Quick o-chem question!

Factual Questions
1

Ok, so I have to make a presentation tomorrow for Chem Lit, and rather than doing the homework that I needed to in order to prepare it, I’m totally ripping off the powerpoint that I used in my Advanced Organic class. Problem is, I know that there was a mistake on a slide, and now I found it, but I can’t figure out for the life of me how to fix it! I know that CrO[sub]2[/sub] is an oxidizing agent, and will oxidize an alcohol into a ketone. If you look at the two structures in the top right, you see that they’re the same, even after the addition of the CrO[sub]2[/sub]. This is obviously wrong. I think that I just forgot to do something in the second structure, and I think that the one labeled 5 is correct, but I can’t tell.

Anyway, the slide that I’m referring to can be found here (go down to the first picture, the one that’s obviously of organic stuff… sorry about the lame host, but my photo class upload site is the easiest and fastest for me to upload to.)

Thanks, guys!

2

The structure in the top right is missing a carbonyl group in the five-membered ring - the same carbonyl that can be seen in the final product. The reagents CrO3 (not CrO2, hard to tell what is written on the scheme) and dimethylpyrazole will affect allylic oxidation on certain systems, such as this one. You should also indicate stereochemistry on each structure in the sequence.

If you want to impress your class - beyond the point of actually presenting the correct structures - check out the Goldfinger mechanism for that allylic bromination in the last set of transformations :wink:

3

Damn! The first real O-chem question in a while and I missed it. The Cocky Watchman’s got it right.

The stereochemistry is pretty easy and if indicated it may crowd the drawing, so I’m not certain that I would indicate it until the last structure. It took me a while to figure out why that bromination went stereospecifically, but I see that the Boc group probably blocks the other side.

4

Thanks!