Ok for G I tried first moving that double bond up, then the double bonded oxygen to an O- to form an enolate. Then I followed the hints and did a Michael reaction and an aldol reaction. This ended up forming the compound with the aldehyde group added to the same carbon the methyl is on with a double bond on the 1st and 2nd carbons on that chain. This answer proved to be wrong.
Next i tried forming an enolate by taking the hydrogen to the right of the top ketone. Then I did the same reaction adding the aldehyde compound to the carbon to the right of the original ketone. This answer was also wrong.
I can't see the formation of an enolate on the bottom chain ketone. I guess I just dont know which enolate is the most stable.
For K I don't exactly understand Mannich reactions at all. I have never done one in which the aldehyde isn't just a single carbon, so the reaction confused me. I added the Nitrogen group to the end of one end of the aldehyde and basically did one Mannich reaction but I don't see how another can occur.
For I, J and H I am thoroughly confused haha...
I guess for H the concentrated Sulfuric acid donates a proton to the OH and it leaves, the heat then allows the formation of a double bond, possibly in the middle of the compound. O3 then divides the molecule making 2 ketones possibly? NaoH/heat then removes one of them? No idea to be honest...
For I it looks like we have a Grignard Reagent with a protecting group on it... I'm not exactly sure where this is attatching. I guess the MgBr leaves and u have a negative on the end of it and the rest of the molecule attacks a + carbon, or maybe the double bond attacks it.
Overall your right, I find these very difficult. Textbook hasnt helped much either as the examples are very simple.