Chapter 12, Problem 12.43P

Interpretation Introduction

(a)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

Reduction of an alkene by the addition of H₂ to one or both of the pi bonds. When an alkene is treated with two or more equivalents of H₂ and using the Pd catalyst, reduction of both the pi bonds occurs. Syn addition of H₂ to forms a cis alkene product and then form an alkane. Four new C-H bonds are formed.

Answer to Problem 12.43P

The reagents needed to carry out the transformation is H₂/Pd-C to form the product

Explanation of Solution

Reduction of an alkene by the addition of H₂ to one or both of the pi bonds. When an alkene is treated with two or more equivalents of H₂ and using the Pd catalyst, reduction of both the pi bonds occurs. Syn addition of one equivalent of H₂ to forms a cis alkane product. Thus one more addition of a equivalent of H₂ to form an alkane. Four new C-H bonds are formed.

Conclusion

Reduction of the given transformation is carried out by using the Hydrogen (1 equ)/Pd-C reagent

Interpretation Introduction

(b)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

The given product is obtained by epoxidation, it is a stereospecific reaction because cis and trans alkenes yield different stereoisomers as products. A cis alkene gives an epoxide with cis substituents. A trans alkene gives an epoxide with trans substituents

Answer to Problem 12.43P

The reagents needed to carry out the transformation is mCPBA or metachloro perbenzoic acid to form the product

Explanation of Solution

Two C-O bonds are formed to one oxygen atom with one electron pair from the peroxyacid and one from the pi bond. Then the weak oxygen-oxygen bond is broken to form the epoxide product.

Conclusion

Reduction of the given transformation is carried out by using the mCPBA or metachloro perbenzoic acid reagent.

Interpretation Introduction

(c)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

The given product is dihydroxylation product. It is the addition of two hydroxy groups to a double bond, forming a 1, 2-diol or glycol. Depending on the reagent, the formed two new OH groups can be added to the opposite sides (anti addition) or the same side (syn addition) of the double bond. In the given transformation is cis product formed by the syn addtion

Answer to Problem 12.43P

The reagents needed to carry out the transformation is OsO₄, NaHSO₃+H₂O or KMnO₄+H₂O to form the product

Explanation of Solution

The reagent adds two oxygen atoms to the same side of the double bond in a syn fashion-to yield a cyclic intermediate. The cyclic intermediate is then to hydrolysis to cleaves the metalo oxygen bonds, forming the cis-1, 2-diol. With OsO4, sodium bisulfite (NaHSO3) is added for the hydrolysis to occur. In KMnO₄ only H2O is used.

Conclusion

Reduction of the given transformation is carried out by using the OsO₄, NaHSO₃+H₂O or KMnO₄+H₂O reagent.

Interpretation Introduction

(d)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

The given product is reduction product. Reduction of these C-X sigma bonds is an example of nucleophilic substitution, in which LiAlH₄ serves as a source of a hydride nucleophile (H^-). Because H^- is a strong nucleophile, the reaction follows an SN² mechanism.

Answer to Problem 12.43P

The reagents needed to carry out the transformation is LiALH₄+H₂O to form the product

Explanation of Solution

Because the reduction reaction follows an SN² mechanism. The unhindered CH₃X and 1 ° alkyl halides are more easily reduced than more substituted 2° and 3° halides. In unsymmetrical epoxides, nucleophilic attack of H^- (from LiAIH₄) occurs at the less substituted carbon atom.

Conclusion

Reduction of the given transformation is carried out by using the LiALH₄+H₂O reagent.

Interpretation Introduction

(e)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

The given product is antihydroxylation product. Opening of the epoxy ring by OH anion and water to form the anti dihydroxylated product.

Answer to Problem 12.43P

The reagents needed to carry out the transformation is ^-OH+H₂O to form the product

Explanation of Solution

Epoxidation of cyclo-pentene adds an O atom from either above or below the plane of the double bond to form a single achiral epoxide. Opening of the epoxide ring occurs by the backside attack at either C - O bond. Because the epoxide is above the plane of the five-membered ring, nucleophilic attack occurs from below plane.

Conclusion

Reduction of the given transformation is carried out by using the ^-OH+H₂O reagent.

Interpretation Introduction

(f)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

The given product is antihydroxylation product. Opening of the epoxy ring by OH anion and water to form the anti dihydroxylated product.

Answer to Problem 12.43P

The reagents needed to carry out the transformation is PBr₃ or HBr to form the product

Explanation of Solution

The bromo product is formed similar to SN² fashion. Where bromo anion attack at the carbon where the alcohol attached so that bromo anion attack by the backside attack to for the bromo product.

Conclusion

Reduction of the given transformation is carried out by using the PBr₃ or HBr reagent.

Interpretation Introduction

(g)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

CrO₃/H₂SO₄+H₂O is an oxidizing agent. Oxidizing agents. CrO₃ are strong, nonselective oxidants used in aqueous acid H₂SO₄+H₂O. The general mechanism is given below.

Answer to Problem 12.43P

The reagents needed to carry out the transformation is CrO₃/H₂SO₄+H₂O to form the product

Explanation of Solution

The oxidation of alcohols to carbonyl compounds is typically carried out by PCC or CrO₃(where Cr⁶⁺ oxidants, which are reduced to Cr³⁺) to form the products. Oxidation of a 2 ° alcohol to an aldehyde or ketone occurs by the three-step mechanism similar to PCC reagent for the 2 ° alcohol.

Conclusion

Reduction of the given transformation is carried out by using the CrO₃/H₂SO₄+H₂O reagent.

Interpretation Introduction

(h)

Interpretation:

To identify the reagents needed to carry out the transformation

Concept introduction:

The given product is reduction product. Reduction of these C-X sigma bonds is an example of nucleophilic substitution, in which LiAlH₄ serves as a source of a hydride nucleophile (H^-). Because H^- is a strong nucleophile, the reaction follows an SN² mechanism

Answer to Problem 12.43P

The reagents needed to carry out the transformation is LiALH₄+H₂O to form the product

Explanation of Solution

Because the reduction reaction follows an SN² mechanism. The unhindered CH₃X and 1 ° alkyl halides are more easily reduced than more substituted 2° and 3° halides. In unsymmetrical epoxides, nucleophilic attack of H^- (from LiAIH₄) occurs at the less substituted carbon atom.

Conclusion

Reduction of the given transformation is carried out by using the LiALH₄+H₂O reagent.