Chapter 24, Problem 19P

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

$\begin{array}{l}(-)\text{-}Serine\underset{C{H}_{3}OH}{\overset{HCl}{\to }}A\left(C_4{H}_{10}ClN{O}_3\right)\underset{}{\overset{PC{l}_5}{\to }}B\left(C_4{H}_{9}C{l}_{2}N{O}_2\right)\underset{\left(2\right)H{O}^{-}}{\overset{\left(1\right)H_3{O}^{+},H_{2}O,heat}{\to }}\\ C\left(C_3{H}_{6}ClN{O}_2\right)\underset{dilute{H}_3{O}^{-}}{\overset{Na-Hg}{\to }}L\text{-}(+)\text{-}alanine\end{array}$

(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:

$\begin{array}{l}B\left(fromparta\right)\underset{}{\overset{H{O}^{-}}{\to }}D\left(C_4{H}_{8}ClN{O}_2\right)\underset{}{\overset{NaSH}{\to }}E\left(C_4{H}_{9}N{O}_{2}S\right)\underset{\left(2\right)H{O}^{-}}{\overset{\left(1\right)H_3{O}^{+},H_{2}O,heat}{\to }}\\ L\text{-}(+)\text{-}cysteine\end{array}$

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