Ethanethiol → (R)-S-Ethyl 2-(2,2-dimethyl-5-oxo-1,3-dioxolan-4-yl)ethanethioate

Participants

Reaction Conditions

Reaction Steps

To a stirring suspension of (R)-(−)-dimethyl-5-oxo-1,2-dioxolane-4-acetic acid (3.5 g, 20 mmol), and CH2Cl2 (40 mL), at 0° C., under N2, was added isovalerylchloroformate (2.9 mL, 22 mmol) dropwise over 5 minutes. The mixture was stirred at 0° C. for 10 minutes. Triethylamine (5.5 mL, 40 mmol) was added dropwise at 0° C. followed by the dropwise addition of ethanethiol (3.4 mL, 44 mmol). The pink mixture was stirred at 0° C. for 10 minutes. To the reaction was added Et2O (40 mL) and the mixture was filtered. The filtrate was washed with 1.0 N aqueous HCl (20 mL), 0.1 N aqueous NaOH (20 mL), H2O (20 mL) and brine (20 mL). The organic solution was evaporated to dryness under reduced pressure to obtain the desired thioester as a clear oil (3.4 g, 16 mmol, 82% yield). 1H NMR (400 MHz, CDCl3) δ 4.71-4.65 (m, 1H), 3.91-3.81 (m, 1H), 3.11-2.70 (m, 3H), 1.53 (s, 3H), 1.50 (s, 3H), 0.87-0.86 (m, 3H). LC/MS (10%-99% CH3CN (0.035% TFA)/H2O (0.05% TFA)), m/z: M+1 obs=219.4; tR=1.33 min.

Provenance & Evidence