Notes
J . Org. Chem., Vol. 63, No. 8, 1998 2757
H, J ) 7.2 Hz); IR (neat) 1739, 1174; MS m/z (relative intensity)
(EI, 70 eV) 172 (M+, 1), 143 (5), 129 (12), 127 (26), 101 (100), 88
(90), 73 (38). Anal. Calcd for C10H20O2: C, 69.720; H, 11.703.
Found: C, 69.836; H, 11.862.
Eth yl 3-(1-Cycloh exen yl)p r op ion a te (11): 1H NMR (200
MHz, CDCl3): δ 1.25 (t, 3 H, J ) 7.1 Hz), 1.43-1.68 (m, 4 H),
1.92-1.95 (m, 4 H), 2.24 (t, 2 H, J ) 7.1 Hz), 2.40 (t, 2 H, J )
7.1 Hz), 4.13 (q, 2 H, J ) 7.1 Hz), 5.41 (s, 1 H); IR (neat) 1737,
1176; MS m/z (relative intensity) (EI, 70 eV) 182 (M+, 23), 153
(1), 137 (26), 109 (12), 95 (100), 81 (29). Anal. Calcd for
C
11H18O2: C, 72.487; H, 9.955. Found: C, 72.253; H, 10.171.
Eth yl exo-2-Nor bor n yl Aceta te (19). The exo orientation
of the ethyl acetate group was confirmed by 13C DEPT, HET-
COR, and NOESY experiments. 1H NMR (300 MHz, CDCl3): δ
1.00-1.13 (m, 3 H), 1.17-1.29 (m, 2 H), 1.26 (t, 3 H, J ) 7.1
Hz), 1.44-1.51 (m, 3 H), 1.84-1.88 (m, 1 H), 1.95-1.96 (m, 1
H), 2.05-2.12 (m, 1 H), 2.18-2.28 (m, 2 H), 4.09 (q, 2 H, J ) 7.1
Hz); 13C NMR (75 MHz, CDCl3): δ 13.96, 28.29, 29.52, 34.96,
36.50, 37.50, 38.24, 40.92, 41.12, 59.91, 173.45; IR (neat) 1737,
1178; MS m/z (relative intensity) (EI, 70 eV) 182 (M+, 3), 153
(17), 137 (34), 113 (100), 109 (26), 95 (76), 67 (92). Anal. Calcd
for C11H18O2: C, 72.487; H, 9.955. Found: C, 72.226; H, 10.295.
Eth yl (2-Meth yl-1-cycloh exen yl)a ceta te (20a ) a n d Eth yl
(2-Meth yl-2-cycloh exen yl)a ceta te (20b). The assignment of
the two structural isomers was derived from hydrogenation of
the isomers using BER-Ni2B (cat.) and Pd/C. The isomers were
not hydrogenated with BER-Ni2B (cat.) at 65 °C in methanol.
This result showed that the two isomers should be tri- or
tetraolefinic ester.6 And we observed that only one of the two
isomers was readily hydrogenated over Pd/C, whereas, the other
was very slowly hydrogenated. It is confidently believed that
the isomers are tri- and tetraolefinic esters. The ratio of
tetrasubstituted to trisubstituted olefinic ester (20a :20b) was
5:4 as determined by a NMR spectrum; 1H NMR (300 MHz,
CDCl3, characteristic signals): δ 2.99 (s, 1.11 H, R-hydrogens
of ester group in 20a ), 5.43 (brs, 0.44 H, olefinic hydrogen in
20b); IR (neat) 1739, 1163; 20a : 13C NMR (75 MHz, CDCl3): δ
13.95, 21.65, 22.78, 22.92, 29.94, 31.61, 38.85, 60.14, 129.14,
135.34, 173.67; MS m/z (relative intensity) (EI, 70 eV) 182 (M+,
55), 153 (2), 137 (4), 109 (55), 108 (100), 95 (21), 93 (60), 67 (39);
20b: 13C NMR (75 MHz, CDCl3): δ 13.95, 18.82, 19.11, 25.13,
27.88, 35.38, 37.97, 60.10, 123.72, 128.91, 172.47; MS m/z
(relative intensity) (EI, 70 eV) 182 (M+, 8), 153 (1), 137 (5), 108
(29), 95 (56), 94 (100), 79 (34). Anal. Calcd for C11H18O2: C,
72.487; H, 9.955. Found: C, 72.330; H, 10.216.
F igu r e 1.
Con clu sion
In conclusion, the coupling reaction of alkenes with
R-bromo acid derivatives in the presence of excess NaI
can be carried out using Ni2B-BER in methanol. The
reactions of monosubstituted alkenes and norbornene
give the corresponding γ-iodo carboxylates with a limited
amount of reagents, but the corresponding deiodinated
products at standard conditions, whereas 1,1-disubsti-
tuted and trisubstituted alkenes give the corresponding
coupling products, unsaturated carboxylates. The Ni2B-
BER-methanol system tolerates many functional groups
such as acetals, esters, amides, nitriles, and epoxides and
has another advantage of a simple workup and mild
conditions.
Exp er im en ta l Section
Gen er a l P r oced u r e. BER (5 equiv, 10 mmol) was added to
the methanol solution (4 mL) of Ni(OAc)2‚4H2O (0.15 equiv, 0.3
mmol) and NaI (7.5 equiv, 15 mmol) with gentle stirring at room
temperature. Immediately a black coating of Ni2B on BER and
slow hydrogen evolution were observed. After 1 min, the
reaction was started by the addition of a methanol solution (2
mL) of methylenecyclohexane (0.192 g, 2 mmol) and ethyl
bromoacetate (0.835 g, 2.5 equiv, 5 mmol) at room temperature
(standard conditions). After 3 h, the Ni2B-BER was filtered,
and the filtrate was evaporated under reduced pressure. The
crude product was chromatographed on a silica gel column
(eluent; hexane/EtOAc 49:1) to give 0.331 g (91%) of ethyl 3-(1-
cyclohexenyl)propionate.
Ack n ow led gm en t. We are grateful to the Organic
Chemistry Research Center/KOSEF for financial sup-
port and to the Daewoo Foundation for the Post Gradu-
ate Scholarship given to Meyoung J u J oung.
Eth yl 4-Iod on on a n oa te (4): 1H NMR (200 MHz, CDCl3):
δ 0.90 (t, 3 H, J ) 7.2 Hz), 1.24-1.33 (m, 9 H), 1.82-1.94 (m, 2
H), 2.07 (q, 2 H, J ) 7.5 Hz), 2.50 (t, 2 H, J ) 7.5 Hz), 4.07-
4.21 (m, 1 H), 4.14 (q, 2 H, J ) 7.2 Hz); IR (neat) 1736, 1181;
MS m/z (relative intensity) (EI, 70 eV) 267 (5), 185 (57), 139
(55), 121 (50), 97 (85), 81 (26), 69 (100), 55 (97). Anal. Calcd
for C11H21O2I: C, 42.318; H, 6.781. Found: C, 42.243; H, 6.868.
E t h yl 4-Met h ylh ep t a n oa t e (9): 1H NMR (200 MHz,
CDCl3): δ 0.86-1.69 (m, 16 H), 2.25-2.34 (m, 2 H), 4.13 (q, 2
Su p p or tin g In for m a tion Ava ila ble: IR, NMR, MS, and
elemental analyses of 16 compounds and copies of spectra (1H
NMR, 13C NMR, DEPT) of 20a and 20b (5 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
J O972019Z