tert-Butyl methyl ether → (1S)-2-Methyl-1-methylthiocarbonyloxypropyl 2-methylpropanoate

Participants

Reaction Steps

A mixture of 990 mL methyl-tert-butylether (MTBE) and 10 mL water was stirred until a clear solution was obtained (ca. 5 hrs). To this solution was added 2-methyl-1-methylthiocarbonyloxypropyl 2-methylpropanoate (2b) (50 g) and PLE/MPEG (50 mg/1 g, 7.5 g). The resulting suspension was stirred at room temperature. The reaction was monitored by 1H-NMR using a chiral solvating agent. After 1H-NMR showed only one enantiomer remained in the reaction mixture (ca. 48 hrs), the reaction was quenched by filtration through a pad of CELITE® 545. The supernatant was washed with water, aqueous sodium bicarbonate (NaHCO3) and brine, and dried over anhydrous sodium sulfate (Na2SO4). After rotary evaporation, the title compound (12) was obtained with 70% yield. The enantiomeric excess of the S-enantiomer was 100% e.e. as determined by chiral HPLC. 1H-NMR (CDCl3): δ 0.96 (d, J=6.8 Hz, 6H), 1.16 (d, J=6.8 Hz, 3H), 1.17 (d, J=6.8 Hz, 3H), 1.98-2.07 (m, 1H), 2.32 (s, 3H), 2.56 (septet, J=7.2 Hz, 1H), 6.67 (d, J=5.6 Hz, 1H) ppm. 1H-NMR with chiral solvating agent (R)-(−)-2,2,2-trifluoro-1-(9-anthryl)ethanol: δ 0.98 (d, J=6.8 Hz, 3H), 0.99 (d, J=6.8 Hz, 3H), 1.19 (d, J=7.2 Hz, 1.5H), 1.19 (d, J=6.8 Hz, 1.5H), 1.20 (d, J=6.8 Hz, 1.5H), 1.20 (d, J=7.2 Hz, 1.5H), 2.01-2.09 (m, 1H), 2.34 1(s, 1.5H), 2.44 (s, 1.5H), 2.59 (septet, J=7.2 Hz, 0.5H), 2.59 (septet, J=6.8 Hz, 0.5H), 6.70 (d, J=5.6 Hz, 0.5H), 6.70 (d, J=5.2 Hz, 0.5H) ppm.

Provenance & Evidence