Reaction of sabinene with aldehydes in the presence of montmorillonite K10 clay

Article abstract of DOI:10.1134/S1070428010070079

Transformations of sabinene catalyzed by montmorillonite K10 clay were studied. The main reaction paths were found to be oligomerization and isomerization. The reaction of sabinene with crotonaldehyde gave rise to several polyfunctional heterocyclic compo

Full text of DOI:10.1134/S1070428010070079

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 7, pp. 1002–1005. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © I.V. Il’ina, D.V. Korchagina, K.P. Volcho, N.F. Salakhutdinov, G.A. Tolstikov, 2010, published in Zhurnal Organicheskoi Khimii,
2010, Vol. 46, No. 7, pp. 1006–1009.
Reaction of Sabinene with Aldehydes in the Presence
of Montmorillonite K10 Clay
I. V. Il’ina, D. V. Korchagina, K. P. Volcho, N. F. Salakhutdinov, and G. A. Tolstikov
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
e-mail: volcho@nioch.nsc.ru
Received July 1, 2009
Abstract—Transformations of sabinene catalyzed by montmorillonite K10 clay were studied. The main reac-
tion paths were found to be oligomerization and isomerization. The reaction of sabinene with crotonaldehyde
gave rise to several polyfunctional heterocyclic compounds.
DOI: 10.1134/S1070428010070079
The use of natural montmorillonite askanite–ben-
tonite clay and its commercially available analog K10
as catalysts in the transformations of monoterpenoids
of the pinane, carane, and para-menthane series makes
it possible to obtain new optically active polyfunc-
tional heterocyclic compounds [1, 2]. These catalysts
not only ensure milder reaction conditions and higher
yield of products but also enhance regio- and stereo-
selectivity of the process due to definite spatial orienta-
tion of the reacting molecules, especially of those
possessing several reaction centers. In the present work
we examined for the first time the reactivity of sabi-
nene (I) (monoterpene of the thujane series) in the
presence of montmorillonite K10 clay.
α- and γ-terpinenes II and III, terpineol, and p-cymene
(IV) [4]. When a solution of sabinene (I) in methylene
chloride was kept for 30 min in the presence of K10,
a complex mixture of products was formed. According
to the GC–MS data, this mixture contained dimeriza-
tion (~53%, more than 20 compounds) and trimeriza-
tion products (~24%, more than 10 compounds), α-
and γ-terpinenes II and III (2 and 5%, respectively),
p-cymene (IV, 2%), β-phellandrene (V, 1%), and ter-
pinolene (VI, 1%) (Scheme 1).
We previously [2] obtained a series of heterocyclic
compounds VIII–X by reaction of crotonaldehyde
with 4-hydroxymethylcar-2-ene (VII) which, like sabi-
nene (I), possesses a double bond conjugated with
cyclopropane ring. The formation of compounds VIII–
X was rationalized by a mechanism involving pro-
tonated aldehyde as electrophilic species. Addition of
the protonated aldehyde at the double bond of terpen-
oid VII gave compounds VIII and IX with an 8-oxa-
bicyclo[4.3.0]nonane skeleton, while the addition at
the cyclopropane ring led to the formation of tricyclic
derivative X (Scheme 2).
Sabinene (I) is a natural monoterpene having a bi-
cyclo[3.1.0]hexane skeleton; it is a component of
juniper essential oils [3]. Chemical transformations of
sabinene (I) were reported in a few publications,
whereas its behavior under conditions of heterogene-
ous catalysis is almost unknown. Compound I in the
presence of acids generally undergoes isomerization
into compounds having a para-menthane skeleton:
Scheme 1.
Me
Me
Me
CH2
Me
CH2
K10
Dimers
Trimers
+
+
+
+
+
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
I
II
III
IV
V
VI
1002

REACTION OF SABINENE WITH ALDEHYDES
1003
Scheme 2.
Me
Me
CHOH
Me
a
OH
OH
b
Askanite–bentonite
CHO
+
Me
Me
Me
Me
Me
O
VII
Me
Me
Me
Me
O
+
a
Me
Me
Me
Me
VIII
IX
Me
O
Me
Me
Me
b
Me
O
X
In the present work we made an attempt to perform
reactions of monoterpene I with aldehydes in the
presence of K10 clay. Sabinene (I) failed to react
with salicylaldehyde, vanillin, and 4-methoxy- and
4-fluorobenzaldehydes over K10. In these cases, only
isomerization and oligomerization of the initial com-
pound occurred. We were the first to obtain bicyclic
compounds XI (1.8%) and XII (1.3%) by reaction of
sabinene (I) with crotonaldehyde in the presence of
K10. However, the main reaction path (as before)
involved dimerization and trimerization of the initial
olefin (Scheme 3).
A whose subsequent intramolecular heterocyclization
and isomerization lead to product XI. An alternative
pathway is likely to involve carbocation B as electro-
philic species, whereas crotonaldehyde acts as nucleo-
phile. Cation B is generated by protonation and sub-
sequent isomerization of olefin I. Analysis of the
proposed mechanisms shows that the formation of
compound XII should be accompanied by racemiza-
tion. The facts that compound XI is optically active
and that product XII is a racemate count in favor of the
mechanisms shown in Scheme 4.
Despite the presence of similar structural frag-
ments, the direction of the intermolecular transforma-
tion of sabinene (I) with crotonaldehyde over K10 clay
considerably differs from analogous transformation of
4-hydroxymethylcar-2-ene (VII) [2].
Scheme 4 illustrates possible mechanisms for the
formation of compounds XI and XII. Attack by the
protonated aldehyde on the cyclopropane ring in mole-
cule I at the less sterically hindered side yields cation
Scheme 3.
Hsyn
Me12
CH2
Hanti
Me
8
11
10
Me
Me
O
K10
5
Dimers
Trimers
4
CHO
O
+
+
III, V–VII
+
+
3
Hexo
Me
1
7
2
Me
Me
13
Me9
Me
14
Me
Me15
I
XI
XII
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 7 2010

IL’INA et al.
1004
Scheme 4.
Me
R
CH2
CH2
CH2
Me
HO
RCHOH
O
R
–H+
Me
O
Me
Me
Me
Me
Me
Me
Me
I
A
XI
H+
Me
Me
Me
Me
Me
Me
O
RCHO
–H+
Me
Me
Me
Me
Me
Me
Me
Me
Me
R
O
Me
B
XII
R = (E)-MeCH=CH.
Compound XI was not reported previously, and its
structure was determined on the basis of the 1H and 13C
NMR spectra and high-resolution mass spectra. Deriv-
atives having the same skeleton as in molecule XI but
lacking substituent on C7 were obtained previously
while studying transformations of alcohols of the
carane series in superacidic medium (HSO3F–SO2FCl,
–100°C) [5] and in the presence of natural montmoril-
lonite clay (askanite–bentonite) [6]. Compound XII
was synthesized by us previously via reaction of cro-
tonaldehyde with limonene [7].
The purity of the initial compounds and reaction
products was checked, and the reaction mixtures were
analyzed, by GLC on a Varian Model 3700 chromato-
graph equipped with a flame ionization detector and
a VC-30 quartz capillary column, 15000×0.22 mm;
carrier gas helium, inlet pressure 1 atm. Gas chromato-
graphic–mass spectrometric analysis was performed on
a Hewlett–Packard HP 5890 Series II chromatograph
coupled with a n HP 5971 quadrupole mass-selective
detector (HP-5MS quartz capillary column, 30000×
0.25 mm; carrier gas helium).
Montmorillonite K10 clay (Merck) was calcined for
3 h at 110°C just before use. Methylene chloride was
purified by passing through a column charged with
calcined aluminum oxide. The products were separated
by column chromatography on silicagel (60–200 μm,
Macherey–Nagel). Sabinene (I) with an [α]D20 value of
+43° (c = 1.9, CHCl3) was used.
EXPERIMENTAL
The H and 13C NMR spectra were recorded on
1
a Bruker DRX-500 spectrometer at 500.13 and
125.76 MHz, respectively, using CDCl3–CCl4 (~1:1
by volume) as solvent. The chemical shifts were
measured relative to the residual proton and carbon
signals of the solvent (CHCl3, δ 7.24 ppm; CDCl3,
Reaction of sabinene (I) with crotonaldehyde in
the presence of montmotrillonite K10. A solution of
1 g (14 mmol) of crotonaldehyde was added to a sus-
pension of 4 g of K10 clay in 15 ml of methylene
chloride, a solution of 1 g (7 mmol) of sabinene (I) in
10 ml of methylene chloride was then added dropwise,
and the mixture was stirred for 1 h at room tempera-
ture. The mixture was diluted with 10 ml of diethyl
ether, the catalyst was filtered off, the filtrate was
evaporated, and the residue was subjected to chroma-
tography in a column charged with 10 g of silica gel
δC 76.90 ppm). Signals were assigned using H–1H
1
double resonance, J-modulation (JMOD) with off-
resonance decoupling from protons, and 13C–1H two-
dimensional heteronuclear correlation (direct 13C–1H
1
coupling constants, COSY, JCH = 135 Hz). The high-
resolution mass spectra were obtained on a DFS
Thermo Scientific instrument (direct sample admission
into the ion source, electron impact, 70 eV, a.m.u range
0–500). The optical rotations [α]D were determined on
a polAAr 3005 polarimeter from solutions in CHCl3.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 7 2010

REACTION OF SABINENE WITH ALDEHYDES
1005
using hexan–diethyl ether as eluent (gradient elution,
0 to 10% of diethyl ether). We isolated 0.028 g (1.8%)
of compound XI, 0.019 g (1.3%) of compound XII,
and 0.180 g of a mixture containing (according to the
GC–MS data) ~48% of dimeric products (more than
20 compounds), ~21% of trimeric products (more than
10 compounds), 2% of α-terpinene (II), 5% of γ-terpi-
nene (III), 2% of p-cymene (IV), 1% of β-phelland-
rene (V), and 1% of terpinolene (VI).
7-H also indicates exo orientation of the latter. Found:
m/z 206.1656 [M]+. C14H22O. Calculated: M 206.1665.
2,2,6-Trimethyl-4-[(E)-prop-1-en-1-yl]-3-oxabi-
cyclo[3.3.1]non-6-ene (XII). [α]D20 = 0 (c = 0.8,
CHCl3). The spectral parameters of compound XII
coincided with those reported in [7].
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 7 2010