Question

Construct a multistep synthetic route from ethylbenzene to (2-bromoethyl)benzene by dragging the appropriate items into the bins. Note that each bin will hold only one item, and not all reagents and structures will be used.

Answer 1

To synthesize (2-bromoethyl)benzene from ethylbenzene, you can follow these steps: react ethylbenzene with EtMgBr in THF, treat the intermediate with 3-tributyltin-2-chloropyridine, reflux, and dioxane to obtain compound 9, react compound 9 with hydrazine and TiCl3, heat compound 10 with concentrated acetic acid, and treat compounds 9 and 10 with TFA/H₂O in THF.

Step-by-step explanation:

Synthetic Route from Ethylbenzene to (2-bromoethyl)benzene:

1. React ethylbenzene with EtMgBr in THF at 0 °C to form an ethylmagnesium bromide intermediate.
2. Treat the ethylmagnesium bromide intermediate with 3-tributyltin-2-chloropyridine, Pd(PPh3)4, Cu(I) Br, and 1,4-dioxane under reflux to obtain compound 9, which contains a bromoethyl substituent.
3. For compound 9, react with hydrazine at 80 °C, followed by treatment with TiCl3. For compound 10, heat with concentrated acetic acid at 110 °C.
4. Treat compounds 9 and 10 with TFA/H₂O (1/1) in THF to obtain (2-bromoethyl)benzene.

Answer 2

(1)NBS, ROOR (2)
`KOC(CH_(3))_(3)` and (3)HBr, ROOR

Step-by-step explanation:

Conversion of ethylbenzene to (2-bromoethyl)benzene involves three steps.

First step: allylic bromination of ethylbenzene in presence of NBS, ROOR. This step produces (1-bromoethyl)benzene.

Second step: E2 ellimination of HBr from (1-bromoethyl)benzene in presence of a strong base e.g. potassium t-butoxide [
`KOC(CH_(3))_(3)`]. This step produces styrene

Third step: HBr addition to double bond in presence of HBr, ROOR (antimarkonikov addition of HBr). Thus step produces (2-bromoethyl)benzene.

Full reaction scheme has been shown below.