Water → N-((9H-Fluoren-9-ylmethoxy)carbonyl)-L-alanine

Participants

Reaction Steps

To a solution of L-alanine (1.78g, 20 mmol) in 10% Na2CO3 (53 ml) was added dropwise (within 50 min) with stirring and ice bath cooling a solution of 9-fluorenylmethyl chloroformate (5.17g, 20 mmol) in dioxane (40 ml). The mixture was stirred for 1 hr at 0° and 15 hr at 5°, poured into H2O (1.5 liters) and extracted with ether (2 x). The aqueous layer was cooled in an ice bath, acidified with concentrated HCl to pH 2-3 (white precipitate) and extracted with EtOAc (3 × 500 ml). The organic phase was washed with H2O, dried (MgSO4), filtered, and evaporated. Ether-petroleum ether was added to the residue which crystallized while being kept at 5°. The crude product (5.94g, 95.5%) was recrystallized from methanol-petroleum ether to yield colorless crystals of Fmoc-L-alanine (5.61g, 90.2%), mp 144.5°-145.5° ; [α]D25 = - 11.7° (c 1, CH3OH); tlc, Rf 0.8 (A), 0.3 (B); uv max (CH2Cl2) 267 nm (ε18,950), 290 (5,280), 301 (6,200).

Provenance & Evidence