (8H, m, CH2), 0.88 (6H, s, CH3); dC (100 MHz,
CDCl3) 173.4 (C]O), 173.0 (C]O), 173.0 (C]O), 172.0 (C]O).
136.3 (CAr), 136.2 (CAr), 128.6 (]CH2), 128.2 (]CH2), 127.8
(]CH2), 127.7 (]CH2), 127.6 (]CH2), 127.5 (]CH2), 127.4
(]CH2), 127.3 (]CH2), 66.0 (OCH2), 65.9 (OCH2), 63.7 (OCH2),
43.7 (CH), 43.5 (CH), 43.2 (CH), 43.2 (CH), 41.9 (CH), 41.8 (CH),
41.7 (CH), 41.2 (CH), 36.3 (CH2), 33.8 (CH2), 28.0 (CH2), 24.1
(CH3), 22.3 (CH3); HRMS (ESIþ) calcd for C30H38O8Na [MþNa]þ:
549.2464, found 549.2470.
4.2.12. Compound 10l. Semisolid; nmax (neat) 3132, 3082, 2027,
1724, 1577, 1280, 754 cmꢂ1
; dH (400 MHz, CDCl3) 7.94e7.88 (4H, m,
AreH), 7.45e7.30 (8H, m, AreH), 7.14e7.09 (4H, m, AreH),
5.25e5.23 (2H, m, ]CH), 4.89e4.84 (4H, m, OCH2), 4.41e4.36 (4H,
m, OCH2), 3.76e3.64 (12H, m, OCH2); dC (100 MHz, CDCl3) 171.3
(C]O), 167.1 (C]O), 166.6 (C]O), 166.5 (C]O), 143.4 (CAr), 143.5
(CAr), 131.5 (]CH), 131.4 (]CH), 131.3 (]CH), 130.2 (]CH), 129.9
(]CH), 129.7 (]CH) 129.3 (]CH2), 127.4 (]CH), 127.1 (]CH), 70.6
(OCH2), 68.9 (OCH2), 65.2 (OCH2), 64.9 (OCH2), 64.1 (OCH2), 62.8
(OCH2), 60.4 (OCH2), 60.0 (OCH2); HRMS (ESIþ) calcd for
C40H38O11Na [MþNa]þ: 717.2312, found 717.2325.
4.2.7. Compound 10g. Semisolid; nmax (neat) 3132, 3082, 2027,
1724, 1574, 1280, 754 cmꢂ1
; dH (400 MHz, CDCl3) 5.74e5.73 (2H, m,
]CH), 5.61 (4H, s, ]CH), 4.65e4.43 (2H, m, CH2), 4.22e4.19 (2H, m,
OCH2), 4.07e4.00 (4H, m, OCH2), 3.06e3.00 (4H, m, OCH),
2.46e2.27 (8H, m, CH2), 1.87e1.84 (2H, m, CH2); dC (100 MHz,
CDCl3) 172.7 (C]O), 172.7 (C]O), 172.6 (C]O), 172.6 (C]O), 128.0
(]CH), 127.9 (]CH), 127.6 (]CH), 127.6 (]CH), 127.6 (]CH), 63.9
(OCH2), 61.4 (OCH2), 61.3 (OCH2), 39.9 (CH), 39.8 (CH), 28.2 (CH2),
28.1 (OCH2), 27.9 (CH2), 25.7 (CH2); HRMS (ESIþ) calcd for C23H28O8
[MþNa]þ: 455.1682, found 455.1670.
Acknowledgements
This research was supported by the Ministry of Environment
and Forests, New Delhi. We thank DST, New Delhi for providing
400 MHz NMR facility under FIST program.
4.2.8. Compound 10h. Colourless thick oil; nmax (neat) 3031,
2894, 1732, 1440, 1351, 1297, 1192, 1250, 736 cmꢂ1
; dH (400 MHz,
CDCl3) 5.86e5.79 (2H, m, ]CH), 5.68 (4H, s, ]CH), 4.79e4.50
(4H, m, OCH2), 4.38e4.07 (4H, m, OCH2), 3.65 (4H, t, OCH2, J
5 Hz), 3.12e3.06 (4H, m, CH), 2.57e2.31 (8H, m, CH2); dC
(100 MHz, CDCl3) 172.8 (C]O), 172.7 (C]O), 172.6 (C]O), 172.6
(C]O), 128.3 (]CH), 127.8 (]CH), 127.7 (]CH), 124.9 (]CH),
68.7 (OCH2), 63.9 (OCH2), 63.6 (OCH2), 63.5 (OCH2), 60.1 (OCH2),
39.9 (CH), 39.7 (CH), 25.7 (CH2), 25.6 (CH2), 25.5 (CH2), 25.3
(CH2); HRMS (ESIþ) calcd for C24H30O9 [MþNa]þ: 485.1788,
found 485.1778.
Supplementary data
Supplementary data associated with this article can be found in
the online version at doi:10.1016/j.tet.2010.08.019.
References and notes
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