A. M. Hooper et al. / Tetrahedron Letters 48 (2007) 5991–5994
5993
choice, use of pheromone traps and treatment thresholds.
HGCA Project Report No. 363, 2005.
(2S,7R)-4 (2R,7S)-4
2. Barnes, H. F. In Gall Midges of Economic importance.
Volume VII. Cereal Crops; Crosby Lockwood & Son Ltd:
London, 1956; pp 57–82.
3. Oakley, J. N.; Cumbleton, P. C.; Corbett, S. J.; Saunders,
P.; Green, D. I.; Young, J. E. B.; Rodgers, R. Crop Prot.
1998, 17, 145–149.
(2S,7S)-4
(2R,7R)-4
4. Gries, R.; Gries, G.; Khaskin, G.; King, S.; Olfert, O.;
Kaminski, L-A.; Lamb, R.; Bennett, R. Naturwissenschaf-
ten 2000, 87, 450–454.
5. Bruce, T. J. A.; Hooper, A. M.; Ireland, L.; Jones, O. T.;
Martin, J. L.; Smart, L. E.; Oakley, J.; Wadhams, L. J.
Pest Manag. Sci. 2007, 63, 49–56.
6. Connon, S. J.; Blechert, S. Angew. Chem., Int. Ed. 2003,
42, 1901–1923.
7. Lee, C. W.; Grubbs, R. H. J. Org. Chem. 2001, 66, 7155–
7158.
8. Delgado, M.; Martin, J. D. J. Org. Chem. 1999, 64, 4798–
4816.
9. Evans, P. A.; Cui, J.; Buffone, G. P. Angew. Chem., Int.
Ed. 2003, 42, 1734–1737.
10. Hoye, T.; Promo, M. A. Tetrahedron Lett. 1999, 40, 1429–
1432.
11. Postema, M. D.; Piper, J. L. Tetrahedron Lett. 2002, 43,
7095–7099.
12. Boiteau, J.-G.; Van de Weghe, P.; Eustache, J. Tetra-
hedron Lett. 2001, 42, 239–242.
(2S,7S)-4
13. Enantioselective GC was performed using a b-cyclodextrin
GC column, 30 m · 0.32 mm id · 25 lm film thickness,
40–180 ꢁC at 3 ꢁC minꢀ1 with cold on-column injection.
Samples were compared with standards of the four
possible isomers prepared biotechnologically with a Pseu-
domonas cepaciae lipase.3 Standard GC analysis was
performed using an HP-1 column, 50 m · 0.32 mm
id · 0.52 lm film thickness, 40–150 ꢁC at 5 ꢁC minꢀ1 and
(2S,7R)-4
(2R,7S)-4
(2R,7R)-4
150–250 ꢁC at 10 ꢁC minꢀ1
.
14. Kazlauskas, R. J.; Weissfloch, A. N. E.; Rappaport, A. T.;
Cuccia, L. A. J. Org. Chem. 1991, 56, 2656–2665.
15. Sigma–Aldrich.
36
Figure 1. Enantioselective gas chromatograms of a mixture of the four
isomers of 2,7-diacetoxynonane (4) (above) and (below) the diacet-
oxynonane mixture produced after silicon-tethered RCM of silaketal
(S)-2c.
16. Methodology for the synthesis of (2S,7S)-1.
Pyridine (0.34 ml, 4.2 mmol) and a small spatula of
DMAP were added to a solution of di-t-butylsilyl bis(tri-
fluoromethanesulfonate) (0.65 ml, 2.0 mmol) in dry THF
(10 ml) in a flame-dried flask at room temperature. The
solution was cooled to ꢀ78 ꢁC and a solution of (S)-5-
hexen-2-ol (0.24 ml, 2 mmol) in dry THF (5 ml) at ꢀ78 ꢁC
was added dropwise via a cannula. The reaction was
warmed to room temperature over 5 h and a solution of
1,4-pentadien-3-ol (0.19 ml, 2 mmol) in dry THF (1 ml)
was added dropwise. The mixture was stirred overnight,
concentrated in vacuo and filtered through a pad of
neutral alumina to yield 540 mg of crude (S)-2c. To a
solution of the crude product (300 mg, 0.93 mmol) in dry
CH2Cl2 (40 ml) was added a solution of Grubbs’ catalyst
yield of 22% in 99% ee and 94% de (Fig. 1). Thus, this
cheaper and more direct route to the natural pheromone
isomer, with high chemical and isomeric purity confer-
ring a high biological activity, provides the potential
basis for a commercial pheromone lure production.
Acknowledgement
(bis(tricyclohexylphosphine)benzylidene
ruthenium(IV)
chloride) (40 mg, 5 mol%) in CH2Cl2 (10 ml) via a
cannula. All apparatus was flame-dried under N2. The
mixture was heated to reflux for 1 h, cooled, concentrated
in vacuo and filtered through a pad of neutral alumina to
yield the product (230 mg, 70% over two steps). Without
further purification, the product (220 mg, 0.75 mmol) was
dissolved in dry THF (20 ml), treated with TBAF
J. Galman, UCL, is thanked for the optical rotation
data. Rothamsted Research receives grant-aided sup-
port from the Biotechnology and Biological Sciences
Research Council (BBSRC).
˚
(7.5 mmol, 1 M, 7.5 ml), microwave-dried 4 A molecular
References and notes
sieves (8 g) and refluxed overnight. The mixture was
filtered through Celite and purified by flash column
chromatography (Et2O) to yield (2S,7S)-1,4-nonadien-
2,7-diol (90 mg, 78%). Dienediol (45 mg, 0.29 mmol) was
dissolved in anhydrous MeOH (5 ml) and treated with a
1. Oakley, J. N.; Talbot, G.; Dyer, C.; Self, M. M.; Freer, J.
B. S.; Angus, W. J.; Barret, J. M.; Feuerhelm, G.; Snape,
J.; Sayers, L.; Bruce, T. J. A.; Smart, L. E.; Wadhams, L.
J. Integrated control of wheat blossom midge: variety