[stockdt]

Im working on putting a reaction mechanism for a paulson khan reaction together cited in this paper : there is an image of the scheme from the paper below as well.


DOI: 10.1002/anie.201608206


instead of doing the reaction under a CO atmosphere they use triethyl amine N-oxide to oxidize the system which then creates the 5.6.6 ring system. However putting the mechanism together has me stuck. the way i have it drawn im going to form a 4.7.6 ring system. does this undergo rearragement? and how exactly does the Et3N N-oxide come into play? does it form a cobalt oxide, or does it bind straight to the alkene? if i use a molecule of CO to carbonylate my system i have 1 to many carbons present. any help is MUCH appreciated!
imgur link below shows what i have put together so far. imtermediate 3 and 4 are currently the same because i deleted some things.


my work: http://imgur.com/IUSIoui

from the paper: http://imgur.com/qi5X97E

[clarkstill]

In your step 2, try migrating one of the C-Co bonds at the benzylic position - this will give you the 6 membered ring you need, and the 6-exo-trig reaction should be faster than the 7-exo you have drawn.

Then you need to do a migratory insertion of one of the CO ligands from cobalt into the Co-C bond.

The role of the N-oxide is apparently to oxidize one of the CO ligands to generate a more reactive reagent, according to this:

https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-1995-5170