References
1a
Buta JG.
Flippen JL.
Lusby WR.
J.
Org. Chem.
1978,
49:
1002
1b
Sun N.
Xue Z.
Liang X.
Huang L.
Acta Pharm. Sin.
1979,
14:
39
1c
Du J.
Nie CM.-H.
Nie RL.
J.
Nat. Prod.
1999,
62:
1664
2
Kang S.
Cai S.
Teng L.
Acta Pharm.
Sin.
1981,
16:
867
3a
Frey B.
Wells A.
Rogers DH.
Mander LN.
J.
Am. Chem. Soc.
1998,
120:
1914
3b
Rogers DH.
Frey B.
Roden FR.
Russkamp F.-W.
Willis AC.
Mander LN.
Aust.
J. Chem.
1999,
52:
1093
3c
Frey B.
Wells AP.
Roden R.
Au TD.
Hockless DC.
Willis AC.
Mander LN.
Aust. J. Chem.
2000,
53:
819
4
Ye T.
McKervey MA.
Chem. Rev.
1994,
94:
1091
5
Zhang H.
Appels DC.
Hockless DCR.
Mander LN.
Tetrahedron
Lett.
1998,
39:
6577
6
Afarinkia K.
Vinader V.
Nelson TD.
Posner GH.
Tetrahedron
1992,
42:
9111
7 The indenone 5 (R1 = H)
(550 mg, 3.44 mmol) and the pyrone 6 (R2 = H)
(504 mg, 3.27 mmol) were dissolved in CH2Cl2 (1
mL). The reaction mixture was then subjected to high pressure (19
kbar) for 24 h. The solvent was removed under reduced pressure and
the residue was chromato-graphed on silica gel (petroleum ether
40-60 °C:EtOAc =
3
: 1) to yield the cycloadduct 7 (R = H)
(736 mg, 72%, based on pyrone). Recrystallization from
EtOAc afforded colourless crystals. Mp 131-133 °C.
IR: νmax (CHCl3): 1763 (s), 1740
(s), 1705 (s), 1597 (s), 1491 (w), 1458 (w), 1439 (w), 1350 (w),
1308 (m), 1284 (m), 1256 (s), 1196 (w), 1169 (w), 1127 (w), 1109
(w), 1092 (m), 1077 (m), 1069 (m), 1024 (w), 981 (w), 962 (w), 740
(w)cm-1. 1H NMR
(300 MHz, CDCl3): δ = 7.62 (1 H, d, J
8,7 = 8.6
Hz, H-8), 6.94 (1 H, dd, J
7,8 = 8.6
Hz, J
7,5 = 2.2
Hz, H-7), 6.51 (1 H, d, J
5,7 = 2.0
Hz, H-5), 6.36 (2 H, m, H-10, H-11), 5.45 (1 H, ddd, J
1,9a = 5.0
Hz, J
1,11 = 5.4
Hz, J
1,10 = 2.0
Hz, H-1), 4.32 (1 H, d, J
4a,9a = 7.1
Hz, H-4a), 4.03 (3 H, s, COOCH3), 3.85 (3 H, s, CH3O-C6),
3.63 (1 H, dd, J
9a,4a = 7.1
Hz, J
9a,1 = 5.0 Hz,
H-9a). 13C NMR (75 MHz, CDCl3): δ = 199.0
(C9), 169.5 (C3), 168.1 (C12), 166.1 (C6), 154.0 (C4b), 132.0 (C8a),
130.6 (C11), 129.8 (C10), 126.2 (C8), 117.1 (C5), 109.9 (C7), 74.9
(C1), 59.9 (C4), 56.1 (CH3O-C6), 53.7 (COOCH3),
52.8 (C9a), 39.50 (C4a). LRMS: m/z (%) = 314 (24) [M+],
268 (3), 242 (27), 226 (4), 211 (100), 168 (20), 160 (93), 139 (29),
134 (29), 123 (6), 106 (35), 91 (3), 77 (10), 63 (26). HRMS (EI):
Found 314.0787 [M+], C17H14O6 requires
314.0790. Anal. Calcd for C17H14O6:
C, 64.97%; H, 4.49%. Found: C, 64.51%;
H, 4.79%. The high-pressure reactor was purchased from
PSIKA Pressure Systems Ltd. This equipment consisted of an electrohydraulic
station controlling two hydraulic presses which pressed against
two pistons. The two pistons placed pressure on either side of a central
hollow chamber that contains the teflon reaction vessel suspended
in a castor oil mix (15% methanol/85% castor
oil). The ease with which traces of acid induce indenones to dimerize
and the thermal instability of α-pyrone adducts mandates
the use of high pressure to drive this kind of cycloaddition.
8
Ireland RE.
Anderson RC.
Badoud R.
Fitzsimmons BJ.
McGarvey GJ.
Thaisrivongs S.
Wilcox CS.
J. Am. Chem. Soc.
1983,
105:
1988
9a
Young WG.
Andrews LJ.
Lindenbaum SL.
Cristol SJ.
J. Am. Chem. Soc.
1944,
66:
811
9b
Fried J.
Elderfield RC.
J. Org. Chem.
1941,
6:
577
10 See: Lautens M.
Crudden CM.
Tetrahedron Lett.
1989,
36:
4803
11
Dess DB.
Martin JC.
J. Am. Chem. Soc.
1991,
113:
7277
12
Newman MS.
Landers JO.
J. Org. Chem.
1976,
42:
2556
13
Abdallah H.
Greé R.
Carrié R.
Can.
J. Chem.
1985,
63:
3031
14
Posner GH.
Hutchings RH.
Woodard BT.
Synlett
1997,
432
15
Alder K.
Schumacher M.
Wolff O.
Annalen
1949,
79:
564
16
Fleming I.
Frontier Orbitals and Organic Chemical Reactions
Wiley-Interscience;
Chicester:
1996.
17 FMO calculations were performed on
the Spartan (v5.01) program with the RHF/PM3 model.
