Chapter 28, Problem 28.40P

Convert each compound to a Fischer projection and label each stereogenic center as $R$ or $S$

a. c. e.

b. d. f.

Interpretation Introduction

(a)

Interpretation: The given compound is to be converted into Fischer projection and the stereogenic center of a compound is to be labeled as $R$ or $S$.

Concept introduction: In Fischer projection formula, the horizontal and vertical line represents the bonds that are present above and below the plane, respectively. The verticals bonds are represented as dashed wedge and horizontal bonds as dark wedge.

Answer to Problem 28.40P

The Fischer projection of given compound is,

The stereogenic center of a compound is labeled as $S$.

Explanation of Solution

The structure of given compound is,

Figure 1

The horizontal and vertical line represents the bonds in front of the plane and behind the plane. Hence, the Fischer projection of given compound is shown below.

Figure 2

In the compound, ${\text{COOH, Br, CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to carbon atom. The atomic number of $\text{C, Br}$ and $\text{H}$ is $\text{6, 35}$ and $1$ respectively. Thus, first priority is given to $\text{Br}$ substituent. There are two substituents i.e. ${\text{COOH, CH}}_{\text{3}}$ are connected to the stereogenic centre through the carbon atom. Now, the priority is given on the basis of atomic number of second atom which is attached to the carbon atom. The carbon of $\text{COOH}$ is connected the oxygen atom and the atomic number of oxygen is $8$ while the another carbon atom of ${\text{CH}}_{\text{3}}$ is connected the carbon atom and the atomic number of carbon is $6$. Thus, the second priority is given to $\text{COOH}$ substituent then third priority to ${\text{CH}}_{\text{3}}$ substituent. Complete the circle in decreasing order of priority from $1\to 2\to 3$ is shown below.

Figure 3

The circle rotates in the anticlockwise direction. Thus, the given compound is labeled as $S$.

Hence, the Fischer projection of given compound is shown in Figure 2 and the stereogenic center of a compound is labeled as $S$.

Conclusion

The Fischer projection of given compound is shown in Figure 2 and the stereogenic center of a compound is labeled as $S$.

Interpretation Introduction

(b)

Interpretation: The given compound is to be converted into Fischer projection and the stereogenic center is to be labeled as $R$ or $S$.

Concept introduction: In Fischer projection formula, the horizontal and vertical line represents the bonds that are present above and below the plane, respectively. The verticals bonds are represented as dashed wedge and horizontal bonds as dark wedge.

Answer to Problem 28.40P

The Fischer projection of given compound is,

The stereogenic center of a compound is labeled as $S$.

Explanation of Solution

The structure of given compound is,

Figure 4

The given compound is redrawn. The horizontal and vertical line represents the bonds in front of the plane and behind the plane is shown below.

Figure 5

Hence, the Fischer projection of given compound is shown below.

Figure 6

In the compound, ${\text{CH}}_3{\text{CH}}_2{\text{O, CH}}_{\text{3}},{\text{CH}}_2{\text{CH}}_3$ and ${\text{OCH}}_3$ substituents are attached to carbon atom. The atomic number of $\text{C}$ and $\text{O}$ is $6$ and $8$ respectively. Thus, first priority is given to $\text{O}$ containing substituent. There are two substituents i.e. ${\text{CH}}_3{\text{CH}}_2{\text{O, OCH}}_{\text{3}}$ are connected to the stereogenic centre through the oxygen atom and third atom in these substituent is also same(carbon) Now, the priority is given on the basis of atomic number of third atom. The third atom of ${\text{CH}}_3{\text{CH}}_2\text{O}$ is carbon atom and the atomic number of carbon is $6$ while the third atom of ${\text{OCH}}_{\text{3}}$ is connected to the hydrogen atom and the atomic number of hydrogen is $1$. Thus, the first and second priorities are given to ${\text{CH}}_3{\text{CH}}_2\text{O}$ and ${\text{OCH}}_{\text{3}}$ substituent.

Similarly, the third and forth priorities are given to ${\text{CH}}_2{\text{CH}}_3$ and ${\text{CH}}_{\text{3}}$ substituents. Complete the circle in decreasing order of priority from $1\to 2\to 3$ is shown below.

Figure 7

The circle rotates in the anticlockwise direction. Thus, the given compound is labeled as $S$.

Hence, the Fischer projection of given compound is shown in Figure 6 and the stereogenic center of a compound is labeled as $S$.

Conclusion

The Fischer projection of given compound is shown in Figure 6 and the stereogenic center of a compound is labeled as $S$.

Interpretation Introduction

(c)

Interpretation: The given compound is to be converted into Fischer projection and the stereogenic center is to be labeled as $R$ or $S$.

Concept introduction: In Fischer projection formula, the horizontal and vertical line represents the bonds that are present above and below the plane, respectively. The verticals bonds are represented as dashed wedge and horizontal bonds as dark wedge.

Answer to Problem 28.40P

The Fischer projection of given compound is,

The stereogenic center of a compound is labeled as $S$.

Explanation of Solution

The structure of given compound is,

Figure 8

The given compound is redrawn. The horizontal and vertical line represents the bonds in front of the plane and behind the plane. Hence, the Fischer projection of given compound is shown below.

Figure 9

Hence, the Fischer projection of given compound is shown below.

Figure 10

In the compound, ${\text{Cl, Br, CH}}_2{\text{CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to carbon atom. The atomic number of $\text{C, Br}$ and $\text{Cl}$ is $\text{6, 35}$ and $17$ respectively. Thus, first priority is given to $\text{Cl}$ substituent. Thus, the second priority is given to $\text{Br}$ substituent then third priority to ${\text{CH}}_2{\text{CH}}_{\text{3}}$ substituent. Complete the circle in decreasing order of priority from $1\to 2\to 3$ is shown below.

Figure 11

The circle rotates in the anticlockwise direction. Thus, the given compound is labeled as $S$.

Hence, the Fischer projection of given compound is shown in Figure 10 and the stereogenic center of a compound is labeled as $S$.

Conclusion

The Fischer projection of given compound is shown in Figure 10 and the stereogenic center of a compound is labeled as $S$.

Interpretation Introduction

(d)

Interpretation: The given compound is to be converted into Fischer projection and the stereogenic center is to be labeled as $R$ or $S$.

Concept introduction: In Fischer projection formula, the horizontal and vertical line represents the bonds that are present above and below the plane, respectively. The verticals bonds are represented as dashed wedge and horizontal bonds as dark wedge.

Answer to Problem 28.40P

The Fischer projection of given compound is,

The stereogenic center of a compound are labeled as $2S$ and $3S$.

Explanation of Solution

The structure of given compound is,

Figure 12

The horizontal and vertical line represents the bonds in front of the plane and behind the plane. Hence, the Fischer projection of given compound is shown below.

Figure 13

In the compound, $\text{-CH}\left(\text{Cl}\right)\left({\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}\right){\text{, Br, CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to ${\text{C}}_2$ atom. The atomic number of $\text{C, Br}$ and $\text{H}$ is $\text{6, 35}$ and $1$ respectively. Thus, first priority is given to $\text{Br}$ substituent. Thus, the second and third priorities are given to $\text{-CH}\left(\text{Cl}\right)\left({\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}\right){\text{, CH}}_{\text{3}}$ substituents. Complete the circle in decreasing order of priority from $1\to 2\to 3$. The circle rotates in the clockwise direction, configuration at ${\text{C}}_2$ would be $R$ but forth priority should be come away from viewer. Therefore the configuration gets reversed. Thus, configuration at ${\text{C}}_2$ is labeled as $S$.

Similarly, in the ${\text{C}}_3$ atom, the first and second priorities are given to $\text{Cl}$ and $\text{-CH}\left(\text{Br}\right)\left({\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}\right)$. Complete the circle in decreasing order of priority from $1\to 2\to 3$ The circle rotates in the clockwise direction, configuration at ${\text{C}}_3$ would be $R$ but forth priority should be come away from viewer. Therefore the configuration gets reversed. Thus, configuration at ${\text{C}}_3$ is labeled as $S$. The priorities at ${\text{C}}_2$ and ${\text{C}}_3$ are shown below.

Figure 14

Hence, the Fischer projection of given compound is shown in Figure 13 and the stereogenic center of a compound are labeled as $2S$ and $3S$.

Conclusion

The Fischer projection of given compound is shown in Figure 13 and the stereogenic center of a compound are labeled as $2S$ and $3S$.

Interpretation Introduction

(e)

Interpretation: The given compound is to be converted into Fischer projection and the stereogenic center is to be labeled as $R$ or $S$.

Concept introduction: In Fischer projection formula, the horizontal and vertical line represents the bonds that are present above and below the plane, respectively. The verticals bonds are represented as dashed wedge and horizontal bonds as dark wedge.

Answer to Problem 28.40P

The Fischer projection of given compound is,

The stereogenic center of a compound as $2S$ and $3S$.

Explanation of Solution

The structure of given compound is,

Figure 15

The given compound is redrawn. The horizontal and vertical line represents the bonds in front of the plane and behind the plane as shown below.

Figure 16

Hence, the Fischer projection of given compound is shown below.

Figure 17

In the compound, $\text{-CH}\left(\text{Br}\right)\left({\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}\right){\text{, Br, CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to ${\text{C}}_2$ atom. The atomic number of $\text{C, Br}$ and $\text{H}$ is $\text{6, 35}$ and $1$ respectively. Thus, first priority is given to $\text{Br}$ substituent. Thus, the second and third priorities are given to $\text{-CH}\left(\text{Br}\right)\left({\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}\right){\text{, CH}}_{\text{3}}$ substituents. Complete the circle in decreasing order of priority from $1\to 2\to 3$. The circle rotates in the clockwise direction, configuration at ${\text{C}}_2$ would be $R$ but forth priority should be come away from viewer. Therefore the configuration gets reversed. Thus, configuration at ${\text{C}}_2$ is labeled as $S$.

Similarly, in the ${\text{C}}_3$ atom, the first and second priorities are given to $\text{Br}$ and $\text{-CH}\left(\text{Br}\right)\left({\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}\right)$. Complete the circle in decreasing order of priority from $1\to 2\to 3$ The circle rotates in the clockwise direction, configuration at ${\text{C}}_3$ would be $R$ but forth priority should be come away from viewer. Therefore the configuration gets reversed. Thus, configuration at ${\text{C}}_3$ is labeled as $S$. The priorities at ${\text{C}}_2$ and ${\text{C}}_3$ are shown below.

Figure 18

Hence, the Fischer projection of given compound is shown in Figure 17 and the stereogenic center of a compound are labeled as $2S$ and $3S$.

Conclusion

The Fischer projection of given compound is shown in Figure 17 and the stereogenic center of a compound are labeled as $2S$ and $3S$.

Interpretation Introduction

(f)

Interpretation: The given compound is to be converted into Fischer projection and the stereogenic center is to be labeled as $R$ or $S$.

Concept introduction: In Fischer projection formula, the horizontal and vertical line represents the bonds that are present above and below the plane, respectively. The verticals bonds are represented as dashed wedge and horizontal bonds as dark wedge.

Answer to Problem 28.40P

The Fischer projection of given compound is,

The stereogenic center of a compound are labeled as $2S$, $3S$ and $3R$.

Explanation of Solution

The structure of given compound is,

Figure 19

The Fischer projection is drawn by converting the stable staggered conformation into less stable eclipsed conformation. The bonds present below the plane in eclipsed conformation are placed on the left side of the horizontal line in Fischer projection formula as shown below.

Figure 20

Hence, the Fischer projection of given compound is shown below.

Figure21

In the compound, $\text{-CH}\left(\text{OH}\right)\text{CHOH}\left({\text{CH}}_{\text{2}}\text{OH}\right)\text{, OH, CHO}$ and $\text{H}$ substituents are attached to ${\text{C}}_2$ atom. Thus, the first and second priorities are given to $\text{ OH, CHO}$ substituents then third priority is given to $\text{-CH}\left(\text{OH}\right)\text{CHOH}\left({\text{CH}}_{\text{2}}\text{OH}\right)$. Complete the circle in decreasing order of priority from $1\to 2\to 3$. The circle rotates in the clockwise direction, configuration at ${\text{C}}_2$ would be $R$ but forth priority should be come away from viewer. Thus, configuration at ${\text{C}}_2$ is labeled as $S$.

Similarly, in the ${\text{C}}_3$ atom, the first and second priorities are given to $\text{OH}$ and $\text{-CHOH}\left(\text{CHO}\right)$. Complete the circle in decreasing order of priority from $1\to 2\to 3$ The circle rotates in the clockwise direction, configuration at ${\text{C}}_3$ would be $R$ but forth priority should be come away from viewer. Therefore the configuration gets reversed. Thus, configuration at ${\text{C}}_3$ is labeled as $S$.

Similarly, in the ${\text{C}}_4$ atom, the first and second priorities are given to $\text{OH}$ and $\text{-CHO}{\left(\text{CHOH}\right)}_2$. Complete the circle in decreasing order of priority from $1\to 2\to 3$. The circle rotates in the anticlockwise direction, configuration at ${\text{C}}_4$ would be $S$ but forth priority should be come away from viewer. Therefore the configuration gets reversed. Thus, configuration at ${\text{C}}_4$ is labeled as $R$. The priorities at ${\text{C}}_2$, ${\text{C}}_3$ and ${\text{C}}_4$ are shown below.

Figure 22

Hence, the Fischer projection of given compound is shown in Figure 21 and the stereogenic center of a compound are labeled as $2S$, $3S$ and $3R$.

Conclusion

The Fischer projection of given compound is shown in Figure 21 and the stereogenic center of a compound are labeled as $2S$, $3S$ and $3R$.