322
G. Mehta, P. Maity / Tetrahedron Letters 49 (2008) 318–322
101, 12030–12035; (d) Batova, A.; Lam, T.; Wascholow-
HRMS(ES) m/z calcd for C21H29O4(M+H+): 345.2066;
found: 345.2076. Compound 32: mp 87.2–87.9 °C; IR
ski, V.; Yu, A. L.; Giannis, A.; Theodorakis, E. A. Org.
Biomol. Chem. 2007, 5, 494–500, and references cited
therein.
1
(neat) 2966, 2925, 1732, 1455 cmꢀ1; H NMR (300 MHz,
CDCl3) d 6.21 (dd, J = 9.0, 6.6 Hz, 1H), 6.08 (dd, J = 8.4,
0.9 Hz, 1H), 4.81–4.61 (m, 1H), 3.39 (s, 3H), 3.04 (t,
J = 6.3 Hz, 1H), 2.64–2.49 (m, 2H), 2.39 (d, J = 9.6 Hz,
1H), 2.20 (dd, J = 13.5, 4.5 Hz, 1H), 1.59 (s, 3H), 1.55 (s,
3H), 1.45 (s, 3H), 1.31 (dd, J = 13.2, 9.6 Hz, 1H), 1.20 (s,
3H); 13C NMR (75 MHz, CDCl3) d 205.4, 133.2, 132.4,
128.6, 118.9, 88.4, 85.8, 82.2, 51.2, 45.2, 42.5, 29.7, 28.7,
28.0, 27.7, 25.8, 17.6; HRMS(ES) m/z calcd for
C17H24O3Na (M+Na+): 299.1623; found: 299.1628. Com-
5. Li, N.-G.; Wang, J.-X.; Liu, X.-R.; Lin, C.-J.; You, Q.-D.;
Guo, Q.-L. Tetrahedron Lett. 2007, 48, 6586–6589.
6. (a) Bichan, J.; Yates, P. Can. J. Chem. 1975, 53, 2054; (b)
Yates, P.; Auksi, H. Can. J. Chem. 1979, 57, 2853–2862.
7. Wessely, F.; Sinwel, F. Monatsh. Chem. 1950, 81, 1055–
1059.
8. Tisdale, E. J.; Chowdhury, C.; Vong, B. G.; Li, H.;
Theodorakis, E. A. Org. Lett. 2002, 4, 909–912.
9. Wessely oxidations are recognized to proceed via an
electrophilic mechanism10 and electron-donating o-sub-
stituents facilitate and direct the process. In order to
regiochemically steer the oxidation to place the prenyl
group in the requisite position, it is important that the o0-
position is not occupied by a better electron-donating
substituent. All the substrates (except 22) studied by us
conform to this reasoning and hence the successful
placement of the prenyl group on the tricyclic scaffold.
10. Bubb, W. A.; Sternhell, S. Tetrahedron Lett. 1970, 11,
4499–4502.
pound 34: IR (neat) 2933, 1789, 1454, 1434 cmꢀ1 1H
;
NMR (300 MHz, CDCl3) d 5.94–5.89 (m, 1H), 5.80–5.74
(m, 1H), 5.27–5.23 (m, 1H), 3.42 (s, 3H), 3.23 (t,
J = 3.0 Hz, 1H), 2.68–2.46 (m, 4H), 1.73 (s, 3H), 1.65 (s,
4H); 13C NMR (75 MHz, CDCl3) d 178.0, 134.9, 128.8,
121.5, 118.6, 76.1, 64.8, 56.2, 42.8, 27.8, 27.5, 25.7, 25.5,
17.9; HRMS(ES) m/z calcd for C14H18O3Na (M+Na+):
257.1154; found: 257.1146. Compound 37: mp 142.3–
143.2 °C; IR (neat) 2917, 1787, 1729, 1454 cmꢀ1; 1H NMR
(300 MHz, CDCl3) d 5.15 (t, J = 7.8 Hz, 1H), 3.57 (dd,
J = 13.5, 6.3 Hz, 1H), 3.53 (s, 3H), 2.82–2.68 (m, 2H),
2.61–2.47 (m, 2H), 2.21 (dd, J = 9.3, 6.0 Hz, 1H), 2.11 (dd,
J = 9.6, 5.1 Hz, 1H), 1.69 (s, 3H), 1.61 (br s, 4H); 13C
NMR (75 MHz, CDCl3) d 207.1, 174.9, 136.8, 114.8, 95.9,
93.6, 52.6, 51.0, 36.2, 31.6, 29.6, 29.3, 28.9, 26.0, 17.8;
HRMS(ES) m/z calcd for C15H18O4Na (M+Na+):
285.1103; found: 285.1099.
11. All new compounds reported here were racemic and
characterized on the basis of spectroscopic data (IR, 1H
and 13C NMR and mass). Spectral data for some of the
key compounds follows: Compound 9: IR (neat) 2935,
1789, 1737, 1442 cmꢀ1 1H NMR (300 MHz, CDCl3) d
;
6.09–6.06 (m, 1H), 4.90 (t, J = 7.5 Hz, 1H), 3.37–3.27 (m,
2H), 2.80–2.67 (m, 2H), 2.37–2.24 (m, 2H), 1.87 (d,
J = 1.8 Hz, 3H), 1.82 (dd, J = 3.3, 1.8 Hz, 1H), 1.72 (s,
3H), 1.64 (s, 3H); 13C NMR (75 MHz, CDCl3) d 200.8,
177.7, 138.7, 136.3, 125.2, 115.9, 82.5, 48.9, 46.5, 38.1,
30.7, 28.5, 25.9, 21.1, 18.0; HRMS(ES) m/z calcd for
C15H18O3Na (M+Na+): 269.1154; found: 269.1141. Com-
pound 18: mp 118.8–119.2 °C; IR (neat) 2927, 1792, 1742,
12. X-ray data was collected at 291 K on a SMART CCD–
BRUKER diffractometer with graphite monochromated
˚
MoKa radiation (k = 0.7107 A). The crystal structure was
solved by direct methods (SIR92) and refined by full-
matrix least-squares method on F2 using SHELXL-97.
Crystallographic data have been deposited with the Cam-
bridge Crystallographic Data Centre and assigned the
corresponding CCDC numbers. Compound 18: C15H18O4,
MW = 262.29, crystal system: monoclinic, space group:
1
1621 cmꢀ1; H NMR (300 MHz, CDCl3) d 6.30–6.25 (m,
2H), 4.67 (t, J = 6.9 Hz, 1H), 3.45 (s, 3H), 3.39–3.36 (m,
1H), 2.94 (d, J = 10.5 Hz, 1H), 2.82 (dd, J = 13.8, 7.2 Hz,
1H), 2.63 (dd, J = 13.5, 8.4 Hz, 1H), 2.27 (dd, J = 13.5,
3.3 Hz, 1H), 1.90–1.79 (m, 1H), 1.61 (s, 6H); 13C NMR
(75 MHz, CDCl3) d 197.6, 176.4, 135.7, 130.9, 128.0,
116.4, 86.2, 85.2, 52.1, 46.1, 40.5, 29.6, 26.0, 25.9, 17.7;
HRMS(ES) m/z calcd for C15H18O4Na (M+Na+):
285.1103; found: 285.1100. Compound 21: mp 155.1–
155.5 °C; IR (neat) 2940, 1790, 1737, 1638 cmꢀ1; 1H NMR
(300 MHz, CDCl3) d 4.81–4.75 (m, 2H), 3.57 (s, 3H), 3.44
(s, 3H), 3.24 (d, J = 1.8 Hz, 1H), 2.95 (d, J = 10.5 Hz,
1H), 2.81 (dd, J = 13.8, 7.5 Hz, 1H), 2.64 (dd, J = 13.5,
8.4 Hz, 1H), 2.23 (dd, J = 13.8, 3.9 Hz, 1H), 2.04–1.96 (m,
1H), 1.62 (s, 6H); 13C NMR (75 MHz, CDCl3) d 196.6,
176.4, 155.2, 135.0, 116.7, 93.2, 86.8, 85.2, 55.5, 51.8, 50.2,
41.4, 29.2, 25.9 (2C), 17.6; HRMS(ES) m/z calcd for
C16H20O5Na (M+Na+): 315.1208; found: 315.1204. Com-
˚
˚
P21/c, cell parameters: a = 11.869(2) A, b = 7.7303(15) A,
3
˚
˚
c = 15.387(3) A, b = 103.623(3)°, V = 1372.1(5) A , Z = 4,
q
calc = 1.270 g cmꢀ3 F(000) = 560, l = 0.091 mmꢀ1
,
,
number of l.s. parameters = 175, R1 = 0.0428 for 2144
reflections with I > 2r(I) and 0.0511 for all 2542 data.
wR2 = 0.1077, GOF = 1.047 for all data, CCDC-658802.
Compound 21: C16H20O5, MW = 292.32, crystal system:
monoclinic, space group: P21/c, cell parameters:
˚
˚
˚
a = 7.6309(16) A, b = 25.436(5) A, c = 7.8003(17) A, b =
95.493(4)°, V = 1507.1(6) A , Z = 4, qcalc = 1.288 g cmꢀ3
,
3
˚
F(000) = 624, l = 0.095 mmꢀ1, number of l.s. parame-
ters = 194, R1 = 0.0462 for 2331 reflections with I > 2r(I)
and 0.0564 for all 2790 data. wR2 = 0.1136, GOF = 1.058
for all data, CCDC-661601. Compound 37: C15H18O4,
MW = 262.29, crystal system: monoclinic, space group:
˚
˚
P21/c, cell parameters: a = 15.504(3) A, b = 7.8487(14) A,
pound 29: IR (neat) 2935, 1791, 1733, 1656 cmꢀ1
;
1H
c = 11.296(2) A, b = 97.791(3)°, V = 1361.9(4) A , Z = 4,
3
˚
˚
NMR (300 MHz, CDCl3) d 5.01–4.95 (m, 2H), 3.56 (s,
3H), 2.97 (d, J = 5.1 Hz, 1H), 3.06 (dd, J = 15.0, 6.6 Hz,
1H), 2.78–2.61 (m, 3H), 2.33 (dd, J = 15.3, 7.2 Hz, 1H),
1.98 (d, J = 6.6 Hz, 2H), 1.71 (s, 6H), 1.65 (s, 6H), 1.29 (s,
3H); 13C NMR (75 MHz, CDCl3) d 201.0, 177.7, 152.8,
136.1, 134.9, 120.8, 119.4, 115.9, 83.1, 61.8, 51.9, 45.8,
39.9, 39.3, 28.6, 27.5, 25.9, 25.7, 18.1, 17.7, 12.6;
q
calc = 1.279 g cmꢀ3 F(000) = 560, l = 0.092 mmꢀ1
,
,
number of l.s. parameters = 175, R1 = 0.0457 for 2021
reflections with I > 2r(I) and 0.062 for all 2492 data.
wR2 = 0.1334, GOF = 1.048 for all data, CCDC-661603.
13. For a recent review on the photochemistry of b,c-
unsaturated carbonyl compounds, see: Zimmerman, H.
E.; Armesto, D. Chem. Rev. 1996, 96, 3065–3112.