Chapter E, Problem E.48P

Interpretation Introduction

(a)

Interpretation:

The structure from the given IUPAC name with appropriate stereochemistry is to be drawn.

Concept introduction:

The root name in the given IUPAC name suggests the main chain or ring of carbon atoms in the compound. The suffix to root name indicates the highest priority functional group. The prefix with locant number indicates the number of substituents and their respective position at the main chain or a ring of carbon atoms.

The stereochemical designation and the locators are enclosed in parenthesis at the very beginning of the name. The stereochemistry at the chiral center is determined by assigning the priorities to the groups attached to the chiral center on the basis of atomic number of directly bonded atom. If the sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise the absolute configuration is $\text{R}$ and if it is counterclockwise the absolute configuration is $\text{S}$.

Answer to Problem E.48P

The structure for IUPAC name $\text{(2S, 3R, 4R)-2, 3-diamino-4-hydroxycyclopentanone}$ is:

Explanation of Solution

The given IUPAC name is $\text{(2S, 3R, 4R)-2, 3-diamino-4-hydroxycyclopentanone}$.

The root name in this IUPAC name ‘cyclopentan’ represents the main ring of five carbon atoms. The suffix ‘one’ represents the highest priority functional group - ketone. The prefixes $\text{2, 3-diamino}$ represent two ${\text{NH}}_{\text{2}}$ groups attached at $\text{C-2}$ and $\text{C-3}$ and $\text{4-hydroxy}$ represents $\text{OH}$ groups attached at $\text{C-4}$ in the main ring.

The structure has three chiral centers, $\text{C-2}$, $\text{C-3}$ and $\text{C-4}$. According to the IUPAC name, the absolute configuration at $\text{C-2}$ is $\text{S}$. The fourth priority group at $\text{C-2}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is counterclockwise.

Thus, for absolute configuration $\text{S}$, the fourth priority group must be away the observer that is below the plane. This suggests that the ${\text{NH}}_{\text{2}}$ group must be above the plane, and it can be represented by a wedge bond.

The absolute configuration at $\text{C-3}$ is $\text{R}$. The fourth priority group at $\text{C-3}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise.

Thus, for absolute configuration $\text{R}$, the fourth priority group must be away from the observer that is below the plane. This suggests that the ${\text{NH}}_{\text{2}}$ group must be above the plane and it can be represented by a wedge bond.

The absolute configuration at $\text{C-4}$ is $\text{R}$. The fourth priority group at $\text{C-4}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is counterclockwise.

Thus for absolute configuration $\text{R}$, the fourth priority group must be towards the observer i.e. above the plane which placed the $\text{OH}$ group below the plane and can be represented by dash bond.

Hence, the structure for is $\text{(2S, 3R, 4R)-2, 3-diamino-4-hydroxycyclopentanone}$:

Conclusion

The structure for the given IUPAC name is drawn by identifying the highest priority functional group from the suffix, main chain from root name, and the position for the substituents from the locant with appropriate stereochemistry.

Interpretation Introduction

(b)

Interpretation:

The structure from the given IUPAC name with appropriate stereochemistry is to be drawn.

Concept introduction:

The root name in the given IUPAC name suggests the main chain or ring of carbon atoms in the compound. The suffix to root name indicates the highest priority functional group. The prefix with locant number indicates the number of substituents and their respective position at the main chain or at a ring of carbon atoms.

The stereochemical designation and the locators are enclosed in parenthesis at the very beginning of the name. The stereochemistry at the chiral center is determined by assigning the priorities to the groups attached to chiral center on the basis of atomic number of directly bonded atom. If the sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise the absolute configuration is $\text{R}$ and if it is counterclockwise the absolute configuration is $\text{S}$.

Answer to Problem E.48P

The structure for IUPAC name $\text{(2R, 3R)-2-butyl-3-hydroxypentanedial}$ is:

Explanation of Solution

The given IUPAC name is $\text{(2R, 3R)-2-butyl-3-hydroxypentanedial}$.

The root name in this IUPAC name ‘pentane’ represents the main chain of five carbon atoms. The suffix ‘dial’ represents the highest priority functional group aldehyde located at both terminals of the main chain. The prefix $\text{2-butyl}$ represents the butyl group attached at $\text{C-2}$ and $\text{3-hydroxy}$ represents $\text{OH}$ group attached at $\text{C-3}$ to the main chain.

The structure has two chiral centers, $\text{C-2}$ and $\text{C-3}$. According to the IUPAC name, the absolute configuration at $\text{C-2}$ is $\text{R}$. The fourth priority group at $\text{C-2}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise.

Thus, for the absolute configuration $\text{R}$, the fourth priority group must be away from the observer i.e. below the plane This suggests that the $\text{CHO}$ group must be above the plane and it can be represented by a wedge bond.

The absolute configuration at $\text{C-3}$ is $\text{R}$. The fourth priority group at $\text{C-3}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise.

Thus for the absolute configuration $\text{R}$, the fourth priority group must be away from the observer i.e. below the plane. This suggests that the $\text{CHO}$ group must be above the plane and it can be represented by a wedge bond.

Hence, the structure for $\text{(2R, 3R)-2-butyl-3-hydroxypentanedial}$ is:

Conclusion

The structure for the given IUPAC name is drawn by identifying the highest priority functional group from the suffix, main chain from root name, and the position for the substituents from the locant with appropriate stereochemistry.

Interpretation Introduction

(c)

Interpretation:

The structure from the given IUPAC name with appropriate stereochemistry is to be drawn.

Concept introduction:

The root name in the given IUPAC name suggests the main chain or ring of carbon atoms in the compound. The suffix to root name indicates the highest priority functional group. The prefix with locant number indicates the number of substituents and their respective position at the main chain or at a ring of carbon atoms.

The stereochemical designation and the locators are enclosed in parenthesis at the very beginning of the name. The stereochemistry at the chiral center is determined by assigning the priorities to the groups attached to chiral center on the basis of atomic number of directly bonded atom. If the sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise the absolute configuration is $\text{R}$ and if it is counterclockwise the absolute configuration is $\text{S}$. The stereochemistry of $\text{C=C}$ bond is indicated by $\text{E/Z}$ notation. $\text{E}$ represents the trans double bond where the same priority groups are on opposite side of double bond. $\text{Z}$ represents the cis double bond where the same priority groups are on same side of double bond.

Answer to Problem E.48P

The structure for IUPAC name $\text{(4S, 5R)-4, 5-diaminoheptane-2, 3, 6-trione}$ is:

Explanation of Solution

The given IUPAC name is $\text{(4S, 5R)-4, 5-diaminoheptane-2, 3, 6-trione}$.

The root name in this IUPAC name ‘heptane’ represents the main chain of seven carbon atoms. The suffix ‘$\text{2, 3, 6-trione}$’ represents the highest priority functional group ketone located at $\text{C-2, C-3}$ and $\text{C-6}$ of the main chain. The prefix $\text{4, 5-diamino}$ represents two ${\text{NH}}_{\text{2}}$ groups are attached to the main ring at $\text{C-4}$ and $\text{C-5}$.

The structure has two chiral centers, $\text{C-4}$ and $\text{C-5}$. According to the IUPAC name, the absolute configuration at $\text{C-4}$ is $\text{S}$. The fourth priority group at $\text{C-4}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is counterclockwise.

Thus, for the absolute configuration $\text{S}$, the fourth priority group must be away from the observer i.e. below the plane. This suggests that the ${\text{NH}}_{\text{2}}$ group must be above the plane and it can be represented by a wedge bond.

The absolute configuration at $\text{C-5}$ is $\text{R}$. The fourth priority group at $\text{C-5}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is counterclockwise.

Thus, for the absolute configuration $\text{R}$, the fourth priority group must be towards the observer i.e. above the plane. This suggests that the ${\text{NH}}_{\text{2}}$ group must be below the plane, and it can be represented by a dash bond.

Hence, the structure for $\text{(4S, 5R)-4, 5-diaminoheptane-2, 3, 6-trione}$ is:

Conclusion

The structure for the given IUPAC name is drawn by identifying the highest priority functional group from the suffix, main chain from root name and the position for the substituents from the locant with appropriate stereochemistry.

Interpretation Introduction

(d)

Interpretation:

The structure from the given IUPAC name with appropriate stereochemistry is to be drawn.

Concept introduction:

The root name in the given IUPAC name suggests the main chain or ring of carbon atoms in the compound. The suffix to root name indicates the highest priority functional group. The prefix with locant number indicates the number of substituents and their respective position at the main chain or at a ring of carbon atoms.

The stereochemical designation and the locators are enclosed in parenthesis at the very beginning of the name. The stereochemistry at the chiral center is determined by assigning the priorities to the groups attached to chiral center on the basis of atomic number of directly bonded atom. If the sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise the absolute configuration is $\text{R}$ and if it is counterclockwise the absolute configuration is $\text{S}$. The stereochemistry of $\text{C=C}$ bond is indicated by $\text{E/Z}$ notation. $\text{E}$ represents the trans double bond where the same priority groups are on opposite side of double bond. $\text{Z}$ represents the cis double bond where the same priority groups are on same side of double bond.

Answer to Problem E.48P

The structure for IUPAC name $\text{(3E, 5R, 6Z)-5-hydroxy-7-methoxyocta-3, 6-dien-2-one}$ is:

Explanation of Solution

The given IUPAC name is $\text{(3E, 5R, 6Z)-5-hydroxy-7-methoxyocta-3, 6-dien-2-one}$.

The root name in this IUPAC name ‘octa’ represents the main chain of eight carbon atoms. The suffix ‘$\text{2-one}$’ represents the highest priority functional group is ketone located at $\text{C-2}$ on main chain. The prefix $\text{5-hydroxy}$ represents the presence of $\text{OH}$ group at $\text{C-5}$, $\text{7-methoxy}$ represents the presence of ${\text{OCH}}_{\text{3}}$ at $\text{C-7}$ and $\text{3, 6-dien}$ represents two $\text{C=C}$ bonds at $\text{C-3 and C-6}$ with stereochemistry $\text{E}$ and $\text{Z}$ respectively. Thus, the same priority groups must be on opposite side of double bond for $\text{3E}$, and the same priority groups must be on same side of double bond for $\text{6Z}$.

The structure has one chiral center, $\text{C-5}$. According to the IUPAC name, the absolute configuration at $\text{C-5}$ is $\text{R}$. The fourth priority group at $\text{C-5}$ is hydrogen. The sequence of priority order $\text{1}\to \text{2}\to \text{3}$ is clockwise.

Thus for the absolute configuration $\text{R}$, the fourth priority group must be away from the observer i.e. below the plane. This suggests that the $\text{OH}$ group must be above the plane and it can be represented by a wedge bond.

Hence, the structure for $\text{(3E, 5R, 6Z)-5-hydroxy-7-methoxyocta-3, 6-dien-2-one}$ is:

Conclusion

The structure for the given IUPAC name is drawn by identifying the highest priority functional group from the suffix, main chain from root name and the position for the substituents from the locant with appropriate stereochemistry.