A. M. Bernard et al. / Tetrahedron 60 (2004) 449–457
455
(m, 1H), 3.41 (d, 1H, J¼11.4 Hz), 3.82 (d, 1H, J¼11.4 Hz),
6.73–7.52 (m, 3H). 13C NMR (CDCl3) d:16.5, 19.7, 35.5,
45.1, 69.4, 69.6, 116.6, 118.8, 127.7, 128.6, 129.5, 152.4,
154.3. IR (neat, cm21): 3340. MS m/z: 226 (Mþþ2 (9)), 224
(Mþ(26)), 196 (100), 181 (66), 155 (95), 128 (11). Anal.
Calcd for C12H13O2Cl: C, 64.15; H, 5.83. Found: C, 64.35;
H, 5.74.
cm21): 1170, 1350. Anal. Calcd for C20H22O5S: C, 64.15;
H, 5.92; S, 8.56. Found: C, 64.22; H, 5.78; S, 8.48.
4.5.2. 2-(3,7-Dimethyl-2H-chromen-4-yl)ethyl 4-methyl-
1
benzenesulfonate (5d). Yellow oil. Yield 80%. H NMR
(CDCl3) d: 1.72 (s, 3H), 2.25 (s, 3H), 2.41 (s, 3H), 2.83 (t,
2H, J¼7.2 Hz), 4.05 (t, 2H, J¼7.2 Hz), 4.49 (s, 2H), 6.57–
7.73 (m, 7H). 13C NMR (CDCl3) d: 15.7, 21.1, 21.6, 26.5,
68.2, 69.3, 116.4, 120.1, 121.6, 121.9, 122.0, 127.8, 128.0,
129.7, 132.9, 138.3, 144.7, 153.3. IR (neat, cm21): 1180,
1370. Anal. Calcd for C20H22O4S: C, 67.02; H, 6.19; S,
8.94. Found: C, 67.12; H, 6.28; S, 8.88.
4.4.4. 2a,6-Dimethyl-1,2,2a,3-tetrahydro-8bH-cyclo-
buta[c]chromen-8b-ol (4d). Yellow oil. Yield 30%. 1H
NMR (CDCl3) d: 1.20 (s, 3H), 1.42 (m, 1H), 1.75 (m, 1H),
1.94 (br s, 1H), 2.00 (m, 1H), 2.30 (s, 3H), 2.44 (m, 1H),
3.43 (d, 1H, J¼11.4 Hz), 3.79 (d, 1H, J¼11.4 Hz), 6.71 (s,
1H), 6.84 (d, J¼8.1 Hz), 7.41 (d, 1H, J¼8.1 Hz). 13C NMR
(CDCl3) d: 16,6, 19.8, 21.1, 35.4, 45.2, 69.2, 69.4, 117.4,
123.1, 126.1, 127.7, 138.6, 153.6. IR (neat, cm21): 3400.
MS m/z: 204 (Mþ(13)), 189 (5), 176 (100), 161 (61), 135
(97). Anal. Calcd for C13H16O2: C, 76.44; H, 7.90. Found:
C, 76.34; H, 7.76.
4.5.3. 2-(2,3-Methyl-2H-chromen-4-yl)ethyl 4-methyl-
1
benzenesulfonate (5f). Yellow oil. Yield 35%. H NMR
(CDCl3) d: 1.24 (d, 3H, J¼6.3 Hz), 1.76 (s, 3H), 2.41 (s,
3H), 2.85 (t, 2H, J¼7.5 Hz), 3.96–4.11 (m, 2H), 4.62 (q,
1H, J¼6.3 Hz), 6.75–7.08 (m, 4H), 7.28 (d, 2H, J¼8.4 Hz),
7.73 (d, 2H, J¼8.4 Hz). 13C NMR (CDCl3) d: 16.0, 18.2,
21.6, 26.6, 29.6, 68.1, 74.8, 116.7, 120.6, 120.9, 122.0,
127.7, 128.1, 129.7, 132.9, 133.4, 144.7, 151.6. IR (neat,
cm21) 1200, 1380. Anal. Calcd for C20H22O4S: C, 67.02; H,
6.19; S, 8.94. Found: C, 67.22; H, 5.98; S, 8.78.
4.4.5. 2a,8-Dimethyl-1,20,2a,3-tetrahydro-8bH-cyclo-
1
buta[c]chromen-8b-ol (4d ). Yellow oil. Yield 40%. H
NMR (CDCl3) d: 1.23 (s, 3H), 1.50, (m, 1H), 1.73 (m, 1H),
1.74 (br s, 1H), 2.25 (m, 1H), 2.43 (s, 3H), 2.51 (m, 1H),
3.56 (d, 1H, J¼11.1 Hz), 3.82 (d, 1H, J¼11.1 Hz), 6.73 (d,
1H, J¼8.4 Hz), 6.80 (d, 1H, J¼7.2 Hz), 7.07 (unresolved
dd, 1H). 13C NMR (CDCl3) d: 17.1, 20.8, 21.2, 34.1, 44.5,
69.1, 69.8, 115.1, 124.6, 125.1, 128.2, 139.5, 154.3. IR
(neat, cm21): 3450. MS m/z: 204 (Mþ(25)), 189 (2), 176
(79), 161 (73), 135 (100). Anal. Calcd for C13H16O2: C,
76.44; H, 7.90. Found: C, 76.36; H, 7.78.
4.5.4. 2-(6-Methoxy-2-methyl-3,4-dihydro-1-naphthal-
enyl)ethyl 4-methylbenzenesulfonate (5i). Yellow oil.
1
Yield 90%. H NMR (CDCl3) d: 1.84 (s, 3H), 2.15 (t, 2H,
J¼7.8 Hz), 2.42 (s, 3H), 2.63 (t, 2H, J¼7.8 Hz), 2.88 (t, 2H,
J¼7.8 Hz), 3.77 (s, 3H), 4.04 (t, 2H, J¼7.8 Hz), 6.61–6.64
(m, 2H), 6.94 (d, 1H, J¼8.4 Hz), 7.29 (d, 2H, J¼8.4 Hz),
7.75 (d, 2H, J¼8.4 Hz). 13C NMR (CDCl3) d: 20.1, 21.5,
27.8, 28.6, 30.4, 55.2, 68.7, 110.8, 113.6, 122.8, 123.1,
127.8, 129.7, 133.2, 133.6, 137.4, 144.6, 157.7. IR (neat,
cm21): 1180, 1360. Anal. Calcd for C21H24O4S: C, 67.72;
H, 6.49; S, 8.61. Found: C, 67.52; H, 6.78; S, 8.48.
4.4.6. 2a,3-Dimethyl-1,2,2a,3-tetrahydro-8bH-cyclo-
buta[c]chromen-8b-ol (R pS pR p-4f). White crystals, mp
98 8C. Yield 30%. 1H NMR (CDCl3) d:1.24 (s, 3H), 1.25 (d,
3H, J¼6.6 Hz)), 1.30–1.37 (m, 1H), 1.68 (m, 1H), 1.94–
2.02 (m, 2H, one D2O exchangeable), 2.37–2.48 (m, 1H)
3.54 (q, 1H, J¼6.6 Hz), 6.89–7.50 (m, 4H). 13C NMR
(CDCl3) d: 15.6, 17.0, 17.5, 35.1, 49.0, 69.8, 73.8, 117.1,
121.8, 127.7, 128.4, 129.0, 153.5. IR (neat, cm21): 3400.
MS m/z: 204 (Mþ(10)), 186 (8), 176 (32), 161 (100), 121
(65). Anal. Calcd for C13H16O2: C, 76.44; H, 7.90. Found:
C, 76.52; H, 7.78.
Spectral data of 1f, 2f, 3f0, 4f00, enantiomerically enriched,
were identical with those of the corresponding racemic
samples.
4.5.5. 1-(2-Cyclopropylidene-1-methylpropoxy)benzene
(1f). [a]1D9¼226.12 (c¼2.68, CHCl3).
4.5.6. 2-Methyl-2-(1-phenoxyethyl)cyclobutanone. (3f0).
[a]2D0¼219.76 (c¼0.753, CHCl3).
4.5. General procedure for the preparation of chromenes
5b, d, f, i
4.5.7. 2a,3-Dimethyl-1,2,2a,3-tetrahydro-8bH-cyclo-
buta[c]chromen-8b-ol (4f00). [a]D19¼þ20.19 (c¼3.07,
CHCl3).
A stirred solution of cyclobutanone 3 (2.7 mmol) and
p-toluenesulfonic acid (0.46 g, 2.7 mmol,) in dry benzene
(10 mL) was refluxed for 30 min in a Dean–Stark
apparatus. The reaction mixture was diluted with CH2Cl2
and washed with 10% NaHCO3 and brine, dried (Na2SO4)
and evaporated to remove the solvent. The residue was
chromatographed on silica gel with diethyl ether/light
petroleum (1:1).
4.5.8. (R)-(1)-3-phenoxy-2-butanone (6). A stirred sol-
ution of (R)-2-phenoxypropionic acid (1.3 g, 7.8 mmol) in
dry THF (60 mL) was cooled to 0 8C (ice bath) and treated
rapidly (ca. 20 s) with 1.6 M methyllithium in ether
(19.4 mL, 31 mmol,). After 2 h at 0 8C, freshly distilled
Me3SiCl (20 mL, 15.6 mmol) was rapidly added while
stirring continued. The ice bath was removed and the
reaction mixture allowed to reach room temperature. 1 N
HCl (58 mL) was added, and the resulting two phase
system was stirred at room temperature for 0.5 h. The
mixture was then extracted with diethyl ether and the
ethereal layers were washed with brine and dried with
Na2SO4. Removal of the solvent in vacuo gave the crude
4.5.1. 2-(6-Methoxy-3-methyl-2H-chromen-4-yl)ethyl
4-methylbenzenesulfonate (5b). Yellow oil. Yield 86%.
1H NMR (CDCl3) d: 1.73 (s, 3H), 2.39 (s, 3H), 2.82 (t, 2H,
J¼7.5 Hz), 3.72 (s, 3H), 4.05 (t, 2H, J¼7.5 Hz), 4.44 (s,
2H), 6.81–7.64 (m, 7H). 13C NMR (CDCl3) d: 15.8, 21.4,
26.5, 55.6, 68.0, 69.1, 108.4, 112.3, 116.0, 121.6, 123.6,
127.5, 129.7, 130.3, 132.7, 144.6, 147.1, 154.1. IR (neat,