[Snake]

Hey guys, in Hayashi's paper (Angew. Chem. Int. Ed. 2009, 48, 1304-1307), he made tamiflu with 3 one-pot reaction.

my question is,

1) Why did he add NH3 in his last step to form Zn(II)-NH3 complex? whats the purpose of Zn(II)-NH3 complex?

2) in his 2nd last step he added Zn/HCl to reduce NO2 to NH2, won't the Zn form ZnCl2?

Thank you.

[Fleaker]

Unfortunately, not everyone has access to the literature, nor is willing to go to the library to research the answer for your questions.


Please post up more details, not everyone is familiar with the substrate and reagents posted.


Thanks!

[Arkcon]

I can't help but wonder if it's not just a put-on, just random text put into an anonymous posting program.  A few days ago, someone responded to a 3-year old Tamiflu post with an advert.  Seems like Tamiflu is the new viagra.

[macman104]

I can't help but wonder if it's not just a put-on, just random text put into an anonymous posting program.  A few days ago, someone responded to a 3-year old Tamiflu post with an advert.  Seems like Tamiflu is the new viagra.

Sorry, incorrect on this one.

[AWK]

see:
http://totallysynthetic.com/blog/?p=1347
The previous step (before gaseous ammonia addition) use HCl  , the next K₂CO₃. The final isolation is through extraction which prefer homogenous solution.
There is an error on the scheme in the blog as well as in the original paper comcerning reduction of nitro group. It should be Zn, HCl/EtOH instead of Zn, TMSCl EtOH

[Snake]

Thank you AWK! =)

But i still got a doubt... when the nitro group is being reduced to the amine, Zn is being converted to Zn2+, and with the chloride ions present, it should form ZnCl2 right?

If so, by introducing NH3, does it displace the Chloride ions to form Zn(II)-NH3 complex?

or am i wrong, as in the Zn+2 ion does not form ZnCl2?

[AWK]

Zn + 2HCl = ZnCl₂ + H₂
ZnCl₂ + 4NH₃ = [Zn(NH₃)₃]Cl₂
Moreover, NH₃ neutralizes an excess of HCl

[Snake]

Thank you awk =)