[Penguinone]

Question: identify the products in the following reaction, providing mechanisms for their formation. See picture below for compound, reagents and attempt.

Attempt:see picture below.

Any help will be greatly appreciated.

[discodermolide]

I can see where you are going, unfortunately I think in the wrong direction.
How does ethylene diol react with ketones under acidic conditions it give what product?

[Dan]

As an aside, the pinacol rearrangement is only likely if it can proceed via a stabilised carbocation. The carbocation in your suggestion is primary, so extremely energetically demanding. It will not compete with the reaction Discodermolide alluded to.

[Benzene]

I think the ethylyene glycol is used as a protecting group

http://www.organic-chemistry.org/protectivegroups/carbonyl/dioxanes-dioxolanes.htm

[discodermolide]

What does the OP think?

[Benzene]

I've noticed that these ethylene glycol based protecting groups are put on with catalytic acid, creating water, and that they are also removed with aqueous catalytic acid.

How do you manipulate the equilibrium to favor either the carbonyl or the dioxolane?

[discodermolide]

You usually use either a dehydrating acid of agent or better use toluene and Dean-Stark the water off at reflux.

[Benzene]

You usually use either a dehydrating acid of agent or better use toluene and Dean-Stark the water off at reflux.

a dehydrating acid reacts with water? or complexes with water?
Using a heat sensitive molecule would require the use of dehydrating acid, right? are there any other methods besides these two?

[discodermolide]

It can react or complex. Sometimes anhydrous copper sulphate is used to remove the water.

[Benzene]

It can react or complex. Sometimes anhydrous copper sulphate is used to remove the water.

So you would have to include the anhydrous copper sulfate in the reaction mixture with sulfuric acid, the compound, and the solvent?

is this protecting group formation pH dependent? or does it just have to be acidic?

I know deprotection is pH dependent.

[discodermolide]

If you use con sulphuric you don't need copper sulphate.
Usually you use p-TSA then you can add copper sulphate.
The reaction must be fairly acidic, the exact pH at which it does not work I don't know, but certainly pH 2 or less.

[Benzene]

So the copper sulfate added during the reaction complexes with the water as its formed preventing reverse reaction

Thank you! I appreciate your help.

[Penguinone]

Thank you for your replies.
Attempt 2 see picture below.

[kriggy]

Why it doesnt atack the carbonyl instead of ester? And I think you drew blue part wrong, there should be no double bond to oxygen and no positive charge. The hydroxy group atacks the  carbonyl carbon.

[Penguinone]

Thank you for your reply.

Attempt 3 see below.