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From the starting reactants given as the sole carbon source:

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We need to synthesis the following compound (we can use any inorganic reagents).

4-(1-bromo-2-methylpropyl)-2,3-dihydro-1H-indene

Here is what I tried so far, but I don't think it looks "realistic"

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    $\begingroup$ This is yet another exmple of a poorly thought out question that bears no resemblence to real world chemistry. I presume the question setter wants to see F-C alkylation with the di-bromopropane to set up the indane ring. The reality is that this will mostly give the products of rearrangement. $\endgroup$
    – Waylander
    Commented Dec 27, 2022 at 12:22
  • $\begingroup$ see chemistry.stackexchange.com/questions/91606/… $\endgroup$
    – Waylander
    Commented Dec 27, 2022 at 17:10
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    $\begingroup$ There is a difficulty with your last step. There are 3 possible benzylic sites for bromination and I think you will get a mixture. I would reduce the ketone to the benzylic alcohol and treat with PBr3 $\endgroup$
    – Waylander
    Commented Dec 27, 2022 at 20:16
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    $\begingroup$ @uhoh my rant is directed at the setter of the question the OP is attempting to answer $\endgroup$
    – Waylander
    Commented Dec 30, 2022 at 8:14
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    $\begingroup$ @uhoh as that comment is quoted in the answer I'm leaving it up $\endgroup$
    – Waylander
    Commented Dec 30, 2022 at 8:17

1 Answer 1

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I'll be frank about it....you can't get there from here! In @Waylander's words " This is ...a poorly thought out question...". Allow me to pose the question as it should have been asked. How does one synthesize 5-(1-bromo-2-methylpropyl)-2,3-dihydro-1H-indene 1 from benzene, propionic acid, and isobutyric acid?



Inspection of ketone 2 shows that a Friedel-Crafts acylation of indane 3 does not occur at $\ce{C4}$ but rather at $\ce{C5}$. The synthesis of bromide 1 from ketone 2 requires reduction to a benzylic alcohol (e. g.; $\ce{NaBH4/C2H5OH}$) followed by treatment with $\ce{HBr}$. Isobutyric acid and propionic acid are readily converted to their respective acyl chlorides with $\ce{SOCl2}$. As to the preparation of indane from benzene, this issue has been addressed previously on ChemSE.

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