Chapter 23, Problem 50PP

(a)

Interpretation Introduction

Interpretation:

With one given reagent and using any other reagents the preparation for given compound should be identified.

Concept Introduction:

Preparation of organolithium: They are prepared by reaction of organohalide in presence of two equivalents of $Li$.

    $\text{R-X}\stackrel{\text{Li}\left(\text{2eq}\right)}{\to }\text{R-Li + LiX}$

Preparation of Grignard reagents: They are prepared by reaction of organohalide in presence $Mg$ in ether solvent.

    $\text{R-X}\underset{E{t}_{2}O}{\overset{Mg}{\to }}\text{R-Mg-X}$

Reaction between Grignard reagent and water: Grignard reagents are strong bases which in presence of water forms hydrocarbon easily.

Gillman reagent: The lithium copper reagent compound $(R_{2}CuLi)$ is very useful because unlike Grignard reagent and organolithium reagents, they react with organic halides to replace the halide group with an alkyl (R) group.

• Organocuprate $(R_{2}CuLi)$ are also known as Gilman Reagent.
• It is prepared from an organolithium compound by reaction with cuprous iodide in diethyl ether or THF as follows.

  

Retro synthesis: It is a technique of planning an organic synthesis by the reverse approach.  In this technique, the starting materials are obtained by cleaving the target molecule into logical synthons.  Synthons are precursor fragments of the target compound when it is cleaved.  Depending on the stability, the synthons are classified as logical and illogical synthons.  Logical synthons are highly stable precursor fragments, and illogical synthons are less stable precursor fragments of the target compound.

(b)

Interpretation Introduction

Interpretation:

With one given reagent and using any other reagents the preparation for given compound should be identified.

Concept Introduction:

Heck reaction: It describes the coupling reaction between aryl, vinyl or benzyl halide and alkene in presence of $Pd$ catalyst.

    

Simmons–Smith reaction: It involves reaction of alkenes with organozinc reagent that is ${\text{ICH}}_{\text{2}}\text{ZnI}$ which results in formation of three–membered ring. This is a concerted reaction in which the configuration of starting alkene is preserved.

Retro synthesis: It is a technique of planning an organic synthesis by the reverse approach.  In this technique, the starting materials are obtained by cleaving the target molecule into logical synthons.  Synthons are precursor fragments of the target compound when it is cleaved.  Depending on the stability, the synthons are classified as logical and illogical synthons.  Logical synthons are highly stable precursor fragments, and illogical synthons are less stable precursor fragments of the target compound.

(c)

Interpretation Introduction

Interpretation:

With one given reagent and using any other reagents the preparation for given compound should be identified.

Concept Introduction:

Grubbs catalyst: This catalyst is used to achieve alkene metathesis.  It contain transition metal namely $\text{Ru}$ which is doubly bonded with carbon atom.

  

Dienes in presence of dilute solution, alkene metathesis serve as method of ring formation.

Retro synthesis: It is a technique of planning an organic synthesis by the reverse approach.  In this technique, the starting materials are obtained by cleaving the target molecule into logical synthons.  Synthons are precursor fragments of the target compound when it is cleaved.  Depending on the stability, the synthons are classified as logical and illogical synthons.  Logical synthons are highly stable precursor fragments, and illogical synthons are less stable precursor fragments of the target compound.