[OrganicH2O]

To Xshadow: The IBX should be making an aldehyde, not a carboxylic acid probably. Then, knoevenagle condensation followed by hydrolysis of both esters followed by decarboxylation of the beta-acid group. Edit: Also, you lost a carbon following the Sn2 adding the allyl group.

To Rolnor: in Clayden, et al (an awesome intermediate organic chem textbook, pages 617-618), a delta-lactone with two alpha hydrogens in shown doing a self-aldol process with a generic base.  Not claisen, but aldol! If there is one alpha hydrogen, like in this example, I would imagine opening the lactone via transesterification should be fine because aldol condensation is not possible. But anybody in a basic introductory organic class should NEVER propose something like this with a lactone. There is a chance it will confuse and anger the professor. The proposal of ring opening via transesterification seems very common.

[xshadow]

A bit tricky!!
Thanks guys!!

-So IBX oxidize the alcohol to an aldehyde.

-In the second last step the base deprotonates the 1,3 dicarboxylic compound and I have an aldolic condensation on the aldehydic group of my substrate (much more reactive than the esteric group).

But in the final step what happens?
I have HCl + heating

I suppose two things can happen!!!

1) HCl + H2O: acid  hydrolysis of the  esteric group to give a carboxylic acid

2) Cl-   1,4 nucleophile addition  to the michael acceptor generated  before with the aldolic condensation


Can 1) and 2) both happen?

Thanks ))

[OrganicH2O]

Definitely don't be adding Cl- via conjugate addition. This type of product is very unstable and would only form with a full equivalent of HCl or more, and when there is no other reasonable thing that could be happening. If it does happen, the heat will cause the HCl to fall back off.  HCl is very common as an acid catalyst. The chloride shouldn't be adding to anything.

H3O+ and heat will hydrolyze all esters to carboxylic acids, and then I think heat will cause one of the carboxylic acids to decarboxylate. If you are unfamiliar with decarboxylation, read about acetoacetic ester synthesis, or decarboxylation of carboxylic acids in general.

[xshadow]

Definitely don't be adding Cl- via conjugate addition. This type of product is very unstable and would only form with a full equivalent of HCl or more, and when there is no other reasonable thing that could be happening. If it does happen, the heat will cause the HCl to fall back off.  HCl is very common as an acid catalyst. The chloride shouldn't be adding to anything.

H3O+ and heat will hydrolyze all esters to carboxylic acids, and then I think heat will cause one of the carboxylic acids to decarboxylate. If you are unfamiliar with decarboxylation, read about acetoacetic ester synthesis, or decarboxylation of carboxylic acids in general.

Oh yes!!
There  is also decarboxylation

But after decarboxylation and ester hydrolysis I get an alpha-beta unsaturated aldehyde.

Can't (after those reactuonsl   Cl- react with the C=C-CHO giving 1,4 product?


Because in my textbook I have an example of HCl (Cl-) that gives a 1,4 product (Cl- attacks the C=C double bond)with a α-β unsaturated ketone.

Can't have also that reaction , after all the other one?

[OrganicH2O]

It's a ketone, not an aldehyde. But either way, a very good leaving group like a halogen at the beta position is very unstable. In heat, it should easily just do E1CB to eliminate HCl. Textbooks sometimes show examples of reactions that give fairly unstable products that will only work in a limited number of simple cases. I think addition of H-X to a conjugated enone falls into this category. In this example it is especially unreasonable because it is hydrolysis conditions, where there is a lot of water. Why not make a beta hydroxy? Beta hydroxy is also wrong though. With heat especially, the enone is favored.

I suppose if you suggest this answer your professor might accept it, based on your argument, but I don't think it's correct. Even more so because the decarboxylation requires heat.