References
For general accounts on MCPBA reactions, see:
<A NAME="RG16405ST-1A">1a</A>
Comprehensive Organic Synthesis
Vol. 7:
Trost BM.
Fleming I.
Pergamon Press;
Oxford:
1991.
p.357-372
<A NAME="RG16405ST-1B">1b</A>
Paquette L.
Encyclopedia of Reagents for Organic Synthesis
Vol. 2:
John Wiley and Sons;
New York:
1995.
p.1192-1198
<A NAME="RG16405ST-2">2</A>
Prilezhaev N.
Ber.
1909,
42:
4811
For the well-known ‘butterfly’ mechanism of epoxidation see:
<A NAME="RG16405ST-3A">3a</A>
Bartlett PA.
Rec. Chem. Prog.
1957,
18:
111
For some recent reports on the radical hypothesis see:
<A NAME="RG16405ST-3B">3b</A>
Yamabe S.
Kondou C.
Minato T.
J. Org. Chem.
1996,
61:
616
<A NAME="RG16405ST-3C">3c</A>
Okovytyy S.
Gorb L.
Leszczynski J.
Tetrahedron
2002,
58:
8751
<A NAME="RG16405ST-3D">3d</A>
Bach RD.
Glukhovtsev MN.
Gonzalez C.
J. Am. Chem. Soc.
1998,
120:
9902
<A NAME="RG16405ST-4A">4a</A>
Warrener RN.
Elsey GM.
Pitt IG.
Russell RA.
Aust. J. Chem.
1995,
48:
241
For the synthesis of α-haloepoxides see also:
<A NAME="RG16405ST-4B">4b</A>
Ono T.
Henderson P.
Tetrahedron Lett.
2002,
43:
7961
<A NAME="RG16405ST-4C">4c</A>
Taber DF.
Mitten JV.
J. Org. Chem.
2002,
67:
3847
<A NAME="RG16405ST-4D">4d</A>
Benayoud F.
Begue JP.
Bonnet-Delpon D.
Fischer-Durand N.
Sdassi H.
Synthesis
1993,
1083
<A NAME="RG16405ST-5">5</A>
Kocienski P.
J. Chem. Soc., Perkin Trans. 1
1983,
945
<A NAME="RG16405ST-6">6</A>
Nakayama J.
Kamiyama H.
Tetrahedron Lett.
1992,
49:
7539
<A NAME="RG16405ST-7A">7a</A>
Benfatti F.
Cardillo G.
Fabbroni S.
Gentilucci L.
Perciaccante R.
Piccinelli F.
Tolomelli A.
Synthesis
2005,
61
<A NAME="RG16405ST-7B">7b</A>
Cardillo G.
Fabbroni S.
Gentilucci L.
Perciaccante R.
Piccinelli F.
Tolomelli A.
Org. Lett.
2005,
4:
533
<A NAME="RG16405ST-7C">7c</A>
Cardillo G.
Fabbroni S.
Gentilucci L.
Perciaccante R.
Tolomelli A.
Adv. Synth. Catal.
2005,
6:
833
<A NAME="RG16405ST-7D">7d</A>
Benfatti F.
Cardillo G.
Fabbroni S.
Gentilucci L.
Perciaccante R.
Tolomelli A.
ARKIVOC
2005,
(vi):
136
<A NAME="RG16405ST-8">8</A>
Typical Experimental Procedure.
To a stirred solution of 1 (1 mmol) in the solvent of choice at r.t. (see Table
[1]
), MCPBA was added in one portion. The reaction was stirred overnight and then diluted
with H2O and CH2Cl2 (5 mL). The two phases were separated and the organic layer was dried over Na2SO4 and solvent was removed under reduced pressure. Compounds 2 and 3 were isolated by flash chromatography on silica gel (cyclo-hexane-ethyl acetate,
9:1 as eluent). The characterization of compound 3 is reported in ref. 7d. Commercially available MCPBA was used in the reactions. Purified
peracid (according to J. Am. Chem. Soc. 1987, 109, 2770) was less reactive in the epoxidation, due to the lack of acid impurities.
Compound 2a: first diastereomer: R
f
= 0.44 (9:1, cyclo-hexane-EtOAc). 1H NMR (300 MHz, CDCl3): δ = 1.02 (3 H, t, J = 7.6 Hz), 1.45-1.81 (2 H, m), 2.89 (1 H, dt, J = 1.8, 5.6 Hz), 3.45 (1 H, d, J = 1.8 Hz), 3.93 (1 H, d, J = 15.0 Hz), 4.59 (1 H, s), 4.97 (1 H, d, J = 15.0 Hz), 7.16-7.44 (10 H, m). 13C NMR (75 MHz, CDCl3): δ = 9.4 (CH3), 24.2 (CH2), 44.9 (CH2), 57.3 (CH), 58.9 (CH), 59.5 (CH), 68.8 (quat), 127.8 (CH), 127.9 (CH), 128.1 (CH),
128.4 (CH), 128.7 (CH), 128.9 (CH), 133.8 (quat), 134.0 (quat), 164.5 (CO). LC-ESI-MS
(t
R 15.2 min): m/z = 386/388 [M + 1], 408/410 [M + Na]. IR (film): 2962, 2928, 1775, 1494, 1454, 1392,
1351, 1147, 1072 cm-1. Second diastereomer: R
f
= 0.30 (9:1, cyclohexane-EtOAc). 1H NMR (300 MHz, CDCl3): δ = 1.05 (3 H, t, J = 7.2 Hz), 1.53-1.77 (2 H, m), 3.27 (1 H, d, J = 2.2 Hz), 3.57 (1 H, dt, J = 2.2, 5.6 Hz), 3.91 (1 H, d, J = 15.0 Hz), 4.78 (1 H, s), 4.99 (1 H, d, J = 15.0 Hz), 7.18-7.43 (10 H, m). 13C NMR (75 MHz, CDCl3): δ = 9.6 (CH3), 24.6 (CH2), 44.9 (CH2), 57.6 (CH), 58.7 (CH), 59.4 (CH), 68.4 (quat), 127.7 (CH), 127.9 (CH), 128.2 (CH),
128.4 (CH), 128.7 (CH), 129.0 (CH), 133.7 (quat), 133.9 (quat), 163.4 (CO). LC-ESI-MS
(t
R 14.5 min): m/z = 386/388 [M + 1], 408/410 [M + Na]. IR (film): 3073, 2959, 2930, 1771, 1654, 1455,
1395, 1355, 1157, 1077 cm-1.
<A NAME="RG16405ST-9A">9a</A>
Alcaide B.
Almendros P.
Curr. Med. Chem.
2004,
11:
1921
<A NAME="RG16405ST-9B">9b</A>
Deshmukh ARAS.
Bhawal BM.
Krishnaswamy D.
Govande Vidyesh V.
Shinkre Bidhan A.
Jayanthi A.
Curr. Med. Chem.
2004,
11:
1889
<A NAME="RG16405ST-9C">9c</A>
Singh GS.
Tetrahedron
2003,
59:
7631
<A NAME="RG16405ST-9D">9d</A>
Miller MJ.
Hsiao CN.
Huang NZ.
Kalish VJ.
Peterson K.
Rajendra G.
Recent Adv. Chem. β-Lactam Antibiot.
1989,
70:
273 ; special publication of the Royal Society of Chemistry, London
<A NAME="RG16405ST-9E">9e</A>
Ojima I.
Shimizu N.
Qiu Xiaogang C.
Hauh JC.
Nakahashi K.
Bull. Soc. Chim. Fr.
1987,
4:
649
<A NAME="RG16405ST-10A">10a</A>
Hayes BL.
Aldrichimica Acta
2004,
37:
66
<A NAME="RG16405ST-10B">10b</A>
Kappe CO.
Angew. Chem. Int. Ed.
2004,
43:
6250
<A NAME="RG16405ST-11A">11a</A>
Hanzlik RP.
Shearer GO.
J. Am. Chem. Soc.
1975,
97:
5231
<A NAME="RG16405ST-11B">11b</A>
Kropf H.
Yazdanbachsch MR.
Tetrahedron
1974,
30:
3455
<A NAME="RG16405ST-12">12</A>
Zhang HY.
Sun YM.
Wang XL.
J. Org. Chem.
2002,
67:
2709
<A NAME="RG16405ST-13">13</A>
Ogata Y.
Tabushi I.
J. Am. Chem. Soc.
1961,
83:
3440
<A NAME="RG16405ST-14">14</A>
Microwave-assisted reactions have been performed on a Milestone Microsynth Labstation,
dual magnetron system with pyramid diffuser, 1600 W power (800X2), maximum delivered
power 1000 W, Easywave software. Conditions: 200 W fixed power, 5 min irradiation.
<A NAME="RG16405ST-15A">15a</A>
Cardillo G.
Fabbroni S.
Gentilucci L.
Perciaccante R.
Tolomelli A.
Tetrahedron: Asymmetry
2004,
15:
593
<A NAME="RG16405ST-15B">15b</A>
Cardillo G.
De Simone A.
Mingardi A.
Tomasini C.
Synlett
1995,
1131 ; and reference cited therein
<A NAME="RG16405ST-16">16</A>
Compound 5: R
f
= 0.66 (8:2, cyclohexane-EtOAc). 1H NMR (300 MHz, CDCl3): δ = 1.03 (3 H, t, J = 7.2 Hz), 1.53-1.74 (2 H, m), 2.87 (1 H, dt, J = 1.5, 5.4 Hz), 3.34 (1 H, dd, J = 1.5, 8.4 Hz), 3.85 (1 H, d, J = 8.4 Hz), 5.25 (2 H, s), 7.38 (5 H, m). 13C NMR (75 MHz, CDCl3): δ = 9.6 (CH3), 24.3 (CH2), 43.9 (CH2), 57.0 (CH), 60.5 (CH), 67.9 (CH), 128.2 (CH), 128.4 (CH), 128.6 (CH), 134.8 (quat),
167.5 (CO). IR (film): 3021, 2968, 1744, 1498, 1456, 1380, 1296, 1257, 1157, 1010
cm-1.
Compound 6: R
f
= 0.57 (8:2, cyclohexane-EtOAc). 1H NMR (300 MHz, CDCl3): δ = 1.04 (3 H, t, J = 7.4 Hz), 1.91-2.06 (2 H, m), 4.24-4.54 (1 H, m), 5.21 (2 H, s), 6.00 (1 H, d, J = 15.4 Hz), 7.03 (1 H, dd, J = 15.4, 9.2 Hz), 7.25 (5 H, m). 13C NMR (75 MHz, CDCl3): δ = 12.1 (CH3), 31.2 (CH2), 52.9 (CH2), 66.6 (CH), 121.8 (CH), 128.6 (CH), 128.9 (CH), 129.9 (CH), 134.3 (quat), 135.7
(CH), 163.0 (CO). IR (film): 2955, 1867, 1755, 1442, 1252, 1218, 1994 cm-1.
<A NAME="RG16405ST-17">17</A>
Fujita M.
Ishizuka H.
Ogura K.
Tetrahedron Lett.
1991,
32:
6355
<A NAME="RG16405ST-18A">18a</A>
Bonini C.
Righi G.
Synthesis
1994,
225
<A NAME="RG16405ST-18B">18b</A>
Wang S.
Howe GP.
Mahal RS.
Procter G.
Tetrahedron Lett.
1992,
33:
3351
<A NAME="RG16405ST-19">19</A>
Ring-Opening of Epoxide 5.
To a stirred solution of epoxide 5 (1 mmol) in 5 mL of dry CH2Cl2 at -78 °C, TiCl4 (1 mL, solution 1 M in CH2Cl2) was added. The reaction was stirred at this temperature for 3 h and then quenched
with H2O. After diluting with CH2Cl2, the two phases were separated, the organic one was dried over Na2SO4 and solvent was removed under reduced pressure. Compound 7 was isolated, by flash chromatography on silica gel (cyclohexane-EtOAc, 8:2 as eluant).
Compound 7: R
f
= 0.52 (8:2, cyclohexane-EtOAc). 1H NMR (300 MHz, CDCl3): δ = 1.08 (3 H, t, J = 7.5 Hz), 1.68-1.85 (1 H, ddq, J = 7.5, 9.3, 14.4 Hz), 1.95-2.09 (1 H, ddq, J = 7.5, 3.0, 14.4 Hz), 3.25 (1 H, d, J = 7.8 Hz), 4.04 (1 H, ddd, J = 3.0, 9.3, 3.0 Hz), 4.12 (1 H, ddd, J = 3.0, 7.8, 5.4 Hz), 4.65 (1 H, d, J = 5.4 Hz), 5.25 (2 H, s), 7.39 (5 H, m). 13C NMR (75 MHz, CDCl3): δ = 10.7 (CH3), 25.0 (CH2), 43.9 (CH2), 65.0 (CH), 68.0 (CH), 76.0 (CH), 128.2 (CH), 128.3 (CH), 128.7 (CH), 134.6 (quat),
169.0 (CO). IR (film): 3457, 2953, 2919, 1734, 1261, 1013 cm-1
Formation of Epoxide 8.
To a stirred solution of 7 (1 mmol) in 5 mL of dry THF at 0 °C, NaH (1.1 equiv, 26.5 mg) was added. The reaction
was stirred at r.t. for 2 h and then quenched by addition of H2O. After removing THF under reduced pressure, the residue was diluted with EtOAc,
and washed twice with H2O. The organic layer was separated, dried over Na2SO4 and solvent was removed under reduced pressure. Compound 8 was isolated, by flash chromatography on silica gel (cyclohexane-EtOAc, 9:1 as eluent).
Compound 8: R
f
= 0.54 (8:2, cyclohexane-EtOAc). 1H NMR (300 MHz, CDCl3): δ = 1.10 (3 H, t, J = 8.1 Hz), 1.63-1.96 (2 H, m), 3.39 (1 H, dd, J = 1.5, 4.5 Hz), 3.48 (1 H, d, J& nbsp;= 1.5 Hz), 3.50 (1 H, dt, J = 4.5, 8.1 Hz), 5.26 (2 H, s), 7.39 (5 H, m). 13C NMR (75 MHz, CDCl3): δ = 10.2 (CH3), 28.9 (CH2), 52.8 (CH2), 59.9 (CH), 61.6 (CH), 67.5 (CH), 128.2 (CH), 128.4 (CH), 128.7 (CH), 134.9 (quat),
167.9 (CO). IR (film): 3034, 2963, 1747, 1497, 1455, 1381, 1264, 1190, 1026 cm-1.