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10443
4.2.6. 2-Hydroxymethyl-thiobutyric acid S-tert-butyl
1
tography (AcOEt/hexane 1/2) to provide 8 as a colorless oil
(6.5 mg, 0.0396 mmol, 42% yield) and 8 (15.1 mg,
0.0542 mmol, 58% recovery): H NMR (CDCl3) d 1.24
ester. H NMR (CDCl3) d 0.97 (t, 3H, J¼7.2 Hz), 1.48 (s,
1
9H), 1.52–1.78 (m, 2H), 2.00 (brs), 2.55–2.65 (m, 1H),
3.71 (dd, 1H, J¼4.1, 11.1 Hz), 3.78 (dd, 1H, J¼7.0,
11.1 Hz); 13C NMR (CDCl3) d 11.6, 22.4, 29.8, 48.3,
57.8, 63.3. 203.9; IR (neat) 3407, 2966, 1681, 1456, 1364,
945 cm21; MS m/z 190 (Mþ). Anal. calcd for C9H18O2S: C,
56.80; H, 9.53; N, 0.00. Found: C, 57.05; H, 9.32; N, 0.00;
[a]2D7¼22.5 (45% ee, c 1.25, EtOH); HPLC (Daicel
Chiralpak ADH, hexane/i-PrOH¼100/1, flow rate¼1.0
mL/min) assumed R isomer: tR¼27.5 min (major), assumed
S isomer: tR¼40.0 min (minor).
(d, 3H, J¼7.1 Hz), 2.35 (brs), 3.68 (ddq, 1H, J¼4.3, 7.0,
7.1 Hz), 3.80 (dd, 1H, J¼4.3, 11.1 Hz), 3.94 (dd, 1H, J¼7.0,
11.1 Hz), 7.48 (dd, 2H, J¼7.3, 8.5 Hz), 7.58 (t, 1H, J¼
7.3 Hz), 7.97 (d, 2H, J¼8.5 Hz); 13C NMR (CDCl3) d 14.5,
42.9, 64.5, 128.4, 128.7, 133.3, 136.1, 204.4; IR (neat) 3415,
2936, 1681, 1448, 974, 704 cm21; MS m/z 164 (Mþ). Anal.
calcd for C10H12O2: C, 73.15; H, 7.37; N, 0.00. Found: C,
72.87; H, 7.40; N, 0.00; [a]2D4¼242.1 (c 0.28, EtOH)
(.99% ee); HPLC (Daicel Chiralpak AD-H, hexane/
i-PrOH¼19/1, flow rate¼1.0 mL/min) R isomer: tR¼
20.0 min (major), S isomer: tR¼17.2 min (minor).
4.2.7. 3-Hydroxy-2-methyl-thiopropionic acid S-isopro-
pyl ester. 1H NMR (CDCl3) d 1.20 (d, 3H, J¼7.1 Hz), 1.31
(d, 3H, J¼6.8 Hz), 1.32 (d, 3H, J¼7.1 Hz), 2.19 (brs), 2.82
(ddq, 1H, J¼4.6, 7.1, 7.1 Hz), 3.67 (qq, 1H, J¼6.8, 7.1 Hz),
3.69 (dd, 1H, J¼4.6, 11.1 Hz), 3.78 (dd, 1H, J¼7.1,
11.1 Hz); 13C NMR (CDCl3) d 14.2, 22.9, 22.9, 34.5,
50.4, 64.8, 203.5; IR (neat) 3414, 2969, 1679, 1454, 1054,
966 cm21; MS m/z 162 (Mþ). Anal. calcd for C7H14O2S: C,
51.82; H, 8.70. Found: C, 51.76; H, 8.51; [a]2D7¼26.7 (c
0.19, EtOH) (23% ee); HPLC (Daicel Chiralpak AD-H,
hexane/i-PrOH¼100/1, flow rate¼1.0 mL/min) assumed R
isomer: tR¼37.1 min (major), assumed S isomer: tR¼
41.8 min (minor).
4.3.3. 3-Hydroxy-2-methylpropionic acid methyl ester
(10). To a solution of sodium methoxide (8.8 mg,
0.163 mmol) in MeOH (0.07 mL) was added 9 (51% ee,
18.2 mg, 0.103 mmol) at room temperature. The mixture
was stirred for 100 min and quenched by addition of
saturated NH4Cl aqueous solution. Methylene chloride was
then added, the layers were separated, and the aqueous
phase was extracted with methylene chloride five times. The
combined organic layers were dried over Na2SO4, the
solvent was removed under reduced pressure, and dried in
vacuo to provide 10 as a colorless oil (8.1 mg, 0.0686 mmol,
1
67% yield): H NMR (CDCl3) d 1.19 (d, 3H, J¼7.3 Hz),
4.3. Determination of absolute configurations
2.24 (brs), 2.62–2.76 (m, 1H), 3.66–3.78 (m, 2H), 3.73 (s,
3H); 13C NMR (CDCl3) d 13.4, 41.6, 51.8, 64.6, 176.1;
[a]1D7¼211.1 (c 0.41, MeOH).
4.3.1. (R)-3-(tert-Butyldimethylsilyloxy)-2-methyl-1-
phenylpropan-1-one (7). To a solution of 6 (142 mg,
0.542 mmol) in THF (2.2 mL) at 2408C was added a
PhLi solution (1.06 M cyclohexane/ether sol., 0.61 mL,
0.650 mmol) over 10 min. The mixture was stirred for
10 min and quenched by addition of saturated NH4Cl
aqueous solution. Ether was then added, the layers were
separated, and the aqueous phase was extracted with ether
twice. The combined organic layers were dried over MgSO4
and the solvent was removed under reduced pressure. The
product was purified by silica gel chromatography (AcOEt/
hexane 1/6) to provide 7 as a colorless oil (50.2 mg,
0.180 mmol, 33% yield) and 6 (95.1 mg, 0.364 mmol, 67%
recovery): 1H NMR (CDCl3) d 20.04 (s, 3H), 0.00 (s, 3H),
0.81 (s, 9H), 1.17 (d, 3H, J¼6.6 Hz), 3.68 (dd, 1H, J¼6.1,
9.0 Hz), 3.72 (ddq, 1H, J¼6.1, 6.6, 6.6 Hz), 3.92 (dd, 1H,
J¼6.6, 9.0 Hz), 7.42–7.49 (m, 2H), 7.51–7.58 (m, 1H),
7.94–8.00 (m, 2H); 13C NMR (CDCl3) d 25.6, 25.6, 14.2,
18.2, 25.8, 43.6, 66.0, 128.4, 128.5, 132.8, 137.3, 203.7; IR
References
1. For reviews on asymmetric aldol reactions, see:
(a) Machajewski, T. D.; Wong, C.-H. Angew. Chem., Int.
Ed. 2000, 39, 1352–1374. (b) Carreira, E. M. Comprehensive
Asymmetric Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto,
H., Eds.; Springer: Heidelberg, 1999; Vol. 3, pp 998–1065.
(c) Mahrwald, R. Chem. Rev. 1999, 99, 1095–1120.
¨
(d) Groger, H.; Vogl, E. M.; Shibasaki, M. Chem. Eur. J.
1998, 4, 1137–1141. (e) Nelson, S. G. Tetrahedron:
Asymmery 1998, 9, 357–389.
2. The first report of Mukaiyama aldol reactions, see:
Mukaiyama, T.; Narasaka, K.; Banno, K. Chem. Lett. 1973,
1011–1014.
3. Coates, R. M.; Denmark, S. M. In Handbook of Reagents for
Organic Synthesis; Paquette, L. A., Ed.; Wiley: Chichester,
1999; pp 394–399.
(neat) 2929, 2856, 1684, 1257, 1217, 1099, 837, 777 cm21
;
MS m/z 278 (Mþ). Anal. calcd for C16H26O2Si: C, 69.01; H,
9.41. Found: C, 68.85; H, 9.27; [a]2D6¼231.9 (c 1.44, EtOH).
4. Fujii, M.; Sato, Y.; Aida, T.; Yoshihara, M. Chem. Express
1992, 7, 309–312.
4.3.2. (R)-3-Hydroxy-2-methyl-1-phenylpropan-1-one
(8). To a solution of 7 (26.1 mg, 0.0937 mmol) in THF
(1.9 mL) was added hydrogen fluoride–pyridine complex at
08C in several portions until a suitable amount of desired
product appeared on TLC. After 20 min, the solution was
diluted with ether and neutralized with saturated sodium
hydrogen carbonate aqueous solution. The layers were
separated and the aqueous layer was extracted with ether.
The combined organic layers were washed with brine, dried
over Na2SO4, and the solvent was removed under reduced
pressure. The product was purified by silica gel chroma-
5. Kuwano, R.; Miyazaki, H.; Ito, Y. Chem. Commun. 1998,
71–72.
6. Trioxane was used as formaldehyde surrogate. Mukaiyama,
T.; Banno, K.; Narasaka, K. J. Am. Chem. Soc. 1974, 96,
7503–7509.
7. For hydroxymethylation of a silicon enolate in aqueous
media without any catalysts, see: Lubineau, A.; Meyer, E.
Tetrahedron 1988, 44, 6065–6070.
8. For reviews on organic reactions in aqueous media, see: (a). In
Organic Synthesis in Water; Grieco, P. A., Ed.; Blackie
Academic and Professional: London, 1998. (b) Li, C.-J.; Chan,