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16. Spectral data of compound 1: Low melting solid, 1H NMR
(300 MHz, CDCl3): d 4.24 (dd, 1H, J = 10.4, 2.4 Hz), 3.90
(dd, 1H, J = 13.6, 2.4 Hz), 2.51 (m, 1H), 2.46–2.22 (m,
5H), 2.19 (m, 1H), 1.71 (s, 3H), 1.69 (s, 3H), 1.19 (d, 3H,
J = 7.5 Hz), 1.18 (t, 3H, J = 8.0 Hz), 1.11 (d, 3H,
J = 8.0 Hz), 1.07 (t, 3H, J = 7.2 Hz), 1.02 (d, 3H, J =
7.2 Hz); 13C NMR (50 MHz, CDCl3): d 197.0, 194.3,
173.5, 172.3, 108.4, 107.5, 83.2, 81.6, 80.8, 40.2, 39.8, 34.5,
25.3, 10.8, 10.7, 9.6, 9.4, 9.2, 9.1, 9.0; IR (Neat): 1721,
1662, 1615 cmꢀ1
;
FAB Mass: m/z 335 [M+H]+,
25
½aꢁD +23.6 (c 0.38, CHCl3); Spectral data of compound 2:
liquid, 1H NMR (300 MHz, CDCl3): d 4.22 (dd, 1H,
J = 8.6, 4.3 Hz), 4.13 (dd, 1H, J = 12.16, 1.43 Hz), 2.48
(m, 1H), 2.42–2.34 (m, 5H), 2.18 (m, 1H), 1.75 (s, 3H),
1.71 (s, 3H), 1.25 (d, 3H, J = 7.2 Hz), 1.16 (t, 3H,
J = 7.8 Hz), 1.13 (t, 3H, J = 7.2 Hz), 1.01 (d, 3H,
J = 7.2 Hz), 1.00 (d, 3H, J = 7.2 Hz); 13C NMR (75
MHz, CDCl3): d 195.2, 194.8, 172.6, 170.4, 108.2, 107.5,
84.3, 82.5, 80.8, 40.7, 40.0, 34.0, 25.4, 15.4, 10.9, 10.7, 9.5,
9.2, 9.1, 8.8; IR (Neat) : 1739, 1658, 1615 cmꢀ1; FAB
Mass: m/z 335 [M+H]+, HRMS calcd for C20H30O4:
11. Horita, K.; Yoshioka, T.; Tanaka, T.; Oikawa, Y.;
Yonemitsu, O. Tetrahedron 1986, 42, 3021–3028.
12. Dess, D. B.; Martin, J. C. J. Am. Chem. Soc. 1991, 113,
7277–7287.
25
335.2222. Found: 335.2251. ½aꢁD +110.6 (c 1.81, CHCl3).