• Blog Stats

    • 75,067 hits
  • Archives

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 156 other followers

  • Copyright notice

    This blog entry and all other text on this blog is copyrighted, you are free to read it, discuss it with friends, co-workers and anyone else who will pay attention.

    If you want to cite this blog article or quote from it in a not for profit website or blog then please feel free to do so as long as you provide a link back to this blog article.

    If as a school teacher or university teacher you wish to use content from my blog for the education of students then you may do so as long as the teaching materials produced from my blogged writings are not distributed for profit to others. Also at University level I ask that you provide a link to my blog to the students.

    If you want to quote from this blog in an academic paper published in an academic journal then please contact me before you submit your paper to enable us to discuss the matter.

    If you wish to reuse my text in a way where you will be making a profit (however small) please contact me before you do so, and we can discuss the licensing of the content.

    If you want to contact me then please do so by e-mailing me at Chalmers University of Technology, I am quite easy to find there as I am the only person with the surname “foreman” working at Chalmers. An alternative method of contacting me is to leave a comment on a blog article. If you do not know which one to comment on then just pick one at random, please include your email in the comment so I can contact you.

Taxifolin

Dear Reader,

As I wrote earlier today, I will address the question of how to make taxifolin which the paper Yang, et. al. in Journal of Medicinal Chemistry,  2009 ,  volume 52,  issue 23, pages 7732 to 7752 does address. Now before you ask taxifolin is needed for the production of a series of herbal drugs. While for small amounts it might be perfectly OK to collect drugs from some rare plants for the production of drugs for mass treatment of humans it is often a good idea to make the drug in a factory by means of organic synthesis. This will drive down the price (with some luck) and make the drug supply independent of the plant or tree.

Before we get any further here is our synthesis target.

Taxifolin

I would be a good idea before we go any further to ask ourselves why it is unlikely that the taxifolin will not rearrange via an enol form to give the following species.

Other isomer of taxifolin

I think that the reason why the molecule is found in the first form is that the ketone group is conjugated to benzene ring on the left, but if we move the ketone to the alternative location it is not conjugated any more. But back to the synthesis, now the best thing to do when planning a synthesis is to use the retrosynthetic method. This is to break the molecule up in your mind to work out a way to make the molecule.

Retrosynthesis

After we have chosen a good disconnection we now need to work out a reagent which will represent the odd looking thing with the negative and positive charge. Now the negative charge on the oxygen can be provided by the lone pair of a phenol oxygen, while the positive charge can be provided by an epoxide (three membered cyclic ether) if we protonate the epoxide. Now it is important to note that when an epoxide is opened under acidic conditions that the regioselectivity (which way around the epoxide reacts) is dictated by the stability of the hypothetical carbocations formed when the protonated epoxide ring opens. Below is a diagram which will make it more clear.

Ring opening of the epoxide

I will discuss the chemistry required to form the epoxide compound at a later date.

Advertisements

Go on, Have your say !

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: