Selective transformation of tricyclic peroxides with pronounced antischistosomal activity into 2-hydroxy-1,5-diketones using iron (II) salts

Article abstract of DOI:10.1016/j.tet.2016.04.054

The present work deals with selective transformations of peroxides into organic compounds via the cleavage of the O-O bond using variable valence metals. A selective transformation of tricyclic peroxides promoted by Fe²⁺ salts was discovered. T

Full text of DOI:10.1016/j.tet.2016.04.054

Tetrahedron xxx (2016) 1e6
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Selective transformation of tricyclic peroxides with pronounced
antischistosomal activity into 2-hydroxy-1,5-diketones using iron
(II) salts
,
a,
Alexander O. Terent’ev a , Zhanna Yu. Pastukhova b, Ivan A. Yaremenko a,
*
Roman A. Novikova, Dmitry V. Demchuk a, Lev G. Bruk a b, Dmitry O. Levitsky c,
,
Fabrice Fleuryc, Gennady I. Nikishin a
a N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991, Moscow, Russian Federation
b Lomonosov Moscow University of Fine Chemical Technology, 86 prosp. Vernadskogo, 119571, Moscow, Russian Federation
c
ꢀ
ꢁ
UFIP CNRS UMR 6286, Mechanism and regulation of DNA repair team Universite de Nantes, 2 rue de la Houssiniere, 44322, France
a r t i c l e i n f o
a b s t r a c t
Article history:
The present work deals with selective transformations of peroxides into organic compounds via the
cleavage of the OeO bond using variable valence metals. A selective transformation of tricyclic peroxides
promoted by Fe2þ salts was discovered. This selective transformation is unexpected for compounds with
structural features which allow diverse decomposition pathways. 2-Hydroxy-1,5-diketones are prepared
in yields up to 92% in the reactions of tricyclic peroxides with FeSO4, Fe(ClO4)2, or FeCl2. This is a new
preparative method for the synthesis of 1,5-diketones. 2-Hydroxy-1,5-diketones in CDCl3 at 25 ꢀC exist
mainly in the open-chain form of the hydroxyketone over the cyclic hemiacetal. The results of this work
can be of interest to understand the mechanism of the antiparasitic action of peroxides.
Ó 2016 Elsevier Ltd. All rights reserved.
Received 27 January 2016
Received in revised form 3 April 2016
Accepted 21 April 2016
Available online xxx
Keywords:
Peroxides
Diketones
Cycles
Iron (II) salts
Antiparasitic
1. Introduction
a limited number of examples of the preparative application of
peroxide cleavage by such salts.
The chemistry of peroxides is of interest in organic synthesis
largely due to the potential of oxidative transformations associated
with a weak OeO bond, which can be cleaved via both homo- and
heterolytic mechanisms. The most well-known and commonly
used processes are reactions without the involvement of variable
valence metals: the synthesis of lactones by the BaeyereVilliger
oxidation,1 the Story synthesis of lactones,2 the Hock synthesis of
phenol and acetone,3 the Criegee cleavage of peresters,4 the
KornblumeDeLaMare rearrangement and related processes giving
carbonyl compounds and alcohols,5 the Schenck and Smith rear-
rangements of steroid hydroperoxides.6 Other oxidative trans-
formations of peroxides giving acids,7 esters,8 ketones,9 and
epoxides10 are also known. The present work deals with selective
transformations of peroxides into organic compounds via the
cleavage of OeO bond using variable valence metals. There are
For instance, the b-scission of cyclic ketone peroxides to form
omega-functionalized,11 unsaturated,12 and dicarboxylic acids,13
the formation of C-centered radicals from ketone peroxides and
their addition to alkenes14 and diazonium salts15 were docu-
mented. The cleavage of hydroperoxides promoted by metal salts
can be used to synthesize macrocycles,16,17 ketones,18 hal-
oketones,19 and diketones.20
The main problem with the metal salt-promoted cleavage of
peroxides is low selectivity of the reactions. In the present work, we
succeeded in finding a non-trivial example of reaction, in which
tricyclic monoperoxides21 are transformed into hydroxydiketones
in high yield under the action of iron ions. To the best of our
knowledge the discovered process is the first example of the oxi-
dative deacylation of b-diketones to afford a-hydroxylated ketones.
This transformation provides a facile approach to the preparation of
1,5-diketones. Selected methods of the synthesis of 1,5-diketones
are based mainly on the reaction of ketones with para-
formaldehyde,22 the Wacker-type oxidation of 1,6-dienes,23 the
oxidation of 1,6-alkynes,24 the reaction of glutaric acid chloride
* Corresponding author. Tel.: þ7 916 385 4080; e-mail address: terentev@ioc.ac.
ru (A.O. Terent’ev).
http://dx.doi.org/10.1016/j.tet.2016.04.054
0040-4020/Ó 2016 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Terent’ev, A. O.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.04.054

2
A.O. Terent’ev et al. / Tetrahedron xxx (2016) 1e6
with Grignard-25 and organolithium reagents,26 and the oxidation
of various compounds containing a cyclopentane ring.27
2,6-dione 2e from 3a-benzyl-3,6,7a-trimethyltetrahydro-3H,4H-
3,6-epoxy[1,2]-dioxolo[3,4-b]pyran 1e. For the reaction, we exam-
ined the effect of the nature of the catalyst, the reaction time, and
the addition of sulfuric acid on the yield of hydroxydiketone 2e
(Table 1).
It was found that the tricyclic monoperoxides studied in this
paper show pronounced antischistosomal activity.28 Schistosomi-
asis is a neglected tropical disease, caused basically by three
Schistosoma species, S. mansoni, S. haematobium, and S. japonicum.
Chemotherapy using praziquantel is the mainstay of control. Pra-
ziquantel is a broad-spectrum antischistosomal drug and the
treatment of choice since its discovery in the 1970s. Every year
millions of people are treated with praziquantel in the frame of
mass drug administration programs. For instance, in 2012, 27.5
million people in 21 countries were treated with praziquantel. In
2018, the World Health Organization aims to treat as many as 235
million people. The risk for praziquantel resistance or tolerance is
rising with increasing drug applications.29 These facts stimulate for
new antischistosomal drugs development.30
Table 1
Results of the optimization of the synthesis of 2e from tricyclic peroxide 1ea
Ph
O
Fe2+
CH3CN / H2O (3.5 / 1)
OH
O
O
O
Ph
O
O
1e
2e
Entry
Metal salt
Time, h
Yield of 2e, %
In recent years, various semisynthetic and synthetic peroxide
classes have been tested for antischistosomal properties.31 It is
proposed that a reaction of the peroxide moiety with ferrous iron in
heme is responsible for both the antischistosomal and antimalarial
activity.32 As a consequence of this iron-dependent antiparasitic
activity, the results of this work may be helpful for understanding
some steps of the biological mode of action of peroxides.
1
2b
3
4
5
6
7
8
FeSO4$7H2O
FeSO4$7H2O
FeSO4$7H2O
FeSO4$7H2O
Fe(ClO4)2$6H2O
FeCl2
1
1
3
24
1
1
84
92
85
85
90
88
55
40
Fe(acac)2
FeBr2
36
2
a
It is important to note that tricyclic monoperoxides could be
General reaction conditions: Peroxide 1e (300 mg, 1.09 mmol) was dissolved
in MeCN (7 mL), and the solution was added at 20e25 ꢀC to a solution of FeS-
O4$7H2O, Fe(ClO4)2$6H2O, FeCl2, Fe(acac)2, or FeBr2 (1.5 mol Fe2þ/1 mol 1e) in H2O
(2 mL).
easily prepared from hydrogen peroxide and
b
,
d
-triketones, which
are the products of Michael addition of
b-diketones to vinyl ketones
(Scheme 1).21
b
H2SO4 (0.2 g, 1.99 mmol) was additionally added to a solution of FeSO4$7H2O in
H2O.
The best results were obtained in runs 1e6 (Table 1) using a 1.5-
fold molar excess of FeSO4$7H2O, Fe(ClO4)2$6H2O, or FeCl2. Dike-
tone 2e was obtained in the highest yield in run 2 in the presence of
H2SO4. The salts Fe(acac)2 and FeBr2 are less efficient in the syn-
thesis of diketone 2e (runs 7 and 8, respectively). The cleavage of
tricyclic peroxide 1e by other variable valence metal salts, such as
CuBr, CuBr2, CoBr2, Mn(OAc)3$2H2O, and Mn(OAc)2$4H2O, which
are often used in reactions with peroxides,33 did not produce target
diketone 2e. The results of runs 1e6 show that diketone 2e can be
obtained in good yield using a 1.5-fold molar excess of FeSO4 and in
the presence of sulfuric acid (run 2). Under the conditions of run 2
(Table 1), we synthesized a series of hydroxydiketones 2aeh con-
taining various functional groups: cyano group (2d), nitro group
(2g), or aromatic rings 2eeh (Table 2).
Scheme 1. General approach to the synthesis of tricyclic peroxides.
2. Results and discussion
The treatment of tricyclic monoperoxides 1aeh with Fe2þ salts
resulted in the selective formation of 2-hydroxy-1,5-diketones
2aeh (Scheme 2).
The cleavage of monoperoxides 1aeh produced hydrox-
ydiketones 2aeh in yields from 28% to 92%. The best results were
obtained for hydroxydiketones 2beh containing a bulky sub-
stituent between the keto-groups. Hydroxydiketone 2a, without
R'
O
a substituent in a-position was obtained in lower yield.
OH
R''
O
Fe2+
O
R''
O
R'
O
O
2.1. Proposed mechanism of the transformation of tricyclic
monoperoxides
CH3CN / H2O
2a-h
1a-h
a: R' = H, R'' = CH3; b: R' = CH3, R'' = CH3;
The proposed mechanism of the formation of the target prod-
ucts (as exemplified by 2e) involves the oxidation of Fe2þ ions to
Fe3þ by peroxide 1e with two equivalent oxygen atoms in the
peroxide bridge to form the radical anion (A) as the first step, fol-
lowed by the rearrangement of A into the stabilized tertiary C-
c: R' = n-Bu, R'' = CH3; d: R' = CH2CH2CN, R'' = CH3;
e: R' = CH2Ph, R'' = CH3; f: R' = 4-MeC6H4CH2, R'' = CH3;
g: R' = 4-NO2C6H4CH2, R'' = CH3; h: R' = H, R'' = Ph
Scheme 2. Synthesis of 2-hydroxy-1,5-diketones 2aeh from tricyclic peroxides 1aeh
using iron salts.
centered radical (B) through characteristic for peroxides
b-
scission.11e13 The radical (B) is oxidized by Fe3þ to form the cation
(C), which is transformed into the intermediate (D) upon exposure
to water. Finally, hydrolysis of the two acetal moieties gives target
hydroxydiketone 2e (Scheme 3).
The transformation of peroxides was performed by treatment
with a series of iron salts, such as FeSO4$7H2O, Fe(ClO4)2$6H2O,
FeCl2, Fe(acac)2, and FeBr2, in aqueous acetonitrile, which ensures
the solubility of both tricyclic monoperoxide and inorganic salts.
The conditions for the synthesis of hydroxydiketones were opti-
mized by studying the preparation of 3-benzyl-3-hydroxyheptane-
Similar mechanisms were reported in the literature for the
cleavage of ketone peroxides to form omega-functionalized11 and
unsaturated12 acids.
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A.O. Terent’ev et al. / Tetrahedron xxx (2016) 1e6
3
Table 2
O
Structures and yields (%) of hydroxydiketones 2aeha
O
OH
R''
OH
O
R''
R'
R'
O
O
O
OH
OH
2a'-h'
2a-h
Scheme 4. Equilibrium between the linear form 2aeh and the cyclic form 2a0eh0.
O
O
2a, 28
2b, 63
diketone 2g. This is attributed to the fact that the bulky sub-
stituent favors the cyclization. The assignment of the signals cor-
responding to the structures that form an equilibrium mixture was
made based on the results of 2D NMR experiments (1H, 1H-COSY,
NOESY (EXSY) and 1H, 13C-HSQC, HMBC). The 1H NMR spectra of the
open forms of 2aeh show characteristic signals of acetyl groups at
O
OH
n-Bu
O
O
OH
O
NC
2c, 84
2d, 58
d
2.1e2.3 ppm and specific splitting of the signals of CH2eCH2
groups. The 13C NMR spectra exhibit a signal for the carbon atom of
the carbinol (COH) at 75.6e81.5 ppm. The NMR spectra of the
cyclic forms show characteristic signals of the methyl protons at
1.4e1.6 ppm (1H), as well as signals for the carbon atoms of
CH3C(O)CO at 91.4e91.9 ppm and signals for the hemiketal carbon
atom at
106.6e106.9 ppm (13C).
O
d
O
OH
OH
d
O
d
O
d
2e, 92
2f, 83
3. Conclusions
The selective transformation of tricyclic peroxides promoted by
Fe2þ salts was discovered. This selective transformation is un-
expected for compounds with structural features which allow di-
verse decomposition pathways. Tricyclic peroxides are transformed
into 2-hydroxy-1,5-diketones in yields up to 92% by the treatment
OH
O
O
OH
O
O
with FeSO4, Fe(ClO4)2, or FeCl2. Vinyl ketones and
b-diketones were
the starting compounds for -triketone syntheses, from which
b,d
tricyclic peroxides are prepared using hydrogen peroxide. To the
best of our knowledge we have found the first example of the ox-
2h, 83
NO2
2g, 75
idative deacylation of
b-diketones for the preparation of a-hy-
a
Peroxide 1aeh (300 mg, 0.94e1.61 mmol) was dissolved in MeCN (7 mL), and
the solution was added at 20e25 ꢀC to a solution of FeSO4$7H2O (392e673 mg,
1.41e2.42 mmol, 1.5 mol FeSO4$7H2O/1 mol 1aeh) in H2O (2 mL) containing H2SO4
(0.2 g, 1.99 mmol). The reaction mixture was stirred at 20e25 ꢀC for 1 h.
droxylated ketones. This work can be of interest to understand the
iron-dependent antiparasitic action of peroxides.
4. Experimental section
Caution: Although we have encountered no difficulties in
working with peroxides, precautions, such as the use of shields,
fume hoods, and the avoidance of heating and shaking, should
be taken whenever possible.
Ph
Ph
Ph
O
Fe3+
Fe2+
- Fe3+
H
O
OH
O
O
- Fe2+
O
O
O
O
O
O
O
NMR spectra were recorded on Bruker Avance II 300 and Bruker
Avance 400 instruments (300.13 and 400.13 MHz for 1H, 75.48 and
100.61 MHz for 13C in CDCl3 referenced to residual solvent signal
7.25 ppm for 1H and 77.0 ppm for 13C spectra). High-resolution
mass spectra were recorded on a Bruker micrOTOF instrument
equipped with an electrospray ionization (ESI) ion source.34 All
measurements were carried out in positive (þMS) ion mode (in-
terface capillary voltage e 4500 V) with the m/z scan range of
50e3000; the external/internal calibration was carried out with
Electrospray Calibrant Solution. A syringe injection was used for
1e
B
A
O
Ph
OH
Ph
HO
OH
H2O
- H
OH
Ph
O
O
O
O
O
O
O
2e
C
D
Scheme 3. Proposed mechanism of the formation of 2-hydroxy-1,5-diketones from
tricyclic monoperoxides by an example of the transformation of 1e into 2e promoted
by iron salts.
solutions in MeCN (flow rate 3 mL/min). Nitrogen was used as both
the nebulizer gas (0.4 bar) and the dry gas (4.0 L/min); the interface
temperature was set at 180 ꢀC.
Refraction indices were determined using IRF-22 refractometer.
Analytical TLC: Macherey-Nagel Alugram UV254; Sorbent: Silica 60,
2.2. Establishment of the structures of compounds 2aeh
2
ꢂ
specific surface (BET) w500 m /g, mean pore size 60 A, specific
pore volume 0.75 mL/g, particle size 5e17 m; Binder: highly
The structures of products 2aeh were established based on the
1H and 13C NMR spectroscopic data. The 1H NMR spectra show
signals characteristic of the open form 2aeh and the cyclic form
2a0eh0 (Scheme 4).
The percentage of the cyclic form varies from 3% in the case of 2-
hydroxy-1,5-diketone 2a to 30% in the case of 2-hydroxy-1,5-
m
polymeric product, which is stable in almost all organic solvents
and resistant towards aggressive visualization reagents. Melting
points were determined on a Kofler hot-stage apparatus. Chroma-
tography was performed on silica gel (0.060e0.200 mm, 60 A, CAS
7631-86-9).
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4
A.O. Terent’ev et al. / Tetrahedron xxx (2016) 1e6
Petroleum ether (PE) (40/70), EtOAc, CH3CN, CH2Cl2, FeS-
75.6, 208.1, 209.6. Anal. Found (%): C, 58.00; H, 8.42. C7H12O3 Calcd
(%): C, 58.32; H, 8.39. HRMS (ESI): m/z [MþNa]þ: Found: 167.0679.
Calcd for [C7H12NaO3]þ: 167.0676.
O4$7H2O, Fe(acac)2, FeBr2, Fe(ClO4)2$6H2O, FeCl2, CuBr, CuBr2,
CoBr2, Mn(OAc)3$2H2O, Mn(OAc)2$4H2O, NaHCO3, H2SO4 (98%),
and Na2SO4 were commercial reagents and were used as received.
Tricyclic monoperoxides 1aeh were synthesized according to
a procedure described previously.21
4.2.2. 3-Hydroxy-3-methylheptane-2,6-dione, 2b (1-(5-hydroxy-2,5-
dimethyltetrahydro-2-furanyl)ethanone, 2b0).
O
4.1. General procedure for the transformation of 3a-benzyl-
3,6,7a-trimethyltetrahydro-3H,4H-3,6-epoxy[1,2]-dioxolo[3,4-
b]pyran 1e (Table 1, runs 1e8). Synthesis of 3-benzyl-3-
hydroxyheptane-2,6-dione 2e
O
OH
OH
O
O
2b
2b'
Acyclic : cyclic > 0.9 : 0.1
Peroxide 1e (300 mg, 1.09 mmol) was dissolved in MeCN
(7 mL), and the solution was added with stirring at 20e25 ꢀC to
a solution of FeSO4$7H2O, Fe(ClO4)2$6H2O, FeCl2, Fe(acac)2, or
FeBr2 (1.63 mmol) in H2O (2 mL). In run 2 (Table 1), H2SO4
(200 mg, 1.99 mmol) was additionally added to a solution of
FeSO4$7H2O in H2O. The reaction mixture was stirred at
20e25 ꢀC for 1e36 h. Then CH2Cl2 (20 mL) was added. In run 2
solid NaHCO3 (340 mg, 4.00 mmol) was added to neutralize the
acid. The brown precipitate that formed was filtered off. Water
(10 mL) was added to the filtrate, and the filtrate was extracted
with CH2Cl2 (3ꢁ20 mL). The combined organic phases were
washed with water (2ꢁ10 mL), dried over Na2SO4, and filtered.
The solvent was removed using a water-jet vacuum pump.
Hydroxydiketone 2e was isolated by chromatography on silica
gel eluted with PE-EA using an elution gradient of EA from 10 to
50% (v/v). In similar experiments with CuBr, CuBr2, CoBr2,
Mn(OAc)3$2H2O, and Mn(OAc)2$4H2O, hydroxydiketone 2e was
not detected.
Yellow oil. Yield 63%, 149 mg. n2D5¼1.5240. Rf¼0.51 (TLC, PE:EA,
2:1). 1H NMR (300.13 MHz, CDCl3),
d
: 1.34 (s, 3 Hꢁ0.9), 1.41 (s,
3 Hꢁ0.1), 1.54 (s, 3 Hꢁ0.1), 1.58e1.86 (m, 2 Hꢁ0.1), 1.86e2.04 (m,
2 Hꢁ0.9þ1 Hꢁ0.1), 2.11 (s, 3 Hꢁ0.9), 2.21 (s, 3 Hꢁ0.9), 2.32 (ddd,
J¼17.9, 8.4, 6.2 Hz, 1 Hꢁ0.9), 2.39e2.47 (m, 1 Hꢁ0.1), 2.55 (ddd,
J¼17.9, 8.7, 6.1 Hz, 1 Hꢁ0.9), 3.88 (br s, 1 H). 13C NMR (75.48 MHz,
CDCl3), d: 23.7, 25.2, 29.9, 32.4, 37.5, 77.8, 208.1, 212.1. Anal. Found
(%): C, 60.52; H, 8.76. C8H14O3 Calcd (%): C, 60.74; H, 8.92. HRMS
(ESI): m/z [MþNa]þ: Found: 181.0838. Calcd for [C8H14NaO3]þ:
181.0835.
4.2.3. 3-Butyl-3-hydroxyheptane-2,6-dione, 2c (1-(2-butyl-5-
hydroxy-5-methyltetrahydro-2-furanyl)ethanone, 2c0).
O
O
OH
OH
O
O
4.2. General procedure for the synthesis of 2-hydroxy-1,5-
diketones 2aeh from tricyclic monoperoxides 1aeh (Table 2)
2c
2c'
Acyclic : cyclic > 0.9 : 0.1
Peroxide 1aeh (300 mg, 0.93e1.61 mmol) was dissolved in
MeCN (7 mL), and the solution was added with stirring at 20e25 ꢀC
to a solution of FeSO4$7H2O (389e673 mg, 1.40e2.42 mmol, 1.5 mol
FeSO4$7H2O/1 mol 1aeh) in H2O (2 mL) containing H2SO4 (0.2 g,
1.99 mmol). The reaction mixture was stirred at 20e25 ꢀC for 1 h.
Then CH2Cl2 (20 mL) and solid NaHCO3 (340 mg, 4.00 mmol) were
added to neutralize the acid. The brown precipitate that formed
was filtered off. Water (10 mL) was added to the filtrate, and the
filtrate was extracted with CH2Cl2 (3ꢁ20 mL). The combined or-
ganic phases were washed with water (2ꢁ10 mL), dried over
Na2SO4, and filtered. The solvent was removed using a water-jet
vacuum pump. Hydroxydiketones 2aeh were isolated by chroma-
tography on silica gel eluted with PE-EA using an elution gradient of
EA from 10 to 50% (v/v).
Yellow oil. Yield 84%, 208 mg. n2D5¼1.5360. Rf¼0.81 (TLC, PE:EA,
2:1). 1H NMR (major isomer) (300.13 MHz, CDCl3),
d: 0.87 (t,
J¼7.2 Hz, 3 H), 0.85e0.99 (m, 1 H), 1.21e1.35 (m, 2 H), 1.30e1.45 (m,
1 H), 1.62e1.75 (m, 2 H), 1.93e2.04 (m, 2 H), 2.11 (s, 3 H), 2.19 (s,
3 H), 2.20e2.33 (m,1 H), 2.54 (ddd, J¼17.9, 8.1, 6.7 Hz,1 H) 3.88 (br s,
1 H). 13C NMR (75.48 MHz, CDCl3),
d: 13.8, 22.9, 24.0, 25.3, 29.9, 31.9,
37.5, 38.4, 80.7, 208.0, 212.1. Anal. Found (%): C, 65.97; H, 10.20.
C
11H20O3 Calcd (%): C, 65.97; H, 10.07. HRMS (ESI): m/z [MþNa]þ:
Found: 223.1306. Calcd for [C11H20NaO3]þ: 223.1305.
4.2.4. 4-Acetyl-4-hydroxy-7-oxooctanenitrile, 2d (3-(2-acetyl-5-
hydroxy-5-methyltetrahydrofuran-2-yl)propanenitrile, 2d0).
O
O
OH
OH
O
4.2.1. 3-Hydroxyheptane-2,6-dione, 2a (1-(5-hydroxy-5-
methyltetrahydro-2-furanyl)ethanone, 2a0).
O
NC
NC
2d'
2d
O
O
Acyclic : cyclic = 0.8 : 0.2
OH
OH
O
Yellow oil. Yield 58%, 143 mg. n2D5¼1.5340. Rf¼0.35 (TLC,
O
PE:EA, 2:1). 1H NMR (400.13 MHz, CDCl3),
d
: 1.55 (s, 3 Hꢁ0.1)
2a
2a'
1.57 (s, 3 Hꢁ0.1), 1.72e2.21 (m, 4 Hꢁ0.8þ6 Hꢁ0.1þ6 Hꢁ0.1), 2.08
(s, 3 Hꢁ0.8), 2.14 (s, 3 Hꢁ0.1), 2.23 (s, 3 Hꢁ0.8), 2.24e2.53 (m,
4 Hꢁ0.8þ2 Hꢁ0.1þ2 Hꢁ0.1), 2.25 (s, 3 Hꢁ0.1). 13C NMR (major
Acyclic : cyclic > 0.97 : 0.03
Yellow oil. Yield 28%, 65 mg. n2D5¼1.5245. Rf¼0.41 (TLC, PE:EA,
2:1). 1H NMR (major isomer) (300.13 MHz, CDCl3),
d
: 1.70 (dddd,
isomer) (100.61 MHz, CDCl3), d: 11.4, 24.2, 29.8, 31.2, 33.6, 37.0,
J¼14.0, 8.3, 7.4, 5.8 Hz, 1 H), 2.16 (s, 3 H), 2.19 (dddd, J¼14.0, 7.3, 7.2,
3.7 Hz, 1 H), 2.24 (s, 3 H), 2.56 (ddd, J¼18.3, 7.3, 5.8 Hz, 1 H), 2.68
(ddd, J¼18.3, 7.4, 7.2 Hz, 1 H), 3.50 (br s, 1 H, OH), 4.17 (dd, J¼8.3,
79.3, 119.0, 207.7, 210.7. Anal. Found (%): C, 60.76; H, 7.58; N,
7.06. C10H15NO3. Calcd (%): C, 60.90; H, 7.67 N, 7.10. HRMS (ESI):
m/z [MþNa]þ: Found: 220.0952. Calcd for [C10H15NNaO3]þ:
220.0944.
3.7 Hz, 1 H). 13C NMR (75.48 MHz, CDCl3),
d: 25.1, 27.0, 29.9, 38.3,
Please cite this article in press as: Terent’ev, A. O.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.04.054

A.O. Terent’ev et al. / Tetrahedron xxx (2016) 1e6
5
4.2.5. 3-Benzyl-3-hydroxyheptane-2,6-dione, 2e (1-(5-hydroxy-5-
methyl-2-(phenylmethyl)tetrahydro-2-furanyl)ethanone, 2e0).
4.2.7. 3-Hydroxy-3-(4-nitrobenzyl)heptane-2,6-dione, 2g (1-(5-
hydroxy-5-methyl-2-((4-nitrophenyl)methyl)tetrahydro-2-furanyl)
ethanone, 2g0).
O
O
O
O
OH
OH
OH
O
OH
O
O
O
2e
2e' (mixture of isomers: A and B)
NO2
O2N
2g ' (mixture of isomers: A and B)
2g
Acyclic : cyclic (A + B) = 0.7 : 0.3
A : B = 0.2 : 0.1
Acyclic : cyclic (A + B) = 0.7 : 0.3
A : B = 0.16 : 0.14
Yellow oil. Yield 92%, 234 mg. n2D5¼1.5355. Rf¼0.60 (TLC, PE:EA,
Yellow plates (EA/PE¼1/1 (v/v)). Yield 75%, 196 mg.
Mp¼84e85 ꢀC. Rf¼0.20 (TLC, PE:EA, 2:1). 1H NMR (300.13 MHz,
2:1). 1H NMR (300.13 MHz, CDCl3),
d
ppm: 1.22 (ddd, J¼12.5, 11.0,
CDCl3),
d
ppm: 1.31e1.44 (m, 1 Hꢁ0.16), 1.52 (s, 3 Hꢁ0.16), 1.60 (s,
8.8 Hz, 1 Hꢁ0.2), 1.48 (s, 3 Hꢁ0.2), 1.54 (s, 3 Hꢁ0.1), 1.59e1.68 (m,
1 Hꢁ0.1), 1.78 (ddd, J¼12.5, 8.1, 2.2 Hz, 1 Hꢁ0.2), 1.83e1.90 (m,
1 Hꢁ0.1),1.90e1.98 (m,1 Hꢁ0.2),1.96e2.07 (m,1 Hꢁ0.7),1.99e2.09
(m, 1 Hꢁ0.1), 2.09e2.17 (m, 1 Hꢁ0.7), 2.12 (s, 3 Hꢁ0.7), 2.20 (s, 3 H),
3 Hꢁ0.14), 1.66e1.82 (m, 1 Hꢁ0.14), 1.88 (ddd, J¼12.5, 8.1, 2.2 Hz,
1
Hꢁ0.16), 1.89e2.00 (m, Hꢁ0.16), 1.80e2.15 (m,
1
2 Hꢁ0.7þ2 Hꢁ0.14), 2.12 (s, 3 Hꢁ0.7), 2.16 (s, 3 Hꢁ0.14), 2.17 (s,
3 Hꢁ0.16), 2.22 (s, 3 Hꢁ0.7), 2.18e2.28 (m, 1 Hꢁ0.14), 2.32 (ddd,
J¼18.3, 8.1, 5.9 Hz, 1 Hꢁ0.7) 2.41 (ddd, J¼13.2, 8.1, 2.9 Hz, 1 Hꢁ0.16),
2.56 (ddd, J¼18.3, 8.1, 6.6 Hz,1 Hꢁ0.7), 2.87 (d, J¼13.2 Hz,1 Hꢁ0.16),
3.05 (d, J¼13.2 Hz, 1 Hꢁ0.14), 3.07 (s, 2 Hꢁ0.7), 3.16 (d, J¼13.2 Hz,
1 Hꢁ0.16), 3.30 (d, J¼13.2 Hz, 1 Hꢁ0.14), 4.03 (br s, 1 H), 7.38 (d,
J¼8.8 Hz, 2 H), 8.10 (d, J¼8.8 Hz, 2 H). 13C NMR (major isomer)
2.29 (ddd, J¼18.0, 9.2, 5.5 Hz,
1
Hꢁ0.7), 2.29e2.44 (m,
1 Hꢁ0.1þ1 Hꢁ0.2), 2.56 (ddd, J¼17.6, 8.8, 6.0 Hz, 1 Hꢁ0.7), 2.80 (d,
J¼13.5 Hz, 1 Hꢁ0.2), 2.95 (d, J¼13.9 Hz, 1 Hꢁ0.1), 2.99 (s, 2 Hꢁ0.7),
3.02 (d, J¼13.5 Hz, 1 Hꢁ0.2), 3.10 (d, J¼13.9 Hz, 1 Hꢁ0.1), 3.80 (br s,
1 H), 7.16e7.30 (m, 5 H). 13C NMR (75.48 MHz, CDCl3),
d: 24.9, 26.4,
26.91, 29.93, 31.5, 31.9, 32.8, 37.4, 37.5, 37.8, 43.1, 44.2, 44.6, 81.3,
91.9, 106.6, 127.0, 127.9, 128.2, 129.9, 130.6, 135.2, 208.0, 211.4. Anal.
Found (%): C, 71.69; H, 7.71. C14H18O3 Calcd (%): C, 71.77; H, 7.74.
HRMS (ESI): m/z [MþNa]þ: Found: 257.1149. Calcd for
[C14H18NaO3]þ: 257.1148.
(75.48 MHz, CDCl3),
d: 24.7, 29.9, 31.5, 37.4, 44.2, 81.0, 123.1, 130.9,
143.1, 147.1, 208.0, 210.8. Anal. Found (%): C, 60.17; H, 6.18, N, 5.06.
C
14H17NO5 Calcd (%): C, 60.21; H, 6.14, N, 5.02. HRMS (ESI): m/z
[MþNH4]þ: Found: 297.1444. Calcd for [C14H21N2O5]þ: 297.1445.
4.2.8. 2-Hydroxy-1-phenylhexane-1,5-dione, 2h ((5-hydroxy-5-
methyltetrahydro-2-furanyl)(phenyl)methanone, 2h0).
4.2.6. 3-Hydroxy-3-(4-methylbenzyl)heptane-2,6-dione, 2f (1-(5-
hydroxy-5-methyl-2-((4-methylphenyl)methyl)tetrahydro-2-furanyl)
ethanone, 2f0).
O
O
OH
OH
O
O
O
O
OH
OH
O
2h
2h'
O
Acyclic : cyclic > 0.95 : 0.05
Yellow oil. Yield 83%, 207 mg. n2D5¼1.5250. Rf¼0.37 (TLC, PE:EA,
2:1). 1H NMR (major isomer) (300.13 MHz, CDCl3),
d: 1.55 (dddd,
2f
2f ' (mixture of isomers: A and B)
J¼14.2, 9.3, 6.3, 5.3 Hz, 1 H), 2.16 (s, 3 H), 2.28 (dddd, J¼14.2, 8.5, 6.4,
2.9 Hz, 1 H), 2.55 (ddd, J¼18.5, 6.4, 5.3 Hz, 1 H), 2.86 (ddd, J¼18.5,
8.5, 6.3 Hz, 1 H), 3.68 (br.s 1 H), 5.09 (dd, J¼9.3, 2.9 Hz, 1 H),
7.47e7.54 (m, 2 H), 7.58e7.65 (m, 1 H), 8.03e8.09 (m, 2 H). 13C NMR
Acyclic : cyclic (A + B) = 0.82 : 0.18
A : B = 0.12 : 0.06
(75.48 MHz, CDCl3), d: 29.7, 29.9, 38.4, 71.7, 128.7, 128.8,133.1, 134.0,
Yellow oil. Yield 83%, 213 mg. n2D5¼1.5280. Rf¼0.69 (TLC, PE:EA,
201.6, 208.3. Anal. Found (%): C, 69.72; H, 6.85. C12H14O3 Calcd (%):
C, 69.89; H, 6.84. HRMS (ESI): m/z [MþNa]þ: Found: 229.0826.
Calcd for [C12H14NaO3]þ: 229.0835.
2:1). 1H NMR (300.13 MHz, CDCl3),
d
ppm: 1.27 (m, 1 Hꢁ0.12), 1.49
(s, 3 Hꢁ0.12), 1.54 (s, 3 Hꢁ0.06), 1.65 (m, 1 Hꢁ0.06), 1.79 (ddd,
J¼12.5, 8.1, 2.9 Hz, 1 Hꢁ0.12), 1.84e1.94 (m, 1 Hꢁ0.06), 1.96e2.04
(m, 1 Hꢁ0.12), 2.04e2.07 (m, 1 Hꢁ0.82), 2.04e2.14 (m, 1 Hꢁ0.06),
2.13 (s, 3 Hꢁ0.82), 2.14e2.34 (m, 2 Hꢁ0.82), 2.20 (s, 3 H), 2.30 (s,
3 Hꢁ0.82), 2.29e2.39 (m, 1 Hꢁ0.06), 2.36e2.43 (m, 1 Hꢁ0.12), 2.56
(ddd, J¼17.6, 8.8, 5.9 Hz, 1 Hꢁ0.82), 2.76 (d, J¼13.2 Hz, 1Hꢁ0.12),
2.90 (d, J¼13.2 Hz, 1 Hꢁ0.06), 2.96 (s, 2 Hꢁ0.82), 2.99 (d, J¼13.2 Hz,
1 Hꢁ0.12), 3.06 (d, J¼13.2 Hz, 1 Hꢁ0.06), 3.76 (br s, 1 H), 7.07 (m,
Acknowledgements
This study was financially supported by the Russian Science
Foundation (Grant 14-23-00150).
Supplementary data
4 H). 13C NMR (major isomer) (75.48 MHz, CDCl3),
d: 21.1, 25.0, 30.1,
31.6, 37.7, 44.4, 81.5, 129.1, 129.8, 132.2, 136.6, 208.1, 211.6. Anal.
Found (%): C, 72.40; H, 8.15. C15H20O3 Calcd (%): C, 72.55; H, 8.12.
HRMS (ESI): m/z [MþNa]þ: Found: 271.1305. Calcd for
[C15H20NaO3]þ: 271.1305.
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2016.04.054.
These data include MOL files and InChiKeys of the most important
compounds described in this article.
Please cite this article in press as: Terent’ev, A. O.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.04.054

6
A.O. Terent’ev et al. / Tetrahedron xxx (2016) 1e6
20. (a) Hawkins, E. G. E.; Young, D. P. J. Chem. Soc. 1950, 2804e2808; (b) Hawkins,
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