Stereocontrolled synthesis of (3Z,5E)-6-aryl-3-methylhexa-3,5-dien-1-ols, intermediates in the synthesis of strobilurin antibiotics

Article abstract of DOI:10.1007/s11172-010-0172-6

(2E,4E)-5-Aryl-2-(2-benzyloxyethyl)penta-2,4-dien-1-als (aryl is phenyl and 4-methox-yphenyl) were reduced with NaBH₄ quantitatively and stereospecifically to the corresponding penta-2(E),4(E)-dien-1-ols. The hydroxymethyl group in the latter was transformed into a methyl one with a stereoselectivity of 92-97%. Debenzylation of the resulting (1E,3Z)-1-aryl-6- benzyloxy-4-methylhexa-1,3-dienes with AlCl₃ in the presence of PhNMe₂ afforded the target (3Z,5E)-6-aryl-3-methylhexa-3,5-dien-1- ols; the configuration of the C=C bonds in the conjugated aryl diene systems was retained at 95%.

Full text of DOI:10.1007/s11172-010-0172-6

Russian Chemical Bulletin, International Edition, Vol. 59, No. 4, pp. 848—851, April, 2010
848
Stereocontrolled synthesis of (3Z,5E)ꢀ6ꢀarylꢀ3ꢀmethylhexaꢀ3,5ꢀdienꢀ1ꢀols,
intermediates in the synthesis of strobilurin antibiotics
N. Ya. Grigorieva, V. A. Popovsky, A. V. Stepanov, and N. G. Kolotyrkina
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Eꢀmail: ves@ioc.ac.ru
(2E,4E)ꢀ5ꢀArylꢀ2ꢀ(2ꢀbenzyloxyethyl)pentaꢀ2,4ꢀdienꢀ1ꢀals (aryl is phenyl and 4ꢀmethoxꢀ
yphenyl) were reduced with NaBH4 quantitatively and stereospecifically to the corresponding
pentaꢀ2(E),4(E)ꢀdienꢀ1ꢀols. The hydroxymethyl group in the latter was transformed into
a methyl one with a stereoselectivity of 92—97%. Debenzylation of the resulting (1E,3Z)ꢀ1ꢀarylꢀ
6ꢀbenzyloxyꢀ4ꢀmethylhexaꢀ1,3ꢀdienes with AlCl3 in the presence of PhNMe2 afforded the target
(3Z,5E)ꢀ6ꢀarylꢀ3ꢀmethylhexaꢀ3,5ꢀdienꢀ1ꢀols; the configuration of the C=C bonds in the conꢀ
jugated aryl diene systems was retained at 95%.
Key words: stereocontrolled synthesis, strobilurins, dienols, debenzylation, dehydroxylation.
Recently,1 we have demonstrated that condensation of
cinnamaldehyde and 4ꢀmethoxycinnamaldehyde with
deprotonated Nꢀ(tertꢀbutyl)ꢀ4ꢀbenzyloxybutanimine steꢀ
reoselectively (≥98%) gives (2E,4E)ꢀdienals 1a and 1b,
respectively, in high yields (Scheme 1). With the aim of
using these compounds2 for the design of the (1E,3Z)ꢀ1ꢀ
arylꢀ4ꢀmethylalkadiene system of strobilurin antibiotics
of the general formula 2,3,4 we studied a transformation of
the formyl group of aldehydes 1a,b into a methyl one
through the formation of intermediate dienols 3a,b and
Scheme 1
R = H (a), OMe (b)
Reagents and conditions: i. NaBH4/EtOH, 3 h, 20 °C; ii. Py•SO3/THF, 2.5 h, 0 °C; iii. LiAlH4, 24 h, 20 °C; iv. BuLi/C6H14, 0 °C;
v. TsCl/HMPA—Et2O (1 : 3), 0 °C, 2.5 h.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 830—833, April, 2010.
1066ꢀ5285/10/5904ꢀ0848 © 2010 Springer Science+Business Media, Inc.

(3Z,5E)ꢀ6ꢀArylꢀ3ꢀmethylhexaꢀ3,5ꢀdienꢀ1ꢀols
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
849
benzyloxyalkadienes 4a,b followed by debenzylation of
the latter (see Scheme 1). The present communication
is concerned with detailed analysis of the above transforꢀ
mations.
and the C=C bond (δ 3.46)6 and a signal for the CH2
group between two C=C bonds (δ 2.98).6 Their integral
intensity ratio is also ~2 : 1. A similar pattern was
observed in the 1H NMR spectra of the final mixture upon
the reduction of dienol 3b. Apart from the signals for diene
4b, the spectra contain two doublets for the =CH2 group
at δ 5.0 and 4.90 with an integral intensity ratio of ~3 : 1
and doublets for the groups ArCH2C=C (δ 3.40)
and C=CCH2C=C (δ 2.96) with an integral intensity ratio
of ~3 : 1.
Variation of the conditions of the synthesis of sulfates
from dienols 3a,b and their reduction (reaction tempeꢀ
rature, reaction time, and replacement of LiAlH4 by
LiAl(OEt)H3 or [AlH3]) did not make the reaction more
selective. The content of side dienes in compound 4a was
lowered to ~5—7% by reversing the order of mixing of the
reagents (see Experimental).
The high content of impurities in diene 4b and considꢀ
erable losses of the target dienes during their purification
by column chromatography prompted us to search for an
alternative way of converting dienols 3a,b into compounds
4a,b. For this purpose, we obtained tosylates from dienols
3a,b and studied their reduction with LiAlH4 (method B).
In the case of dienol 3b, the target diene 4b contained no
impurities 5b or 6b. However, the product was contamiꢀ
nated with (E)ꢀisomer 7b (1H NMR): the spectrum showed
additional minor signals for the groups H2C(2) (t, δ 2.45)
and HC(4) (d, δ 6.08). By comparing the integral intensiꢀ
ties of these signals with the corresponding signals for
diene 4b, we estimated the ratio of 4b : 7b at ~95 : 5. Anaꢀ
lytically pure diene 4b was isolated by flash chromatograꢀ
phy. The content of (E)ꢀisomer 7a in the transformation
3a→4a according to method B was ~20% (1H NMR).
Thus, method A is preferred for the reduction of dienol
3a and method B, for the reduction of dienol 3b.
Debenzylation of benzyloxyalkadienes 4a,b was a priori
a difficult problem. Out of a number of methods recomꢀ
mended for deprotection of various benzyl ethers,7—12 only
one9 provided a satisfactory result: treatment of diene 4a
with AlCl3 in the presence of PhNMe2 afforded a mixture
of the target dienol 8a and its (E)ꢀisomer 9a in a ratio of
9 : 1 (Scheme 2). Similar treatment of diene 4b gave
a mixture of dienols 8b and 9b in a ratio of 9.5 : 0.5
(1H NMR). Note that the deprotection of benzyl ethers
containing a conjugated aryl diene system of C=C bonds
Reduction of dienals 1a,b with NaBH4 according to
a standard procedure gives dienols 3a,b in quantitative
yields. Their structures were confirmed by elemental
analysis and physicochemical methods (primarily,
1H NMR spectroscopy). For instance, C—H correlation
methods and COSY revealed the following parameters of
the H atoms of the diene system in dienol 3a, δ: 6.33
(d, J = 11.0 Hz); 6.61 (d, J = 15.5 Hz); 7.01 (dd, J1 = 11.0 Hz,
J2 = 15.5 Hz). Out of the pair of the aforementioned douꢀ
blets, only the former at δ 6.33 shows NOE (2.2%) with
H2C(1). Therefore, this signal can be assigned to HC(3)
and, second, the (E)ꢀconfiguration of the C(2)=C(3) bond
can be concluded. This conclusion was confirmed by NOE
(3.1%) between the H2C(1´) and H2C(4) atoms. The latꢀ
ter doublet in the 1H NMR spectrum of dienol 3a (δ 6.61)
was assigned to HC(5). Its coupling constant with HC(4)
(J = 15.5 Hz) suggests the (E)ꢀconfiguration of the
C(4)=C(5) bond. The (E,E)ꢀconfiguration of dienol 3b
was proved in a similar way.
Treatment of dienols 3a,b with the complex Py•SO3
followed by in situ reduction of the resulting sulfates with
LiAlH4 (method A)5 gives dienes 4a,b as major reacꢀ
tion products. Their structures were confirmed by NMR
spectroscopy using C—H correlation, COSY, and NOE
experiments as described above for compounds 3a,b.
However, dienes 4a,b are not the sole reaction prodꢀ
ucts. According to 1H NMR data, the final mixtures conꢀ
tain two byꢀproducts. Their total content does not exceed
10% in the reduction of dienol 3a and is ~25% in the case
of compound 3b. Since the highꢀresolution mass spectra
of the reduction products show only the ions [M]+,
[M + Na]+, and [M + K]+, we assume that the byꢀprodꢀ
ucts are isomeric with compounds 4a and 4b regarding the
1
position of the C=C bonds. Based on H NMR data, we
assigned structures 5a,b to the major dienes of the mixꢀ
tures and structures 6a,b to the minor dienes of the mixꢀ
tures. Indeed, the 1H NMR spectra of the final mixture in
the reduction of dienol 3a show two minor doublets for the
terminal methylidene group at δ 5.04 and 4.93 with an
integral intensity ratio of ~2 : 1. In addition, the spectra
exhibit a doublet for the CH2 group between the Ph ring
Scheme 2
R = H (a), OMe (b)

850
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
Grigorieva et al.
yield ~100%, m.p. 59—61 °C (from hexane—ether, 1 : 1).
Found (%): C, 77.70; H, 7.57. C21H24O3. Calculated (%):
C, 77.75; H, 7.46. UV, λmax/nm (ε): 215 (12 000), 303 (31 500).
IR, ν/cm–1: 3425, 3032, 3012, 2840, 1610, 1512, 1456, 1360,
1304, 1252, 1176, 1096, 1036, 964, 892, 852, 820, 700. 1H NMR,
δ: 2.68 (t, 2 H, H2C(1´), J = 6.2 Hz); 2.82 (br.s, 1 H, OH); 3.66
(t, 2 H, H2C(2´), J = 6.2 Hz); 3.83 (s, 3 H, MeO); 4.15 (s, 2 H,
H2C(1)); 4.56 (s, 2 H, H2CPh); 6.29 (d, 1 H, HC(3), J = 10.9 Hz);
6.54 (d, 1 H, HC(5), J = 15.4 Hz); 6.85 (dd, 1 H, HC(4),
J1 = 10.9 Hz, J2 = 15.4 Hz); 6.88 (d, 2 H, Ar, J = 8.8 Hz); 7.25—7.46
(m, 7 H, Ar). 13C NMR, δ: 29.88 (C(1´)); 55.27 (MeO); 68.10
(C(1)); 69.71 (C(2´)); 73.21 (CH2Ph); 122.06 (C(4)); 128.17
(C(3)); 132.93 (C(5)); 138.24 (C(2)). MS, m/z (Irel (%)): 324
[M]+ (5), 187 (10), 185 (22), 160 (17.5), 147 (15), 134 (33.5),
121 (68.5), 115 (14), 92 (14), 91 (100), 77 (19), 65 (28), 55 (16),
51 (11), 43 (32.5), 42 (15), 39 (13).
(1E,3Z)ꢀ6ꢀBenzyloxyꢀ4ꢀmethylꢀ1ꢀphenylhexaꢀ1,3ꢀdiene (4a).
Method A. A suspension of Py•SO3 (1.10 g, 7 mmol) in THF
(50 mL) was vigorously stirred at –15 °C while a solution of
dienol 3a (1.30 g, 4.42 mmol) in THF (20 mL) was added for
20 min. The reaction mixture was warmed to 0 °C, stirred at this
temperature for 2.5 h, and cooled to –10 °C. A solution of LiAlH4
(26.4 mmol) in THF (22 mL) was added dropwise. Then the
mixture was slowly warmed to ~20 °C, stirred at this temperature
for 24 h, and recooled to –10 °C. Water (1 mL), 15% NaOH
(1 mL), and again water (3 mL) were successively added dropwise.
The precipitate that formed was filtered off and thoroughly
washed with tertꢀbutyl methyl ether (TBME). After routine workꢀ
up of the combined organic phases, the residue (1.15 g) was
chromatographed on SiO2 (50 g). Gradient elution from hexane
to 10% TBME gave diene 4a (0.58 g, 50%) contaminated with
dienes 5a and 6a (total content 6%) in a ratio of ~2 : 1 (1H NMR).
Analytically pure diene 4a was isolated by HPLC, Rf 0.48 (10%
TBME in hexane). UV, λmax/nm (ε): 211 (18 120), 296 (26 170).
IR, ν/cm–1: 3060, 3028, 2960, 2856, 1644, 1596, 1496, 1456,
1364, 1176, 1100, 1028, 960, 748, 696. 1H NMR, δ: 1.90 (s, 3 H,
MeC(4)); 2.65 (t, 2 H, H2C(5), J = 6.2 Hz); 3.62 (t, 2 H, H2C(6),
J = 6.27 Hz); 4.55 (s, 2 H, H2CPh); 6.11 (d, 1 H, HC(3),
J = 11.0 Hz); 6.48 (d, 1 H, HC(1), J = 15.5 Hz); 7.05 (dd, 1 H,
HC(2), J1 = 11.0 Hz, J2 = 15.5 Hz); 7.20—7.50 (m, 10 H, Ph).
13C NMR, δ: 24.46 (Me); 33.21 (C(5)); 68.91 (C(6)); 72.96
(CH2Ph); 125.29 (C(2)); 126.19 (C(3)); 127.01 (C(1)); 136.71
(C(4)). MS, m/z (Irel (%)): 278 [M]+ (14), 187 (13), 169 (10),
157 (47.5), 144 (10), 143 (10), 142 (15), 141 (14), 130 (31.5),
129 (26.5), 115 (19.5), 91 (100), 81 (14), 79 (13), 77 (12.5), 65 (10),
51 (16), 43 (10). Highꢀresolution MS. Found: [M + K]+,
317.1313. C20H22O. Calculated: [M + K]+, 317.1302.
is not described in the references cited above. The target
dienols 8a,b were isolated by flash chromatography and
characterized using physicochemical methods, including
highꢀresolution mass spectrometry and 1H NMR specꢀ
troscopy (C—H correlation, COSY, and NOE, as deꢀ
scribed for compound 3a).
Experimental
UV spectra were recorded on a Specord UV—Vis instrument
in ethanol. IR spectra were recorded on a Perkin—Elmer 577
spectrometer in thin films or in solutions in CHCl3 (for alcoꢀ
hols). 1H and 13C NMR spectra were recorded on a Bruker ACꢀ200
spectrometer in CDCl3 with reference to the signals of the solꢀ
vent (δ 7.27 and 77.0, respectively). The signals for the olefinic
protons in the 1H NMR spectra were assigned from the NOE
experiment. In the 13C NMR spectra of the compounds deꢀ
scribed, the signals for the C atoms of the benzene rings are
omitted. Mass spectra (EI, 70 eV) were measured on a Kratos
MSꢀ30 instrument; peaks with Irel >10% are cited only (except
for molecular ion peaks). Highꢀresolution mass spectra were
measured on a micrOTOF II instrument (Bruker Daltonics)
(ESI, m/z scan range 50—3000, positive ions (capillary voltage
4500 V)). Samples were syringed as solutions in acetonitrile,
flow rate 3 μL min–1, interface temperature 180 °C, nitrogen as
a spraying gas (4.0 L min–1). Melting points were determined on
a Kofler microscope stage. Column chromatography was perꢀ
formed on Silica gel 60 (0.04—0.06 mm, Fluka). Main solvents
were purified as follows: diethyl ether and THF were kept over
KOH, distilled successively over metallic Na and LiAlH4, reꢀ
fluxed with sodium benzophenone ketyl until the solvent turned
stable blue, and distilled immediately to a reaction vessel; hexꢀ
ane was distilled over metallic Na. A solution of BuLi in hexane
was prepared according to a standard procedure. Experiments
involving unstable reagents were carried out under argon in glassꢀ
ware kept at 160 °C for 12 h and cooled in an argon flow.
"Routine workup" of organic extracts consisted of washing to
pH ~7, drying with Na2SO4, and concentration in vacuo on
a rotary evaporator.
(2E,4E)ꢀ2ꢀ(2ꢀBenzyloxyethyl)ꢀ5ꢀphenylpentaꢀ2,4ꢀdienꢀ1ꢀol
(3a) was obtained by reduction of compound 1a (see Ref. 1) with
NaBH4 according to a standard procedure. Yield ~100%, b.p.
185 °C (6•10–2 Torr (bath)). Found (%): C, 81.55; H, 7.62.
C20H22O2. Calculated (%): C, 81.60; H, 7.53. UV, λmax/nm (ε):
211 (22 570), 297 (25 070). IR, ν/cm–1: 3400, 3060, 3028, 2924,
2860, 2244, 1716, 1592, 1492, 1452, 1360, 1204, 1180, 1004,
960, 904, 696, 648. 1H NMR, δ: 2.70 (t, 2 H, H2C(1´), J = 6.2 Hz);
3.67 (t, 2 H, H2C(2´), J = 6.2 Hz); 4.17 (s, 2 H, H2C(1)); 4.57
(s, 2 H, H2CPh); 6.33 (d, 1 H, HC(3), J = 11.0 Hz); 6.61 (d, 1 H,
HC(5), J = 15.5 Hz); 7.01 (dd, 1 H, HC(4), J1 = 11.0 Hz,
J2 = 15.5 Hz); 7.22—7.45 (m, 10 H, Ph). 13C NMR, δ: 29.82
(C(1´)); 67.93 (C(1)); 69.56 C(2´); 73.19 (CH2Ph); 124.00 (C(4));
126.34 (C(3)); 133.27 (C(5)); 139.29 (C(2)). MS, m/z (Irel (%)):
294 [M]+ (1.5), 186 (10), 157 (10), 155 (24.5), 143 (13), 141 (11),
130 (10.5), 129 (21), 128 (26), 117 (10), 115 (32), 107 (17.5),
105 (11.5), 104 (12.5), 101 (15), 95 (13), 92 (57), 91 (100),
88 (17), 80 (31), 78 (54.5), 77 (30), 76 (40), 69 (24), 67 (43),
65 (78), 63 (14).
Method B. Sequential treatment of compound 3a with BuLi,
TsCl, and LiAlH4 as described below for compound 3b gave
a ~4 : 1 mixture of dienes 4a and 7a (1H NMR).
(1E,3Z)ꢀ6ꢀBenzyloxyꢀ1ꢀ(4ꢀmethoxyphenyl)ꢀ4ꢀmethylhexaꢀ
1,3ꢀdiene (4b). Method A. Treatment of alcohol 3b with Py•SO3
followed by in situ reduction of the resulting sulfate with LiAlH4
as described above for compound 3a gave a mixture of dienes 4b,
5b, and 6b in a ratio of 4 : 1.2 : 0.4 (1H NMR). The mixture was
not separated by flash chromatography.
Method B. A solution of dienol 3b (0.87 g, 2.7 mmol) in
a mixture of Et2O (17.5 mL) and HMPA (2.6 mL) was vigorousꢀ
ly stirred at 0 °C while a solution of BuLi (3.23 mmol) in hexane
(1.9 mL) and a solution of TsCl (0.62 g, 3.24 mmol) in HMPA
(2.6 mL) were successively added. The reaction mixture was
(2E,4E)ꢀ2ꢀ(2ꢀBenzyloxyethyl)ꢀ5ꢀ(4ꢀmethoxyphenyl)pentaꢀ
2,4ꢀdienꢀ1ꢀol (3b) was obtained as described for compound 3a,

(3Z,5E)ꢀ6ꢀArylꢀ3ꢀmethylhexaꢀ3,5ꢀdienꢀ1ꢀols
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
851
stirred at 0 °C for 2.5 h and cooled to –15 °C. A solution of
LiAlH4 (18.7 mmol) in THF (11 mL) was added dropwise and
the mixture was slowly warmed to ~20 °C, stirred at this temperꢀ
ature for 20 h, and subjected to the same workup as for comꢀ
pound 4a (method A) to give an oily mixture (0.9 g) containing
dienes 4b and 7b in a ratio of ~95 : 5 (1H NMR). Flash chromaꢀ
tography of this mixture on SiO2 with gradient elution from
hexane to 50% benzene gave analytically pure benzyloxyhexaꢀ
diene 4b (0.5 g, 50%), b.p. 165 °C (0.1 Torr (bath)). Found (%):
C, 81.65; H, 7.60. C21H24O2. Calculated (%): C, 81.78; H, 7.84.
UV, λmax/nm (ε): 215 (8600), 303 (22 200). IR, ν/cm–1: 3032,
2984, 2856, 1604, 1512, 1460, 1360, 1300, 1248, 1180, 1100,
1032, 960, 880, 864, 850, 812, 736, 696. 1H NMR, δ: 1.89 (s, 3 H,
MeC(4)); 2.63 (t, 2 H, H2C(5), J = 7.2 Hz); 3.61 (t, 2 H, H2C(6),
J = 7.2 Hz); 3.83 (s, 3 H, MeO); 4.57 (s, 2 H, CH2Ph); 6.08
(d, 1 H, HC(3), J = 10.9 Hz); 6.42 (d, 1 H, HC(1), J = 15.5 Hz);
6.87 (d, 2 H, Ar, J = 8.8 Hz); 6.90 (dd, 1 H, HC(2), J1 = 10.9 Hz,
J2 = 15.5 Hz); 7.20—7.50 (m, 7 H, Ph). 13C NMR, δ: 24.46
(MeC(3)); 33.11 (C(5)); 55.29 (MeO); 68.88 (C(6)); 72.94
(CH2Ph); 123.30 (C(2)); 128.36 (C(3)); 130.00 (C(1)); 138.42
(C(4)). MS, m/z (Irel (%)): 308 [M]+ (51), 188 (21), 187 (96),
174 (13), 173 (22), 172 (13), 160 (60), 159 (44), 158 (31),
157 (24), 145 (17), 144 (21), 141 (24), 135 (10), 134 (32), 131 (32),
129 (39), 128 (28), 122 (10), 121 (45), 115 (14), 92 (19), 91(100),
79 (29), 77 (49), 69 (18), 65 (15), 55 (20), 44 (11), 42 (17).
(3Z,5E)ꢀ3ꢀMethylꢀ6ꢀphenylhexaꢀ3,5ꢀdienꢀ1ꢀol (8a). A soluꢀ
tion of benzyl ether 4a (0.41 g, 1.51 mmol) in CH2Cl2 (1.5 mL)
was vigorously stirred at 20 °C while PhNMe2 (0.8 mL, 6.04 mmol)
and anhydrous AlCl3 (0.61 g, 4.53 mmol) were successively
added. The reaction mixture was stirred for 1 h and then cooled
to 0 °C. Dilute HCl (1 : 10, 12 mL) was added dropwise and the
resulting layers were separated after 10 min. The product from
the aqueous layer was extracted with CH2Cl2 (3×7 mL). After
routine workup of the combined extracts, the residue (0.42 g)
contained a mixture of dienol 8a and its (E,E)ꢀisomer 9a in
a ratio of ~9 : 1 (1H NMR). Flash chromatography of this mixꢀ
ture on SiO2 (25 g) with gradient elution from hexane to 40%
TBME gave dienol 8a (0.12 g). UV, λmax/nm (ε): 235 (15 040),
301 (33 840). IR, ν/cm–1: 3620, 3445, 3036, 3008, 2960, 2928,
2884, 1700, 1640, 1596, 1496, 1448, 1380, 1364, 1232, 1196,
1044, 964, 884, 808, 620. 1H NMR, δ: 1.56 (br.s, 1 H, OH); 1.93
(s, 3 H, MeC(3)); 2.59 (t, 2 H, H2C(2), J = 6.6 Hz); 3.78 (t, 2 H,
H2C(1), J = 6.6 Hz); 6.20 (d, 1 H, HC(4), J = 10.9 Hz); 6.50
(d, 1 H, HC(6), J = 15.4 Hz); 7.05 (dd, 1 H, HC(5), J1 = 10.9 Hz,
J2 = 15.4 Hz); 7.08—7.42 (m, 5 H, Ph). 13C NMR, δ: 24.12
(MeC(3)); 35.87 (C(2)); 60.90 (C(1)); 124.93 (C(5)); 126.27
(C(4)); 131.09 (C(6)); 137.78 (C(3)). Highꢀresolution MS.
Found: [M + H]+, 189.1255; [M + Na]+, 211.1083; C13H16ONa.
Calculated: [M + H]+, 189.1274; [M + Na]+, 211.1093.
70%, m.p. 55—57 °C (from hexane—ether, 1 : 1). Found (%):
C, 77.02; H, 8.10. C14H18O2. Calculated (%): C, 77.03; H, 8.31.
UV, λmax/nm (ε): 224 (10 900), 303 (35 000). IR, ν/cm–1: 3640,
3450, 3008, 2960, 2840, 1604, 1512, 1460, 1448, 1384, 1304,
1248, 1176, 1040, 960, 840, 816, 664. 1H NMR, δ: 1.67 (t, 1 H,
OH, J = 5.8 Hz); 1.88 (s, 3 H, MeC(3)); 2.56 (t, 2 H, H2C(2),
J = 6.4 Hz); 3.76 (dt, 2 H, H2C(1), J1 = 5.8 Hz, J2 = 6.4 Hz);
3.81 (s, 3 H, MeO); 6.19 (d, 1 H, HC(4), J = 10.9 Hz); 6.44
(d, 1 H, HC(6), J = 15.5 Hz); 6.86 (d, 2 H, Ar, J = 8.7 Hz); 6.91
(dd, 1 H, HC(5), J1 = 10.9 Hz, J2 = 15.5 Hz); 7.35 (d, 2 H, Ar,
J = 8.7 Hz). 13C NMR, δ: 24.04 (MeC(3)); 35.82 (C(2));
55.29 (MeO); 60.89 (C(1)); 122.97 (C(5)); 128.79 (C(4));
130.64 (C(6)), 134.53 (C(3)). MS, m/z (Irel (%)): 219 [M + 1]+
(20), 218 [M]+ (100), 188 (16), 187 (70), 173 (14), 172 (34),
159 (22), 158 (21), 144 (18), 134 (12), 121 (29), 115 (29), 101 (10),
91(13), 78 (15), 76 (11), 59 (41), 56 (11), 45 (10), 43 (26),
42 (19), 41 (11).
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 07ꢀ03ꢀ00454).
References
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(3Z,5E)ꢀ6ꢀ(4ꢀMethoxyphenyl)ꢀ3ꢀmethylhexaꢀ3,5ꢀdienꢀ1ꢀol
(8b) was obtained as described above for compound 8a. Yield
Received January 22, 2010