Triethylamine → Boc-Tyr-OMe

Participants

Reaction Steps

L-tyrosine methyl ester hydrochloride 2 (104.3 g, 0.45 mol) and di-t-butylcarbonate (DBC, 98.2 g, 0.45 mol) were suspended in toluene (521.3 g), and triethylamine (50.1 g, 0.495 mol) was added dropwise thereto at 20° C. over 1.5 hrs. After further keeping at 20° C. for 4 hrs, the reaction mass was washed with 5% hydrochloric acid (328.1 g) and 5% aqueous sodium bicarbonate (378.1 g). The toluene solution thus obtained was dried over suitable amount of magnesium sulfate and then concentrated to about a half of the volume under reduced pressure. To the concentrate was added dropwise n-hexane (329.5 g) at room temperature over 1 hr. After keeping at 0° C. overnight, precipitates were filtered and dried under reduced pressure to give N-Boc-L-tyrosine methyl ester 3 (126.9 g, yield 95.5%) as white crystals.

Provenance & Evidence