[Serenagreene]

Does anyone have an example of the Stille couplng reaction mechansim?  Not the generic one, but one that actually uses real molecules and shows where the electrons are moving from and to where. 

Thanks!

-Serena

[Serenagreene]

Well I haven't found a good example yet, but can someone see if I'm pushing the electrons correctly?

Thanks,

-Serena

[agrobert]

In general, yes, your electron pushing conveys what products will be formed.  But conventionally organometallic reactions are drawn in a cycle that begins with Pd activation (Pd⁰) followed by oxidative-addition, insertion and reductive elimination and regenerates the catalyst.  It is good to see that you understand what bonds are broken and formed with the aide of Pd but with your arrow pushing it is difficult to predict side products.  Do you know about hapticity?

http://en.wikipedia.org/wiki/Hapticity

Some understand Pd catalyzed reactions as being coordinated side on as opposed to end on.  In more complicated mechanisms (alkynyl, cascades) it may be helpful to understand other types of transition metal coordination.  What do you know about Baldwin Rules for ring closure?

http://en.wikipedia.org/wiki/Baldwin's_rules

Attached are some more practice problems.  Generally the other reagents (bases, amines) are for Pd activation.

[Serenagreene]

Hapticity and Baldwin's rules are new to me.  So I'll have to review them some more.

When it says to propose a reasonable mechanism does that mean to show the arrows, or something like the attached (I tried to do problem a on the sheet - but I think I messed up the product before the final product).

Got to go to bed big calc test tomorrow night... 

-Serena

[agrobert]

This is a better reaction scheme for visual purposes.  It is common to write the name of the step next to the arrow where it is occurring.  For example, the first step is oxidative-addition.  Also this diagram lacks hydrogenation observed in the product.  Please try to post your own work or refer others only if necessary.  When you draw it out yourself it is easier for us to see your thought process and understanding.  There are several things wrong (mechanistic-shortcuts w/o explanation) in this scheme.