Organic Synthesis of Molecules

[Aziz Sergeyevich]

Hi,

I need some help regarding my understanding of organic synthesis. I was reading over some class notes, and found a diagram which showed a molecule and stated that it could be used as a precursor for a synthesis reaction. It said, that the synthesis of it could lead to multiple products due to stereoisomersim, optical isomerism or multiple reactive sites giving unintended products. I have attached the image of the molecule below and would be very appreciative of any help with this!!

Cheers,

Az.

 

[Iota]

Hi,

I need some help regarding my understanding of organic synthesis. I was reading over some class notes, and found a diagram which showed a molecule and stated that it could be used as a precursor for a synthesis reaction. It said, that the synthesis of it could lead to multiple products due to stereoisomersim, optical isomerism or multiple reactive sites giving unintended products. I have attached the image of the molecule below and would be very appreciative of any help with this!!

Cheers,

Az.

 

 

 

So what do you understand stereoisomerism and optical isomerism to be?

 

Can you name the functional sites on the molecule you posted?

 

Lastly, was you given a final product that you were aiming to make? Otherwise we could do many things to the organic compound.

[Aziz Sergeyevich]

Stereoisomerism, is in my understanding, the ability of a molecule to allow different spatial arrangement. While, optical isomerism is a form of stereoisomerism in which molecules are non-superimposable. See, this is where my chemistry understanding lacks... I think the functional groups are the double carbon bonds in this reaction as they are electron dense thererfore susceptible to an electrophile, but i am not positive on that... Pretty sure there is also a chiral carbon in the molecule.. Nope, no final product. The idea of the task was to prove that by performing a reaction say Friedel Crafts Alkylation or Birch Reduction, one could attain more than one product.. or a product that can have stereoisomers...

[Fuzzwood]

It indeed has a chiral center. There are 2 forms of stereoisomerism: cis-trans isomerism, and optical isomerism. Only the latter can be applied here. There are 2 more functional groups in this molecule.

[Iota]

Remember, a functional group can be defined as: the part(s) of the organic molecule that takes part in chemical reactions. (You're correct about the C=C.)

 

Look into the chemical reagents used for Birch's Reduction and Friedel-Crafts Alkylation (both which are used to alter C=C bonds) and see if you think they will affect any other groups. That should answer the question.

 

Hope this helped!

[John Cuthber]

It indeed has a chiral center. There are 2 forms of stereoisomerism: cis-trans isomerism, and optical isomerism. Only the latter can be applied here. There are 2 more functional groups in this molecule.

Sure about that?

The C6 ring is roughly flat.

Th C1 addendum can be above or below the ring. So can the C3 bit at the other end. So they can be on the same side or different sides.

"same side" can't inter-convert to "different side" without breaking bonds.

[Fuzzwood]

Àh you are talking about axial-equatorial shifts? That can of course still happen. I was specifically talking about orientation around the double bonds.

[Aziz Sergeyevich]

Looking at Friedel-Crafts Alkylation it has become quite clear that there are multiple additions that occur. So, the dialkylated material is produced along with the desired monoalkylated product. So I am guessing this would mean multiple products could occur if a a Friedel Crafts Alyklation were to be performed on that molecule.. One question is Friedel-Crafts Alkylation also known as Electrophilic Aromatic Subsitution?

Also, would anyone be able to help me with which functional groups apart from the C=C it affects... Been researching for a while and cant find anything on it :S

[hypervalent_iodine]

1344970105[/url]' post='696914']

Àh you are talking about axial-equatorial shifts? That can of course still happen. I was specifically talking about orientation around the double bonds.

 

Substituents at axial and equatorial positions can also be described as being cis or trans relative to one another.

 

1344993672[/url]' post='697028']

Looking at Friedel-Crafts Alkylation it has become quite clear that there are multiple additions that occur. So, the dialkylated material is produced along with the desired monoalkylated product. So I am guessing this would mean multiple products could occur if a a Friedel Crafts Alyklation were to be performed on that molecule.. One question is Friedel-Crafts Alkylation also known as Electrophilic Aromatic Subsitution?

Also, would anyone be able to help me with which functional groups apart from the C=C it affects... Been researching for a while and cant find anything on it :S

 

FC alkylations and acylations are aromatic substitution reactions. Your compound is not aromatic.

Is this an actual question posed in the book? It seems too broad to have one clear answer.

[Aziz Sergeyevich]

Is this an actual question posed in the book? It seems too broad to have one clear answer.

It is an 'research and evaluation' question... It is meant to help broaden one's understanding of organic synthesis and the problems surrounding it - in this case, the problem of multiple products which give rise to difficulty in separation in particular in pharmaceuticals whereby isomers can be detrimental or beneficial to a human and it is of paramount importance not to mix isomers up....

[Aziz Sergeyevich]

hmm, looking back, neither reaction can really be utilised can they? because both FCA and Birch Reduction are designed for aromatic compounds...

 

what about grignard reaction? that would potentially affect the molecule to produce multiple products wouldnt it?

[hypervalent_iodine]

1345028424[/url]' post='697090']

hmm, looking back, neither reaction can really be utilised can they? because both FCA and Birch Reduction are designed for aromatic compounds...

 

what about grignard reaction? that would potentially affect the molecule to produce multiple products wouldnt it?

 

You need to think about this yourself instead of just randomly stating reactions. If you did a Grignard reaction on your compound, what do you think the product(s) would be?

 

A much easier way to approach this is to identify your functional groups and list the reactions you know you can perform on those groups and draw your predicted products. You would then be able to cross check to see if the reagents used in one reaction for one of the functional groups also has an affect on one of the others. Going about this in the reverse direction - I.e. by naming reactions and then seeing if they fit your compound - is going to quickly lead you astray.