Transformations of 6,7-epoxy derivatives of citral and citronellal in various acidic media

Article abstract of DOI:10.1023/A:1022501815715

The transformations of 6,7-epoxy derivatives of widely spread in the nature unsaturated aldehydes, citral and citronellal, in various acidic media both under conditions of homogeneous and heterogeneous catalysis were investigated. A number of previously unknown products belonging to different classes of organic compounds was obtained. Probable mechanisms of the products formation are discussed.

Full text of DOI:10.1023/A:1022501815715

Russian Journal of Organic Chemistry, Vol. 38, No. 11, 2002, pp. 1594 1605. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 11, 2002,
pp. 1649 1660.
Original Russian Text Copyright
2002 by Yarovaya, Salomatina, Korchagina, Polovinka, Barkhash.
Transformations of 6,7-Epoxy Derivatives of Citral
and Citronellal in Various Acidic Media
O. I. Yarovaya1, O. V. Salomatina2, D. V. Korchagina1,
M. P. Polovinka1, and V. A. Barkhash1
1Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division,
Russian Academy of Sciences, Novosibirsk, 630090 Russia
2Novosibirsk State University, Novosibirsk, 630090 Russia
Received February 20, 2002
Abstract The transformations of 6,7-epoxy derivatives of widely spread in the nature unsaturated
aldehydes, citral and citronellal, in various acidic media both under conditions of homogeneous and
heterogeneous catalysis were investigated. A number of previously unknown products belonging to different
classes of organic compounds was obtained. Probable mechanisms of the products formation are discussed.
The extensive study of terpenes and their deriva-
tives in the modern chemistry is due both to their
polyfunctionality and therefore versatile reactivity and
to application of this class compounds to many fields
of human activity, for instance, to medicine and
perfumery [1]. Investigations on epoxides of the
terpene series that are able to transform into alcohols,
aldehydes, ketones, and heterocycles is a very
promising field in the terpene chemistry. Besides the
introduction of an epoxy group into a molecule of
a complex polyfunctional natural compound can mark
the place where arises a cationic center thus provid-
ing a possibility of making assumptions on the
mechanism of carbocationic reactions and of compari-
son with the acid-catalyzed reactions of the original
olefins.
Scheme 1.
We showed before [4] that treating of citral with
peracetic acid provided 6,7-derivatives of geranial
(cis-citral) (III) and neral (trans-citral) (IV). Along-
side these epoxides formed (E)- (V) and (Z)- (VI)
2,6-dimethyl-5,6-epoxy-1-heptenyl formates arising
from epoxidation and Bayer Williger reaction
(Scheme 2).*
The objects of this study were citral and citronellal
epoxidized at the 6,7-double bond. The transforma-
tions of the original unsaturated aldehydes in the
acidic media were formerly investigated. It is known
from the published data [2] that under treatment
with acids citral (I) and citronellal (II) undergo
cyclization to afford p-cymene and isopulegol re-
spectively. Besides it was shown earlier [3] that at
dissolution of isomeric aldehydes I in a system
HSO3F SO2FCl at 120 C under long life condi-
tions a mixture of two carboxonium ions (A) and (B)
was formed, and the dissolution of isomers I in a
system SbF5 HSO3F SO2FCl at 95 C resulted in
dications (C) and (D). The dissolution of citronellal
(II) in the fluorosulfonic acid (HSO3F SO2FCl at
120 C) furnished an allyl ion (E). The NMR spectra
of the observed ions did not change from 100 to
60 C (Scheme 1).
Scheme 2.
We studied reactions of epoxides III and IV in
various acidic media. The equimolar mixture of iso-
mers III and IV was dissolved in fluorosulfonic acid
1070-4280/02/3811-1594$27.00 2002 MAIK Nauka/Interperiodica

TRANSFORMATIONS OF 6,7-EPOXY DERIVATIVES
1595
Table 1. Ratio of reaction products VII XV depending on reaction conditions
Reaction
conditions
VII
VIII
IX
X
XI
XII
XIII XIV XV
III
HSO3F SO2FCl, 115 C
25
75
Dioxane H2O H2SO4 40: 6: 1, 1 min
Dioxane H O H2SO 40: 6: 1, 1 h
CH3COCH32 H2O H42SO4 40: 6: 1, 1min
CH3COCH3 H2O H2SO4 40: 6: 1, 1 h
Askanite bentonite clay, 5 min
Zeolite , 5 min
70
30
43
13
30
70
36
26
7
21
14
40
45
30
5
20
50
50
TiO2/SO24 , 10 min
18
30
7
17
30
a
Percent according to GLC data at 1: 1 ratio of the original epoxides III and IV.
at molar ratio HSO3F to aldehyde mixture III+ IV
20: 1, SO2FCl HSO3F at a ratio 4: 1 by volume, and
reaction temperature 115 C. On quenching the acid
solution with a mixture methanol ethyl ether, 5: 2,
a mixture was obtained of (E)- (VII) and (Z)- (VIII)
3,7-dimethyl-6-oxo-2-octenals (Scheme 3). The dis-
solution of epoxides III and IV in a system dioxane
water H2SO4 at volume ratio 40: 6: 1 with subsequent
neutralization of the acid by sodium carbonate
resulted in formation of (2R,5R)- (IX) and (2S,5R)-
(X) 5-(1-hydroxy-1-methylethyl)-2-methyltetrahydro-
furan-2-acetaldehydes. The ratio of the arising pro-
ducts essentially depended on the reaction time and is
independent of the initial reagent ratio. If the reaction
is stopped in 1 min the main product is compound IX,
and neutralization of the reaction mixture in 1 h and
more affords predominantly compound X (Table 1).
The mechanism of compounds IX and X formation
we assumed is shown on Scheme 3. It is suggested
that a molecule of water adds to primarily arising
cations (F) and (G) with subsequent protonation of the
2,3-double bond resulting in ion (H). The latter
undergoes cyclization to furnish the substituted tetra-
hydrofurans IX and X. This mechanism assuming
formation of the same ion (H) from two different com-
pounds explains why the initial ratio of epoxides III
and IV does not influence the reaction products ratio.
With no acid compound IX does not isomerize, and
at dissolution of the isolated substance IX in the
system dioxane water H2SO4 compound X also does
not form. Semiempirical calculations of the thermo-
dynamic stability for isomers IX and X show that
compound X is more thermodynamically stable [ Hf0
X
were obtained (E)- (XI) and (Z)- (XII)
3,7-dimethyl-6,7-isopropylidenedioxy-2-octenals.
Cations (H) and (G) arising on the opening of the
epoxy ring either react with the external nucleophile
(acetone) affording ketals XI and XII or cyclize to
give the tetrahydrofuran derivatives IX and X. It
should be noted that the ratio of ketals XI and XII
does not depend either on the reaction time or the
ratio of the initial epoxides evidencing the existence
of the acid-catalyzed equilibrium between (H) and (G)
ions. At the same time the relative amount of com-
pounds IX, X versus (XI+ XII) depends on the
duration of the process in the acidic medium.
We studied further the isomerization of epoxides
III and IV under conditions of heterogeneous
catalysis. It was demonstrated, that application of
equimolar mixture of compounds III and IV dissolv-
ed in CH2Cl2 on zeolite or askanite bentonite clay
for 5 min at room temperature did not cause iso-
merization of epoxide III with trans-located substitu-
ents at the double bond, whereas epoxide IV apparent-
ly due to its spatial arrangement suffered a trans-
formation into cyclic products, 4,8,8-trimethyl-7,9-
dioxabicyclo[4.2.1]non-4-ene (XIII) and 2,2,6-tri-
methyl-3,9-dioxabicyclo[4.2.1]non-4-ene (XIV). De-
pending on the type of the acid catalyst used com-
pounds XIII and XIV were obtained in different
amounts.
As seen from the mechanism we proposed in
Scheme 3 for the formation of bicyclic ethers the
stabilization of cationic center on ion (G) arising at
the rupture of the epoxy ring occurs through its reac-
tion with the carbonyl oxygen resulting in a cyclic
ion (I). Further the OH group of ion (I) either reacts
with the carbon atom C2 to yield compound XIII
or with the atom C4 providing compound XIV. The
comparison with published data shows that ion (I) is
structurally similar to cyclic ions (A) and (B) arising
1
1
(IX) 151.10kcal mol , H0f (X) 152.26kcal mol ;
MOPAC].
At dissolving epoxides III and IV in a system
acetone water H2SO4 at molar ratio 40: 6: 1 along-
side the isomeric substituted tetrahydrofurans IX and
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

1596
YAROVAYA et al.
Scheme 3.
from the initial compound I in the system HSO3F
SO2FCl at 120 C [3]. The stabilization of a carbo-
cationic center by reaction with a carbonyl oxygen
yielding carboxonium ions as with compound I is
fairly common for cyclization reactions of acyclic
terpenoids containing a carbonyl group [5].
important factor influencing the formation of dica-
tions or cyclic ions from aldehydes I was the ratio of
acid to the initial compound. Yet it is known that the
acidity of the solid superacid is significantly stronger
than that of the clay and the zeolite we used. This fact
may testify to the mechanism of compounds XV
formation via a dication, but the possibility of the
other mechanisms cannot be excluded.
At the use of another solid catalyst, solid superacid
TiO2/SO24 , the isomerization of epoxides III and IV
gives rise to ketoaldehydes VII and VIII, tetrahydro-
furan derivatives IX and X, and also to a mixture
(4: 1) of diastereomers 5-isopropenyl-2-methyltetra-
hydrofuran-2-acetaldehydes (XV). The ratio of the
forming products is weakly sensitive to the type of
the solid superacid used and to the duration of the
reaction. Note that keeping compounds IX and X
with the heterogeneous catalyst does not afford com-
pounds XV. We believe that on the route to isomers
XV arises dication (J) of structure similar to that of
ions (C) and (D). This dication cyclizes to give the
tetrahydrofuran skeleton. It was remarked [3] that an
We showed further that at dissolving the epoxides
V and VI mixture at 2: 1 ratio in a system HSO3
SO2FCl at 115 C arose a mixture of (E)- (XVI),
(Z)- (XVII) 2,6-dimethyl-oxo-1-heptenyl formates,
and 2,6-dimethyl-5-oxoheptanal (XVIII) in 2: 1: 4
ratio respectively (Scheme 4). The shortening of the
chain by one atom as in compound XVIII was
previously observed by Prilezhaev [6] in oxidation of
the original aldehyde I with perbenzoic acid. The
isomerization of epoxyformates V and VI on solid
catalysts provided intractable mixtures of compounds.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

TRANSFORMATIONS OF 6,7-EPOXY DERIVATIVES
1597
Schemes 4.
Next we studied the acid-catalyzed reactions of
epoxides of citronellal (II), an acyclic monoterpene
structurally similar to compound I. It was shown that
at oxidation of citronellal II with peracids formed
both 6,7-epoxy derivatives (XIX) as a mixture of
diastereomers and the isomer of the original com-
pound isopulegol (XX) (Scheme 5).
by the paths a and b. According to path a the epoxide
ring first opens to form ion (L), and then it suffers
further transformation into compound XXI. Along
path b in the first stage occurs a protonation of
carbonyl group giving ion (M), then the reaction of
the epoxy oxygen with the cationic center gives rise
to trialkyloxonium ion (N). The rupture of C7 O
bond in the latter furnishes a cyclic cation (O), and
its quenching with a mixture methanol ether yields
compound XXII. The mechanism of ion (N) forma-
tion we assumed basing on the published data.
Formerly a stable trialkyloxonium ion (P) was
generated from -bisabolol (XXIII) in a system
SO2FCl HSO3F at 80 C [7], and trialkyloxonium
ion (Q) was assumed as an intermediate in isomeriza-
tion of 2,3-epoxygeraniol (XXIV) in the system
SO2FCl HSO3F at 100 C [8] (Scheme 7).
Scheme 5.
Compounds XIX were dissolved in fluorosulfonic
acid at molar ratio HSO3F to compound XIX 15: 1,
SO2FCl HSO3F at a ratio 4: 1 by volume, and reac-
tion temperature 105 C. On quenching the acid
solution with a mixture methanol ethyl ether, 5: 2,
were obtained 2.6-dimethyl-8,8-dimethoxyoctan-3-one
(XXI) and 4-methyl-2-methoxy-7-(1-methoxy-1-
methylethyl)1-oxacycloheptane (XXII) (Scheme 6).
Dissolving epoxides XIX in a system acetone
water H2SO4 at molar ratio 40: 6: 1 gave rise to
3,7-dimethyl-6-oxooctanal (XXV) and 3,7-dimethyl-
6,7-isopropylidenedioxyoctanal (XXVI) as a mixture
of diastereomers (Scheme 8). The isomerization of
epoxides XIX on heterogeneous acid catalysts, such
as zeolite , askanite bentonite clay, and solid super-
acid TiO2/SO24, afforded alongside the ketoaldehyde
XXV also 4,8,8-trimethyl-7,9-dioxabicyclo[4.2.1]-
The presumable mechanism of this reaction is
shown in Scheme 6. It follows from the Scheme that in nonane (XXVII) as a mixture of isomers. The reac-
a superacid epoxides XIX can undergo transformation tion products XXV and XXVII formed in different
Scheme 6.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

1598
YAROVAYA et al.
endo- (XXX) brevicomin (XXX), - and -multi-
Scheme 7.
stearin (XXXI) are active components of pheromone
compositions controlling the aggregation of bark
beetles from the genera Dendroctonus and Dryocoetes
and of bark beetles from the genus Scolytus [9].
Besides the three-component pheromone of male
hepialid moth Hepialus hecta is known to contain two
unsaturated compounds of the 2,9-oxabicyclo[3.2.1]-
non-7-ene series, XXXII and XXXIII, and unsaturat-
ed analog of the exo-brevicomin XXXIV is a multi-
functional pheromone of house mice Mus musculus.
Let us discuss some details of structure determina-
tion for the compounds obtained. The 1H NMR
spectrum of compound III is identic to that published
[10].
ratios depending on the type of catalyst used (Table2).
The formation of cyclic compound XXVII evidences
that in the intermediate stage arises a cyclic ion (R)
with a structure similar to that of ion (I) from
epoxide IV.
The assignment of respective trans- and cis-struc-
tures to compounds IX and X was done by analogy
with the chemical shifts of carbons in the published
13C NMR spectra of compounds with related trans-
and cis-structures XXXV and XXXVI [11]. The
alternative pyran type structures XXXVIIa, b were
It is remarkable that bicyclic ketals obtained by us
XIII, XIV, XXVII are structural analogs of well-
known pheromones XXVIII XXXIV. Intramolecular
bicyclic ketals frontalin (XXVIII), exo- (XXIX) and
Scheme 8.
Scheme 9.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

TRANSFORMATIONS OF 6,7-EPOXY DERIVATIVES
1599
rejected after comparison of the NMR spectra with
the corresponding spectra from the literature [12]
belonging to compounds of analogous structure
XXXVIIIa, b. The choice between the alternative
structures XXII and XXXIX was done basing on the
LRJMD spectrum that permitted rejection of structure
XXXIX. Decoupling from protons of methoxy groups
performed separately for signals at 3.18 and 3.26ppm
resulted in appearance in the first case only of a
singlet from carbon atom at 76.61 ppm (C10 in struc-
ture XXI), and in the second case was observed a
doublet signal at 102.67 ppm assigned to carbon atom
C2. The decoupling from methoxy group signal at
3.18 ppm should have resulted for compound XXXIX
by appearance in the LRJMD spectrum of a doublet
belonging to carbon atom C7 at 75.56 ppm, and that
was not actually observed.
Table 2. Ratio of reaction products XXI, XXII,
XXV XXVII (% according to GLC ) depending on
isomerization conditions of epoxyaldehyde XIX
Reaction
XXI XXII XXV XXVI XXVII XIX
conditions
HSO3F SO2FCl, 80
115 C
20
CH3COCH3
H2O H2SO4
40: 6: 1, 10 min
Askanite
bentonite clay,
5 min
10
40
90
30
30
25
zeolite
,
30
60
45
40
15 min
TiO2/SO24 , 10min
EXPERIMENTAL
1H and 13C NMR spectra were registered on
spectrometer Bruker AM-400 at 400.13 and
100.61 MHz respectively from solutions of com-
pounds in CDCl3 or in a mixture CCl4 CDCl3
( 1: 1). The chloroform signals served as internal
reference ( 7.24,
76.90 ppm). The structures of
compounds obtainedCwere established by analysis of
the coupling constants in the NMR spectra of double
1
resonance 1H H, and by analysis of 13C NMR
spectra with the use of spectra with selective and
off-resonance protons irradiation, two-dimensional
1
correlation spectra 13C H on direct constants
1
(COSY, the applied value of JC,H 135 Hz), and
1
unidimensional spectra 13C H with correlation on
remote constants (LRJMD, JC,H 10 Hz). Data on
13C NMR spectra are presented in Table 3.
Thus in this study the acid-catalyzed reactions of
6,7-epoxides prepared from the aldehydes widely
spread in the nature, citral (I) and citronellal (II),
were investigated under various homogeneous and
heterogeneous conditions. Owing to the polyfunc-
tional character of terpenoid molecules they possess
versatile reactivity that depends on the reaction
conditions. Therewith in these strongly bonded multi-
center systems relatively small structural changes
result in significant variations. In keeping with the
type of the acid catalyst the reaction products can
belong to various classes of organic compounds; it is
besides demonstrated that varying the nature of the
acid catalyst and the duration of the reaction it is
possible to change the ratio of the forming substances.
The analysis of reaction products and checking of
the initial compounds purity was performed by GLC
on Biokhrom-1 chromatograph equipped with
several columns: (a) glass capillary column 53000
0.26 mm, stationary phase XE-60; (b) quartz capil-
lary column 13000 0.22 mm, stationary phase
SE-54; (c) quartz capillary column 20000 0.27 mm,
stationary phase BS-30 (analogous to SE-30); flame-
ionization detector, carrier gas helium. The ratios of
product formed from epoxides III, IV under acid
catalysis are given in Table 1, those arising from
epoxides XIX in Table 2. The separation of reaction
products was carried out by column chromatography
on SiO2 (Czech Republic, 40 100 and 100 160 ).
The ratio of crude product to the sorbent was 1: 20
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

1600
YAROVAYA et al.
1
1: 40. The elemental composition of compounds
obtained was derived from the high resolution mass
spectra registered on Finnigan MAT 8200 instrument.
168.11502. H NMR spectrum of 6,7-epoxygeranial
(III) ( , ppm, J, Hz): 1.18 s and 1.21
s
(C8H3, C10H3), 1.54 1.74 m (2H5), 2.11 d (C9H3,
J9,2 1.2), 2.20 2.37 m (2H4), 2.63 d.d (H6, J6,5
7, J6,5 5), 5.81 d.m (H2, J2,1 8), 9.89 d (H1, J 8).
1H NMR spectrum of 6,7-epoxyneral (IV) ( , ppm,
J, Hz): 1.23 s and 1.26 s (C8H3, C10H3), 1.66
1. 78 m (2H5), 1. 96 d (C9H3 J9,2 1.2), 2.63
2.76 m (2H4, H6), 5.88 br.d (H2, J2,1 8), 9.93 d
(H1, J 8).
The solutions of ion salts were prepared in twice
distilled HSO3F (bp 158 161 C). The diluent,
SO2FCl, was purified by passing through sulfuric
acid. As nucleophile for quenching was used a mix-
ture methanol ethyl ether, 5: 2 by volume. The
procedures for preparation of salts solutions and their
quenching are described in [13]. The askanite ben-
tonite clay used as catalyst was prepared by acid
activation of clay from Askane group of deposits,
State Standard OCT 113 12-86-82, and it was dried
directly before experiments at 110 C for 3 h. As
catalysts were also used titanium oxide sulfate
(TiO2/SO24 ) (calcined at 400 C for 3 h) or wide-
Mass spectrum of compounds V, VI mixture
(2: 1): m/z 156.11493 (fragment ion [M CO]+ )
C9H16O2. Calculated. ([M CO]+ ) 156.11502.
1H NMR spectrum of (E)-2,6-dimethyl-5,6-epoxy-
1-heptenyl formate (V) ( , ppm, J, Hz): 1.17 s
and 1.21 s (C7H3, C10H3), 1.57 m (2H4), 1.63 d
(C9H3, J9,1 1.5), 1.98 2.15 m (2H3), 2.60 t (H5,
J5,4 6), 6.93 m (H1, J1,3 1.5, J 1.5), 7.96 s (H8).
1H NMR spectrum of (Z)-2,6-dimethyl-5,6-epoxy-1-
heptenyl formate (VI) ( , ppm, J, Hz): 1.22 s and
1.25 s (C7H3, C10H3), 1.60 m (2H4), 1.64 d (C9H3,
J9,1 1.5), 2.26 br.t (2H3, J3,4 7.5, J3,1 1), 2.67 t
(H5, J5,4 6), 6.94 m (H1, J 1.5, 1), 8.00 s (H8).
porous zeolite
(SiO2/Al2O3 22.4) with pore size
0.75 0.80 nm, weight content of oxides Na2O 0.01%,
Al2O3 4.50%, SiO2 59.20%, Fe2O3 0.08% (manufac-
tured at TsIN Zeosit, Novosibirsk). Zeolite was
calcined before use for 3 h at 500 C. The following
reagents were used in the study: citral Fluka contain-
ing no less than 97% of the main product, ratio of cis
to trans isomers 1: 2 (1H NMR data); technical-grade
citral containing 13% of dehydrolinalool, ratio of cis
to trans isomers 1: 1 (1H NMR data); citronellal
Fluka with content of the main substance 85 90%.
Transformation of epoxides III, IV in HSO3F
SO2FCl at 115 C. To a solution of 2.8 g (1.6 ml)
of HSO3F in 6.4 ml of SO2FCl was added at 115 C
a solution of 0.3 g of epoxides III, IV mixture (with
the ratio of E and Z isomers 2: 1) in 1.8 ml of
CH2Cl2. The reaction mixture was vigorously stirred
for 5 min at the same temperature, and then poured
into a mixture of methanol with ethyl ether. Yield of
the crude reaction product 0.9 g. By column
chromatography on SiO2 (eluent hexane) was separat-
ed 0.05 g of a mixture of compounds VII and VIII in
3: 1 ratio. Found [M]+ 168.11495. C10H16O2. Cal-
culated M 168.11502. 1H NMR spectra (recorded
from the mixture of compounds VII and VIII in the
ratio 3: 1), , ppm (J, Hz): (E)-3,7-dimethyl-6-oxo-
2-octenal (VII), 1.082 d (C8H3, C10H3, J 7), 2.17 d
(C9H3, J9,2 1.2), 2.43 br.t (2H4, J4,5 7.5), 2.57 septet
(H7, J 7), 2.63 t (2H5, J 7.5), 5.77 d.q.t (H2, J2,1 7.5,
J 1.2, J2,4 1.2), 9.93 d (H1, J 7.5); (Z)-3,7-dimethyl-
6-oxo-2-octenal (VIII), 1.079 d (C8H3, C10H3, J 7),
1.93 d (C9H3, J9,2 1.2), 2.55 septet (H7, J 7), 2.63 m
(2H5), 2.79 br.t (2H4, J4,5 7), 2.82 br.d (H2, J2,1 7.5),
9.91 d (H1, J 7.5).
Reaction of citral (I) with peracetic acid. To 2.12
g (0.014 mol) of compound I (with cis-to-trans ratio
1: 2) in 3 ml of CH2Cl2 and 8 g of anhydrous Na2CO3
was added slowly at vigorous stirring 24 ml
(0.021 mol) of CH3COOOH dissolved in CH2Cl2.
The peracetic acid was preliminary prepared by
extraction from the mixture of 200 ml CH3COOH,
200 ml of 30% H2O2, and 10 ml of H2SO4, and its
concentration was determined by iodometry. After the
end of peracetic acid addition the reaction mixture
was vigorously stirred for 50 min at 20 C. The
epoxides were extracted from the reaction mixture by
ethyl ether, the extract was treated with saturated
solution of Na2CO3, washed with water till neutral,
and dried on Na2SO4. The weight of crude product
2.08 g. In the mixture epoxides III, IV, V, and VI
were present in 28, 21, 30, 21% amount respectively
according to GLC. The products were separated by
column chromatography on SiO2 (100 160 ),
gradient elution with hexane ethyl ether mixture,
ether content from 5 to 30%. We obtained 0.75 g of
compounds III and IV mixture in 2: 1 ratio, and
1.28 g of compounds V and VI mixture in 2: 1 ratio.
Mass spectra of isomers III and IV are identic.
Found [M]+ 168.11495. C10H16O2. Calculated M
Isomerization of the epoxides III and IV mixture
in a system dioxane water H2SO4. To 1.5 ml of a
mixture dioxane water H2SO4 (40: 6: 1 by volume)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

TRANSFORMATIONS OF 6,7-EPOXY DERIVATIVES
1601
Table 3. 13C NMR spectra of compounds III XIX, XXI, XXII, XXV XXVII, C, ppma
Number of
IIIb
IVb
Vb
VIb
VIIc
VIIIc
IXc
Xc
XIc
carbon atom
1
2
190.94 d 190.31 d 128.96 d 128.91 d 190.04 d 189.72 d
79.91 s
127.15 d 128.55 d 122.38 s
162.54 s 162.73 s 30.54 t
122.55 s 126.98 d 128.64 d 80.99 s
81.05 s
38.15 t
25.89 t
3
26.35 t
26.44 t
161.44 s 161.22 s 37.93 t
106.79 s
4
37.01 t 29.30 t
26.35 t 27.88 t
63.08 t 63.10 t
26.77 t
63.35 d
57.97 s
33.66 t
26.52 t
38.67 t
26.03 t
86.09 d
5
63.64 d 37.31 t
85.63 d 82.46 d
54.09 t 26.99 t
18.52 q 40.89 d 40.86 d 200.59 d 200.90 d 37.78 t
6
58.15 s 211.44 s 211.44 s 54.00 t
7
58.29 s 58.47 s 18.44 q
8
18.42 q 18.55 q 157.66 d 157.72 d 18.26 q 18.19 qe 27.56 q
26.89 q 162.08 s
70.58 s 127.30 d
24.63 qe 190.36 d
27.48 qe 22.92 qe
25.97 qe
9
17.34 q 24.77 q 13.48 q
24.45 q 24.54 q 24.49 q
17.26 q 17.91 q 24.79 q 70.31 s
24.65 q 18.26 q 18.26 qe 24.31 qe
27.39 qe
10
11
12
13
14
15
26.89 qf
28.51 qf
17.63 q
Number of
XIIc
XIIIc
XIVc
XVc
XVIb
XVIIb
XVIIIb
XIXac
XIXbc
carbon atom
1
2
79.76 s 100.11 d 83.02 d
125.95 d 81.80 s
129.09 d 128.91 d 204.32 d 200.66 s 200.59 s
81.07 s 122.49 s 122.49 s 45.47 d 50.63 t 50.80 t
27.69 d 27.69 d
3
106.88 s 142.66 s
37.83 t
141.12 d 31.00 t
27.74 t
38.15 t
23.75 t
37.66 t
24.05 t
36.97 t
4
30.34 t
33.54 t
26.23 t
33.54 t
26.23 t
5
81.74 d 28.71 t
114.13 d 82.45 d 213.33 s 213.61 s 213.67 s
54.25 t 40.81 d 40.69 d 40.76 d
6
27.84 t
29.76 t
161.73 s
80.67 d 80.67 s
63.53 d 63.55 d
57.60 s 57.50 s
18.66 q 18.62 q
19.87 q 19.74 q
24.74 q 24.74 q
7
80.35 s 41.04 t
25.08 t
200.36 d 18.06 q 18.08 q 18.06 q
27.81 q 157.81 d 157.74 d 13.34 q
145.12 s 13.77 q 17.32 q 18.06 q
110.53 t 18.06 q 18.08 q
18.07 q
8
9
129.18 d 26.10 q 25.65 qe
190.36 d 27.96 qe 23.42 qe
22.97 qe 21.10 qe 26.23 q
25.89 qe
10
11
12
13
14
15
26.76 qf
28.51 qf
24.68 q
Number of
XXIc
XXIIc
XXVb
XXVIa, bc
XXVIIbb
XXVIIbb
carbon atom
1
2
18.20 qe
40.69 d
214.37 s
37.66 t
30.64 t
28.67 d
39.20 t
102.86 d
18.17 qe
19.56 q
52.52 qf
52.22 qf
200.63 s
50.90 t
27.62 d
30.47 t
37.57 t
212.59 s
40.76 d
18.34 qe
19.86 q
18.32 qe
79.86 s
102.32 d
43.27 t
30.49 d
32.16 t
30.81 t
81.70 d
79.72 s
104.03 d
43.13 t
28.57 d
31.92 t
26.52 t
80.21 d
81.32 s
102.67 d
38.15 t
28.97 d
42.87 t
29.22 t
75.56 d
55.80 q
24.31 q
76.61 s
22.54 qe
20.77 qe
49.11 q
3
106.44 s
4
5
83.26 d, 83.42 d
26.87 t
6
7
34.23 t, 34.31 t
28.11 d, 28.19 d
50.89 t, 50.91 t
200.63 d, 200.67 d
22.92 qe
8
9
23.34 q
26.29 qe
20.98 qe
22.88 q
27.52 qe
22.19 qe
10
11
12
13
14
15
26.14 qe
26.93 qf
28.63 qf
19.99 q
a
The chemical shift values with the same superscripts (e, f) probably would be interchanged within the same column.
b
c
In CDCl3.
In CCl4+CDCl3 (1: 1).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

1602
YAROVAYA et al.
was added 0.1 g of epoxides III and IV mixture (1: 1). (XI) ( , ppm, J, Hz): 1.05 s, 1.20 s (C11H3, C12H3),
1.26 s, 1.35 s (C13H3, C14H3), 1.50 d.d.d.d (H6,
In 1 min the reaction mixture was washed with a
saturated Na2CO3 solution, the reaction products were
extracted into ethyl ether. The crude product weight-
(H6 , J 13.5, J6 ,5 10, J6 ,7 10, J6 ,7 5), 2.16 d
ed 0.07 g, the ratio of compound IX to X 2.3 : 1
J6,6 13.5, J6,7 10.5, J6,7 6, J6,5 3), 1.65 d.d.d.d
(C15H3, J15,9 1.5), 2.23 d.d.d.d (H7, J7,7 15, J 10,
(GLC) was not influenced by the ratio of the original
6, J7,9 1), 2.44 d.d.d.d (H7 , J 15, 10.5, 5, J7 ,9 1),
3.58 d.d (H5, J 10, 3), 5.85 d.m (H9, J9,10 8), 9.95 d
epoxides III and IV. Found [M]+ 186.11495.
C10H16O2. Calculated M 186.11502. The products
were subjected to column chromatography on SiO2,
gradient elution with hexane ethyl ether mixture,
ether content from 0.5 to 25%. We obtained 0.021 g
of compounds IX and X mixture in 3: 1 ratio. At
keeping 0.15 g of the epoxides mixture in 2.3 ml of
the system dioxane water H2SO4 for 1 h 0.12 g of
crude product was isolated with compound IX to X
ratio 1: 2.3. By chromatography on SiO2, gradient
elution with hexane ethyl ether mixture, ether content
from 0.5 to 25%, 0.04 g of compounds IX and X
mixture, 1: 3, was isolated.
1
(H10, J 8). H NMR spectrum of (Z)-3,7-dimethyl-
6,7-isopropylidenedioxy-2-octenal (XII2) ( , ppm, J,
Hz): 1.04 s, 1.18 s (C11H3, C12H3), 1.23 s, 1.35 s
(C13H3, C14H3), 1.51 m (H6), 1.68 m (H6 ), 1.96 d
(C15H3, J15,9 1.5), 2.58 d.d.d.d (H7, J7,7 13, J7,6 8,
J7,6 5, J7,9 0.5), 2.83 d.d.d (H7 , J 13, J7 ,6 8, J7,6 8),
3.57 d.d (H5, J5,6 10.5, J5,6 3), 5.86 d.m (H9, J9,10
8), 9.92 d (H10, J 8).
Isomerization of the epoxides III and IV mix-
ture on zeolite. To 0.40 g of calcined zeolite in 6 ml
of dried CH2Cl2 was added at stirring 0.25 g of
epoxides III amd IV mixture (1: 1) in 1 ml of
CH1Cl2. After 5 min of stirring the catalyst was
filtered off and washed with ethyl ether. The solvent
was removed from the combined organic solution to
afford 0.22 g of crude product. The products were
subjected to column chromatography on SiO2,
gradient elution with pentane ethyl ether mixture,
ether content from 0 to 30%. We isolated 0.036 g of
compound XIII, 0.018 g of compound XIV, and
0.10 g of unreacted epoxide III.
The NMR spectra were registered from mix-
tures with one or another isomer prevailing.
1H NMR spectrum of (2R,5S)-5-(1-hydroxy-1-methyl-
ethyl)-2-methyltetrahydrofuran-2-acetaldehyde(IX)( ,
ppm, J, Hz): 1.05 s, 1.14 s (C10H3, C11H3), 1.27 s
(C8H3), 1.70 1.95 m (2H3, 2H4), 2.00 br.s (OH),
2.49 d.d (H6, J6,6 15, J6,7 3) and 2.54 d.d (H6 , J 15,
J6 ,7 3) AB system, 3.72 m (H5), 9.72 t (H7, J 3).
1H NMR spectrum of (2S,5R)-5-(1-hydroxy-1-methyl-
ethyl)-2-methyltetrahydrofuran-2-acetaldehyde (X) ( ,
ppm, J, Hz): 1.02 s, 1.14 s (C10H3, C11H3), 1.31 s
(C8H3), 1.70 2.00 m (2H3, 2H4), 2.22 br.s (OH),
2.53 d (2H6, J6,7 3), 3.73 m (H5), 9.76 t (H7, J 3).
4,8,8-Trimethyl-7,9-dioxabicyclo[4.2.1]non-4-
ene (XIII). 1H NMR spectrum ( , ppm, J, Hz):
1.22 s, 1.32 s (C10H3, C11H3), 1.71 d (C9H3, J9,2
1.5), 1.81 m (H5), 1.88 m (H5 ), 2. 18 d.d.d.d (H4,
J4,4 16, J4,5 7.5, J4,5 4.5, J4,2 1) and 2.34 d.d.d.d.q
(H4 , J 16, J4 ,5 9.0, J4 ,5 4.5, J4 ,2 1.5, J4 ,9 1)
AB system, 3.91 d.d (H6, J6,5 6, J6,5 4), 5.38 d (H1,
J1,2 4), 5.48 m (H2, J2,1 4, J2,9 1.5, J2,4 1.5, J2,4 1).
Reaction of epoxides III and IV mixture with a
system acetone water H2SO4. To 1.88 ml of the
mixture acetone water H2SO4 (40: 6: 1 by volume)
was added 0.4 g of epoxides III, IV mixture (1: 1).
In 1 h the reaction mixture was washed with a saturat-
ed solution of Na2CO3, the reaction products were
extracted into ethyl ether. The weight of crude pro-
duct was 0.22 g. The content of the main reaction
products (by GLC data) as a function of the reaction
duration is indicated in Table 1. The products were
subjected to column chromatography on SiO2,
gradient elution with hexane ethyl ether mixture,
ether content from 0 to 90%. We isolated 0.066 g of
compounds IX and X mixture in 1: 2 ratio (GLC),
and 0.042 g of compounds XI and XII mixture in
1.4 : 1 ratio (NMR), compounds were unstable and
tarring occurred at room temperature. Compounds XI
and XII mixture. Found:[M]+ 226.11509. C13H22O3.
Calculated M 226.11512. 1H NMR spectrum of
(E)-3,7-dimethyl-6,7-isopropylidenedioxy-2-octenal
Found [M]+ 168.11470. C10H16O2. Calculated M
168.11502. 2,2,6-Trimethyl-3,9-dioxabicyclo[4.2.1]-
non-4-ene (XIV). 1H NMR spectrum ( , ppm, J,
Hz): 1.15 s, 1.30 s (C9H3, C10H3), 1.37 s (C11H3),
1.60 m and 1.89 m (2H7), 1.92 2.08 m (2H8),
3.97 d.d (H1, J1,8k 8.5, J1,8h 4), 4.55 d (H5, J5,4 8),
5.76 d (H4, J 8). Found [M]+ 168.11461. C10H16O2.
Calculated M 168.11502.
Isomerization of the epoxides III and IV mix-
ture on clay. To 0.50 g of clay in 8 ml of dried
CH2Cl2 was added at stirring 0.30 g of epoxides III
and IV mixture (1: 1) in 2 ml of CH1Cl2. After 5 min
of stirring the catalyst was filtered off and washed
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

TRANSFORMATIONS OF 6,7-EPOXY DERIVATIVES
1603
with ethyl ether. The solvent was removed from the
combined organic solution to afford 0.26 g of crude
product. The products were subjected to column
chromatography on SiO2, gradient elution with
pentane ethyl ether mixture, ether content from 0 to
30%. We isolated 0.043 g of compound XIII,
0.010 g of compound XIV, and 0.09 g of unreacted
epoxide III.
spectra were recorded for the mixture of compounds
1
XVI and XVII. H NMR spectrum of compound XVI
( , ppm, J, Hz): 1.063 d (C7H3, C10H3, J 7), 1.67 d
(C9H3, J9,1 1.5), 2.23 t.d (2H3, J3,4 8, J3,1 1.2),
2.54 t (2H4, J 8), 2.57 septet (H6, J 7), 6.95 m (H1, J
1
1.5, 1.2), 8.01 s (H8). H NMR spectrum of com-
pound XVII ( , ppm, J, Hz): 1.064 d (C7H3, C10H3,
J 7), 1.62 d (C9H3, J9,1 1.5), 2.36 br.t (2H3, J3,4 8),
2.52 t (2H4, J 8), 2.58 septet (H6, J 7), 6.91 m (H1),
8.00 s (H8). Found [M CO]+ 156.11493. C9H16O2.
Calculated [M CO] 156.11502.
Isomerization of the epoxides III and IV mix-
ture on solid superacid TiO2/SO24 . To 0.40 g of
sulfated titanium oxide in 10 ml of dried CH2Cl2 was
added at stirring 0.40 g of epoxides III amd IV mix-
ture (1: 1) in 5 ml of CH2Cl2. After 10 min of stirring
the catalyst was filtered off and washed with ethyl
ether. The content of the main products (by GLC
data) is indicated in Table 1. On removing the solvent
we obtained 0.36 g of crude product. The products
were subjected to column chromatography on SiO2,
gradient elution with hexane ethyl ether mixture,
ether content from 0 to 50%. From the reaction mix-
ture were separated the following substances: 0.11 g
of compounds VII and VIII mixture, 0.09 g of com-
pounds IX and X mixture, and 0.03 g of compound
XV as an isomer mixture in 4: 1 ratio.
2,6-Dimethyl-5-oxoheptanal (XVIII). 1H NMR
spectrum ( , ppm, J, Hz): 1.04 d (C7H3, C9H3, J 7),
1.07 d (C8H3, J8,2 7), 1.63 d.t.d (H3, J3,3 14, J3,4 7,
J3,2 6), 1.90 d.t.d (H3 , J 14, J3 ,4 7, J3 ,2 7),
2.32 d.q.d.d (H2, J 7, 7, 6, J2,1 2), 2.46 m (2H4),
2.54 septet (H6, J 7), 9.56 d (H1, J 2). Found [M]+
156.11493. C9H16O2. Calculated M 156.11502.
Reaction of citronellal (II) with peracetic acid.
A mixture of 2.50 g of compound II, 33 ml (0.028
mol) of CH3COOOH solution in CH2Cl2, and 6 g of
anhydrous Na2CO3 was vigorously stirred for 1 h.
The peracetic acid was preliminary prepared by
extraction from the mixture of 200 ml CH3COOH,
200 ml of 30% H2O2, and 10 ml of H2SO4, and its
concentration was determined by iodometry. In 1 h
the reaction mixture was treated with saturated solu-
tion of Na2CO3, washed with water till neutral, and
dried on Na2SO4. The isolated product of 1.38 g
contained compounds II, XX, and XIX in 1: 1: 6
ratio. By column chromatography on SiO2 (gradient
elution with a mixture hexane ethyl ether, the latter
from 0 to 30%) was isolated 0.13 g of unreacted
aldehyde II. 0.22 g of alcohol XX, and 0.75 g of
epoxides XIX as a mixture of diastereomers XIXa,
XIXb in a ratio 2: 1.
5-Isopropenyl-2-methyltetrahydrofuran-2-acet-
1
aldehyde (XV). H NMR spectrum of the prevailing
isomer( , ppm, J, Hz):1.31s(C8H3), 1.68br.s (C11H3),
1.70 1.92 m (2H3, H4), 2.03 m (H4 ), 2.51 d.d (H6,
J6,6 15, J6,7 3) and 2.55 d.d (H6 , J 15, J6 ,7 3) AB
system, 4.31 br.d.d (H5, J5,4 8, J5,4 6.5), 4.73 m
(H10, J10,10 2, J10,11 1.5, J10,5 1), 4.94 m (H10 , J 2,
J10 ,5 1, J10 ,11 1), 9.76 t (H7, J 3). Found [M]+
168.11461. C10H16O2. Calculated M 168.11502.
Transformation of epoxides V, VI in HSO3F
SO2FCl at 115 C. To a solution of 3.48 g (2 ml)
of HSO3F in 8 ml of SO2FCl was added at 115 C
a solution of 0.42 g of epoxides V, VI mixture (with
the ratio of E40 and Z isomers 2: 1) in 2 ml of
CH2Cl2. The reaction mixture was vigorously stirred
for 5 min at the same temperature, and then poured
into 35 ml of a mixture of methanol with ethyl ether.
Yield of the crude reaction product 0.26 g. GLC
analysis showed that the mixture consisted of com-
pounds XVIII. XVI, and XVII at a ratio 4: 2: 1. By
column chromatography on SiO2 (gradient elution
with a mixture pentane ethyl ether, the latter from 0
to 30%) we isolated 0.1 g of compound XVIII and
0.09 g of compounds XVI and XVII mixture in 1.3 : 1
ratio.
1
3,7-Dimethyl-6,7-epoxyoctanal (XIX). H NMR
spectrum of prevailing isomer A ( , ppm, J, Hz):
0.91 d (C9H3, J9,3 6.5), 1.16 s, 1.20 s (C8H3,
C10H3), 1.31 1.50 m (2H4, 2H5), 2.03 m (H3),
2.16 d.d.d (H2, J2,2 16.5, J2,3 8, J2,1 2.5), 2.33 d.d.d
(H2 , J 16.5, J2 ,3 6, J2 ,1 2), 2.53 t (H6, J6,5 6),
1
9.65 d.d (H1, J 2.5, 2). NMR spectrum H of minor
isomer B ( , ppm, J, Hz): 0.90 d (C9H3, J9,3 6.5),
1.15 s, 1.20 s (C8H3, C10H3), 1.31 1.50 m (2H4,
2H5), 2.03 m (H3), 2.17 d.d.d (H2, J2,2 16.5, J2,3 8,
J2,1 2.5), 2.31 d.d.d (H2 , J 16.5, J2 ,3 6, J2‘,1 2),
2.53 t (H6, J6,5 6), 9.65 d.d (H1, J 2.5, 2). Found
[M]+ 170.11509. C10H18O2. Calculated M 170.11512.
The mixture of (E)- (XVI) and (Z)- (XVII)
1
2,6-dimethyl-5-oxo-1-heptenyl formates. H NMR
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

1604
YAROVAYA et al.
Transformation of epoxides XIX in HSO3F
2.5) and 2.35 d.d.d (H2 , J 16.5, J2 ,3 6, J2 ,1 2) AB
system, 2.40 m (2H5), 2.53 septet (H7, J 7), 9.69 d.d
SO2FCl. To a solution of 2.61 g (1.5 ml) of HSO3F
in 7 ml of SO2FCl was added at 105 C a solution of
0.30 g of isomer mixture of epoxides XIX in 2 ml of
dried CH2Cl2. The reaction mixture was vigorously
stirred for 5 min at the same temperature, and then
poured into 30 ml of a mixture of methanol with ethyl
ether (5: 2 by volume). The reaction products were
extracted into ethyl ether, the solution was dried with
MgSO4. We isolated 0.25 g of mixture of compounds
XXI and XXII. By column chromatography on SiO2
with gradient elution with hexane containing from 0
to 5% of ethyl ether was isolated 0.06 g of compound
XXI and 0.01 g of compound XXII.
(H1, J 2.5, 2). Found [M]+ 170.11509. C10H18O2.
Calculated M 170.11512.
3,7-Dimethyl-6,7-isopropylidenedioxyoctanal
(XXVI). The NMR spectra of compound XXVI are
presented without assignment to one or another iso-
mer for we failed to isolate them as individual com-
pounds or at least with the prevalence of one isomer
( , ppm, J, Hz): 0.94 d, 0.95 d (2C15H3, J 6.5),
1.01 s (6H) and 1.16 s (6H, 2C11H3 and 2C12H3),
1.23 s (6H) and 1.31 s (6H, 2C13H3 and 2C14H3),
2.05 m (2H8), 2.19 d.d.d (J 16, 8, 2) and 2.20 d.d.d
(2H9, J9,9 16, J9,8 8, J9,10 2), 2.36 d.d.d (J 16, 5.5,
2) and 2.38 d.d.d (2H9 , J 16, J9 ,8 5.5, J9 ,10 2),
3.52 d.d (J 9, 3.5) and 3.53 d.d (2H5, J5,6 9, J5,6
3.5), 9.69 d.d (2H10, J 2, 2). Found: [M]+
216.11512. C13H24O3. Calculated: M 216.11525.
2,6-Dimethyl-8,8-dimethoxyoctan-3-one (XXI).
1H NMR spectrum ( , ppm, J, Hz): 0.87 d (C10H3,
J10,6 6.5), 1.04 d (C1H3, C9H3, J 7), 1.33 d.d.d (H7,
J7,7 13, J7,6 7, J7,6 5), 1.35 m (H5), 1.50 m (H6),
1.52 1.62 m (H5 , H7 ), 2.40 m (2H4), 2.55 septet
(H2, J 7), 3.25 s and 3.26 s (2 OCH3), 4.39 d.d (H8,
J8,7 7, J 5). Found [M OCH3]+ 185.11509.
C11H21O2. Calculated [M OCH3] 185.11512.
Isomerization of epoxides XIX on zeolite- . To
0.60 g of calcined zeolite in 8 ml of dry CH2Cl2 was
added 0.40 g of epoxides XIX in 2 ml of CH2Cl2.
After 10 mi of stirring the mixture was filtered, the
catalyst was washed with ethyl ether. On removing
the solvents we obtained 0.31 g of products. By
column chromatography on SiO2 with gradient elu-
tion with hexane containing from 0 to 30% of ethyl
ether was isolated 0.043 g of compound XXVII as
a mixture of diastereomers in 2: 1 ratio, 0.05 g of
compound XXV, and 0.09 g of initial epoxides XIX.
4-Methyl-2-methoxy-7-(1-methoxy-1-methyl-
ethyl)-1-oxacycloheptane (XXII). 1H NMR spec-
trum ( , ppm, J, Hz): 0.91 d (C9H3, J9,4 6.5), 1.08
m (H3), 1.10 s and 1.16 s (C11H3, C12H3), 1.36 m
and 1.82 m (2 H6) 1.54 m and 1.78 m (2H5), 1.62 m
(H4), 1.76 br.d.d (H3 , J3 ,3 13.5, J3 ,2 5), 3.18 s
(OC13H3), 3.36 s (OC8H3), 3.63 br.d (H7, J7,6 10),
4.61 d.d (H2, J2,3 9, J 5). Found [M OCH3]+
185.11509. C11H21O2. Calculated [M OCH3]
185.11512.
4,8,8-Trimethyl-7,9-dioxabicyclo[4.2.1]nonane
1
(XXVII). H NMR spectrum of prevailing isomer ( ,
ppm, J, Hz): 0.89 d (C9H3, J9,3 7), 1.21 s and 1.30 s
(C10H3, C11H3), 1.29 m (H2), 1.39 m (H4), 1.63
1.79 m (H4 , 2H5), 1.91 m (H3), 1.97 m (H2 , J2 ,2
13.5, J2 ,3 6, J2 ,1 4.5, J2 ,4 1.5), 3.92 br.d (H6, J6,5
Transformations of epoxides XIX in a system
acetone water H2SO4. To 0.94 ml of the mixture
acetone water H2SO4 (40: 6: 1 by volume) was
added 0.29 g of epoxides XIX. After 10 min the
reaction mixture was treated with saturated Na2CO3
solution, the reaction products were extracted into
ethyl ether, and the extract was dried with MgSO4.
On removing ether we obtained 0.126 g of substance.
By column chromatography on SiO2 with gradient
elution with hexane containing from 0 to 10% of
ethyl ether was isolated 0.026 g of compound XXV
and 0.06 g of compound XXVI as a mixture of di-
astereomers in 1: 1 ratio.
3,7-Dimethyl-6-oxooctanal (XXV). 1H NMR spec-
trum ( , ppm, J, Hz): 0.93 d (C9H3, J9,3 6.5), 1.05d
(C8H3, C10H3, J 7), 1.44d.t.d (H4, J4,4 14, J4,5 7.5,
J4,3 6.5), 1.57 d.t.d (H4 , J 14, J4 ,5 7, J4 ,3 6),
2.00 m (H3), 2.21 d.d.d (H2, J2,2 16.5, J2,3 7.5, J2,1
1
4), 5.42 d (H1, J 4.5). H NMR spectrum of minor
isomer ( , ppm, J, Hz): 0.93 d (C9H3, J9,3 7), 1.25 s
and 1.30 s (C10H3, C11H3), 1.47 m (2H4), 3.94 d.d
(H6, J6,5 8, J6,5 2), 5.47 t (H1, J1,2 2); the signals of
the other protons coincide with those of the main
isomer. Found M 170.11468. C10H16O2. Calculated
M 170.11504.
ACKNOWLEDGMENT
The authors are grateful to the Russian Foundation
for Basic Research for access to STN database (grant
no. 00-030327721) through the STN-Center of Novo-
sibirsk Institute of Organic Chemistry.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

TRANSFORMATIONS OF 6,7-EPOXY DERIVATIVES
1605
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