methyl (2R)-2-hydroxybutanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of methanesulfonic acid chloride (5.33 g, 46.5 mmol, 1.1 equiv.) in dichloromethane (50 ml, 11 vol.) cooled to 0-5° C. is added over a period of 30 min. a mixture of methyl-(R)-2-hydroxybutyrate (5.1 g, 43.2 mmol, 1 equiv.) and triethylamine (4.7 g, 46.5 mmol, 1.1 equiv.) in dichloromethane (25 ml). When conversion is complete (TLC: methylcyclohexane/ethyl acetate=1/1 (v/v), dying with molybdatophosphoric acid; Rf=0.5), the mixture is allowed to warm to room temperature and 50 ml of water is added. The two resulting layers are separated and the organic layer is washed with 50 ml of water. The organic layer is dried over sodium carbonate and concentrated under reduced pressure to afford methyl-(R)-2-methanesulfonyloxybutyrate (IIg) as yellow oil (8.5 g, 43.2 mmol, 100%) is added over a period of 30 min. The two resulting layers are separated the organic layer is washed with 50 ml of water The organic layer is dried over sodium carbonate concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The title compound was prepared following the same protocol as described in Step 1, Example 42, using the (R)-methyl 2-hydroxybutanoate instead of the (S)-methyl 2-hydroxypropanoate and the 4-chloro-3-methylphenol instead of the m-cresol.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The title compound was prepared following the same protocol as described in Step 1, Example 42, using the (R)-methyl 2-hydroxybutanoate instead of the (S)-methyl 2-hydroxypropanoate and the 2-chloro-5-methylphenol instead of the m-cresol.