(a) On the basis of the following sequence of reactions, Emil Fischer was able to show that L-(-)-serine and L-(+)-alanine have the same configuration. Write Fischer projections for the intermediates A-C:

(b) The configuration of L-(+)-cysteine can be related to that of L-(-)-serine through the following reactions. Write Fischer projections for D and E:

(c) The configuration of L-(-)-asparagine can be related to that of L-(-)-serine in the following way. What is the structure of F?

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Na Hg (1) H3O, H20, heat (2) HO PCs )-Serine CH,O AC0CINO3) B(CH,CNO 2OC(CHeCINO dilute HOr L+)-alanine но. NaSH (1) H2O, H20, heat (2) HO B (from part a) D (C4HBCINO2) L (+)-cysteine --→ L-(-)-Asparagine し-(-)-Asparagine r'a。BrHO F Hofmann rearrangement C (from part a) . NH