[nachowithcheese]

Hi everyone, I'm trying to synthesize a molecule and would like to see if I have it right. My main issue was with the epoxide. I think with what I've done I'll end up racemic on that part. I'd like to type everything out, but I think this way might be easier. My apologies for my horrible handwriting and lack of being an awesome chemistry guy. Here's what I have so far...

Also forgot to mention, I wanted to reduce the ketone to an alkene and hit it with mCPBA, but I couldn't figure out how to accomplish that. That would eliminate my stereochemistry issue if I could get that done. Any suggestions?

[nachowithcheese]

Edit: sorry, had a idea failure

[discodermolide]

Edit: sorry, had a idea failure

What is the reagent you use for the transformation from the first ketone to the ester? (4th arrow) Is it trifluoroperacetic acid?

[nachowithcheese]

Yes. I thought the Baeyer-Villager would do that. For the epoxide I thought about hitting the final ketone with Br2 and H30+ to brominate the alpha carbon. Then, I was told that H2 Pd/C will completely reduce a ketone or aldehyde attached to a benzene so maybe that. Finally, take off the Br with t-BuO-/t-BuOH to make the alkene and then do mCPBA...yeah???

[discodermolide]

Yes. I thought the Baeyer-Villager would do that. For the epoxide I thought about hitting the final ketone with Br2 and H30+ to brominate the alpha carbon. Then, I was told that H2 Pd/C will completely reduce a ketone or aldehyde attached to a benzene so maybe that. Finally, take off the Br with t-BuO-/t-BuOH to make the alkene and then do mCPBA...yeah???

Seems ok!

[camptzak]

im confused a little at your sulfonation of the benzene ring. After the sulfonation would sodium hydroxide really remove the SO₃H by nucleophilic substitution?  
There is no Oxygen directly attached to the ring, the Sulfur atom is directly attached to the ring.

[nachowithcheese]

Should I have done SOCl3 instead of H2SO4?

[discodermolide]

Should I have done SOCl3 instead of H2SO4?

No that's fine.

[nachowithcheese]

I have another synthesis I'm pretty lost on. Anyone up for one more?

[camptzak]

Should I have done SOCl3 instead of H2SO4?

No that's fine.

would sodium hydroxide remove the SO₃H? The lone pair would end up on the Sulfur giving it a negative charge instead of oxygen. This does not make sense to me. can you explain further?

[camptzak]

I have another synthesis I'm pretty lost on. Anyone up for one more?

sure man, ill hammer synth problems all day. theyre fun. but im a rookie too, so im probably going to be incorrect in my predictions more than you are haha

[nachowithcheese]

You guys rock. Here she is. I see a claisen condensation that should probably happen with the first ester. I also see a michael reaction with 2nd ester that would add to the highly acidic alpha carbon between the product of the condensation, but I'm not sure how to get everything else on there and in the proper order.

[camptzak]

Ok i would like to see you do most of the heavy lifting on this one.

 If you try to hammer out the synth Ill think with you as you go. The claisen condensation is the starting block like you said.

one thing that immeadiatley jumps to mind is now your dealing with a β-carbonyl ester and you have to be careful to avoid decarboxylation. just something to think about as you plan the next step

its 2:26am here so ill probably check back tommorow.

[nachowithcheese]

Yes I'm working on it now. I'll write up the steps that I think might work in a few hours. It's late here too...awful...need bed...

[nachowithcheese]

Got it...I think. I did a Claisen with the top left ester, then added a bromine to the alpha carbon between the carbonyls. Then hit it with base to remove the bromine and make a double bond on the methyl group that was sticking out. Busted out a Stork to add the methyl to the alpha on the ketone. Took my thiophene, added a bromine, and added that to the alkene that I made. Took the pyridine and did NH3, OH-, and heat to swap the Cl for an NH2. Took that product with heat and switched out the ester that remained. Did a Michael rxn using the other starting material ester (the one with the alkene) that added onto the alpha C between the carbonyls and I got my final product. Hopefully thats right.