References and Notes
<A NAME="RG01706ST-1">1</A>
Davies-Coleman MT.
Rivett DE. In Progress in the Chemistry of Organic Natural Products
Vol. 55:
Herz W.
Grisebach H.
Kirb GW.
Tamm C.
Springer-Verlag;
New York:
1989.
p.1
<A NAME="RG01706ST-2">2</A> Review:
Blázquez MA.
Bermejo A.
Zafra-Polo MC.
Cortés D.
Phytochem. Anal.
1999,
10:
161
See, for instance:
<A NAME="RG01706ST-3A">3a</A>
Sam TW.
Yeu CS.
Matsjeh S.
Gan EK.
Razak D.
Mohamed AL.
Tetrahedron Lett.
1987,
28:
2541
<A NAME="RG01706ST-3B">3b</A>
Wu YC.
Duh CY.
Chang FR.
Wang SK.
Chang JJ.
McPhail AT.
Lee KH.
J. Nat. Prod.
1991,
54:
1077
Review:
<A NAME="RG01706ST-4A">4a</A>
Mereyala HB.
Joe M.
Curr. Med. Chem.: Anti-Cancer Agents
2001,
1:
293
<A NAME="RG01706ST-4B">4b</A> See also:
Inayat-Hussain SH.
Osman AB.
Din LB.
Taniguchi N.
Toxicol. Lett.
2002,
131:
153
<A NAME="RG01706ST-5">5</A> Review:
Zhao G.
Wu B.
Wu XY.
Zhang YZ.
Mini-Rev. Org. Chem.
2005,
2:
333
<A NAME="RG01706ST-6A">6a</A>
Kowarski CR.
Sarel S.
J. Org. Chem.
1973,
38:
117
<A NAME="RG01706ST-6B">6b</A> See also:
Baran A.
Kazaz C.
Secen H.
Sütbeyaz Y.
Tetrahedron
2003,
59:
3643
<A NAME="RG01706ST-7A">7a</A>
A mixture of vinylene carbonate (9.89 g, 115 mmol) and furane (1.60 g, 23 mmol) was
heated in a sealed tube protected from the light at 150 °C during 12 h. After this
time, the reaction crude was distilled in vacuo to give 8.80 g (102 mmol) of vinylene
carbonate and 610 mg (66%) of mixture of endo- and exo-cycloadducts in a ratio (endo:exo) of 3.5:1 (evaluated by 1H NMR).
<A NAME="RG01706ST-7B">7b</A>
To a solution of endo:exo cycloadduct mixture (610 mg, 3.96 mmol) in MeOH (39.6 mL), K2CO3 (819.7 mg, 5.94 mmol) was added. The mixture was stirred at r.t. for 24 h. After
this time the reaction crude was filtered through a pad of Celite® and the solvent was distilled in vacuo. After purification by column chromatography (silica gel, hexane-EtOAc, 1:1) 379 mg
(2.96 mmol) of 5a and 107 mg (0.08 mmol) of 5b were isolated (combined yield 5a + 5b, 486.8 mg, 3.8 mmol, 96%).
Compound 5a: 1H NMR (200 MHz, CDCl3): δ = 6.50 (d, 2 H, J = 0.9 Hz), 4.93 (dt, 2 H, J = 0.9, 2.2 Hz), 4.20 (m, 2 H), 2.30 (s, 1 H), 2.74 (s, 1 H) ppm. 13C NMR (200 MHz, CDCl3): δ = 134.9, 80.31, 67.15 ppm. R
f
= 0.24. Anal. Calcd for C6H8O3: C, 56.24; H, 6.29. Found: C, 56.08; H, 6.35.
<A NAME="RG01706ST-8">8</A> For a comprehensive review on enantioselective enzymatic desymmetrizations in
organic synthesis, see:
Garcia-Urdiales E.
Alfonso I.
Gotor V.
Chem. Rev.
2005,
105:
313
<A NAME="RG01706ST-9A">9a</A>
To a solution of 100 mg (0.78 mmol) of 5a in vinylacetate (10 mL), 837 mg of CCL (Fluka) were added. The reaction mixture was
stirred 5 h at r.t. After this time the reaction crude was filtered through a pad
of Celite® and purified by column chromatography (silica gel, hexane-EtOAc, 7:3) giving 110
mg (0.65 mmol, 83%) of compound 4 as a colorless oil.
Compound 4: 1H NMR (200 MHz, CDCl3): δ = 6.56 (dd, 1 H, J = 1.4, 5.6 Hz), 6.49 (dd, 1 H, J = 1.4, 5.6 Hz), 5.05 (dd, 1 H, J = 1.4, 3.8 Hz), 4.95 (m, 2 H), 4.40 (dd, 1 H, J = 4.4, 7.2 Hz), 2.06 (s, 3 H) ppm. 13C NMR (200 MHz, CDCl3): δ = 170.43, 135,21, 135.02, 80.29, 78.77, 69.91, 67.86, 29.67, 20,69 ppm. R
f
= 0.22; [α]D
24 -1.07 (c 0.93, CHCl3). Anal. Calcd for C8H10O4: C, 56.47; H, 5.92. Found: C, 56.25; H, 6.12.
The ee was determined by 19F NMR spectroscopy of the Mosher’s ester derivative of 4. See ref. 9b.
Compound 4: 19F NMR (250 MHz, CDCl3): δ = -72.02 (major), -72.31 (minor) ppm; ee 92%.
<A NAME="RG01706ST-9B">9b</A>
Dale JA.
Mosher HS.
J. Am. Chem. Soc.
1973,
95:
512
<A NAME="RG01706ST-10">10</A>
Compound 3: 1H NMR (300 MHz, CDCl3): δ = 6.49 (s, 2 H), 6.36 (dd, 1 H, J = 17.1, 1.5 Hz), 6.05 (dd, 1 H, J = 17.1, 10.5 Hz), 5.85 (dd, 1 H, J = 10.5, 1.5 Hz), 5.21 (m, 2 H), 5.13 (m, 2 H), 1.90 (s, 3 H) ppm. 13C NMR (300 MHz, CDCl3): δ = 169.91, 165.04, 134.80, 134.71, 131.41, 127.50, 78.75, 78.67, 68.72, 68.67,
20.38 ppm. Anal. Calcd for C11H12O5: C, 58.93; H, 5.39. Found: C, 57.89; H, 5.17. [α]D
24 -2.0 (c 1.1, CHCl3).
For a review on the metathesis tandem reactions in oxa- and azanorbornene derivatives,
see:
<A NAME="RG01706ST-11A">11a</A>
Arjona O.
Csákӱ AG.
Plumet J.
Eur. J. Org. Chem.
2002,
611
<A NAME="RG01706ST-11B">11b</A> For a recent application, see:
Maechling S.
Norman SE.
McKendrick JE.
Basra S.
Köppner K.
Blechert S.
Tetrahedron Lett.
2006,
47:
189
For a comprehensive review on synthetic applications of oxanorbornene derivatives,
see:
<A NAME="RG01706ST-12A">12a</A>
Vogel P.
Cossy J.
Plumet J.
Arjona O.
Tetrahedron
1999,
55:
13521
<A NAME="RG01706ST-12B">12b</A>
Vogel P.
Curr. Org. Chem.
2000,
65:
455
<A NAME="RG01706ST-12C">12c</A>
Robina I.
Vogel P.
Synthesis
2005,
675
<A NAME="RG01706ST-12D">12d</A>
Vogel P. In
The Organic Chemistry of Sugars
Levy DE.
Fugedi P.
Taylor and Francis Group CRC;
Boca Raton:
2006.
Chap. 13.
p.629-725
<A NAME="RG01706ST-13">13</A>
Commercially available Hoveyda-Grubbs catalyst 2nd generation shows efficiencies
similar to Grubb’s catalyst 2nd generation, but with different substrate selectivity.
Specifically, it catalyzes ring-closing, ring-opening, and cross-metathesis reactions
of electron-deficient substrates.
<A NAME="RG01706ST-14">14</A>
To a solution of 3 (23 mg, 0.1 mmol) in CH2Cl2 (2.2 mL) under Ar, was added Hoveyda-Grubbs catalyst (3.2 mg, 0.005 mmol, 5 mol%)
in CH2Cl2 (0.3 mL). After bubbling of a stream of ethylene, the reaction mixture was stirred
for 24 h at r.t. The solvent was removed in vacuo providing compound 2 (21 mg, 0.090 mmol, 90%).
Compound 2: 1H NMR (300 MHz, CDCl3): δ = 6.43 (dd, 1 H, J = 1.5, 17.4 Hz), 6.13 (dd, 1 H, J = 10.5, 17.4 Hz), 5.90 (m, 1 H), 5.50 (m, 2 H), 5.36 (dm, 1 H, J = 17.2 Hz), 5.26 (dm, 1 H, J = 10.26), 4.58 (m, 2 H), 2.05 (s, 3 H) ppm.
13C NMR (300 MHz, CDCl3): δ = 170.33, 165.05, 132.95, 132.37, 127.97, 119.76, 80.21, 74.02, 20.38 ppm. Anal.
Calcd for C11H12O5: C, 58.93; H, 5.39; found: C, 58.84; H, 5.44. [α]D
24 -2.8 (c 0.7, CHCl3).
