A Convenient and Stereoselective Method for the Preparation of 2-Substituted 1,3-Alkadienes from 1,2-Disubstituted Cyclopropanols

Article abstract of DOI:10.1055/s-2003-44987

Sulfonates of cis-1,2-disubstituted cyclopropanols are converted into 2-substituted 1,3-alkadienes in moderate to good yields under the action of magnesium perchlorate and triethylamine in diethyl ether. High trans-stereoselectivity was observed for the preparation of the alkadienes with a 1,2-disubstituted double bond. The stereochemical outcome in the reaction is consistent with a concerted reaction mechanism involving an Mg(ClO ₄)₂-initiated cationic cyclopropyl-allyl isomerization of the cyclopropyl sulfonates which is accompanied by a deprotonation.

Full text of DOI:10.1055/s-2003-44987

344
LETTER
A Convenient and Stereoselective Method for the Preparation of 2-Substituted
1,3-Alkadienes from 1,2-Disubstituted Cyclopropanols
P
reparation of 2-S
u
ubstitute
d
1,3
r
-Alkadi
i
enes
f
ro
i
m
1,2-Disub
Y
stituted
C
ycloprop
u
anols . Kozyrkov, Oleg G. Kulinkovich*
Department of Organic Chemistry, Belarusian State University, 4, Skoriny av., Minsk, 220050, Belarus
Fax +375(17)2264998; E-mail: kulinkovich@bsu.by
Received 22 October 2003
In this work we have elaborated a convenient method for
Abstract: Sulfonates of cis-1,2-disubstituted cyclopropanols are
converted into 2-substituted 1,3-alkadienes in moderate to good
yields under the action of magnesium perchlorate and triethylamine
in diethyl ether. High trans-stereoselectivity was observed for the
preparation of the alkadienes with a 1,2-disubstituted double bond.
The stereochemical outcome in the reaction is consistent with a
concerted reaction mechanism involving an Mg(ClO4)2-initiated
cationic cyclopropyl–allyl isomerization of the cyclopropyl
sulfonates which is accompanied by a deprotonation.
the transformation of sulfonates of 1,2-disubstituted cy-
clopropanols into the 2-substituted-1,3-alkadienes, based
on the same mode of cyclopropane ring cleavage.
cis-1,2-Disubstituted cyclopropanols 1 were obtained by
the treatment of appropriate carboxylic esters with an
alkyl magnesium bromide in the presence of titanium(IV)
isopropoxide3,4 and were further smoothly converted into
cyclopropyl sulfonates 2 by a standard procedure
(Scheme 1).5 The interaction of mesylate of 1-benzyl-2-
methylcyclopropanol (2a) with magnesium perchlorate in
diethyl ether gave 2-benzyl-1,3-butadiene (3a) in 40%
yield. The dehydrosulfonation of mesylate 2a proceeded
more effectively in the presence of triethylamine and
crude alkadiene 3a was obtained in 76% yield (see
Table 1, entry 1). However, the product contained near
10% impurities (1H NMR). The product could not be
separated off by column chromatography on silica gel or
alumina.
Key words: cyclopropanols, sulfonates, ring opening, 1,3-dienes,
magnesium perchlorate
Tertiary cyclopropanols are readily available compounds
and their synthetic applications are based mainly on the
ring opening reactions, when one of the bonds adjacent to
the carbinol carbon atom (C1-C2 or C1-C3 bonds in cy-
clopropane ring) undergoes cleavage.1 Recently we dis-
closed a simple and useful procedure for converting
sulfonates of tertiary cyclopropanols into allyl halides un-
der the action of magnesium bromide or some other metal
halides in diethyl ether.2 This reaction includes C2-C3
cyclopropane ring cleavage and proceeds via a cationic
cyclopropyl–allyl rearrangement, which is induced by the
metal halide assisted heterolytic cleavage of the carbon-
oxygen bond in cyclopropyl sulfonates. Transfer of the
halide anion from the Lewis acid further captures the
allylic cation thus formed.
Alkadiene 3a was formed in moderate to good yields and
could be easy purified by column chromatography when
tosylate 2b was used as substrate (entry 2). The reaction
proceeded more clearly and more homogenously in the
mixture of diethyl ether and dichloromethane (3:2) as a
solvent.
Tosylates of the 1-alkyl and 1-haloalkyl substituted cyclo-
propanols 2 also gave the corresponding 1,3-alkadienes in
moderate to good yields (entries 3–8).
Scheme 1
SYNLETT 2004, No. 2, pp 0344–0346
0
2.
0
2.
2
0
0
4
Advanced online publication: 08.12.2003
DOI: 10.1055/s-2003-44987; Art ID: G28303ST.pdf
© Georg Thieme Verlag Stuttgart · New York

LETTER
Preparation of 2-Substituted 1,3-Alkadienes from 1,2-Disubstituted Cyclopropanols
345
Table 1 Yields of 2-Substituted 1,3-Alkadienes in the Reaction of
Cyclopropyl Sulfonates with Mg(ClO4)2 in the Presence of Et3N
Entry Cyclopropyl sulfonatea,b Productc,d
Yield (%)e
76
1
3a
2a
3a
2
70
2b
Scheme 2
3
80
46
45
4
5
In summary, an efficient two-step method for the conver-
sion of readily available tertiary cis-1,2-disubstituted cy-
clopropanols 1 to terminal 2-substituted 1,3-alkadienes 3
has been elaborated. The method is characterized by
high trans-diastereoselectivity toward formation of the
1,3-alkadienes with disubstituted double bond.
6
7
8
65f,g
35f,g
67f,g
Acknowledgment
This work was carried out with support of the INTAS program.
References
a Typical procedure for the preparation of cyclopropyl sulfonates, see
ref.6,
(1) For reviews see: (a) Gibson, D. H.; De Puy, C. H. Chem.
Rev. 1974, 74, 605. (b) Kulinkovich, O. G. Chem. Rev.
2003, 103, 2597.
(2) Kozyrkov, Yu. Yu.; Kulinkovich, O. G. Synlett 2002, 443.
(3) (a) Kulinkovich, O. G.; Sviridov, S. V.; Vasilevskii, D. A.;
Savchenko, A. I.; Pritytskaya, T. S. J. Org.Chem. USSR
(Engl. Transl.) 1991, 27, 250. (b) Kulinkovich, O. G.;
Vasilevskii, D. A.; Savchenko, A. I.; Sviridov, S. V. J. Org.
Chem. USSR (Engl.Transl.) 1991, 27, 1249.
(4) For reviews see: (a) Kulinkovich, O. G.; de Meijere, A.
Chem. Rev. 2000, 100, 2789. (b) Breit, B. J. Prakt. Chem.
2000, 342, 211. (c) Kulinkovich, O. G. Pure Appl. Chem.
2000, 72, 1715.
b Selected data of substituted cyclopropyl sulfonates, see ref.7,
c Typical procedure for the preparation of 2-substituted 1,3-alka-
dienes, see ref.8,
d Selected data of 2-substituted 1,3-alkadienes, see ref.9,
e Isolated yield after column chromatography on silica gel.
f In 1H NMR spectrum the signals of the corresponding Z-isomer were
not observed.
g The stereochemistry of the 1,2-disubstituted double bond was
assigned by the coupling constant of vicinal olefinic protons
(J = 15.6 Hz).
(5) (a) For preparation of mesylates see: Ollivier, J.; Dorizon, P.;
Piras, P. P.; de Meijere, A.; Salaün, J. Inorg. Chim. Acta
1994, 222, 37. (b) For preparation of tosylates see: Fieser, L.
F.; Fieser, M. Reagents for Organic Synthesis, Vol 1.;
Wiley: New York, 1967, 1179.
(6) Typical Procedure: Tosyl chloride (2.86 g, 15 mmol) was
added at once to a solution of 1-benzyl-2-methylcyclo-
propanol (1a, 1.62 g, 10 mmol) in dry pyridine (15 mL) at
0 °C and the mixture was left overnight at r.t. After treatment
with ice water (100 mL) and Et2O (3 × 15 mL), the organic
phase was washed with 5% H2SO4 (15 mL), aq NaHCO3
(2 × 15 mL) and dried with anhyd Na2SO4. After
evaporation of the solvents the residue was purified by
column chromatography on silica gel (eluent benzene) to
give 1.22 g (51%) of tosylate 2b as a colorless oil.
(7) 1H NMR (400 MHz, CDCl3): Entry 2: d = 0.47 (t, J = 6.8
Hz, 1 H), 1.16 (d, J = 6.8 Hz, 3 H), 1.35 (dd, J1 = 10.6 Hz,
J2 = 6.4 Hz, 1 H), 1.52–1.65 (m, 1 H), 2.40 (s, 3 H), 3.05 (d,
J = 16 Hz, 1 H), 3.28 (d, J = 16 Hz, 1 H), 7.22 (d, J = 8 Hz,
2 H), 7.30–7.40 (m, 5 H), 7.62 (d, J = 8 Hz, 2 H). Entry 6:
d = 0.19 (t, J = 6.4 Hz, 1 H), 0.87 (t, J = 7.2 Hz, 3 H), 1.05–
1.40 (m, 16 H), 1.54 (s, 3 H), 2.43 (s, 3 H), 7.31 (d, J = 8 Hz,
2 H), 7.75 (d, J = 8 Hz, 2 H). Entry 8: 0.18 (t, J = 6.8 Hz,
High selectivity toward formation of 1,3-alkadienes with
trans-disubstituted olefinic bonds (entries 6–8) is a re-
markable feature of this reaction. We believe that the
origin of the observed high trans-/cis-stereoselectivity
arises from a concerted mechanism of the reaction and in
this respect there is a formal similarity to the Julia rear-
rangement of secondary cyclopropyl–carbinyl systems to
homoallyl halides.10 The latter transformation was ration-
alized by a concerted mechanism of cyclopropane ring
opening in the most preferable conformation of the start-
ing cyclopropyl carbinol.10c In fact, if concerted mecha-
nism of the dehydrosulfonation of compounds 2 is also
realized, the transition states leading to trans- and cis-iso-
meric 1,3-alkadienes (entries 6–8) can be depicted by the
Newman projection formulas A and B, respectively
(Scheme 2). Non-bonded interactions between hydrogen
atoms on the R1 and R2 groups in tosylates 2 probably
sufficiently destabilize transition state B relative to A,
providing the high trans-stereoselectivity of the reaction.
Synlett 2004, No. 2, 344–346 © Thieme Stuttgart · New York

346
Y. Yu. Kozyrkov, O. G. Kulinkovich
LETTER
1 H), 0.85 (t, J = 7.2 Hz, 3 H), 0.87 (t, J = 7.2 Hz, 3 H), 0.98–
1.10 (m, 1 H), 1.12–1.55 (m, 19 H), 1.80–1.90 (m, 1 H), 2.43
(s, 3 H), 7.31 (d, J = 8 Hz, 2 H), 7.75 (d, J = 8 Hz, 2 H).
(9) 1H NMR (400 MHz, CDCl3): Entry 2: d = 3.59 (s, 2 H), 4.94
(s, 1 H), 5.09 (d, J = 10.8 Hz, 1 H), 5.20 (s, 1 H), 5.27 (d,
J = 17.6 Hz, 1 H), 6.47 (dd, J1 = 17.6 Hz, J2 = 10.8 Hz, 1 H),
7.18–7.34 (m, 5 H). Entry 6: d = 0.92 (t, J = 6.8 Hz, 3 H),
1.20–1.50 (m, 10 H), 1.87 (s, 3 H), 2.14 (m, J = 7 Hz, 2 H),
4.89 (s, 2 H), 5.70 (dt, J1 = 15.6 Hz, J2 = 7 Hz, 1 H), 6.17 (d,
J = 15.6 Hz, 1 H). Entry 8: 0.87 (t, J = 6.8 Hz, 3 H), 0.92 (t,
J = 7.2 Hz, 3 H), 1.25–1.55 (m, 10 H), 2.08 (q, J = 7 Hz, 2
H), 2.19 (t, J = 7.2 Hz, 2 H), 4.85 (s, 1 H), 4.88 (s, 1 H), 5.68
(dt, J1 = 15.6 Hz, J2 = 7 Hz, 1 H), 6.06 (d, J = 15.6 Hz, 1 H).
(10) (a) Julia, M.; Julia, S.; Guegan, S. Y. Bull. Soc. Chim. Fr.
1960, 1072. (b) Julia, M.; Julia, S.; Tchen, S. Y. Bull. Soc.
Chim. Fr. 1961, 1849. (c) Brady, S. F.; Ilton, M. A.;
(8) Typical Procedure: A solution of sulfonate 2b (0.32 g, 1
mmol) in Et2O (1 mL) was added to a mixture of Et3N (0.21
mL, 1.5 mmol), Mg(ClO4)2 (0.67 g, 3 mmol), CH2Cl2 (4 mL)
and Et2O (6 mL) at r.t. When the reaction was complete
(control by TLC), 2% H2SO4 (10 mL) was added to the
reaction mixture and the water layer was extracted with
Et2O, the organic layer was washed with sat. NaHCO3
solution (2 × 10 mL) and dried over Na2SO4. After
evaporation of the solvent, the residue was purified by
column chromatography on silica gel (eluent petroleum
ether), yielding 0.10 g (70%) of diene 3a.
Johnson, W. S. J. Am. Chem. Soc. 1968, 90, 2882.
Synlett 2004, No. 2, 344–346 © Thieme Stuttgart · New York