1.1 equiv). The allyl iodide (2.0 mL, 167.98 g/mol, 1.1 equiv) was
then added, and the resulting mixture was allowed to reach room
temperature and stirred for 1.5 h. The reaction was quenched
with a saturated solution of ammonium chloride, and the product
was extracted 3 times with diethyl ether. The organic layers
were combined, washed with brine, and dried over MgSO4, and
the solvents were removed under vacuum. The crude was
purified by silica gel chromatography to afford pure 6 in 70%
yield.
with ethyl acrylate in dichloromethane using 10% of 2
the difference in conversion and yield is not notably
different. Likewise, when a solution of ethyl acrylate and
5% of 2 was irradiated or heated in dichloroethane in a
sealed tube, the yield and conversion were similar. In
these two cases, the difference between classical and mi-
crowave conditions was not significant. Garbacia came
to similar conclusions in studies on ring-closing metathe-
sis.2i In our studies, the rate acceleration seems to be due
to the high temperature, higher pressure, and the ease
to which microwave irradiation reaches them.
In conclusion, microwave irradiation is a convenient
way to generate high temperatures and somewhat el-
evated pressures (4-5 Barr) rapidly. This can drive the
cross-metathesis reaction to proceed in short reaction
times with low catalyst load. In the case of coupling
between a terminal olefin and an unactivated double
bond or between two unactivated double bonds the yields
or the selectivity of the reactions are not changed.
1
C9H14O3. Mol wt: 170.21 g/mol. H NMR (300 MHz CDCl3):
δ 5.80 (ddt, 3J ) 16.8, 10.2, 6.5 Hz; 1H); 5.03 (dd, 3J ) 16.8, 1.5
3
3
Hz; 1H); 4.97 (dd, J ) 10.2, 1.5 Hz; 1H); 4.17 (q; J ) 7.2 Hz;
2H); 3.45 (s; 2H); 2.66 (t; 3J ) 7.2 Hz; 2H); 2.33 (pq; 3J ) 7.2
Hz; 2H); 1.27 (t; 3J ) 7.2 Hz; 3H). Enolic proton: 12.14 (s; 0.08H).
13C NMR (75.45 MHz; CDCl3): δ 201.6 (C); 166.6 (C); 136.2 (CH);
114.8 (CH2); 60.6 (CH2); 48.7 (CH2); 41.4 (CH2), 26.9 (CH2); 13.5
(CH3). IR: ν-1 3080; 2980; 2920; 1750; 1730; 1710; 1640; 1410;
1370; 1320; 1240; 1030; 920. MS m/z (relative intensity): 171
M + H+ [100]; 193 M + Na+ [30]. HRMS: calcd 171.1021, found
171.1017.
Ethyl 7-(Diethoxyphosphoryl)-6-oxohept-2-enoate 4. C13-
H
23O6P. Mol wt: 306.29 g/mol. 1H NMR (300 MHz CDCl3): δ
6.92 (dt; 3J ) 15.7, 6.7 Hz; 1H); 5.84 (d; 3J ) 15.7 Hz; 1H); 4.19
(q; 3J ) 7.2 Hz; 3JP ) 7.2 Hz; 4H); 4.14 (q; 3J ) 7.2 Hz; 2H);
Experimental Section
2
3
3.09 (d, JP ) 22.8 Hz; 2H); 2.81 (t; J ) 7.2 Hz; 2H); 2.49 (pq;
3J ) 7.0 Hz; 2H); 1.34 (t; 3J ) 7.2 Hz; 6H); 1.28 (t; 3J ) 7.2 Hz;
3H). Enolic proton: 12.14 (s, 0.15H). 13C NMR (100.6 MHz;
CDCl3): δ 199.2 (C); 166.0 (C); 146.5 (CH); 121.8 (CH); 62.4
(CH2); 62.3 (CH2); 59.9 (CH2), 42.1 (d; 2JP ) 127 Hz; CH2); 41.5
(CH2); 25.3 (CH2); 16.0 (CH3); 15.9 (CH3); 13.9 (CH3). IR: ν-1
2980; 2940; 2910, 1720; 1650; 1310; 1270; 1180; 1040. MS m/z
(relative intensity): 307 M + H+ [100]; 329 M + Na+ [95]; 635
2M + Na+ [60]. HRMS: calcd 307.1310, found 307.1312. Anal.
Calcd: C, 50.98; H, 7.58. Found: C, 51.36; H, 7.61.
General Procedure for Cross-Metathesis under Micro-
wave Irradiation. To a solution of olefin in dichloromethane
was added the acrylate ester (or vinyl ketone) followed by the
catalyst. To ensure a homogeneous system, all of the batches
were prestirred for 15 s before the irradiations were initiated.
The vial was sealed and irradiated in a microwave reactor at
the desired temperature for the appropriate time (see Tables
2-4). All of the microwave irradiations were carried out with a
Personal Chemistry, Emrsy Optimiser 1-300 W. All of the
experiments were carried out at a 10-1M concentration. The
program information is available in the Supporting Information.
When the vial was removed from the apparatus, the solvent was
evaporated under vacuum, and the crude was analyzed by 1H
NMR and subsequently purified via silica gel chromatography.
Diethyl (2-Oxohex-5-enyl)phosphonate 3. To a suspension
of sodium hydride in 60% mineral oil (480 mg, 24.00 g/mol, 1
equiv) in dried THF (0.4 M) was added, at 0 °C, the diethyl (2-
oxopropyl)phosphonate 3a (3.8 mL, 194.17 g/mol, 1 equiv). The
resulting mixture was stirred for 1 h at 0 °C. Then, a solution
of n-butyllithium in hexanes (8.8 mL, 2.5 M, 1.1 equiv) was
added dropwise to the mixture at 0 °C and stirred for 1 h at 0
°C. The allyl iodide (2.2 mL, 167.98 g/mol, 1.2 equiv) was then
added, the resulting mixture was allowed to reach room tem-
perature and stirred during 3 h. The reaction was quenched with
5% aqueous HCl, and the product was extracted with chloroform.
The system was dried over MgSO4, and the solvents were
removed under vacuum. The crude was purified by silica gel
chromatography to afford pure 3 in 75% yield.
Diethyl 6-Oxo-oct-2-enedioate 7. C12H18O5. Mol wt: 242.27
g/mol. 1H NMR (300 MHz CDCl3): δ 6.92 (dt; 3J ) 15.7, 6.8 Hz;
3
3
1H); 5.84 (d; J ) 15.7 Hz; 1H); 4.19 (q; J ) 7.2 Hz; 2H); 4.17
(q; 3J ) 7.2 Hz; 2H); 3.47 (s, 2H); 2.76 (t; 3J ) 7.1 Hz; 2H); 2.49
(pq; 3J ) 7.0 Hz; 2H); 1.28 (t; 3J ) 7.2 Hz; 3H); 1.27 (t; 3J ) 7.2
Hz; 3H). Enolic proton: 12.14 (s, 0.15H). 13C NMR (75.45 MHz;
CDCl3): δ 200.5 (C); 166.3 (C); 165.2 (C); 146.2 (CH); 121.2 (CH);
60.3 (CH2); 59.2 (CH2); 48.2 (CH2), 39.8 (CH2); 24.8 (CH2); 13.3
(CH3); 13.2 (CH3). IR: ν-1 2970; 2920; 1710; 1650; 1310; 1270;
1190; 1040. MS m/z (relative intensity): 243 M + H+ [58]; 260
[100]; 265 M + Na+ [34]. HRMS: calcd 243.1233, found
243.1240. Anal. Calcd: C, 59.49; H, 7.49. Found: C, 59.66; H,
7.66.
Diethyl Oct-2-enedioate 9. C12H20O4. Mol wt: 228.28 g/mol.
3
1H NMR (300 MHz CDCl3): δ 6.57 (dt; J ) 15.6, 6.9 Hz; 1H);
5.46 (d; 3J ) 15.6 Hz; 1H); 3.79 (q; 3J ) 6.9 Hz; 2H); 3.74 (q; 3J
3
3
) 6.9 Hz; 2H); 1.95 (t; J ) 7.0 Hz; 2H); 1.87 (pq; J ) 6.9 Hz;
2H); 1.29 (pp; 3J ) 7.0 Hz; 2H); 1.15 (pp; 3J ) 7.0 Hz; 2H); 0.90
(t; J ) 6.9 Hz; 3H); 0.88 (t; J ) 6.9 Hz; 3H). 13C NMR (100.6
MHz; CDCl3): δ 172.1 (C); 165.3 (C); 147.6 (CH); 120.9 (CH);
59.4 (CH2); 59.1 (CH2); 33.0 (CH2); 31.0 (CH2), 27.8 (CH2); 23.6
(CH2); 13.4 (CH3); 13.3 (CH3). IR: ν-1 2980; 2930; 2870; 1720;
1650; 1400; 1270; 1180; 1040. MS m/z (relative intensity): 229
M + H+ [100]; 71 M + Na+ [7]; 328 [95]. HRMS: calcd 229.1440,
found 229.1432. Anal. Calcd: C, 63.14; H, 8.83. Found: C, 62.77;
H, 8.45.
3
3
C10H19O4P. Mol wt: 234.23 g/mol. 1H NMR (300 MHz
CDCl3): δ 5.81 (ddt; 3J ) 16.9, 10.2, 6.5 Hz; 1H); 5.05 (dd, 3J )
3
3
16.9, 1.5 Hz; 1H); 4.98 (dd, J ) 10.2, 1.5 Hz; 1H); 4.15 (dq; J
) 7.2, 7.2 Hz; 4H); 3.09 (d; 2JP ) 22.8 Hz; 2H); 2.74 (t; 3J ) 7.2
Hz; 2H); 2.34 (pq; 3J ) 7.2 Hz; 2H); 1.34 (t; 3J ) 7.2 Hz; 6H).
13C NMR (75.45 MHz; CDCl3): δ 200.0 (C); 135.9 (CH); 114.3
(CH2); 61.6 (CH2); 61.5 (CH2); 42.0 (CH2), 41,4 (d; 2JP ) 126 Hz;
CH2); 26.5 (CH2); 15.4 (CH3); 15.3 (CH3). IR: ν-1 2980; 2910;
1720; 1640; 1400; 1260; 1020; 960. MS m/z (relative intensity):
235 M + H+ [27]; 257 M + Na+ [7]; 468 2M + Na+ [100]. Anal.
Calcd: C, 51.28; H, 8.18. Found: C, 51.65; H, 8.32. HRMS: calcd
235.1099, found 235.1111.
Supporting Information Available: General experimen-
tal procedures, microwave programs, CAS numbers for known
1
compounds, and H and 13C spectra for compounds 3, 4, 6, 7,
and 9. This material is available free of charge via the Internet
Ethyl 5-Oxohept-2-enoate 6. To a solution of enolate (3 g,
152.13 g/mol, 1 equiv) in dried THF (100 mL, 0.2 M) was added
dropwise, at 0 °C, n-butyllithium in hexanes (8.7 mL, 2.5 M,
JO0514624
J. Org. Chem, Vol. 70, No. 23, 2005 9639