Question

Draw the products formed when cholesterol is treated with each reagent. Indicate the stereochemistry around any stereogenic centers in the product.

1. ${\mathbf{CH}}_{\mathbf{3}}\mathbf{COCl}$
   
2. ${\mathbf{H}}_{\mathbf{2}}\mathbf{,}\mathbf{}\mathbf{Pd}\mathbf{-}\mathbf{C}$
3. PCC
4. $\mathbf{oleic}\mathbf{}\mathbf{acid}\mathbf{,}\mathbf{}{\mathbf{H}}^{\mathbf{+}}$
5. $\left[1\right]{\mathbf{BH}}_{\mathbf{3}}\mathbf{·}\mathbf{THF}\mathbf{;}\left[2\right]{\mathbf{H}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{2}}\mathbf{,}\mathbf{-}\mathbf{OH}$
   

Short answer

Answer

a.

The product formed when cholesterol treated with ${\mathrm{CH}}_3\mathrm{COCl}$

b.

The product formed when cholesterol treated with ${\text{H}}_2$, Pd-C

c.

The product formed when cholesterol treated with PCC

d.

The product formed when cholesterol treated with oleic acid, ${\text{H}}^{+}$

e.

The product formed when cholesterol treated with$\left[1\right]{\mathrm{BH}}_3·\mathrm{THF}{\mathrm{H}}^{+};\left[2\right]{\mathrm{H}}_2{\mathrm{O}}_2,{\mathrm{OH}}^{-}$

Step-by-step solution

About cholesterol

The yellowish crystalline-colored solid present in animal cell membranes is cholesterol. This is a class of lipid biosynthesized by animal cells. It is the principal sterol synthesized by almost all animals.

Reaction of cholesterol with acetyl chloride

When cholesterol reacts with acetyl chloride, the hydroxyl group of cholesterol gets replaced by the $C{H}_{3}COO$group. The reaction is shown below.

The reaction of cholesterol with ${\mathrm{CH}}_3\mathrm{COCl}$

Reaction of cholesterol with hydrogen and palladium

The reaction of cholesterol with ${\mathrm{H}}_2,\mathrm{Pd}-\mathrm{C}$will result in the formation of a product in which the double bond of the cyclohexane ring gets converted to a single bond. The reaction is shown below.

The reaction of cholesterol with${\mathrm{H}}_2,\mathrm{Pd}-\mathrm{C}$

Reaction of cholesterol with PCC

The reaction of cholesterol with PCC will give a ketone. The OH group of cholesterol becomes the ketonic group. The reaction is shown below.

The reaction of cholesterol with PCC

Reaction of cholesterol with oleic acid

The reaction of cholesterol with oleic acid will result in the formation of a product in which the OH group is replaced by the oleic acid group through an oxygen atom. The reaction is shown below.

The reaction of cholesterol with $\mathrm{oleic}\mathrm{acid},{\mathrm{H}}^{+}$

Reaction of cholesterol with borane and tetrahydrofuran

The reaction of cholesterol with borane and tetrahydrofuran will result in the formation of a product in which the double bond of a cyclohexane ring gets converted into a single bond, and the OH group will get attached.

The reaction is shown below.

The reaction of cholesterol with$\left[1\right]{\mathrm{BH}}_3·\mathrm{THF};\left[2\right]{\mathrm{H}}_2{\mathrm{O}}_2,-\mathrm{OH}$