Question

The major products X and Y formed in the following reaction sequences are:

• A.
• B.
• C.
• D.

Hint:

Reactions involving hydroboration followed by CO insertion typically yield aldehydes or ketones. When enolate chemistry is involved with sulfenylation and m-CPBA, anticipate oxidation and rearrangement. Watch for stereoelectronic control in the Alpha-functionalization.

Answer 1

The Correct Option is D

Step 1: Hydroboration–Carbonylation Reaction

• Thexyborane adds to the alkene via hydroboration.
• Then CO and H₂O are used under palladium catalysis for carbonylation (oxo process), giving an aldehyde intermediate.
• Final oxidation step (NaOAc, H₂O₂) leads to formation of a ketone.

This forms the X product shown in option (D): a cyclooctanone derivative with correct regioselectivity.

Step 2: Alpha-Functionalization via Enolate Chemistry

• LDA (base) forms the enolate.
• TMSCl traps the enolate as a silyl enol ether.
• PhSCl introduces a phenylsulfenyl group alpha to the carbonyl.
• m-CPBA oxidizes the PhS group to PhSO.
• Thermolysis results in a [2,3]-sigmatropic rearrangement and elimination to regenerate the carbonyl.

This process leads to a rearranged product Y consistent with option (D).

\[ \boxed{\text{Correct structures: X and Y are as shown in option (D)}} \]