Chapter 17, Problem 41P

$\left(\text{R}\right)\text{-}(+)$ -Glyceraldehyde can be transformed into z $(+)$ -malic acid by the following synthetic route. Give stereochemical structures for the products of each step.

$\begin{array}{l}\left(\text{R}\right)-(+)-Glyceraldehyde\frac{B{r}_2,H_{2}O}{oxidation}(-)\text{-}glycericacid\underset{}{\overset{PB{r}_3}{\to }}\\ (-)\text{-}3\text{-}bromo\text{-}2hydroxypropanoicacid\underset{}{\overset{NaCN}{\to }}{C}_4{H}_{5}N{O}_3\underset{heat}{\overset{H_3{O}^{+}}{\to }}(+)\text{-}malicacid\end{array}$