Chapter 8, Problem 50PP

(a)

Interpretation Introduction

Interpretation:

An effective synthesis for given transformation has to be suggested.

Concept Introduction:

• Hydroboration-oxidation reaction: Addition of $\text{–H and –OH}$ group across the double bond in presence of borane and hydrogen peroxide with base is known as hydroboration-oxidation reaction.  It follows Anti-Markovnikov addition.

• Anti-Markovnikov’s rule: An unsymmetrical alkene reacts with hydrogen halide in which halide ions goes to the less substitution position of carbon-carbon double bond which provides alkyl halides.

  

• Simple hydration in acidic media gives the addition product through carbocation intermediate and follows Markovnikov addition.
• An acid-catalysed hydration is shown below.

  

• Markovnikov’s rule: An unsymmetrical alkene reacts with hydrogen halide in which halide ions goes to the more substitution position of carbon-carbon double bond which provides alkyl halides.

  

(b)

Interpretation Introduction

Interpretation:

An effective synthesis for given transformation has to be suggested.

Concept Introduction:

Elimination reaction: In this reaction, two substituents are removed from the substrate to give the product in presence of base.  Elimination of compound in presence of bulky base leads to less substituted alkene, in presence of strong base (not bulky) leads to more substituted alkene.  A general elimination E2 mechanism is given as,

(c)

Interpretation Introduction

Interpretation:

An effective synthesis for given transformation has to be suggested.

Concept Introduction:

Catalytic hydrogenation:  It is the addition of molecular hydrogen in double bond in presence of metal catalyst.

Elimination reaction: In this reaction, two substituents are removed from the substrate to give the product in presence of base.  Elimination of compound in presence of bulky base leads to less substituted alkene, in presence of strong base (not bulky) leads to more substituted alkene.  A general elimination E2 mechanism is given as,

(d)

Interpretation Introduction

Interpretation:

An effective synthesis for given transformation has to be suggested.

Concept Introduction:

Syn-dihydroxylation: In this reaction alkene reacts with osmium tetroxide and gives an osmate ester.  Furthermore, the osmate ester treated with N-methylmorpholine N-oxide to form a cis-diol.