Complete the following reaction using `G.R` and any other compound.
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Explanation

Direct reaction between a ketone and `G.R` gives `3^@` alcohol. Inspection of the product shows that the ketone has been converted to `2^@ RBr`, which is obtained from `2^@` alcohol be reaction with `HBr`. The product can be broken down into two fragments as shown :

Convert `(A)` into `2^@` alcohol by reduction with `NaBH_4` or `LAH`, then into `2^@ RX` with `HBr`, and then into `G.R` by reaction with `Mg`, which would give compound `(I)`
Reaction of compound `(I) (G.R)` with `(II)` would give `2^@` alcohol which on reaction with `HBr` would give the desired compound `(B)`.
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