Question

assign the indicated chiral carbons as r or s.
a.
i: r
ii: r
b.
i: r
ii: s
c.
i: s
ii: r
d.
i: s
ii: s

Explanation:

Step1: Determine priority of groups

For chiral - carbon I: The groups attached are -OH (highest priority as O has highest atomic number among the attached atoms), -NHCOCHCl₂, -CH₂OH, and -H (lowest priority). When we arrange the groups in order of decreasing priority and view the molecule with the lowest - priority group (-H) away from us, the direction of the remaining groups is clock - wise. So, chiral - carbon I has an R configuration.

Step2: Determine priority of groups for chiral - carbon II

The groups attached are the benzene ring (higher priority due to the multiple - bonded nature and higher atomic number of carbon atoms in the ring), -NHCOCHCl₂, -CH₂OH, and -H (lowest priority). When we arrange the groups in order of decreasing priority and view the molecule with the lowest - priority group (-H) away from us, the direction of the remaining groups is counter - clockwise. So, chiral - carbon II has an S configuration.

Answer:

B. R, S