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Helvetica Chimica Acta ± Vol. 82 (1999)
dried (Na2SO4) and evaporated. The light yellow oil was submitted to CC (hexane/AcOEt 9:1): 4 (20.8 g, 68%).
1H-NMR: 6.64 (dd, J 10, 16, H C(1)); 6.06 (d, J 16, H C(2)); 5.49 (br. s, H C(3')); 2.54 (t, J 7.2,
CH2(4)); 2.27 (d, J 10, H C(1')); 2.08 (m, 2 H); 1.3 ± 1.1 (m, 7 H); 0.94 (t, J 7, Me(6)); 0.92 (s, Me C(6');
0.85 (s, Me C(6')). Anal. calc. for C15H24O (220.35): C 81.76, H 10.98; found: C 81.82, H 10.95.
1-(2,6,6-Trimethylcyclohex-2-enyl)hex-1-en-3-ol (7; 4 stereoisomers). Reduction of 4 (33 g, 0.15 mol) with
NaBH4 in MeOH at 08 gave 7 (32 g, 93%) as a 1:1 mixture of two racemic diastereoisomers. GC (corresponding
acetates): 3 peaks in a 1:1:2 ratio; tR 24.61, 24.78, 24.93. 1H-NMR: 5.44 (m, 3 olef. H); 4.08 (m, H C(3)); 1.0 ±
2.2 (m, 12 H); 0.92 (t, J 7, Me(6)); 0.88 (s, Me C(2')); 0.83, 0.81 (2s, Me C(2') of the two diastereoisomers).
Anal. calc. for C15H26O (222.37): C 81.02, H 11.78; found: C 80.97, H 11.85.
Enzymic Acetylation of Racemic 7 (4 stereoisomers). A mixture of 7 (32 g, 0.14 mol), lipase PS
t
(Pseudomonas cepacia; 10 g), and vinyl acetate (48 ml) in BuOMe (300 ml) was stirred at r.t. for 24 h. After
filtration and evaporation, residue was submitted to CC (hexane/AcOEt 7:3). The first eluted fractions
provided the acetates 10c,d (13.9 g, 38%). GC: 1:1 mixture of the two enantiomerically pure diastereoisomers
10c and 10d, i.e. 2nd and 3rd peaks; tR 24.78, 24.93. 1H-NMR: 5.3 ± 5.6 (m, 3 olef. H); 5.20 (m, H C(3)); 1.8 ±
2.2 (m, 5 H); 1.0 ± 1.8 (m, 10 H); 0.85 ± 1.05 (m, 6 H); 0.80 (s, Me C(2')). Anal. calc. for C17H28O2 (264.41):
C 72.22, H 10.67; found: C 72.18, H 10.72.
The last eluted fractions gave the unreacted alcohol stereoisomers 7a,b (16.7 g, 50%), which were
acetylated with Ac2O in pyridine prior to epoxidation. GC (acetates): 1:1 mixture; 1st and 3rd peaks; tR 24.61,
24.93.
Epoxidation of 1-(2,6,6-Trimethylcyclohex-2-enyl)hex-1-en-3-ol Acetates: 1-(1,3,3-Trimethyl-7-oxabicy-
clo[4.1.0]hept-2-yl)hex-1-en-3-ol Acetates (11a ± d). In separate experiments, the 1:1 mixture of enantiomeri-
cally pure 10c,d (10 g, 0.04 mol) and the 1:1 mixture of the acetate derivatives (10 g, 0.04 mol) of 7a,b was
epoxidized with 70% 3-chloroperbenzoic acid (14.8 g, 0.06 mol) in CH2Cl2 (500 ml) at 08. Each mixture was
stirred for 2 h, and then filtered, the filtrate washed first with sat. NaHCO3, soln. and then with sat. NaHSO3
soln., dried (Na2SO4) and evaporated, and the residue submitted to CC (hexane/AcOEt 7:3). Starting from
10c,d, 11c (1st eluted; 3.81 g, 34%) and 11d (2nd eluted; 3.25 g, 29%), and starting from 7a,b, 11a (1st eluted;
3.47 g, 31%) and 11b (2nd eluted; 3.02 g, 27%) were obtained.
Data of 11c: [a]2D0 130 (c 1.25, CHCl3). H-NMR: 5.64 (dd, J 10, 15, H C(1)); 5.49 (dd, J 7, 15,
1
H
C(2)); 5.25 (q, J 7, H C(3)); 3.05 (m, H C(6')); 2.05 (s, MeCOO); 1.3 ± 2.0 (m, 9 H); 1.24 (s, Me C(1');
0.93 (t, J 7, Me(6)); 0.89 (s, Me C(3')); 0.73 (s, Me C(3')).
1
Data of 11d: [a]2D0
C(2)); 5.24 (q, J 7,
38 (c 1.05, CHCl3). H-NMR: 5.68 (dd, J 10, 15, H C(1)); 5.42 (dd, J 7, 15,
H
H C(3)); 3.05 (m, H C(6')); 2.05 (s, MeCOO); 1.25 ± 2.0 (m, 9 H); 1.22
(s, Me C(1')); 0.93 (t, J 7, Me(6)); 0.87 (s, Me C(3')); 0.73 (s, Me C(3')).
Data of 11a: [a]2D0
80 (c 1.31, CHCl3). 1H-NMR: in accordance with that of enantiomer 11c.
Data of 11b: [a]D20 19 (c 1.7, CHCl3). H-NMR: in accordance with that of enantiomer 11d.
Deoxygenation of Diastereoisomers 11a ± d: 1-(2,6,6-Trimethylcyclohex-2-en-1-yl)hex-1-en-3-ol Acetates
(10a ± d). In separate experiments, stereoisomers 11a ± d were submitted to deoxygenation according to the
following procedure: To a stirred mixture of 11a ± d (2.0 g, 0.007 mol), AcOH (25 ml), and NaOAc (1.6 g,
0.02 mol), NaI (2.2 g, 0.015 mol) was added at r.t. After 1 h, each mixture was diluted with hexane/AcOEt 1:1
and filtered, the filtrate washed with H2O and sat. NaHCO3 soln., dried (Na2SO4), and evaporated, and the
residue purified by CC (hexane/AcOEt 7:3) 10a ± d, resp.
1
Data of 10a: 1.20 g (65%). GC: 1st peak; tR 24.61; ee >99%, de 71%. [a]D20
165 (c 0.11, CHCl3).
1H-NMR: 5.52 (dd, J 9, 15, H C(1)); 5.40 (m, H C(3')); 5.34 (dd, J 7, 15, H C(2)); 5.20 (q, J 7,
H
C(3)); 2.10 (d, J 9, H C(1')); 2.03 (s, MeCOO); 1.99 (m, 1 H); 1.1 ± 1.7 (m, 10 H); 0.92 (t, J 7, Me(6));
0.88 (s, Me C(6')); 0.80 (s, Me C(6')).
Data of 10b: 1.10 g (60%). GC: 3rd peak; tR 24.93; ee >99%, de 90%. [a]2D0 105 (c 0.11, CHCl3).
1H-NMR: 5.51 (dd, J 9, 15, H C(1)); 5.40 (m, H C(3')); 5.35 (dd, J 7, 15, H C(2)); 5.21 (q, J 7,
H
C(3)); 2.10 (d, J 9, H C(1')); 2.04 (s, MeCOO); 2.00 (m, 1 H); 1.1 ± 1.7 (m, 10 H); 0.93 (t, J 7, Me(6));
0.90 (s, Me C(6')); 0.81 (s, Me C(6')).
Data of 10c: 1.33 g (72%). GC: 2nd peak; tR 24.78; ee >99%, de 91%. [a]2D0 254 (c 3.6, CHCl3).
1H-NMR: in accordance with that of enantiomer 10a.
Data of 10d: 1.26 g (68%). GC: 3rd peak; tR 24.93 min; ee >99%, de >99%. [a]D20
1H-NMR: in accordance with that of enantiomer 10b.
167 (c 2.9, CHCl3).
Hydrogenation of Racemic 7 (4 stereoisomers) and of the 1 :1 Mixture 7a,b: cis- and trans-1-(2,2,6-
Trimethylcyclohexyl)hexan-3-ol (2 and 3, resp.). In separate experiments, racemic 7 and the 1 :1 mixture 7a,b in
AcOH were hydrogenated in the presence of 10% Pd/C (30% w/w) at r.t. and at 3 atm. Each mixture was