Chapter E, Problem E.46P

Interpretation Introduction

(a)

Interpretation:

The IUPAC name for the given compound with appropriate stereochemical designation is to be assigned.

Concept introduction:

In naming organic compounds, the functional groups other than highest priority functional groups are treated as substituents. The root name is established by identifying the longest carbon chain or a ring containing functional group. Remove the “e” from the normal ‘ane’, ‘ene’, or ‘yne’ ending and add the suffix that corresponds to the highest-priority functional group. Prefixes are used to denote number of identical substituents. Number the carbon chain in a way that the functional group and the substituents attached get the lowest number. The position of functional group and substituents on parent chain or ring is indicated by the respective locant number just before the suffix. The substituents are written in alphabetical order when writing the IUPAC name.

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 atoms. If the sequence of priority order $\text{R}$ is clockwise, the absolute configuration is R, and if it is counterclockwise, the absolute configuration is $\text{S}$.

Answer to Problem E.46P

The name of the given compound is $\text{(3R, 4R, 5R)-5-Amino-3-hydroxy-4-nitrohexan-2-one}$

Explanation of Solution

The given compound is:

In this compound, the highest priority functional group is ketone, thus, the suffix ‘one’ is added to the root name. The main chain is of six carbon atoms that indicates the root name as “hexan”. The substituents are $\text{OH}$, ${\text{NO}}_{\text{2}}$, and ${\text{NH}}_{\text{2}}$ attached to the main chain. The carbon atoms in the chain are numbered in a way that the highest priority functional group is encountered earliest.

The ketonic carbon is numbered as $\text{C-2}$. The position of $\text{OH}$ group is $\text{C-3}$, ${\text{NO}}_{\text{2}}$ group is $\text{C-4}$, and ${\text{NH}}_{\text{2}}$ group is $\text{C-5}$. The compound has three chiral centers $\text{C-3, C-4}$, and $\text{C-5}$.

The fourth group, attached to chiral center $\text{C-3}$, is hydrogen atom, and it is below the plane i.e. away from the observer. The priority assigned to the other three groups is:

In the order of decreasing sequence rule $\text{1}\to \text{2}\to \text{3}$, the precedence is clockwise where the fourth priority group is below the plane. Thus, the absolute configuration is $\text{R}$.

The fourth group attached to the chiral center $\text{C-4}$ is a hydrogen atom, and it is above the plane i.e. towards the observer. The priority assigned to other three groups is:

In the order of decreasing sequence rule, $\text{1}\to \text{2}\to \text{3}$, the precedence is counterclockwise where the fourth priority group is above the plane. Thus, the absolute configuration is $\text{R}$.

The fourth group, attached to chiral center $\text{C-5}$, is hydrogen atom, and it is below the plane i.e. away from the observer. The priority assigned to other three groups is:

In the order of decreasing sequence rule $\text{1}\to \text{2}\to \text{3}$, precedence is clockwise where the fourth priority group is below the plane. Thus, the absolute configuration is $\text{R}$.

Hence the given compound is named as:

$\text{(3R, 4R, 5R)-5-Amino-3-hydroxy-4-nitrohexan-2-one}$.

Conclusion

The given compound is named by identifying the main chain containing the functional group and the substituents attached with appropriate stereochemistry.

Interpretation Introduction

(b)

Interpretation:

The IUPAC name for the given compound with appropriate stereochemical designation is to be assigned.

Concept introduction:

In naming organic compounds, the functional groups other than highest priority functional groups are treated as substituents. The root name is established by identifying the longest carbon chain or a ring containing functional group. Remove the “e” from the normal ‘ane’, ‘ene’, or ‘yne’ ending and add the suffix that corresponds to the highest-priority functional group. Prefixes are used to denote number of identical substituents. Number the carbon chain in a way that the functional group and the substituents attached get the lowest number. The position of functional group and substituents on parent chain or ring is indicated by the respective locant number just before the suffix. The substituents are written in alphabetical order when writing the IUPAC name.

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 $\text{R}$ is clockwise the absolute configuration is R and if it is counterclockwise the absolute configuration is $\text{S}$.

Answer to Problem E.46P

The name of the given compound is:

$\text{(1S, 3R, 6R)-3-Hydroxy-6-methyl-2-oxocyclohex-4-enecarbaldehyde}$.

Explanation of Solution

The given compound is:

In this compound, the main ring is of six carbon atoms containing $\text{C=C}$ bond indicates the root name ‘cyclohex’. The highest priority functional group is aldehyde $\text{CHO}$. The carbonyl carbon of aldehyde is not a part of the ring, thus, the suffix ‘carbaldehyde’ is added to the root name. The substituents are $\text{OH}$ and ${\text{CH}}_3$ attached to main ring. The ketonic carbonyl group of the ring is also considered as a substituent and used as a suffix ‘oxo’. The carbon atoms in the ring are numbered in a way that the highest priority functional group is encountered earliest.

The ketonic carbon is numbered $\text{C-2}$. The position of $\text{OH}$ group is $\text{C-3}$; ${\text{CH}}_3$ group is $\text{C-6}$, and $\text{C=C}$ bond is $\text{C-4}$. The compound has three chiral centers $\text{C-1}$, $\text{C-3}$, and $\text{C-6}$.

The fourth group attached to the chiral center $\text{C-1}$ is hydrogen atom, and it is below the plane i.e. away from the observer. The priority assigned to other three groups is:

In the order of decreasing sequence rule $\text{1}\to \text{2}\to \text{3}$, precedence is counterclockwise where the fourth priority group is below the plane. Thus, the absolute configuration is $\text{S}$.

The fourth group attached to chiral center $\text{C-3}$ is hydrogen atom, and it is above the plane i.e. towards the observer. The priority assigned to other three groups is:

In the order of decreasing sequence rule $\text{1}\to \text{2}\to \text{3}$, the precedence is counterclockwise where the fourth priority group is above the plane. Thus, the absolute configuration is $\text{R}$.

The fourth group attached to chiral center $\text{C-6}$ is hydrogen atom, and it is below the plane i.e. away from the observer. The priority assigned to other three groups is:

In the order of decreasing sequence rule $\text{1}\to \text{2}\to \text{3}$, the precedence is clockwise where the fourth priority group is below the plane. Thus, the absolute configuration is $\text{R}$.

Hence, the given compound is named as:

$\text{(1S, 3R, 6R)-3-Hydroxy-6-methyl-2-oxocyclohex-4-enecarbaldehyde}$.

Conclusion

The given compound is named by identifying the main chain containing functional group and the substituents attached with appropriate stereochemistry.

Interpretation Introduction

(c)

Interpretation:

The IUPAC name for the given compound with appropriate stereochemical designation is to be assigned.

Concept introduction:

In naming organic compounds, the functional groups other than highest priority functional groups are treated as substituents. The root name is established by identifying the longest carbon chain or a ring containing functional group. Remove the “e” from the normal ‘ane’, ‘ene’, or ‘yne’ ending and add the suffix that corresponds to the highest-priority functional group. Prefixes are used to denote number of identical substituents. Number the carbon chain in a way that the functional group and the substituents attached gets lowest number. The position of functional group and substituents on parent chain or ring is indicated by the respective locant number just before the suffix. The substituents are written in alphabetical order when writing the IUPAC name.

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 $\text{R}$ is clockwise the absolute configuration is R and if it is counterclockwise the absolute configuration is $\text{S}$.

Answer to Problem E.46P

The name of given compound is:

$\text{(5R, 6R)-5-Amino-7-hydroxy-6-methylheptane-2, 3, 4-trione}$.

Explanation of Solution

The given compound is:

In this compound, the main chain is of seven carbon atoms which indicates the root name as ‘heptane’. The highest priority functional group is ketone. The chain has three carbonyl groups, therefore, the suffix ‘trione’ is added to the root name. The substituents are ${\text{OH, NH}}_{\text{2}}$, ${\text{CH}}_3$ attached to the main chain. The carbon atoms in the ring are numbered in a way that the highest priority functional group is encountered earliest.

The ketonic carbons are numbered as $\text{C-2}$, $\text{C-3}$ and $\text{C-4}$. The position of ${\text{NH}}_{\text{2}}$ group is $\text{C-5}$, ${\text{CH}}_3$ group is $\text{C-6}$, and $\text{OH}$ is $\text{C-7}$. The compound has two chiral centers $\text{C-5}$ and $\text{C-6}$.

The fourth group attached to chiral center $\text{C-5}$ is hydrogen atom, and it is below the plane i.e. away from the observer. The priority assigned to other three groups is:

In the order of decreasing sequence rule $\text{1}\to \text{2}\to \text{3}$, precedence is clockwise where the fourth priority group is below the plane. Thus the absolute configuration is $\text{R}$.

The fourth group attached to chiral center $\text{C-6}$ is hydrogen atom, and it is below the plane i.e. away from the observer. The priority assigned to other three groups is:

In the order of decreasing sequence rule $\text{1}\to \text{2}\to \text{3}$, precedence is clockwise where the fourth priority group is below the plane. Thus, the absolute configuration is $\text{R}$.

Hence, the given compound is named as:

$\text{(5R, 6R)-5-Amino-7-hydroxy-6-methylheptane-2, 3, 4-trione}$.

Conclusion

The given compound is named by identifying the main chain containing functional group and the substituents attached with appropriate stereochemistry.