Notes
J . Org. Chem., Vol. 61, No. 8, 1996 2909
Ta ble 1. â-Hyd r id e Elim in a tion of r-Dia zo Ca r bon yl
Eth yl 2-Acetyl-4-m eth ylh ep ta n oa te (5d ). From 1.67 g of
2-methylpentanyl iodide was obtained an inseparable mixture
of â-keto ester diastereomers 5d as a colorless oil (1.31 g, 78%).
TLC Rf (10% ethyl acetate/petroleum ether) ) 0.49; 1H NMR
(250 MHz, CDCl3) δ 4.17 (q, 2H, J ) 7.2 Hz), 3.47 (dd, 1H, J )
5.2, 7.9 Hz), 2.18 (s, 3H), 1.85 (m, 1H), 1.66 (m, 1H), 1.28 (m,
4H), 1.23 (t, 3H, J ) 7.2 Hz), 1.07 (m, 1H), 0.84 (d, 6H, J ) 6.4
Hz); 13C (62.9 MHz, CDCl3) δ up: 203.3, 170.0, 61.2, 39.2, 35.3,
19.8; down: 58.1, 30.6, 28.5, 19.3, 14.1, 14.0; IR (film) 2959, 2874,
1746, 1715, 1464, 1359, 1242, 1183, 1025 cm-1; EI MS m/ z (rel
intensity) 215 (M+ + 1, 1), 172 (26), 143 (17), 131 (22), 130 (67),
115 (41), 101 (100), 97 (15), 84 (14), 73 (77); HRMS (calcd for
Com p ou n d s 1
C
12H23O3) 215.1647, found 215.1652.
Meth yl (E)-2-Acetyl-5-p h en ylp en ta n oa te (5e). From 3.00
g of cinnamyl bromide was obtained the â-keto ester 5e as a
colorless oil (3.29 g, 93%). TLC Rf (10% ethyl acetate/petroleum
1
ether) ) 0.49; H NMR (250 MHz, CDCl3) δ 7.31 (m, 5H), 6.46
(d, 1H, J ) 15.8 Hz), 6.12 (dt, 1H, J ) 7.1, 15.8 Hz), 3.74 (s,
3H), 3.62 (t, 1H, J ) 7.4 Hz), 2.76 (t, 2H, J ) 7.3 Hz), 2.26 (s,
3H); 13C (62.9 MHz, CDCl3) δ up: 202.1, 169.6, 136.9, 31.5;
down: 132.7, 128.4 (× 2), 127.3, 126.1 (× 2), 125.6, 57.3, 52.3,
29.2; IR (film) 2926, 2855, 1743, 1718, 1644, 1466, 1358, 1242,
1151, 1120 cm-1; EI MS m/ z (rel intensity) 232 (M+, 34), 190
(26), 189 (51), 168 (33), 156 (100), 131 (54), 130 (39), 119 (69),
116 (56), 104 (18), 91 (88), 77 (18); HRMS (calcd for C14H16O3)
232.1099, found 232.1082.
P r epar ation of Meth yl 2-Diazou n decan oate (1a). Method
A: Sodium hydride (60% in mineral oil, 0.151 g, 3.78 mmol) was
washed three times with petroleum ether and then suspended
in 10 mL of dry diethyl ether at 0 °C under nitrogen. To this
solution was then added dropwise 0.611 g (2.52 mmol) of â-keto
ester 5a in 3 mL of diethyl ether. After the mixture had stirred
for 10 min, 0.915 g (7.56 mmol) of methanesulfonyl azide was
added dropwise, and the mixture was allowed to warm to rt over
5 h. The mixture was then diluted with 10 mL of 10% aqueous
NaOH and extracted three times with 25 mL of ethyl acetate.
The organic layers were then washed with brine, dried over Na2-
SO4, concentrated in vacuo, and chromatographed to give the
R-diazo ester 1a as a yellow oil (0.531 g, 93%). TLC Rf (10%
ethyl acetate/petroleum ether) ) 0.83; 1H NMR (250 MHz,
CDCl3) δ 3.67 (s, 3H), 2.22 (t, 2H, J ) 7.0 Hz), 1.42 (m, 2H),
1.19 (m, 12H), 0.80 (m, 3H); 13C (62.9 MHz, CDCl3) δ up: 167.9,
31.8, 29.4, 29.1, 28.6, 27.5, 23.0 (× 2), 22.6; down: 51.6, 13.9;
IR (film) 2926, 2855, 2360, 2079, 1699, 1436, 1351, 1136, 739
cm-1; EI MS m/ z (rel intensity) 199 (M+ - N2, 2), 167 (6), 137
(2), 124 (8), 113 (100), 100 (30), 87 (43), 81 (60), 69 (37).
Eth yl 2-Dia zou n d eca n oa te (1b). Method A: From 1.284
g of â-keto ester 5b was obtained the R-diazo ester 1b as a yellow
oil (0.915 g, 76%). TLC Rf (10% ethyl acetate/petroleum ether)
three times with petroleum ether and then suspended in 10 mL
of dry DME and cooled to 0 °C under nitrogen. Methyl
acetoacetate (2.16 mL, 20.0 mmol) was added dropwise to give
a solid mass. nBu4NI (0.21 g, 1.0 mmol) was added, followed
by 1-bromononane (1.91 mL, 10.0 mmol), and the reaction was
stirred at 80 °C for 20 h. The mixture was cooled to rt, diluted
with 10 mL of 5% aqueous HCl and extracted three times with
20 mL of petroleum ether. The combined organic extracts were
dried over Na2SO4, concentrated in vacuo, and chromatographed
to give the R-alkylated â-keto ester 5a as a colorless oil (1.99 g,
82%). TLC Rf (10% ethyl acetate/petroleum ether) ) 0.73; 1H
NMR (250 MHz, CDCl3) δ 3.62 (s, 3H), 3.33 (t, 1H, J ) 7.4 Hz),
2.11 (s, 3H), 1.71 (m, 2H), 1.15 (m, 14 H), 0.77 (m, 3H); 13C (62.9
MHz, CDCl3) δ up: 202.8, 170.1, 31.6, 29.1 (× 2), 28.0 (× 2),
27.2 (× 2), 22.4; down: 59.4, 52.0, 28.4, 13.8; IR (film) 2924, 2855,
1746, 1721, 1645, 1435, 1358, 1152 cm-1; EI MS m/ z (rel
intensity) 242 (M+, 1), 200 (7), 157 (6), 129 (11), 116 (60), 87
(100), 74 (23), 59 (12).
1
) 0.88; H NMR (250 MHz, CDCl3) δ 4.14 (q, 2H, J ) 7.1 Hz),
2.22 (t, 2H, J ) 7.1 Hz), 1.43 (m, 2H), 1.20 (m, 15H), 0.81 (m,
3H); 13C (62.9 MHz, CDCl3) δ up: 167.6, 60.6, 31.8, 29.4, 29.2
(× 2), 28.7, 27.5, 22.9, 22.6; down: 14.4, 14.0; IR (film) 2928,
2856, 2084, 1699, 1465, 1371, 1304, 1134, 739 cm-1; EI MS m/ z
(rel intensity) 167 (M+ - N2, - OEt, 2), 127 (13), 99 (32), 88
(22), 81 (23), 69 (23), 55 (100).
ter t-Bu tyl 2-Dia zou n d eca n oa te (1c). Method A: From
0.658 g of â-keto ester 5c was obtained the R-diazo ester 1c as
a yellow oil (0.452 g, 73%). TLC Rf (5% ethyl acetate/petroleum
ether) ) 0.77; 1H NMR (250 MHz, CDCl3) δ 2.22 (t, 2H, J ) 7.0
Hz), 1.45 (s, 9H), 1.24 (m, 14H, 0.85 (m, 3H); IR (film) 3428,
2957, 2856, 2078, 1694, 1456, 1368, 1133 cm-1; EI MS m/ z (rel
intensity) 167 (M+ - N2, - tBuO, 6), 124 (5), 111 (2), 101 (3), 99
(24), 81 (11), 73 (7), 57 (100).
Eth yl 2-Acetylu n d eca n oa te (5b). From 1.00 mL of 1-bro-
mononane was obtained the â-keto ester 5b as a colorless oil
(1.16 g, 86%). TLC Rf (10% ethyl acetate/petroleum ether) )
0.54; 1H NMR (250 MHz, CDCl3) δ 4.19 (q, 2H, J ) 7.2 Hz),
3.40 (t, 1H, J ) 7.5 Hz), 2.22 (s, 3H), 1.82 (m, 2H), 1.25 (m, 15H),
0.87 (m, 3H); 13C (62.9 MHz, CDCl3) δ up: 203.2, 169.8, 61.1,
31.8, 29.4, 29.2, 28.1, 27.3, 22.6; down: 59.8, 28.6, 14.0; IR (film)
2926, 2855, 1743, 1718, 1644, 1466, 1358, 1242, 1151, 1120 cm-1
;
Eth yl 2-Dia zo-4-m eth ylh ep ta n oa te (1d ). Method B: To
a solution of the â-keto ester 5d (1.14 g, 5.3 mmol) and
EI MS m/ z (rel intensity) 257 (M+, 3), 214 (32), 171 (12), 157
(16), 143 (23), 130 (97), 101 (100), 72 (66); HRMS (calcd for
p-nitrobenzenesulfonyl azide (2.43 g, 10.6 mmol) in 30 mL of
dry CH2Cl2 under nitrogen at 0 °C was added dropwise DBU
(1.6 mL, 10.6 mmol). The mixture was stirred for 90 min, after
which 30 mL of 10% NaOH soln was added, and the mixture
was warmed to rt. The crude R-diazo ester was extracted three
times with CH2Cl2, washed with brine, dried over Na2SO4,
concentrated in vacuo, and chromatographed to provide the
R-diazo ester 1d as a yellow oil (0.83 g, 79%). TLC Rf (10% ethyl
C
15H28O3) 256.2038, found 256.2058.
ter t-Bu tyl 2-Acetylu n d eca n oa te (5c). From 4.78 mL of
1-bromononane was obtained the â-keto ester 5c as a colorless
oil (5.11 g, 72%). TLC Rf (10% ethyl acetate/petroleum ether)
1
) 0.69; H NMR (250 MHz, CDCl3) δ 3.21 (t, 1H, J ) 7.4 Hz),
2.12 (s, 3H), 1.67 (m, 2H), 1.38 (s, 9H), 1.17 (m, 12H), 0.79 (m,
3H); 13C (62.9 MHz, CDCl3) δ up: 203.0, 168.5, 81.0, 31.2, 28.9,
28.7 (× 2), 28.6, 27.5, 26.7, 22.0; down: 60.4, 27.9, 27.3 (× 3),
13.4; IR (film) 2925, 2855, 1714, 1641, 1460, 1368, 1250, 1148,
848 cm-1; EI MS m/ z (rel intensity) 211 (M+ - tBuO, 1), 158
(1), 112 (3), 103 (13), 102 (15), 98 (16), 57 (100).
1
acetate/petroleum ether) ) 0.75; H NMR (250 MHz, CDCl3) δ
4.22 (q, 2H, J ) 7.2 Hz), 2.19 (ddd, 2H, J ) 6.1, 14.9, 36.9 Hz),
2.10 (m, 1H), 1.31 (m, 4H), 1.27 (t, 3H, J ) 7.2 Hz), 0.92 (d, 6H,
J ) 6.7 Hz); 13C (62.9 MHz, CDCl3) δ up: 60.7, 38.4, 30.6, 20.0;