Enantioselective synthesis of alkyl-branched alkanes. Synthesis of the stereoisomers of 7,11-dimethylheptadecane and 7-methylheptadecane, components of the pheromone of Lambdina species

Article abstract of DOI:10.1021/jo0055436

The stereoisomers of 7,11-dimethylheptadecane and 7-methylheptadecane have been synthesized. The key step used has been the intramolecular hydride transfer from a secondary γ-benzyloxy group with defined absolute stereochemistry to a cation generated by Lewis acid treatment of the suitable tertiary Co₂(CO)₆-complexed propargylic alcohol. The application of this method provided stereochemically defined α-alkyl-γ-hydroxy-acetylenes that after hydrogenation and further reductive elimination of the hydroxyl group yielded sec-alkyl hydrocarbons.

Full text of DOI:10.1021/jo0055436

7896
J . Org. Chem. 2000, 65, 7896-7901
En a n tioselective Syn th esis of Alk yl-Br a n ch ed Alk a n es. Syn th esis
of th e Ster eoisom er s of 7,11-Dim eth ylh ep ta d eca n e a n d
7-Meth ylh ep ta d eca n e, Com p on en ts of th e P h er om on e of La m bd in a
Sp ecies
David D. D´ıaz and V´ıctor S. Mart´ın*
Instituto Universitario de Bio-Orga´nica “Antonio Gonza´lez”, Universidad de La Laguna,
C/ Astrofı´sico Francisco Sa´nchez, 2, 38206 La Laguna, Tenerife, Spain
vmartin@ull.es
Received J une 14, 2000
The stereoisomers of 7,11-dimethylheptadecane and 7-methylheptadecane have been synthesized.
The key step used has been the intramolecular hydride transfer from a secondary γ-benzyloxy
group with defined absolute stereochemistry to a cation generated by Lewis acid treatment of the
suitable tertiary Co2(CO)6-complexed propargylic alcohol. The application of this method provided
stereochemically defined R-alkyl-γ-hydroxy-acetylenes that after hydrogenation and further reduc-
tive elimination of the hydroxyl group yielded sec-alkyl hydrocarbons.
Sch em e 1
In tr od u ction
Compounds having stereochemically defined alkyl-
branched hydrocarbon chains are widespread in nature.1
This fact is particularly important when enantiomerically
active pheromones are considered.2 (S)-7-Methylhepta-
decane (1) and/or meso-7,11-dimethylheptadecane (2)
have been established as the bioactive female pheromone
components in Lambdina athasaria (spring hemlock
looper moth),3 Lambdina pellucidaria (pitch pine looper
moth),4 Lambdina fiscellaria fiscellaria (Hulst),5 and
Lambdina fiscellaria lugubrosa (Hulst).6 Racemic (()-1
and a mixture of meso-2 and (()-3 have been synthesized
and found to be bioactive.4 The stereocontrolled syntheses
of (R)-1, (S)-1, meso-2, (S,S)-3, and (R,R)-3 have very
recently been reported and showed that the pheromone
components are (S)-1 and meso-2.7
Sch em e 2
main synthetic advantage of our method is that we can
obtain sec-dialkyl acetylenes with absolute stereochem-
ical control. In this paper, we report on our studies
directed to the enantiomeric synthesis of methyl- and
3-methylene-interrupted dimethylalkanes and particu-
larly the stereoisomers of 7,11-dimethylheptadecane and
7-methylheptadecane, taking synthetic advantage of the
procedure outlined above.
Resu lts a n d Discu ssion
Recently, we reported on a very efficient protocol to
perform the stereocontrolled reduction of tertiary prop-
argylic alcohols by an intramolecular hydride transfer
from a stereochemically defined benzyloxy group located
at the bis-homo propargylic position (Scheme 1).8 The
Syn th esis of Alk yl-Br a n ch ed Alk a n es. Our strategy
for the controlled synthesis of stereochemically defined
alkyl-substituted alkanes is based on the retrosynthetic
analysis outlined in Scheme 2. We considered the syn-
thesis of 1 from the bis-homopropargylic alcohol 4, that
in accordance with the above-mentioned reductive pro-
cedure may be obtained from the Co2(CO)6-acetylenic
diols 5. In this diastereomeric mixture, the only stereo-
chemical requirement is a defined configuration at the
benzyloxy position, that of the propargylic position being
irrelevant. Retrosynthetic cleavage of such carbinols
afforded, via an acetylide addition, the methyl ketone 6
as a potential precursor. The stereochemistry of the
necessary benzyloxy group could be secured through the
(1) (a) Dictionary of Natural Products; Chapman & Hall: New York,
1998; Vol. 11 (4th Suppl.). (b) Faulkner, D. J . Nat. Prod. Rep. 1999,
16, 155, and references therein.
(2) Mori, K. Tetrahedron 1989, 45, 3233, and references therein.
(3) Gries, R.; Gries, G.; Li, J .; Maier, C. T.; Lemmon, C. R.; Slessor,
K. N. J . Chem. Ecol. 1994, 20, 2501.
(4) Maier, C. T.; Gries, R.; Gries, G. J . Chem. Ecol. 1998, 24, 491.
(5) Gries, R.; Gries, G.; Borden, J . H.; Li, J .; Slessor, K. N.; King, G.
G. S.; Bowers, W. W.; West, R. J .; Underhill, E. W. Naturwissenschaften
1991, 78a, 315.
(6) Gries, R.; Gries, G.; Krannitz, S. H.; Li, J .; King, G. G. S.; Slessor,
K. N.; Borden, J . H.; Bowers, W. W.; West, R. J .; Underhill, E. W. J .
Chem. Ecol. 1993, 19, 1009.
(7) Shirai, Y.; Seki, M.; Mori, K. Eur. J . Org. Chem. 1999, 3139, 9.
(8) D´ıaz, D.; Mart´ın, V. S. Org. Lett. 2000, 2, 335.
10.1021/jo0055436 CCC: $19.00 © 2000 American Chemical Society
Published on Web 10/06/2000

Synthesis of Alkyl-Branched Alkanes
J . Org. Chem., Vol. 65, No. 23, 2000 7897
Sch em e 3a
Sch em e 4
a
Key: (a) Red-Al, THF, 0 °C, 93%; (b) (i) PhCH(OMe)2, CSA
(cat.), CH2Cl2, rt, (ii) DIBAL-H, CH2Cl2, 0 °C, 84% overall; (c) (i)
SO3‚Py, DMSO, Et3N, CH2Cl2, rt, (ii) MeMgCl, THF, -78 °C, (iii)
PCC, CH2Cl2, rt, 74% overall; (d) LiCtCC4H9-n, THF, -78 °C; (e)
(i) Co2(CO)8, CH2Cl2, rt; (ii) BF3‚OEt2, CH2Cl2, -20 °C, (iii) CAN,
acetone, 0 °C, 75% overall; (f) (i) H2, Pd/C, EtOAc, (ii) MsCl, Et3N,
CH2Cl2; 0 °C, (iii) LiAlH4, THF, reflux, 73% overall.
Sch em e 5a
2,3-epoxy alcohol 7 easily available by the use of the
Katsuki-Sharpless asymmetric epoxidation.9
The known epoxide 710 was regioselectively opened to
the corresponding 1,3-diol 8 using Red-Al as the reducing
agent (Scheme 3).11 To differentiate both hydroxyl groups
and to introduce the necessary benzyloxy group at the
secondary position, we protected the diol as the ben-
zylidene acetal. Reductive opening of the cyclic ether with
DIBAL-H provided the benzyl protected secondary alco-
hol 9 as the major regioisomer (5:1).12 To obtain the
necessary tertiary propargylic alcohol, the primary alco-
hol in 9 was oxidized to the corresponding aldehyde that
after addition of the suitable alkyl Grignard reagent and
new oxidation provided the desired methyl ketone 6. The
simple addition of the lithium acetylide derived from
1-hexyne provided the desired diastereomeric mixture 10.
Although the stereochemistry at the propargylic position
is irrelevant for our purposes, it should be pointed out
that a slight enrichment of one diastereosiomer was
obtained (ca. 1.5:1).
a
Key: (a) Red-Al, THF, 0 °C, 88%; (b) (i) DHP, CH2Cl2, OPCl3,
0 °C, (ii) PhCH2Br, NaH, n-Bu4NI (cat.), THF, rt, (iii) MeOH, HCl
(cat.), rt, 73% overall; (c) (i) SO3‚Py, DMSO, Et3N, CH2Cl2, rt, (ii)
MeMgCl, THF, -78 °C, (iii) PCC, CH2Cl2, rt, 76% overall; (d) (i)
LiCtCC4H9-n, THF, -78 °C, (ii) Co2(CO)8, CH2Cl2, rt, (iii)
BF3‚OEt2, CH2Cl2, -20 °C, (iv) CAN, acetone, 0 °C, 77% overall;
(e) (i) H2, Pd/C, EtOAc, rt, (ii) PhCH(OMe)2, CSA (cat.), CH2Cl2,
(iii) DIBAL-H, CH2Cl2, 0 °C, 81% overall; (f) (i) H2, Pd/C, EtOAc,
rt, (ii) MsCl, Et3N; CH2Cl2; 0 °C, (iii) LiAlH4, THF, reflux, 71%
overall.
our methodology to a complexed tertiary carbinol such
as 12 (Scheme 4). Thus, the synthesis of an additional
tertiary alcohol forces us to perform the first reductive
process over a substrate with an additional protected
hydroxyl group 14, this molecule being easily available
from the corresponding 2,3-epoxy alcohol 15 by a similar
methodology to that outlined earlier.
The application to the known epoxide 1513 (P ) Bn) of
a methodology similar to that described above yielded the
free alcohol 19 with the stereochemically well-defined
methyl group located at the R-position relative to the
triple bond (Scheme 5). Interestingly, it should be pointed
out that in this case we had to apply a different procedure
to locate the benzyloxy group at the secondary position
since the DIBAL-H reduction of the benzylidene deriva-
tive of 16 provided the primary benzyl ether as the major
product. Thus, we had to obtain 17 from 16 by a
consecutive series of protecting group manipulations,
namely monoprotection of the primary alcohol as the
THP-ether, benzyl ether formation of the secondary
carbinol and cleavage of the primary ether.
With the propargylic alcohol mixture 10 in our hands,
we were ready to apply our intramolecular reduction
procedure. We first complexed the carbon-carbon triple
bond as the corresponding Co2(CO)6-acetylene derivative
5. This Co-complex was then submitted to acidic treat-
ment with BF3‚OEt2 and further demetalated under
oxidative conditions, providing the bis-homopropargylic
alcohol 4 as the only detected stereoisomer. Finally, and
to obtain the natural compound, the acetylene was
hydrogenated to the saturated chain, and the hydroxyl
group was eliminated via the mesylation and further
hydride reduction to afford (S)-7-methylheptadecane (1)
[R]25 ) +0.29 (c 5.13, hexane) [lit.7 [R]25 ) +0.275 (c
D
D
5.02, hexane)].
Syn th esis of 3-Meth ylen e-In ter r u p ted Dia lk yl-
Br a n ch ed Alk a n es. The achievement of the enantio-
meric synthesis of 1 prompted us to speculate over the
iterative application in both directions of the above-
described reduction, taking a central benzyloxy group as
the stereochemical director. In this sense, the stereocon-
trolled synthesis of meso-2 could be envisioned from a
secondary alcohol such as 11, available by application of
The hydrogenation of 19 permitted simultaneously the
cleavage of the benzyl-protecting group and reduction of
the triple bond to the corresponding saturated chain. The
resulting diol was protected as the benzylidene derivative
that after reduction with DIBAL-H provided 20, having
the necessary secondary benzyloxy group (to induce a
new intramolecular reduction) and the free primary
(9) Katsuki, T.; Mart´ın, V. S. In Organic Reactions; Paquette, L.
A., et al., Eds.; J ohn Wiley & Sons: New York, 1996; Vol. 48, pp 1-299.
(10) Gao, Y.; Hanson, R. M.; Kluder, J . M.; Ko, S. Y.; Masamune,
H.; Sharpless, K. B. J . Am. Chem. Soc. 1987, 109, 5765.
(11) (a) Viti, S. M. Tetrahedron Lett. 1982, 23, 4541. (b) Ma, P.;
Mart´ın, V. S.; Masamune, S.; Sharpless, K. B.; Viti, S. M. J . Org. Chem.
1982, 47, 1378.
(12) Takano, S.; Akiyama, M.; Sato, S.; Ogasawara, K. Chem. Lett.
1983, 1593.
(13) Hirai, Y.; Chintani, M.; Yamazaki, T.; Momose, T. Chem. Lett.
1989, 1449.

7898 J . Org. Chem., Vol. 65, No. 23, 2000
D´ıaz and Mart´ın
Sch em e 6
excellent way to achieve the synthesis of alkyl branched
alkanes with perfect control of the stereochemistry. With
the application of this intramolecular reductive process
the enantiomeric synthesis has been accomplished of the
pheromone component of some species of Lambdina,
structurally characterized as methyl-substituted linear
alkanes. Although the presented methodology has been
described only for one enantiomeric series, the alternative
choice of the tartrate auxiliary in the Katsuki-Sharpless
asymmetric epoxidation step reaction for the synthesis
of the starting epoxy alcohols permits us to control the
absolute configuration in the final product. The applica-
tion of the described methodology could be a way to gain
access to the enantiomeric series of many other natural
compounds having alkyl-substituted hydrocarbons in
their structures.
Sch em e 7a
Exp er im en ta l Section
Ma ter ia ls a n d Meth od s. 1H and 13C NMR spectra were
recorded at 400 and 75 MHz, respectively, and chemical shifts
are reported relative to internal Me4Si. Optical rotations were
determined for solutions in chloroform or n-hexane. Column
chromatography was performed on Merck silica gel, 60 Å and
230-400 mesh. Compounds were visualized by use of UV light
and/or 2.5% phosphomolybdic acid in ethanol with heating.
All solvents were purified by standard techniques.14 Reactions
requiring anhydrous conditions were performed under argon.
Anhydrous magnesium sulfate was used for drying solutions.
P r ep a r a tion of (3S)-Un d eca n e-1,3-d iol (8). To a solution
of 710 (0.30 g, 1.61 mmol) in dry THF (8 mL) was slowly added
Red-Al (1.2 mL, 3.4 M solution in toluene, 4.03 mmol) at 0 °C
under argon. The reaction mixture was stirred for 2.5 h, after
which time TLC showed no remaining epoxide. Then water (3
mL) and HCl (5% w/v in water) (6 mL) were sequentially
added, and the mixture was stirred until clear phases were
reached (0.5 h). The phases were separated, and the aqueous
phase was extracted with Et2O. The combined organic phases
were washed with saturated aqueous NaHCO3 and brine,
dried, filtered, concentrated, and purified by column chroma-
a
Key: (a) H2, Pd/C, EtOAc, rt, 100%; (b) (i) MsCl, Et3N, CH2Cl2,
(ii) KOAc, 18-crown-6 (cat.), Be, reflux, (iii) MeOH, NaH, CH2Cl2,
0 °C, 77% overall; (c) (i) PhCH(OMe)2, CSA (cat.), CH2Cl2, (ii)
DIBAL-H, CH2Cl2, 0 °C 82% overall; (d) (i) SO3‚Py, DMSO, Et3N,
CH2Cl2, (ii) MeMgCl, THF, -78 °C, (iii) PCC, CH2Cl2, 0 °C, 75%
overall; (e) (i) LiCtCC4H9-n, THF, -78 °C; (ii) Co2(CO)8, CH2Cl2,
rt, (iii) BF3‚OEt2, CH2Cl2, -20 °C, (iv) CAN, acetone, 0 °C, 73%
overall; (f) (i) H2, Pd/C, EtOAc, rt, (ii) MsCl, Et3N; CH2Cl2; 0 °C,
(iii) LiAlH4, THF, reflux, 70% overall.
alcohol to homologate the chain. With the iteration of the
former sequence of reactions the free alcohol 11 was
obtained without any contamination of stereoisomers.
Finally, the reductive elimination of the hydroxyl group
provided meso-2, identical in all aspects to the natural
product.
Although it has been established that the bioactive
pheromone components are (S)-1 and meso-(2) our meth-
odology would also be ideal for the synthesis of the other
diastereoisomers of 2. Thus, addressing our attention
over the synthesis of (S,S)-3 should be easily resolved
by application of above-described method to the epimeric
alcohols 21 that should be available from 19 after
inversion of the configuration at the carbinol center
(Scheme 6).
tography to yield 8 (0.28 g, 93% yield) as a colorless oil: [R]25
D
1
) -0.25 (c 2.40, CHCl3); H NMR (CDCl3) δ 0.85 (t, J ) 6.3
Hz, 3H), 1.90-1.38 (br s, 11H), 1.38-1.50 (m, 3H), 1.52-1.72
(m, 2H), 3.30 (br s, 2H), 3.81 (m, 3H); 13C NMR (CDCl3) δ 14.12
(q), 22.62 (t), 25.53 (t), 29.24 (t), 29.55 (t), 29.63 (t), 31.84 (t),
37.74 (t), 38.21 (t), 61.50 (t), 72.29 (d); IR (film) υ˜max (cm-1
)
3347, 2926, 2855, 1466; MS m/z (relative intensity) 188 (M)+
(0.1), 187 (M - 1)+ (0.2), 141 (18), 83 (17), 75 (100). Anal. Calcd
for C11H24O2: C, 70.16; H, 12.85. Found: C, 70.16; H, 12.97.
P r ep a r a tion of (3S)-3-(P h en ylm eth oxy)u n d eca n -1-ol
(9). To a stirred solution of 8 (0.16 g, 0.85 mmol) in dry CH2-
Cl2 (8 mL) were sequentially added a catalytic amount of CSA
(21 mg, 0.085 mmol) and benzaldehydedimethyl acetal (179
µL, 1.17 mmol) at room temperature. The reaction mixture
was stirred for 1 h, after which time TLC showed complete
conversion to the benzylidene derivative. Then, Et3N was
added until pH ≈ 7, and the mixture was stirred for 5 min
and evaporated under reduced pressure.
To perform the necessary inversion at the secondary
carbinol center, the acetylenic alcohol 19 was submitted
to hydrogenation (Scheme 7). In one step, concomitant
benzyl ether cleavage and triple bond hydrogenation
provided the diol 22. Simultaneous mesylation of the diol
system and further treatment with sodium acetate
provided the corresponding diacetates with inverted
configuration at the secondary center. Basic hydrolysis
of both esters yielded the diol 23 as a pure stereoisomer,
verified by comparison with 22 and the corresponding
diacetates. After this point, an iterative application of the
series of reactions used above led to (7S,11S)-dimethyl-
heptadecane [(S,S)-3] [R]25D ) +1.63 (c 1.52, hexane) [lit.7
To a solution of the crude obtained in dry CH2Cl2 (6 mL)
was slowly added DIBAL-H (8.5 mL, 1 M solution in cyclo-
hexane, 8.5 mmol) at 0 °C. After this addition, the mixture
was allowed to warm to room temperature for a period of 15
min with stirring and diluted with CH2Cl2 (20 mL), and
aqueous HCl (5% w/v in water) (10 mL) was added. The
resulting mixture was extracted with CH2Cl2. The combined
organic layers were washed with saturated aqueous NaHCO3
and brine, dried, filtered, concentrated, and purified by column
chromatography to afford 9 (199 mg, 70% overall yield) as a
[R]22 ) +1.77 (c 1.41, hexane)].
D
Con clu sion s
The Lewis acid treatment of tertiary Co2(CO)6-prop-
argylic alcohols having a stereochemically defined ben-
zyloxy group at the γ-benzyl position yielded after cobalt
demetalation sec-dialkyl bis-homopropargylic alcohols in
good yields. The hydrogenation of the acetylene and the
reductive elimination of the alcohol group provided an
colorless oil: [R]25 ) +34.3 (c 2.92, CHCl3); 1H NMR (CDCl3)
D
(14) Armarego, W. L. F.; Perrin, D. D. Purification of Laboratory
Chemicals, 4th ed.; Butterworth-Heinemann: Oxford, 1996.

Synthesis of Alkyl-Branched Alkanes
J . Org. Chem., Vol. 65, No. 23, 2000 7899
δ 0.89 (t, J ) 6.6 Hz, 3H), 1.28 (br s, 13H), 1.48-1.83 (m, 3H),
2.15 (br s, 1H), 3.64 (m, 1H), 3.75 (m, 2H), 4.54 (dd, J ) 35.3,
11.4 Hz, 2H), 7.34 (m, 5H); 13C NMR (CDCl3) δ 14.1 (q), 22.7
(t), 25.1 (t), 29.3 (t), 29.6 (t), 29.8 (t), 31.9 (t), 33.5 (t), 36.0 (t),
60.6 (t), 70.9 (t), 78.4 (d), 127.7 (d), 127.8 (d), 128.0 (d), 128.4
(d), 138.5 (s); IR (film) υ˜max (cm-1) 3405, 2855, 1455, 1350, 1066;
MS m/z (relative intensity) 278 (M)+ (2), 260 (M - H2O)+ (7),
107 (28), 91 (100). Anal. Calcd for C18H30O2: C, 77.65; H, 10.86.
Found: C, 77.69; H, 10.71.
P r ep a r a tion of (4S)-4-(P h en ylm eth oxy)d od eca n -2-on e
(6). SO3-py complex (0.27 g, 1.69 mmol) was added to a stirred
mixture of 9 (150 mg, 0.54 mmol), Et3N (0.38 mL, 2.7 mmol),
dry DMSO (1.11 mL, 5.78 mmol), and dry CH2Cl2 (3 mL) at 0
°C. The reaction mixture was stirred until TLC showed
completion of the reaction (ca. 2 h). Then the mixture was
diluted with CH2Cl2, washed with brine, dried, filtered, and
concentrated, providing the aldehyde that was suitable for use
without further purification.
mixture was evaporated and the residue diluted with water
and extracted with Et2O. The combined organic solutions were
dried, filtered, and concentrated. Flash column chromatogra-
phy yielded 4 (69 mg, 75% yield overall) as a colorless oil:
[R]25 ) -22.7 (c 0.90, CHCl3); 1H NMR (CDCl3) δ 0.87 (t, J )
D
6.9 Hz, 3H), 0.89 (t, J ) 6.2 Hz, 3H), 1.16 (d, J ) 6.8 Hz, 3H),
1.27 (br s, 12H), 1.45 (m, 6H), 1.53 (t, J ) 6.7 Hz, 2H), 2.14 (t,
J ) 6.7 Hz, 2H), 2.50 (m, 2H), 3.75 (m, 1H); 13C NMR (CDCl3)
δ 13.6 (q), 14.1 (q), 18.3 (t), 21.9 (t), 22.0 (q), 22.6 (t), 24.0 (d),
25.4 (t), 29.3 (t), 29.6 (t), 29.7 (t), 31.1 (t), 31.9 (t), 37.4 (t),
44.6 (t), 71.4 (d), 82.0 (s), 84.5 (s); IR (film) υ˜max (cm-1) 3358,
2928, 2856, 2291, 1074; MS m/z (relative intensity) 266 (M)+
(5), 248 (M - H2O)+ (5), 153 (100). Anal. Calcd for C18H34O:
C, 81.13; H, 12.86. Found: C, 81.19; H, 12.57.
P r ep a r a tion of (7S)-7-Meth ylh ep ta d eca n e (1). A sus-
pension of the acetylene 4 (51 mg, 0.19 mmol) in AcOEt (2
mL) and 10% Pd-C (4 mg) was degassed at room temperature.
The mixture was vigorously stirred under H2 atmosphere for
2 h at room temperature. After removal of the catalyst by
filtration, the filtrate was concentrated, and the residue was
used without further purification.
To a mixture of the crude alcohol in dry CH2Cl2 (2 mL) and
Et3N (53 µL, 0.38 mmol) was added MeSO2Cl (22 µL, 0.29
mmol) at 0 °C. The solution was allowed to warm to room
temperature and stirred for 20 min. The reaction mixture was
quenched with brine (5 mL) and extracted with CH2Cl2. The
organic layer was washed with brine, dried, filtered and
concentrated under reduced pressure. The residue was used
in the next step without further purification.
To a solution of the crude aldehyde in THF (5.5 mL) was
added dropwise MeMgCl (0.24 mL, 3 M in THF, 0.70 mmol)
at -78 °C. After the mixture was stirred for 0.5 h, saturated
NH4Cl solution (5 mL) was added, and the resulting slurrywas
extracted with Et2O. The combined organic extracts were
dried, filtered, and concentrated. The residual oil was used
without further purification.
To a solution of the crude diastereomeric alcohols in dry
CH2Cl2 (6 mL) were sequentially added PCC (0.23 g, 1.08
mmol), powdered 4-Å molecular sieves, and a small amount
of NaOAc (ca. 10 mg). The heterogeneous mixture was stirred
for 4 h, filtered through a pad of silica gel, and concentrated.
The resulting viscous oil was purified by flash column chro-
matography to yield 6 (116 mg, 74% yield) as a colorless oil:
The crude mesylate was dissolved in dry THF (2 mL) and
added to a stirred suspension of LiAlH4 (7.5 mg, 0.19 mmol)
in dry THF (1 mL) at room temperature. The mixture was
refluxed for 12 h, after which time TLC showed complete
conversion to the saturated compound. Then, the reaction
mixture was cooled to 0 °C and quenched with wet Et2O (5
mL) and aqueous HCl (5%) (5 mL). The layers were separated,
and the aqueous solution was extracted with Et2O. The
combined organic layers were washed with saturated aqueous
NaHCO3 and brine, dried and concentrated. The residue
obtained was purified by column chromatography to furnish
[R]25 ) +15.2 (c 0.53, CHCl3); 1H NMR (CDCl3) δ 0.88 (t, J )
D
6.5 Hz, 3H), 1.26 (br s, 12H), 1.58 (m, 2H), 2.16 (s, 3H), 2.51
(dd, J ) 15.8, 4.8 Hz, 1H), 2.75 (dd, J ) 15.8, 7.5 Hz, 1H),
3.92 (dddd, J ) 6.0, 6.0, 6.0, 6.0 Hz, 1H), 4.51 (dd, J ) 10.6,
14.7 Hz, 2H), 7.30 (m, 5H); 13C NMR (CDCl3) δ 14.1 (q), 22.6
(t), 25.1 (t), 29.2 (t), 29.5 (t), 29.6 (t), 31.2 (q), 31.8 (t), 34.3 (t),
48.6 (t), 71.5 (t), 75.6 (d), 127.6 (d), 127.8 (d), 128.3 (d), 128.4
(d), 128.8 (d), 138.5 (s), 207.9 (s); IR (film) υ˜max (cm-1) 2926,
2233, 1721, 1357, 1070; MS m/z (relative intensity) 290 (M)+
(0.4), 152 (29), 107 (32), 91 (100). Anal. Calcd for C19H30O2:
C, 78.57; H, 10.41. Found: C, 78.52; H, 10.71.
pure 1 (35 mg, 73% yield overall) as a colorless oil: [R]25
)
D
1
+0.29 (c ) 5.13, hexane); H NMR (CDCl3) δ 0.84 (d, J ) 6.4
Hz, 3 H), 0.88 (t, J ) 6.8 Hz, 6 H), 1.00-1.40 (m, 29H); 13C
NMR (CDCl3) δ 14.09 (q), 19.69 (q), 22.68 (t), 27.04 (t), 27.08
(t), 29.35 (t), 29.48 (t), 29.66 (t), 29.70 (t), 30.03 (t), 31.92 (t),
31.95 (t), 32.74 (d), 37.09 (t); IR (film) υ˜max (cm-1) 2956, 2925,
1463, 725; MS m/z (relative intensity) 254 (M)+ (6), 239 (7),
168 (33), 112 (44), 57 (100). Anal. Calcd for C18H38: C, 84.95;
H, 15.05. Found: C, 84.98; H, 14.77.
P r ep a r a tion of (9S,7R)-7-Meth ylh ep ta d ec-5-yn -9-ol (4).
n-BuLi (0.22 mL, 1.9 M in hexanes, 0.41 mmol) was added to
a solution of 1-hexyne (51 µL, 0.44 mmol) in dry THF (1.5 mL)
at -78 °C. After the addition, the mixture was warmed to room
temperature for a period of 0.5 h. Then, this mixture was
cooled to -78 °C and a solution of 6 (100 mg, 0.34 mmol) in
dry THF (2.5 mL) was added dropwise. The mixture was
stirred at -78 °C for 1 h, whereupon it was quenched with
saturated NH4Cl solution (5 mL) and Et2O (10 mL). The
organic layer was washed with brine, dried, filtered, and
concentrated to give 10 as a mixture of diastereoisomers in
which one slightly predominated (ca. 1.5:1).
To a solution of 10 in dry CH2Cl2 (4 mL) was added Co2-
(CO)8 (151 mg, 0.44 mmol) at room temperature. The reaction
mixture was stirred at room temperature until TLC showed
complete conversion to the hexacarbonyldicobalt complex (ca.
1h). The mixture was concentrated through a pad of silica gel
and concentrated to yield a brown solid that was used without
any purification.
To a stirred solution of the crude Co2(CO)6 complex in dry
CH2Cl2 (4 mL) was slowly added BF3‚OEt2 (27 µL, 0.35 mmol)
at -20 °C. The reaction mixture was stirred for 10 min and
poured into a saturated aqueous NaHCO3 (10 mL) at 0 °C.
The resulting mixture was vigorously stirred for 15 min and
extracted with CH2Cl2. The combined organic layers were
washed with brine, dried, filtered, and concentrated to give
the Co2(CO)6 complex of 4 that was employed in the next step
without further purification.
To a stirred solution of the complexed acetylene in dry
acetone (4 mL) was added CAN (0.76 g, 0.25 mmol) in one
portion at 0 °C. The reaction mixture was stirred at 0 °C until
TLC showed completion of the reaction (ca. 5 min). The
P r ep a r a tion of (3R)-5-(P h en ylm eth oxy)p en ta n e-1,3-
d iol (16). The same procedure used above to obtain 8 from 7
was applied to 1513 on a 0.30 g (1.61 mmol) scale, yielding 16
(0.27 g, 88% yield) as a colorless oil: [R]25 ) +13.1 (c 0.45,
D
CHCl3); 1H NMR (CDCl3) δ 1.69-1.78 (m, 1H), 1.78-1.90 (m,
3H), 3.14 (br s, 2H), 3.68 (m, 2H), 3.81 (m, 2H), 4.07 (m, 1H),
4.51 (s, 2H), 7.32 (m, 5H); 13C NMR (CDCl3) δ 36.6 (t), 38.5
(t), 61.4 (t), 69.0 (t), 71.6 (d), 73.1 (t), 127.7 (d), 127.8 (d), 128.2
(d), 128.5 (d), 137.8 (s); IR (film) υ˜max (cm-1) 3384, 2925, 1656,
1453, 1091; MS m/z (relative intensity) 211 (M + 1)+ (1), 192
(6), 107 (63), 91 (100). Anal. Calcd for C12H18O3: C, 68.54; H,
8.63. Found: C, 68.54; H, 8.75.
P r ep a r a tion of (3R)-3,5-Bis(p h en ylm eth oxy)p en ta n -1-
ol (17). To a stirred solution of 16 (0.25 g, 1.19 mmol) in dry
CH2Cl2 (15 mL) were added 3,4-dihydro-2H-pyran (0.10 mL,
1.13 mmol) and a catalytic amount of OPCl3 at 0 °C. The
reaction was stirred at 0 °C until starting material was not
detected by TLC (ca. 4 h). Then, Et3N was added until pH ≈
7, and the reaction mixture was poured into brine at room
temperature. The mixture was extracted with CH2Cl2, and the
combined organic phases were dried, filtered, and concentrated
to give a mixture of mono and diprotected products, which was
used in the next step without further purification.
To a stirred suspension of NaH (60% in mineral oil, 57.2
mg, 1.43 mmol) in dry THF (4 mL), at 0 °C were sequentially
and slowly added a solution of the crude product in THF (1

7900 J . Org. Chem., Vol. 65, No. 23, 2000
D´ıaz and Mart´ın
mL), a catalytic amount of Bu4NI, and benzyl bromide (0.2 mL,
1.67 mmol). The reaction mixture was stirred at room tem-
perature for 24 h. Then, the mixture was diluted with Et2O,
washed with brine, dried, and concentrated.
) -7.9 (c 0.76, CHCl3); 1H NMR (CDCl3) δ 0.88 (m, 6H), 1.26
(br s, 10H), 1.58-1.94 (m, 5H), 2.33 (br s, 1H), 3.74 (m, 2H),
3.80 (m, 1H), 4.54 (dd, J ) 11.4, 11.4 Hz, 2H), 7.33 (m, 5H);
13C NMR (CDCl3) δ 14.1 (q), 20.0 (q), 23.2 (t), 27.0 (t), 29.4 (d),
29.6 (t), 31.9 (t), 36.2 (t), 38.5 (t), 41.5 (t), 60.5 (t), 70.9 (t),
76.5 (d), 127.4 (d), 127.7 (d), 127.9 (d), 128.4 (d), 138.4 (s); IR
(film) υ˜max (cm-1) 3387, 2925, 1719, 1454, 1069; MS m/z
(relative intensity) 292 (M)+ (2), 147 (11), 107 (27), 92 (14), 91
(100). Anal. Calcd for C19H32O2: C, 78.03; H, 11.03. Found:
C, 78.07; H, 11.06.
To a stirred mixture of the crude product in MeOH (4 mL)
was added concentrated HCl until pH ≈ 1 at room tempera-
ture. The reaction mixture was stirred at room temperature
until TLC showed completion of the reaction (ca. 5 min),
whereupon it was quenched with Et3N until pH ≈ 7. The
reaction mixture was stirred for 5 min, concentrated under
reduced pressure and the crude residue obtained was chro-
matographed on a column to yield 17 (0.26 g, 73% yield) as a
colorless oil: [R]25D ) +2.6 (c 0.89, CHCl3); 1H NMR (CDCl3) δ
1.77-2.06 (m, 4H), 2.32 (br s, 1H), 3.59 (m, 2H), 3.78 (m, 2H),
3.81 (m, 1H), 4.49 (s, 2H), 4.55 (s, 2H), 7.33 (m, 10H); 13C NMR
(CDCl3) δ 34.1 (t), 36.3 (t), 60.2 (t), 66.7 (t), 71.4 (t), 73.1 (t),
75.4 (d), 127.7 (d), 127.8 (d), 127.9 (d), 128.2 (d), 128.4 (d), 128.5
(d), 138.3 (s); IR (film) υ˜max (cm-1) 3418, 1643, 1362, 1091, 799;
MS m/z (relative intensity) 301 (M + 1)+ (0.1), 194 (12), 107
(26), 91 (100). Anal. Calcd for C19H24O3: C, 75.97; H, 8.05.
Found: C, 75.99; H, 7.92.
P r ep a r a tion of (7S,11S,9R)-7,11-Dim eth ylh ep ta d ec-5-
yn -9-ol (11). The same procedure used above to obtain 4 from
9 was applied to 20 on an 80 mg (0.28 mmol) scale, yielding
11 (49 mg, 57% yield) as a colorless oil: [R]25D ) +30.3 (c 0.53,
1
CHCl3); H NMR (CDCl3) δ 0.88 (m, 9H), 1.16 (d, J ) 6.8 Hz,
3H), 1.26 (br s, 13H), 1.33-1.59 (m, 6H), 2.15 (t, J ) 5.2 Hz,
2H), 2.40 (br s, 1H), 2.53 (m, 1H), 3.86 (m, 1H); 13C NMR
(CDCl3) δ 13.56 (q), 14.07 (q), 18.34 (t), 19.16 (q), 21.93 (t),
22.03 (q), 22.64 (t), 23.99 (d), 26.90 (t), 28.97 (d), 29.59 (t), 31.09
(t), 31.89 (t), 37.93 (t), 44.99 (t), 45.46 (t), 69.15 (d), 82.08 (s),
84.41 (s); IR (film) υ˜max (cm-1) 3375, 2927, 2232, 1462, 1378;
MS m/z (relative intensity) 280 (M)+ (3), 191 (17), 153 (100).
Anal. Calcd for C19H36O: C, 81.36; H, 12.94. Found: C, 81.35;
H, 12.58.
P r ep a r a tion of (4S)-4,6-Bis(p h en ylm eth oxy)h exa n -2-
on e (18). The same procedure used above to obtain 6 from 9
was applied to 17 on a 0.24 g (0.80 mmol) scale, yielding 18
(0.19 g, 76% yield) as a colorless oil: [R]25 ) -6.1 (c 0.99,
P r ep a r a tion of (7S,11R)-7,11-Dim eth ylh ep ta d eca n e
(m eso-2). The same procedure used above to obtain 1 from 4
was applied to 11 on a 40 mg (0.14 mmol) scale, yielding
meso-2 (27 mg, 71% yield overall) as colorless oil: 1H NMR
(CDCl3) δ 0.83-1.01 (m, 12H), 1.26 (m, 28H); 13C NMR (CDCl3)
δ 14.1 (q), 19.7 (q), 22.7 (t), 24.4 (t), 27.0 (t), 29.7 (t), 31.9 (t),
32.8 (d), 37.1 (t), 37.4 (t); IR (film) υ˜max (cm-1) 2956, 2925, 2855,
1463, 1377, 725; MS m/z (relative intensity) 288 (M)+ (3), 183
(26), 111 (21), 57 (100). Anal. Calcd for C19H40: C, 84.99; H,
15.01. Found: C, 84.99; H, 14.70.
D
CHCl3); 1H NMR (CDCl3) δ 1.86 (m, 2H), 2.14 (s, 3H), 2.61
(dd, J ) 16.0, 5.2 Hz, 1H), 2.77 (dd, J ) 16.0, 7.2 Hz, 1H),
3.61 (m, 2H), 4.12 (m, 1H), 4.49 (m, 4H), 7.30 (m, 10H); 13C
NMR (CDCl3) δ 31.0 (q), 34.5 (t), 48.8 (t), 66.5 (t), 71.8 (t), 73.0
(t), 73.1 (d), 127.6 (d), 127.7 (d), 127.8 (d), 128.1 (d), 128.3 (d),
128.4 (d), 128.5 (d), 138.1 (s), 207.4 (s); IR (film) υ˜max (cm-1
)
2861, 1716, 1496, 1361, 799; MS m/z (relative intensity) 294
(M - H2O)+ (0.7), 148 (11), 115 (28), 91 (100). Anal. Calcd for
C
20H24O3: C, 76.89; H, 7.74. Found: C, 76.85; H, 7.78.
P r ep a r a tion of (3R,5R)-5-Meth yl-1-(p h en ylm eth oxy)-
P r epar ation of (5S,3R)-5-Meth ylu n decan e-1,3-diol (22).
To a solution of 19 (0.20 g, 0.7 mmol) in AcOEt (7 mL) was
added 10% Pd-C (20 mg) at room temperature. The resulting
suspension was vigorously stirred under an atmosphere of H2
(1 atm) for 2 h at room temperature. After removal of the
catalyst by filtration, the filtrate was concentrated, and the
residue was purified by flash chromatography to yield 22 (0.14
g, 100% yield) as a colorless oil: [R]25D ) +6.7 (c 0.97, CHCl3);
1H NMR (CDCl3) δ 0.88 (m, 6H), 1.26 (br s, 10H), 1.38-1.70
(m, 5H), 2.34 (br s, 2H), 3.86 (m, 2H), 3.97 (m, 1H); 13C NMR
(CDCl3) δ 14.1 (q), 19.3 (q), 22.6 (t), 26.9 (t), 29.0 (d), 29.6 (t),
31.9 (t), 37.7 (t), 39.1 (t), 45.4 (t), 61.8 (t), 69.9 (d); IR (film)
υ˜max (cm-1) 3350, 2956, 2855, 1463, 1055; MS m/z (relative
intensity) 201 (M - 1)+ (0.3), 155 (15), 112 (43), 97 (11), 75
(100). Anal. Calcd for C12H26O2: C, 71.23; H, 12.95. Found:
C, 71.32; H, 12.87.
P r ep a r a tion of (3S,5S)-5-Meth ylu n d eca n e-1,3-d iol (23).
To a solution of 22 (0.13 g, 0.64 mmol) in dry CH2Cl2 (6.5 mL)
were sequentially added Et3N (0.18 mL, 1.28 mmol) and
MeSO2Cl (76 µL, 0.96 mmol) at 0 °C. The reaction mixture
was allowed to warm to room temperature and stirred for 30
min, whereupon it was quenched with brine (10 mL) and
extracted with CH2Cl2. The organic layer was washed with
brine, dried, filtered, and concentrated. The resulting residue
was used without any further purification.
To a suspension of KOAc (127 mg, 1.28 mmol) in benzene
(3 mL) were sequentially added the crude dimesylate dissolved
in benzene (5 mL) and 18-crown-6 (342 mg, 1.28 mmol) at room
temperature. The mixture was refluxed with vigorous stirring
for 12 h. The reaction mixture was cooled to room temperature,
poured into an ice-cooled saturated NH4Cl solution (10 mL),
and extracted with AcOEt. The combined organic layers were
washed with brine, dried, and concentrated to yield a crude
diacetate that was used in the next step without purification.
To a suspension of NaH (77 mg, 60% in mineral oil, 1.92
mmol) in dry CH2Cl2 (5 mL) was slowly added dry MeOH (0.16
mL, 3.84 mmol) at 0 °C. The mixture was stirred for 10 min,
and a solution of the crude diacetate dissolved in CH2Cl2 (2
mL) was added dropwise. The mixture was allowed to warm
to room temperature and stirred for 1 h. A saturated NH4Cl
solution (5 mL) was added at 0 °C, and the mixture was
u n d ec-6-yn -3-ol (19). The same procedure used above to
obtain 6 from 9 was applied to 18 on a 0.18 g (0.58 mmol)
scale, yielding 19 (0.13 g, 77% yield overall) as a colorless oil:
[R]25 ) -17.9 (c 0.61, CHCl3); 1H NMR (CDCl3) δ 0.89 (t, J )
D
7.1 Hz, 3H), 1.16 (d, J ) 6.8 Hz, 3H), 1.34-1.54 (m, 5H), 1.60-
1.79 (m, 3H), 2.14 (dd, J ) 5.0, 5.0 Hz, 2H), 2.53 (m, 1H), 3.15
(br s, 1H), 3.68 (m, 2H), 3.97 (m, 1H), 4.52 (s, 2H), 7.32 (m,
5H); 13C NMR (CDCl3) δ 13.6 (q), 18.4 (t), 21.7 (q), 21.9 (t),
23.2 (d), 31.1 (t), 36.5 (t), 44.5 (t), 68.6 (t), 69.7 (d), 73.2 (t),
81.4 (s), 84.5 (s), 127.6 (d), 127.8 (d), 128.2 (d), 128.4 (d), 138.1
(s); IR (film) υ˜max (cm-1) 3405, 2931, 2232, 1659, 1453, 1097,
782; MS m/z (relative intensity) 288 (M)+ (0.8), 159 (23), 153
(13), 91 (100). Anal. Calcd for C19H28O2: C, 79.12; H, 9.78.
Found: C, 79.13; H, 9.95.
P r ep a r a tion of (5S,3R)-5-Meth yl-3-(p h en ylm eth oxy)-
u n d eca n -1-ol (20). To a solution of 19 (0.12 g, 0.42 mmol) in
EtOAc (4 mL) was added 10% Pd-C (12 mg) at room temper-
ature. The resulting suspension was vigorously stirred under
an atmosphere of H2 (1 atm) for 2 h at room temperature. After
removal of the catalyst by filtration through a small pad of
Celite, the filtrate was concentrated and the residue used
without further purification.
To a solution of the crude diol in dry CH2Cl2 (4 mL) were
sequentially added a catalytic amount of CSA (9.8 mg, 0.04
mmol) and benzaldehydedimethyl acetal (84 µL, 0.55 mmol)
at room temperature. The reaction mixture was stirred for 1
h after which time TLC showed complete reaction. Then, Et3N
was added until pH ≈ 7, stirred for 5 min, and evaporated
under reduced pressure. The residue was used without further
purification.
To a solution of the crude benzylidene derivative obtained
in dry CH2Cl2 (3 mL) was slowly added DIBAL-H (4 mL, 1 M
solution in cyclohexane, 4 mmol) at 0 °C. The reaction mixture
was allowed to warm to room temperature over a period of 15
min. The mixture was diluted with CH2Cl2 (10 mL), and
aqueous HCl (5%) (5 mL) was added. The resulting mixture
was extracted with CH2Cl2. The combined organic layers were
washed with saturated aqueous NaHCO3 and brine, dried,
filtered, concentrated and purified by column chromatography
to yield 20 (98 mg, 81% yield overall) as a colorless oil: [R]25
D

Synthesis of Alkyl-Branched Alkanes
J . Org. Chem., Vol. 65, No. 23, 2000 7901
extracted with CH2Cl2. The combined extracts were washed
with brine, dried, filtered, concentrated, and purified by
column chromatography to yield 23 (99 mg, 77% overall yield)
P r ep a r a tion of (9S,11S,7R)-7,11-Dim eth ylh ecta d ec-5-
yn -9-ol (26). The same procedure used above to obtain 4 from
6 was applied to 25 on a 61 mg (0.2 mmol) scale, yielding 26
as a colorless oil: [R]25 ) -5.1 (c 0.48, CHCl3); 1H NMR
(41 mg, 73% yield overall) as a colorless oil: [R]25 ) -22.4 (c
D
D
0.18, CHCl3); 1H NMR (CDCl3) δ 0.89 (m, 9H), 1.16 (d, J ) 6.8
Hz, 3H), 1.26 (br s, 13H), 1.33-1.82 (m, 6H), 2.15 (t, J ) 5.8
Hz, 2H), 2.52 (m, 2H), 3.85 (m, 1H);13C NMR (CDCl3) δ 13.58
(q), 14.09 (q), 18.36 (t), 20.36 (q), 21.95 (t), 21.99 (q), 22.66 (t),
24.01 (d), 26.79 (t), 29.33 (d), 29.68 (t), 31.09 (t), 31.92 (t), 36.53
(t), 44.97 (t), 45.20 (t), 69.58 (d), 82.11 (s), 84.51 (s); IR (film)
υ˜max (cm-1) 3380, 2856, 2232, 1598, 1071; MS m/z (relative
intensity) 280 (M)+ (3), 205 (15), 153 (100). Anal. Calcd for
(CDCl3) δ 0.88 (m, 6H), 1.26 (br s, 10H), 1.38 (m, 2H), 1.52-
1.77 (m, 3H), 2.33 (br s, 2H), 3.87 (m, 2H), 3.97 (m, 1H); 13C
NMR (CDCl3) δ 14.0 (q), 20.2 (q), 22.6 (t), 26.8 (t), 29.2 (d),
29.6 (t), 31.9 (t), 36.8 (t), 38.4 (t), 45.4 (t), 61.8 (t), 70.1 (d); IR
(film) υ˜max (cm-1) 3346, 2955, 2855, 1463, 1055; MS m/z
(relative intensity) 185 (M - HO)+ (0.9), 157 (12), 112 (37), 83
(28), 75 (100). Anal. Calcd for C12H26O2: C, 71.23; H, 12.95.
Found: C, 71.34; H, 13.14.
P r ep a r a t ion of (3S,5S)-5-Met h yl-3-(p h en ylm et h oxy)-
u n d eca n -1-ol (24). The same procedure used above to obtain
9 from 8 was applied to 23 on a 81 mg (0.4 mmol), yielding 24
C
19H36O: C, 81.36; H, 12.94. Found: C, 81.41; H, 12.74.
P r epar ation of (7S,11S)-7,11-Dim eth ylh eptadecan e (3).
(94 mg, 82% overall yield) as a colorless oil: [R]25 ) +36.5 (c
The same procedure used above to obtain 4 from 6 was applied
to 26 on a 31 mg (0.11 mmol) scale, yielding 3 (21 mg, 70%
yield overall) as a colorless oil: [R]25D ) +1.63 (c 1.52, hexane);
1H NMR (CDCl3) δ 0.83-1.15 (m, 12H), 1.26 (m, 28H); 13C
NMR (CDCl3) δ 14.1 (q), 19.6 (q), 22.7 (t), 24.5 (t), 27.3 (t),
D
0.62, CHCl3); 1H NMR (CDCl3) δ 0.88 (t, J ) 5.6 Hz, 6H), 1.26
(br s, 11H), 1.48 (m, 2H), 1.69 (m, 1H), 1.89 (m, 1H), 3.70-
3.85 (m, 3H), 4.54 (dd, J ) 28.9, 10.6 Hz, 2H), 7.33 (m, 5H);
13C NMR (CDCl3) δ 14.1 (q), 19.9 (q), 22.7 (t), 26.9 (t), 29.2 (d),
29.6 (t), 31.9 (t), 35.8 (t), 37.5 (t), 41.0 (t), 60.7 (t), 70.7 (t),
77.0 (d), 127.7 (d), 127.9 (d), 128.4 (d), 128.5 (d), 128.6 (d), 138.3
(s); IR (film) υ˜max (cm-1) 3388, 2926, 1454, 1377, 1056; MS m/z
(relative intensity) 292 (M)+ (0.4), 247 (5), 107 (17), 92 (11),
91 (100). Anal. Calcd for C19H32O2: C, 78.03; H, 11.03. Found:
C, 78.09; H, 10.89.
29.7 (t), 31.9 (t), 32.8 (d), 37.1 (t), 37.4 (t); IR (film) υ˜max (cm-1
)
2956, 2855, 1463, 1377, 725; MS m/z (relative intensity) 288
(M)+ (3), 183 (25), 112 (40), 71 (85), 57 (100). Anal. Calcd for
C
19H40: C, 84.99; H, 15.01. Found: C, 84.88; H, 14.83.
Ack n ow led gm en t. We thank the DGES (PB98-
P r ep a r a t ion of (4S,6S)-6-Met h yl-4-(p h en ylm et h oxy)-
d od eca n -2-on e (25). The same procedure used above to obtain
6 from 9 was applied to 24 on a 90 mg (0.31 mmol) scale,
0443-C02-01) of Spain and FEDER (1FD97-0747-C04-
01) for support of this research. D.D. thanks the M.E.C.
of Spain for an F.P.I. fellowship. Many thanks are also
given to Dr. Toma´s Mart´ın for his helpful discussions
and suggestions.
yielding 17 (71 mg, 75% yield overall) as a colorless oil: [R]25
D
) +8.7 (c 0.36, CHCl3); 1H NMR (CDCl3) δ 0.87 (m, 6H), 1.26
(br s, 10H), 1.56 (m, 3H), 2.16 (s, 3H), 2.52 (dd, J ) 15.8, 4.7
Hz, 1H), 2.72 (dd, J ) 15.8, 7.3 Hz, 1H), 3.97 (m, 1H), 4.50 (s,
2H), 7.31 (m, 5H); 13C NMR (CDCl3) δ 14.1 (q), 20.1 (q), 22.7
(t), 26.8 (t), 29.5 (d), 29.6 (t), 31.2 (q), 31.9 (t), 36.9 (t), 42.2 (t),
48.8 (t), 71.4 (t), 74.1 (d), 127.6 (d), 127.7 (d), 127.9 (d), 128.3
(d), 128.4 (d), 138.4 (s), 207.9 (s); IR (film) υ˜max (cm-1) 2955,
2855, 1721, 1454, 1069; MS m/z (relative intensity) 304 (M)+
(0.1), 198 (11), 180 (19), 107 (26), 91 (100). Anal. Calcd for
Su p p or t in g In for m a t ion Ava ila b le: 1H NMR and 13C
NMR spectra for all new compounds described in the Experi-
mental Section. This information is available free of charge
via the Internet at http://pubs.acs.org.
C
20H32O2: C, 78.90; H, 10.59. Found: C, 78.72; H, 10.49.
J O0055436