S. Mondal et al. / Tetrahedron Letters 50 (2009) 5277–5279
5279
(CH2), 112.5 (CH2), 136.8 (C), 144.7 (C), 144.9 (CH), 147.4 (C), 201.4 (CO), 212.0
(CO); HRMS (ESI) calcd for C20H28O2Na (M+Na)+, 323.1987; found 323.1988.
m); 13C NMR (75 MHz, CDCl3): d 14.1 (CH3), 14.2 (CH3), 18.6 (CH3), 19.1 (CH3),
30.0 (CH2), 30.5 (CH2), 31.5 (CH2), 31.6 (CH2), 36.2 (CH2), 36.4 (CH2), 42.4 (CH),
42.5 (CH), 43.6 (CH), 44.2 (CH), 44.4 (CH), 44.7 (CH), 46.7(CH), 46.8 (CH), 49.0
(CH2), 50.0 (CH2), 51.4 (CH), 51.6 (CH), 54.7 (CH), 55.6 (CH), 74.2 (OCH), 74.9
(OCH), 113.0 (CH2), 113.3 (CH2), 130.8 (CH), 133.4 (CH), 136.8 (CH), 138.7 (CH),
145.3 (C), 145.4 (C), 217.2 (CO), 217.5 (CO); HRMS (ESI) calcd for C18H26O2Na
(M+Na)+, 297.1830; found 297.1830. Compound 14 (for both diastereomers): IR
Compound 11: IR (neat): 1698, 3526 cmÀ1 1H NMR (300 MHz, CDCl3): d 0.97
;
(3H, d, J = 6.2 Hz), 1.31–1.45 (1H, m), 1.72 (3H, s), 1.79–1.82 (2H, m), 2.08 (1H,
dd, J = 2.3, 11.3 Hz), 2.41–2.50 (2H, m), 2.70–2.80 (1H, m), 3.36 (1H, J = 11.2 Hz),
4.0 (1H, m), 4.89 (2H, d, J = 6.4 Hz), 5.07 (1H, d, J = 10.5 Hz), 5.17 (1H, d,
J = 17.2 Hz), 6.03 (1H, ddd, J = 6.1, 10.5, 17.0 Hz); 13C NMR (75 MHz, CDCl3): d
14.0 (CH3), 18.6 (CH3), 31.2 (CH2), 35.7 (CH2), 46.3 (CH), 50.8 (CH), 57.4 (CH),
71.2 (OCH), 113.4 (CH2), 114.3 (CH2), 140.8 (CH), 145.3 (C), 215.8 (CO); HRMS
(ESI) calcd for C13H20O2Na (M+Na)+, 231.1361; found 231.1364. Compound 12
(neat): 1703, 3473 cmÀ1 1H NMR (300 MHz, CDCl3):d 0.97 (3H, d, J = 6.3 Hz),
;
1.27–1.39 (2H, m), 1.50–1.61 (1H, m), 1.66 (3H, s), 1.75–1.78 (2H, m), 2.03–2.18
(3H, m), 2.33–2.58 (4H, m) 2.62–2.73 (1H, m), 2.89–3.02 (2H, m), 3.26–3.41 (1H,
m), 4.82–5.02 (6H, m), 5.70–5.85 (2H, m); 13C NMR (75 MHz, CDCl3): d 14.1
(CH3), 18.7 (CH3), 19.4 (CH3), 31.3 (CH2), 31.5 (CH2), 35.7 (CH2), 36.0 (CH2), 36.5
(CH2), 36.6 (CH2), 37.4 (CH2), 39.9 (CH), 41.8 (CH2) 42.6 (CH), 44.4 (CH), 45.4
(CH), 46.6 (CH), 46.7 (CH), 48.3 (CH), 48.6(CH), 51.2 (CH), 51.9 (CH), 54.7 (CH),
55.1 (CH), 70.7 (OCH), 71.7 (OCH), 112.4 (CH2), 112.6 (CH2), 113.2 (CH2), 113.4
(CH2), 114.5 (CH2), 139.8 (CH), 140.6 (CH), 143.5 (CH), 143.7 (CH), 144.9 (C),
145.3 (C), 216.7 (CO), 217.6 (CO); HRMS (ESI) calcd for C20H30O2Na (M+Na)+,
(as 3:1 mixture of keto-enol tautomers): IR (neat): 1651, 1714, 3458 cmÀ1 1H
;
NMR (300 MHz, CDCl3) (for the diketone 12 from the mixture): d 1.01 (3H, d,
J = 7.7 Hz), 1.48 (1H, dt, J = 3.3, 13.0 Hz), 1.70 (3H, s), 1.73–1.75 (1H, m), 1.95
(1H, q, J = 3.3 Hz), 2.07–2.12 (1H, m), 2.40–2.50 (1H, m), 2.88 (1H, dt, J = 3.6,
12.3 Hz), 3.81 (1H, d, J = 12.3 Hz), 4.66 (1H, br s), 4.72 (1H, br s), 5.71 (1H, d,
J = 10.6 Hz), 6.14 (1H, d, J = 17.6 Hz), 6.40 (1H, dd, J = 10.5, 18.0 Hz); 13C NMR
(75 MHz, CDCl3) (for the diketone 12 from the mixture): d 14.3 (CH3), 20.4 (CH3),
31.0 (CH2), 34.7 (CH2), 45.6 (CH), 49.3 (CH), 64.1 (CH), 111.6 (CH2), 127.8 (CH2),
136.0 (CH), 145.8 (C), 197.4 (CO), 209.5 (CO). Enol form of 12 in the mixture: 1H
NMR (300 MHz, CDCl3): d 1.21 (3H, d, J = 7.3 Hz), 1.63–1.67 (1H, m), 1.77 (3H, s),
1.80–1.83 (1H, m), 2.0 (1H, q, J = 3.3 Hz), 2.13–2.17 (1H, m), 2.44 (1H, m), 3.21
(1H, m), 4.57 (1H, br s), 4.89 (1H, br s), 5.64 (1H, dd, J = 2.2, 10.1 Hz), 6.31 (1H,
dd, J = 2.2, 17.6 Hz), 6.44 (1H, m), 17.0 (1H, s); 13C NMR (75 MHz, CDCl3): d 18.7
(CH3), 21.8 (CH3), 23.0 (CH2), 24.9 (CH2), 36.2 (CH), 41.0 (CH), 114.0 (CH2), 127.0
(CH2), 130.6 (CH), 148.1 (C), 195.2 (CO); HRMS (ESI) calcd for C13H18O2Na
(M+Na)+, 229.1205; found 229.1209. Compound 13 (for both diastereomers): IR
325.2144; found 325.2144. Compound 16: IR (neat): 1693, 3533 cmÀ1 1H NMR
;
(300 MHz, CDCl3): d 0.98 (3H, d, J = 6.3 Hz), 1.21–1.38 (2H, m), 1.64–1.70 (1H,
m), 1.77 (3H, br s), 1.83–1.88 (2H, m), 2.09–2.15 (3H, m), 2.36–2.47 (3H, m),
2.58–2.82 (3H, m), 2.92–2.97 (1H, m), 4.25–4.27 (1H, m), 4.71 (1H, br s), 4.80
(1H, Br s), 5.17–5.22 (1H, m), 5.41 (1H, br s); 13C NMR (75 MHz, CDCl3) (for the
major diastereomer): d 14.5 (CH3), 19.5 (CH3), 28.9 (CH2), 32.0 (CH2), 35.5 (CH2),
36.9 (CH2), 37.7 (CH), 38.0 (CH), 41.5 (CH), 42.0 (CH), 45.3 (CH), 59.6 (CH), 71.8
(OCH), 104.6 (CH2), 113.9 (CH), 131.1 (CH), 151.1 (C), 211.5 (CO); HRMS (ESI)
calcd for C18H26O2Na (M+Na)+, 297.1830; found 297.1834.
(neat): 1693, 3535 cmÀ1
;
1H NMR (300 MHz, CDCl3): d 0.26–0.31 (1H, m), 0.98
7. Furukawa, J.; Kobuke, Y.; Fueno, T. J. Am. Chem. Soc. 1970, 92, 6548.
8. Srikrishna, A.; Vijaykumar, D.; Reddy, T. J. Tetrahedron 1997, 53, 1439.
9. (a) Corey, E. J.; Palani, A. Tetrahedron Lett. 1997, 14, 2397; (b) Kawatsura, M.;
Kishi, E.; Kito, M.; Sakai, T.; Shirahama, H.; Matsuda, F. Synlett 1997, 479.
(3H, d, J = 6.3 Hz), 1.14–1.23 (2H, m), 1.34–1.44 (2H, m), 1.60 (3H, s), 1.73–1.82
(3H, m), 2.02–2.11 (1H, m), 2.29 (1H, d, J = 12.1 Hz) 2.36–2.56 (2H, m), 2.65–2.76
(2H, m), 3.08 (1H, br s), 3.27 (1H, d, J = 12.0), 4.78–4.85 (2H, m), 5.98–6.08 (2H,