Helvetica Chimica Acta ± Vol. 86 (2003)
297
1
oxide; hexane/AcOEt 10 :1). Yield 32%. GC/MS: t
R
14.50 min. H-NMR (CDCl
3
): 3.84 (s, COOMe); 3.81 (s,
COOMe); 3.60 (m, HÀC(8a)); 1.25 (s, Me); 1.80 ± 1.50 (other H-atoms). 13C-NMR (CDCl
): 169.4 (COOMe);
3
1
45.0 (C(3)); 100.1 (C(3a)); 87.0 (C(1)); 55.5, 54.2 (MeO); 48.2 (C(8a)); 29.8 (C(4)), 29.7, 29.0, 25.1 (other C-
atoms); 14.3 (Me). EI-MS: 269 (4, [M 1] ), 241 (100), 223 (19), 209 (47), 181 (9), 162 (25), 149 (15), 139 (4),
21 (8), 93 (7), 79 (9), 59 (11). Anal. calc. for C14 (268.3): C62.67, H 7.51; found: C62.95, H 7.27.
Trimethyl 5a,6,7,8,9,10-hexahydro-2-methoxy-3a-methyl-3,4-dioxacyclopenta[c]azulene-1,5,5-tricarboxylate.
1
20 5
H O
This compound was the minor product (35%) in the GS/MS analysis; not isolated in pure form. GCand GC-MS
data (from crude fractions) are provided only. GC/MS: t
74), 181 (100), 148 (50), 121 (18), 93 (52), 79 (21), 59 (17).
The Reaction of 1-(2-Methylcyclopent-1-enyl)ethanone with DMDM. The only isolated product was
R
16.57 min. EI-MS: 398 (4, M ), 268 (60), 224 (6), 208
(
dimethyl 2,3-bis(methoxycarbonyl)succinate.
The Reactions of 4-Methylpent-3-en-2-one and Methyl Vinyl Ketone with DMDM and EADA. The reactions
gave oligomers, and likely carbene-originated products could not be identified. The crude reaction mixtures
were extracted with hot hexane to discard polymeric material, but it was unsuccessful. The only isolated
products were saturated and unsaturated dimerization products of DMDM and EADA.
Dimethyl 5-Ethyl-2,3-dihydro-4-methyl-3-phenyl-furan-2,2-dicarboxylate (14). This compound was the
main product (92%) in the GS/MS analysis. The oily compound was purified by prep. TLC(silica gel; hexane/
1
AcOEt/CHCl
CDCl
3
4 :1:1; extraction of zone around R
f
ca. 0.6). Yield 35%. GC/MS: t
R
15.04 min. H-NMR
(
3
): 7.35 ± 7.14 (m, 5 arom. H); 4.71 (br. s, HÀC(3)); 3.52 (s, COOMe); 3.16 (s, COOMe); 2.30 (m, C H
2
);
1
3
1
(
.45 (s, Me); 1.17 (t, J 7.5, MeCH
2
). C-NMR (CDCl ): 169.04, 166.78 (2 COOMe); 152.69 (C(5)); 137.23
3
C(1) of Ph); 129.13, 128.12, 127.52 (arom. C-atoms); 105.07 (C(4)); 90.80 (C(2)); 59.06 (C(3)); 53.23, 51.98 (2
MeO); 19.02 (CH
16), 128 (28), 115 (19), 91 (7), 77 (8), 59 (21). Anal. calc. for C17
H 6.60.
2
); 11.78 (MeCH
2
); 9.78 (Me). EI-MS: 304 (2, M ), 272 (12), 244 (100), 229 (65), 213 (40), 171
(
20 5
H O (304.3): C67.09, H 6.62; found: C67.54,
Methyl 2-Acetyl-2,3-dihydro-5-methyl-3-(2,6,6-trimethylcyclohex-2-enyl)-furan-2-carboxylate (15). Not iso-
lated in pure form; GC and GC/MS data (from crude fractions) are provided only. GC/MS showed 8 different
peaks all with same molecular weight and similar fragmentation pattern. This may be attributed to the presence
of 8 possible diastereoisomers (3 apparent stereogenic centers and one for the rotational barrier). GC/MS: t
R
1
4.09 min: EI-MS: 320 (2, M ), 253 (0.5), 193 (14), 183 (57), 165 (21), 125 (78), 124 (74), 109 (24), 105 (7), 91
(11), 56 (21), 43 (100). GC/MS: t
R
15.21 min. EI-MS: 320 (2, M ), 283 (2), 254 (6), 193 (8), 183 (7), 165 (6), 125
(
77), 109 (60), 105 (15), 91 (13), 44 (100), 43 (96). GC/MS: t
R
16.09 min. EI-MS: 320 (3, M ), 278 (2), 262 (4),
1
90 (25), 121 (19), 105 (13), 93 (31), 91 (51), 44 (100), 43 (72). GC/MS: t
R
16.30 min. EI-MS: 320 (3, M ), 276
(
(
(
(
(
3), 175 (7), 155 (93), 127 (38), 109 (38), 91 (17), 81 (10), 44 (100), 43 (64). GC/MS: t
R
17.03 min. EI-MS: 320
2, M ), 264 (4), 221 (26), 165 (20), 149 (16), 125 (7), 121 (26), 107 (17), 93 (49), 91 (41), 77 (26), 44 (100), 43
69). GC/MS: t
11), 91 (28), 44 (41). GC/MS: t
R
17.30 min. EI-MS: 320 (2, M ), 256 (18), 155 (100), 127 (45), 125 (23), 109 (29), 107 (58), 105
R
17.52 min. EI-MS: 320 (2, M ), 282 (2), 278 (11), 259 (5), 247 (3), 155 (18), 125
59), 111 (17), 109 (26), 107 (36), 91 (20), 44 (100). GC/MS: t
R
19.49 min. EI-MS: 320 (2, M ), 295 (1), 293 (2),
2
(
54 (79), 239 (30), 197 (12), 183 (92), 153 (19), 128 (37), 91 (17), 44 (100). 1H-NMR (CDCl
3
): 6.40 ± 5.80
(4'),
HÀC(3')); 4.50 ± 4.10 (MeCH
2
, HÀC(3), HÀC(4)); 2.29, 2.27, 2.18 (COOMe); 1.88, 1.77, 1.54 (CH
2
Me(2'), MeÀC(5), HÀC(1')); 1.26 (CH
2
2
(5')); 1.06, 0.90, 0.83 (MeCH , 2 Me(6')).
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[
[
[
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