Synthesis of a biologically active analog of the sex pheromone of cigarette beetle (Lasioderma serricorne)

Article abstract of DOI:10.1007/s11172-005-0390-5

A simple synthesis of a diastereomeric mixture of 7-hydroxy-4,6- dimethylnonan-3-ones was carried out. In the biological action, it is an analog of serricornin, the sex pheromone of the cigarette beetle (Lasioderma serricorne).

Full text of DOI:10.1007/s11172-005-0390-5

1254
Russian Chemical Bulletin, International Edition, Vol. 54, No. 5, pp. 1254—1257, May, 2005
Synthesis of a biologically active analog of
the sex pheromone of cigarette beetle (Lasioderma serricorne)*
ꢀ
A. V. Lozanova, A. V. Stepanov, and V. V. Veselovsky
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: + 7 (095) 135 5328. Eꢀmail: ves@ioc.ac.ru
A simple synthesis of a diastereomeric mixture of 7ꢀhydroxyꢀ4,6ꢀdimethylnonanꢀ3ꢀones
was carried out. In the biological action, it is an analog of serricornin, the sex pheromone of the
cigarette beetle (Lasioderma serricorne).
Key words: 7ꢀhydroxyꢀ4,6ꢀdimethylnonanꢀ3ꢀones, serricornin analog, pheromones, cigaꢀ
rette beetle (Lasioderma serricorne).
The sex pheromone of the female cigarette beetle
Lasioderma serricorne, plant foodstuff pest, is
is due to the intramolecular condensation of ketonitriles 4
in the presence of a base under thermodynamic control
(Thorpe—Ziegler type reaction, for similar examples, see
Ref. 3). The formation of enaminoketone 5 is facilitated
by a longer reaction time and a greater amount of the base
used. Indeed, with an equimolar amount of nitrile 3 and
ButOK, only traces of ketonitrile 4 were detected in the
mixture after the reaction, while compound 5 was the
major reaction product isolated in ∼40 % yield. This was
accompanied by substantial resinification.
a
(4S,6S,7S)ꢀ7ꢀhydroxyꢀ4,6ꢀdimethylnonanꢀ3ꢀone, whose
structure was confirmed by a number of multistep syntheꢀ
ses.1 A mixture of all possible enantioꢀ and diastereomers
of 7ꢀhydroxyꢀ4,6ꢀdimethylnonanꢀ3ꢀone 1a—d is known2
to exhibit a rather high attractant activity.
In view of the simplicity of the preparation of comꢀ
pound 5, it appeared promising to attempt to use it as the
starting compound in the synthesis of target ketoalcohols 1.
It was first planned to carry out hydrolysis of enaminoꢀ
ketone 5 into diketone 6 followed by its transformation
into ketoacid 7 (taking into account the known susceptiꢀ
bility of cyclic diketones to "acid cleavage" under the
action of bases4). Hydrolysis of enaminoketone 5 was
found to require fairly drastic conditions, namely, refluxꢀ
ing of 5 in a EtOH—50% H2SO4 mixture. Unexpectedly,
it was found that the process does not stop after the forꢀ
mation of diketone 6. After complete conversion of the
starting compound 5 (TLC data), a mixture of diastereoꢀ
meric ketoesters 8 was isolated from the reaction mixture
in a high yield. It is noteworthy that this type of cleavage
of cyclic diketones in an acid medium has been described
only for a few examples.** This transformation is accomꢀ
panied by epimerization of a methylꢀbranched asymmetꢀ
ric centers of the molecule (the mixture of ketoesters 8
contains approximately equal amounts of two diastereoꢀ
mers, 1H NMR data).
The key step of the simplest known synthesis of a
mixture of isomers 1 is the condensation of pentanꢀ3ꢀone
(2) with methacrylonitrile (3) in the presence of a cataꢀ
lytic amount of ButOK (Scheme 1);2 however, the genꢀ
eral efficiency of this synthetic route is low due to the
poor yield of the condensation product, a mixture of
diastereomeric ketonitriles 4. Our attempts to optimize
this process have shown that during the reaction perꢀ
formed under the indicated conditions2 and the following
distillation brings about much tar material containing
mainly a highꢀboiling component, which was identified
as (4R*,6S*)ꢀ3ꢀaminoꢀ2,4,6ꢀtrimethylcyclohexꢀ2ꢀenꢀ1ꢀ
one (5). The stereoselective formation of this compound
The possibility of subsequent transformation of ketoꢀ
esters 8 into ketoalkohols of series 1 seemed rather obviꢀ
ous. The mixture of ketoesters 8 was reduced by NaBH4
* Dedicated to Academician N. K. Kochetkov on the occasion
of his 90th birthday.
** For preliminary communication, see Ref. 5.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1218—1221, May, 2005.
1066ꢀ5285/05/5405ꢀ1254 © 2005 Springer Science+Business Media, Inc.

The synthesis of serricornin analog
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 5, May, 2005
1255
Scheme 1
Reagents and conditions: i. ButOK/THF, 0 °C; ii. aq. EtOH—50% H2SO4, refluxing; iii. NaBH4/MeOH, 0 °C; iv. Ac2O/Py/DMAP,
20 °C; v. 3 M aq. KOH/MeOH, ∆; vi. EtMgBr/THF—Et2O, –40 °C.
to give hydroxyesters 9 (characterized also as acetates 10),
which were saponified to give a ∼1 : 1 mixture of diastereoꢀ
meric lactones 11 (two pairs of enantiomers) in a reasonꢀ
able yield. Since one can hardly expect a high degree of
stereocontrol in the above transformations of ketoesters 8,
this stereochemical outcome is apparently due to thermoꢀ
dynamic factors, finally giving rise to an equilibrium mixꢀ
ture of isomers 11 (see related examples6). Then the mixꢀ
ture of previously described lactones 11a 6a and 11b 7 was
condensed with EtMgBr using a known procedure.8
Ketoalcohols 1 obtained in this way, which are known to
exist as equilibrium mixtures of open and semiketal forms,9
were converted into acetates 12 (12a : 12b ≈ 1 : 1,
NMR data), which are used traditionally to identify stereoꢀ
isomers 1.
emental analyses. The previously described components
of mixtures of acetoxyesters 10,6a lactones 11,6a,7 hydroxyꢀ
ketones 1,2 and their acetates 12a 1b,9 and 12b 7 were idenꢀ
tified by comparing their spectroscopic characteristics with
published ones. 13C NMR spectra are most informative
for proving the stereochemistry of acetoxy ketones 12.
Experimental
IR spectra were recorded on a Specord Mꢀ80 instrument.
1H and 13C NMR spectra of solutions in CDCl3 were measured
on a Bruker ACꢀ200 spectrometer relative to the residual proꢀ
tons of the deuterated solvent (δ 7.27 and 77.0). Mass spectra
(EI, 70 eV) were obtained on a Finigan MAT ITDꢀ700 inꢀ
strument.
The Rf values were measured on Silufol plates with fixed
SiO2 layer. Column chromatography was carried out on Silicа
gеl 60 (0.04—0.06 mm, Fluka).
The structures of newly obtained compounds 5, 8,
and 9 were established based on spectroscopic and elꢀ

1256
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 5, May, 2005
Lozanova et al.
The solvents were purified and dried by standard proceꢀ
dures. Commercial pentanꢀ3ꢀone, methacrylonitrile, KOBut,
NaBH4, Ac2O, and DMAP (Aldrich) were used.
Ethyl 5ꢀhydroxyꢀ2,4ꢀdimethylheptanoates (9). To a stirred
solution of a mixture of ketoesters 8 (2.60 g, 13.0 mmol) in
MeOH (30 mL) NaBH4 (0.34 g, 9.0 mmol) was added in porꢀ
tions at 0 °C (Ar) for 30 min. The reaction mixture was stirred
for 1 h at 0 °C, quenched with water (2 mL), neutralized with
5% HCl, and concentrated in vacuo. Water (10 mL) was added
to the residue and the product was extracted with 100 mL of
MeOBut. The organic layer was washed with water (3×10 mL)
and brine (2×15 mL), dried (Na2SO4), and concentrated in vacuo
and the residue was distilled to give 2.50 g (95%) of a mixture of
diastereomeric hydroxyesters 9 as a colorless oil, b.p. 53—56 °C
(2 Torr), Rf 0.26 (hexane—MeOBut, 7 : 3). MS, m/z (Irel (%)):
185 [M – 17]+ (3), 173 (12), 160 (4), 157 (20), 144 (11), 143
(24), 139 (33), 128 (10), 127 (56), 115 (39), 111 (39), 103 (32),
102 (100), 99 (43), 98 (30), 97 (15), 95 (7), 88 (6), 87 (18), 86
(12), 83 (13), 82 (35), 80 (14), 75 (29), 74 (62), 73 (34), 71 (25).
70 (42), 69 (59), 66 (8), 60 (6), 59 (51), 57 (56), 56 (60), 55 (49).
IR (film), ν/cm–1: 688, 768, 856, 976, 1028, 1096, 1184, 1260,
1336, 1380, 1464, 1732, 2876, 2936, 2972, 3430. 1H (δ: 0.78—0.99
(m, 6 H, MeC(2) and MeC(4)); 1.14 (br.t, 3 H, МеC(7), J =
6.7 Hz); 1.23 (br.t, 3 H, МеCH2O, J = 7.0 Hz); 1.30—1.90 (m,
5 H, HC(3), HC(4), HC(6)); 2.50 (m, 1 H, HC(2)); 3.22—3.40
(m, 1 H, HC(5)); 4.09 (br.q, 2 H, H2CO, J = 7.0 Hz).
(4R*,6S*)ꢀ3ꢀAminoꢀ2,4,6ꢀtrimethylcyclohexꢀ2ꢀenꢀ1ꢀone (5).
Nitrile 3 (2.01 g, 30.0 mmol) was added dropwise over a period
of 20 min to a solution of ketone 2 (5.16 g, 60.0 mmol) and
KOBut (3.36 g, 30.0 mmol) in 40 mL of THF stirred at 0 °C
(Ar). The reaction mixture was stirred for 2 h at 0 °C and for 1 h
at 20 °C and treated with MeOBut (50 mL) and water (20 mL).
The organic layer was separated, washed with water (2×10 mL)
and brine (3×10 mL), dried (Na2SO4), and concentrated
in vacuo. The residue (3.9 g) was distilled and the fraction (2.32 g)
with b.p. 140—160 °C (2 Torr) was chromatographed on 100 g
of SiO2. Elution with EtOAc gave 1.75 g (38%) of enaminoketone
5 as colorless crystals with m.p. 99—100 °C (petroleum ether
(here and below, b.p. 40—70 °C)—MeOBut). Found (%):
C, 70.69; H, 10.05; N, 9.11. C9H15NO. Calculated (%): C, 70.55;
H, 9.87; N, 9.14. MS, m/z (Irel (%)): 153 [M]+ (45), 138 (5), 124
(7), 112 (7), 111 (98), 110 (34), 105 (4), 101 (6), 96 (9), 95 (8),
94 (8), 91 (9), 84 (4), 83 (54), 82 (100), 81 (11), 80 (10), 69 (9),
68 (30), 67 (16), 66 (12). IR (CHCl3), ν/cm–1: 664, 720, 792,
1016, 1116, 1180, 1296, 1352, 1396, 1460, 1580, 1608, 2860,
2932, 2968, 3004. 3432, 3536. 1H NMR, δ: 1.09 and 1.20 (both d,
6 H, MeC(4) and MeC(6), J = 7.1 Hz); 1.39 (ddd, 1 H, HC(5),
2J = 12.8 Hz, 2 3J = 12.9 Hz); 1.63 (s, 3 H, МеC(2)); 1.95 (ddd,
1.H, HC(5), 2J = 12.8 Hz, 2 3J = 6.7 Hz); 2.20 and 2.60 (both m,
2 H, HC(4) and HC(6)); 4.63 (br.s, 2 H, H2N).
Ethyl 5ꢀacetoxyꢀ2,4ꢀdimethylheptanoates (10). A solution of
a mixture of hydroxy esters 9 (202 mg, 1.0 mmol) and DMAP
(5 mg, 0.04 mmol) in 1 mL of Ac2O and 1 mL of pyridine was
kept for 20 h at 20 °C (Ar), diluted with 20 mL of MeOBut and
washed successively with 5% HCl (5 mL), a saturated solution
of NaHCO3 (2×5 mL), and brine (2×10 mL), dried (Na2SO4),
and concentrated in vacuo. The residue was chromatographed
on 5 g of SiO2 with a petroleum ether—MeOBut mixture (4 : 1)
as the eluent to give 0.20 g (82%) of a mixture of diastereomers
10 as a colorless oil, Rf 0.58 (hexane—MeOBut, 7 : 3). MS,
m/z (Irel (%)): 244 [M]+ (0.5), 215 (13), 202 (3), 201 (8), 187
(5), 186 (14), 185 (14), 184 (37), 174 (6), 173 (52), 171 (6), 158
(14), 157 (66), 156 (12), 155 (43), 144 (45), 143 (42), 141 (14),
140 (54), 139 (32), 138 (8), 137 (7), 128 (11), 127 (55), 121 (5),
116 (6), 115 (37), 113 (7), 112 (17), 111 (32), 110 (7), 103 (20),
102 (100), 101 (25), 99 (20), 97 (10), 95 (12), 87 (16), 84 (11),
83 (6), 82 (52), 81 (7), 80 (11), 75 (8), 74 (50), 73 (17), 72 (22),
71 (9), 70 (26), 69 (65), 67 (16), 59 (15), 58 (10), 57 (48), 56
Ethyl 2,4ꢀdimethylꢀ5ꢀoxoheptanoates (8). A solution of
enaminoketone 5 (1.69 g, 11.0 mmol) in a mixture of 30 mL of
EtOH and 6 mL of 50% H2SO4 was refluxed for 30 h and
concentrated in vacuo and the residue was treated with 30 mL of
MeOBut and water (10 mL). The organic layer was separated,
washed with water (2×5 mL) and brine (2×10 mL), dried
(Na2SO4), and concentrated in vacuo. The residue (1.85 g) was
chromatographed on 50 g of SiO2. Elution with a petroleum
ether—MeOBut mixture (4 : 1) gave 1.50 g (68%) of a mixture of
diastereomers 8 as a colorless oil with b.p. 50—54 °C (2 Torr),
Rf 0.59 (hexane—MeOBut, 7 : 3). Found (%): C, 65.87;
H, 10.39. C11H20O3. Calculated (%): C, 65.97; H, 10.06. MS,
m/z (Irel (%)): 200 [M]+ (3), 183 (2), 171 (24), 158 (5), 156 (6),
155 (37), 154 (31), 153 (15), 143 (39), 127 (36), 126 (20), 115
(60), 113 (10), 112 (20), 111 (53), 110 (18), 103 (8), 102 (54),
101 (12), 99 (18), 98 (11), 97 (26), 91 (8), 87 (16), 86 (28), 83
(25), 82 (37), 81 (8), 77 (6), 74 (35), 73 (16), 71 (14). 70 (24), 69
(70), 68 (12), 67 (20), 59 (57), 57 (100), 56 (63). IR (film),
ν/cm–1: 856, 976, 1028, 1048, 1104, 1184, 1228, 1256, 1348,
1
(31), 55 (56). H NMR, δ: 0.76—0.91 (m, 6 H, MeC(2) and
MeC(4)); 1.02—1.17 (m, 3 H, H3C(7)); 1.23 (br.t, 3 H,
МеCH2O, J = 7.3 Hz); 1.30—1.85 (m, 5 H, HC(3), HC(4),
HC(6)); 1.99 (s, 3 H, MeCO); 2.46 (m, 1 H, HC(2)); 4.08 (br.q,
2 H, H2CO, J = 7.3 Hz); 4.60—3.80 (m, 1 H, HC(5)).
1
1380, 1416, 1464, 1720, 1736, 2880, 2940, 2976. H NMR, δ:
(3S*,5S*,6S*)ꢀ3,5ꢀDimethylꢀ6ꢀethyltetrahydroꢀ2Hꢀpyranꢀ
2ꢀone (11a) and (3S*,5R*,6S*)ꢀ3,5ꢀdimethylꢀ6ꢀethyltetrahydroꢀ
2Hꢀpyranꢀ2ꢀone (11b). A solution of a mixture of hydroxyesters
9 (2.30 g, 11.5 mmol) in 30 mL of a 3 М solution of KOH in
MeOH was stirred with gentle boiling for 2 h, cooled to 0 °C,
acidified with 15% HCl to pH ∼5, and concentrated in vacuo.
Petroleum ether (100 mL) and water (10 mL) were added to the
residue. The organic layer was separated, washed with water
(2×15 mL) and brine (2×10 mL), dried (Na2SO4), and concenꢀ
trated in vacuo. The residue (1.7 g) was chromatographed on
60 g of SiO2 using a petroleum ether—MeOBut mixture (7 : 3) as
the eluent to give 1.35 g (76%) of a mixture of diastereomeric
lactones 11 as a colorless oil, b.p. 55—58 °C (2 Torr), Rf 0.30
(hexane—MeOBut, 7 : 3). MS, m/z (Irel (%)): 156 [M]+ (2), 149
(3), 144 (3), 140 (4), 128 (5), 127 (46), 114 (10), 102 (14), 99
0.97—1.08 (m, 6 H, MeC(2), MeC(4)); 1.11 (br.t, 3 H, MeC(6),
J = 6.7 Hz); 1.23 (br.t, 3 H, МеCH2O, J = 7.0 Hz); 1.30 (ddd,
ꢀ
0.5 H, HC(3), J = 13.8 Hz, J = 7.6 Hz, J = 5.9 Hz); 1.57 (ddd,
ꢀ
0.5 H, HC(3), J = 14.1 Hz, J = 9.0 Hz, J = 4.8 Hz); 1.77 (ddd,
ꢀ
0.5 H, HC(3), J = 14.1 Hz, J = 8.9 Hz, J = 5.3 Hz); 2.03 (ddd,
ꢀ
0.5 H, HC(3), J = 13.9 Hz, J = 8.9 Hz, J = 6.0 Hz); 2.25 (m,
4 H, HC(2), HC(4), H2C(6)); 4.09 (br.q, 2 H, H2CO, J =
7.0 Hz). 13C NMR, δ: 7.6 (C(7)); 14.8 (MeCH2O); 16.7, 17.3
and 17.5 (MeC(2), MeC(4)); 34.4 and 35.2 (C(3)); 36.8 and
37.1 (C(6)); 38.0 and 38.5 (C(2)); 44.9 (C(4)); 60.5 (CH2O);
175.8 and 176.0 (C(1)); 214.6 and 215.0 (C(5)).
ꢀ
Nonꢀoverlapping signals of protons of the stereoisomers.

The synthesis of serricornin analog
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 5, May, 2005
1257
(30), 98 (50), 95 (3), 88 (3), 83 (7), 82 (19), 80 (7), 78 (6), 71
(17), 70 (74), 69 (58), 67 (10), 59 (9), 58 (17), 57 (67), 56 (100),
55 (72). IR (film), ν/cm–1: 744, 812, 936, 988, 1040, 1108, 1172,
1212, 1324, 1380, 1464, 1732, 2880, 2936, 2968. 1H (δ: 0.92—1.04
(m, 6 H, MeC(5) and MeCH2); 1.22, 1.26 (both d, 1.5 H each,
H2C(5), HC(6), H2C(8)); 2.01 (s, 3 H, MeCO); 2.28—2.66 (m,
3 H, H2C(2), HC(4)); 4.57—4.74 (m, 1 H, HC(7)). The
13C NMR spectrum of isomer 12a (cf. Ref. 1b), δ: 7.75 (C(1));
10.08 (C(9)); 14.32 (CH3—C(6)); 16.53 (CH3—C(4)); 21.03
(CH3CO); 24.05 (C(5)); 33.52 (C(6)); 34.22 (C(2)); 35.76
(C(8)); 43.37 (C(4)); 78.76 (C(7)); 170.96 (MeCO); 215.05
(C(3)). The 13C NMR spectrum of isomer 12b (cf. Ref. 7),
δ: 7.69 (C(1)); 9.92 (C(9)); 15.72 (CH3—C(6)); 18.08
(CH3—C(4)); 21.03 (CH3CO); 24.05 (C(5)); 33.91 (C(6)); 34.22
(C(2)); 35.31 (C(8)); 43.73 (C(4)); 77.97 (C(7)); 170.96
(MeCO); 214.97 (C(3)).
ꢀ
МеC(3), J = 6.9 Hz) ; 1.39—2.08 (m, 4 H, HC(4), H2CMе);
2.49 (m, 1 H, HC(3)); 3.84 (ddd, 0.5 H, HC(6), 11b, J = 9.9 Hz,
ꢀ
J = 7.0 Hz, J = 2.8 Hz); 4.17 (ddd, 0.5 H, HC(6), 11a, J =
8.6 Hz, J = 6.1 Hz, J = 3.0 Hz). 13C NMR, δ, 11a: 9.88, 11.28,
ꢀ
17.90, 26.21, 29.39, 31.34, 35.97, 85.37, 174.51 (cf. Ref. 1b);
11b: 8.63, 17,26, 25.56, 32.72, 36.25, 37.66, 87.94, 174.57.
7ꢀHydroxyꢀ4,6ꢀdimethylnonanꢀ3ꢀones (1). A 1.36 M soluꢀ
tion of EtMgBr (7 mL, 9.52 mmol) in Et2O was added over a
period of 5 min to a solution of a mixture of lactones 11 (1.25 g,
8.0 mmol) in 20 mL of THF stirred at –40 °C (Ar). The reaction
mixture was stirred for 2 h at –40 °C and for 2 h at 20 °C and
quenched with a saturated solution of NH4Cl (5 mL). The aqueꢀ
ous layer was separated and extracted with 50 mL of MeOBut.
The combined organic layer was washed with water (2×10 mL)
and brine (2×10 mL), dried (Na2SO4), and concentrated
in vacuo. The residue (1.55 g) was chromatographed on 60 g of
SiO2, using a petroleum ether—MeOBut mixture (2 : 1) as the
eluent to give 1.28 g (86%) of a mixture of diastereomers 1 as a
colorless oil, Rf 0.56—0.21 (hexane—MeOBut, 2 : 1) (cf. Ref. 9).
MS, m/z (Irel (%)): 168 [M – H2O]+ (100), 139 (12), 125 (14),
111 (9), 99 (72), 95 (15), 83 (30), 71 (42), 69 (39), 67 (25), 57
(54), 55 (67), 53 (12) (cf. Ref. 2).
This work was financially supported by the Council on
Grans of the President of the Russian Federation (Proꢀ
gram for the State Support of Leading Scientific Schools
of the Russian Federation, Grant NShꢀ1802.2003.3).
References
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A solution of a mixture of hydroxyketones 1 (0.45 g, 2.42 mmol)
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pyridine was kept for 20 h at 20 °C (Ar), diluted with 20 mL
of MeOBut, washed successively with 5% HCl (10 mL),
a saturared solution of NaHCO3 (2×10 mL), and brine
(2×10 mL), dried (Na2SO4), and concentrated in vacuo. The
residue was chromatographed on 10 g of SiO2 using a 5 : 1
petroleum ether—MeOBut mixture as the eluent to give 0.43 g
(78%) of a mixture of diastereomers 12 as a colorless oil, b.p.
66—68 °C (2 Torr). MS, m/z (Irel (%)): 168 [M – AcOH]+ (24),
157 (12), 140 (2), 139 (10), 128 (4), 127 (4), 125 (3), 117 (3),
112 (5), 111 (18), 101 (2), 99 (9), 97 (3), 91 (2), 87(6), 86 (23),
84 (5), 83 (13), 82 (6), 70 (21), 69 (23), 57 (100), 56 (9), 55 (26).
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0.96—1.08 (m, 6 H, H3C(1), MeC(4)); 1.16—1.81 (m, 5 H,
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Received January 12, 2005;
ꢀ
Nonꢀoverlapping signals of protons of the stereoisomers.
in revised form March 28, 2005