Intramolecular cyclization of alicyclic 1,5-di-and 1,3,5-triketones

Article abstract of DOI:10.1023/A:1013115625249

On a series of 44 alicyclic 1,5-di-and 1,3,5-triketones was studied the influence of various structural factors (size of the 5-7-membered ring, positions of the substituents) on the capability for intramolecular aldol condensation and on its direction. The most prone to this reaction are compounds possessing a 6-membered cycle and a substituent in the β-methylene bridge. The substituent in α-position to one of the carbonyl groups can affect the reaction in two ways depending on the degree of shielding of this position.

Full text of DOI:10.1023/A:1013115625249

Russian Journal of Organic Chemistry, Vol. 37, No. 8, 2001, pp. 1068 1073. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 8, 2001,
pp. 1126 1132.
Original Russian Text Copyright
2001 by Akimova, Ivanenko, Vysotskii.
Intramolecular Cyclization of Alicyclic 1,5-Di-
and 1,3,5-Triketones
T. I. Akimova, Zh. A. Ivanenko, and V. I. Vysotskii
Far-Eastern State University, Vladivostok, 690600 Russia
Received August 9, 2000
Abstract On a series of 44 alicyclic 1,5-di- and 1,3,5-triketones was studied the influence of various
structural factors (size of the 5 7-membered ring, positions of the substituents) on the capability for
intramolecular aldol condensation and on its direction. The most prone to this reaction are compounds
possessing a 6-membered cycle and a substituent in the -methylene bridge. The substituent in -position to
one of the carbonyl groups can affect the reaction in two ways depending on the degree of shielding of this
position.
The -diketones with methyl, methylene, or
methine group in -position to one of the carbonyl
groups are known for a long time to undergo
cyclization in the presence of bases into -hydroxy-
cyclohexanones.
13-ones
and
2-hydroxy-8-R-tricyclo[7.2.1.02.7
-
]dodecan-12-ones respectively. The effect of the ring
size and of substituents in the cycle and in the alkyl-
idene group connecting the rings (methane fragment)
on the cyclization process was not studied.
We carried out evaluation of the relative capability
for intramolecular cyclization on a series of alicyclic
1,5-diketones Ia XXXVa and 1,5,9-triketones
(XXXVIa XLIVa) (Scheme 1, designation a was
used for the diketo form of the compound, b cor-
responded to its ketol form). The most of the com-
pounds under study were prepared by us or by our
coworkers: compounds I VI, XXXVI XXXVIII
[11], VIII X, XVII, XIX, XX, XXIV, XXV,
XXVII, XLI [18], XIII, XIV [19], XV [20], XVI
[21], XXI [22], XXVI [17], XXIX, XXXIII XXXV
[23], XXX, XXXI [24], XXXIX [16]. Compounds
XXIII, XXXI, XL were first obtained in [15], com-
pounds XVIII, XXII in [25], XI in [26, 27], XII in
[28]. In this study in order to refine some conclusions
we additionally prepared diketones VIIa, XXVIIIa,
and for compounds XXVIIIa, XXXIa was first ob-
served cyclization into ketoles.
An early example of this reaction was contained in
the discussion of Knoevenagel and Rabe that lasted
for 40 years on the nature of the condensation product
of ethyl acetoacetate with formaldehyde: Whether the
substance was methylene bisacetoacetate or the cor-
responding -ketol [1 4]. On development of IR
spectroscopy numerous products of aldehydes con-
denstion with ethyl acetoacetate regarded as cyclic
1,5-diketones were actually proved to be 3-hydroxy-
cyclohexanones [5]. The condensation direction of the
acyclic -diketones was repeatedly subjected to
investigations; for instance, it was demonstrated that
7-alkyl-2,6-heptanediones cyclized mainly at the
methylene and not methyl group [6, 7]. At present
the studies are continued on the stereochemistry of
cyclization [8], on the rate of aldolization of acyclic
-ketones [9], and on the equilibrium position -di-
ketone 3-hydroxycyclohexanone [10].
The intramolecular aldol cyclization to ketols
occurs under treatment of diketone with 1 M solution
of NaOH or KOH in alcohol. The arising ketols in
contrast to the low-melting original diketones are
high-melting (mp 160 180 C) well crystallized com-
pounds that precipitate from the alcoholic solutions.
Some diketones (IIIa VIa, XIa, XIIa) already dur-
ing the synthesis carried out under basic conditions
cyclize at once into ketols IIIb-VIb, XIb, XIIb. As a
rule the heating of ketols results in retroaldol reaction
[11, 29]; however ketols Vb, XIb do not afford the
Yet in the series of alicyclic 1,5-diketones were
studied only condensations of 2,2’-alkylidenedicyclo-
hexanones [11 15] and 2-[2-oxocyclopentylmethyl(or
benzyl)]cyclohexanones [16, 17] that afforded sub-
stituted
2-hydroxy-8-R-tricyclo[7.3.1.02,7]tridecan-
1070-4280/01/3708-1068$25.00 2001 MAIK Nauka/Interperiodica

INTRAMOLECULAR CYCLIZATION OF ALICYCLIC 1,5-DI- AND 1,3,5-TRIKETONES
1069
Scheme 1.
ing 1,5-diketones. Even ketol XIb whose related
diketone was not obtained in reaction with amines
affords reaction product of the diketo form [30].
XXXIIIa, m = 2, R = Ph; XXXIVa, m = 1, R =
H; XXXVa, m = 1, R = Ph.
Let us consider the effect of structural factors on
the cyclization.
(1) The indispensable condition of intramolecular
aldol condensation in 1,5-diketones with 5 7-
membered rings is the presence of at least one cyclo-
hexanone ring. This rule concerns both unsubstituted
and substituted 1,5-diketones. The driving force of
cyclization is apparently the quest of the carbonyl
carbon of the cyclohexane ring for transition in sp3-
hybridized state with decreased number of eclipsed
interactions. Unsubstituted diketones Ia, XXIIa,
XXXIa containing a six-membered ring afford the
corresponding ketols whereas the unsubstituted
diketones with only 5-membered and 7-membered
rings XVIIIa, XXXa, XXXIIa do not react under
the same conditions. Diketone XXIIa that occupies
an intermediate position between diketones Ia and
XVIIIa yields ketol only in the presence of morpho-
line or piperidine, but an alkali shifts the equilibrium
toward diketone [16].
Ia, m = n = 2, R1 = R2 = R3 = H; IIa, R3 = CH3,
R1 = R2 = H; IIIa, R3 = Ph, R1 = R2 = H; IVa,
R3
= = = =
n-CH3O C6H4, R1 R2 H; Va, R3
p-N(CH3)2C6H4, R1 = R2 = H; VIa, R3 = -furyl,
R1 = R2 = H; VIIa, R3 = R1 = H, R2 = benzylidene;
VIIIa, R3 = R1 = H, R2 = 1-cyclohexenyl; IXa, R3 =
H, R1 = R2 = 1-cyclohexenyl; Xa, R3 = H, R1 =
R2 = 1-Cl-cyclohexyl; XIa, R3 = spirocyclohexane;
R1 = R2 = H; XIIa, R3 = spirocyclohexane; R1 =
H, R2 = 1-cyclohexenyl; XIIIa, R3 = CH3, R1 = H,
R2 =
benzylidene; XIVa, R3 = Ph, R1 = H, R2 =
benzylidene; XVa, R3 = Ph, R1 = 1-cyclohexenyl,
R2 = benzylidene; XVIa, R3 = H, R1 = R2 = benz-
ylidene; XVIIa, m = n = 2, R3 = H, R1 = R2 =
cyclohexylidene; XVIIIa, m = n = 1, R3 = R1 =
R2 = H; XIXa, m = n = 1, R3 = R1 = H, R2 =
cyclopentylidene; XXa, m = n = 1, R3 = H, R1 =
R2 = cyclopentylidene; XXIa, m = n = 1, R3 = H,
R1 = R2 = benzylidene; XXIIa, m = 2, n = 1, R3 =
R1 = R2 = H; XXIIIa, m = 2, n = 1, R3 = Ph, R1 =
R2 = H; XXIVa, m = 2, n = 1, R3 = p-CH3OC6H4,
R1 = R2 = H; XXVa, m = 2, n = 1, R3 = H, R1 =
cyclohexenyl, R2 = H; XXVIa, m = 2, n = 1, R3 =
R1 = H, R2 = benzylidene; XXVIIa, m = 2, n = 1,
R3 = R1 = H, R2 = cyclopentylidene; XXVIIIa, m =
2, n = 1, R3 = Ph, R1 = 1-cyclohexenyl, R2 = H;
XXIXa, m = 2, n = 1, R3 = Ph, R1 = H, R2 =
benzylidene; XXXa, m = 3, n = 1, R3 = R1 = R2 =
H; XXXIa, m = 3, n = 2, R3 = R1 = R2 = H;
XXXIIa, m = 3, n = 3, R3 = R1 = R2 = H.
(2) The presence of a substituent in the -methyl-
ene bridge favors the cyclization of diketone into
ketol, and the transformation is the easier the bulkier
is the substituent. In some instances the transforma-
tion occurs already during the synthesis of the di-
ketone. For example, compounds I V can be pre-
pared by condensation of cyclohexanone with ap-
propriate aldehydes in a basic medium [11]. As the
bulk of the substituent R grows, the fraction of ketol
in the reaction product increases. Thus the condensa-
tion of cyclohexanone with formaldehyde gives rise
to diketone Ia with a small impurity (about 5%) of
the corresponding ketol Ib; in condensation with
acetaldehyde in the reaction mixture diketone IIa and
ketol IIb are present in nearly equal amounts, and
with aromatic aldehydes cyclohexanone affords ketols
IIIb VIb. Diketones XXIIIa and XXIVa containing
an aryl substituent in the -position in contrast to
corresponding diketones due to dehydration or
thermal degradation [29]. Yet in solution both forms
are in equilibrium, and in all reactions studied ketols
serve as initial compounds alongside the correspond-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 8 2001

1070
AKIMOVA et al.
ketones that already have substituents in the -posi-
tion at one of the carbonyl groups facilitates their
cyclization into ketols. For instance, in distinction
from diketones VIIIa, XXVa that do not form ketols
compounds XIIa and XXVIIIa with bulky substitu-
ents in the -methylene bridge exist in ketol form:
Compound XIIb forms just in the process of the
synthesis [28], and ketol XXVIIIb is obtained from
diketone at treatment with alkali. As exception may
be cited the diketones with fused benzene ring
XXXIIIa, XXXVa incapable of ketol formation.
(4) 1,5-Diketones XIIIa XVa, XXIXa containing
in the structure simultaneously an arylidene substitu-
ent at CH2 group in the -position and an alkyl or
aryl substituent in the -position with respect to
carbonyl groups are more prone not to aldol condens-
ation but to intramolecular cyclization resulting in
dihydropyrans C [23, 31] (Scheme 2). Apparently the
arylidene subsituent in the molecule A favors enoliz-
ation of the nearest carbonyl group of the cyclanone.
The arising enol B can further transform into semi-
acetal C. However the necessary condition of this
cyclization as show our examples is the presence of
an alkyl or aryl substituent in the general -position.
Diketones VIIa, XVIa, XVIIa, XXVIa, XXVIIa
lacking such substituent and those with five-
membered cycles XIXa XXIa are not inclined to
cyclization in the basic medium.
diketone XXIIa readily transform into the cor-
responding ketols XXIIIb, XXIVb when treated with
alcoholic solution of alkali [17].
(3) The capability for cyclization of alicyclic
1,5-diketones having substituents in the -position
with respect to carbonyl groups and no substituents
in the -methylene bridge depends on the shielding
extent of the interacting sites. The presence of bulky
substituents in one or another ring prevents the
cyclization of 1,5-diketones. Note for example di-
ketones with such substituents as benzylidene (VIIa
and XXVIa), 1-cyclohexenyl (VIIIa, IXa, XXVa),
1-chlorocyclohexyl (Xa), cyclopentylidene (XXVIIa),
and fused benzene ring (XXXIVa). On the other hand
1,5,9-triketones XXXVIa, XXXIXa, XLIVa that
may be regarded as 1,5-diketones with substituents in
the -position [(2-oxocyclohexyl)methyl or (2-oxo-
cycloheptyl)methyl] readily undergo cyclization when
treated with alkali. Apparently here the sterical factor
is the most important, and since the shielding of the
methylene component in the 1,5,9-triketones is less
than in the mentioned diketones they are still capable
of intramolecular cyclization.
The cyclization is observed not only in the pres-
ence of arylidene substituent but also with a fused
benzene ring. Compound XXXIII in the crystalline
state has a cyclic structure corresponding to the C
form, and in CCl4 and CHCl3 solutions establishes
an equilibrium of diketone and dihydropyran. Com-
pounds of similar structure containing five-membered
rings XXXIVa, XXXVa both in the crystalline state
and in solution are present in diketo form [23]. They
do not yield ketols under treatment with alkaline
solutions.
Introduction of additional substituent into the
-position with respect to carbonyl groups of di-
Scheme 2.
The same facilitating effect of substituents in
the -methylene bridge both on cyclization along
Scheme 1 and 2 suggests that these induce the
1,5-diketones to take the conformation with the reac-
tion sites close in space. The simulation with the use
of models of probable conformations for 1,5-di-
ketones showed that with a bulky substituent R in the
-position the most favorable conformation is E.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 8 2001

INTRAMOLECULAR CYCLIZATION OF ALICYCLIC 1,5-DI- AND 1,3,5-TRIKETONES
1071
Scheme 3.
XXXVIa, m = n = p = 2, R = R = H; XXXVIIa, m = n = p = 2, R = Ph, R = H; XXXVIIIa, m = n= p =
2, R = -furyl, R = H; XXXIXa, m= p= 2, n= 1, R = H; XLa, m= n= p = 1, R = R = H; XLIa, m= n=
R
=
p= 1, R = H, R = cyclopentylidene; XLIIa, m= n= p = 3, R = R = H; XLIIIa, m = p = 3, n = 1, R =
R = H; XLIVa, m = p = 2, n = 3, R = R = H.
The direction of the intramolecular aldol condens-
ation depends on the following factors.
semiacetal G and then into the final reaction product
XXXXIc XXXIXc, XLIVc. The first cyclization
product of 1,5,9-triketones turned out to be com-
pound XXXVIc that previously had been assigned
another structure [32]. Yet later by separation of the
intermediate cyclization products of triketone
(1) In alicyclic 1,5-diketones containing alongside
6-membered also 5- and 7-membered rings the cyclo-
hexanone ring plays the part of the carbonyl
component, and the cyclopentanone and cyclo-
heptanone rings furnish methylene component, i.e.,
in the corresponding ketols m = 2 and a n = 1, 3
(Scheme 1). This behavior is observed with diketones
XXIIa XXIVa, XXVIIIa, XXXIa and triketones
XXXIXa, XLIVa. In diketone XXIXa everything
seemingly favors the action of the cyclopentanone
ring as a carbonyl component (phenyl substituent in
the -methylene bridge, no CH2 group in the
-position of the cyclopentanone ring); however this
compound under the synthesis conditions yields at
once the dihydropyran form C. (2) In 1,5,9-triketones
XXXVIa XXXIXa, XLIVa capable of intramole-
cular aldol condensation the cyclization occurs not at
the free methylene group by at methine one. This
cyclization direction was also observed with acyclic
-ketones [6, 7].
1
XXXIXa and proceeding from the data of IR, H and
13
NMR spectroscopy was established the described
above structure of compounds XXXIXc [33] and
XXXVIc [16]. The structure of the latter compound
was solved by X-ray diffraction analysis [34]; it
showed that the tetrahydropyran rings in compound
XXXVIc existed in the boat conformation.
The rules revealed for alicyclic 1,5-diketones hold
also in the 1,5,9-triketone series. Triketones XLa,
XLIa, XLIIIa lacking the cyclohexanone rings do
not form intramolecular cyclization products when
treated with alkali. In triketones XXXIXa and XLIVa
containing alongside 6-membered ring also 5- and
7-membered rings the carbonyl component is also the
cyclohexanone ring, and those of cyclopentanone and
cycloheptanone provide methylene component.
Intramolecular aldol condensations in 1,5,9-tri-
ketones begin as an interaction between two rings to
form ketols F like those arising from 1,5-diketones.
The cyclization occurs at methine group providing a
quaternary carbon atom in the compound; the latter
atom is not bonded to oxygen. This structuer is
impossible for the other directions of aldol condens-
ation. The arising ketol F converts successively into
The structure of compounds obtained VIIa,
1
XXVIIIa,b, XXXIb was confirmed by IR, H and
13C NMR, and mass spectra.
Absorption bands frequencies for carbonyls in 6-
and 7-membered rings are close in value: according to
various publications their difference not exceeds
1
8 10 cm . To reveal from which ring originates the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 8 2001

1072
AKIMOVA et al.
carbonyl group remaining in ketol XXXIb we
registered under equal conditions the IR spectra of
the original cyclohexanone, cycloheptanone, and the
products obtained XXXIa, XXXIb. Under the same
conditions were measured the IR spectra of diketone
Ia and its ketol Ib to estimate the effect of the rigid
ketol structure and of the size of 1 7-membered ring
on the absorbance of the carbonyl group:
Cyclohexanone Cycloheptanone
1705.6 1697.0
XXXIa
1706.6, 1695.7
XXXIb
1696.4
Ia
Ib
1
(C= O), cm
1706.8
1708.6
1
(OH), cm
3448, 3588
3410, 3585
The data obtained unambiguously indicate that in
ketol XXXIb the carbonyl group of cycloheptanone
is retained; this is also confirmed by 13C NMR
spectra.
(11)[M]+ , 278 (2) [M H2O]+ , 199(37) [M C6H9O]+ ,
186 (100) [C6H8OCHPh]+ , 171 (12), 141 (21), 129
1
(37), 115 (62), 91 (46). H NMR spectrum ( , ppm)
contained a group of multiplets in 1.2 3.0 (18H)
region and a group of multiplets at 7.3 7.4 (6H,
=CH) 13C NMR spectrum in CDCl3 ( C, ppm)
showed the presence of two isomers (apparently, treo-
and erithro-forms), all the signals were doubled save
broadened signals at 22.5 and 28.7 ppm). Signals of
methylene group carbons: 22.5, 24.7, 25.0, 28.0,
28.2, 28.7, 29.7, 30.1, 31.0, 31.7, 34.4, 34.8, 41.9,
42.3; signals of methine carbons appeared as two
pairs of lines: 46.3, 48.0 and 47.2, 49.1 with
intensity ratio 4: 5; 128.2, 130.0, 134.4, 134.7
(=_CH); 135.8, 137.5, 137.7 (=C); 204.2, 205.0,
213.3, 213.6 (_C=O). Found, %: C 81.12; H 8.23.
C20H24O2. Calculated, %: C 81.08; H 8.11.
In the mass spectra of the compounds obtained is
clearly seen the retro-Michael decomposition char-
acteristic of 1,5-diketones.
EXPERIMENTAL
IR spectra (from KBr pellets) were recorded on
Spectrum BX-II (Perking Elmer) instrument, mass
spectra were measured on HÞ 5972 MSD/HÞ 5890
series II GC (Hewlet-Packard) device. 1H and
13C NMR spectra were registered in CDCl3 on
spectrometer Bruker AC-250 at operating frequencies
250 MHz (1H) and 62.9 MHz (13C), internal reference
TMS. The assignment of signals was done with the
use of off-resonance technique.
2-[ -(2-Oxocyclopentyl)benzyl]-6-(1-cyclohexen-
yl)cyclohexanone (XXVIIIa) (procedure [15] and
2-hydroxy-3-(1-cyclohexenyl)-8-phenyltricyclo-
[7.2.1.02,7]dodecan-12-one (XXVIIIb). A mixture
of 2 g (0.0075 mol) of 2-benzylidene-6-(1-cyclo-
hexenyl)cyclohexanone, 1.15 g (0.0075 mol) of
1-cyclopentenylmorpholine, and 6 ml of anhydrous
dioxane was refluxed for 40 h. The reaction progress
was monitored by TLC. The cooled reaction mixture
was diluted with water (15 ml), acidified to pH 3 4
with diluted (1: 5) hydrochloric acid, the reaction
product was extracted into ether, the extract was
washed with water till pH 7, and dried with Na2SO4.
The ether was evaporated on a water bath, and the
residual solvent was removed in a vacuum of oil
pump. We obtained 2.48 g (95%) of resinous sub-
stance. Further separation of the target product was
carried out in two ways. (a) 0.48 g of the resinous
substance was dissolved in 0.5 ml of 1 M NaOH
alcoholic solution. In 10 min crystallized ketol
XXVIIIb. Yield 0.41 g (85%).
2-Benzylidene-6-(2-oxocyclohexylmethyl)-cyclo-
hexanone (VIIa) (procedure [25]). A mixture of 3 g
(0.016 mol) of 2-benzylidenecyclohexanone, 0.6 g
(0.02 mol) of paraformaldehyde, 1.62 g (0.02 mol)
of dimethylamine hydrochloride, 10 ml of 2-propanol,
and 0.02 ml of concn HCl was refluxed at stirring
for 20 min. The solvent was distilled off from the
crystallized light-yellow precipitate, the latter (5 g)
was dissolved in 10 ml of water, and the organic com-
pounds were extracted with ether. To the water layer
was added 40% solution of NaOH till alkaline pH,
the Mannich base was extracted with ether, the extract
was dried with Na2SO4, and the ether was distilled
off. To the residue (4.5 g), Mannich base of 2-benzyl-
idenecyclohexanone, was added 2 g (0.02 mol) of
cyclohexanone, and the mixture was heated for 15 h
on a sand bath at 180 200 C. After cooling the reac-
tion mixture was distilled in a vacuum of oil pump to
obtain 2.2 g (46%) of diketone VIIa, bp 230 235 C
(4 mm Hg). The compound crystallized at cooling,
mp 88 90 C (from ethanol). On mixing with 1 M
alcoholic solution of NaOH diketone VIIa did not
(b) 1 g of resinous substance was mixed with 3 ml
of hexane, the insoluble residue (0.57 g) was re-
crystalized from ethanol. From the ethanol solution
separated 0.21 g of precipitate comprising a mixture
of compounds XXVIIIa and XXVIIIb, and from the
1
change. IR spectrum, cm : 1704, 1679 (C=O),
1604, 1490 (Ph). Mass spectrum, m/z (Irel, %): 296
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 8 2001

INTRAMOLECULAR CYCLIZATION OF ALICYCLIC 1,5-DI- AND 1,3,5-TRIKETONES
1073
filtrate was additionally isolated 0.1 g of diketone
XXVIIIa. The obtained mixture (0.21 g) was dis-
solved in 1 ml of 1 M NaOH solution in ethanol, and
in 2 h was filtered off 0.17 g of ketol XXVIIIb.
pp. 501 504.
12. Colonge, J., Dreux, J., and Deplace, H., Bull. Soc.
Chim., 1956, no. 11 12, pp. 1635 1640.
13. Plesek, J. and Munk, P., Chem. Listy, 1957, vol. 51,
pp. 633 638.
Retroaldol reaction of ketol XXVIIb. In a sealed
capillary 50 mg of ketol XXVIIIb was heated for
15 min to 190 C. The melt on cooling was recrystal-
lized from ethanol water mixture (3: 1) to obtain
40 mg of diketone XXVIIIa (identified by TLC, IR
spectrum and melting point of the compound mixed
with an authentic sample).
14. Plesek, J. and Munk, P., Coll. Chem. Commun.,
1957, vol. 22, pp. 1596 1602.
15. Birkofer, L., Kim, S.M., and Engels, H.D., Chem.
Ber., 1962, vol. 95, no. 6, pp. 1495 1504.
16. Akimova, T.I., Kosenko, S.V., and Tilichenko, M.N.,
Zh. Org. Khim., 1991, vol. 27, no. 12,
pp. 2553 2560.
2-Hydroxytricyclo[7. 4. 1. 02,7]tetradecanone
(XXXIb). To 0.5 g of diketone XXXIa was added
0.5 ml of 1 M NaOH ethanol solution, and the yellow
mixture was left standing at 0 C. 3 days later crystal
precipitate was separated. Yield of ketol XXXIb
0.33 g (66%), mp 118 120 C (from hexane). IR
spectrum see above. Mass spectrum, m/z (Irel, %):
222 (59.5) [M]+ , 204 (7.3) [M H2O]+ , 125 (47.2)
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26. Pettit, G.R. and Thomas, E.G., Chem. Ind., 1963,
vol. 44, pp. 1758 1760.
27. Rollin, P., Bull. Soc. Chim., 1973, no. 4,
pp. 1509 1514.
28. Rollin, P., Bull. Soc. Chim., 1973, no. 5,
pp. 1806 1810.
29. Vysotskii, V.I., Vershinina, N.V., and Tilichen-
ko, M.N., Dep. VINITI., no. 920-74; Ref. Zh. Khim.,
1974, 17Zh 227.
+
+
[C7H11OCH2] , 124 (99.1) [M C6H9O] , 112 (99.1)
+
+
[C6H9OCH2 and C7H11O] , 98, 100 [C6H9O] .
1H NMR spectrum ( , ppm, J, Hz): 1.2 2.1 m
(21H), 2.44 m (1H, C9H), 2.75 t (1H, C1H, J 5).
13C NMR spectrum ( C, ppm): 20.7, 24.9, 25.9,
26.1, 26.3, 28.5, 32.7, 34.9, 35.0 (9C_ H2); 35.7,
48.1 (C7, C9); 61.0 (C1), 76.1 (C2), 215.4 (C14). [To
compare: 13C NMR spectrum ( C, ppm) of diketone
XXXIa contains signals from two carbonyl groups at
212.3 (in cyclohexanone) and 215.3 (in cyclohepta-
none).] Found, %: C 75.32; H 9.83. C14H22O2.
Calculated, %: C 75.68; H 9.91.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 8 2001