Question

Enediynes are a class of compounds that include some antibiotic drugs. Draw the structure of an "enediyne" fragment that contains six carbons in a row. (Hint: "di" means "two".)

Short answer

The enediyne fragment containing six carbons in a row can be represented by the structure: ``` C-C=C-C≡C≡C ``` This structure contains an alkene (ene) between the second and third carbons and two alkynes (diyne) between the fourth and fifth and fifth and sixth carbons.

Step-by-step solution

Start with six carbons in a row

First, draw a straight chain of six carbons, which will make up the backbone of our enediyne fragment. This will be the structure upon which we will add the alkene and diyne functional groups.

Add an alkene functional group

Considering that we have a total of six carbons, add a double bond between the second and third carbons to create the alkene (ene) portion of the enediyne fragment. The structure should now look like: ``` C-C=C-C-C-C ``` This double bond satisfies the "ene" part of the enediyne structure.

Add diynes

We need to add two triple bonds (diyne) to the structure while keeping the six carbons in a row. The best way to do this is to integrate two triple bonds into the remaining carbons. Place a triple bond between the fourth and fifth carbons, and another triple bond between the fifth and sixth carbons. The structure now becomes: ``` C-C=C-C≡C≡C ``` The final structure contains an alkene (ene) and two alkynes (diyne) with six carbons in a row. This compound has the desired enediyne fragment structure.