[ruler9]

please help me with the mechanism of oxidation with cro3

Thanks in advance

[MissPhosgene]

Cr(IV not VI) abstracts a proton to make an allylic cation.

[orgopete]

Check the structure of the product, it doesn't look right. I am not saying it could not be the product, but it is unusual for a proton transfer to occur in the direction implied by the product. If oxidation at the allylic position to a carbonyl occurred that would make more sense.

[ruler9]

what if i use bromine in acetic acid as a second step
ref: j.chem.soc 1939, 1045

[MissPhosgene]

I think you can do it under the specified conditions. What sort of rearrangements can you think of?

[ruler9]

can you just explain me mechanism in detail, please can you draw it.. thanks for your reply.
i just saw the reference that they use bromine in acetic acid to make that double bond.

[MissPhosgene]

Unfortunately, I don't have drawing software available now.

Orgopete is right in that a 1,4-transposition is strange. If the drawing and reagents are correct, what you have to do is get the olefin in the right spot via cationic chemistry and then keep in mind that oxidation to the carbonyl takes place under these conditions to get to the enone.

 

[orgopete]

can you just explain me mechanism in detail, please can you draw it.. thanks for your reply.
i just saw the reference that they use bromine in acetic acid to make that double bond.

In that case, it sounds like:

1) BH3
2) H2O2/NaOH
3) CrO3, H2O, H2SO4
4) Br2, HOAc
5) DBU, heat

or something like that.

[MissPhosgene]

Ah, oKay. I didn't understand what you meant! So sorry!

can you just explain me mechanism in detail, please can you draw it.. thanks for your reply.
i just saw the reference that they use bromine in acetic acid to make that double bond.

[ruler9]

@MissPhosgene it's ok.
i would like to thankyou and Orgopete for helping me.

Ah, oKay. I didn't understand what you meant! So sorry!

can you just explain me mechanism in detail, please can you draw it.. thanks for your reply.
i just saw the reference that they use bromine in acetic acid to make that double bond.