Be sure to answer all parts. identify a, b, and c, intermediates in the synthesis of the five-membered ring called an α−methylen
e−γ−butyrolactone. this heterocyclic ring system is present in some antitumor agents. do not draw lone pairs in your answers. 23191 draw structure ... draw structure ... draw structure ... a b c
1 answer:
The complete reaction along with intermediates is given below, with each step highlighted in different color.
Step 1:
In this step an acidic proton at alpha position is abstracted from lactone moiety and corresponding enolate is formed, which is resonance stabilized. Both structures are shown. In this case LDA (<span>Lithium diisopropylamide) acts as a base.
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Step 2:
The enolate formed attacks on Methyl Iodide, as Iodide being greater in size is a good leaving group and alpha methyl moiety is generated.
Step 3:
This step is acid catalyzed Bromination. Bromine is added at alpha position.
Step 4:
This is elimination reaction and is according to <span>Hofmann's Rule. Here less substituted alkene is generated.</span>
Step 1:
In this step an acidic proton at alpha position is abstracted from lactone moiety and corresponding enolate is formed, which is resonance stabilized. Both structures are shown. In this case LDA (<span>Lithium diisopropylamide) acts as a base.
</span>
Step 2:
The enolate formed attacks on Methyl Iodide, as Iodide being greater in size is a good leaving group and alpha methyl moiety is generated.
Step 3:
This step is acid catalyzed Bromination. Bromine is added at alpha position.
Step 4:
This is elimination reaction and is according to <span>Hofmann's Rule. Here less substituted alkene is generated.</span>
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