Sodium Hydroxide → 1-(Phenylmethyl) (2S,4R)-4-fluoro-1,2-pyrrolidinedicarboxylate

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Reaction Steps

Following the procedure of Example 19(d), the methyl ester product from part (d) is saponified with 11.5 ml. of 2 N sodium hydroxide in 50 ml. methanol to give 5.3 g. of the desired product as a pale yellow viscous oil. This material is converted to the cyclohexylamine salt by treatment with 2 g. of cyclohexylamine in 25 ml. of ethanol. 4.7 g. of cyclohexylamine salt are obtained; m.p. 188°-191° (s. 183°); [α]D25 -42° (c=1%, methanol). Crystallization from 55 ml. of isopropanol gives 3.7 g. of colorless cyclohexylamine salt; m.p. 194°-196° (s. 187°); [α]D25 -44° (c=1%, methanol).

Provenance & Evidence