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C. Pichon et al. / Tetrahedron: Asymmetry 15 (2004) 1103–1111
20
D
90:10 fi 70:30), successively provided (+)-13 then (+)-9.
Compound (+)-13 was thus obtained as an oil in 78%
and 67% yield, respectively. ½a ¼ +75 (c 1, CHCl3),
obtained in 81% yield as an oil. ½a ¼ +9.1( c 1,
CHCl3), ee 99.9% (determined by GPC). 1H NMR
(CDCl3) d 1.80–1.90 (m, 1H), 2.03 (s, 3H), 2.10–2.17 (m,
2H), 2.34–2.43 (m, 1H), 2.95–3.04 (m, 1H), 3.28–3.36
(m, 1H), 4.21 (dd, 1H, J ¼ 11:3, 6.5 Hz), 4.27 (dd, 1H,
J ¼ 11:3, 7.3 Hz), 9.80 (br s, 1H); 13C NMR (CDCl3) d
20.7, 21.0, 21.5, 36.3, 39.3, 64.6, 171,2, 179.2; IR (m
cmꢀ1) 3390, 1740, 1702. Anal. Calcd for C8H12O4: C,
55.80; H, 7.02. Found: C, 55.66, H, 7.12. Lactone ())-18
20
D
98.2% ee [presumed identical to the ee of the precursor
1
())-4]. H NMR (CDCl3) d 2.75 (s, 1H), 2.87 (m, 1H),
3.47 (m, 2H), 3.69 (s, 1H), 6.20 (dd, 1H, J ¼ 2:9, 0.9 Hz),
6.25 (dd, 1H, J ¼ 2:9, 0.7 Hz), 7.18–7.34 (m, 6H), 7.42–
7.49 (m, 4H); 13C NMR (CDCl3) d 46.4, 55.8, 63.9, 76.8,
125.7, 126.5, 127.0, 128.0, 128.1, 137.0, 140.4, 145.8 et
145.8; IR (m cmꢀ1) 3200, 3008, 2975, 1610, 1420. Anal.
Calcd for C18H18O2: C, 81.17; H, 6.81. Found: C, 81.16,
H, 6.67.
was then obtained from (+)-17 [see preparation of
20
D
())-7] in 87% yield as an oil. ½a ¼ )62 (c 1.3, CHCl3),
1
99.9% ee (determined by GPC). H NMR (CDCl3) d
2.08–2.21(m, 2H), 2.37–2.45 (m, H1 ), 2.50–2.61(m,
1H), 3.08–3.14 (m, 1H), 3.16–3.22 (m, 1H), 4.23 (m, 1H),
4.36 (m, 1H); 13C NMR (CDCl3) d 23.4, 25.3, 34.3, 38.1,
74.1, 180.8; IR (m cmꢀ1) 2975, 2880, 1759.
4.10. (+)-(1S,4S)-(4-Hydroxydiphenylmethyl)cyclobut-2-
ene carboxylic acid, (+)-14
Oxidation of (+)-13 [see preparation of (+)-8] yielded
(+)-14 as an oil (86%). An analytical sample was
obtained by column chromatography on silica gel (C6H12/
4.13. (+)-(1R,2S)-(2-Hydroxymethylcyclobutyl)diphenyl-
methanol, (+)-19
20
Et2O, 90:10 fi 75:25). ½a ¼ +170 (c 1 , CHCl), ee
3
D
98.2% [presumed identical to the ee of the precursor ())-
Reaction of ())-18 with PhMgBr [see preparation of (+)-
9] led to (+)-19 as white crystals in 93% yield. Mp 136–
1
4]. H NMR (CDCl3) d 1.36 (s, 1H), 3.55 (m, 1H), 4.20
20
(m, 1H), 6.19 (ddd, 1H, J ¼ 2:8, 1.2, 0.7 Hz), 7.18–7.33
(m, 6H), 7.41–7.44 (m, 4H); 13C NMR (CDCl3) d 46.7,
55.3, 77.0, 125.8, 126.1, 127.2, 128.2, 137.5, 139.0, 144.8,
145.3, 178.1; IR (m cmꢀ1) 3400, 1708, 1420,1166. Anal.
Calcd for C18H16O3, 0.2H2O: C, 76.15; H, 5.82. Found:
C, 76.40, H, 5.78.
137 °C (C6H12); ½a ¼ +72 (c 1 , CHCl), 99.9% ee
3
D
[presumed identical to the ee of the precursor ())-18]. 1H
NMR (CDCl3) d 1.66–1.82 (2m, 2H), 2.01 (m, 1H,
J ¼ 11:2, 8.9 Hz), 2.20 (br s, 1H), 2.33 (m, 1H, J ¼ 9:9,
1.1 Hz), 2.76 (m, 1H), 3.53 (dd, 1H, J ¼ 11:9, 3.0 Hz),
3.63 (m, 2H), 4.77 (br s 1H), 7.15 (m, 1H), 7.20–7.26 (m,
4H), 7.30–7.35 (m, 4H), 7.51–7.54 (m, 1H); 13C NMR
(CDCl3) d. 19.9, 21.3, 40.0, 45.7, 62.4, 125.7, 126.1,
126.3, 126.6, 127.8, 128; IR (m cmꢀ1) 3285, 2970, 2920,
2875, 1410, 1150. Anal. Calcd for C18H20O2: C, 80.56;
H, 7.56. Found: C, 80.69, H, 7.64.
4.11. (1S,4S)-[4-(Hydroxydiphenylmethyl)cyclobut-2-
enyl]diphenylmethanol, (+)-15
Reaction of (+)-14 with CH2N2 [see preparation of (+)-
10b] led to the corresponding methyl ester as a yellow oil
20
D
(quant). ½a ¼ +176 (c 1 , CHC3l), 98.2% ee [presumed
4.14. (+)-(1R,2S)-2-Acetoxymethylcyclobutane carbox-
ylic acid 9H-fluoren-9-yl ester, (+)-20a
identical to the ee of the precursor ())-4]. 1H NMR
(CDCl3) d 2.48 (s, 2H), 3.54 (m, 1H), 3.57 (s, 3H), 4.19
(m, 1H), 6.19 (dt, 1H, J ¼ 2:9, 1.0 Hz), 6.28 (ddd, 1H,
J ¼ 2:9, 1.0, 0.5 Hz), 7.19–7.33 (m, 6H), 7.41–7.46 (m,
4H); 13C NMR (CDCl3) d 46.7, 52.1, 55.3, 77.0, 125.8,
126.1, 127.2, 128.2, 137.5, 139.0, 144.8, 145.3, 178.1; IR
(m cmꢀ1) 3220, 1740, 1420, 1320, 1160. Anal. Calcd for
C19H18O3: C, 77.53; H, 6.16. Found: C, 77.38, H, 6.12.
Reaction of this ester with PhMgBr [see preparation of
Esterification of (+)-17 with fluorenol [see preparation
of ())-10a] provided compound ())-20a as a paste in
20
82% yield. ½a ¼ +16 (c 1, CHCl3), 99.9% ee [presumed
D
identical to the ee of the precursor (+)-16]. H NMR
1
(CDCl3) d 1.90 (s, 3H), 1.91 (m, 1H), 2.16 (m, 2H), 2.47
(m, 1H), 2.97 (m, 1H), 3.39 (m, 1H), 4.26 (d, 2H,
J ¼ 6:8 Hz), 6.78 (s, 1H), 7.30 (dd, 1H, J ¼ 7:5, 2.5 Hz),
7.41(td, 2H, J ¼ 7:5, 0.6 Hz), 7.57 (td, 2H, J ¼ 7:7,
0.6 Hz), 7.66 (d, 2H, J ¼ 7:5 Hz); 13C NMR (CDCl3) d
20.6, 21.2, 21.5, 36.1, 39.4, 64.5, 75.2, 119.8, 125.9,
126.0, 127.7 127.8, 129.3, 140.9, 141.8, 141.9, 170.8,
174.0; IR (m cmꢀ1) 3007, 2948, 1736, 1731, 1452, 1365,
1240, 1170, 1039, 762, 742. Anal. Calcd for C21H20O4: C,
74.98; H, 5.99. Found: C, 75.16, H, 6.17.
(+)-9] yielded (+)-15 as a white solid in 85% yield. Mp
20
D
135–140 °C (dec); ½a ¼ +76 (c 1, CHCl3), ee 98.2%
1
[presumed identical to the ee of the precursor ())-4]. H
NMR (CDCl3) d 3.59 (s, 2H), 5.52 (br s, 2H), 6.13 (s,
2H), 6.76–6.79 (m, 4H), 6.90 (tt, 2H, J ¼ 7:4, 1.1 Hz),
7.14–7.41 (m, 14H); 13C NMR (CDCl3) d 50.0, 78.2,0,
125.8, 126.1, 127.6, 127.7, 128.2, 128.3, 139.0, 144.7,
145.5; IR (m cmꢀ1) 3215, 3006, 1610, 1332. Anal. Calcd
for C30H26O2: C, 86.09; H, 6.26. Found: C, 86.14, H,
6.31.
4.15. ())-(1R,2S)-2-Acetoxymethylcyclobutane carbox-
ylic acid methyl ester, (+)-20b
4.12. (1R,5S)-3-Oxabicyclo[3.2.0]hept-6-en-2-one,
())-1815
Esterification of (+)-17 with diazomethane [see prepa-
ration of (+)-10b] quantitatively led to compound (+)-
20
D
20b as a yellow oil. ½a ¼ +38 (c 1 , CHC3l), 99.9% ee
Compound (+)-164 was oxidized into acid (+)-17 with
JonesÕ reagent [see preparation of (+)-8]. This acid was
[presumed identical to the ee of the precursor (+)-16]. 1H
NMR (CDCl3) d 1.77–1.86 (m, 1H), 2.02 (s, 3H), 2.05–