[blondie915]

Hey guys! Stuck on another one. See the image below. This one can also occur in only five steps.
 
My thoughts:
I turned the aldehyde into a secondary alcohol by adding a grignard reagent (I'm not quite sure which grignard I should be adding here), then I oxidize turning the secondary alcohol into a ketone. This is where I get stuck because I want the double bonded oxygen to move over a carbon, how do I do that? And how can I add the alkyne again in regards to this problem?
 
Any help or input would be appreciated! Thank you so much!!

[critzz]

hint: epoxide

[Babcock_Hall]

What do you know about alkyne chemistry?  There is an important kind of reaction that is worth knowing.

[OCSaviour]

Step 1: Turn Aldehyde into an alcohol.
Step 2: Using E₂ mechanism, form an alkene.
Step 3: Add a hypohalous acid to the alkene
Step 4: Use CH₃C≡CMgBr
Step 5: Convert the alcohol group into a keto group.

[kriggy]

1) I dont think that mixing just grignard with the hydroxy-halide will work as you describe. 1st of all, you would probably need some kind of (paladium) catalyst for that and second of all,the halide might get converted into grignard itself and methylacetylene would just disapear as a gas  and 3rd: the grignard would decompouse because you have acidic proton in the molecule
2) It is preffered around here to give OP hints so he could figure the answer by himself instead of giving the answer right away