4136
F. Lieb et al. / Tetrahedron 57 (2001) 4133±4137
NMR +200 MHz, CDCl ) d 1.65 +s, 3H, CH ), 1.75 +s, 3H,
3
1H, OH), 7.0 +s, 2H, aromatic); HR-MS: C H O calcdfor
19 22 3
3
1
[M1H] 299.16417, foundm/z 299.16415.
CH ), 2.00 +s, 3H, mesityl CH ), 2.02 +s, 3H, mesityl CH ),
3
3
3
2
6
2
.22 +s, 3H, mesityl CH ), 5.08 and5.15 +s, 1H, H CC),
3
2
1
.8 +s, 2H, aromatic); HR-MS: C H O calcdfor [M 1H]
1
11c couldnot be isolated. However, the presence of 11c was
deduced from HPLC analysis by analogy with the other
products.
7
20
3
73.14852, foundm/z 273.14854.
1
.1.6. 6-Cyclopentyl-4-hydroxy-3-mesityl-2H-pyran-2-
1
one ꢀ7a). Yield: 48%; mp 200±2028C. H NMR +200
MHz, CDCl ) d 1.6±1.85 +m, 6H, CH ), 1.9±2.1 +m, 2H,
CH ), 2.12 +s, 6H, mesityl CH ), 2.28 +s, 3H, mesityl CH ),
1.2.3. 8-tert-Butyl-4-hydroxy-3-mesityl-5,6,7,8-tetrahydro-
2H-chromen-2-one ꢀ11d). Yellow solid, mp 172±1758C;
3
2
1
H NMR +200 MHz, CD OD) d 1.12 +s, 9H, t-Bu), 1.45±
3
2
3
3
2
aromatic); HR-MS: C H O calcdfor [M 1H]
.9 +m, 1H, CH-CCH), 6.0 +s, 1H, HCC), 6.95 +s, 2H,
1.80 +m, 3H, CH ), 1.85±2.05 +m, 2H, CH ), 2.08 +s, 3H,
2
mesityl CH ), 2.10 +s, 3H, mesityl CH ), 2.30 +s, 3H, mesityl
3 3
2
1
1
9
22
3
2
99.16417, foundm/z 299.16408.
CH ), 2.50±2.65 +m, 2H, CH ), 6.95 +s, 2H, aromatic); HR-
3 2
1
MS: C H O calcdfor [M 1H] 341.21112, foundm/z
341.21109.
2
2
28
3
1
.1.7. 6-Cyclohexyl-4-hydroxy-3-mesityl-2H-pyran-2-one
7b). Yield: 71%; mp 234±2368C. H NMR +200 MHz,
1
ꢀ
CDCl ) d 1.15±1.45 +m, 4H, CH ), 1.65±1.9 +m, 4H,
1.2.4. 8-Chloro-4-hydroxy-3-mesityl-5,6,7,8-tetrahydro-
2H-chromen-2-one ꢀ11e). White solid, mp 156±1588C;
3
2
CH ), 1.95±2.05 +m, 2H, CH ), 2.1 +s, 6H, mesityl CH ),
2
2
5
2
3
1
.25 +s, 3H, mesityl CH ), 2.35±2.5 +m, 1H, CH-CCH),
H NMR +200 MHz, CDCl ) d 1.85±2.15 +m, 1H, CH ),
3
3
2
.95 +s, 1H, HCC), 6.95 +s, 2H, aromatic); HR-MS:
2.12 +s, 3H, mesityl CH ), 2.15 +s, 3H, mesityl CH ),
3 3
2.05±2.25 +m, 2H, CH ), 2.32 +s, 3H, mesityl CH ), 2.30±
2 3
1
C H O calcdfor [M 1H] 313.17982, foundm/z
2
0
24
3
3
13.17992.
2.42 +m, 2H, CH2), 2.60±2.75 +m, 1H, CH2), 4.85 +t, 1H,
J4 Hz, CH), 6.0 +bs, 1H, OH), 6.95 +s, 2H, aromatic); HR-
1
MS: C H ClO calcdfor [M 1H] 319.10955, foundm/z
319.10953.
1.1.8. 6-Cycloheptyl-4-hydroxy-3-mesityl-2H-pyran-2-one
7c). Yield: 54%; mp 216±2188C. H NMR +200 MHz,
1
8
19
3
1
ꢀ
CDCl ) d 1.4±1.9 +m, 9H, CH ), 1.9±2.1 +m, 2H, CH ),
3
2
2
2
3
.1 +s, 6H, mesityl CH ), 2.1±2.2 +m, 1H, CH ), 2.3 +s,
3 2
1.2.5. 4-Hydroxy-3-mesityl-6-methyl-1-oxaspiro[4.4]nona-
3,6-dien-2-one ꢀ12a). White solid, mp 214±2168C; H
1
H, mesityl CH ), 2.6 +m, 1H, CH-CCH), 5.95 +s, 1H,
3
HCC), 6.95 +s, 2H, aromatic); HR-MS: C H O calcd
NMR +400 MHz, CDCl ) d1.66 + d, J 0.8Hz, 3H, H10),
2
1
26
3
3
1
for [M1H] 327.19547, foundm/z 327.19533.
2.11+s, 3H) and2.14 +s, 3H) H7' andH8', 2.22±2.32 +m, 4H,
H9', H9a), 2.36±2.61 +m, 3H, H9b, H8), 5.85±5.9 +m, 1H,
1
3
H7), 6.66 +s, 2H, H3', H5'), enol-OH not observed.
NMR +100 MHz, 80% CDCl 1 20% d6-DMSO) d 11.46
C
1.2. General procedure for the reaction of ketene 6with
cycloalkanones
3
+C10), 19.79 and20.19 +C7', C8'), 21.09 +C9'), 30.02 +C8),
33.16 +C9), 95.69 +C5), 101.48 +C3), 124.42 +C1'), 128.17
In a typical procedure, cycloalkanone 10 +40 mmol)
dissolved in 10 ml abs. xylene was added dropwise at
and128.19 +C3', C5'), 134.46 +C7), 136.03+C6), 138.16,
138.26 and138.30 +C2', C4', C6'), 172.76 +C2), 175.26
+C4). HR-MS: C H O calcdfor [M 1H] 285.14852,
1
208C to a solution of 2-+chlorocarbonyl)-2-mesitylketene 6
8.80g, 40 mmol) in 80 ml abs. xylene. The reaction mixture
1
8
20
3
+
foundm/z 285.14849.
was then heatedto re¯ux for 8h. The precipitate +spiro-
tetronic acid 12) obtainedupon cooling was recrystallised
from toluene/cyclohexane +3:1). Pyrone 11 couldbe isolated
after evaporation of xylene andsubsequent ¯ash chroma-
tography of the residue with toluene/acetone.
1.2.6. 4-Hydroxy-3-mesityl-6-methyl-1-oxaspiro[4.5]deca-
3,6-dien-2-one ꢀ12b). White solid, mp 223±2258C; H
1
NMR +200 MHz, CDCl ) d 1.60 +s, 3H, CH ), 1.70±1.90
3
3
+m, 3H, CH ), 2.05 +s, 3H, mesityl CH ), 2.08 +s, 3H, mesityl
2
3
CH ), 1.90±2.15 +m, 3H, CH ), 2.24 +s, 3H, mesityl CH ),
2
3
3
When the reaction was conducted neat, puri®cation was
performedby ¯ash chromatography +vi de supra).
5.90 +m, 1H, CHCCH ), 6.82 +s, 2H, aromatic); HR-MS:
3
1
C H O calcdfor [M 1H] 299.16417, foundm/z
1
9
22
3
299.16409.
1.2.1. 4-Hydroxy-3-mesityl-7-methyl-6,7-dihydrocyclo-
penta[b]pyran-2ꢀ5H)-one ꢀ11a). Brown solid, mp 216±
1.2.7. 6-Ethyl-4-hydroxy-3-mesityl-1-oxaspiro[4.5]deca-
3,6-dien-2-one ꢀ12c). White solid, mp 255±2578C;
1
1
2
188C; H NMR +200 MHz, CDCl ) d 1.34 +d, 3H, J
H
3
7
CH ), 2.14 +s, 3H, mesityl CH ), 2.35 +s, 3H, mesityl CH ),
.5 Hz, CH ), 1.67±1.85 +m, 2H, CH ), 2.12 +s, 3H, mesityl
NMR +200 MHz, CDCl ) d 1.00 +t, 3H, J 7.5Hz, CH ),
3
2
3
3
1.75±1.95 +m, 6H, CH ), 2.00 +s, 3H, mesityl CH ), 2.04 +s,
2 3
3
3
3
2
7
2
.7 +m, 2H, CH ), 3.1±3.35 +m, 1H, CH), 5.75 +bs, 1H, OH),
2
3H, mesityl CH ), 2.0±2.18 +m, 3H, CH ), 2.22 +s, 3H,
3 2
1
.0 +s, 2H, aromatic); HR-MS: C H O calcdfor [M 1H]
3
mesityl CH ), 5.90 +m, 1H, CHCCH ), 6.80 +s, 2H,
1
8
20
3
3
1
85.14852, foundm/z 285.14849.
aromatic); HR-MS: C H O calcdfor [M 1H]
20 24 3
313.17982, foundm/z 313.17981.
1
2
.2.2. 4-Hydroxy-3-mesityl-8-methyl-5,6,7,8-tetrahydro-
H-chromen-2-one ꢀ11b). White solid, mp 123±1258C; H
1
1.2.8. 6-tert-Butyl-4-hydroxy-3-mesityl-1-oxaspiro[4.5]-
deca-3,6-dien-2-one ꢀ12d). White solid, mp 273±2758C;
H NMR +200 MHz, CD OD) d 1.20 +s, 9H, t-Bu), 1.70±
3
NMR +200 MHz, CDCl ) d 1.35 +d, 3H, J 7.5 Hz, CH ),
3
3
1
1
3
.50±2.05 +m, 6H, CH ), 2.12 +s, 3H, mesityl CH ), 2.13 +s,
2
3
H, mesityl CH ), 2.30 +s, 3H, mesityl CH ), 2.45 +dt, 2H,
3
2.0 +m, 4H, CH ), 2.0±2.25 +m, 2H, CH ), 2.15 +s, 3H,
2
3
2
J 7.5 Hz, J 3 Hz, CH ), 2.7±2.85 +m, 1H, CH), 5.75 +bs,
mesityl CH ), 2.25 +s, 3H, mesityl CH ), 2.28 +s, 3H, mesityl
3 3
2