Question

You are working in a laboratory, and you are given the task of converting cyclopentene into 1, 5-pentanediol. Your first thought is simply to perform an ozonolysis followed by reduction with LAH, but your lab is not equipped for an ozonolysis reaction. Complete the following alternative method for converting cyclopentene Into 1, 5-pentanediol. For help, see the section provided In a previous chapter on the reduction of esters to give alcohols. Using reagents (A H) from the table below, identify Reagent A and Reagent B. If more than one reagent is necessary, enter the reagents separated by a comma in the order they should be introduced (e.g. "C, A"). A: Na_2Cr_2O_7, H_2SO_4, H_2O B: PhaP = CH_2 C: KCN, HCN D: MeMgBr followed by H_2O E: LAH followed by H_2O F: O_3 followed by DMS G: H O H: OH Reagent A: ___________ Reagent B: ____________ Draw the structure of Intermediate C:

Answer 1

Answer:

Reagent A = $H_3O^+$

Reagent B=  $Na_2Cr_2O_7~H_2SO_4~H_2O$

Intermediate C= δ-Valerolactone

Explanation:

In the reaction from the alkene to the alcohol, we can use the alkene hydration in which the hydronium ion is added to the double bond followed by the attack of water to produce the alcohol.

Then in the conversion from alcohol to ketone can be produced if an oxidant reactive is used. In this case the Jones reagent ( $Na_2Cr_2O_7~H_2SO_4~H_2O$).

The intermediate is a structure produced by a peroxyacid. This reaction would introduce an ester group in the cycle generating the δ-Valerolactone (Figure 1).