1 2 upper phase to a solution of l alanine 1 78g 20 mmol in 10 na 2 co 3 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 u00b0 and 15 hr at 5 u00b0 poured into h 2 o 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 u00d7 500 ml the organic phase was washed with h 2 o dried mgso 4 filtered and evaporated ether petroleum ether was added to the residue which crystallized while being kept at 5 u00b0 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 u00b0 145 5 u00b0 u03b1 d 25 11 7 u00b0 c 1 ch 3 oh tlc r f 0 8 a 0 3 b uv max ch 2 cl 2 267 nm u03b518 950 290 5 280 301 6 200 analysis c 18 h 17 n 1 o 4 calcd c 69 44 h 5 50 n 4 50 found c 69 18 h 5 54 n 4 48 lit 16 mp 144 u00b0 145 u00b0 u03b1 d 25 3 48 u00b0 c 2 5 etoac fmoc l leucine 87 mp 152 u00b0 153 u00b0 d 25 7 4 lit 16 mp 155 u00b0 156 u00b0 u03b1 d 28 3 4 44 u00b0 fmoc l valine.