[Rutherford]

What is the product of the attached reaction? I think that maybe the formyl group is introduced in one of the aromatic rings but I am not sure.

[discodermolide]

Chloroform plus conc. NaOH generates dichlorocarbene.
So look up the chemistry of carbenes. Also look up what you can do with the products. Start with simple examples such as addition to double bonds or insertion into C-H bonds or any other X-H bond. The product is effectively a "What" after hydrolysis?

[Rutherford]

Cyclopropanation would destroy the aromaticity, so I exclude it. The only reactions that wouldn't disturb the ring system would be insertion between N and Me or O and Me. As one product is obtained I would go with N-Me, but is it true?

[discodermolide]

Carbenes are electron deficient, Nitrogen has a ? pair.
sorry for the HUGE link
http://books.google.ch/books?id=XgICvI0-M0kC&pg=PA538&lpg=PA538&dq=nuciferine+and+dichlorocarbene&source=bl&ots=F3O2auGNoT&sig=XHBIhK8xOXODBnupMsCk6JG8Fpc&hl=en&sa=X&ei=1sUMU7qoBqTrywPayIHACw&ved=0CCwQ6AEwAg#v=onepage&q=nuciferine%20and%20dichlorocarbene&f=false

[Rutherford]

Okay, would this be the mechanism?

[discodermolide]

That looks ok. Great

[Rutherford]

Good. Thank you again.

[CrimpJiggler]

Cyclopropanation would destroy the aromaticity, so I exclude it. The only reactions that wouldn't disturb the ring system would be insertion between N and Me or O and Me. As one product is obtained I would go with N-Me, but is it true?

Nuciferine isn't fully aromatic though, the aliphatic portion about the N atom would be susceptible to cyclopropanation. My memory of carbene reactions is hazy, but from what I remember its not just double bonds they can react with, they can also insert themselves between C-H bonds. I agree with you that the carbene won't touch the benzene rings (won't disrupt the pi stacking anyway). As I said my knowledge is a bit hazy, I can't remember what the regiochemistry from carbene insertions.

[opsomath]

I am pretty sure those are normal formylation conditions and that it'll react ortho to the top methoxy from your figure to make a CHCl2 group which hydrolyses to the formyl group.

[discodermolide]

The book chapter I provided the link to suggests that this is a carbene reacting with the N lone pair.
50% NaOH and chloroform are conditions used for generating dichlorocarbene.
Now if the carbene does anything else, well it would not surprise me. But no yields are provided so it is difficult to say what else may be going on here.
Certain is that the CHCl₂ will give a formyl on hydrolysis.