LETTER
Oxidative Dehydrogenation and the Aromatization of Polycycles
2045
(11) Typical Experimental Procedure: To a solution of IBX
(0.2–0.4 mmol) in DMSO (10 mL) was added Diels–Alder
adduct (0.1 mmol) and the mixture was stirred at 80–85 °C
for 10–24 h, until the starting material disappeared. At the
conclusion of the reaction (TLC monitoring), the reaction
mixture was quenched with H2O. The insoluble
CDCl3): d = 1.98 (s, 6 H), 2.20–2.30 (m, 2 H), 4.08–4.09 (m,
2 H), 6.83 (dd, J1 = J2 = 1.8 Hz, 2 H). 13C NMR (75 MHz,
CDCl3): d = 12.3, 48.6, 73.5, 139.6, 142.6, 160.2, 184.3. MS:
m/z = 201 [M + H+]. Compound 11: 1H NMR (400 MHz,
CDCl3): d = 2.17 (s, 3 H), 2.33–2.38 (m, 2 H), 4.14–4.16 (m,
2 H), 6.49 (s, 1 H), 6.91 (dd, J1 = J2 = 2.0 Hz, 2 H), 7.06–
7.09 (m, 1 H), 7.20–7.33 (m, 3 H). 13C NMR (100 MHz,
CDCl3): d = 20.4, 48.4, 48.7, 73.8, 125.6, 129.1, 129.4,
130.3, 133.5, 133.8, 136.2, 142.5, 142.7, 147.7, 160.6,
160.8, 182.9, 184.3. MS: m/z = 263 [M + H+]. Compound 12:
1H NMR (300 MHz, CDCl3): d = 2.29–2.39 (m, 8 H), 4.21–
4.23 (m, 2 H), 6.89 (dd, J1 = J2 = 1.8 Hz, 2 H), 7.79 (s, 2
H).13C NMR (75 MHz, CDCl3): d = 182.0, 162.8, 142.8,
142.6, 130.8, 127.4, 73.3, 48.7, 20.1. Compound 17: mp
117 °C. Lit mp 117–119 °C.13 Compound 18: 1H NMR (300
MHz, CDCl3): d = 2.15 (s, 6 H), 2.38 (s, 6 H), 7.81 (s, 2 H).
13C NMR (75 MHz, CDCl3): d = 183.5, 143.2, 143.1, 130.2,
127.4, 20.2, 12.9. Compound 19: mp 209 °C. Lit mp 209–
210 °C.14 Compound 20: 1H NMR (400 MHz, CDCl3): d =
2.44 (s, 6 H), 4.65 (dt, J1 = 5.2 Hz, J2 = 1.6 Hz, 4 H), 5.30
(d, J = 10.4 Hz, 2 H), 5.52 (d, J = 17.2 Hz, 2 H), 6.13–6.23
(m, 2 H), 6.61 (s, 2 H), 7.99 (s, 2 H). 13C NMR (100 MHz,
CDCl3): d = 148.2, 135.6, 133.9, 125.4, 121.6, 117.2, 103.9,
69.4, 20.4.
iodosobenzoic acid (IBA) was filtered off with the aid of a
Celite® pad. The filtrate was extracted with Et2O (3 × 30 mL)
and the combined organic layers were washed with sat.
NaHCO3 solution and finally with brine. The organic layer
was dried over anhyd MgSO4 and removal of solvent gave
the crude compound which was purified by the column
chromatography (silica gel) using petroleum ether and
EtOAc to afford the pure dehydrogenated compound.
Selected spectral data: Compound 7: 1H NMR (300 MHz,
CDCl3): d = 2.31–2.34 (m, 2 H), 4.09–4.12 (m, 2 H), 6.57 (s,
2 H), 6.86 (dd, J1 = J2 = 1.8 Hz, 2 H). 13C NMR (100 MHz,
CDCl3): d = 48.5, 73.9, 135.8, 142.6, 160.8, 184.1. MS:
m/z = 172 [M+]. Compound 8: 1H NMR (300 MHz, CDCl3):
d = 2.30–2.40 (m, 2 H), 4.24–4.27 (m, 2 H), 6.90 (dd,
J1 = J2 = 1.8 Hz, 2 H), 7.69 (dd, J1 = 5.5 Hz, J2 = 3.3 Hz, 2
H), 8.07 (dd, J1 = 5.6 Hz, J2 = 3.3 Hz, 2 H). 13C NMR (75
MHz, CDCl3): d = 48.8, 73.4, 126.3, 132.9, 133.4, 142.6,
163.2, 181.8. MS: m/z = 223 [M + H+]. Compound 9:
1H NMR (400 MHz, CDCl3): d = 2.36–2.42 (m, 2 H), 4.30–
4.32 (m, 2 H), 6.94 (dd, J1 = J2 = 1.8 Hz, 2 H), 7.64–7.67 (m,
2 H), 8.02–8.05 (m, 2 H), 8.59 (s, 2 H). 13C NMR (100 MHz,
CDCl3): d = 48.8, 73.2, 128.4, 129.2, 129.8, 130.1, 134.6,
142.5, 164.6, 181.3. Compound 10: 1H NMR (300 MHz,
(12) Labahn, A.; Schmid, R.; Goebel, F.; Warnecke, A. J. Chem.
Soc., Perkin Trans. 2 1999, 1199.
(13) Skarzewski, J. Tetrahedron 1984, 40, 4997.
(14) Allen, C. F. H.; Bell, A. Org. Synth. Coll Vol. III 1955, 310.
Synlett 2004, No. 11, 2043–2045 © Thieme Stuttgart · New York