Chapter 13, Problem 13.30P

Interpretation Introduction

(a)

Interpretation:

It is to be shown how a retrosynthetic analysis might be constructed for the given synthesis.

Concept introduction:

Retrosynthesis is the planning of organic synthesis, working backwards from target molecule to a simpler precursor, regardless of any interaction with reagents. Thus, the basis of retrosynthetic analysis is the transform, which means the reverse of a synthetic reaction. The precursors are the compounds, which are either readily available or easy to produce. The transform is indicated by an open arrow $(\Rightarrow )$, called a retrosynthetic arrow. The arrow is drawn from the target molecule to the precursor, and no reagents or reaction conditions are mentioned. Retrosynthesis requires the disconnection of the target molecule by breaking of the bond to transform into the starting material. The bond disconnection in the target can be indicated by a wavy line.

Answer to Problem 13.30P

The retrosynthesis for the given synthesis is

Explanation of Solution

The given synthetic reaction is

In the given synthesis, the product differs from the starting compound by one ethyl group bonded to six-membered ring. Thus, the bond between the ethyl group and ring carbon in the target must break to transform it to the starting compound.

Therefore, retrosynthesis for the given synthetic reaction is

Conclusion

The retrosynthesis for the given synthetic reaction is shown by disconnecting the ethyl group from the ring.

Interpretation Introduction

(b)

Interpretation:

It is to be shown how a retrosynthetic analysis might be constructed for the given synthesis.

Concept introduction:

Retrosynthesis is the planning of organic synthesis, working backwards from target molecule to a simpler precursor, regardless of any interaction with reagents. Thus, the basis of retrosynthetic analysis is the transform, which means the reverse of a synthetic reaction. The precursors are the compounds, which are either readily available or easy to produce. The transform is indicated by an open arrow $(\Rightarrow )$, called a retrosynthetic arrow. The arrow is drawn from the target molecule to the precursor, and no reagents or reaction conditions are mentioned. Retrosynthesis requires the disconnection of the target molecule by breaking of the bond to transform into the starting material. The bond disconnection in the target can be indicated by a wavy line.

Answer to Problem 13.30P

The retrosynthesis for the given synthesis is

Explanation of Solution

The given synthetic reaction is

The given synthesis is of two steps; the final product is the target molecule. Thus, retrosynthesis could be planned from the target to the intermediate product to the starting material. The target molecule and the intermediate product differ in bromine and cyanide. Thus, the bond between the cyanide and ring carbon must break to transform into an intermediate. The intermediate and the starting molecule differ by bromine atom. Thus, the bond between the bromine and ring carbon must break to transform into the starting material.

Therefore, the retrosynthesis for the given synthetic reaction is

Conclusion

The retrosynthesis for the given synthetic reaction is shown by disconnecting the cyanide group and then by disconnecting the bromine atom from the ring.

Interpretation Introduction

(c)

Interpretation:

It is to be shown how a retrosynthetic analysis might be constructed for the given synthesis.

Concept introduction:

Retrosynthesis is the planning of organic synthesis, working backwards from target molecule to a simpler precursor, regardless of any interaction with reagents. Thus, the basis of retrosynthetic analysis is the transform, which means the reverse of a synthetic reaction. The precursors are the compounds, which are either readily available or easy to produce. The transform is indicated by an open arrow $(\Rightarrow )$, called a retrosynthetic arrow. The arrow is drawn from the target molecule to the precursor, and no reagents or reaction conditions are mentioned. Retrosynthesis requires the disconnection of the target molecule by breaking of the bond to transform into the starting material. The bond disconnection in the target can be indicated by a wavy line.

Answer to Problem 13.30P

The retrosynthesis for the given synthesis is

Explanation of Solution

The given synthetic reaction is

The given synthesis is of two steps; the final product is the target molecule. Thu, s the retrosynthesis could be planned from the target to the intermediate product to the starting material. The target molecule and the intermediate product differ in the benzyl group attached to the triple bonded carbon. Thus, the bond between the benzylic carbon and triple bonded carbon must break to transform into an intermediate. The intermediate can be transformed into the starting material by replacing the methyl group bonded to the oxygen atom by hydrogen.

Therefore, the retrosynthesis for the given synthetic reaction is

Conclusion

The retrosynthesis for the given synthetic reaction is shown by disconnecting the benzyl group from the triple bonded carbon and then by disconnecting the methyl group from the oxygen atom.

Interpretation Introduction

(d)

Interpretation:

It is to be shown how a retrosynthetic analysis might be constructed for the given synthesis.

Concept introduction:

Retrosynthesis is the planning of organic synthesis, working backwards from target molecule to a simpler precursor, regardless of any interaction with reagents. Thus, the basis of retrosynthetic analysis is the transform, which means the reverse of a synthetic reaction. The precursors are the compounds, which are either readily available or easy to produce. The transform is indicated by an open arrow $(\Rightarrow )$, called a retrosynthetic arrow. The arrow is drawn from the target molecule to the precursor, and no reagents or reaction conditions are mentioned. Retrosynthesis requires the disconnection of the target molecule by breaking of the bond to transform into the starting material. The bond disconnection in the target can be indicated by a wavy line.

Answer to Problem 13.30P

The retrosynthesis for the given synthesis is

Explanation of Solution

The given synthetic reaction is

The given synthesis is of two steps; the final product is the target molecule. Thus the retrosynthesis could be planned from the target to the intermediate product to the starting material. The target molecule has a double bond, which is removed in the intermediate product having the ydroxyl group at that position. Thus, the $\text{π}$ bond must break to transform the target into the intermediate. The intermediate can be transform into the starting material by breaking the bond between benzene and the five-membered ring.

Therefore, the retrosynthesis for the given synthetic reaction is

Conclusion

The retrosynthesis for the given synthetic reaction is shown by disconnecting the $\text{π}$ bond from the five-membered ring and then the bond between benzene and the five-membered ring.

Interpretation Introduction

(e)

Interpretation:

It is to be shown how a retrosynthetic analysis might be constructed for the given synthesis.

Concept introduction:

Retrosynthesis is the planning of organic synthesis, working backwards from target molecule to a simpler precursor, regardless of any interaction with reagents. Thus, the basis of retrosynthetic analysis is the transform, which means the reverse of a synthetic reaction. The precursors are the compounds, which are either readily available or easy to produce. The transform is indicated by an open arrow $(\Rightarrow )$, called a retrosynthetic arrow. The arrow is drawn from the target molecule to the precursor, and no reagents or reaction conditions are mentioned. Retrosynthesis requires the disconnection of the target molecule by breaking of the bond to transform into the starting material. The bond disconnection in the target can be indicated by a wavy line.

Answer to Problem 13.30P

The retrosynthesis for the given synthesis is

Explanation of Solution

The given synthetic reaction is

The given synthesis is of three steps; the final product is the target molecule. Thus, the retrosynthesis could be planned from the target to the second intermediate, then to the first intermediate, and finally into the starting material. The target molecule has the acetate group at the alpha position and the second intermediate has the bromine atom; thus, the bond between the alpha carbon and the oxygen of the acetate group must break. The second intermediate can be transformed into the first intermediate by breaking the bond between bromine and the alpha carbon. The first intermediate and the starting molecule differ by an additional methyl group; thus the bond between the alpha carbon and methyl must break to show the transform.

Therefore, the retrosynthesis for the given synthetic reaction is

Conclusion

The retrosynthesis for the given synthetic reaction is shown by disconnecting appropriate bonds.

Interpretation Introduction

(g)

Interpretation:

It is to be shown how a retrosynthetic analysis might be constructed for the given synthesis.

Concept introduction:

Retrosynthesis is the planning of organic synthesis, working backwards from target molecule to a simpler precursor, regardless of any interaction with reagents. Thus, the basis of retrosynthetic analysis is the transform, which means the reverse of a synthetic reaction. The precursors are the compounds, which are either readily available or easy to produce. The transform is indicated by an open arrow $(\Rightarrow )$, called a retrosynthetic arrow. The arrow is drawn from the target molecule to the precursor, and no reagents or reaction conditions are mentioned. Retrosynthesis requires the disconnection of the target molecule by breaking of the bond to transform into the starting material. The bond disconnection in the target can be indicated by a wavy line.

Answer to Problem 13.30P

The retrosynthesis for the given synthesis is

Explanation of Solution

The given synthetic reaction is

The given synthesis is of three steps; the final product is the target molecule. Thus; the retrosynthesis could be planned from the target to the second intermediate; then to the first intermediate; and finally into the starting material. The target can be transformed to the second intermediate by replacing the nitride group by bromine; thus the bond between the nitride group and carbon must break. The second intermediate can be transformed into the first intermediate by replacing the bromine by hydroxyl group; thus the bond between bromine and carbon must break. The first intermediate can be transformed into the starting material by replacing the hydroxyl group by ethoxy group.

Therefore, the retrosynthesis for the given synthetic reaction is

Conclusion

The retrosynthesis for the given synthetic reaction is shown by disconnecting appropriate bonds.