Acetic Acid → HCID 131719064, compound

Participants

Reaction Steps

To a suspension of KH (19.3 g, 25% suspension in oil, mmol) in tetrahydrofuran (100 mL) at 0° C. was slowly added (over 25 min) a solution of Cbz-D-Cha-Pro-OH (16.8 g, 41.7 mmol) in tetrahydrofuran (50 mL). During this addition period the internal temperature was monitored and maintained at less than 10° C. To this solution was then slowly added a solution of methyl iodide (5 mL, 80 mmol) and 18-crown-6 (661 mg, 2.5 mmol), again maintaining the internal temperature below 10° C. After 2 h acetic acid (10 mL) was added dropwise, followed by water (10 mL). The solution was then poured into cold water and the pH was adjusted to 9 with 2N NaOH. The aqueous base was washed twice with diethyl ether and then acidified to pH 2 with conc. HCl and extracted four times with chloroform. The chloroform extracts were combined, dried over Na2SO4, filtered and concentrated in vacuo to afford 15.7 g (90%) of a pale yellow solid.

Provenance & Evidence