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MHz) δ (ppm) 171.0, 99.0, 69.3, 61.2, 60.5, 43.5, 32.9, 31.5, 28.3, 25.1, 22.4, 19.6, 14.1, 13.9. Anal.
24
calcd for C14H26O4: C, 65.09; H, 10.14. Found: C, 65.12; H, 10.18. Acetonide 15: [α]D +51.6 (c 0.6,
1
CHCl3). IR (film) 1732, 1464 cm−1. H NMR (CDCl3, 400 MHz) δ (ppm) 4.14 (ddq, J=10.7, 7.0, 2.9
Hz, 2H), 4.00 (dd, J=11.4, 10.4 Hz, 1H), 3.97–4.02 (m, 1H), 3.92 (dd, J=11.4, 5.4 Hz, 1H), 2.57 (dt,
J=10.3, 5.4 Hz, 1H), 1.48 (s, 3H), 1.39 (s, 3H), 1.26 (t, J=7.0 Hz, 3H), 1.22–1.52 (m, 8H), 0.88 (t, J=7.0
Hz, 3H). 13C NMR (CDCl3, 100 MHz) δ (ppm) 171.5, 98.4, 69.9, 61.4, 60.5, 46.9, 34.4, 31.6, 29.2, 24.4,
22.5, 19.2, 14.1, 13.9. Anal. calcd for C14H26O4: C, 65.09; H, 10.14. Found: C, 64.98; H, 10.09.
4.10. (4R,5R)-5-Formyl-2,2-dimethyl-4-pentyl-1,3-dioxane 3
To a cooled (−78°C) solution of ester 14 (129.1 mg, 0.5 mmol) in CH2Cl2 (5 mL) was added DIBAL
(0.6 mL, 0.6 mmol, 1 M in toluene) over a period of 30 min. The reaction mixture was stirred at
−78°C for 2 h, and then MeOH was added to quench the reaction. After 15 min water (1.0 mL) was
added; the resulting mixture was then allowed to warm to rt and stirred vigorously to form a precipitate.
After filtration of the precipitate, the mixture was diluted with ether and the phases were separated. The
organic phase was washed with water and brine, dried over MgSO4, and evaporated to a crude material.
Purification of the crude material by flash column chromatography (2.5% ethyl acetate/hexane) provided
aldehyde 3 (96.4 mg, 90%) as a colorless oil. [α]D24 −17.8 (c 1.4, CHCl3). IR (film) 1726 cm−1. 1H NMR
(CDCl3, 400 MHz) δ (ppm) 10.11 (d, J=4.1 Hz, 1H), 4.17 (dd, J=12.2, 2.9 Hz, 1H), 4.10 (dd, J=12.2,
1.5 Hz, 1H), 4.09–4.11 (m, 1H), 2.02–2.05 (m, 1H), 1.51 (s, 3H), 1.43 (s, 3H), 1.23–1.65 (m, 8H), 0.88
(t, J=6.8 Hz, 3H). 13C NMR (CDCl3, 100 MHz) δ (ppm) 204.8, 99.2, 70.1, 61.3, 49.6, 33.1, 31.4, 29.3,
24.8, 22.4, 18.6, 13.9. Anal. calcd for C12H22O3: C, 67.26; H, 10.35. Found: C, 67.50; H, 10.38.
4.11. (4R,5S)-5-Formyl-2,2-dimethyl-4-pentyl-1,3-dioxane 16
According to the reduction procedure described above, the reaction of aldehyde 3 with ester 15 (93.0
mg, 0.35 mmol) and DIBAL (0.45 mL, 0.45 mmol, 1 M in toluene) in CH2Cl2 (5 mL) afforded aldehyde
16 (66 mg, 88%) as a colorless oil. [α]D24 +48.0 (c 0.5, CHCl3). IR (film) 1720 cm−1. 1H NMR (CDCl3,
400 MHz) δ (ppm) 9.75 (d, J=2.2 Hz, 1H), 3.98–4.04 (m, 1H), 3.97 (d, J=6.1 Hz, 1H), 3.96 (dd, J=3.1
Hz, 1H), 2.64–2.70 (m, 1H), 1.43 (s, 3H), 1.39 (s, 3H), 1.22–1.60 (m, 8H), 0.88 (t, J=7.0 Hz, 3H). 13
C
NMR (CDCl3, 100 MHz) δ (ppm) 201.4, 98.7, 68.3, 58.5, 53.7, 34.7, 31.5, 28.4, 24.5, 22.5, 19.7, 13.9.
Anal. calcd for C12H22O3: C, 67.26; H, 10.35. Found: C, 67.11; H, 10.30.
Acknowledgements
We thank the Ministry of Education, Science and Culture, Japan, for a Grant-in-Aid for Scientific
Research (Nos. 9554046 and 10640525).
References
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425.
3. Richardson, T. I.; Rychnovsky, S. D. J. Org. Chem. 1996, 61, 4219–4231. After our work was finished, we were informed
by Prof. S. Rychnovsky that the measured rotation, α, was negative in the original notebook in his laboratory but in the
calculation the sign of the rotation was inadvertently dropped.