4834
D. Murali et al. / Tetrahedron: Asymmetry 11 (2000) 4831–4834
References
1
2
3
. Brown, H. C.; Ayyangar, N. R.; Zweifel, G. J. Am. Chem. Soc. 1964, 86, 1071.
. Brown, H. C.; Murali, D.; Singaram, B. J. Organomet. Chem. 1999, 581, 116.
. For synthetic applications of such chiral diols, see: (a) Whitesell, J. K. Chem. Rev. 1989, 89, 1581; (b) Matteson,
D. S. Chem. Rev. 1989, 89, 1535; (c) Anderson, B. A.; Wulff, W. D.; Rahm, A. J. Am. Chem. Soc. 1993, 115,
4
4
602. For recent preparations, see: (d) Fan, Q.-H.; Yeung, C.-H.; Chan, A. S. C. Tetrahedron: Asymmetry 1997,
, 4041; (e) Kita, Y.; Nagatomi, Y.; Kitagawa, H.; Fujioka, H. Electron. Conf. Heterocycl. Chem. 1998, 42 (Chem.
Abstr., 131:336556d); (f) Kuwano, R.; Masaya, S.; Shirai, J.; Takahashi, M.; Ito, Y. Bull. Chem. Soc. Jpn. 2000,
3, 485.
7
4
5
. Stang, P. J.; Mangum, M. G. J. Am. Chem. Soc. 1975, 97, 1459.
. (a) Helmkamp, G. K.; Lucas, H. J. J. Am. Chem. Soc. 1952, 74, 951; (b) Lucas, H. J.; Garner, H. K. J. Am.
Chem. Soc. 1948, 70, 990.
6
. The ee of 5 was determined by capillary GC analysis (SPB-5 column at 145°C) of its MTPA ester.
d
13
7
. The procedure for 5 is typical: To a mixture of Ipc BH (5.72 g, 20 mmol), (+)-a-pinene of 92% ee (0.52 mL,
2
3
mmol) and THF (11.8 mL) stirred at −25°C was added dropwise (E)-2-methoxy-2-butene (1.72 g, 20 mmol) for
11
about 5 min. Stirring was continued at −25°C. After 20 hours B NMR showed a single peak at l 81.96 ppm,
corresponding to a trialkylborane. To the reaction mixture kept at −25°C, a 3N aq. NaOH solution (7.0 mL) was
added, followed by 30% aq. H O (7.0 mL). The mixture was slowly warmed to rt and stirred overnight. After
2
2
saturating the mixture with K CO , the organic layer was separated and the aqueous layer was extracted with
2
3
ether. The combined organic layers were dried over Na SO and fractionated using a Vigreux column to give pure
2
4
2
4
5
(
2R,3R)-3-methoxy-2-butanol at 68°C/100 mm of Hg (5, 1.5 g, 72%). [h] =−26.3 (neat). Lit. −26.2 (neat).
. The ee of 8 was determined by comparing its optical rotation [h] =+18.0 with the reported value ([h] =+20.1
D
24
5
D D
8
9
(
neat), for (+)-[2R,3S]-3-methoxy-2-butanol of 100% enantiomeric excess), as the GC separation of its MTPA
ester was unsuccessful.
. (a) Brown, H. C.; Jadhav, P. K.; Mandal, A. K. Tetrahedron 1981, 37, 3547 and references cited therein; (b)
Houk, K. N.; Rondan, N. G.; Wu, Y.-D.; Metz, J. T.; Paddon-Row, M. N. Tetrahedron 1984, 40, 2257.
1
0. Preparation of 10: To a solution of 5 (7.8 g, 75 mmol) in ether (150 mL) was added NEt (12.5 mL, 90 mmol)
3
and Me SiCl (11.4 mL, 90 mmol) at rt and the mixture was heated to reflux for 12 h. The precipitated solids were
3
filtered off and the filtrate was fractionated (145°C/750 mm of Hg) to give pure silyl ether 9 (11.0 g, 84% yield).
To a solution of 9 (8.8 g, 50 mmol) in CHCl (30 mL) was added Me SiI (13.5 g, 67.6 mmol). The mixture was
3
3
heated at 35°C for 12 hours. Methanol (6 mL) was added and stirred at room temp. for 2 h. The volatiles were
removed under reduced pressure and the residue was distilled. Pure (−)-[2R,3R]-butane-2,3-diol 10 was collected
24
at 100°C/30 mm of Hg. Yield 3.5 g (78%). [h]D −12.6 (neat).
1. Plattner, J. J.; Rapoport, H. J. Am. Chem. Soc. 1971, 93, 1758.
2. Determined by the GC analysis of its MTPA ester using a SPB-5 column at 220°C.
3. Brown, H. C.; Singaram, B. J. Org. Chem. 1984, 49, 945.
1
1
1
.
.