Compound A is an optically active alcohol. Treatment with chromic acid converts A into a ketone, B. In a separate reaction, A is treated with PBr₃, converting A into compound C. Compound C is purified, and then it is allowed to react with magnesium in ether to give a Grignard reagent, D. Compound B is added to the resulting solution of the Grignard reagent. After hydrolysis of the initial product (E), this solution is found to contain 3,4-dimethylhexan-3-ol. Propose structures for compounds A, B, C, D, and E.

Predict the products of the following reactions.

(a) sec-butylmagnesium iodide + D₂O

(b) n-butyllithium + CH₃CH₂OH

(c) isobutylmagnesium bromide + but-1-yne

Point out the flaws in the following incorrect Grignard syntheses.

(a)

Show how you would accomplish the following synthetic conversions.

(c)

Show how you would accomplish the following synthetic conversions.

(d)

Give the structures of the intermediates and products V through Z.

To practice working through the early parts of a multistep synthesis, devise syntheses of

(a) pentan-3-one from alcohols containing no more than three carbon atoms.

To practice working through the early parts of a multistep synthesis, devise syntheses of

(b) 3-ethylpentan-2-one from compounds containing no more than three carbon atoms.

Develop syntheses for the following compounds. As starting materials, you may use cyclopentanol, alcohols containing no more than four carbon atoms, and any common reagents and solvents.

(b) 1-chloro-1-ethylcyclopentane